Evaluation of the safety and efficacy of using human menstrual blood-derived mesenchymal stromal cells in treating severe and critically ill COVID-19 patients: An exploratory clinical trial

评估使用间充质基质干细胞治疗重症和危重症新冠患者的安全性和有效性：一项探索性临床试验

Abstract

The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in December 2019 and has subsequently spread worldwide. Currently, there is no effective method to cure COVID-19.

Mesenchymal stromal cells (MSCs) may be able to effectively treat COVID-19, especially for severe and critical patients. Menstrual blood-derived MSCs have recently received much attention due to their superior proliferation ability and their lack of ethical problems. Forty-four patients were enrolled from January to April 2020 in a multicenter, open/label,nonrandomized,parallelcontrolled exploratory trial. Twenty-six patients received allogeneic, menstrual blood-derivedMSC therapy,and concomitant medications (experimental group),and 18 patients received only concomitant medications (control group). The experimental group was treated with three infusions totaling 9 × 107 MSCs,one infusion every other day. Primary and secondary endpoints related to safety and efficacy were assessed at various time points during the 1-month period following MSC infusion. Safety was measured using the frequency of treatmentrelated adverse events (AEs). Patients in the MSC group showed significantly lower mortality (7.69% died in the experimental group vs 33.33% in the control group; P = .048). There was a significant improvement in dyspnea while undergoing MSC infusion on days 1, 3, and 5. Additionally, SpO2 was significantly improved following MSC infusion, and chest imaging results were improved in the experimental group in the first month after MSC infusion. The incidence of most AEs did not differ between the groups. MSC-based therapy may serve as a promising alternative method for treating severe and critical COVID-19.

由严重急性呼吸综合症新冠2 (SARS-CoV-2)引起的，2019的新冠病毒，在2019年12月被确诊并且在世界各地广泛传播。近期，对于治疗COVID-19没有有效的方法。MSCs治疗COVID-19可能有效，特别是重症和危重症患者。MSCs由于超强繁殖能力和缺乏伦理问题近期受到大量关注。在一项多中心、开放、不随机、无平行对照的探索性试验中从2020年1月到4月入组44例患者。26例患者接受异体经血MCS治疗和伴随用药（试验组），18例患者只接受伴随用药（对照组）。试验组接受三次输液合计9 × 107 MSCs，每隔一天输一次。根据MSC注射后一个月内的重要时间节点评估与安全性和有效性有关的主要及次要指标。安全性评估使用与药物相关的不良事件。在MSC组患者显示显著的低死亡率(试验组7.69%。对照组33.33%，P=0.048)。在第1、3、5天接受MSC注射呼吸困难有显著改善。另外，SpO2在MSC注射后有显著改善，并且在试验组注射MSC后的第一个月胸部成像结果得到改善。大部分AEs发生率在组间没有差异，基于MSC疗法可能作为一项治疗重症和危重症新冠患者有前景的替代疗法。

Mortality=death rate

Incidence：

Therapy=treat

Serve as =considered

Promising=hopeful

Alternative=alter+native=改变+原来的，当地人=替代

翻译难点，

may serve as的翻译，直译为作为一项方法为患者服务，三个信息点，它是基于MSC的一项疗法，它可能作为一项最有前景的替代疗法，它是为重症和危重症新冠患者服务的。

（2）every other day，新知识，每隔一天。

2021年6月8日星期二（第1天翻译250个词）

1.introduction

The coronavirus disease 2019 (COVID-19), caused by severe~acute respiratory syndrome coronavirus 2 (SARSCoV2), was initially identified in December 2019 as causing a cluster of respiratory infections.1,2 COVID19 quickly attracted global concern and panic since it is highly contagious.3–5 Due to a lack of adequate awareness in the first few weeks of the outbreak, the number of infected patients increased swiftly, rapidly spreading to more and more countries.6,7 As of January 7, 2021, there have been over 85 929 000 confirmed cases of COVID-19 worldwide,leading to 1 876 100 deaths. Currently, the number of infected patients is still increasing worldwide.

这个新冠疾病2019（COVID-19），由严重急性呼吸综合冠状病毒2(SARS-CoV-2)引起的，在2019年12月被明确定义为引起一系列呼吸道感染。COVID-19由于高度传染性快速引起全球广泛关注和恐慌。由于在爆发开始的几周缺乏足够的意识。感染患者人数极速增加，传播到越来越多的国家。在2021年7月，在全球已经超过了85929000 COVID-19确诊病例，导致1876100人死亡。进来，感染患者的人数仍然在全球持续增加。

COVID19 has an incubation period which can range from 1 to 14 days but usually ranges from 3 to 7 days.8 The main symptoms are fever, headache, dry cough, and chest tightness.911 Many patients also experience a sore throat, diarrhea, nasal congestion, and rhinorrhea.12,13

Severe patients often develop expiratory hyperextension and dyspnea 1 week after the onset of the disease. In the most severe cases, patients can quickly develop acute respiratory distress syndrome (ARDS), severe acute lung injury, septic shock, metabolic acidosis, and coagulopathy,as reported in a biopsy and autopsy study.14 COVID-19 can easily cause expiratory dyspnea and ARDS. Of the COVID-19 patients, 13.8% of the cases were severe, 6.1% cases were critical, and about 2.3% cases had fatal outcomes.Since no effective or authorized vaccines are available for preventing COVID19 infections, a breakthrough in the therapeutic strategy is vital for the treatment of COVID19 and especially for severe or critically ill patients who may develop ARDS and/or expiratory dyspnea.17–21 Currently,a few drugs (such as remdesivir and dexamethasone)have shown positive preliminary results in randomized,controlled, open.label, clinical trials.22,23 Even more excitingly, COVID19 vaccines with acceptable safety, tolerability,and immunogenicity have been reported by Zhuet al and Folegatti et al as being effective in initial human clinical trials. Apart from these, many other groups are also developing available vaccines such as the BNT162mRNA vaccine26 sponsored by Pfizer Inc. and BioNTech SE; the chimpanzee adenovirus vectored vaccine ChAdOx1 nCoV-19 (AZD1222) sponsored by AstraZeneca;the mRNA-1273 vaccine29 codeveloped by the Cambridge,Massachusetts-based biotechnology company Moderna,

Inc., and the National Institute of Allergy and Infectious Diseases (NIAID); the adenovirus serotype 26 (Ad26) vaccine30 developed by Janssen Vaccines & Prevention B.V.; the BBIBP-CorV vaccine31 developed by the Beijing Institute of Biological Products; the CoronaVac vaccine developed by Sinovac Life Sciences; and the NVX-CoV2373

Vaccine sponsored by Novavax, Inc. However, no specific drugs have been reported to be absolutely effective in treating COVID-19. Moreover, SARS-CoV-2-induced secondary infections have been reported to induce multiple organ dysfunction syndrome in severe or critically ill patients, and this issue remains a serious problem worldwide.

COVID-19的孵化周期是1-14天，但一般范围是3-7天。最重要的症状是发烧、头痛、干咳、胸闷。一些患者也会经历咽喉疼痛、腹泻、鼻塞、流鼻涕。重症患者通常在发病一周后出现呼吸性伸展和呼吸困难（onset进攻）。根据活检和尸检研究报告，在最严重的情况下，患者很快发展成急性呼吸窘迫综合症（ARDS），急性重症肺部损伤，感染性休克、代谢酸中毒、凝血病。COVID-19很容易引起呼气型呼吸困难和ARDS。COVID-19患者中，13.8%病例是重症，6.1%病例是危重症，并且大约2.3%病例有致命结果。由于没有有效和权威的疫苗能够阻止COVID-19感染，COVID-19治疗尤其改善ARDS和呼气型呼吸困难的重症和危重症患者的治疗策略的突破十分关键。近期，在一项随机、对照、开发标签的临床试验一些药物显示了初步的阳性结果。甚至更加激动人心的是，具有可接受的安全性、耐受性和免疫原性的COVID-19疫苗被zhu等人和Folegatti等人报道了。除了这些，其他研究小组也发展了可接受疫苗，

例如：（1）Pfizer（辉瑞）和BioNTech SE赞助的BNT162 mRNA苗；

（2）AstraZeneca（阿斯利康）赞助的黑猩猩腺病毒载体疫苗ChAdOx1 nCoV-19 (AZD1222)；

（3）由位于马萨诸塞州剑桥市的生物技术公司 Moderna, Inc. 和美国国家过敏和传染病研究所 (NIAID) 共同开发的 mRNA-1273 疫苗；

（4）由Janssen Vaccines & Prevention B.V.研发的腺病毒血清型 26 (Ad26)疫苗

（5）北京生物制品研究所研制的BBIBP-CorV疫苗

（6）Sinovac生命科学研发的CoronaVac疫苗

（7）Novavax, Inc赞助NVX-CoV2373疫苗

然而没有特别的药物被报道对治疗COVID-19明显有效。而且， SARS-CoV-2 引起的继发感染被报道可促使重症和危重症患者多组织功能障碍综合症，这个问题仍然是全球范围内的一个严重问题（induce重点谓语翻译错误，诱导、促使；remain翻译错误，本意是仍然）。

Mesenchymal stem cells have been used for almost three decades, and have made great progress.34 According to the recommendations of the International Society for Cell & Gene Therapy (ISCT) in 2019, mesenchymal stem cells should be named mesenchymal stromal cells (MSCs).35 MSC-based cellular therapy has been the subject of an increasing number of studies due to the cells’ self-renewing capacity, multipotent potential, low immunogenicity, anti-inflammatory activity, and ability to home to damaged tissue.More importantly, MSCs have unique immunomodulatory functions of both innate and adaptive immune responses, making them an attractive cell therapy tool.38,39 MSCs regulate adaptive immune responsesmainly through targeting T lymphocytes, B lymphocytes,antigen-presenting cells (APCs), dendritic cells (DCs), natural killer (NK) cells, and regulatory T cells (Tregs).38 MSCs also regulate innate immune responses mainly through targeting DCs, NK cells, innate TH17 cells, neutrophils, monocytes, macrophages, and mast cells.39 Further,MSC-based therapies have shown promising

results in several clinical studies across a variety of diseases.40,41 With the development of stem cell research,researchers have found that after injecting MSCs, the human body activates the host’s innate immune cascade system, such as complement and blood coagulation,which is defined as the instant blood-mediated inflammatory esponse (IBMIR).42 IBMIR is of key importance onsidering the highly procoagulant state of many critically nd severely ill patients in need of MSC therapy.43 SCs can be obtained from various sources, including one marrow (BM), adipose (AD), umbilical cord (UC),placenta, menstrual blood, muscle, dental pulp, Wharton’s elly (WJ), fetal liver, amniotic membrane, amniotic luid, urine etc.44–48 Furthermore, MSC-based treatment has demonstrated promising results in studies on inflammatory lung disease, showing an ability to inhibit alveolar collapse, cell apoptosis, and collagen accumulation in lung tissues.49 The angiotensin-converting enzyme 2 (ACE2) is identified as a receptor of SARS-CoV-2 entering into target cells.50,51 In addition, researchers have demonstrated

thatMSCs do not express ACE2, andMSCs are resistant to SARS-CoV-2 infection as well as when exposed to SARSCoV-2-infected cells.52,53 Additionally, following infusion of allogeneic MSCs into nine patients with ARDS, Wilsonet al54 observed no prespecified side effects including cardiac arrhythmia, hypoxemia, and ventricular tachycardia.Further, our team reported that MSC transplantation significantly lowers the mortality of epidemic Influenza A (H7N9)-induced ARDS patients.55 BM-MSCs have been shown to improve repair after ventilator-induced lung injury, to facilitate the resolution of inflammation, and to restore lung function and structure in ARDS patients.56 With regard to the COVID-19 epidemic, MSCs from different sources (especially UC-MSCs) have been used in clinical trials.53,57 A good proliferation rate plays an important role in clinical application, because stem cell-based treatment is dose-dependent, and usually human clinical research requires millions of stem cells. The doubling time for menstrual blood-derived MSCs is about 20 h, and the doubling time for BM-MSCs is about 40-45 h. Thus, MSCs from menstrual blood can obtain a better yield within a shorter time at early passages.58,59 More importantly, menstrual blood-derived MSCs offer an alternative that is both painless and free of the ethical issues that may arise from BM-MSCs donations.60 Thus, menstrual bloodderivedMSC-

based therapy may be a promising treatment for COVID-19, particularly to combat the inflammatory cytokine storms observed in severe and critical patients.

间充质干细胞被使用已经有30年了，并且有很大的进步。在2019年根据科学家的解释推荐细胞联合基因治疗，间充质干细胞被命名为间充质基质细胞(MSCs)。基于MSC的细胞疗法，由于自我新生能力，多种潜在能力，低免疫原性，抗炎活性，修复受损组织能力等成为了研究数量逐增的课题。更重要的是，MSCs在先天性和适应性免疫反应，有独特的免疫调节，让他们成为有吸引力的细胞治疗工具。MSCs调节适应性免疫反应主要通过靶向T淋巴细胞、B淋巴细胞、抗原呈递细胞、树突状细胞、自然杀伤细胞和调节性T细胞。MSCs也可以调节先天性免疫反应主要通过靶向DCs、NK细胞、先天TH17细胞、中性粒细胞、单核细胞、巨噬细胞、肥大细胞。更进一步来说，基于MSC治疗显示良好的结果在通过各种疾病的多项临床研究中。随着干细胞的研究发展，研究者发现接种MSCs之后。人体激活宿主。IBMIR要至关重要的考虑到需要MSC治疗的许多重症和危重症患者的高度凝血状态。MSCs可以从不同的来源获取，包括包括骨髓（BM）、脂肪（AD）、脐带（UC）、胎盘、经血、肌肉、牙髓、沃顿氏胶（WJ）、胎肝、羊膜、羊水、尿液等。此外，基于MSC治疗在炎症性肺部疾病研究中表明有非常可观的结果，显示了抑制肺泡塌陷、细胞凋亡和肺组织中胶原蛋白积累的能力。ACE2被鉴定为SARS-CoV-2进入靶细胞的受体。另外，研究者表明MSCs没有表达ACE2，MSC 对 SARS-CoV-2 感染以及暴露于 SARS-CoV-2 感染的细胞具有抵抗力。

另外，同种异体MSCs注射进入9个ARDS患者, Wilson等人没有观察到提前制定的副作用，包括心律失常、低氧血症和室性心动过速。

另外，我们的团队报告MSCs细胞移植显著降低流行性甲型流感（H7N9）诱发的ARDS患者的死亡率。BM-MSCs也显示可以提高呼吸机所致肺损伤后修复，促进炎症的“再解决”消退，并恢复 ARDS 患者的肺功能和结构。随着COVID-19的流行，不同来源的MSCs已经使用在临床试验中。在临床试验中一个良好繁殖率起着非常重要的作用，因为基于干细胞治疗具有剂量依赖性，并且通常人类临床研究者要求数百万的干细胞。经血MSCs的倍增时间约是20h，BM-MSCs的倍增时间约是40-45h。因此，在早期的短时间内来自经血的MSCs可以获得更好的量。更重要的是，来自经血的MSCs提供一种可替代方案，既无痛和也没有来自BM-MSCs捐献者产生的伦理问题（alternative名词，替代方案）。因此，基于经血来源的MSCs可能是最有前景的治疗方法，对于COVID-19，特别是对抗在重症和危重症患者观察到的炎症细胞因子风暴。

This study is an exploratory trial to assess the ability of menstrual blood-derived MSCs to treat severe and critically ill COVID-19 patients. To this end, we assessed the safety, therapeutic efficacy, and tolerability of transplanted MSCs with a 1 month follow-up after SARS-CoV-2 infection. In particular, we assessed any improvements in pulmonary

function. Our results not only shed light on the ability ofMSCs to treat COVID-19 patients, but also suggest that MSCs are a promising tool to treat acute or chronic pneumonia in future clinical applications.

这个研究是评估经血MSCs治疗COVID-19重症和危重症患者能力的一项探索性是试验。在最后，我们评估了SARS-CoV-2感染后MSCs移植一个月随访的安全性，治疗有效性，以及耐受性。特别是我们评估了肺功能的一些改善。我们的结果不仅揭示患者MSCS治疗COVID-19患者的能力，也表明在未来临床应用中，MSCs对于治疗急性或慢性肺炎是非常有前景的工具。

(2021年7月6日星期二翻译完)

2 MATERIALS AND METHODS

2.1 Study design and participants

This was a multicenter, open-label, nonrandomized, and parallel controlled phase I clinical trial performed at two major academic centers in China: the Renmin Hospital of Wuhan University, Wuhan and the First Affiliated Hospital,College of Medicine Zhejiang University, Hangzhou.

The Shulan (Hangzhou) Hospital, affiliated to Zhejiang Shuren University, Shulan International Medical College,Hangzhou also participated in related studies. Eligible patients were 18-75 years old and confirmed to be positive for the SARS-CoV-2 RNA virus by polymerase chain reaction (PCR) analysis performed within biological safety protection level 3 laboratories at Wuhan University and Zhejiang University. Before the initiation of this study, the research protocol, case report form (eCRF), and informed consent form were each obtained and approved by the Ethics Committees of Renmin Hospital of Wuhan University (WDRY2020-K011) and the First Affiliated Hospital,College of Medicine, Zhejiang University in accordance with the Declaration of Helsinki and the criteria of Good Clinical Practice.61 This clinical trial was also registered in the Chinese Clinical Trial Registry (ChiCTR2000029606).

The investigators fully educated each patient’s legal representative

regarding the informed consent form, the detailed therapeutic procedure, aswell as the possible risks and benefits. The patients had the right to withdraw from this clinical study at any time during the clinical trial. Considering the urgency of the COVID-19 epidemic and the operability of the enrollment process, a randomized table was not used for randomization in the research process at Renmin Hospital of Wuhan University, and cases (including severe and critically ill patients) were matched based on similar severity levels and similar timing of enrollment/in the study. This clinical trial was an open study and did not involve blinding or emergency unblinding.

2 材料与方法

2.1 研究设计和参与者

这是一个在中国两个重要的学术中心开展的多中心、开放、不随机、平行对照一期临床试验。武汉大学人民医院和浙江大学医学院附属第一医院也参与了相关研究。符合资格的病人是18-75岁并且在武汉大学和浙江大学在3级生物安全性保护中被RCT分析确认SARS-CoV-2 RNA阳性的。研究开始之前，这研究的安慰剂、eCRF和标准文档格式被（武汉大学人民医院和浙江大学医学院附属第一医院的）伦理委员会按照赫尔辛基宣言和GCP标准获取和同意。该临床试验也在中国临床试验注册中心进行注册。研究者要充分通知每一个患者法律代表，包括标准文档格式、详细的治疗过程和可能的风险受益。在临床试验进行的任何时间患者都可以从临床研究中退出。考虑到COVID-19疫情的紧急性和入组过程的可操作性，随机表不适用在武汉大学人民医院的研究过程，案例匹配基于研究中相似的严重程度和相近的入组时间。这个临床试验是开放性研究，不涉及设盲或紧急破盲。

2021年6月16日星期三（第2天翻译282个词）

All patients met the diagnostic criteria for COVID-19 according to the National Health Commission of China (Trial Version 5). Following established clinical guidelines for the diagnosis and treatment of COVID-19, patients can be classified as mild, common, severe, or critical.53,62,63 Only severe and critically ill COVID-19 patients were included in the present study. Severe patients were defined as those with respiratory distress, respiratory rate ≥30 breaths/min; resting oxygen saturation ≤93%; or arterial blood partial pressure of oxygen (PaO2)/fraction of inspiration O2 (FiO2) ≤300 mmHg (1 mmHg = 0.133 kPa). Critical COVID-19 patients were defined as those with respiratory failure who required mechanical ventilation, those who had experienced shock, or those for whom a combination of organ failures necessitatedmonitoring and treatment in the intensive care unit (ICU). Exclusion criteria for this trial were as follows:

(1) severe liver disease;

(2)long-term hemodialysis and severe renal impairment or continuous renal replacement therapy;

(3) comorbidities that might affect the ability of researchers to determine

drug efficacy (mainly malignant tumors, active tuberculosis,interstitial pneumonia, and pulmonary heart disease);

(4) treatment with glucocorticoid medications or other immunosuppressive drugs for longer than 2 weeks;

(5) history of major surgery within 30 days of screening or presence of an unhealed surgical wound;

(6) allergy to any active/inactive ingredients in the study drug;

(7) pregnant or breastfeeding;

(8) previous history of prothrombotic events (venous thromboembolism/stroke);

(9) other circumstances judged by an investigator to preclude participation.

These “other circumstances” leading to exclusion from the study included serious AEs for which the investigator judged that the risk of continuing to participate in the trial was too great, as well as the use of other treatments,without authorization and against medical advice, that could have affected the evaluation. These exclusion criteria followed the National Health Commission of China (Trial Version 5). If a patient met all the inclusion or exclusion criteria, he or she was then enrolled in the experimental group (MSC infusion + concomitant medications) or the control group (concomitant medications).

根据中国国家健康委员会（试用版5）所有患者均要符合新冠诊断标准。根据新冠诊断和治疗的建立的临床指导，患者被分为轻度、普通、重症、危重。只有严重和危重新冠患者被包含在这个研究中。重症患者被定义根据这些呼吸困难，呼吸频率大于30次/分钟，休息时氧气饱和度小于等于93%，或者什么的氧气血液部分压力动脉血氧分压(PaO2)/吸入氧分数(FiO2) 小于等于300 mmHg (1 mmHg = 0.133 kPa)。危重新冠患者被定义为需要借助仪器通气呼吸失败衰竭者，经历过休克，在ICU中需要监测和治疗器官衰竭组合患者。

试验排除标准如下：

严重肝脏疾病

长期什么血液透析和严重的什么影响肾脏损害或者不断的什么肾脏替代治疗

什么可能影响研究者决定药效的能力（重要的是智力问题恶性肿瘤，活跃的什么活动性肺结核，孕妇间质性肺炎，和肺心脏疾病）

超过两周使用糖皮质激素药物或者免疫抑制药物

筛选30天内有大手术史，或者存在未愈合的手术伤口

对研究药物中任何活性/非活性成分过敏

怀孕或母乳喂养

血栓事件史（静脉血栓栓塞/中风）

通过研究者判断排除参与的其他的情况

这些其他情况导致研究中排除的包括调查者判断为继续参与试验风险非常大的严重不良事件，未经授权使用其他治疗和违背药物说明，影响药物评估。这些排除标准严格遵循中国国家健康委员会（试行版5）如果一个患者满足所有的排除标准，他或她会被登记进试验组。（MSC注射+伴随用药或对照组（伴随用药））

2021年6月17日星期四（第3天翻译331个词）

2.2 Stratification of disease treatment and concomitant medications

Patients were enrolled and admitted between January and April 2020 at either Renmin Hospital of Wuhan University or the First Affiliated Hospital, College of Medicine,Zhejiang University. A clinical plan was designed for each patient based on their clinical needs. Since the patients

in this clinical study were either severe or critical, concomitant medications were allowed, and the details of all additional treatments were recorded. Drugs that were required to treat other diseases were allowed if an investigator judged that the safety and efficacy of the study medications would not be affected. However, the type and dose of the medications were kept as consistent as possible while prioritizing patient safety. For any concomitant medications or other treatments, detailed medication information was recorded on the original medical record and the eCRF.Of the 44 patients enrolled in this study, 36 were from Wuhan University People’s Hospital, including 20 severe patients and 16 critically ill patients. The remaining eight patients were enrolled from the First Affiliated Hospital,College of Medicine, Zhejiang University including six severe patients and two critically ill patients. Due to the high risk of mortality, patients were given the choice as to which group they were placed in, and 26 patients chose to receive the experimental treatment along with the comprehensive treatment, while 18 patients chose to be included in the control group and receive only the comprehensive treatment. The standard of carewas consistent between the two hospitals.

2.2 疾病治疗和伴随用药的分层

从2020年1月到4月，在武汉大学人民医院和浙江大学医学院附属医院患者被安排入组和确认。基于他们的临床需求为每一个患者设计临床计划。无论是重症还是危重症的临床研究患者，合并用药都被允许，所有的其他治疗详细信息都要被记录。如果研究者判断对研究药物的安全性和有效性没有影响，允许使用治疗其他疾病的药物。但是，在优先考虑患者安全性下尽可能保持药物的类型和剂量一致。对于任何联合用药和其他治疗，详细的药物信息被记录在原始的药物记录和eCRF中。

研究中入组的44例患者，36例来自武汉大学人民医院，包括20例重症患者和16例危重症患者。其余的8例患者来自浙江大学医学院附属医院，包括6例重症患者和2例危重症患者。由于高风险死亡率，病人被给与机会选择他们被参与的组，26个病人选择在综合治疗接受试验治疗，18个病人选择在对照组仅仅接受综合治疗。在两家医院保持护理标准一致。

2.3 MSC preparation, cell transplantation, and subsequent observation

Allogeneic, menstrual blood-derived MSCs (no.SC0100919001, no. SC0100919004, and no. SC0100919005 provided by Innovative Precision Medicine (IPM) Group,Hangzhou, China) were obtained from three healthy emale donors (age range, 20-45 years), and the volunteers were educated and provided signed, informed consent before donation, as described in previous studies.55,64 The donation protocol was authorized by the Ethics Committee of Zhejiang University. The mononuclear cells within the menstrual blood were collected and purified, and cell viability was measured prior to seeding for cell culture according to the staining with trypan blue solution (Thermo Fisher Scientific, No. 15250061). MSCs were passaged at 70-80% confluence. Surface-labeled molecules (including CD29, CD34, CD45, CD73, CD90,CD105, CD117, and HLA-DR) were measured using flow cytometry (CytoFLEX LX Flow Cytometer, Beckman) and detailed procedures were described in a previous study.65 Supporting information Table S1 includes detailed information on the antibodies used for surface marker analysis. Detection of the differentiation potential ofMSCs into the osteogenic differentiation medium, chondrogenic differentiation medium, and adipogenic differentiation medium A and B (Cyagen Biosciences) and their detailed information has been reported in a previous study.66 PCR analysis was used to check the ACE2 expression level of the MSCs. The detailed procedures for PCR analysis have been described in a previous study.67 Briefly, cell samples were homogenized in 1 mL of RNAiso Plus (9108, Takara,Japan) to isolate total RNA according to the manufacturer’s instructions. RNA was then reverse-transcribed into cDNA using a FastQuant RT Kit with gDNase (KR106,Tiangen Biotech, China). Then a total of 10 μL sample (1μL cDNA, 5 μL PCR Mastermix [KT201, Tiangen Biotech],1 μL forward primer, 1 μL reversed primer, and 2 μL ddH2O) was used for PCR with 30 cycles. Supporting information Table S2 includes the primer sequences for PCR analysis. The resulting cryopreserved MSCs were shipped frozen to the hospitals in a validated liquid nitrogen (≤−135C) dry shipper. Before their use, MSCs were resuspended in Plasma-Lyte 148 at room temperature by a local laboratory with a specialized cellular therapy center, and the control group was also administered the same volume of Plasma-Lyte 148. The viability of MSCs for the three donors should be >90%, which was a criterion for use in the clinical study guided by the Innovative Precision Medicine (IPM) Group. MSCs were used for treatment at the fifth passage, as described in our previous report.66 Twenty-six patients received MSC transplantation, and18 patients received all treatments exceptMSC transplantation.Complete case enrollment details and disease severity frequencies of the 44 COVID-19 patients included in the present study can be viewed in Table 1. Each COVID-19 patient in the experimental group used the MSC sample from one donor for all three treatment injections. Doctors observed hemodynamic and respiratory parameters at the bedside forat least 1 h toensure that eachpatientwas stable before MSC transplantation. Then, the MSC infusion was initiated using a standard blood filter tube. A researcher remained at each patient’s bedside to continuously monitor the patient for any adverse reactions during the 24 h following treatment. Based on data fromstudies on the use of MSCs to treat H7N9-induced ARDS,55 MSCs were administered as three infusions totaling 9 × 107 MSCs every other day (day 1, day 3, and day 5). Each infusion contained 3 ×107 cells resuspended in 500 mL saline solution and was performed at a speed of 30-40 drops/min for about 15 min,followed by a speed of 100-120 drops/min for 2 h to retain

MSC vitality.

2.3 MSC的制备，细胞移植，和连续观察

正如研究前的所述，同种异体、经血来源MSCs的获取来自三名健康女性捐献者（年龄范围20-45岁），并且这些志愿者被教育，在捐献前提供签署知情同意。这些捐赠协议被浙江大学伦理委员会批准。经血中的单个核细胞被收集和净化，并且根据保持蓝色情况细胞繁殖被测量加速，在接种细胞培养前根据盼蓝溶液染色测量细胞活性。（to表示方向和目的，细胞培养接种是什么意思？暂时没有得到答案）。表面标记分子被测量使用流式细胞术，在研究前详细过程被描述。支持表S1信息包含在使用表面标记分析的抗体上详细信息。不同的MSCs潜在保护进入不同的药物，检测MSCs向成骨分化培养基、成软骨分化培养基和成脂分化培养基A和B的分化潜能，并且他们详细的信息在研究前被报道（differentiation分化，medium错误翻译medicine，本意是介质，传媒）。PCR分析被用来检查MSCs的ACE2表达水平。PCR分析详细的过程在研究前被描述。简单说，根据制造商说明样本细胞在1 mL 的RNAiso Plus中匀浆为了分离总RNA（homogenized本意是同质化）。使用具有gDNase 的FastQuant RT Kit将RNA重复转录为cDNA。10 μL样本总量用于PCR，30个循环。支持信息表S2包含PCR分析引物序列。MSCs的冷冻保存结果在医院验证过的液氮干货机中风干了水分。MSCs的冷冻保存结果使用验证过的液氮干货运输工具冷冻运送到医院（to hospitals如何翻译，主要是ship错位翻译为风干，本意是船只，船的用途是运输货物，所以也有运输的意思）。在使用之前，MSCs在室温下通过特别专门的细胞治疗中心当地检查实验室被暂停重新悬浮在Plasma-Lyte 148中，并且对照组也被管理在Plasma-Lyte 148相同溶剂中（resuspended重新悬浮）。三个捐献者MSCs的活性存活率应该大于90%，在临床研究指南中通过IPM小组紧急使用这是通过IPM小组指导的临床研究中使用标准（viability翻译为存活率，criterion翻译错误，等于standard，which is如何翻译）。正如我们报告前沿描述，MSCs在第5环节第5代被使用治疗（the fifth passage，第五代，passage要根据语境翻译，页数，段，章节）。

26个患者接受MSC移植，18个患者接受除了MSC移植外所有治疗。完整的病例入组信息和包含在目前研究中44例COVID-19反复严重疾病患者被展示在表1中，法规目前研究中44例COVID-19患者的完成病例登记详细信息和疾病严重程度频数可以在表1中查看（severity和frequencies翻译错误，严重程度和频数）。在试验组的每一个COVID-19患者使用了来自一个捐献者的MSC样本进行了三次治疗注射。医生在旁边至少1个小时观察血液动力学和呼吸参数以确保每一个患者在MSC移植前稳定。然后MSC开始被注射使用标准血液过滤管。一个研究者保持在每一个病人旁边为了在24小时内跟踪治疗监视病人任何不良反应。基于从研究中使用MSV治疗H7N9-induced ARDS的数据, MSCs注射三次给药总量9 × 107 MSCs，间隔一天（第1，第3，第5天）。每次注射包含3 ×107 细胞重新悬浮在500ml盐水溶液中，以30-40滴/秒的速度进行大约15分钟，然后100-120滴/秒速度进行2个小时保持MSC活性。 

（2021年6月24日星期四翻译575个单词）

2.4 Biological measurements and clinical evaluation indices

Laboratory measurements of blood test results, liver function

markers, and inflammatory indicators were carried out at the Medical Inspection Center of the First Affiliated Hospital, College of Medicine, Zhejiang University and Renmin Hospital ofWuhan University. Factors which were investigated for having an association with therapeutic

features or outcomes were as following: (1) baseline characteristics including age, underlying conditions, and clinical symptoms; (2) laboratory data and chest computed tomography (CT) data; and (3) concomitant medications for basic therapy, symptomatic treatment, antiviral treatment,antibacterial treatment, hormone therapy, intestinal

microbial state regulators, extracorporeal blood purification technology, traditional Chinese medicine treatment (including Jinhua Qinggan granules, Lianhua Qingwen capsules [granules], and Shufeng Detoxification capsules[granules]), etc.

The objective of the current study was to evaluate the safety and efficacy of MSC transplantation as a treatment for COVID-19. The primary endpoint of the analysis was survival rate from January to April 2020, and this was based both on the survival of a full analysis set (FAS) and a per protocol set (PPS). The FAS, which was also the effectiveness analysis set, consisted of all 44 subjects who were initially enrolled in this study, which included 26 patients in the experimental group and 18 patients in the control group. Since two cases were initially included in the study who violated the exclusion criteria, the remaining 42 subjects were included in the PPS, which included 24 patients in the experimental group and 18 patients in the control group. The secondary endpoints for this study included measures of effectiveness and tolerability,primarily including negative viral test results, time taken to recover from all symptoms, change in chest CT results, change in indicators of inflammation, change in oxygenation index, occurrence of shock, incidence of multiple organ failure, length of hospital stay, number of days in the ICU, and respiratory support status. Before and after the MSC infusion, patients were tested using several laboratory indices, including those related to hematuria routine, liver and kidney function, coagulation function,vital signs, physical examination, oxygenation (FiO2,peripheral oxygen saturation [SpO2], oxygen saturation[SaO2], and PaO2), and inflammatory factors (including interleukin [IL]-6 and C-reactive protein [CRP]). Figure 1 shows the CONSORT diagram (Figure 1A) and detailed infusions within 1 month (Figure 1B) for this clinical study.Safety wasmeasured by the frequency of treatment-related adverse events (AEs) and through careful surveillance of laboratory indices. Clinical datawere obtained on each day of MSC infusion (days 1, 3, and 5) as well as on days 7, 14,and 30 of the posttreatment period.

2.4生物衡量和临床评估标准

血液测量结果、肝功能指标、炎症指标的实验室检查在浙江大学医学院第一附属医院和武汉大学人民医院的医学检查中心进行。与治疗特征和结局相关的因素调查调查因素如下：

基线特征，包括年龄，基础疾病，临床特征；

实验室数据和胸部CT数据

基础治疗，对症治疗，抗病毒治疗，抗菌治疗，激素治疗、

肠道微生物状态调节剂、体外血液净化技术、中药治疗等合并用药。

这个研究的目的是评估MSC移植治疗COVID-19的安全性和有效性。分析的基础结局是2020年1月到4月的存活率，这是基于全分析集存活和安全性分析集的存活率。全分析集也是有效性分析集，与研究中最初入组的44例患者一致，包含26例试验组患者和18例对照组患者。由于最初的2例患者被包含在研究的排除标准中（violated什么意思，two cases were included in the study who violated the exclusion criteria这句话的主句是什么，我判断included是主句，后面有从句引导词），由于违反了排除标准的两个病例最初被纳入研究中，所以剩下的42例患者被纳入PPS中，包括24例试验组患者和18例对照组患者。研究的次要目的包含有效性和容忍度耐受性的测量，基础主要包含阴性生命病毒检测结果（viral错误翻译为生命，生命是vivid），所有症状恢复的所需时间，胸部CT结果变化，什么的炎症指标变化，什么的氧合指数变化，震动休克的发生，多组织失败多器官衰竭的发生率，住院时长，ICU天数，呼吸支持稳定状态。MSC注射前后，使用多项实验室指标对患者进行检测，包括什么血尿常规，肝肾功能，什么凝血功能，生命体征，体格检查，氧合，氧气什么血氧饱和度，和炎症因子等相关指标。图1显示了临床研究的CONSORT图（图1A）和1个月内的详细注射。安全性测量使用与治疗相关的不良事件频率和通过监测实验室指标。MSC注射的每一天（第1、3、5天）和治疗后第7、14和30天获取临床数据。

（2021年6月25日星期五翻译413单词）

2.5 Statistical analysis

To compare the experimental and control groups, χš or Fisher’s exact tests were used, as appropriate, for both the FAS analysis and the PPS analysis. The FAS analysis included 44 patients, while the PPS analysis included a subset of 42 patients. The Kaplan–Meier method was utilized

to analyze the survival time of discharged patients,and two-sided 95% exact confidence intervals (CIs) were calculated using the log-rank test. We also calculated a Cox proportional hazards model to assess factors affecting survival, adjusting for gender, and age as covariates.For the length of hospitalization and ICU stay, aWilcoxon rank sum testwas used to compare the differences between groups. For analysis of inflammatory indices, (including CRP and IL-6) and oxygenation indices (FiO2, SpO2, SaO2,and PaO2), Wilcoxon rank sum tests were used comparing the experimental group before and after the MSC infusion.Statistical analysis was carried out using SAS9.4. P value < .05 was considered as statistically significant.

2.5 统计分析

根据试用性，对全分析集和PPS分析集比较实验组和对照组，使用卡方或者Fisher精确检验；全分析集包括44例患者，而PPS分析集包含42例患者的子集。这个Kaplan–Meier的方法是用来分析未改变的患者的生存时间，95%双侧精确置信区间使用对数秩检验。为了评估影响生存的因素我们也计算一个COX风险比例，调整性别和年龄作为协变量。对于住院时间和ICP停留时间，使用Wilcoxon秩和检验比较组间不同。为了分析什么验证指数和氧气吸入氧和指数Wilcoxon秩和检验用来比较试验组MSC注射前和注射后。统计分析使用SAS9.4，P值小于0.05被认为有统计学意义。

2021年6月17日星期四（第3天翻译155个词）

3 RESULTS

3.1 Patient characteristics and MSC treatment

The viability of MSCs for the three donors was >90%(91% for SC0100919001 and SC0100919004, and 92% for SC0100919005). MSCs strongly expressed CD29, CD73,CD90, and CD105; and MSCs were negative for CD34,CD45, CD117, and HLA-DR (Supporting information Figure S1). Furthermore, MSCs can be successfully induced into osteogenic, adipogenic, and chondrogenic cells through the specific medium, and the representative picture for each kind of differentiated cells is shown in Supporting information Figure S2. A representative electrophoretogram with two pairs of primers is shown in Supporting

information Figure S3. MSC ACE2 expression was negative according to PCR analysis, with ddH2O as a negative control and 293T cells as a positive control.Twenty-six patients were included in the experimental

group and treated with MSC transplantation and combination therapy. Among these, 16 (61.5%) were classified as severe and 10 (38.5%) were classified as critical.Eighteen patients were included in the control group and received only combination therapy. Among these, 10(55.6%) were classified as severe and 8 (44.4%) were classified as critical (Table 2). The experimental group contained 17 males (65.38%) and nine females (34.62%), while the control group contained 13 males (72.22%) and five females (27.78%). The mean and median age of the experimental group was 58.31 ± 12.49 and 57.50 years, respectively, while the mean and median age of the control group was 61.11 ± 11.03 and 64.00 years, respectively. There were no statistically significant differences with regards to gender or age (P > .05). There were no significant differences

(P > .05) in clinical symptoms (including fever, expiratory dyspnea, sore throat, diarrhea, and chest tightness) between the experimental group and the control group during the baseline period (Table 2). The symptom of cough showed a significant improvement following MSC infusion on day 1 (P = .037) compared to that of the control group, but no differences were found at other times points. During the period of MSC infusion (days 1, 3,and 5) and the post-treatment period (days 7, 14, and 30), the symptoms of fever, cough, sore throat, diarrhea, and chest tightness were not significantly different (Table 2).There was a significant improvement in expiratory dyspneawhile undergoingMSCinfusion on day 1 (P=.016), day 3 (P = .040), and day 5 (P = .031) compared to the control group (Table 2), but there were no significant differences on day 7 (P = .631), day 14 (P = .635), or day 30 (P = 1.000).

3.1患者特征和MSC治疗

对于三个捐献者MSCs的存活率达到90%（SC0100919001 和SC0100919004是91，SC0100919005达到92%）。

MSCs的强烈表达CD29, CD73,CD90, CD105; MSCs对 CD34,CD45, CD117, HLA-DR呈阴性（支持信息表S1）。

更重要的是此外，MSCs通过特殊的药物特定的培养基可以成功的进入这些细胞诱导成成骨细胞、脂肪细胞和软骨细胞；每一个分化的细胞代表图片在显示在支持信息图2中。一个带着两双什么的两对引物的代表性电泳图显示在支持信息图S3中。在ddH2O作为阴性对照和293T 细胞阳性对照下，根据PCR分析MSC ACE2的表达是阴性。

26例患者包括在试验组和MSC移植以及合并治疗；在这些里面，16例（61.5%）被分为重症和10例（61.5%）被分为危重症。18例患者在对照组，且只接受合并治疗；在这些里面，10例（55.6%）被分为重症，8例（44.4%）被分为危重症（见表2）。试验组中包括17例男性（65.38%）和9例女性（34.62%），对照组中包括13例男性*（72.22%）和5例女性（27.78%）。试验组年龄的平均值和中位数分别是58.31 ± 12.49 和57.50 岁；对照组的年龄的平均值和中位数分别是61.11 ± 11.03 和 64.00 岁。关于性别或年龄没有显著统计学差异（P>0.05）。在研究初期试验组和对照组在临床症状上（包括发烧，呼吸性呼吸困难，咽喉疼痛，什么腹泻，胸部胸闷）没有显著统计学差异（表2）。咳嗽的症状在MSC注射的第一天与对照组相比有显著提高（P=0.037），但在其他时间点没有差异发现。在MSC注射期间（第1、3、5天）和注射治疗期后（第7、14、30天），发烧、咳嗽、咽喉痛、腹泻、胸闷这些症状没有显著差异（见表2）。当经过MSC注射第1天（P=0.016）、第3天（p=0.04）、第5天（p=0.031）与对照组相比呼吸性呼吸困难有显著提高，但在第7（P=0.631）、第14（p=0.635）、或第30天（p=1.000）没有显著性差异。

3.2 Analysis of the use of concomitant medications

As per the principles of treatment for severe and critically ill COVID-19 patients, combination drugs were allowed to treat the patients as effectively as possible. Concomitant medications were mainly used for symptomatic treatment,antiviral treatment, antibacterial treatment, hormone therapy, intestinal microbial state regulation, extracorporeal blood purification, traditional Chinese medicinal treatment, and basic disease treatment, among others.As shown in Table 3, there were no statistical differences in the types of combined medications between the two groups (P > .05). However, there were intragroup differences with regard to concomitant treatment using extracorporeal blood purification both in the experimental group (P < .001) and in the control group (P = .015). Specifically,concomitant treatmentwith an extracorporeal blood purification system was employedmore often for critically ill patients than for severe patients in both the experimental and the control groups.

3.2 使用合并用药分析

对于重症和危重症COVID-19患者每一个治疗原则，在尽可能有效性的情况下合并要是被允许治疗病人的。合并用药主要用于对症治疗、抗病毒治疗、抗菌治疗、激素治疗、肠道微生物状态调节，体外血液净化，中药治疗、基础疾病治疗、以及其他的。如表3所示，在两组间合并用药没有统计学差异（P>0.05）。然而，这里关于使用体外血液净化合并治疗有组间差异，在试验组（P<0.001）对照组（P=0.015）。值得注意的是，不管是试验组还是对照组体外血液净化合并治疗的应用，危重症患者一般多于重症患者。

3.3 Assessment of the efficacy of MSC infusion after 1-month follow-up

The primary endpoint for this studywas the survival rate of severe and criticalCOVID-19 patientswith or without MSC infusion. Treatment efficacy was assessed throughout the study period both in the FAS and the PPS. As shown inTable 4, the survival rate for the experimental group was 92.31% (24/26) for the FAS, while the survival rate for the control group was 66.67% (12/18). This difference in survival rate was statistically significant (P = .048). Similar results were obtained when the PPS was analyzed separately.The survival curves for the FAS and the PPS are presented in Figure 2A, B, respectively. Our results suggest that MSC infusion exerts a positive therapeutic effect on the survival rate of severe and critically ill COVID-19 patients.

For severe patients, a Cox proportional hazards model of the FAS showed that the hazards ratio (HR) for the experimental group relative to the control group was .10 (95% CI, 0.00-1284.41), which was not statistically significant (P = .437; Supporting information Table S3). Using gender and age as covariates, the adjusted HR (95% CI) was .00 (0.00–∞), which was also not statistically significant (P = .970). For critically ill patients, the HR (95% CI) for the experimental group relative to the control group was .34 (.06-1.88; P = .218), and the adjusted HR (95% CI) with gender and age as covariates was .11 (.01-.89), which was statistically significant (P = .039). Similar results were obtained when the PPS was analyzed (Supporting information Table S4): the adjusted HR (95% CI) with gender and age as covariates was .12 (0.00–.95), which was statistically significant (P = .047). Thus, our results suggest that

MSC transplantation increases survival more for critically ill patients than for severe patients when adjusting for gender and age.

The secondary endpoints for this study mainly included negative viral test results, time taken to recover from all symptoms, length of hospital stay, number of days in the ICU, occurrence of shock, incidence of multiple organ failure, change in chest CT results, and respiratory support status. Detailed results are presented in Table 5. The average time taken to recover from viral infection, as indicated by a negative viral test, was 15.75 ± 13.71 and 18.31 ± 9.86 days for the experimental and the control groups, respectively. Statistical analysis showed that these differences were not significant (P = .251). The average time to improvement for the experimental group and the control groupwas 3.00 ± 3.05 and 8.80 ± 10.77 days, respectively,meaning that the average time taken to improve for the experimental group was 5.8 days shorter than that for the control group, and this difference was statistically significant (P = .049), indicating that MSC infusion was able to shorten the time required for treatment. There was no significant difference in either the length of hospital stay or in the number of days in the ICU (both P > .05), and there was also no significant difference in the occurrence of shock or multiple organ failure between the groups (both P > .05). Further, there was no statistical difference in the use of respiratory support between the two groups (Table 6). One month after MSC infusion, 20 patients in the experimental group and 12 patients in the control group underwent chest CT by three respiratory physicians who were blinded to the treatment group; 17 (85.00%) patients in the experimental group had improved,

while 3 (15.00%) patients showed no significant change. In contrast to the experimental group, six (50.00%) patients in the control group had improved, while the other six (50.00%) showed no significant change. Figure 3 shows representative CT scans documenting lung improvement at various time points for both the control and the experimental group. The difference in the improvement of chest imaging results in the first month after MSC infusion was significant. Representative CT images of both groups at post-treatment days 7, 14, and 30 are shown in Figure 3. Together, these results suggest that the relative improvement rate was higher for the experimental group during the 1 month after MSC infusion than it was for the control group.

Additionally, inflammatory indices (including CRP and IL-6) and oxygenation indices (FiO2, SpO2, SaO2, and PaO2) were analyzed before and after MSC infusion (Table 7), and there were no significant differences in CRP (P = .486), IL-6 (P = .375), FiO2 (P = .174), and SaO2 (P = .068). Interestingly, SpO2 was significantly improved following MSC infusion, from 94.72 ± 3.4% before treatment to 96.04 ± 5.93% after treatment (P < .001). Moreover,PaO2 was significantly improved following MSC transplantation,from 78.89 ± 25.86 mmHg before treatment to 95.62 ± 39.49 mmHg after treatment (P = .015).

3.3评估MSC注射一个月后追踪的有效性

研究主要结局是重症和危重症COVID-19患者注射MSC和没有注射的存活率。治疗有效性基于研究期的FAS和PPS集评估。如表4所示，在FAS中试验组的存活率是92.31%（24/26），对照组存活率是66.67%（12/18）。在存活率的差异具有统计学显著意义。在PPS分析中获取的结果一致。对于FAS和PPS存活周期分别见数据2A,B。我们的结果表明MSC注射在重症和危重症COVID-19患者存活率上有积极的治疗影响。

对重症患者，FAS的COX风险比例模型显示试验组相对于对照组的HR是0.1（95%CI，0.00-1284.41），无统计学显著意义（P=0.437.支持信息表3）。使用性别和年龄作为协变量，调整后的HR（95%CI）是0.00（0.00–∞），也没有统计学显著意义（p=0.970）。对于危重症患者，试验组相对与对照组的HR是0.34（0.06；P=0.218），使用性别和年龄作为协变量调整后HR（95%CI）是0.11（0.01-0.89），是有统计学显著意义的（P=0.039）。PPS集分析获取的结果相同（支持信息表4）；性别和年龄作为协变量调整后HR（95%CI）是0.12（0.00-0.95），有统计学显著意义（P=0.047）。因此，我们的结果表明当调整性别和年龄，危重症患者比重症患者MSC移植增加存活。

研究的次要结局包括阳性病毒检测结果、所有症状恢复花费时间，住院时长，ICU天数，休克的发生，多组织衰竭发生率，胸部CT结果的改变，呼吸支持状态。详细的结果显示在表5中。从病毒感染到恢复耗费的平均时间，通过阳性病毒检测作为发生，试验组和对照组分别是15.75 ± 13.71和18.31 ± 9.86天。统计分析显示差异性没有显著意义（P=0.251）。试验组和对照组改善的平均时间分别是3.00 ± 3.05 和 8.80 ± 10.77天，意味着得到改善平均时间试验组比对照组短5.8天，这个差异是有统计学意义的（P=0.049），表明MSC注射是能够缩短治疗所需时间的。住院时长和ICU天数（P值都>0.05）都没有显著差异，且休克和多组织衰竭的发生也是没有显著性差异的。还有，两组间使用呼吸支持也没有统计学差异（见表6）。MSC注射后一个月，试验组20例患者和对照组12个患者在对照组经历胸部CT通过三种对治疗组设盲的物理呼吸。17（85%）患者有改善，然而3（15%）显示没有显著变化。与试验组相比，对照组6（50%）患者得到改善，当其他6例显示没有显著改变。表3展示了代表性CT扫描，记录在对照组和试验组的多时间点的肺部改善。在MSC注射的第1个月胸部成像结果改善的差异是有显著意义的。在治疗后第7、14和30天两组代表性CT成像被显示在表3中。总之，这些结果表明，在MSC注射后1个月期间相关改善率试验组比对照组更高.

另外，在MSC注射前后炎症指数(including CRP and IL-6)和氧合指数（FiO2, SpO2, SaO2, and PaO2）被分析（见表7）.在CRP和 SaO2上没有显著性差异(P = .486), IL-6 (P = .375), FiO2 (P = .174), (P = .068)。有趣的是，MSC注射后SpO2有显著提升，从治疗前的94.72 ± 3.4%到治疗后的96.04 ± 5.93%（P < .001）。甚至，PaO2在MSC移植后有显著增加，从治疗前78.89 ± 25.86 mmHg增加到治疗后95.62 ± 39.49 mmHg（P=0.015）。

（2021年6月29日星期二翻译784个词）

3.4 Presence of AEs following treatment

The severity of each AE related to COVID-19 infection was graded from 1 to 5 for both the experimental group and the control group, and a summary of all AEs experienced by the 44 COVID-19 patients included in the current study are presented in Supporting information Table S5. According to the statistical analysis, 76.92% (20/26) of the patients experienced a total of 56 AEs in the experimental group, including 40 AEs of grade 1, 6 AEs of grade 2, 3 AEs of grade 3, 4 AEs of grade 4, and 3 AEs of grade 5. In contrast, 100.00% (18/18) of the patients experienced a total of 59 AEs in the control group, including 39 Aes of grade 1, 5 AEs of grade 2, 3 AEs of grade 3, 7 AEs of grade 4, and 5 AEs of grade 5 (Supporting information Table S5). During the study period, no patients in either the experimental group or the control group showed Aes that necessitated withdrawal from the study. A detailed analysis of the AEs observed in the experimental group and the control group is presented in Table 8. As shown in Table 8, 10 of the 56 AEs observed in the experimental group were grade 3 or higher, while 15 of the 59 AEs observed in the control group were grade 3 or higher. Except for a difference in the incidence of high blood pressure between the two groups, there were no significant differences (P > .05) between the groups for any AEs related to the measured clinical indices including the blood test results, liver function markers, blood lipid levels,renal function,myocardial enzymes, electrolyte disturbances,and clinical symptoms. High blood pressure was observed in two (3.57%) patients in the experimental group and six (10.18%) patients in the control group (P = .048).In summary, the frequency of each AE was statistically similar between the two groups, except for the AE related to high blood pressure, which was more common in the control group. Further, the experimental group showed a lower incidence of AEs (76.92%) than the experimental group (100.00%), but the difference was not statistically significant. Together, these results suggest that the MSC infusion protocol used in this study showed good safety outcomes.

3.4 治疗中AEs情况

在试验组和对照组中，每一个与COVID-19感染相关AE的严重程度被等级划分从1到5，通过本研究的44例COVID-19患者经历的所有Aes的总和被显示在支持信息表S5中。根据统计分析，在试验组中76.92% (20/26)的患者经历了56次AEs，其中有40个AE是等级1，3个AE是等级2，3个AE是等级3，4个AE是等级4，3个AE是等级5。相比之下，对照组100.00% (18/18)的患者经历了59次AEs，包括39次AE等级1，5次SE等级2（支持信息表5）。在研究期间，无论是试验组还是对照组没有患者显示由于AE需要从研究中退出试验。在试验组和对照组中一个观察AE的详细分析显示在表8中。如表8所示，在试验组中观察的56次AEs中的10次是等级3或更高，然而对照组中观察的59次AEs中的15次是等级三或更高，除了在两组中高血压不同，，这里没有显著性差异（P>0.05），在组中任何与AE相关的临床测量指标，包括血液检测，肝功能指标，血脂水平，肾功能，心肌酶，电解质紊乱，临床症状。高血压被观察到有2例患者（3.57%）在试验组，有6例患者（10.18%）在对照组（P=0.048）.总的来说，在两组中每一个AE的频数具有统计相似性，除了与高血压相关的AE，在对照组有更多的共同点。进一步来说，试验组的AEs（76.92%）比对照组的（100%）显示更低的发生率；但是这个差异无统计学意义。总之，这个结果表明，在研究中使用MSC注射方案显示有更好的安全性结局。

（2021年6月29日星期二翻译374个词）

4 DISCUSSION

The initial symptoms of COVID-19 are often fever, cough,sputum, and shortness of breath. These in turn can lead to dyspnea, ARDS, lung injury, shock, and eventual multiple organ failure.68,69 An autopsy study by Xu et al reported that a deceased COVID-19 patient showed a large amount of sputum, presumably causing severe ARDS, as well as a large number of inflammatory factors in the lung tissue.13 This suggests that effective treatment ofARDS and prevention of multiple organ failure is a key strategy in preventing mortality in COVID-19 patients. Severe ARDS causes breathing difficulties, and it has been suggested that resolving

breathing difficulties in COVID-19 patients in a timely manner may make it is possible to inhibit COVID-19 progression. Interestingly, we found that patients treated with MSCs experienced immediate and dramatic relief from breathing difficulties associated with COVID-19 on day 1 (P = .016), day 3 (P = .040), and day 5 (P = .031) compared with the control group. Further, our results show that both SpO2 and PaO2, indices associated with oxygenation levels, were significantly improved after MSC infusion. These results further support the use ofMSC infusion

as amethod to combat ARDS and expiratory dyspnea, particularly for critically ill COVID-19 patients.

Multiple complications of the COVID-19 epidemic make it difficult to fully treat patients with this disease. Many interventions in China and around the world have proven effective to reduce the epidemic and prevent the virus from continuing to spread.5,70–74 Although effective social distancing can mitigate the virus’s persistence, treating COVID-19 is also an important strategy toward ending the current pandemic.

X-ray and chestCT imaging results ofCOVID-19 patients in the ICU have been shown to reveal the presence of pneumonia,known as novel coronavirus pneumonia. These imaging results reveal bilateral, multilobular involvement as well as subsegmental consolidation.75 In the present study, we observed a statistically significant difference in the rate of improvement of chest CT results in the first month after MSC infusion. A total of 85.00% of patients with MSC treatment showed improved chest CT results, compared with only 50.00% of patients in the control group. These results provide further evidence for the efficacy of MSC infusion.

4讨论

COVID-19初期的症状是发烧，咳嗽，咳痰、呼吸短促。这些反过来会导致呼吸困难、ARDS，肺损伤，休克，最终的多组织衰竭。XU等人的尸检报告称一名死于COVID-19患者显示大量的什么痰，造成推测为严重ARDS，和肺部什么组织中大量的炎症因子。这表明ARDS的有效治疗和阻止多组织衰竭是阻止预防COVID-19患者死亡的钥匙关键策略。严重的ARDS造成呼吸困难，它已经表明及时解决COVID-19患者呼吸困难使抑制COVID-19发展成为可能。有趣的是，我们发现接受MSCs患者治疗在第1天（P=0.016），第3天（P=0.040），第5天（P=0.310），与对照组相比，与COVID-19相关的呼吸困难经历什么和什么立即和显著的缓解。而且，我们结果显示与氧合水平闲逛指标SpO2 和 PaO2，在MSC注射后有显著提高。这些结果更加支持MSC注射使用作为一种对抗ARDS和呼气型呼吸困难的方法，尤其是对危重症COVID-19患者。

COVID-19“的什么多复杂的”流行的多种并发症让完全治疗这种疾病患者更加困难。”大多数”中国和世界”研究者”的很多干预措施已被证明可以有效减少流行和“阻止“防止病毒继续传播”已经证明有效”。虽然有效的社会社交距离可以”减少病毒传播“减轻病毒的持久性，但是治疗COVID-19也是结束当前疾病流行重要的策略。

COVID-19患者在ICU的X射线和胸部成像结果显示“什么“存在肺炎，即“新冠病毒的什么出名”新型冠状病毒肺炎。这些成像结果“什么，什么，和什么”显示双侧，多小叶受累以及亚节段实变。在本研究中，我们观察到在MSC注射后第一个月胸部CT结果的改善率有统计学显著差异。接受MSC治疗患者的85%显示胸部CT有改善，相比之下对照组只有50%的患者表现出改善。这些结果为MSC注射有效性提供了“更多”进一步证据。

Currently, an effective vaccine would be the best way to combat SARS-CoV-2 infection, and many groups have presented preliminary basic and clinical data related to vaccine development.24,25,76–78 However, assessing the safety and efficacy of any vaccine will take a relatively long period of time. Apart from targeted vaccine development, other therapeutic strategies are being developed in the race against time to end the global pandemic. Remdesivir, an inhibitor of the viral RNA-dependent, targets nascent viral RNA chains, resulting in premature termination of the viral life cycle.23,79 Beigel et al reported that remdesivir can significantly shorten the recovery time of COVID-19 patients with lower respiratory tract infections in a doubleblind, randomized controlled clinical study.80 Corticosteroids are important immunomodulators for the clinical treatment of SARS.81 Studies have shown that compared with patients with mild to moderate disease, patients with severe SARS-CoV-2 have higher levels of proinflammatory cytokines in serum samples.82 A meta-analysis indicated that the mortality ratewas reduced in severe COVID-19 patients treated with corticosteroids.83 More recently, the recovery collaborative group reported that dexamethasone (a type of corticosteroid) significantly decreased 28-day mortality in patients hospitalized with COVID-19.22 Corticosteroids have therefore become a potential treatment

for COVID-19 patients. Compared with remdesivir

or corticosteroids, MSC infusion has the potential to significantly reduce dyspnea in a relatively short period of time, as MSCs act by targeting secretory factors and MSCreleased extracellular vesicles deliver microRNA, mRNA, or DNA.84,85 The main methods currently employed to treat COVID-19 patients (especially severe and critically ill patients) include the following:

(1) convalescent plasma therapy;

(2) antiviral drug therapy;

(3) traditional Chinese and western medicine;

(4) MSC-based therapy;

(5)immune-mediated therapy.

Studies on these methods have accelerated the screening of effective drugs, explored new treatment methods, and attempted to prevent mild cases from progressing in severity.

目前，有效的疫苗是对抗SARS-CoV-2感染最好的方式，并且很多小组“有什么基础和与”已经提交了与疫苗发展相关初步措施和临床数据。然而，评估疫苗的安全性和有效性会需要相当长的时间周期。除了靶向疫苗的开发，为了结束全球流行这场与时间对抗的长跑中其他的治疗策略也在逐步发展。Remdesivir 是一种病毒 RNA依赖性抑制剂，靶向新生的病毒 RNA 链，导致病毒生命周期提前终止。Beigel等人报告说，在一项双盲、随机对照临床研究中Remdesivir可以显著缩短COVID-19下呼吸道感染康复时间。Corticosteroids 是一种很重要的免疫调节剂对于SARS的临床治疗。研究显示与“什么”轻度至中度疾病患者相比，重症SARS-CoV-2患者在“什么”血清样本中“有更高的什么”促炎细胞因子水平更高。一项meta分析表明在重症COVID-19患者“什么”接受皮质类固醇治疗中死亡率有所减少。近期，康复collaborative组报告了dexamethasone（一种皮质类固醇）显著降低COVID-19住院患者28天死亡率。因此Corticosteroids已成为新冠患者的潜在治疗方法。与remdesivir 或 corticosteroids相比，MSC注射在相对较短的时期内有一个显著减少呼吸困难，当MSC通过靶向“什么因素”分泌因子和MSC释放的细胞外囊泡传递microRNA, mRNA,or DNA的MSC起作用。对治疗新冠患者近期应用主要方法包括如下：

“什么”恢复期血浆治疗

抗病毒药物治疗

中西药结合

基于MSC治疗

免疫介导治疗

这些研究方法“什么”加速有效药物筛选，探索新的治疗方法和尝试在严重过程中阻止“什么的案例”轻症病情恶化。

（2021年6月30日星期三翻译654个词）

The current clinical study reports that MSC infusion enhanced the survival rate for severe or critically ill COVID-19 patients in both the FAS (92.31% survival in the experimental group vs 66.67% in the control group;P = .048) and the PPS (95.83% survival in the experimental group vs. 66.67% in the control group; P = .031).Our results agree with a previous report detailing the potential for MSC infusion to treat critically ill COVID-19 patients by alleviating acute respiratory dysfunction and pulmonary fibrosis.91 There are some other sources of MSCs used in clinical studies for treating COVID-19, and these are included in a systematic review and metaanalysis. Leng et al53 used UC-MSCs to treat seven COVID-19 patients, and had three control patients who were infected with COVID-19; there was 100% survival in the experimental group versus 66.67% survival in the control group. Shu et al95 investigated 12 severe COVID-19 patients using UC-MSCs as the experimental group, and 29 severe COVID-19 patients using a placebo as the control group. Their results showed a 100% 28-day survival rate in the experimental group versus 89.66% survival in the control group. More recently, Meng et al57 performed a study in 18 hospitalized patients with moderate to severe COVID-19 pulmonary disease, 9 of whom were treated with UCMSCinfusions andwith 9 control patients. All patients survived survived both in the experimental group and in the control group, but the degree of severity of COVID-19 (moderate to severe) might have affected the outcome. Leng et al,53 Shu et al,95 and our study enrolled more severe or critically ill COVID-19 patients. Recently, Sánchez-Guijo et al investigated 13 severe COVID-19 patients using an ADMSCs infusion for a clinical study that was nonrandomized and without a control; the results showed 84.62% survival using an AD-MSCs infusion. Therefore, MSC transplantation from different sources appears to be a candidate method to improve outcomes for critical cases. Coagulopathy and thromboprophylaxis are very common after MSC infusion.15 Current clinical data indicate that MSCs from human menstrual blood does not clot in patients, which is very favorable for intravenous infusions. One possible reason could be that MSCs express a low level of procoagulant tissue factor TF/CD142, which needs to be systematically investigated and verified in future preclinical studies.Although different sources of MSCs have been investigated for effectiveness in treating COVID-19, more optimized treatment strategies are critical to evaluate and control blood compatibility, optimize cell transfusion, and monitor the real-time dynamics of cells in the body to develop safer and more effective MSC treatments.43 Several concomitant treatments have been shown to exert a synergistic rolewith MSC transplantation. Of note, Peng et al reported that intravenous infusion of convalescent plasma as a treatment for severe COVID-19 may have synergistic characteristics with MSC transplantation in inhibiting cytokine storms,promoting lung injury repair, and recovery of pulmonary function. Although further study is required to establish safety and efficacy, the current body of evidence suggests that MSC transplantation might be an effective treatment for severe and critical COVID-19.

最近的临床研究表明MSC注射对重症和危重症COVID-19患者在FAS（试验组存活率92.31%VS对照组存活率66.67%；P=0.048）和PPS（试验组存活率95.83%VS对照组存活率66.67%；P=0.031）中都提升了存活率。我们的结果“同意一个什么的报告”和之前的一份报告一致，详细说明了MSC注射通过缓解急性呼吸阻碍和肺部纤维化来治疗危重症COVID-19患者潜力。这儿有一些其他来源的MSC用于治疗COVID-19临床研究，这些都包含在系统综述和荟萃分析中。

Leng等人使用UC-MSCs治疗了7例COVID-19患者，有3例感染COVID-19对照组患者，在试验组中有100%的存活率，相对来说在对照组中有66.67%存活。Shu等人调查了12例使用UC-MSCs的 COVID-19重症患者作为试验组，29例重症患者使用安慰剂的COVID-19重症患者作为对照组。他们的结果显示试验组28天内存活率是100%，相对来说对照组存活率是89.66%。近期，Meng等人实行了在18个住院患者缓解重症新冠肺部疾病，其中9个UC-MSC注射治疗，9个对照患者。在试验组和对照组中所有患者都存活了，但是COVID-19的严重程度可能会影响结局。Leng和Shu等人和我们的研究招募了更重症和危重症新冠患者。最近，Sánchez-Guijo等人调查了13例使用ADMSCs新冠患者进行了一场不随机无对照的临床试验。这个结果显示使用AD-MSCs注射的有84.62%存活率。因此，从不同来源的MSC移植显示是一种“什么样的”改善危重症案例结果候选方法。在MSC注射后， Coagulopathy 和thromboprophylaxis是非常普遍的。近期临床数据显示来自人类经血的MSC在患者中没有凝块，“它对于什么注射是非常好的”它非常有利于静脉注射。一个可能的原因可能是MSC表达“出什么因素”低水平促凝血因子TF/CD142，在未来临床研究上是需要更加系统调查和“多样化”验证。虽然MSCs不同来源治疗COVID-19有效性已经有研究，但更加优化的策略是非常重要的去评估和控制血液什么相容性，优化细胞输注，检测体内细胞的实时动态，发展更加安全和有效的MSC治疗。

许多合并治疗显示MSC移植发挥了协同作用角色。值得注意的是，Peng等人报道了，作为重症新冠治疗方法恢复期血浆静脉注射，与在抑制细胞因子风暴的MSC细胞移植促进肺损伤修复和肺功能修复上可能有协同作用特性。虽然研究要求进一步的建立安全性和有效性，目前证据表明MSC移植可能对重症和危重症COVID-19患者治疗有效。

In the current study, it was observed that many clinical symptoms were ameliorated in the 1-month period following MSC transplantation with combined therapy. No cases of pulmonary embolism were observed in the patients who underwent MSC infusion, although this side-effect is considered to be the main concern regarding MSC safety. Rather, our results indicate that MSC therapy is a safe and effective therapeutic strategy to rescue severe and critical lung problems induced by SARS-CoV-2. Thus, in the present study, preliminary clinical datawere provided with regard to the short-term safety (1-month follow-up) and therapeutic effect of MSC transplantation to treat severe and critically ill patients.

在本研究中，观察到在MSC移植和合并治疗一个月期间许多临床症状有所改善。“即使是重点关注MSC安全性作为单个影响，在经历MSC注射的患者中也没有观察到肺栓塞案例”，在接受MSC注射的患者中没有观察到肺栓塞病例，尽管这种副作用被认为是MSC安全性的主要问题。而且，我们的结果表明MSC治疗是安全有效的治疗策略对于减轻SARS-CoV-2感染的重症和危重症肺部问题。因此，在本研究中“什么”初步临床数据作为治疗重症和危重症患者短期安全性和MSC移植的治疗效果被提供。

The current study does not provide long-term evidence related to MSC-induced AEs. In a previous report from our group, MSCs were used to treat 17 H7N9 patients and four of those patients were followed up for 5 years without observing any AEs.55 In the current study of severe and critical COVID-19 patients, almost no significant differences in the occurrence of AEs in the short term were observed between the control group and the group receiving MSC transplantation. Hence, this study found that MSC infusion is associated with good safety outcomes. In addition,although the potential application value of MSC treatment in COVID-19 is obvious, the innate and adaptive immune compatibility test of MSC is incorporated into the current cell detection system, and the establishment of strict monitoring standards for biosafety and effectiveness with regard to the coagulopathy and thromboprophylaxis is crucial.15 Researchers should also pay strict attention to obtaining a suitable source, the product quality, monitoring of the various physiological and biochemical indicators of patients throughout the process, and strict prevention of unnecessary safety hazards.

本研究没有提供与MSC诱导AEs相关的长期证据。在我们组的一个前期报告，使用MSCs治疗的17例H7N9患者，其中4例被追踪5年没有被观察到AEs。在本研究中，重症和危重症新冠患者，在对照组和接受MSC移植组中短期观察的AEs发生率几乎没有显著性差异。因此，MSC注射和良好的安全性结局有关。另外，虽然在MSC治疗COVID-19的潜在应用价值是明显的，“MSC的什么和什么的免疫能力测试是什么进入细胞方向系统”MSC的先天和适应性免疫相容性测试是纳入现有细胞检测系统，并且在凝血功能障碍和血栓预防上生物安全性和有效性严格的早期标准建立是至关重要的。研究者应该更加严格的关注为了获取一个合适的来源，产生质量，监控患者多种生理和生化指标，并且严格阻止不需要的安全性隐患。

Recently, Leng et al53 published a clinical study on using MSCs to treat COVID-19 patients. This study investigated inflammatory and immune functioning as well as adverse effects in seven patients for 14 days post-MSC transplantation. The authors reported that MSCs appeared to significantly improve the functional outcomes of all seven patients without any observed AEs. However, more clinical data are still needed to identify any short-term adverse reactions following MSC administration. Zheng et al recently reported that 12 patients with moderate to severe ARDS did not experience any infusion-related reactions or serious treatment-related AEs following MSC transplantation. Additionally, Meng et al57 performed a study that included 18 hospitalized patients with moderate to severe COVID-19 pulmonary disease, nine of whom were treatedwithUC-MSC infusions. According to their results, intravenous UC-MSC infusion was safe and well-tolerated throughout the 1-month follow-up period. Although longterm follow-up data regarding the tolerability and safety of MSC transplantation are lacking, MSC transplantation may still be an effective method treatment for COVID-19, especially for severe and critical cases.

近期，leng等人发表了关于使用MSCs去治疗COVID-19患者临床研究。这个研究调查了7个患者MSCs移植14天后的炎症和免疫功能以及不良事件。这个作者报道了MSCs显示出显著提高功效结局

7例患者中没有观察到任何AE。然而，更多的临床数据需要去发现MSC管理中任何短期不良反应。Zheng等人近期报道12例中中度患者在MSC移植中没有经历任何注射相关反应或者严重治疗相关AEs。另外，Meng等人开展了一个研究，包括18例住院带有中重度COVID-19肺部感染患者，其中9例使用UC-MSC注射治疗。根据他们的结果，在整个1个月的随访期静脉注射是安全和良好的耐受性。虽然作为MSC移植的耐受和安全性长期随访数据是缺乏的，MSC移植对COVID-19特别是重症和危重症案例仍然是有效治疗方法。

There are several limitations to this exploratory trial. First and foremost, one patient experienced an AE over grade 3 associated with severe abnormal liver function. More data from a larger study are needed to determine whether MSC infusion can lead to an infusion reaction in certain patients, especially as infusion reactions can cause shortness of breath. Since only 26 patients were treated with MSCs in the current study and because we used a multicenter, open, and parallel-controlled study design, our study may not have detected important AEs associated with MSC treatment. Secondly, we should stress that this clinical trial did not use a standard design owing to the unique nature of the COVID-19 outbreak and the ethical limitations associated with treating severe COVID-19 patients. Thirdly, we reported that the experimental group showed greater improvements in CT results than the control group during the 1-month study period. However, we only observed significant improvements in expiratory dyspnea for the experimental group versus the control group on days 1, 3, and 5, and no differences were observed between the groups at other time points with regard to lung function. We speculate that MSCs exert a short-term effect to improve expiratory dyspnea, while the long-term improvements were more due to the actions of concomitant medications. Moreover, we did not observe significant changes in the levels of inflammatory factors following MSC infusion, even though mortality was significantly decreased in the experimental group. Therefore, the mechanism by whichMSCs reduce mortality should be investigated in future more comprehensive clinical trials. Moll et al investigated that the differences between fresh and cryopreserved MSCs were limited but significant.100 FreshMSCs are the best choices, however, considering the COVID-19 outbreak, the lack of sufficient donors for providing menstrual blood in a short time, and the consistent standard of care between the two hospitals situated in different cities, freshly thawed MSCs were used in this study. Finally, the small sample size of the current study limited our ability to obtain enough clinical data to draw strong conclusions.

这是探索性试验的一些限制。首先也是最重要的，一个患者经历了一次与严重非正常肺功能超过等级3的AE。需要来自更大研究更多的数据去确认MSC注射是否会导致在确定患者上的注射反应，尤其是作为注射反应会引起呼吸短促。由于在本研究中仅仅只有26个患者接受MSCs治疗，因为我们采用的是多中心、开放、和平行对照研究设计，我们的研究没有发生与MSC治疗相关的严重AEs。第二，我们需要强调这个临床研究没有使用标准设计，由于COVID-19爆发独特性质和与治疗重症COVID-19患者伦理限制（owing有归因于的意思）。第三，我们报告了在一个月研究期内试验组比对照组在CT结果上显示更大的改善。然而，我们仅仅只观察到试验组对于对照组在第1、3、5天呼气型呼吸困难有显著改善，根据肺部功能组之间在其他时间点上没有观察到差异。我们推测MSCs对于改善呼吸性呼吸苦难发挥了短期效果，然而长期效果更加取决于合并用药的反应。甚至，MSC注射后。在炎症因子水平上我们并没有观察到显著变化，即使在试验组死亡率有显著减少。因此，通过MSC减少死亡率这种机制在未来更多综合临床试验中应该被研究，新鲜的和冷冻保存的MSCs之间的差异是有限的但很重要。新鲜的MSCs是最好的选择，然而，考虑到COVID-19爆发，短期内提供经血足够捐献者缺乏，不同城市两个医院间一致标准的护理标准，本研究使用了新鲜解冻的MSCs。最后，本研究的小样本限制我们获取足够临床数据去挖掘更有力结论的能力。

5 CONCLUSIONS

This prospective and systematic study assessed the ability of menstrual blood-derived MSCs to treat both severe and critically ill COVID-19 patients. The results of this multicenter,open, and parallel-controlled clinical study suggest that menstrual blood-derived MSC transplantation significantly lowers the mortality of severe and critical SARSCoV-2-induced COVID-19. Menstrual blood-derivedMSCs may act by alleviating the breathing difficulties caused by COVID-19 and reducing the symptoms of ARDS or expiratory dyspnea. Although the body of research on MSCs is still in its infancy and lacks important long-term safety information, MSC-based therapymay serve in future clinical applications as an alternativemethod for the treatment of COVID-19.

5.结论

这个前言且系统的研究评估了经血来源MSCs治疗重症和危重症COVID-19患者的能力。这个多中心、开放、平行对照临床研究结果表明对于经血来源MSC移植治疗治疗重症和危重症COVID-19患者显著降低死亡率（lower是动词，降低）。经血来源MSCs可能起作用是通过缓解由COVID-19引起的呼吸困难和减少减轻ARDS或者呼吸性呼吸困难的症状。尽管在MSCs研究主题仍然它的初期在起步阶段且缺乏重要长期的安全性信息，在未来临床应用中MSC基础基于MSC治疗可能会作为一项治疗COVID-19有前景的替代方案（serve as作为什么服务于什么）。