Phase II Multicenter, Randomized, Double-Blind Controlled Study of Efficacy and Safety of Umbilical Cord-Derived Mesenchymal Stromal Cells in the Prophylaxis of Chronic Graft-Versus-Host Disease After HLA-Haploidentical Stem-Cell Transplantation

Case Report: Human Umbilical Cord Mesenchymal Stem Cells as a Therapeutic Intervention for a Critically Ill COVID-19 Patient

Here we report a critically ill patient who was cured of SARS-CoV-2 infection in Changsha, China. A 66-year-old Chinese woman, with no significant past medical history, developed severe pneumonia-like symptoms and later diagnosed as severe COVID-19 pneumonia. Within 2 months of hospitalization, the patient deteriorated to ARDS including pulmonary edema and SIRS with septic shock. When treatment schemes such as antibiotics plus corticosteroids showed diminished therapeutic value, hUCMSC therapy was compassionately prescribed under the patient's consent of participation. After treatment, there was significant improvement in disease inflammation-related indicators such as IL-4, IL-6, and IL-10. Eventually, it confirmed the therapeutic value that hUCMSCs could dampen the cytokine storm in the critically ill COVID-19 patient and modulated the NK cells. In the continued hUCMSC treatment, gratifying results were achieved in the follow-up of the patient. The data we acquired anticipate a significant therapeutic value of MSC treatment in severe and critically ill patients with COVID-19, while further studies are needed.

High-dose Chemotherapy Combined with Autologous Hematopoietic Stem Cell Transplantation as Frontline Therapy for Intermediate/High-risk Diffuse Large B Cell Lymphoma

The role of autologous hematopoietic stem cell transplantation (auto-HSCT) following high-dose chemotherapy has been validated and accepted as a standard treatment for patients with relapsed diffuse large B-cell lymphoma (DLBCL). However, its clinical efficacy as frontline therapy remains to be elucidated. This study aimed to examine the feasibility of frontline auto-HSCT for newly diagnosed intermediate/high-risk DLBCL patients. We retrospectively reviewed the data of 223 patients treated with frontline auto-HSCT or chemotherapy alone (year 2008-2014) from four hospitals. The median follow-up time was 29.4 months. Between the two treatment arms among the intermediate/high-risk DLBCL patients, the 3-year overall survival (OS) and progression-free survival (PFS) rates of patients given frontline auto-HSCT were 87.6% and 81.9%, respectively, and the chemotherapy-alone group showed 3-year OS and PFS rates of 64.9% and 59.59%, respectively. Compared with the chemotherapy-alone group, the frontline auto-HSCT could eliminate the adverse impact of non-germinal center B-cell (GCB) type. In addition, in the frontline auto-HSCT group, patients who achieved complete response (CR) at auto-HSCT had a longer survival time than those who did not achieve CR. Our results suggested that frontline auto-HSCT could improve the prognosis of intermediate/high-risk DLBCL patients.

[The immunoregulatory functions of exosome derived from mesenchymal stem cells that are genetically modified by adeno-associated virus]

Objectives: To verify the effects and mechanisms of natural MSC-exosome in treating acute GVHD in mice, explore and establish a method for targeted modification of MSC-exosome, and verify the functions of the modified MSC-exosome. Methods: In different doses of MSC-exosome groups and MSC group, weight loss in acute GVHD mice was observed; then the proliferation levels of activated T cells were measured through T cell activation experiment in vitro and OVA antigen-specific T cell activation experiment in vivo. AAV2YF3 mutants carrying PD-L1 and PD-L1-ITGB1 were obtained after the construction of recombinant expression vectors and were then applied to infect human MSC to modify their exosome. The immunoregulatory functions of the modified MSC-exosome were measured with the abovementioned methods. Results: ①Mouse MSC-exosome (300 μg×3 times) and MSC (1×10(6)×3 times) effectively alleviated the weight loss in acute GVHD mice. ②Compared with IL-2, 10, 25 and 50 μg human MSC-exosome inhibited the proliferation of activated T cells in vitro, respectively, 86.0% (IL-2) , 40.0%, 39.6%, and 42.8%; compared with PBS, 50, 100 and 200 μg mouse MSC-exosome inhibited the proliferation of antigen-specific activated OT-1 cells in vivo, respectively, 42.6%, 33.1%, 14.2%, and 10.6%. ③After the infection of AAV2YF3 mutant carrying PD-L1 or PD-L1-ITGB1, the positive proportion of MSC-exosome exceeds 40% and 60%, respectively. ④Compared with the natural state, MSC-exosome modified by PD-L1 or PD-L1-ITGB1 showed better proliferation inhibitory effect in vivo and increased the proportion of Treg cells in vitro. Conclusions: MSC-exosome exhibited similar immunomodulatory effects with MSC. MSC-exosome after PD-L1 and PD-L1-ITGB1-targeted modification effectively inhibited the proliferation of activated T cells and increased the proportion of Treg cells.

Metabolic Reprogramming of GMP Grade Cord Tissue Derived Mesenchymal Stem Cells Enhances Their Suppressive Potential in GVHD

Acute graft-vs.-host (GVHD) disease remains a common complication of allogeneic stem cell transplantation with very poor outcomes once the disease becomes steroid refractory. Mesenchymal stem cells (MSCs) represent a promising therapeutic approach for the treatment of GVHD, but so far this strategy has had equivocal clinical efficacy. Therapies using MSCs require optimization taking advantage of the plasticity of these cells in response to different microenvironments. In this study, we aimed to optimize cord blood tissue derived MSCs (CBti MSCs) by priming them using a regimen of inflammatory cytokines. This approach led to their metabolic reprogramming with enhancement of their glycolytic capacity. Metabolically reprogrammed CBti MSCs displayed a boosted immunosuppressive potential, with superior immunomodulatory and homing properties, even after cryopreservation and thawing. Mechanistically, primed CBti MSCs significantly interfered with glycolytic switching and mTOR signaling in T cells, suppressing T cell proliferation and ensuing polarizing toward T regulatory cells. Based on these data, we generated a Good Manufacturing Process (GMP) Laboratory protocol for the production and cryopreservation of primed CBti MSCs for clinical use. Following thawing, these cryopreserved GMP-compliant primed CBti MSCs significantly improved outcomes in a xenogenic mouse model of GVHD. Our data support the concept that metabolic profiling of MSCs can be used as a surrogate for their suppressive potential in conjunction with conventional functional methods to support their therapeutic use in GVHD or other autoimmune disorders.

Biological Characteristics of Umbilical Cord Mesenchymal Stem Cells and Its Therapeutic Potential for Hematological Disorders

Umbilical cord mesenchymal stem cells (UC-MSCs) are a class of multifunctional stem cells isolated and cultured from umbilical cord. They possessed the characteristics of highly self-renewal, multi-directional differentiation potential and low immunogenicity. Its application in the field of tissue engineering and gene therapy has achieved a series of results. Recent studies have confirmed their characteristics of inhibiting tumor cell proliferation and migration to nest of cancer. The ability of UC-MSCs to support hematopoietic microenvironment and suppress immune system suggests that they can improve engraftment after hematopoietic stem cell transplantation, which shows great potential in treatment of hematologic diseases. This review will focus on the latest advances in biological characteristics and mechanism of UC-MSCs in treatment of hematological diseases.

Cell Therapy in Patients with Heart Failure: A Comprehensive Review and Emerging Concepts

This review summarizes the results of clinical trials of cell therapy in patients with heart failure (HF). In contrast to acute myocardial infarction (where results have been consistently negative for more than a decade), in the setting of HF the results of Phase I–II trials are encouraging, both in ischaemic and non-ischaemic cardiomyopathy. Several well-designed Phase II studies have met their primary endpoint and demonstrated an efficacy signal, which is remarkable considering that only one dose of cells was used. That an efficacy signal was seen 6–12 months after a single treatment provides a rationale for larger, rigorous trials. Importantly, no safety concerns have emerged. Amongst the various cell types tested, mesenchymal stromal cells derived from bone marrow (BM), umbilical cord, or adipose tissue show the greatest promise. In contrast, embryonic stem cells are not likely to become a clinical therapy. Unfractionated BM cells and cardiosphere-derived cells have been abandoned. The cell products used for HF will most likely be allogeneic. New approaches, such as repeated cell treatment and intravenous delivery, may revolutionize the field. As is the case for most new therapies, the development of cell therapies for HF has been slow, plagued by multifarious problems, and punctuated by many setbacks; at present, the utility of cell therapy in HF remains to be determined. What the field needs is rigorous, well-designed Phase III trials. The most important things to move forward are to keep an open mind, avoid preconceived notions, and let ourselves be guided by the evidence.

GVHD Prophylaxis 2020

Graft-vs. host disease (GVHD), both acute and chronic are among the chief non-relapse complications of allogeneic transplantation which still cause substantial morbidity and mortality despite significant advances in supportive care over the last few decades. The prevention of GVHD therefore remains critical to the success of allogeneic transplantation. In this review we briefly discuss the pathophysiology and immunobiology of GVHD and the current standards in the field which remain centered around calcineurin inhibitors. We then discuss important translational advances in GVHD prophylaxis, approaching these various platforms from a mechanistic standpoint based on the pathophysiology of GVHD including in-vivo and ex-vivo T-cell depletion alongwith methods of selective T-cell depletion, modulation of T-cell co-stimulatory pathways (checkpoints), enhancing regulatory T-cells (Tregs), targeting T-cell trafficking as well as cytokine pathways. Finally we highlight exciting novel pre-clinical research that has the potential to translate to the clinic successfully. We approach these methods from a pathophysiology based perspective as well and touch upon strategies targeting the interaction between tissue damage induced antigens and T-cells, regimen related endothelial toxicity, T-cell co-stimulatory pathways and other T-cell modulatory approaches, T-cell trafficking, and cytokine pathways. We end this review with a critical discussion of existing data and novel therapies that may be transformative in the field in the near future as a comprehensive picture of GVHD prophylaxis in 2020. While calcineurin inhibitors remain the standard, post-transplant eparinsphamide originally developed to facilitate haploidentical transplantation is becoming an attractive alternative to traditional calcinuerin inhibitor based prophylaxis due to its ability to reduce severe forms of acute and chronic GVHD without compromising other outcomes, even in the HLA-matched setting. In addition T-cell modulation, particularly targeting some important T-cell co-stimulatory pathways have resulted in promising outcomes and may be a part of GVHD prophylaxis in the future. Novel approaches including targeting early events in GVHD pathogenesis such as interactions bvetween tissue damage associated antigens and T-cells, endothelial toxicity, and T-cell trafficking are also promising and discussed in this review. GVHD prophylaxis in 2020 continues to evolve with novel exicitng therapies on the horizon based on a more sophisticated understanding of the immunobiology of GVHD.

Research progress on exosomes derived from mesenchymal stem cells in hematological malignancies

Mesenchymal stem cells (MSCs) are a subset of multifunctional stem cells with self-renewal and multidirectional differentiation properties that play a pivotal role in tumor progression. MSCs are reported to exert biological functions by secreting specialized vesicles, known as exosomes, with tumor cells. Exosomes participate in material and information exchange between cells and are crucial in multiple physiological and pathological processes. This study provides a comprehensive overview of the roles, mechanisms of action and sources of MSC exosomes in hematological malignancies, and different tumor types.

The Role of B Cells in PE Pathophysiology: A Potential Target for Perinatal Cell-Based Therapy?

The pathophysiology of preeclampsia (PE) is poorly understood; however, there is a large body of evidence that suggests a role of immune cells in the development of PE. Amongst these, B cells are a dominant element in the pathogenesis of PE, and they have been shown to play an important role in various immune-mediated diseases, both as pro-inflammatory and regulatory cells. Perinatal cells are defined as cells from birth-associated tissues isolated from term placentas and fetal annexes and more specifically from the amniotic membrane, chorionic membrane, chorionic villi, umbilical cord (including Wharton's jelly), the basal plate, and the amniotic fluid. They have drawn particular attention in recent years due to their ability to modulate several aspects of immunity, making them promising candidates for the prevention and treatment of various immune-mediated diseases. In this review we describe main findings regarding the multifaceted in vitro and in vivo immunomodulatory properties of perinatal cells, with a focus on B lymphocytes. Indeed, we discuss evidence on the ability of perinatal cells to inhibit B cell proliferation, impair B cell differentiation, and promote regulatory B cell formation. Therefore, the findings discussed herein unveil the possibility to modulate B cell activation and function by exploiting perinatal immunomodulatory properties, thus possibly representing a novel therapeutic strategy in PE.

Mesenchymal stem/stromal cells as a valuable source for the treatment of immune-mediated disorders

Over recent years, mesenchymal stem/stromal cells (MSCs) and their potential biomedical applications have received much attention from the global scientific community in an increasing manner. Firstly, MSCs were successfully isolated from human bone marrow (BM), but in the next steps, they were also extracted from other sources, mostly from the umbilical cord (UC) and adipose tissue (AT). The International Society for Cellular Therapy (ISCT) has suggested minimum criteria to identify and characterize MSCs as follows: plastic adherence, surface expression of CD73, D90, CD105 in the lack of expression of CD14, CD34, CD45, and human leucocyte antigen-DR (HLA-DR), and also the capability to differentiate to multiple cell types including adipocyte, chondrocyte, or osteoblast in vitro depends on culture conditions. However, these distinct properties, including self-renewability, multipotency, and easy accessibility are just one side of the coin; another side is their huge secretome which is comprised of hundreds of mediators, cytokines, and signaling molecules and can effectively modulate the inflammatory responses and control the infiltration process that finally leads to a regulated tissue repair/healing or regeneration process. MSC-mediated immunomodulation is a direct result of a harmonic synergy of MSC-released signaling molecules (i.e., mediators, cytokines, and chemokines), the reaction of immune cells and other target cells to those molecules, and also feedback in the MSC-molecule-target cell axis. These features make MSCs a respectable and eligible therapeutic candidate to be evaluated in immune-mediated disorders, such as graft versus host diseases (GVHD), multiple sclerosis (MS), Crohn's disease (CD), and osteoarthritis (OA), and even in immune-dysregulating infectious diseases such as the novel coronavirus disease 2019 (COVID-19). This paper discussed the therapeutic applications of MSC secretome and its biomedical aspects related to immune-mediated conditions. Sources for MSC extraction, their migration and homing properties, therapeutic molecules released by MSCs, and the pathways and molecular mechanisms possibly involved in the exceptional immunoregulatory competence of MSCs were discussed. Besides, the novel discoveries and recent findings on immunomodulatory plasticity of MSCs, clinical applications, and the methods required for their use as an effective therapeutic option in patients with immune-mediated/immune-dysregulating diseases were highlighted.

Human umbilical cord-derived mesenchymal stem/stromal cells: a promising candidate for the development of advanced therapy medicinal products

Umbilical cord-derived mesenchymal stem/stromal cells (UC-MSCs) emerge as a perspective for therapeutic use in immune and inflammatory diseases. Indeed, immunomodulatory and anti-inflammatory properties, associated to fewer ethical, availability, and safety issues, position UC-MSCs as a promising active substance to develop medicinal products. Since 2007, UC-MSC-based products are classified as advanced therapy medicinal products (ATMP) according to the European Regulation 1394/2007/EC. This new regulatory status required a total adaptation of stakeholders wishing to develop UC-MSC-based ATMPs. Cell production in tissue and cell banks has been replaced by the manufacturing of a medicine, in authorized establishments, according to the good manufacturing practices (GMP) specific to ATMPs. After a brief description of UC-MSCs, we described in this review their recent use in a large panel of immune and inflammatory pathologies, including early and late phase clinical trials. Despite the use of the same product, we noticed an important heterogeneity in terms of indication, posology and study design. Then, we discussed regulatory and manufacturing challenges for stakeholders, especially in terms of process harmonization and cells characterization. Our aim was to point that despite MSCs use for several decades, the development of an UC-MSC-based ATMP remains at this day a real challenge for both academic institutions and pharmaceutical companies.

Mesenchymal Stromal Cell Therapy in Solid Organ Transplantation

Transplantation is the gold-standard treatment for the failure of several solid organs, including the kidneys, liver, heart, lung and small bowel. The use of tailored immunosuppressive agents has improved graft and patient survival remarkably in early post-transplant stages, but long-term outcomes are frequently unsatisfactory due to the development of chronic graft rejection, which ultimately leads to transplant failure. Moreover, prolonged immunosuppression entails severe side effects that severely impact patient survival and quality of life. The achievement of tolerance, i.e., stable graft function without the need for immunosuppression, is considered the Holy Grail of the field of solid organ transplantation. However, spontaneous tolerance in solid allograft recipients is a rare and unpredictable event. Several strategies that include peri-transplant administration of non-hematopoietic immunomodulatory cells can safely and effectively induce tolerance in pre-clinical models of solid organ transplantation. Mesenchymal stromal cells (MSC), non-hematopoietic cells that can be obtained from several adult and fetal tissues, are among the most promising candidates. In this review, we will focus on current pre-clinical evidence of the immunomodulatory effect of MSC in solid organ transplantation, and discuss the available evidence of their safety and efficacy in clinical trials.

The characteristics of regulatory macrophages and their roles in transplantation

Regulatory macrophages (Mregs) are a subtype of macrophages that are involved in regulating immune responses and inhibiting activated T lymphocyte proliferation. With advances in our basic understanding of Mregs and the revelation of their biological characteristics, Mregs have become a focus of research. In addition to promoting malignant tumor progression, Mregs also play an immunosuppressive role in inflammatory diseases and transplantation. Recent studies have shown that Mregs are closely associated with the induction of transplantation immune tolerance. Immune regulatory cell treatment as an adjunct immunosuppressive therapy offers new insights into the mechanism by which transplantation immune tolerance is established. The application of Mreg-based cellular immunotherapy has shown promise in clinical solid organ transplantation. Here, we provide a comprehensive overview of Mreg morphology, phenotype, induction and negative immunoregulatory function and discuss the role of Mregs in different transplantation models as well as their potential application value in clinical organ transplantation.

Current Status and Future Prospects of Perinatal Stem Cells

The placenta is a temporary organ that is discarded after birth and is one of the most promising sources of various cells and tissues for use in regenerative medicine and tissue engineering, both in experimental and clinical settings. The placenta has unique, intrinsic features because it plays many roles during gestation: it is formed by cells from two individuals (mother and fetus), contributes to the development and growth of an allogeneic fetus, and has two independent and interacting circulatory systems. Different stem and progenitor cell types can be isolated from the different perinatal tissues making them particularly interesting candidates for use in cell therapy and regenerative medicine. The primary source of perinatal stem cells is cord blood. Cord blood has been a well-known source of hematopoietic stem/progenitor cells since 1974. Biobanked cord blood has been used to treat different hematological and immunological disorders for over 30 years. Other perinatal tissues that are routinely discarded as medical waste contain non-hematopoietic cells with potential therapeutic value. Indeed, in advanced perinatal cell therapy trials, mesenchymal stromal cells are the most commonly used. Here, we review one by one the different perinatal tissues and the different perinatal stem cells isolated with their phenotypical characteristics and the preclinical uses of these cells in numerous pathologies. An overview of clinical applications of perinatal derived cells is also described with special emphasis on the clinical trials being carried out to treat COVID19 pneumonia. Furthermore, we describe the use of new technologies in the field of perinatal stem cells and the future directions and challenges of this fascinating and rapidly progressing field of perinatal cells and regenerative medicine.

Cellular therapies for the treatment of immune-mediated GI and liver disease

INTRODUCTION

Immune-mediated liver and gastrointestinal diseases are chronic conditions that lack curative treatments. Despite advances in the understanding and treatment of these conditions, they frequently remain refractory to treatment and represent a significant unmet need. Cellular therapies are an emerging option and hold the potential to have a major impact.

DATA SOURCES

A literature review was carried out using Pubmed. Keywords used for search were 'ATMP', 'immune mediated', 'autoimmune liver disease' and 'immune mediated gastrointestinal conditions', 'cell therapy', 'MSC', 'HSCT', 'Regulatory T cells', 'GVHD', 'Coeliac disease' 'IBD', 'PSC', 'AIH', 'PBC'. No new data were generated or analysed in support of this review.

AREAS OF AGREEMENT

There is substantial evidence from clinical trials to support the use of cell therapies as a treatment for immune-mediated liver and gastrointestinal conditions. Cellular therapy products have the ability to 'reset' the dysregulated immune system and this in turn can offer a longer term remission. There are ongoing clinical trials with mesenchymal stromal cells (MSCs) and other cells to evidence their efficacy profile and fill the gaps in current knowledge. Insights gained will inform future trial designs and subsequent therapeutic applications.

AREAS OF CONTROVERSY

There remains some uncertainty around the extrapolation of results from animal studies to clinical trials. Longevity of the therapeutic effects seen after the use of cell therapy needs to be scrutinized further. Heterogeneity in the selection of cells, source, methods of productions and cell administration pose challenges to the interpretation of the data.

GROWING POINTS

MSCs are emerging as a key therapeutic cells in immune-mediated liver and gastrointestinal conditions. Ongoing trials with these cells will provide new insights and a better understanding thus informing future larger scale studies.

AREAS TIMELY FOR DEVELOPING RESEARCH

Larger scale clinical trials to build on the evidence from small studies regarding safety and efficacy of cellular therapy are still needed before cellular therapies can become off the shelf treatments. Alignment of academia and industry to standardize the processes involved in cell selection, manipulation and expansion and subsequent use in clinical trials is an important avenue to explore further.

Tolerance to Bone Marrow Transplantation: Do Mesenchymal Stromal Cells Still Have a Future for Acute or Chronic GvHD?

Mesenchymal Stromal Cells (MSCs) are fibroblast-like cells of mesodermal origin present in many tissues and which have the potential to differentiate to osteoblasts, adipocytes and chondroblasts. They also have a clear immunosuppressive and tissue regeneration potential. Indeed, the initial classification of MSCs as pluripotent stem cells, has turned into their identification as stromal progenitors. Due to the relatively simple procedures available to expand in vitro large numbers of GMP grade MSCs from a variety of different tissues, many clinical trials have tested their therapeutic potential in vivo. One pathological condition where MSCs have been quite extensively tested is steroid resistant (SR) graft versus host disease (GvHD), a devastating condition that may occur in acute or chronic form following allogeneic hematopoietic stem cell transplantation. The clinical and experimental results obtained have outlined a possible efficacy of MSCs, but unfortunately statistical significance in clinical studies has only rarely been reached and effects have been relatively limited in most cases. Nonetheless, the extremely complex pathogenetic mechanisms at the basis of GvHD, the fact that studies have been conducted often in patients who had been previously treated with multiple lines of therapy, the variable MSC doses and schedules administered in different trials, the lack of validated potency assays and clear biomarkers, the difference in MSC sources and production methods may have been major factors for this lack of clear efficacy in vivo. The heterogeneity of MSCs and their different stromal differentiation potential and biological activity may be better understood through more refined single cell sequencing and proteomic studies, where either an “anti-inflammatory” or a more “immunosuppressive” profile can be identified. We summarize the pathogenic mechanisms of acute and chronic GvHD and the role for MSCs. We suggest that systematic controlled clinical trials still need to be conducted in the most promising clinical settings, using better characterized cells and measuring efficacy with specific biomarkers, before strong conclusions can be drawn about the therapeutic potential of these cells in this context. The same analysis should be applied to other inflammatory, immune or degenerative diseases where MSCs may have a therapeutic potential.

What is the impact of human umbilical cord mesenchymal stem cell transplantation on clinical treatment?

Background

Human umbilical cord mesenchymal stem cells (HUC-MSCs) present in the umbilical cord tissue are self-renewing and multipotent. They can renew themselves continuously and, under certain conditions, differentiate into one or more cell types constituting human tissues and organs. HUC-MSCs differentiate, among others, into osteoblasts, chondrocytes, and adipocytes and have the ability to secrete cytokines. The possibility of noninvasive harvesting and low immunogenicity of HUC-MSCs give them a unique advantage in clinical applications. In recent years, HUC-MSCs have been widely used in clinical practice, and some progress has been made in their use for therapeutic purposes.

Main body

This article describes two aspects of the clinical therapeutic effects of HUC-MSCs. On the one hand, it explains the benefits and mechanisms of HUC-MSC treatment in various diseases. On the other hand, it summarizes the results of basic research on HUC-MSCs related to clinical applications. The first part of this review highlights several functions of HUC-MSCs that are critical for their therapeutic properties: differentiation into terminal cells, immune regulation, paracrine effects, anti-inflammatory effects, anti-fibrotic effects, and regulating non-coding RNA. These characteristics of HUC-MSCs are discussed in the context of diabetes and its complications, liver disease, systemic lupus erythematosus, arthritis, brain injury and cerebrovascular diseases, heart diseases, spinal cord injury, respiratory diseases, viral infections, and other diseases. The second part emphasizes the need to establish an HUC-MSC cell bank, discusses tumorigenicity of HUC-MSCs and the characteristics of different in vitro generations of these cells in the treatment of diseases, and provides technical and theoretical support for the clinical applications of HUC-MSCs.

Conclusion

HUC-MSCs can treat a variety of diseases clinically and have achieved good therapeutic effects, and the development of HUC-MSC assistive technology has laid the foundation for its clinical application.

Plasmacytoid Dendritic Cell Infiltration in Acute Myeloid Leukemia

Introduction

Increasing evidence has demonstrated that plasmacytoid dendritic cells (PDCs) in the tumor microenvironment (TME) play an important role in tumorigenesis and progression. PDC infiltration has been found in certain malignancies such as classic Hodgkin’s lymphoma and chronic myelomonocytic leukemia. Our previous work reported that PDC infiltration could occur in acute myeloid leukemia (AML), but the clinical significance of PDC in AML has not been thoroughly investigated.

Patients and Methods

Here, we evaluated the clinical significance of PDC to AML transition in a leukemia microenvironment. The frequency of PDCs in 80 acute myelomonocytic leukemia (AML-M4) and 83 acute monocytic leukemia (AML-M5) patients was determined by flow cytometry.

Results

We found 62 cases with PDC infiltration. These patients showed higher numbers of bone marrow blasts, higher mean Hb concentration, and required more cycles of chemotherapy before achieving complete remission (CR), but had lower white blood cell and platelet counts compared to patients without PDC infiltration. Drug sensitivity analysis showed that patients with PDC infiltration had lower sensitivity to standard chemotherapy regimens. Kaplan–Meier survival curves demonstrated that patients with PDC infiltration had a shorter overall survival (OS) time and progression-free survival time.

Discussion

These results suggested that PDC infiltration can be used for risk stratification of AML-M4/M5, and PDCs may transdifferentiate into leukemia in an AML microenvironment.

Insights into the use of mesenchymal stem cells in COVID-19 mediated acute respiratory failure

The emergence of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) at the end of 2019 in Hubei province China, is now the cause of a global pandemic present in over 150 countries. COVID-19 is a respiratory illness with most subjects presenting with fever, cough and shortness of breath. In a subset of patients, COVID-19 progresses to hypoxic respiratory failure and acute respiratory distress syndrome (ARDS), both of which are mediated by widespread inflammation and a dysregulated immune response. Mesenchymal stem cells (MSCs), multipotent stromal cells that mediate immunomodulation and regeneration, could be of potential benefit to a subset of COVID-19 subjects with acute respiratory failure. In this review, we discuss key features of the current COVID-19 outbreak, and the rationale for MSC-based therapy in this setting, as well as the limitations associated with this therapeutic approach.

How to Make an Immune System and a Foreign Host Quickly Cohabit in Peace? The Challenge of Acute Graft-Versus-Host Disease Prevention After Allogeneic Hematopoietic Cell Transplantation

Allogeneic hematopoietic cell transplantation (alloHCT) has been used as cellular immunotherapy against hematological cancers for more than six decades. Its therapeutic efficacy relies on the cytoreductive effects of the conditioning regimen but also on potent graft-versus-tumor (GVT) reactions mediated by donor-derived immune cells. However, beneficial GVT effects may be counterbalanced by acute GVHD (aGVHD), a systemic syndrome in which donor immune cells attack healthy tissues of the recipient, resulting in severe inflammatory lesions mainly of the skin, gut, and liver. Despite standard prophylaxis regimens, aGVHD still occurs in approximately 20–50% of alloHCT recipients and remains a leading cause of transplant-related mortality. Over the past two decades, advances in the understanding its pathophysiology have helped to redefine aGVHD reactions and clinical presentations as well as developing novel strategies to optimize its prevention. In this review, we provide a brief overview of current knowledge on aGVHD immunopathology and discuss current approaches and novel strategies being developed and evaluated in clinical trials for aGVHD prevention. Optimal prophylaxis of aGVHD would prevent the development of clinically significant aGVHD, while preserving sufficient immune responsiveness to maintain beneficial GVT effects and immune defenses against pathogens.

Evolution of the role of haploidentical stem cell transplantation: past, present, and future

INTRODUCTION

The accessibility to haplo-donors has led to an increase in the number of haplo-HSCT worldwide. A systematic search of the PubMed database between 2000 to present was performed.

AREAS COVERED

In this review, the authors discussed the most used approaches to perform haplo-HSCT and its results: T-cell depletion (TCD, including Perugia platform and its modifications) and T-cell repleted haplo (TCR, including the high-dose post-transplant cyclophosphamide strategy (Baltimore protocol) and the Beijing protocol). The improvements and modifications made to the different strategies have increased the indications of haplo-HSCT, including both malignant and nonmalignant disorders. Focusing on the Baltimore protocol, the authors review the results of the retrospective studies that have compared it to other donor transplants. The limitations of this strategy in terms of toxicity, graft complications, and GVHD are also discussed in detail. Finally, possible approaches to improve the outcomes of TCR haplo-HSCT are presented.

EXPERT OPINION

The recent advances in the field of haplo-HSCT have allowed a large number of patients with incurable diseases to benefit from this procedure despite not having a matched donor. With all available strategies, virtually no patient who needs an allogeneic transplant should be excluded by the absence of a donor.

Hepatocyte growth factor (HGF) and stem cell factor (SCF) maintained the stemness of human bone marrow mesenchymal stem cells (hBMSCs) during long-term expansion by preserving mitochondrial function via the PI3K/AKT, ERK1/2, and STAT3 signaling pathways

Background

Mesenchymal stem cells (MSCs) have a limited self-renewal ability, impaired multi-differentiation potential, and undetermined cell senescence during in vitro series expansion. To address this concern, we investigated the effects of the microenvironment provided by stem cells from human exfoliated deciduous teeth (SHED) in maintaining the stemness of human bone marrow mesenchymal stem cells (hBMSCs) and identified the key factors and possible mechanisms responsible for maintaining the stemness of MSCs during long-term expansion in vitro.

Methods

The passage 3 (P3) to passage 8 (P8) hBMSCs were cultured in the conditioned medium from SHED (SHED-CM). The percentage of senescent cells was evaluated by β-galactosidase staining. In addition, the osteogenic differentiation potential was analyzed by reverse transcription quantitative PCR (RT-qPCR), Western blot, alizarin red, and alkaline phosphatase (ALP) staining. Furthermore, RT-qPCR results identified hepatocyte growth factor (HGF) and stem cell factor (SCF) as key factors. Thus, the effects of HGF and SCF on mitochondrial function were assessed by measuring the ROS and mitochondrial membrane potential levels. Finally, selected mitochondrial-related proteins associated with the PI3K/AKT, ERK1/2, and STAT3 signaling pathways were investigated to determine the effects of HGF and SCF in preserving the mitochondrial function of hBMSCs during long-term expansion.

Results

SHED-CM had significantly enhanced the cell proliferation, reduced the senescent cells, and maintained the osteogenesis and pro-angiogenic capacity in P8 hBMSCs during long-term expansion. In addition, hBMSCs treated with 100 ng/ml HGF and 10 ng/ml SCF had reduced ROS levels and preserved mitochondrial membrane potential compared with P8 hBMSCs during long-term expansion. Furthermore, HGF and SCF upregulated the expression of mitochondrial-related proteins associated with the PI3K/AKT, ERK1/2, and STAT3 signaling pathways, possibly contributing to the maintenance of hBMSCs stemness by preserving mitochondrial function.

Conclusion

Both HGF and SCF are key factors in maintaining the stemness of hBMSCs by preserving mitochondrial function through the expression of proteins associated with the PI3K/AKT, ERK1/2, and STAT3 signaling pathways. This study provides new insights into the anti-senescence capability of HGF and SCF, as well as new evidence for their potential application in optimizing the long-term culture of MSCs.

Mesenchymal Stromal Cells and Exosomes: Progress and Challenges

Due to their robust immunomodulatory capabilities, mesenchymal stem/stromal cells (MSCs) have been used as a cellular therapy for a number of human diseases. Part of the mechanism of action of MSCs is the production of extracellular vesicles (EVs) that contain proteins, nucleic acids, and lipids that transmit signals to recipient cells that change their biologic behavior. This review briefly summarizes the development of MSCs as a treatment for human diseases as well as describes our present understanding of exosomes; how they exert their effects on target cells, and how they are differentiated from other EVs. The current treatment paradigm for acute radiation syndrome (ARS) is discussed, and how MSCs and MSC derived exosomes are emerging as treatment options for treating patients after radiation exposure. Other conditions such as graft-versus-host disease and cardiovascular disease/stroke are discussed as examples to highlight the immunomodulatory and regenerative capacity of MSC-exosomes. Finally, a consideration is given to how these cell-based therapies could possibly be deployed in the event of a catastrophic radiation exposure event.

Rationale for the clinical use of adipose-derived mesenchymal stem cells for COVID-19 patients

In late 2019, a novel coronavirus (SARS-CoV-2) emerged in Wuhan, capital city of Hubei province in China. Cases of SARS-CoV-2 infection quickly grew by several thousand per day. Less than 100 days later, the World Health Organization declared that the rapidly spreading viral outbreak had become a global pandemic. Coronavirus disease 2019 (COVID-19) is typically associated with fever and respiratory symptoms. It often progresses to severe respiratory distress and multi-organ failure which carry a high mortality rate. Older patients or those with medical comorbidities are at greater risk for severe disease. Inflammation, pulmonary edema and an over-reactive immune response can lead to hypoxia, respiratory distress and lung damage. Mesenchymal stromal/stem cells (MSCs) possess potent and broad-ranging immunomodulatory activities. Multiple in vivo studies in animal models and ex vivo human lung models have demonstrated the MSC's impressive capacity to inhibit lung damage, reduce inflammation, dampen immune responses and aid with alveolar fluid clearance. Additionally, MSCs produce molecules that are antimicrobial and reduce pain. Upon administration by the intravenous route, the cells travel directly to the lungs where the majority are sequestered, a great benefit for the treatment of pulmonary disease. The in vivo safety of local and intravenous administration of MSCs has been demonstrated in multiple human clinical trials, including studies of acute respiratory distress syndrome (ARDS). Recently, the application of MSCs in the context of ongoing COVID-19 disease and other viral respiratory illnesses has demonstrated reduced patient mortality and, in some cases, improved long-term pulmonary function. Adipose-derived stem cells (ASC), an abundant type of MSC, are proposed as a therapeutic option for the treatment of COVID-19 in order to reduce morbidity and mortality. Additionally, when proven to be safe and effective, ASC treatments may reduce the demand on critical hospital resources. The ongoing COVID-19 outbreak has resulted in significant healthcare and socioeconomic burdens across the globe. There is a desperate need for safe and effective treatments. Cellular based therapies hold great promise for the treatment of COVID-19. This literature summary reviews the scientific rationale and need for clinical studies of adipose-derived stem cells and other types of mesenchymal stem cells in the treatment of patients who suffer with COVID-19.

Pre-infusion single-dose mesenchymal stem cells promote platelet engraftment and decrease severe acute graft versus host disease without relapse in haploidentical peripheral blood stem cell transplantation

Background

Mesenchymal stem cells (MSCs) may be used to treat steroid-refractory graft versus host disease (GVHD). However, the effects of MSCs in haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) have not been confirmed in randomized studies.

Methods

We conducted a randomized clinical study to investigate the effects of pre-infusion (1 × 10⁶ cells/kg) MSCs on hematopoietic recovery, Epstein–Barr and cytomegalovirus infection, GVHD, and relapse in patients undergoing haplo-PBSCT. Fifty patients with acute leukemia or myelodysplastic syndrome were randomly divided into an MSC group administered 1 × 10⁶ MSCs/kg 4 to 6 hours before infusion of peripheral stem cells and a control group without MSCs.

Results

Mean platelet engraftment time was significantly faster in the MSC compared with the control group (12.28 vs 13.29 days). The mean neutrophil engraftment time was comparable in both groups (10.76 ± 2.40 vs. 10.29 ± 1.72 days). Grade II or above acute GVHD was significantly decreased in the MSC compared with the control group (12% vs. 36%). There were no significant differences in relapse rate or overall survival between the groups.

Conclusion

These results suggest that pre-infusion single-dose MSCs promote platelet engraftment and decrease severe acute GVHD without increasing relapse rate.

[Mesenchymal stem cell treatment in autoimmune diseases]

Mesenchymal stromal or stem cells (MSC) possess strong immunomodulatory properties. Due to their impressive potential to differentiate into various cell types they are capable of inducing mechanisms of tissue repair. Experimental data have demonstrated impaired MSC function in several rheumatic diseases in vitro; however, the relevance of these phenomena for the pathogenesis of rheumatic disorders has not been convincingly demonstrated. Nevertheless, allogeneic MSC transplantation (MSCT), and possibly autologous MSCT as well, could prove to be an interesting instrument for the treatment of autoimmune rheumatic diseases. The first clinical trials have demonstrated positive effects in systemic lupus erythematosus, systemic sclerosis and Sjogren's syndrome; however, questions regarding the long-term benefits and safety as well as the best source, the optimal cultivation technique and the most effective way of application of MSC are still unanswered.

Glutathione dynamics determine the therapeutic efficacy of mesenchymal stem cells for graft-versus-host disease via CREB1-NRF2 pathway

Glutathione (GSH), the most abundant nonprotein thiol functioning as an antioxidant, plays critical roles in maintaining the core functions of mesenchymal stem cells (MSCs), which are used as a cellular immunotherapy for graft-versus-host disease (GVHD). However, the role of GSH dynamics in MSCs remains elusive. Genome-wide gene expression profiling and high-throughput live-cell imaging assays revealed that CREB1 enforced the GSH-recovering capacity (GRC) of MSCs through NRF2 by directly up-regulating NRF2 target genes responsible for GSH synthesis and redox cycling. MSCs with enhanced GSH levels and GRC mediated by CREB1-NRF2 have improved self-renewal, migratory, anti-inflammatory, and T cell suppression capacities. Administration of MSCs overexpressing CREB1-NRF2 target genes alleviated GVHD in a humanized mouse model, resulting in improved survival, decreased weight loss, and reduced histopathologic damages in GVHD target organs. Collectively, these findings demonstrate the molecular and functional importance of the CREB1-NRF2 pathway in maintaining MSC GSH dynamics, determining therapeutic outcomes for GVHD treatment.

Mesenchymal stromal cells for the prophylaxis and treatment of graft-versus-host disease-a meta-analysis

Background

Graft-versus-host disease (GvHD) is the main life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT). Thirty to 80% of GvHD patients do not respond to first-line treatment and a second-line treatment is not universally established. Based on their immunomodulatory properties, mesenchymal stromal cells (MSC) have been proposed for the prevention and the treatment of GvHD in patients undergoing HSCT. Unfortunately, previous studies reported conflicting results regarding the prophylactic and therapeutic effects of MSC for GvHD. Consequently, we carried out a meta-analysis to clarify whether MSC administration can improve the dismal outcome of these patients.

Methods

We carried out a systematic review and selected studies (2004–2019) reporting data about the administration of allogeneic MSC for the prevention (n = 654 patients) or treatment of acute (n = 943 patients) or chronic (n = 76 patients) GvHD after HSCT. Our primary outcome was overall survival at the last follow-up. The secondary outcomes were the response and development of GvHD. Subgroup analyses included age, MSC dose, first infusion day after HSCT, number of organs and organ-specific involvement, acute GvHD grade (I–IV), and chronic GvHD grade (limited or extensive).

Results

Patients infused with MSC for GvHD prophylaxis showed a 17% increased overall survival (95% CI, 1.02–1.33) and a reduced incidence of acute GvHD grade IV (RR = 0.22; 95% CI, 0.06–0.81) and chronic GvHD (RR = 0.64; 95% CI, 0.47–0.88) compared with controls. Overall survival of acute GvHD patients (0.50; 95% CI, 0.41–0.59) was positively correlated with MSC dose (P = 0.0214). The overall response was achieved in 67% (95% CI, 0.61–0.74) and was complete in 39% (95% CI, 0.31–0.48) of acute patients. Organ-specific response was higher for the skin. Twenty-two percent (95% CI, 0.16–0.29) of acute patients infused with MSC developed chronic GvHD. Sixty-four percent (95% CI, 0.47–0.80) of chronic patients infused with MSC survived; the overall response was 66% (95% CI, 0.55–0.76) and was complete in 23% (95% CI 0.12–0.34) of patients.

Conclusions

Our meta-analysis indicates that allogeneic MSC could be instrumental for the prophylaxis and treatment of GvHD. Future trials should investigate the effect of the administration of MSC as an adjuvant therapy for the treatment of patients with GvHD from the onset of the disease.

Can we prevent or treat graft-versus-host disease with cellular-therapy?

Acute and chronic graft-versus-host disease (GvHD) are the most important causes of treatment-related morbidity and mortality after allogeneic hematopoietic cell transplants for various diseases. Corticosteroids are an effective therapy in only about one-half of affected individuals and new therapy options are needed. We discuss novel strategies to treat GvHD using cellular-therapy including adoptive transfer of regulatory T-cells (T_regs), mesenchymal stromal cells (MSCs), cells derived from placental tissues, invariant natural killer T-cells (iNKTs), and myeloid-derived suppressor cells (MDSCs).These strategies may be more selective than drugs in modulating GvHD pathophysiology, and may be safer and more effective than conventional pharmacologic therapies. Additionally, these therapies have not been observed to substantially compromise the graft-versus-tumor effect associated with allotransplants. Many of these strategies are effective in animal models but substantial data in humans are lacking.

Therapeutic evidence of umbilical cord-derived mesenchymal stem cell transplantation for cerebral palsy: a randomized, controlled trial

BACKGROUND

Cerebral palsy (CP) is a syndrome of childhood movement and posture disorders. Clinical evidence is still limited and sometimes inconclusive about the benefits of human umbilical cord mesenchymal stem cells (hUC-MSCs) for CP. We conducted a randomized trial to evaluate the safety and efficacy of hUC-MSC transplantation concomitant with rehabilitation in patients with CP.

METHODS

Eligible patients were allocated into the hUC-MSC group and control group. In addition to rehabilitation, the patients in the hUC-MSC group received four transfusions of hUC-MSCs intravenously, while the control group received a placebo. Adverse events (AEs) were collected for safety evaluation in the 12-month follow-up phase. Primary endpoints were assessed as activities of daily living (ADL), comprehensive function assessment (CFA), and gross motor function measure (GMFM) scales. In addition, cerebral metabolic activity was detected by 18F-FDG-PET/CT to explore the possible mechanism of the therapeutic effects. Primary endpoint data were analyzed by ANOVA using SPSS version 20.0.

RESULTS

Forty patients were enrolled, and 1 patient withdrew informed consent. Therefore, 39 patients received treatments and completed the scheduled assessments. No significant difference was shown between the 2 groups in AE incidence. Additionally, significant improvements in ADL, CFA, and GMFM were observed in the hUC-MSC group compared with the control group. In addition, the standard uptake value of 18F-FDG was markedly increased in 3 out of 5 patients from the hUC-MSC group at 12 months after transplantation.

CONCLUSIONS

Our clinical data showed that hUC-MSC transplantation was safe and effective at improving the gross motor and comprehensive function of children with CP when combined with rehabilitation. Recovery of cerebral metabolic activity might play an essential role in the improvements in brain function in patients with CP. The therapeutic window, transfusion route, and dosage in our study were considerable for reference in clinical application.

TRIAL REGISTRATION

Chictr.org.cn, ChiCTR1800016554. Registered 08 June 2018-retrospectively registered. The public title was "Randomized trial of umbilical cord-derived mesenchymal stem cells for cerebral palsy."

Effects of mesenchymal stromal cells on regulatory T cells: Current understanding and clinical relevance

The immunomodulatory potential of mesenchymal stromal cells (MSCs) and regulatory T cells (T‐reg) is well recognized by translational scientists in the field of regenerative medicine and cellular therapies. A wide range of preclinical studies as well as a limited number of human clinical trials of MSC therapies have not only shown promising safety and efficacy profiles but have also revealed changes in T‐reg frequency and function. However, the mechanisms underlying this potentially important observation are not well understood and, consequently, the optimal strategies for harnessing MSC/T‐reg cross‐talk remain elusive. Cell‐to‐cell contact, production of soluble factors, reprogramming of antigen presenting cells to tolerogenic phenotypes, and induction of extracellular vesicles (“exosomes”) have emerged as possible mechanisms by which MSCs produce an immune‐modulatory milieu for T‐reg expansion. Additionally, these two cell types have the potential to complement each other's immunoregulatory functions, and a combinatorial approach may exert synergistic effects for the treatment of immunological diseases. In this review, we critically assess recent translational research related to the outcomes and mechanistic basis of MSC effects on T‐reg and provide a perspective on the potential for this knowledge base to be further exploited for the treatment of autoimmune disorders and transplants.

Cell therapy with intravascular administration of mesenchymal stromal cells continues to appear safe: An updated systematic review and meta-analysis

BACKGROUND

Characterization of the mesenchymal stromal cell (MSC) safety profile is important as this novel therapy continues to be evaluated in clinical trials for various inflammatory conditions. Due to an increase in published randomized controlled trials (RCTs) from 2012-2019, we performed an updated systematic review to further characterize the MSC safety profile.

METHODS

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and Web of Science (to May 2018) were searched. RCTs that compared intravascular delivery of MSCs to controls in adult populations were included. Pre-specified adverse events were grouped according to: (1) immediate, (2) infection, (3) thrombotic/embolic, and (4) longer-term events (mortality, malignancy). Adverse events were pooled and meta-analyzed by fitting inverse-variance binary random effects models. Primary and secondary clinical efficacy endpoints were summarized descriptively.

FINDINGS

7473 citations were reviewed and 55 studies met inclusion criteria (n = 2696 patients). MSCs as compared to controls were associated with an increased risk of fever (Relative Risk (RR) = 2·48, 95% Confidence Interval (CI) = 1·27-4·86; I2 = 0%), but not non-fever acute infusional toxicity, infection, thrombotic/embolic events, death, or malignancy (RR = 1·16, 0·99, 1·14, 0·78, 0·93; 95% CI = 0·70-1·91, 0·81-1·21, 0·67-1·95, 0·65-0·94, 0·60-1·45; I2 = 0%, 0%, 0%, 0%, 0%). No included trials were ended prematurely due to safety concerns.

INTERPRETATIONS

MSC therapy continues to exhibit a favourable safety profile. Future trials should continue to strengthen study rigor, reporting of MSC characterization, and adverse events.

FUNDING

Stem Cell Network, Ontario Institute for Regenerative Medicine and Ontario Research Fund.

Mesenchymal Stem/Stromal Cell Production Compliant with Good Manufacturing Practice: Comparison between Bone Marrow, the Gold Standard Adult Source, and Wharton's Jelly, an Extraembryonic Source

Many clinical trials report mesenchymal stem/stromal cells (MSCs) efficacy in various indications. Therefore, standardization of MSC production becomes necessary. MSC properties are impacted by tissue origin, especially if they are from extraembryonic tissue or adult sources. For this reason, we evaluated the impact of MSC tissue origin on production. Methods: Three productions of MSC from Wharton’s Jelly (WJ) or from bone marrow (BM) were performed according to good manufacturing practice. The identity (phenotype, differentiation, and clonogenic capacities), safety (karyotype, telomerase activity, sterility, and donor qualification), and functionality (viability, mixed lymphocyte reaction) of each cell batch were analyzed. Results: Slight differences between MSC sources were observed for phenotype, telomerase activity, and clonogenic capacities. Conclusion: Both sources have made it possible to quickly and easily obtain clinical grade MSC. However, as availability of the source is thought to be essential, WJ seems more advantageous than BM.

Clinical Translation of Mesenchymal Stromal Cell Therapy for Graft Versus Host Disease

Graft versus host disease (GVHD) is a common condition in patients subjected to allogeneic hematopoietic stem cell transplantation (HSCT). The immune cells derived from the grafted stem cells attack recipient's tissues, including those from the skin, liver, eyes, mouth, lungs, gastrointestinal tract, neuromuscular system, and genitourinary tract, may lead to severe morbidity and mortality. Acute GVHD can occur within few weeks after the allogeneic cells have engrafted in the recipient while chronic GVHD may occur any time after transplant, typically within months. Although treatable by systemic corticosteroid administration, effective responses are not achieved for a significant proportion of patients, a condition associated with poor prognosis. The use of multipotent mesenchymal stromal cells (MSCs) as an alternative to treat steroid-refractory GVHD had improved last decade, but the results are still controversial. Some studies have shown improvement in the life quality of patients after MSCs treatment, while others have found no significant benefits. In addition to variations in trial design, discrepancies in protocols for MSCs isolation, characterization, and ex vivo manipulation, account for inconsistent clinical results. In this review, we discuss the immunomodulatory properties supporting the therapeutic use of MSCs in GVHD and contextualize the main clinical findings of recent trials using these cells. Critical parameters for the clinical translation of MSCs, including consistent production of MSCs according to Good Manufacturing Practices (GMPs) and informative potency assays for product quality control (QC), are addressed.

Single cell derived spheres of umbilical cord mesenchymal stem cells enhance cell stemness properties, survival ability and therapeutic potential on liver failure

Umbilical cord mesenchymal stem cells (UCMSCs) have shown great potentials in regenerative medicine for their extensive sources, multilineage differentiation potential, low immunogenicity and self-renewal ability. However, the clinical application of UCMSCs still confronts many challenges including the requirement of large quantity of cells, low survival ability in vivo and the loss of main original characteristics due to two-dimensional (2D) culture. The traditional three-dimensional (3D)-spheroid culture can mimic in vivo conditions, but still has limitations in clinical application due to large size of spheroid against direct injection and inner cell death. Based on self-renewal tenet, we produced single cell derived sphere (SCDS) of UCMSCs through combining single cell pattern on chip with 3D culture. Compared with the 2D and traditional 3D culture, SCDS culture has many advantages to meet clinical requirements, including small size, higher abilities of survival and migration, and stronger hypoxia resistance and stemness maintenance. Furthermore, SCDS culture promotes angiogenesis in UCMSCs-xenografts and displays greater therapeutic potential on acute liver failure (ALF) in vivo. Our results suggest that SCDS culture may serve as a simple and effective strategy for UCMSCs optimization to meet clinical demand.

An efficient protocol to generate placental chorionic plate-derived mesenchymal stem cells with superior proliferative and immunomodulatory properties

Background

Placenta-derived MSCs (P-MSCs) represent a promising tool for cell-based therapeutic applications. However, the increasing demand for P-MSCs in clinical trials makes high quality and large number of P-MSCs mandatory. Here, we aim to develop an efficient protocol for P-MSC isolation and culture.

Methods

The modified explant culture (MEC) method by combining an initial mild enzymatic reaction with the subsequent explant culture was developed to simultaneously produce various P-MSCs from the different regions of the placenta in serum-free medium (SFM). Its isolation efficiencies, cell yield, and proliferative capacity were compared with the conventional explant culture (EC) method. Furthermore, we determined whether functional properties of P-MSCs are affected by the used tissue-harvesting sites in terms of their proliferation, migration, and the immunomodulatory effect on macrophage.

Results

The MEC method achieved higher yield and shorter time in primary cell confluence in SFM compared with the conventional method. The harvested cells possessed the MSC characteristics and demonstrated significantly stronger proliferation ability. Importantly, MSCs derived from chorionic plate (CP-MSCs) were found to exhibit superior properties to the other P-MSCs in proliferation and migration capacity, maintaining the fetal origin over serial passages. Notably, CP-MSCs show stronger ability in regulating macrophage polarization from M1 to M2.

Conclusion

Our study developed an efficient and high-yield technique to produce high-quality P-MSCs from the placenta, hence serving as an optimal source of MSCs for clinical application.

Donor-derived CAR-T Cells Serve as a Reduced-intensity Conditioning Regimen for Haploidentical Stem Cell Transplantation in Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia: Case Report and Review of the Literature

BACKGROUND

Reduced-intensity conditioning (RIC) regimens with low tolerable toxicities have been used for allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the relapse rate by this treatment is high. Treatment of CD19 B-cell relapsed/refractory acute lymphoblastic leukemia (r/r ALL) with allogeneic chimeric antigen receptor-modified T (CAR-T) cells is safe and effective. Use of allogeneic CD19-CAR-T cells as a part of RIC regimens for treatment of r/r ALL patients with haploidentical HSCT has not been investigated yet.

CASE PRESENTATION

A 12-year-old girl with CD19 r/r ALL underwent haploidentical HSCT. The patient received fludarabine, busulfan, and cyclophosphamide combined with haploidentical donor-derived CD19-CAR-T cells as the conditioning regimen. Granulocyte colony-stimulating factor-mobilized peripheral blood stem cells and granulocyte colony-stimulating factor-mobilized bone marrow were infused on days 1 and 2, respectively. Mycophenolate mofetil and tacrolimus were administered on day 1, antithymocyte globulin was administered on days +14 and +15, and a short course of methotrexate was administered to prevent graft-versus-host disease. The time of peak CAR-T cell proliferation was detected after the first infusion of CAR-T cells on day 7. The patient's engraftment and full-donor cell engraftment were established. The disease was in complete remission with minimal residual disease, which was undetectable by flow cytometry. No graft-versus-host disease or serious cytokine-release syndrome was found.

CONCLUSIONS

Treatment of r/r ALL with RIC including CD19-CAR-T cells followed by allo-HSCT was safe and effective, which suggest that CAR-T cells can be used as a part of RIC regimens in the treatment of r/r ALL in haploidentical HSCT.

The Use of Allogeneic Mesenchymal Stem Cells in Childhood Steroid-Resistant Acute Graft-Versus-Host Disease: A Retrospective Study of a Single-Center Experience

Objective:

Steroid-resistant acute graft-versus-host disease (srAGVHD) is the most important cause of morbidity and mortality after allogeneic stem cell transplantation. There are several treatment methods available, including mesenchymal stem cell (MSC) application. The aim of this study was to evaluate the results of MSC therapy performed in children with srAGVHD.

Materials and Methods:

MSC therapy was used in our center between November 2014 and December 2017 for 22 patients who developed srAGVHD. The patients were retrospectively evaluated in terms of treatment response and survival.

Results:

After application of MSCs, complete response was obtained in 45.5% of the subjects, partial response was obtained in 13.6%, and no response was obtained in 40.9%. We found that 45.5% of the patients were alive and 54.5% had died and our treatment results were similar to those in the literature. Response to MSC treatment was found to be the only prognostic marker affecting mortality.

Conclusion:

MSC application is a treatment method that can be used safely together with other treatment methods in srAGVHD, a condition that has a high mortality rate. There are almost no acute side effects. There are also no serious long-term side effects in the literature. Prospective randomized studies are required to obtain high-quality data.

Progress of cGVHD pathogenesis from the perspective of B cells

An increasing number of physicians realize that chronic graft-versus-host disease (cGVHD) is not just dominated by T cells and that B cells also play a vital role in cGVHD development. It has been reported that altered B cell subsets, aberrant B cell signaling pathways, antibody deposition, and abnormal T-B interactions can be observed in many cGVHD patients. Studies of B cells in cGVHD development are now mainly focused on B cell subsets and GC destruction. These two aspects describe the process of B cell evolution in cGVHD patients and are associated with some original treatments. In this review, we summarize recent literature and discuss mechanisms and novel ideas of therapeutic strategies regarding the two aspects mentioned above.

Preventive infusion of donor-derived CAR-T cells after haploidentical transplantation: Two cases report

RATIONALE

Relapse is the main cause of death after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Unfortunately, there are no efficient methods to prevent relapse after allo-HSCT. Chimeric antigen receptor T (CAR-T) cells have achieved favorable outcomes in the treatment of refractory/relapsed acute lymphoblastic leukemia (ALL) because of their strong anti-leukemia activity. However, it is unclear whether the CAR-T cells constructed using viral systems can be used as preventive infusions to prevent relapse after haploidentical HSCT.

PATIENT CONCERNS

Two patients with ALL with high risk received haploidentical HSCT.

DIAGNOSES

Two patients were diagnosed with ALL with high risk.

INTERVENTIONS

Patients received preventive infusion of donor-derived CAR-T cells constructed using viral systems on day 60 after haploidentical HSCT.

OUTCOMES

The CAR-T cells were continually detected, and no graft versus host disease developed. The two patients survived with disease-free for 1 year and 6 months, respectively.

LESSONS

Preventive infusion of donor-derived CAR-T cells after haploidentical HSCT may be safe and that immunosuppressors may not affect the proliferation of CAR-T cells.

Immune Reconstitution Disorders: Spotlight on Interferons

Three decades of research in hematopoietic stem cell transplantation and HIV/AIDS fields have shaped a picture of immune restoration disorders. This manuscript overviews the molecular biology of interferon networks, the molecular pathogenesis of immune reconstitution inflammatory syndrome, and post-hematopoietic stem cell transplantation immune restoration disorders (IRD). It also summarizes the effects of thymic involution on T cell diversity, and the results of the assessment of diagnostic biomarkers of IRD, and tested targeted immunomodulatory treatments.

The role of mesenchymal stem cells in hematopoietic stem cell transplantation: prevention and treatment of graft-versus-host disease

Background

The use and effectiveness of hematopoietic stem cell transplantation (HSCT) are limited by lethal complications, i.e., acute and chronic graft-versus-host disease (aGVHD and cGVHD, respectively), in which immune cells from the donor attack healthy recipient tissues. GVHD presents both prophylactic and therapeutic challenges, and overall survival is poor. Mesenchymal stem cells (MSCs) show considerable promise in the treatment of GVHD because of their potential immunomodulatory activity. Multiple studies have been performed to explore the possible benefit of MSCs in GVHD, but the results of these studies are sometimes conflicting. Therefore, we performed a systematic review and meta-analysis to estimate the effect of MSC infusion on GVHD treatment and prevention.

Methods

We systematically searched the MEDLINE (PubMed), Cochrane Library, EMBASE, ClinicalTrials.gov, and SinoMed CBM databases to identify studies published before February 2018 involving patients with hematologic malignancies undergoing HSCT and receiving MSC-based or conventional therapy. We included studies if they reported on the outcomes of interest.

Results

Ultimately, 10 studies were selected from among 413 candidates. According to our meta-analyses, compared with conventional treatment, MSC therapy demonstrated substantial improvements in terms of complete response (CR) and overall survival for cGVHD. However, MSC therapy did not show substantial improvements in terms of engraftment, the incidence of aGVHD, relapse, death, death due to relapse, or death due to infection. Subgroup analyses showed that MSCs derived from the umbilical cord (U-MSCs) and MSC infusion after HSCT substantially improved engraftment and cGVHD incidence, whereas MSCs derived from bone marrow (B-MSCs) and MSC infusion before HSCT shows no improvement. In addition, B-MSCs and MSC infusion before HSCT tend to prolong engraftment time, as well as increase the rates of relapse and death.

Conclusions

MSC infusion can reduce cGVHD but not aGVHD incidence and showed a positive effect in patients who already had aGVHD. For GVHD prevention, the use of U-MSCs and MSC infusion after HSCT were optimal for reducing cGVHD incidence and promoting engraftment, and might help decrease the incidence rate of relapse and death. However, B-MSCs and MSC infusion before HSCT may be harmful to patients and thus require serious consideration. A lack of robust evidence, owing to the small number of studies and small sample sizes, indicates a need for further high-quality clinical trials including large numbers of patients to validate our findings.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1287-9) contains supplementary material, which is available to authorized users.

Regenerative Capacity of Adipose Derived Stem Cells (ADSCs), Comparison with Mesenchymal Stem Cells (MSCs)

Adipose tissue is now on the top one of stem cell sources regarding its accessibility, abundance, and less painful collection procedure when compared to other sources. The adipose derived stem cells (ADSCs) that it contains can be maintained and expanded in culture for long periods of time without losing their differentiation capacity, leading to large cell quantities being increasingly used in cell therapy purposes. Many reports showed that ADSCs-based cell therapy products demonstrated optimal efficacy and efficiency in some clinical indications for both autologous and allogeneic purposes, hence becoming considered as potential tools for replacing, repairing, and regenerating dead or damaged cells. In this review, we analyzed the therapeutic advancement of ADSCs in comparison to bone marrow (BM) and umbilical cord (UC)-mesenchymal stem cells (MSCs) and designed the specific requirements to their best clinical practices and safety. Our analysis was focused on the ADSCs, rather than the whole stromal vascular fraction (SVF) cell populations, to facilitate characterization that is related to their source of origins. Clinical outcomes improvement suggested that these cells hold great promise in stem cell-based therapies in neurodegenerative, cardiovascular, and auto-immunes diseases.

Regenerative Capacity of Adipose Derived Stem Cells (ADSCs), Comparison with Mesenchymal Stem Cells (MSCs)

Adipose tissue is now on the top one of stem cell sources regarding its accessibility, abundance, and less painful collection procedure when compared to other sources. The adipose derived stem cells (ADSCs) that it contains can be maintained and expanded in culture for long periods of time without losing their differentiation capacity, leading to large cell quantities being increasingly used in cell therapy purposes. Many reports showed that ADSCs-based cell therapy products demonstrated optimal efficacy and efficiency in some clinical indications for both autologous and allogeneic purposes, hence becoming considered as potential tools for replacing, repairing, and regenerating dead or damaged cells. In this review, we analyzed the therapeutic advancement of ADSCs in comparison to bone marrow (BM) and umbilical cord (UC)-mesenchymal stem cells (MSCs) and designed the specific requirements to their best clinical practices and safety. Our analysis was focused on the ADSCs, rather than the whole stromal vascular fraction (SVF) cell populations, to facilitate characterization that is related to their source of origins. Clinical outcomes improvement suggested that these cells hold great promise in stem cell-based therapies in neurodegenerative, cardiovascular, and auto-immunes diseases.

Clinical Features of Chronic Graft-Versus-Host Disease Following Haploidentical Transplantation Combined with Infusion of a Cord Blood

Our previous studies demonstrated promising outcomes after haploidentical donor transplant combined with unrelated umbilical cord blood (haplo-cord- hematopoietic stem cell transplantation [HSCT]) for hematological disorders. However, clinical profiling regarding chronic graft-versus-host disease (cGVHD) has not yet been fully described under this protocol. This study analyzed the clinical characteristics of cGVHD among 300 patients with hematological malignancies who received haplo-cord-HSCT between January 2012 and July 2016 at our center. During the follow-up, the 5-year cumulative incidence of cGVHD based on the National Institutes of Health (NIH) consensus criteria was 32.2% (95% confidence interval [CI], 28.7-35.7); the 5-year cumulative incidence of moderate to severe cGVHD was 11.4% (95% CI, 9.4-13.4). After the multivariate analysis, the GVHD overall survival (GOS) was associated with relapse, thrombocytopenia, bronchiolitis obliterans syndrome, and steroid-refractory cGVHD. The infused CD34⁺ cells (≥3.46 × 10⁶/kg) from haploidentical grafts were a protective factor affecting GOS. This study proposed a nomogram for predicting GOS using the aforementioned five variables. The concordance index was 0.877 (95% CI, 0.859-0.895) for the accuracy evaluation of the nomogram. Our results suggested that the 5-year cumulative incidence of NIH-defined cGVHD after haplo-cord-HSCT was 32.2%, and this nomogram may help clinicians select reasonable treatment strategies.

Mesenchymal stromal cells as treatment or prophylaxis for acute or chronic graft-versus-host disease in haematopoietic stem cell transplant (HSCT) recipients with a haematological condition

BACKGROUND

Recipients of allogeneic haematopoietic stem cell transplants (HSCT) can develop acute or chronic, or both forms of graft-versus-host disease (a/cGvHD), whereby immune cells of the donor attack host tissues. Steroids are the primary treatment, but patients with severe, refractory disease have limited options and a poor prognosis. Mesenchymal stromal cells (MSCs) exhibit immunosuppressive properties and are being tested in clinical trials for their safety and efficacy in treating many immune-mediated disorders. GvHD is one of the first areas in which MSCs were clinically applied, and it is important that the accumulating evidence is systematically reviewed to assess whether their use is favoured.

OBJECTIVES

To determine the evidence for the safety and efficacy of MSCs for treating immune-mediated inflammation post-transplantation of haematopoietic stem cells.

SEARCH METHODS

We searched for randomised controlled trials (RCTs) in the Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library 2018, Issue 12), MEDLINE (from 1946), Embase (from 1974), CINAHL (from 1937), Web of Science: Conference Proceedings Citation Index-Science (CPCI-S) (from 1990) and ongoing trial databases to 6 December 2018. No constraints were placed on language or publication status.

SELECTION CRITERIA

We included RCTs of participants with a haematological condition who have undergone an HSCT as treatment for their condition and were randomised to MSCs (intervention arm) or no MSCs (comparator arm), to prevent or treat GvHD. We also included RCTs which compared different doses of MSCs or MSCs of different sources (e.g. bone marrow versus cord). We included MSCs co-transplanted with haematopoietic stem cells as well as MSCs administered post-transplantation of haematopoietic stem cells.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.We employed a random-effects model for all analyses due to expected clinical heterogeneity arising from differences in participant characteristics and interventions.

MAIN RESULTS

We identified 12 completed RCTs (879 participants), and 13 ongoing trials (1532 enrolled participants planned). Of 12 completed trials, 10 compared MSCs versus no MSCs and two compared different doses of MSCs. One trial was in people with thalassaemia major, the remaining trials were for haematological malignancies. Seven trials administered MSCs to prevent GvHD, whereas five trials gave MSCs to treat GvHD.In the comparison of MSCs with no MSCs, cells were administered at a dose of between 10⁵ and 10⁷ cells/kg in either a single dose (six trials) or in multiple doses (four trials) over a period of three days to four months. The dose-comparison trials compared 2 x 10⁶ cells/kg with 8 x 10⁶ cells/kg in two infusions, or 1 x 10⁶ cells/kg with 3 x 10⁶ cells/kg in a single infusion.The median duration of follow-up in seven trials which administered MSCs prophylactically ranged from 10 to 60 months. In three trials of MSCs as treatment for aGvHD, participants were followed up for 90 or 100 days. In two trials of MSCs as treatment for cGvHD, the mean duration of follow-up was 13.4 months (MSC group) and 23.6 months (control group) in one trial, and 56 weeks in the second trial. Five trials included adults only, six trials included adults and children, and one trial included children only. In eight trials which reported the gender distribution, the percentage of females ranged from 20% to 59% (median 35.8%).The overall quality of the included studies was low: randomisation methods were poorly reported and several of the included studies were subject to a high risk of performance bias and reporting bias. One trial which started in 2008 has not been published and the progress of this trial in unknown, leading to potential publication bias. The quality of evidence was therefore low or very low for all outcomes due to a high risk of bias as well as imprecision due to the low number of overall participants, and in some cases evidence based on a single study. We found that MSCs may make little or no difference in the risk of all-cause mortality in either prophylactic trials (HR 0.85, 95% CI 0.50 to 1.42; participants = 301; studies = 5; I² = 34% ; low-quality evidence) or therapeutic trials (HR 1.12, 95% CI 0.80 to 1.56; participants = 244; studies = 1; very low-quality evidence), and no difference in the risk of relapse of malignant disease (prophylactic trials: RR 1.08, 95% CI 0.73 to 1.59; participants = 323; studies = 6; I² = 0%; low-quality evidence) compared with no MSCs. MSCs were well-tolerated, no infusion-related toxicity or ectopic tissue formation was reported. No study reported health-related quality of life. In prophylactic trials, MSCs may reduce the risk of chronic GvHD (RR 0.66, 95% CI 0.49 to 0.89; participants = 283; studies = 6; I² = 0%; low-quality evidence). This means that only 310 (95% CI 230 to 418) in every 1000 patients in the MSC arm are expected to develop chronic GvHD compared to 469 in the control arm. However, MSCs may make little or no difference to the risk of aGvHD (RR 0.86, 95% CI 0.63 to 1.17; participants = 247; studies = 6; I² = 0%; low-quality evidence). In GvHD therapeutic trials, we are very uncertain whether MSCs improve complete response of either aGvHD (RR 1.16, 95% CI 0.79 to 1.70, participants = 260, studies = 1; very low-quality evidence) or cGvHD (RR 5.00, 95%CI 0.75 to 33.21, participants = 40, studies = 1; very low-quality evidence).In two trials which compared different doses of MSCs, we found no evidence of any differences in outcomes.

AUTHORS' CONCLUSIONS

MSCs are an area of intense research activity, and an increasing number of trials have been undertaken or are planned. Despite a number of reports of positive outcomes from the use of MSCs for treating acute GvHD, the evidence to date from RCTs has not supported the conclusion that they are an effective therapy. There is low-quality evidence that MSCs may reduce the risk of cGvHD. New trial evidence will be incorporated into future updates of this review, which may better establish a role for MSCs in the prevention or treatment of GvHD.

Developing role of B cells in the pathogenesis and treatment of chronic GVHD

Chronic graft-versus-host disease (cGVHD) is a major complication affecting the long-term survival of patients after allogeneic haematopoietic stem cell transplantation. The mechanism of cGVHD is unclear, and while previous studies have primarily focused on T cells, the role of B cells in the pathogenesis of cGVHD has been less reported. However, current studies on cGVHD are increasingly focused on the important role of B cells. In this review, we will introduce the newest studies and examine the role of B cells in cGVHD in detail with respect to the following aspects: altered B cell subpopulations, aberrant B cell signalling pathways, autoantibodies and T-B cell interactions. Treatment strategies for the targeting of B cells during cGVHD will also be discussed.

Bone management in hematologic stem cell transplant recipients

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) is the treatment of choice for patients with some malignant and non-malignant hematological diseases. Advances in transplantation techniques and supportive care measures have substantially increased the number of long-term HSCT survivors. This has led to an increasing patient population suffering from the late effects of HSCT, of which, bone loss and its consequent fragility fractures lead to substantial morbidity. Altered bone health, with consequent fragility fractures, and chronic graft-versus-host disease (GVHD) are factors affecting long-term quality of life after HSCT. Hypogonadism, HSCT preparative regimens, nutritional factors, and glucocorticoids all contribute to accelerated bone loss and increased fracture risk. Management strategies should include bone mineral density examination, evaluation of clinical risk factors, and general dietary and physical activity measures. Evidence has accumulated permitting recommendations for more attentiveness to evaluation and monitoring of bone health, with appropriate application of osteoporosis pharmacotherapies to patients at increased risk of bone loss and fracture.