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

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.

Tolerising cellular therapies: what is their promise for autoimmune disease?

The current management of autoimmunity involves the administration of immunosuppressive drugs coupled to symptomatic and functional interventions such as anti-inflammatory therapies and hormone replacement. Given the chronic nature of autoimmunity, however, the ideal therapeutic strategy would be to reinduce self-tolerance before significant tissue damage has accrued. Defects in, or defective regulation of, key immune cells such as regulatory T cells have been documented in several types of human autoimmunity. Consequently, it has been suggested that the administration of ex vivo generated, tolerogenic immune cell populations could provide a tractable therapeutic strategy. Several potentially tolerogenic cellular therapies have been developed in recent years; concurrent advances in cell manufacturing technologies promise scalable, affordable interventions if safety and efficacy can be demonstrated. These therapies include mesenchymal stromal cells, tolerogenic dendritic cells and regulatory T cells. Each has advantages and disadvantages, particularly in terms of the requirement for a bespoke versus an ‘off-the-shelf’ treatment but also their suitability in particular clinical scenarios. In this review, we examine the current evidence for these three types of cellular therapy, in the context of a broader discussion around potential development pathway(s) and their likely future role. A brief overview of preclinical data is followed by a comprehensive discussion of human data.

The Use of Human Mesenchymal Stem Cells as Therapeutic Agents for the in vivo Treatment of Immune-Related Diseases: A Systematic Review

Background: One of the greatest challenges for medicine is to find a safe and effective treatment for immune-related diseases. However, due to the low efficacy of the treatment available and the occurrence of serious adverse effects, many groups are currently searching for alternatives to the traditional therapy. In this regard, the use of human mesenchymal stem cells (hMSCs) represents a great promise for the treatment of a variety of immune-related diseases due to their potent immunomodulatory properties. The main objective of this study is, therefore, to present and summarize, through a systematic review of the literature, in vivo studies in which the efficacy of the administration of hMSCs for the treatment of immune-related diseases was evaluated. Methods: The article search was conducted in PubMed/MEDLINE, Scopus and Web of Science databases. Original research articles assessing the therapeutic potential of hMSCs administration for the in vivo treatment immune-related diseases, published from 1984 to December 2017, were selected and evaluated. Results: A total of 132 manuscripts formed the basis of this systematic review. Most of the studies analyzed reported positive results after hMSCs administration. Clinical effects commonly observed include an increase in the survival rates and a reduction in the severity and incidence of the immune-related diseases studied. In addition, hMSCs administration resulted in an inhibition in the proliferation and activation of CD19⁺ B cells, CD4⁺ Th1 and Th17 cells, CD8⁺ T cells, NK cells, macrophages, monocytes, and neutrophils. The clonal expansion of both Bregs and Tregs cells, however, was stimulated. Administration of hMSCs also resulted in a reduction in the levels of pro-inflammatory cytokines such as IFN-γ, TNF-α, IL-1, IL-2, IL-12, and IL-17 and in an increase in the levels of immunoregulatory cytokines such as IL-4, IL-10, and IL-13. Conclusions: The results obtained in this study open new avenues for the treatment of immune-related diseases through the administration of hMSCs and emphasize the importance of the conduction of further studies in this area.

Reflection and observation: cell-based screening failing to detect HBV in HUMSCs derived from HBV-infected mothers underscores the importance of more stringent donor eligibility to reduce risk of transmission of infectious diseases for stem cell-based medical products

Background

In cell-based therapy, the transmission of communicable diseases imposes a substantial threat to recipients. In this study, we investigated whether cell-based screening could detect hepatitis B virus (HBV) in human umbilical cord-derived mesenchymal stem cells (HUMSCs) isolated from HBV-infected donors to understand the susceptibility of HUMSCs to HBV infection.

Methods

HBV assay was performed in HUMSCs derived from healthy and HBV-infected donors with enzyme-linked immunosorbent assay (ELISA), fluorescence quantitative PCR (FQ-PCR) assay, and droplet digital PCR (ddPCR) assay. Further, HBV DNA was assayed in HUMSCs derived from healthy donors after incubation with human sera containing a high titer of HBV using FQ-PCR.

Results

HBV antigen/antibody and DNA failed to be detected using ELISA, FQ-PCR, and ddPCR. After incubation with HBV infection sera, HBV DNA could be detected, but below the valid titer of the assay kit. The HBV DNA levels in HBV-incubated HUMSCs gradually decreased with medium change every 2 days and then significantly decreased, not even detected after passage.

Conclusions

The current cell-based screening methods could not detect HBV in HUMSCs derived from HBV-infected donors, indicating the importance of more stringent donor eligibility to reduce the risk of transmission of communicable diseases in cell-based therapy. To solve the problem of an occult HBV window period in donor eligibility determination, we recommend that the donors undergo another HBV serological test 3 months after the first serological communicable disease screening.

Efficacy and safety of mesenchymal stromal cells for the prophylaxis of chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation: a meta-analysis of randomized controlled trials

A meta-analysis of randomized controlled trials (RCTs) was conducted to evaluate the efficacy and safety of mesenchymal stromal cells (MSCs) for the prophylaxis of chronic graft-versus-host disease (cGVHD) in patients with hematological malignancies undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Six studies involving 365 patients were included. The pooled results showed that MSCs significantly reduced the incidence of cGVHD (risk ratio [RR] 0.63, 95% confidence interval [CI] 0.46 to 0.86, P = 0.004). Favorable prophylactic effects of MSCs on cGVHD were observed with umbilical cord-derived, high-dose, and late-infusion MSCs, while bone marrow-derived, low-dose, and coinfused MSCs did not confer beneficial prophylactic effects. In addition, MSC infusion did not increase the risk of primary disease relapse and infection (RR 1.02, 95% CI 0.70 to 1.50, P = 0.913; RR 0.89, 95% CI 0.44 to 1.81, P = 0.752; respectively). Moreover, there was an apparent trend toward increased overall survival (OS) in the MSC group compared with that in the control group (RR 1.13, 95% CI 0.98 to 1.29, P = 0.084). In conclusion, this meta-analysis demonstrated that MSC infusion is an effective and safe prophylactic strategy for cGVHD in patients with hematological malignancies undergoing allo-HSCT.

Bone marrow-derived CXCR4-overexpressing MSCs display increased homing to intestine and ameliorate colitis-associated tumorigenesis in mice

Background and Objective

Increasing interest has developed in the therapeutic potential of bone marrow-derived mesenchymal stem cells (MSCs) for the treatment of inflammatory bowel disease (IBD) and IBD-induced cancer. However, whether MSCs have the ability to suppress or promote tumor development remains controversial. The stromal cell-derived factor 1 (SDF-1)/C-X-C chemokine receptor type 4 (CXCR4) axis is well known to play a critical role in the homing of MSCs. In this study, we aimed to evaluate the role of CXCR4-overexpressing MSCs on the tumorigenesis of IBD.

Methods

MSCs were transduced with lentiviral vector carrying either CXCR4 or green fluorescent protein (GFP). Chemotaxis and invasion assays were used to detect CXCR4 expression. A mouse model of colitis-associated tumorigenesis was established using azoxymethane and dextran sulfate sodium (DSS). The mice were divided into three groups and then injected with phosphate buffer saline (PBS), MSC-GFP or MSC-CXCR4.

Results

Compared with the mice injected with MSC-GFP, the mice injected with MSC-CXCR4 showed relieved weight loss, longer colons, lower tumor numbers and decreased tumor load; expression of pro-inflammatory cytokines decreased, and signal transducer and activator of transcription 3 (STAT3) phosphorylation level in colon tissue was down-regulated.

Conclusion

CXCR4-overexpressing MSCs exhibited effective anti-tumor function, which may be associated with enhanced homing to inflamed intestinal tissues.

Small hypoxia-primed mesenchymal stem cells attenuate graft-versus-host disease

Mesenchymal stem cells (MSCs) are of particular interest for the treatment of immune-related diseases due to their immunosuppressive capacity. Here, we show that Small MSCs primed with Hypoxia and Calcium ions (SHC-MSCs) exhibit enhanced stemness and immunomodulatory functions for treating allogeneic conflicts. Compared with naïve cultured human umbilical cord blood-derived MSCs, SHC-MSCs were resistant to passage-dependent senescence mediated via the monocyte chemoattractant protein-1 and p53/p21 cascade and secreted large amounts of pro-angiogenic and immunomodulatory factors, resulting in suppression of T-cell proliferation. SHC-MSCs showed DNA demethylation in pluripotency, germline, and imprinted genes similarly to very small embryonic-like stem cells, suggesting a potential mutual relationship. Genome-wide DNA methylome and transcriptome analyses indicated that genes related to immune modulation, cell adhesion, and the cell cycle were up-regulated in SHC-MSCs. Particularly, polo-like kinase-1 (PLK1), zinc-finger protein-143, dehydrogenase/reductase-3, and friend-of-GATA2 play a key role in the beneficial effects of SHC-MSCs. Administration of SHC-MSCs or PLK1-overexpressing MSCs significantly ameliorated symptoms of graft-versus-host disease (GVHD) in a humanized mouse model, resulting in significantly improved survival, less weight loss, and reduced histopathologic injuries in GVHD target organs compared with naïve MSC-infused mice. Collectively, our findings suggest that SHC-MSCs can improve the clinical treatment of allogeneic conflicts, including GVHD.

Mesenchymal stromal cell exosome-enhanced regulatory T-cell production through an antigen-presenting cell-mediated pathway

BACKGROUND AIMS

The immunomodulatory property of mesenchymal stromal cell (MSC) exosomes is well documented. On the basis of our previous report that MSC exosomes increased regulatory T-cell (Treg) production in mice with allogenic skin graft but not in ungrafted mice, we hypothesize that an activated immune system is key to exosome-mediated Treg production.

METHODS

To test our hypothesis, MSC exosomes were incubated with mouse spleen CD4⁺ T cells that were activated with either anti-CD3/CD28 mAbs or allogenic antigen-presenting cell (APC)-enriched spleen CD11c⁺ cells to determine whether production of mouse CD4⁺CD25⁺ T cells or CD4⁺CD25⁺Foxp3⁺ Tregs could be induced. MSC exosomes were also administered to the lethal chimeric human-SCID mouse model of graft-versus-host disease (GVHD) in which human peripheral blood mononuclear cells were infused into irradiated NSG mice to induce GVHD.

RESULTS

We report here that MSC exosome-induced production of CD4⁺CD25⁺ T cells or CD4⁺CD25⁺Foxp3⁺ Tregs from CD4⁺ T cells activated by allogeneic APC-enriched CD11C⁺ cells but not those activated by anti-CD3/CD28 mAbs. This induction was exosome- and APC dose-dependent. In the mouse GVHD model in which GVHD was induced by transplanted human APC-stimulated human anti-mouse CD4⁺ T cell effectors, MSC exosome alleviated GVHD symptoms and increased survival. Surviving exosome-treated mice had a significantly higher level of human CD4⁺CD25⁺CD127^low/- Tregs than surviving mice treated with Etanercept, a tumor necrosis factor inhibitor.

CONCLUSIONS

MSC exosome enhanced Treg production in vitro and in vivo through an APC-mediated pathway.

Update on current research into haploidentical hematopoietic stem cell transplantation

INTRODUCTION

Haploidentical stem cell transplantation (Haplo-SCT) is currently a suitable alternative worldwide for patients with hematological diseases, who lack human leukocyte antigen (HLA)-matched siblings or unrelated donors. Areas covered: This review summarizes the advancements in Haplo-SCT in recent years, primarily focusing on the global trends of haploidentical allograft, the comparison of outcomes between Haplo-SCT and other transplantation modalities, strategies for improving clinical outcomes, including donor selection, hematopoietic reconstitution promotion, and graft-versus-host disease, and relapse prevention/management, as well as the expanded indications of Haplo-SCT, such as severe aplastic anemia, myeloma and lymphoma. Expert commentary: Haploidentical allografts, including granulocyte colony-stimulating factor-based protocol and a post-transplant cyclophosphamide-based protocol, have been the mainstream strategy for Haplo-SCT. However, there are many unanswered questions in this field.

The Effect of Mesenchymal Stem Cell-Derived Extracellular Vesicles on Hematopoietic Stem Cells Fate

Hematopoietic stem cells (HSCs) are multipotent stem cells, with self-renewal ability as well as ability to generate all blood cells. Mesenchymal stem cells (MSCs) are multipotent stem cells, with self-renewal ability, and capable of differentiating into a variety of cell types. MSCs have supporting effects on hematopoiesis; through direct intercellular communications as well as secreting cytokines, chemokines, and extracellular vesicles (EVs). Recent investigations demonstrated that some biological functions and effects of MSCs are mediated by their EVs. MSC-EVs are the cell membrane and endosomal membrane compartments, which are important mediators in the intercellular communications. MSC-EVs contain some of the molecules such as proteins, mRNA, siRNA, and miRNA from their parental cells. MSC-EVs are able to inhibit tumor, repair damaged tissue, and modulate immune system responses. MSC-EVs compared to their parental cells, may have the specific safety advantages such as the lower potential to trigger immune system responses and limited side effects. Recently some studies demonstrated the effect of MSC-EVs on the expansion, differentiation, and clinical applications of HSCs such as improvement of hematopoietic stem cell transplantation (HSCT) and inhibition of graft versus host disease (GVHD). HSCT may be the only therapeutic choice for patients who suffer from malignant and non-malignant hematological disorders. However, there are several severe side effects such GVHD that restricts the successfulness of HSCT. In this review, we will discuss the most important effects of MSCs and MSC-EVs on the improvement of HSCT, inhibition and treatment of GVHD, as well as, on the expansion of HSCs.

Optimization of MSC therapeutic strategies for improved GVHD treatment

Mesenchymal stem cells (MSCs) have a powerful immunosuppressive capacity, and they have been used to treat numerous immune diseases, such as refractory graft-versus-host disease. Nevertheless, there are conflicting clinical data. To our knowledge, MSCs from different donors do not share the same qualities and have different immunosuppressive capacities. Infused MSCs are cleared by the recipient’s immune cells or macrophages. Therefore, the MSC therapeutic strategy might be the most important factor that determines treatment success. Repeated infusions would lead to a relatively stable MSC concentration, which would benefit a sustained therapeutic effect. In this review, we focus on the quality of MSCs and the associated therapeutic strategy, as well as other potential variables affecting their utility as a cellular pharmaceutical.

Specific Adoptive Cellular Immunotherapy in Allogeneic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) represents a treatment option for a diversity of advanced hematopoietic malignancies providing hope for long-term responses especially due to immunogenic effects associated with the treatment modality. Despite respectable progress in the field, relapses and/or opportunistic infections are major reasons for the high treatment-related mortality. However, a number of novel immunotherapeutic approaches using defined cell populations have been developed to directly target residual malignant cells as well as defined infectious diseases. We here provide an overview of current adoptive cellular immunotherapies in the context of allo-HSCT and close with an outlook on new directions within the field.

Umbilical cord mesenchymal stromal cell transplantations: A systemic analysis of clinical trials

The advances and success of umbilical cord-derived mesenchymal stromal cells (UC-MSCs) in experimental disease animal models have fueled the development of targeted therapies in humans. The therapeutic potential of allogeneic transplantation of UC-MSCs has been under examination since 2009. The purpose of this systematic analysis was to review the published results, limitations and obstacles for UC-MSC transplantation. An extensive search strategy was applied to the published literature, 93 peer-reviewed full-text articles and abstracts were found published by early August 2017 that investigated the safety, efficacy and feasibility of UC-MSCs in 2001 patients with 53 distinct pathologies including many systemic/local, acute/chronic conditions. Few data were extracted from the abstracts and/or Chinese-written articles (n = 7, 8%). Importantly, no long-term adverse effects, tumor formation or cell rejection were reported. All studies noted certain degrees of therapeutic benefit as evidenced by clinical symptoms and/or laboratory findings. Thirty-seven percent (n = 34) of studies were found published as a single case (n = 10; 11%) or 2-10 case reports (n = 24; 26%) with no control group. Due to the nature of many stem cell-based studies, the majority of patients also received conventional therapy regimens, which obscured the pure efficacy of the cells transplanted. Randomized, blind, phase 1/2 trials with control groups (placebo-controlled) showed more plausible results. Given that most UC-MSC trials are early phase, the internationally recognized cell isolation and preparation standards should be extended to future phase 2/3 trials to reach more convincing conclusions regarding the safety and efficacy of UC-MSC therapies.

Mesenchymal stromal cells and autoimmunity

Mesenchymal stromal cells (MSCs) are committed progenitors of mesodermal origin that are found virtually in every organ and exhibit multilineage differentiation into osteocytes, adipocytes and chondrocytes. MSCs also mediate a wide spectrum of immunoregulatory activities that usually dampen innate and adaptive immune responses. These features have attracted interest in the perspective of developing novel cell therapies for autoimmune disease. However, depending on the microenvironmental conditions, MSCs may show a plastic behavior and switch to an immunostimulatory phenotype. After thorough characterization of the effects of MSCs on the immune system, MSC cell therapy has been tested in animal models of autoimmunity using different cell sources, protocols of in vitro expansion and routes and schedules of administration. The pre-clinical results have been encouraging in some models [e.g. Crohn's disease (CD), multiple sclerosis] and heterogeneous in others (e.g. graft-versus-host disease, systemic lupus erythematosus, rheumatoid arthritis). Clinical trials have been carried out and many are ongoing. As discussed, the results obtained are too preliminary to draw any conclusion, with the only exception of topical administration of MSCs in CD that has proven efficacious. The mechanism of action of infused MSCs is still under investigation, but the apparent paradox of a therapeutic effect achieved in spite of the very low number of cells reaching the target organ has been solved by the finding that MSC-derived extracellular vesicles (EVs) closely mimic the therapeutic activity of MSCs in pre-clinical models. These issues are critically discussed in view of the potential clinical use of MSC-derived EVs.

Regulatory B cells promote graft-versus-host disease prevention and maintain graft-versus-leukemia activity following allogeneic bone marrow transplantation

Regulatory B cells (Bregs) are involved in the pathogenesis of graft-versus-host disease (GVHD). However, whether Bregs can alleviate acute GVHD without compromising graft-versus-leukemia (GVL) effects remains unclear. Here, we evaluated the role of Bregs in acute GVHD and GVL activity in both a mouse model and a clinical cohort study. In the acute GVHD mouse model, co-transplantation of Bregs prevents onset through inhibiting Th1 and Th17 differentiation and expanding regulatory T cells. In the GVL mouse model, Bregs contributed to the suppression of acute GVHD but had no adverse effect on GVL activity. In the clinical cohort study, a higher dose of Bregs in allografts was associated with a lower cumulative incidence of acute GVHD but not with increased risk of relapse. Our data demonstrate that Bregs can prevent acute GVHD and maintain GVL effects and suggest that Bregs have potential as a novel strategy for acute GVHD alleviation.

Umbilical Cord-derived Mesenchymal Stem Cells Instruct Monocytes Towards an IL10-producing Phenotype by Secreting IL6 and HGF

Human UC-MSCs are regarded as an attractive alternative to BM-MSCs for clinical applications due to their easy preparation, higher proliferation and lower immunogenicity. However, the mechanisms underlying immune suppression by UC-MSCs are still unclear. We studied the mechanism of inhibition by UC-MSCs during the differentiation of monocytes into DCs and focused on the specific source and the role of the involved cytokines. We found that UC-MSCs suppressed monocyte differentiation into DCs and instructed monocytes towards other cell types, with clear decreases in the expression of co-stimulatory molecules, in the secretion of inflammatory factors and in allostimulatory capacity. IL6, HGF and IL10 might be involved in this process because they were detected at higher levels in a coculture system. UC-MSCs produce IL-6 and HGF, and neutralization of IL-6 and HGF reversed the suppressive effect of UC-MSCs. IL10 was not produced by UC-MSCs but was exclusively produced by monocytes after exposure to UC-MSCs, IL-6 or HGF. In summary, we found that the UC-MSC-mediated inhibitory effect was dependent on IL6 and HGF secreted by UC-MSCs and that this effect induced monocyte-derived cells to produce IL10, which might indirectly strengthen the suppressive effect of UC-MSCs.

Novel targets in the treatment of chronic graft-versus-host disease

Despite advances that have improved survival after allogeneic hematopoietic stem cell transplantation (HCT), chronic graft-versus-host disease (GVHD) remains a leading cause of late morbidity and mortality after transplant. Current treatment options show limited efficacy in steroid-refractory disease, and there exists a paucity of robust data to guide management decisions. Lack of United States Food and Drug Administration (FDA)- or European Medicines Agency (EMA)-approved agents in GVHD underscore the importance of developing novel therapies. Better understanding of the biology of chronic GVHD has provided novel targets for treatment, and structured guidelines in diagnosis and in clinical trial design have provided a common language and pathways for research in this area. These, combined with the surge of drug development in Oncology and Immunology, are factors that have contributed to the accelerating field of drug development and clinical research in chronic GVHD. In these exciting times, it is possible to foresee long awaited advances in the treatment of this devastating complication of HCT. This review will summarize the ongoing clinical development for novel therapies in chronic GVHD.

Tolerance in Kidney Transplantation: What Is on the B Side?

Regulatory B cells (Breg) are in the spotlight for their role in immune homeostasis maintenance and tolerance achievement as in the last years the correlation with functional and increased Breg numbers in autoimmune diseases and transplantation has been extensively proven. Their study is, however, in its infancy with still little knowledge and consensus on their origin, phenotype, and mechanism of action. All this hampers the pursuit of an effective Breg induction method for therapeutic purposes. In this review we aim to summarize the studies on human Breg and their implication in kidney transplantation and to further discuss the issues surrounding therapeutic applications of this cell subset.