Human Amniotic Mesenchymal Stem Cells Inhibit aGVHD by Regulating Balance of Treg and T Effector Cells

Distinct biological characteristics of mesenchymal stem cells separated from different components of human placenta

Mesenchymal stem cells (MSCs) have tremendous potential in cell therapy and regenerative medicine. The placenta-derived MSCs (PMSCs) are becoming favorable sources as they are ethically preferable and rich in MSCs. Although several subgroups of PMSCs have been identified from human term placenta, optimal sources for specific clinical applications remain to be elucidated. This study aimed to isolate MSCs from various components of the placenta, and compare their biological characteristics, including morphology, proliferation, immunophenotype, differentiation potential, growth factor and cytokine secretion, and immunomodulatory properties. Finally, four distinct groups of PMSCs were isolated from the placenta: amniotic membrane-derived MSCs (AM-MSCs), chorionic membrane-derived MSCs (CM-MSCs), chorionic plate-derived MSCs (CP-MSCs), and chorionic villi-derived MSCs (CV-MSCs). The results showed that CV-MSCs had good proliferation ability, and were easier to induce osteogenic and chondrogenic differentiation; CP-MSCs exhibited the strongest inhibitory effect on the proliferation of activated T cells, secreted high levels of EGF and IL-6, and could well differentiate into osteoblasts, adipocytes, and chondroblasts; AM-MSCs showed good growth dynamics in the early generations, were able to grow at high density, and tended to induce differentiation into osteogenic and neural lineages. These findings may provide novel evidence for the selection of seed cells in clinical application.

Human Amniotic Membrane-Derived Mesenchymal Stem Cells Prevent Acute Graft-Versus-Host Disease in an Intestinal Microbiome-Dependent Manner

Acute graft-versus-host disease (aGVHD) represents a fatal severe complication after allogeneic hematopoietic stem cell transplantation. As a promising cell therapeutic strategy of aGVHD, the mechanism of mesenchymal stem cells (MSC) to ameliorate aGVHD has not been fully clarified, especially in the field of intestinal homeostasis including the intestinal microbiome involved in the pathogenesis of aGVHD. The present study aimed to explore the effect of MSC on intestinal homeostasis including the intestinal barrier and intestinal microbiome and its metabolites, as well as the role of intestinal microbiome in the preventive process of hAMSCs ameliorating aGVHD. The preventive effects of human amniotic membrane-derived MSC (hAMSCs) was assessed in humanized aGVHD mouse models. Immunohistochemistry and RT-qPCR were used to evaluate intestinal barrier function. The 16S rRNA sequencing and targeted metabolomics assay were performed to observe the alternation of intestinal microbiome and the amounts of medium-chain fatty acids (MCFAs) and short-chain fatty acids (SCFAs), respectively. Flow cytometry was performed to analyze the frequencies of T immune cells. Through animal experiments, we found that hAMSCs had the potential to prevent aGVHD. HAMSCs could repair the damage of intestinal barrier structure and function, as well as improve the dysbiosis of intestinal microbiome induced by aGVHD, and meanwhile, upregulate the concentration of metabolites SCFAs, so as to reshape intestinal homeostasis. Gut microbiota depletion and fecal microbial transplantation confirmed the involvement of intestinal microbiome in the preventive process of hAMSCs on aGVHD. Our findings showed that hAMSCs prevented aGVHD in an intestinal microbiome-dependent manner, which might shed light on a new mechanism of hAMSCs inhibiting aGVHD and promote the development of new prophylaxis regimes for aGVHD prevention.

The efficiency of human umbilical cord mesenchymal stem cells as a salvage treatment for steroid-refractory acute graft-versus-host disease

Acute graft-versus-host disease (aGVHD) is a life-threatening complication after hematopoietic stem cell transplantation (HSCT) and is primarily treated with steroids. However, there is no standard treatment for steroid-refractory acute graft-versus-host disease (SR-aGVHD). Although mesenchymal stem cells (MSCs) have proven effective for SR-aGVHD, few reports have focused on human umbilical cord blood-derived MSCs (hUCB-MSCs). Here, we report on the efficiency of hUCB-MSCs as the salvage therapy for SR-aGVHD in 54 patients. The overall response rate (ORR) reached 59.3% (32/54) 28 days later. Twenty-four patients achieved complete remission (CR), and 8 achieved partial remission (PR). The median follow-up time after the initiation of hUCB-MSC treatment was 19.3 (0.6-59.0) months. The probability of overall survival (OS) and progression-free survival (PFS) was 60.9% (47.4-74.4%, 95% CI) and 58.8% (45.3-72.3%, 95% CI), respectively, while that of GVHD/relapse-free survival (GRFS) was only 30.8% (17.86-43.74%, 95% CI). Multivariate analysis revealed that response on Day 28 was an independent favorable prognostic factor (OS, P < 0.001; PFS, P < 0.001; GRFS, P = 0.001), but an age of ≥ 18 years suggested an unfavorable long-term prognosis (OS, P < 0.001; PFS, P < 0.001; GRFS, P = 0.003). In addition, liver involvement was adversely associated with PFS (P = 0.021) and GRFS (P = 0.009). An infused MNC ≥ 8.66 × 108/kg was also detrimental to GRFS (P = 0.031). Collectively, our results support hUCB-MSCs as an effective treatment for SR-aGVHD.

Therapeutic Effects of HLA-G5 Overexpressing hAMSCs on aGVHD After Allo-HSCT: Involving in the Gut Microbiota at the Intestinal Barrier

Background

Acute graft-versus-host disease (aGVHD) initiated by intestinal barrier dysfunction and gut microbiota dysbiosis, remains one of the main obstacles for patients undergoing allogenic hematopoietic stem cell transplantation (allo-HSCT) to achieve good prognosis. Studies have suggested that mesenchymal stem cells (MSCs) can suppress immune responses and reduce inflammation, and human leukocyte antigen-G5 (HLA-G5) plays an important role in the immunomodulatory effects of MSCs, but very little is known about the potential mechanisms in aGVHD. Thus, we explored the effect of HLA-G5 on the immunosuppressive properties of human amnion MSCs (hAMSCs) and demonstrated its mechanism related to the gut microbiota at the intestinal barrier in aGVHD.

Methods

Patients undergoing allo-HSCT were enrolled to detect the levels of plasma-soluble HLA-G (sHLA-G) and regulatory T cells (Tregs). Humanized aGVHD mouse models were established and treated with hAMSCs or HLA-G5 overexpressing hAMSCs (ov-HLA-G5-hAMSCs) to explore the mechanism of HLA-G5 mediated immunosuppressive properties of hAMSCs and the effect of ov-HLA-G5-hAMSCs on the gut microbiota at the intestinal barrier in aGVHD.

Results

The plasma levels of sHLA-G on day +30 after allo-HSCT in aGVHD patients were lower than those in patients without aGVHD, and the sHLA-G levels were positively correlated with Tregs percentages. ov-HLA-G5-hAMSCs had the potential to inhibit the expansion of CD3+CD4+ T and CD3+CD8+ T cells and promote Tregs differentiation, suppress proinflammatory cytokine secretion but promote anti-inflammatory cytokines release. Besides, ov-HLA-G5-hAMSCs also could reverse the intestinal barrier dysfunction and gut microbiota dysbiosis in aGVHD.

Conclusion

We demonstrated that HLA-G might work with Tregs to create a regulatory network together to reduce the occurrence of aGVHD. HLA-G5 mediated hAMSCs to exert higher immunosuppressive properties in vivo and reverse the immune imbalance caused by T lymphocytes and cytokines. Furthermore, HLA-G5 overexpressing hAMSCs could restore gut microbiota and intestinal barriers, thereby ameliorating aGVHD.

Human Amniotic Mesenchymal Stem Cells Alleviate aGVHD after allo-HSCT by Regulating Interactions between Gut Microbiota and Intestinal Immunity

Acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation poses one of the most vexing challenges. Gut microbiota dysbiosis can proceed aGVHD and mesenchymal stem cells (MSCs) have promising therapeutic potential for aGVHD. However, whether hAMSCs affect the gut microbiota during aGVHD mitigation remains unknown. Accordingly, we sought to define the effects and underlying mechanisms of human amniotic membrane-derived MSCs (hAMSCs) regulating the gut microbiota and intestinal immunity in aGVHD. By establishing humanized aGVHD mouse models and hAMSCs treatment, we found that hAMSCs significantly ameliorated aGVHD symptoms, reversed the immune imbalance of T cell subsets and cytokines, and restored intestinal barrier. Moreover, the diversity and composition of gut microbiota were improved upon treatment with hAMSCs. Spearman's correlation analysis showed that there was a correlation between the gut microbiota and tight junction proteins, immune cells as well as cytokines. Our research suggested that hAMSCs alleviated aGVHD by promoting gut microbiota normalization and regulating the interactions between the gut microbiota and intestinal barrier, immunity.

Insights into mechanisms of graft-versus-host disease through humanised mouse models

Graft-versus-host disease (GVHD) is a major complication that occurs following allogeneic haematopoietic stem cell transplantation (HSCT) for the treatment of haematological cancers and other blood-related disorders. GVHD is an inflammatory disorder, where the transplanted donor immune cells can mediate an immune response against the recipient and attack host tissues. Despite over 60 years of research, broad-range immune suppression is still used to prevent or treat GVHD, leading to an increased risk of cancer relapse and infection. Therefore, further insights into the disease mechanisms and development of predictive and prognostic biomarkers are key to improving outcomes and reducing GVHD development following allogeneic HSCT. An important preclinical tool to examine the pathophysiology of GVHD and to understand the key mechanisms that lead to GVHD development are preclinical humanised mouse models. Such models of GVHD are now well-established and can provide valuable insights into disease development. This review will focus on models where human peripheral blood mononuclear cells are injected into immune-deficient non-obese diabetic (NOD)-scid-interleukin-2(IL-2)Rγ mutant (NOD-scid-IL2Rγ^null) mice. Humanised mouse models of GVHD can mimic the clinical setting for GVHD development, with disease progression and tissues impacted like that observed in humans. This review will highlight key findings from preclinical humanised mouse models regarding the role of donor human immune cells, the function of cytokines and cell signalling molecules and their impact on specific target tissues and GVHD development. Further, specific therapeutic strategies tested in these preclinical models reveal key molecular pathways important in reducing the burden of GVHD following allogeneic HSCT.

Mesenchymal Stem Cells and Their Small Extracellular Vesicles as Crucial Immunological Efficacy for Hepatic Diseases

Mesenchymal stem cell small extracellular vesicles (MSC-sEVs) are a priority for researchers because of their role in tissue regeneration. sEVs act as paracrine factors and carry various cargos, revealing the state of the parent cells and contributing to cell–cell communication during both physiological and pathological circumstances. Hepatic diseases are mainly characterized by inflammatory cell infiltration and hepatocyte necrosis and fibrosis, bringing the focus onto immune regulation and other regulatory mechanisms of MSCs/MSC-sEVs. Increasing evidence suggests that MSCs and their sEVs protect against acute and chronic liver injury by inducing macrophages (MΦ) to transform into the M2 subtype, accelerating regulatory T/B (Treg/Breg) cell activation and promoting immunosuppression. MSCs/MSC-sEVs also prevent the proliferation and differentiation of T cells, B cells, dendritic cells (DCs), and natural killer (NK) cells. This review summarizes the potential roles for MSCs/MSC-sEVs, including immunomodulation and tissue regeneration, in various liver diseases. There is also a specific focus on the use of MSC-sEVs for targeted drug delivery to treat hepatitis.

A comparison of isolation and culture protocols for human amniotic mesenchymal stem cells

The successful translation of mesenchymal stem cells (MSCs) from bench to bedside is predicated upon their regenerative capabilities and immunomodulatory potential. Many challenges still exist in making MSCs a viable and cost-effective therapeutic option, due in part to the challenges of sourcing MSCs from adult tissues and inconsistencies in the characterization of MSCs. In many cases, adult MSC collection is an invasive procedure, and ethical concerns and age-related heterogeneity further complicate obtaining adult tissue derived MSCs at the scales needed for clinical applications. Alternative adult sources, such as post-partum associated tissues, offer distinct advantages to overcome these challenges. However, successful therapeutic applications rely on the efficient ex-vivo expansion of the stem cells while avoiding any culture-related phenotypic alterations, which requires optimized and standardized isolation, culture, and cell preservation methods. In this review, we have compared the isolation and culture methods for MSCs originating from the human amniotic membrane (hAMSCs) of the placenta to identify the elements that support the extended subculture potential of hAMSCs without compromising their immune-privileged, pluripotent regenerative potential.Abbreviations:AM: Human amniotic membrane; ASCs: Adipose tissue-derived stem cells; BM-MSCs: Bone marrow-mesenchymal stem cells; DMEM: Dulbecco's modified eagle medium; DT: Doubling time; EMEM: Eagle's modified essential medium; ESCM: Embryonic stem cell markers; ESCs: Embryonic stem cells; hAECs: Human amniotic epithelial cells; hAMSCs: Human amniotic mesenchymal stem cells; HLA: Human leukocyte antigen; HM: Hematopoietic markers; IM: Immunogenicity markers; MHC: Major histocompatibility complex; MSCs: Mesenchymal stem cells; MCSM: Mesenchymal cell surface markers; Nanog: NANOG homeobox; Oct: Octamer binding transcription factor 4; P: Passage; PM: Pluripotency markers; STRO-1: Stromal precursor antigen-1; SCP: Subculture potential; Sox-2: Sry-related HMG box gene 2; SSEA-4: Stage-specific embryonic antigen; TRA: Tumor rejection antigen.