Advances in mesenchymal stem cell therapy for immune and inflammatory diseases: Use of cell-free products and human pluripotent stem cell-derived mesenchymal stem cells

Extraembryonic Mesenchymal Stromal/Stem Cells in Liver Diseases: A Critical Revision of Promising Advanced Therapy Medicinal Products

Liver disorders have been increasing globally in recent years. These diseases are associated with high morbidity and mortality rates and impose high care costs on the health system. Acute liver failure, chronic and congenital liver diseases, as well as hepatocellular carcinoma have been limitedly treated by whole organ transplantation so far. But novel treatments for liver disorders using cell-based approaches have emerged in recent years. Extra-embryonic tissues, including umbilical cord, amnion membrane, and chorion plate, contain multipotent stem cells. The pre-sent manuscript discusses potential application of extraembryonic mesenchymal stromal/stem cells, focusing on the management of liver diseases. Extra-embryonic MSC are characterized by robust and constitutive anti-inflammatory and anti-fibrotic properties, indicating as therapeutic agents for inflammatory conditions such as liver fibrosis or advanced cirrhosis, as well as chronic inflammatory settings or deranged immune responses.

Intravenous infusion of small umbilical cord mesenchymal stem cells could enhance safety and delay retinal degeneration in RCS rats

Background

Human umbilical cord mesenchymal stem cells (UCMSCs) transplantation is a promising therapy for the treatment of retinitis pigmentosa (RP). However, intravenously infused cells may be blocked in the lung, increasing the risk of vascular obstruction, which needs to be optimized to further improve safety and efficacy.

Methods

We derived small UCMSCs (S-UCMSCs) from filtering UCMSCs with a 10-μm filter, and compared with UCMSCs by flow cytometry, directional differentiation culture and transcriptome sequencing. Then the S-UCMSCs and UCMSCs were intravenously infused in the Royal College Surgeons (RCS) rats to evaluate the safety and the efficacy.

Results

The diameter of S-UCMSCs ranged from 5.568 to 17.231 μm, with an average diameter of 8.636 ± 2.256 μm, which was significantly smaller than that of UCMSCs. Flow cytometry, immunofluorescence and transcriptome sequencing demonstrated that the S-UCMSCs and UCMSCs were the same kind of MSCs, and the S-UCMSCs were more proliferative. After the S-UCMSCs and UCMSCs were intravenously infused into the Royal College of Surgeons (RCS) rats at a dose of 1 × 10⁶ cells/rat, the S-UCMSCs blocked in the lungs were significantly fewer and disappeared more quickly than UCMSCs. The b wave of the flash electroretinogram was improved at 7 d, and the retinal outer nuclear layer thickness was thicker at 7 d and 14 d. The expression level of inflammation was inhibited, and the expression level of neurotrophic factors was upregulated in the retina and serum after transplantation.

Conclusions

S-UCMSCs intravenous infusion was safer than UCMSCs and could delay retinal degeneration and protect visual function in RCS rats, which may be a preferable therapeutic approach for RP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-02171-3.

Pathogenic and Potential Therapeutic Roles of Exosomes Derived From Immune Cells in Liver Diseases

Liver diseases, such as viral hepatitis, alcoholic hepatitis and cirrhosis, nonalcoholic steatohepatitis, and hepatocellular carcinoma place a heavy burden on many patients worldwide. However, the treatment of many liver diseases is currently insufficient, and the treatment may be associated with strong side effects. Therapies for liver diseases targeting the molecular and cellular levels that minimize adverse reactions and maximize therapeutic effects are in high demand. Immune cells are intimately involved in the occurrence, development, and prognosis of liver diseases. The immune response in the liver can be suppressed, leading to tolerance in homeostasis. When infection or tissue damage occurs, immunity in the liver is activated rapidly. As small membrane vesicles derived from diverse cells, exosomes carry multiple cargoes to exert their regulatory effects on recipient cells under physiological or pathological conditions. Exosomes from different immune cells exert different effects on liver diseases. This review describes the biology of exosomes and focuses on the effects of exosomes from different immune cells on pathogenesis, diagnosis, and prognosis and their therapeutic potential in liver diseases.

The Role of SIRT3 in the Osteoporosis

SIRT3 is an NAD⁺-dependent deacetylase in the mitochondria with an extensive ability to regulate mitochondrial morphology and function. It has been reported that SIRT3 participates in the occurrence and development of many aging-related diseases. Osteoporosis is a common aging-related disease characterized by decreased bone mass and fragility fractures, which has caused a huge burden on society. Current research shows that SIRT3 is involved in the physiological processes of senescence of bone marrow mesenchymal stem cells (BMSCs), differentiation of BMSCs and osteoclasts. However, the specific effects and mechanisms of SIRT3 in osteoporosis are not clear. In the current review, we elaborated on the physiological functions of SIRT3, the cell types involved in bone remodeling, and the role of SIRT3 in osteoporosis. Furthermore, it also provided a theoretical basis for SIRT3 as a therapeutic target for osteoporosis.

Increasing the Therapeutic Efficacy of Extracellular Vesicles From the Antigen-Specific Antibody and Light Chain Perspective

Due to their exceptional properties, extracellular vesicles (EVs) receive special attention as next generation biotherapeutics and vehicles for drug delivery. However, despite having many advantages over cell-based therapies, EVs usually exert lower therapeutic efficacy. This results from a number of hurdles that are faced by the EV-based approaches. Administered EVs could be rapidly cleared by the mononuclear phagocytes as well as can randomly distribute within various tissues, making tissue penetration and cell targeting insufficient. However, recent research findings imply that these limitations could be overcome with the use of antigen-specific antibodies and light chains. Major histocompatibility complex (MHC) class II-expressing EVs have been shown to form aggregates after co-incubation with antigen-specific antibodies, which greatly enhanced their biological efficacy. On the other hand, EVs could be coated with antibody light chains of chosen specificity to direct them towards desired target cell population. Both findings open up a promising perspective to achieve the highest efficacy of the EV-based approaches. Herein we discuss the opportunities for enhancing extracellular vesicle’s biological activity by using specific antibodies and light chains in the context of the challenges faced by such therapeutic approach.

The Latest Developments in Immunomodulation of Mesenchymal Stem Cells in the Treatment of Intrauterine Adhesions, Both Allogeneic and Autologous

Intrauterine adhesion (IUA) is an endometrial fibrosis disease caused by repeated operations of the uterus and is a common cause of female infertility. In recent years, treatment using mesenchymal stem cells (MSCs) has been proposed by many researchers and is now widely used in clinics because of the low immunogenicity of MSCs. It is believed that allogeneic MSCs can be used to treat IUA because MSCs express only low levels of MHC class I molecules and no MHC class II or co-stimulatory molecules. However, many scholars still believe that the use of allogeneic MSCs to treat IUA may lead to immune rejection. Compared with allogeneic MSCs, autologous MSCs are safer, more ethical, and can better adapt to the body. Here, we review recently published articles on the immunomodulation of allogeneic and autologous MSCs in IUA therapy, with the aim of proving that the use of autologous MSCs can reduce the possibility of immune rejection in the treatment of IUAs.

Safety and Seroconversion of Immunotherapies against SARS-CoV-2 Infection: A Systematic Review and Meta-Analysis of Clinical Trials

Clinical trials evaluating the safety and antibody response of strategies to manipulate prophylactic and therapeutic immunity have been launched. We aim to evaluate strategies for augmentation of host immunity against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. We searched clinical trials registered at the National Institutes of Health by 25 May 2021 and conducted analyses on inoculated populations, involved immunological processes, source of injected components, and trial phases. We then searched PubMed, Embase, Scopus, and the Cochrane Central Register of Controlled Trials for their corresponding reports published by 25 May 2021. A bivariate, random-effects meta-analysis was used to derive the pooled estimate of seroconversion and adverse events (AEs). A total of 929,359 participants were enrolled in 389 identified trials. The working mechanisms included heterologous immunity, active immunity, passive immunity, and immunotherapy, with 62.4% of the trials on vaccines. A total of 9072 healthy adults from 27 publications for 22 clinical trials on active immunity implementing vaccination were included for meta-analyses. The pooled odds ratios (ORs) of seroconversion were 13.94, 84.86, 106.03, and 451.04 (all p < 0.01) for vaccines based on protein, RNA, viral vector, and inactivated virus, compared with that of respective placebo/control treatment or pre-vaccination sera. The pooled ORs for safety, as defined by the inverse of systemic adverse events (AEs) were 0.53 (95% CI = 0.27–1.05; p = 0.07), 0.35 (95% CI = 0.16–0.75; p = 0.007), 0.32 (95% CI = 0.19–0.55; p < 0.0001), and 1.00 (95% CI = 0.73–1.36; p = 0.98) for vaccines based on protein, RNA, viral vector, and inactivated virus, compared with that of placebo/control treatment. A paradigm shift from all four immune-augmentative interventions to active immunity implementing vaccination was observed through clinical trials. The efficacy of immune responses to neutralize SARS-CoV-2 for these vaccines was promising, although systemic AEs were still evident for RNA-based and viral vector-based vaccines.

Allogeneic vs. autologous mesenchymal stem/stromal cells in their medication practice

Mesenchymal stem/stromal cell (MSC)-based therapeutics is already available for treatment of a range of diseases or medical conditions. Autologous or allogeneic MSCs obtained from self or donors have their own advantages and disadvantages in their medical practice. Therapeutic benefits of using autologous vs. allogeneic MSCs are inconclusive. Transplanted MSCs within the body interact with their physical microenvironment or niche, physiologically or pathologically, and such cells in a newly established tissue microenvironment may be impacted by the pathological harmful environmental factors to alter their unique biological behaviors. Meanwhile, a temporary microenvironment/niche may be also altered by the resident or niche-surrounding MSCs. Therefore, the functional plasticity and heterogeneity of MSCs caused by different donors and subpopulations of MSCs may result in potential uncertainty in their safe and efficacious medical practice. Acknowledging a connection between MSCs' biology and their existing microenvironment, donor-controlled clinical practice for the long-term therapeutic benefit is suggested to further consider minimizing MSCs potential harm for MSC-based individual therapies. In this review, we summarize the advantages and disadvantages of autologous vs. allogeneic MSCs in their therapeutic applications. Among other issues, we highlight the importance of better understanding of the various microenvironments that may affect the properties of niche-surrounding MSCs and discuss the clinical applications of MSCs within different contexts for treatment of different diseases including cardiomyopathy, lupus and lupus nephritis, diabetes and diabetic complications, bone and cartilage repair, cancer and tissue fibrosis.

Therapeutic Implications of Mesenchymal Stromal Cells and Their Extracellular Vesicles in Autoimmune Diseases: From Biology to Clinical Applications

Mesenchymal stromal cells (MSCs) are perivascular multipotent stem cells originally identified in the bone marrow (BM) stroma and subsequently in virtually all vascularized tissues. Because of their ability to differentiate into various mesodermal lineages, their trophic properties, homing capacity, and immunomodulatory functions, MSCs have emerged as attractive candidates in tissue repair and treatment of autoimmune disorders. Accumulating evidence suggests that the beneficial effects of MSCs may be primarily mediated via a number of paracrine-acting soluble factors and extracellular vesicles (EVs). EVs are membrane-coated vesicles that are increasingly being acknowledged as playing a key role in intercellular communication via their capacity to carry and deliver their cargo, consisting of proteins, nucleic acids, and lipids to recipient cells. MSC-EVs recapitulate the functions of the cells they originate, including immunoregulatory effects but do not seem to be associated with the limitations and concerns of cell-based therapies, thereby emerging as an appealing alternative therapeutic option in immune-mediated disorders. In the present review, the biology of MSCs will be outlined and an overview of their immunomodulatory functions will be provided. In addition, current knowledge on the features of MSC-EVs and their immunoregulatory potential will be summarized. Finally, therapeutic applications of MSCs and MSC-EVs in autoimmune disorders will be discussed.

Transition of clinical and basic studies on liver cirrhosis treatment using cells to seek the best treatment

The liver is a highly regenerative organ; however, its regeneration potential is reduced by chronic inflammation with fibrosis accumulation, leading to cirrhosis. With an aim to tackle liver cirrhosis, a life-threatening disease, trials of autologous bone marrow cell infusion (ABMi) therapy started in 2003. Clinical studies revealed that ABMi attenuated liver fibrosis and improved liver function in some patients; however, this therapy has some limitations such as the need of general anesthesia. Following ABMi therapy, studies have focused on specific cells such as mesenchymal stromal cells (MSCs) from a variety of tissues such as bone marrow, adipose tissue, and umbilical cord tissues. Particularly, studies have focused on gaining mechanistic insights into MSC distribution and effects on immune cells, especially macrophages. Several basic studies have reported the use of MSCs for liver cirrhosis models, while a number of clinical studies have used autologous and allogeneic MSCs; however, there are only a few reports on the obvious substantial effect of MSCs in clinical studies. Since then, studies have analyzed and identified the important signals or components in MSCs that regulate immune cells, such as macrophages, under cirrhotic conditions and have revealed that MSC-derived exosomes are key regulators. Researchers are still seeking the best approach and filling the gap between basic and clinical studies to treat liver cirrhosis. This paper highlights the timeline of basic and clinical studies analyzing ABMi and MSC therapies for cirrhosis and the scope for future studies and therapy.

Advances in mesenchymal stem cell therapy for immune and inflammatory diseases: Use of cell-free products and human pluripotent stem cell-derived mesenchymal stem cells

Mesenchymal stem cell therapy (MSCT) for immune and inflammatory diseases continues to be popular based on progressive accumulation of preclinical mechanistic evidence. This has led to further expansion in clinical indications from graft rejection, autoimmune diseases, and osteoarthritis, to inflammatory liver and pulmonary diseases including COVID‐19. A clear trend is the shift from using autologous to allogeneic MSCs, which can be immediately available as off‐the‐shelf products. In addition, new products such as cell‐free exosomes and human pluripotent stem cell (hPSC)‐derived MSCs are exciting developments to further prevalent use. Increasing numbers of trials have now published results in which safety of MSCT has been largely demonstrated. While reports of therapeutic endpoints are still emerging, efficacy can be seen for specific indications—including graft‐vs‐host‐disease, strongly Th17‐mediated autoimmune diseases, and osteoarthritis—which are more robustly supported by mechanistic preclinical evidence. In this review, we update and discuss outcomes in current MSCT clinical trials for immune and inflammatory disease, as well as new innovation and emerging trends in the field.