Immunoprivileged no more: measuring the immunogenicity of allogeneic adult mesenchymal stem cells

Nanotechnology and bioengineering approaches to improve the potency of mesenchymal stem cell as an off-the-shelf versatile tumor delivery vehicle

Targeting actionable mutations in oncogene-driven cancers and the evolution of immuno-oncology are the two prominent revolutions that have influenced cancer treatment paradigms and caused the emergence of precision oncology. However, intertumoral and intratumoral heterogeneity are the main challenges in both fields of precision cancer treatment. In other words, finding a universal marker or pathway in patients suffering from a particular type of cancer is challenging. Therefore, targeting a single hallmark or pathway with a single targeted therapeutic will not be efficient for fighting against tumor heterogeneity. Mesenchymal stem cells (MSCs) possess favorable characteristics for cellular therapy, including their hypoimmune nature, inherent tumor-tropism property, straightforward isolation, and multilineage differentiation potential. MSCs can be loaded with various chemotherapeutics and oncolytic viruses. The combination of these intrinsic features with the possibility of genetic manipulation makes them a versatile tumor delivery vehicle that can be used for in vivo selective tumor delivery of various chemotherapeutic and biological therapeutics. MSCs can be used as biofactory for the local production of chemical or biological anticancer agents at the tumor site. MSC-mediated immunotherapy could facilitate the sustained release of immunotherapeutic agents specifically at the tumor site, and allow for the achievement of therapeutic concentrations without the need for repetitive systemic administration of high therapeutic doses. Despite the enthusiasm evoked by preclinical studies that used MSC in various cancer therapy approaches, the translation of MSCs into clinical applications has faced serious challenges. This manuscript, with a critical viewpoint, reviewed the preclinical and clinical studies that have evaluated MSCs as a selective tumor delivery tool in various cancer therapy approaches, including gene therapy, immunotherapy, and chemotherapy. Then, the novel nanotechnology and bioengineering approaches that can improve the potency of MSC for tumor targeting and overcoming challenges related to their low localization at the tumor sites are discussed.

Effects of mesenchymal stem cell on dopaminergic neurons, motor and memory functions in animal models of Parkinson's disease: a systematic review and meta-analysis

ABSTRACT

Parkinson's disease is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, and although restoring striatal dopamine levels may improve symptoms, no treatment can cure or reverse the disease itself. Stem cell therapy has a regenerative effect and is being actively studied as a candidate for the treatment of Parkinson's disease. Mesenchymal stem cells are considered a promising option due to fewer ethical concerns, a lower risk of immune rejection, and a lower risk of teratogenicity. We performed a meta-analysis to evaluate the therapeutic effects of mesenchymal stem cells and their derivatives on motor function, memory, and preservation of dopaminergic neurons in a Parkinson's disease animal model. We searched bibliographic databases (PubMed/MEDLINE, Embase, CENTRAL, Scopus, and Web of Science) to identify articles and included only peer-reviewed in vivo interventional animal studies published in any language through June 28, 2023. The study utilized the random-effect model to estimate the 95% confidence intervals (CI) of the standard mean differences (SMD) between the treatment and control groups. We use the systematic review center for laboratory animal experimentation's risk of bias tool and the collaborative approach to meta-analysis and review of animal studies checklist for study quality assessment. A total of 33 studies with data from 840 Parkinson's disease model animals were included in the meta-analysis. Treatment with mesenchymal stem cells significantly improved motor function as assessed by the amphetamine-induced rotational test. Among the stem cell types, the bone marrow MSCs with neurotrophic factor group showed largest effect size (SMD [95% CI] = -6.21 [-9.50 to -2.93], P = 0.0001, I2 = 0.0 %). The stem cell treatment group had significantly more tyrosine hydroxylase positive dopaminergic neurons in the striatum ([95% CI] = 1.04 [0.59 to 1.49], P = 0.0001, I2 = 65.1 %) and substantia nigra (SMD [95% CI] = 1.38 [0.89 to 1.87], P = 0.0001, I2 = 75.3 %), indicating a protective effect on dopaminergic neurons. Subgroup analysis of the amphetamine-induced rotation test showed a significant reduction only in the intracranial-striatum route (SMD [95% CI] = -2.59 [-3.25 to -1.94], P = 0.0001, I2 = 74.4 %). The memory test showed significant improvement only in the intravenous route (SMD [95% CI] = 4.80 [1.84 to 7.76], P = 0.027, I2 = 79.6 %). Mesenchymal stem cells have been shown to positively impact motor function and memory function and protect dopaminergic neurons in preclinical models of Parkinson's disease. Further research is required to determine the optimal stem cell types, modifications, transplanted cell numbers, and delivery methods for these protocols.

Potential biomarkers for immune monitoring after renal transplantation

Renal transplantation represents the foremost efficacious approach for ameliorating end-stage renal disease. Despite the current state of advanced renal transplantation techniques and the established postoperative immunosuppression strategy, a subset of patients continues to experience immune rejection during both the early and late postoperative phases, ultimately leading to graft loss. Consequently, the identification of immunobiomarkers capable of predicting the onset of immune rejection becomes imperative in order to facilitate early intervention strategies and enhance long-term prognoses. Upon reviewing the pertinent literature, we identified several indicators that could potentially serve as immune biomarkers to varying extents. These include the T1/T2 ratio, Treg/Th17 ratio, IL-10/TNF-α ratio, IL-33, IL-34, IL-6, IL-4, other cytokines, and NOX2/4.

Mesenchymal Stem/Stromal Cell Therapy for Radiation-Induced Xerostomia in Previous Head and Neck Cancer Patients: A Phase II Randomized, Placebo-Controlled Trial

PURPOSE

No effective treatment exists for radiation-induced xerostomia. The objective of this study was to compare the effect of adipose-derived mesenchymal stem/stromal cell (ASC) injection, relative to placebo, on salivary gland function in patients with radiation-induced xerostomia.

PATIENT AND METHODS

In this single-centre, double-blind, placebo-controlled trial, patients with hyposalivation were randomised to receive ultrasound-guided injections of allogeneic ASCs or placebo into the submandibular glands. Patients were followed for 4 months. We evaluated unstimulated whole salivary flow rate (UWS), stimulated salivary flow rate, and patient-reported outcomes. Adverse events were recorded and immune response determined in blood samples.

RESULTS

We enrolled 120 patients. ASC treatment resulted in a statistically significant UWS increase of 0.04 [95% confidence interval (CI), 0.02-0.06] mL/min (38%) compared with pretreatment baseline whereas placebo treatment did not cause a significant increase [0.01 (95% CI, -0.01 to 0.04) mL/min (21%)]. Both the ASC and placebo treatment yielded notable symptom reductions, with dry mouth decreasing by 13.6 and 7.7 units, sticky saliva decreased by 14.8 and 9.3 units, swallowing difficulties decreased by 7.9 and 8.0 units, and the summary score of the Xerostomia Questionnaire decreased 5.9 and 5.1 units for the ASC and placebo arms, respectively. We found no statistically significant group difference between the ASC and placebo arms for any of the outcomes.

CONCLUSIONS

We could not confirm superiority of the ASC relative to placebo. ASC therapy significantly improved UWS in previous patients with head and neck cancer, whereas placebo resulted in an insignificant increase.

Kupffer cells abrogate homing and repopulation of allogeneic hepatic progenitors in injured liver site

BACKGROUND

Allogeneic hepatocyte transplantation is an emerging approach to treat acute liver defects. However, durable engraftment of the transplanted cells remains a daunting task, as they are actively cleared by the recipient's immune system. Therefore, a detailed understanding of the innate or adaptive immune cells-derived responses against allogeneic transplanted hepatic cells is the key to rationalize cell-based therapies.

METHODS

Here, we induced an acute inflammatory regenerative niche (3-96 h) on the surface of the liver by the application of cryo-injury (CI) to systematically evaluate the innate immune response against transplanted allogeneic hepatic progenitors in a sustained micro-inflammatory environment.

RESULTS

The resulting data highlighted that the injured site was significantly repopulated by alternating numbers of innate immune cells, including neutrophils, monocytes and Kupffer cells (KCs), from 3 to 96 h. The transplanted allo-HPs, engrafted 6 h post-injury, were collectively eliminated by the innate immune response within 24 h of transplantation. Selective depletion of the KCs demonstrated a delayed recruitment of monocytes from day 2 to day 6. In addition, the intrasplenic engraftment of the hepatic progenitors 54 h post-transplantation was dismantled by KCs, while a time-dependent better survival and translocation of the transplanted cells into the injured site could be observed in samples devoid of KCs.

CONCLUSION

Overall, this study provides evidence that KCs ablation enables a better survival and integration of allo-HPs in a sustained liver inflammatory environment, having implications for rationalizing the cell-based therapeutic interventions against liver defects.

The immunogenic profile and immunomodulatory function of mesenchymal stromal / stem cells in the presence of Ptychotis verticillata

Mesenchymal stromal/stem cells (MSCs) are considered to be a promising immunotherapeutic tool due to their easy accessibility, culture expansion possibilities, safety profile, and immunomodulatory properties. Although several studies have demonstrated the therapeutic effects of MSCs, their efficacy needs to be improved while also preserving their safety. It has been suggested that cell homeostasis may be particularly sensitive to plant extracts. The impact of natural compounds on immunity is thus a fascinating and growing field. Ptychotis verticillata and its bioactive molecules, carvacrol and thymol, are potential candidates for improving MSC therapeutic effects. They can be used as immunotherapeutic agents to regulate MSC functions and behavior during immunomodulation. Depending on their concentrations and incubation time, these compounds strengthened the immunomodulatory functions of MSCs while maintaining their immune-evasive profile. Incubating MSCs with carvacrol and thymol does not alter their hypoimmunogenicity, as no induction of the allogeneic immune response was observed. MSCs also showed enhanced abilities to reduce the proliferation of activated T cells. Thus, MSCs are immunologically responsive to bioactive molecules derived from PV. The bioactivity may depend on the whole phyto-complex of the oil. These findings may contribute to the development of safe and efficient immunotherapeutic MSCs by using medicinal plant-derived active molecules.

Enhancing Immunomodulatory Function of Mesenchymal Stromal Cells by Hydrogel Encapsulation

Mesenchymal stromal cells (MSCs) showcase remarkable immunoregulatory capabilities in vitro, positioning them as promising candidates for cellular therapeutics. However, the process of administering MSCs and the dynamic in vivo environment may impact the cell-cell and cell-matrix interactions of MSCs, consequently influencing their survival, engraftment, and their immunomodulatory efficacy. Addressing these concerns, hydrogel encapsulation emerges as a promising solution to enhance the therapeutic effectiveness of MSCs in vivo. Hydrogel, a highly flexible crosslinked hydrophilic polymer with a substantial water content, serves as a versatile platform for MSC encapsulation. Demonstrating improved engraftment and heightened immunomodulatory functions in vivo, MSCs encapsulated by hydrogel are at the forefront of advancing therapeutic outcomes. This review delves into current advancements in the field, with a focus on tuning various hydrogel parameters to elucidate mechanistic insights and elevate functional outcomes. Explored parameters encompass hydrogel composition, involving monomer type, functional modification, and co-encapsulation, along with biomechanical and physical properties like stiffness, viscoelasticity, topology, and porosity. The impact of these parameters on MSC behaviors and immunomodulatory functions is examined. Additionally, we discuss potential future research directions, aiming to kindle sustained interest in the exploration of hydrogel-encapsulated MSCs in the realm of immunomodulation.

Use of Stem Cells for the Treatment of Musculoskeletal Injuries in Horses

Mesenchymal stem cells (MSCs) are used as a regenerative therapy in horses for musculoskeletal injury since the late 1990s and in some regions are standard of care for certain injuries. Yet, there is no Food and Drug Administration-approved MSC therapeutic in the United States for horses. In humans, lack of regulatory approval in the United States has been caused by failure of late-phase clinical trials to demonstrate consistent efficacy, perhaps because of nonuniformity of MSC preparation and application techniques. This article discusses clinical evidence for musculoskeletal applications of MSCs in the horse and current challenges to marketing approval.

Overview of Equine Stem Cells: Sources, Practices, and Potential Safety Concerns

Over the past 2 decades, equine veterinarians are turning increasingly to stem cell therapies to repair damaged tissues or to promote healing through modulation of the immune system. Research is ongoing into optimizing practices associated with stem cell product transport, dosage, and administration. Culture-expanded equine mesenchymal stem cell therapies seem safe, even when used allogeneically, but various safety concerns should be considered. Stem cells and cellular reprogramming tools hold great promise for future equine therapies.

Mesenchymal Stem Cells in the Pathogenesis and Therapy of Autoimmune and Autoinflammatory Diseases

Mesenchymal stem cells (MSCs) modulate immune responses and maintain self-tolerance. Their trophic activities and regenerative properties make them potential immunosuppressants for treating autoimmune and autoinflammatory diseases. MSCs are drawn to sites of injury and inflammation where they can both reduce inflammation and contribute to tissue regeneration. An increased understanding of the role of MSCs in the development and progression of autoimmune disorders has revealed that MSCs are passive targets in the inflammatory process, becoming impaired by it and exhibiting loss of immunomodulatory activity. MSCs have been considered as potential novel cell therapies for severe autoimmune and autoinflammatory diseases, which at present have only disease modifying rather than curative treatment options. MSCs are emerging as potential therapies for severe autoimmune and autoinflammatory diseases. Clinical application of MSCs in rare cases of severe disease in which other existing treatment modalities have failed, have demonstrated potential use in treating multiple diseases, including rheumatoid arthritis, systemic lupus erythematosus, myocardial infarction, liver cirrhosis, spinal cord injury, multiple sclerosis, and COVID-19 pneumonia. This review explores the biological mechanisms behind the role of MSCs in autoimmune and autoinflammatory diseases. It also covers their immunomodulatory capabilities, potential therapeutic applications, and the challenges and risks associated with MSC therapy.

Immune Privileges as a Result of Mutual Regulation of Immune and Stem Systems

Immune privileges of cancer stem cells is a well-known and widely studied problem, as presence of such cells in tumors is associated with refractoriness, recurrence, and metastasis. Accumulating evidence also suggests presence of immune privileges in non-pathological stem cells in addition to their other defense mechanisms against damaging factors. This similarity between pathological and normal stem cells raises the question of why stem cells have such a potentially dangerous property. Regulation of vital processes of autoimmunity control and regeneration realized through interactions between immune cells, stem cells, and their microenvironment are reviewed in this work as causes of formation of the stem cell immune privilege. Deep mutual integration between regulations of stem and immune cells is noted. Considering diversity and complexity of mutual regulation of stem cells, their microenvironment, and immune system, I suggest the term "stem system".

Novel Therapeutic Opportunities for Neurodegenerative Diseases with Mesenchymal Stem Cells: The Focus on Modulating the Blood-Brain Barrier

Neurodegenerative disorders encompass a broad spectrum of profoundly disabling situations that impact millions of individuals globally. While their underlying causes and pathophysiology display considerable diversity and remain incompletely understood, a mounting body of evidence indicates that the disruption of blood-brain barrier (BBB) permeability, resulting in brain damage and neuroinflammation, is a common feature among them. Consequently, targeting the BBB has emerged as an innovative therapeutic strategy for addressing neurological disorders. Within this review, we not only explore the neuroprotective, neurotrophic, and immunomodulatory benefits of mesenchymal stem cells (MSCs) in combating neurodegeneration but also delve into their recent role in modulating the BBB. We will investigate the cellular and molecular mechanisms through which MSC treatment impacts primary age-related neurological conditions like Alzheimer's disease, Parkinson's disease, and stroke, as well as immune-mediated diseases such as multiple sclerosis. Our focus will center on how MSCs participate in the modulation of cell transporters, matrix remodeling, stabilization of cell-junction components, and restoration of BBB network integrity in these pathological contexts.

Cell-based therapies for glioblastoma: Promising tools against tumor heterogeneity

Glioblastoma (GBM) is a highly aggressive tumor with a devastating impact on quality-of-life and abysmal survivorship. Patients have very limited effective treatment options. The successes of targeted small molecule drugs and immune checkpoint inhibitors seen in various solid tumors have not translated to GBM, despite significant advances in our understanding of its molecular, immune, and microenvironment landscapes. These discoveries, however, have unveiled GBM's incredible heterogeneity and its role in treatment failure and survival. Novel cellular therapy technologies are finding successes in oncology and harbor characteristics that make them uniquely suited to overcome challenges posed by GBM, such as increased resistance to tumor heterogeneity, modularity, localized delivery, and safety. Considering these advantages, we compiled this review article on cellular therapies for GBM, focusing on cellular immunotherapies and stem cell-based therapies, to evaluate their utility. We categorize them based on their specificity, review their preclinical and clinical data, and extract valuable insights to help guide future cellular therapy development.

Potential and Limitations of Induced Pluripotent Stem Cells-Derived Mesenchymal Stem Cells in Musculoskeletal Disorders Treatment

The burden of musculoskeletal disorders (MSK) is increasing worldwide. It affects millions of people worldwide, decreases their quality of life, and can cause mortality. The treatment of such conditions is challenging and often requires surgery. Thus, it is necessary to discuss new strategies. The therapeutic potential of mesenchymal stem cells (MSC) in several diseases has been investigated with relative success. However, this potential is hindered by their limited stemness and expansion ability in vitro and their high donor variability. MSC derived from induced pluripotent stem cells (iPSC) have emerged as an alternative treatment for MSK diseases. These cells present distinct features, such as a juvenile phenotype, in addition to higher stemness, proliferation, and differentiation potential than those of MSC. Here, we review the opportunities, challenges, and applications of iPSC as relevant clinical therapeutic cell sources for MSK disorders. We discuss iPSC sources from which to derive iMSC and the advantages and disadvantages of iMSC over MSC as a therapeutic approach. We further summarize the main preclinical and clinical studies exploring the therapeutic potential of iMSC in MSK disorders.

Exosomes derived from mesenchymal stromal cells promote bone regeneration by delivering miR-182-5p-inhibitor

Exosomes, small extracellular vesicles that function as a key regulator of cell-to-cell communication, are emerging as a promising candidate for bone regeneration. Here, we aimed to investigate the effect of exosomes from pre-differentiated human alveolar bone-derived bone marrow mesenchymal stromal cells (AB-BMSCs) carrying specific microRNAs on bone regeneration. Exosomes secreted from AB-BMSCs pre-differentiated for 0 and 7 days were cocultured with BMSCs in vitro to investigate their effect on the differentiation of the BMSCs. MiRNAs from AB-BMSCs at different stages of osteogenic differentiation were analyzed. BMSCs seeded on poly-L-lactic acid(PLLA) scaffolds were treated with miRNA antagonist-decorated exosomes to verify their effect on new bone regeneration. Exosomes pre-differentiated for 7 days effectively promoted the differentiation of BMSCs. Bioinformatic analysis revealed that miRNAs within the exosomes were differentially expressed, including the upregulation of osteogenic miRNAs (miR-3182, miR-1468) and downregulation of anti-osteogenic miRNAs (miR-182-5p, miR-335-3p, miR-382-5p), causing activation of the PI3K/Akt signaling pathway. The treatment of BMSC-seeded scaffolds with anti-miR-182-5p decorated exosomes demonstrated enhanced osteogenic differentiation and efficient formation of new bone. In conclusion, Osteogenic exosomes secreted from pre-differentiated AB-BMSCs were identified and the gene modification of exosomes provides great potential as a bone regeneration strategy. DATA AVAILABILITY STATEMENT: Data generated or analyzed in this paper partly are available in the GEO public data repository(http://www.ncbi.nlm.nih.gov/geo).

Local, systemic and immunologic safety comparison between xenogeneic equine umbilical cord mesenchymal stem cells, allogeneic canine adipose mesenchymal stem cells and placebo: a randomized controlled trial

Mesenchymal stem cells are multipotent cells with a wide range of therapeutic applications, including, among others, tissue regeneration. This work aims to test the safety (EUC-MSC) of intra-articular administration of equine umbilical cord mesenchymal stem cells in young healthy dogs under field conditions following single and repeated administration. This was compared with the safety profile of allogenic canine adipose derived mesenchymal stem cells (CAD-MSC) and placebo in order to define the safety of xenogeneic use of mesenchymal stem cells when administered intra-articular. Twenty-four police working dogs were randomized in three groups in a proportion 1:1:1. EUC-MSCs and CAD-MSCs were obtained from healthy donors and were manufactured following company SOPs and under GMP and GMP-like conditions, respectively, and compliant all necessary controls to ensure the quality of the treatment. The safety of the treatment was evaluated locally, systemically and immunologically. For this purpose, an orthopedic examination and Glasgow test for the assessment of pain in the infiltrated joint, blood tests, clinical examination and analysis of the humoral and cellular response to treatment were performed. No adverse events were detected following single and repeated MSC administration despite both equine and canine MSC generate antibody titres in the dogs. The intra-articular administration of equine umbilical cord mesenchymal stem cells in dogs has demonstrated to be safe.

Current perspectives on mesenchymal stromal cell therapy for graft versus host disease

Graft versus host disease (GvHD) is the clinical condition in which bone marrow-derived mesenchymal stromal cells (MSCs) have been most frequently studied. In this review, we summarize the experience from clinical trials that have paved the way to translation. While MSC-based therapy has shown an exceptional safety profile, identifying potency assays and disease biomarkers that reliably predict the capacity of a specific MSC batch to alleviate GvHD has been difficult. As GvHD diagnosis and staging are based solely on clinical criteria, individual patients recruited in the same clinical trial may have vastly different underlying biology, obscuring trial outcomes and making it difficult to determine the benefit of MSCs in subgroups of patients. An accumulating body of evidence indicates the importance of considering not only the cell product but also patient-specific biomarkers and/or immune characteristics in determining MSC responsiveness. A mode of action where intravascular MSC destruction is followed by monocyte-efferocytosis-mediated skewing of the immune repertoire in a permissive inflammatory environment would both explain why cell engraftment is irrelevant for MSC efficacy and stress the importance of biologic differences between responding and nonresponding patients. We recommend a combined analysis of clinical outcomes and both biomarkers of disease activity and MSC potency assays to identify patients with GvHD who are likely to benefit from MSC therapy.

Serum- and xeno-free culture of human umbilical cord perivascular cells for pediatric heart valve tissue engineering

BACKGROUND

Constructs currently used to repair or replace congenitally diseased pediatric heart valves lack a viable cell population capable of functional adaptation in situ, necessitating repeated surgical intervention. Heart valve tissue engineering (HVTE) can address these limitations by producing functional living tissue in vitro that holds the potential for somatic growth and remodelling upon implantation. However, clinical translation of HVTE strategies requires an appropriate source of autologous cells that can be non-invasively harvested from mesenchymal stem cell (MSC)-rich tissues and cultured under serum- and xeno-free conditions. To this end, we evaluated human umbilical cord perivascular cells (hUCPVCs) as a promising cell source for in vitro production of engineered heart valve tissue.

METHODS

The proliferative, clonogenic, multilineage differentiation, and extracellular matrix (ECM) synthesis capacities of hUCPVCs were evaluated in a commercial serum- and xeno-free culture medium (StemMACS™) on tissue culture polystyrene and benchmarked to adult bone marrow-derived MSCs (BMMSCs). Additionally, the ECM synthesis potential of hUCPVCs was evaluated when cultured on polycarbonate polyurethane anisotropic electrospun scaffolds, a representative biomaterial for in vitro HVTE.

RESULTS

hUCPVCs had greater proliferative and clonogenic potential than BMMSCs in StemMACS™ (p < 0.05), without differentiation to osteogenic and adipogenic phenotypes associated with valve pathology. Furthermore, hUCPVCs cultured with StemMACS™ on tissue culture plastic for 14 days synthesized significantly more total collagen, elastin, and sulphated glycosaminoglycans (p < 0.05), the ECM constituents of the native valve, than BMMSCs. Finally, hUCPVCs retained their ECM synthesizing capacity after 14 and 21 days in culture on anisotropic electrospun scaffolds.

CONCLUSION

Overall, our findings establish an in vitro culture platform that uses hUCPVCs as a readily-available and non-invasively sourced autologous cell population and a commercial serum- and xeno-free culture medium to increase the translational potential of future pediatric HVTE strategies. This study evaluated the proliferative, differentiation and extracellular matrix (ECM) synthesis capacities of human umbilical cord perivascular cells (hUCPVCs) when cultured in serum- and xeno-free media (SFM) against conventionally used bone marrow-derived MSCs (BMMSCs) and serum-containing media (SCM). Our findings support the use of hUCPVCs and SFM for in vitro heart valve tissue engineering (HVTE) of autologous pediatric valve tissue. Figure created with BioRender.com.

Mesenchymal Stromal Cells-Derived Exosome and the Roles in the Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) could result in life-long disabilities and death. Though the mechanical insult causes primary injury, the secondary injury due to dysregulated responses following neuronal apoptosis and inflammation is often the cause for more detrimental consequences. Mesenchymal stromal cell (MSC) has been extensively investigated as the emerging therapeutic for TBI, and the functional properties are chiefly attributed to their secretome, especially the exosomes. Delivering these nanosize exosomes have shown to ameliorate post-traumatic injury and restore brain functions. Recent technology advances also allow engineering MSC-derived exosomes to carry specific biomolecules of interest to augment their therapeutic outcome. In this review, we discuss the pathophysiology of TBI and summarize the recent progress in the applications of MSCs-derived exosomes, the roles and the signalling mechanisms underlying the protective effects in the treatment of the TBI.

Therapeutic potential of extracellular vesicles in neurodegenerative disorders

Neurodegenerative disorders are characterized by complex multifactorial pathogeneses, thus posing a challenge for standard therapeutic approaches that tend to focus only on one underlying disease aspect. For systemically administered drugs, the blood-brain barrier (BBB) is yet another major obstacle to overcome. In this context, naturally occurring extracellular vesicles (EVs) with intrinsic ability to cross the BBB have been investigated as therapeutics for various diseases, including Alzheimer's and Parkinson's diseases. EVs are cell-derived, lipid membrane-enclosed vesicles carrying a broad spectrum of biologically active molecules, which play a crucial role in intercellular communication. In a therapeutic context, mesenchymal stem cell (MSC)-derived EVs are in the spotlight because they reflect the therapeutic properties of their parental cells and, thus, hold promise as independent cell-free therapeutics. On the other hand, EVs can be used as drug delivery vehicles by modifying their surface or content, e.g., by decorating the surface with brain-specific ligands or loading the EVs with therapeutic RNAs or proteins, thus further enhancing the EV's targeting and therapeutic potency, respectively. Although EVs have been deemed safe for use in humans, some obstacles remain that prevent their progression into clinics. This review scrutinizes the promises and challenges of EV-based treatments for neurodegenerative disorders.

Autologous Human Mesenchymal Stem Cell-Based Therapy in Infertility: New Strategies and Future Perspectives

Infertility could be associated with a few factors including problems with physical and mental health, hormonal imbalances, lifestyles, and genetic factors. Given that there is a concern about the rise of infertility globally, increased focus has been given to its treatment for the last several decades. Traditional assisted reproductive technology (ART) has been the prime option for many years in solving various cases of infertility; however, it contains significant risks and does not solve the fundamental problem of infertility such as genetic disorders. Attention toward the utilization of MSCs has been widely regarded as a promising option in the development of stem-cell-based infertility treatments. This narrative review briefly presents the challenges in the current ART treatment of infertility and the various potential applications of autologous MSCs in the treatment of these reproductive diseases.

The Safety and Efficacy of Mesenchymal Stem Cells in the Treatment of Type 2 Diabetes- A Literature Review

INTRODUCTION

Type 2 diabetes (T2D) is the most common type of diabetes, affecting 6.28% of the population worldwide. Over the decades, multiple therapies and drugs have been developed to control T2D, but they are far from a long-term solution. Stem cells are promising as novel regenerative treatments, especially mesenchymal stem cells (MSCs), which are highly versatile in their regenerative and paracrine capabilities and characteristics. This makes them the most commonly used adult stem cells and ideal candidates to treat diabetes.

OBJECTIVE

To assess the safety and efficacy of mesenchymal stem cells (MSCs) in treating Type 2 diabetes (T2D) in humans.

METHODS

Mesenchymal stem cell-based treatments were studied in 262 patients. A total of 6 out of 58 trials fit our inclusion criteria in the last five years.

RESULTS

The treatment of patients with MSCs reduced the dosage of anti-diabetic drugs analyzed over a follow-up period of 12 months. The effective therapy dosage ranged from 1×10⁶ cells/kg to 3.7×10⁶ cells/kg. After treatment, HbAc1 levels were reduced by an average of 32%, and the fasting blood glucose levels were reduced to an average of 45%. The C-peptide levels were decreased by an average of 38% in 2 trials and increased by 36% in 4 trials. No severe adverse events were noted in all trials.

CONCLUSION

This analysis concludes that MSC treatment of type 2 diabetes is safe and effective. A larger sample size is required, and the trials should also study the effect of differentiated MSCs as insulin-producing cells.

Umbilical cord mesenchymal stromal cells transplantation delays the onset of hyperglycemia in the RIP-B7.1 mouse model of experimental autoimmune diabetes through multiple immunosuppressive and anti-inflammatory responses

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder specifically targeting pancreatic islet beta cells. Despite many efforts focused on identifying new therapies able to counteract this autoimmune attack and/or stimulate beta cells regeneration, TD1M remains without effective clinical treatments providing no clear advantages over the conventional treatment with insulin. We previously postulated that both the inflammatory and immune responses and beta cell survival/regeneration must be simultaneously targeted to blunt the progression of disease. Umbilical cord-derived mesenchymal stromal cells (UC-MSC) exhibit anti-inflammatory, trophic, immunomodulatory and regenerative properties and have shown some beneficial yet controversial effects in clinical trials for T1DM. In order to clarify conflicting results, we herein dissected the cellular and molecular events derived from UC-MSC intraperitoneal administration (i.p.) in the RIP-B7.1 mouse model of experimental autoimmune diabetes. Intraperitoneal (i.p.) transplantation of heterologous mouse UC-MSC delayed the onset of diabetes in RIP-B7.1 mice. Importantly, UC-MSC i. p. transplantation led to a strong peritoneal recruitment of myeloid-derived suppressor cells (MDSC) followed by multiple T-, B- and myeloid cells immunosuppressive responses in peritoneal fluid cells, spleen, pancreatic lymph nodes and the pancreas, which displayed significantly reduced insulitis and pancreatic infiltration of T and B Cells and pro-inflammatory macrophages. Altogether, these results suggest that UC-MSC i. p. transplantation can block or delay the development of hyperglycemia through suppression of inflammation and the immune attack.

Skin-Derived ABCB5+ Mesenchymal Stem Cells for High-Medical-Need Inflammatory Diseases: From Discovery to Entering Clinical Routine

The ATP-binding cassette superfamily member ABCB5 identifies a subset of skin-resident mesenchymal stem cells (MSCs) that exhibit potent immunomodulatory and wound healing-promoting capacities along with superior homing ability. The ABCB5+ MSCs can be easily accessed from discarded skin samples, expanded, and delivered as a highly homogenous medicinal product with standardized potency. A range of preclinical studies has suggested therapeutic efficacy of ABCB5+ MSCs in a variety of currently uncurable skin and non-skin inflammatory diseases, which has been substantiated thus far by distinct clinical trials in chronic skin wounds or recessive dystrophic epidermolysis bullosa. Therefore, skin-derived ABCB5+ MSCs have the potential to provide a breakthrough at the forefront of MSC-based therapies striving to fulfill current unmet medical needs. The most recent milestones in this regard are the approval of a phase III pivotal trial of ABCB5+ MSCs for treatment of recessive dystrophic and junctional epidermolysis bullosa by the US Food and Drug Administration, and national market access of ABCB5+ MSCs (AMESANAR®) for therapy-refractory chronic venous ulcers under the national hospital exemption pathway in Germany.

Extracellular Hemoglobin: Modulation of Cellular Functions and Pathophysiological Effects

Hemoglobin is essential for maintaining cellular bioenergetic homeostasis through its ability to bind and transport oxygen to the tissues. Besides its ability to transport oxygen, hemoglobin within erythrocytes plays an important role in cellular signaling and modulation of the inflammatory response either directly by binding gas molecules (NO, CO, and CO2) or indirectly by acting as their source. Once hemoglobin reaches the extracellular environment, it acquires several secondary functions affecting surrounding cells and tissues. By modulating the cell functions, this macromolecule becomes involved in the etiology and pathophysiology of various diseases. The up-to-date results disclose the impact of extracellular hemoglobin on (i) redox status, (ii) inflammatory state of cells, (iii) proliferation and chemotaxis, (iv) mitochondrial dynamic, (v) chemoresistance and (vi) differentiation. This review pays special attention to applied biomedical research and the use of non-vertebrate and vertebrate extracellular hemoglobin as a promising candidate for hemoglobin-based oxygen carriers, as well as cell culture medium additive. Although recent experimental settings have some limitations, they provide additional insight into the modulatory activity of extracellular hemoglobin in various cellular microenvironments, such as stem or tumor cells niches.

The immunomodulation-immunogenicity balance of equine Mesenchymal Stem Cells (MSCs) is differentially affected by the immune cell response depending on inflammatory licensing and major histocompatibility complex (MHC) compatibility

The immunomodulatory properties of equine mesenchymal stem cells (MSCs) are important for their therapeutic potential and for their facilitating role in their escape from immune recognition, which may also be influenced by donor-recipient major histocompatibility complex (MHC) matching/mismatching and MHC expression level. Factors such as inflammation can modify the balance between regulatory and immunogenic profiles of equine MSCs, but little is known about how the exposure to the immune system can affect these properties in equine MSCs. In this study, we analyzed the gene expression and secretion of molecules related to the immunomodulation and immunogenicity of equine MSCs, either non-manipulated (MSC-naive) or stimulated by pro-inflammatory cytokines (MSC-primed), before and after their exposure to autologous or allogeneic MHC-matched/-mismatched lymphocytes, either activated or resting. Cytokine priming induced the immunomodulatory profile of MSCs at the baseline (MSCs cultured alone), and the exposure to activated lymphocytes further increased the expression of interleukin 6 (IL6), cyclooxygenase 2, and inducible nitric oxide synthase, and IL6 secretion. Activated lymphocytes were also able to upregulate the regulatory profile of MSC-naive to levels comparable to cytokine priming. On the contrary, resting lymphocytes did not upregulate the immunomodulatory profile of equine MSCs, but interestingly, MSC-primed exposed to MHC-mismatched lymphocytes showed the highest expression and secretion of these mediators, which may be potentially linked to the activation of lymphocytes upon recognition of foreign MHC molecules. Cytokine priming alone did not upregulate the immunogenic genes, but MSC-primed exposed to activated or resting lymphocytes increased their MHC-I and MHC-II expression, regardless of the MHC-compatibility. The upregulation of immunogenic markers including CD40 in the MHC-mismatched co-culture might have activated lymphocytes, which, at the same time, could have promoted the immune regulatory profile aforementioned. In conclusion, activated lymphocytes are able to induce the equine MSC regulatory profile, and their effects seem to be additive to the priming action. Importantly, our results suggest that the lymphocyte response against MHC-mismatched MSC-primed would promote further activation of their immunomodulatory ability, which eventually might help them evade this reaction. Further studies are needed to clarify how these findings might have clinical implications in vivo, which will help developing safer and more effective therapies.

TGF-β2 enhances expression of equine bone marrow-derived mesenchymal stem cell paracrine factors with known associations to tendon healing

Background

Mesenchymal stem cells (MSCs) secrete paracrine factors and extracellular matrix proteins that contribute to their ability to support tissue healing and regeneration. Both the transcriptome and the secretome of MSCs can be altered by treating the cells with cytokines, but neither have been thoroughly investigated following treatment with the specific cytokine transforming growth factor (TGF)-β2.

Methods

RNA-sequencing and western blotting were used to compare gene and protein expression between untreated and TGF-β2-treated equine bone marrow-derived MSCs (BM-MSCs). A co-culture system was utilized to compare equine tenocyte migration during co-culture with untreated and TGF-β2-treated BM-MSCs.

Results

TGF-β2 treatment significantly upregulated gene expression of collagens, extracellular matrix molecules, and growth factors. Protein expression of collagen type I and tenascin-C was also confirmed to be upregulated in TGF-β2-treated BM-MSCs compared to untreated BM-MSCs. Both untreated and TGF-β2-treated BM-MSCs increased tenocyte migration in vitro.

Conclusions

Treating equine BM-MSCs with TGF-β2 significantly increases production of paracrine factors and extracellular matrix molecules important for tendon healing and promotes the migration of tenocytes in vitro.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03172-9.

Nestin-GFP transgene labels immunoprivileged bone marrow mesenchymal stem cells in the model of ectopic foci formation

Immune privileges are demonstrated for different types of quiescent stem cells of adult mammalian organisms. Mesenchymal stem cells (MSCs) are believed to have immune privileges; however, an accurate experimental confirmation hasn’t been presented. Here, we provide direct experimental evidence that MSCs of C57Black/6J murine bone marrow (BM) are immune privileged in vivo and retain their functionality after prolonged exposure to the uncompromised immune system. The BM of Nes-Gfp transgenic mice was implanted as a tissue fragment under the kidney capsule in isogenic C57Black/6J immunocompetent recipients. Nestin-Gfp strain provides a fluorescent immunogenic marker for a small fraction of BM cells, including GFP+CD45– MSCs. Despite the exposure of xenogenically marked MSCs to the fully-functional immune system, primary ectopic foci of hematopoiesis formed. Six weeks after implantation, multicolor fluorescence cytometry revealed both GFP+CD45– and GFP+CD45+ cells within the foci. GFP+CD45– cells proportion was 2.0 × 10–5 ×÷9 and it didn’t differ significantly from syngenic Nes-GFP transplantation control. According to current knowledge, the immune system of the recipients should eliminate GFP+ cells, including GFP+ MSCs. These results show that MSCs evade immunity. Primary foci were retransplanted into secondary Nes-GFP recipients. The secondary foci formed, in which CD45–GFP+ cells proportion was 6.7 × 10–5 ×÷2.2, and it didn’t differ from intact Nes-GFP BM. The results demonstrate that MSCs preserve self-renewal and retain their functionality after prolonged immune exposure. The success of this study relied on the implantation of BM fragments without prior dissociation of cells and the fact that the vast majority of implanted cells were immunologically equivalent to the recipients.

Combination of Dexamethasone and Tofacitinib Reduces Xenogeneic MSC-Induced Immune Responses in a Mouse Model of Alzheimer’s Disease

We have recently reported on how transplantation of human mesenchymal stem cells (MSCs) into the mouse parenchyma generated immune responses. To facilitate the clinical translation of MSC-based AD therapy, the safety and efficacy of human derived MSCs (hMSCs) must be confirmed in the pre-clinical stage. Thus, it is imperative to investigate measures to reduce immune responses exerted via xenotransplantation. In this study, immunosuppressants were co-administered to mice that had received injections of hMSCs into the parenchyma. Prior to performing experiments using transgenic AD mice (5xFAD), varying immunosuppressant regimens were tested in wild-type (WT) mice and the combination of dexamethasone and tofacitinib (DexaTofa) revealed to be effective in enhancing the persistence of hMSCs. According to transcriptome sequencing and immunohistochemical analyses, administration of DexaTofa reduced immune responses generated via transplantation of hMSCs in the parenchyma of 5xFAD mice. Significant mitigation of amyloid burden, however, was not noted following transplantation of hMSCs alone or hMSCs with DexaTofa. The efficacy of the immunosuppressant regimen should be tested in multiple AD mouse models to promote its successful application and use in AD stem cell therapy.

Upscaling human mesenchymal stromal cell production in a novel vertical-wheel bioreactor enhances extracellular vesicle secretion and cargo profile

Human mesenchymal stromal cells (hMSCs) are mechanically sensitive undergoing phenotypic alterations when subjected to shear stress, cell aggregation, and substrate changes encountered in 3D dynamic bioreactor cultures. However, little is known about how bioreactor microenvironment affects the secretion and cargo profiles of hMSC-derived extracellular vesicles (EVs) including the subset, "exosomes", which contain therapeutic proteins, nucleic acids, and lipids from the parent cells. In this study, bone marrow-derived hMSCs were expanded on 3D Synthemax II microcarriers in the PBS mini 0.1L Vertical-Wheel bioreactor system under variable shear stress levels at 25, 40, and 64 RPM (0.1-0.3 dyn/cm²). The bioreactor system promotes EV secretion from hMSCs by 2.5-fold and upregulates the expression of EV biogenesis markers and glycolysis genes compared to the static 2D culture. The microRNA cargo was also altered in the EVs from bioreactor culture including the upregulation of miR-10, 19a, 19b, 21, 132, and 377. EV protein cargo was characterized by proteomics analysis, showing upregulation of metabolic, autophagy and ROS-related proteins comparing with 2D cultured EVs. In addition, the scalability of the Vertical-Wheel bioreactor system was demonstrated in a 0.5L bioreactor, showing similar or better hMSC-EV secretion and cargo content compared to the 0.1L bioreactor. This study advances our understanding of bio-manufacturing of stem cell-derived EVs for applications in cell-free therapy towards treating neurological disorders such as ischemic stroke, Alzheimer's disease, and multiple sclerosis.

Gene Therapy in Orthopaedics: Progress and Challenges in Pre-Clinical Development and Translation

In orthopaedics, gene-based treatment approaches are being investigated for an array of common -yet medically challenging- pathologic conditions of the skeletal connective tissues and structures (bone, cartilage, ligament, tendon, joints, intervertebral discs etc.). As the skeletal system protects the vital organs and provides weight-bearing structural support, the various tissues are principally composed of dense extracellular matrix (ECM), often with minimal cellularity and vasculature. Due to their functional roles, composition, and distribution throughout the body the skeletal tissues are prone to traumatic injury, and/or structural failure from chronic inflammation and matrix degradation. Due to a mixture of environment and endogenous factors repair processes are often slow and fail to restore the native quality of the ECM and its function. In other cases, large-scale lesions from severe trauma or tumor surgery, exceed the body’s healing and regenerative capacity. Although a wide range of exogenous gene products (proteins and RNAs) have the potential to enhance tissue repair/regeneration and inhibit degenerative disease their clinical use is hindered by the absence of practical methods for safe, effective delivery. Cumulatively, a large body of evidence demonstrates the capacity to transfer coding sequences for biologic agents to cells in the skeletal tissues to achieve prolonged delivery at functional levels to augment local repair or inhibit pathologic processes. With an eye toward clinical translation, we discuss the research progress in the primary injury and disease targets in orthopaedic gene therapy. Technical considerations important to the exploration and pre-clinical development are presented, with an emphasis on vector technologies and delivery strategies whose capacity to generate and sustain functional transgene expression in vivo is well-established.

Mesenchymal stem cell transplantation in newly diagnosed type-1 diabetes patients: a phase I/II randomized placebo-controlled clinical trial

Background

Type-1 diabetes (T1D) occurs following autoimmune-induced pancreatic beta cells death. Among several treatment modalities, mesenchymal stem cells (MSCs) transplantation is promising for autoimmune disorders due to immunomodulation, regeneration, and migration to damaged tissue upon systemic injection. This study assessed the safety and efficacy of intravenous injection of autologous bone marrow-derived MSCs in newly diagnosed T1D patients.

Methods

After receiving informed consent, 21 patients who met the study criteria were enrolled and randomly assigned to receive either MSCs or placebo. Each patient in the experimental group received two doses of MSCs and was followed for at least one-year post-transplantation.

Results

The results have shown that this transplantation is safe and significantly reduces the number of hypoglycemic episodes. MSCs transplantation improved glycated hemoglobin (HbA1c), shifted serum cytokine patterns from pro-inflammatory to anti-inflammatory, increased the number of regulatory T-cells in the peripheral blood, and improved quality of life. Early transplantation of MSCs significantly improved HbA1c and C-peptide levels and shifted pro-inflammatory cytokines to anti-inflammatory cytokines. Also, exercise combined with MSCs transplantation improved glycemic and immunologic indices.

Conclusions

Taken together, autologous MSC transplantation is safe and effective, and its early transplantation is a promising treatment in newly diagnosed T1D children suffering from hypoglycemic episodes.

Trial registration: This clinical trial was registered at the Iranian Registry of Clinical Trials (IRCT) with the identifier IRCT ID: IRCT2016070428786N1 registered on August 20, 2016 (Retrospectively registered) (https://en.irct.ir/trial/23256) and at the U.S. National Institutes of Health (ClinicalTrials.gov) with the related identifier NCT04078308 registered on September 6, 2019 (Retrospectively registered). (https://clinicaltrials.gov/ct2/show/NCT04078308).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02941-w.

Immunotherapy by mesenchymal stromal cell delivery of oncolytic viruses for treating metastatic tumors

Oncolytic viruses (OVs) have emerged as a very promising anti-cancer therapeutic strategy in the past decades. However, despite their pre-clinical promise, many OV clinical evaluations for cancer therapy have highlighted the continued need for their improved delivery and targeting. Mesenchymal stromal cells (MSCs) have emerged as excellent candidate vehicles for the delivery of OVs due to their tumor-homing properties and low immunogenicity. MSCs can enhance OV delivery by protecting viruses from rapid clearance following administration and also by more efficiently targeting tumor sites, consequently augmenting the therapeutic potential of OVs. MSCs can function as “biological factories,” enabling OV amplification within these cells to promote tumor lysis following MSC-OV arrival at the tumor site. MSC-OVs can promote enhanced safety profiles and therapeutic effects relative to OVs alone. In this review we explore the general characteristics of MSCs as delivery tools for cancer therapeutic agents. Furthermore, we discuss the potential of OVs as immune therapeutics and highlight some of the promising applications stemming from combining MSCs to achieve enhanced delivery and anti-tumor effectiveness of OVs at different pre-clinical and clinical stages. We further provide potential pitfalls of the MSC-OV platform and the strategies under development for enhancing the efficacy of these emerging therapeutics.

Embedding MSCs in Si-HPMC hydrogel decreased MSC-directed host immune response and increased the regenerative potential of macrophages

Embedding mesenchymal stromal cells (MSCs) in biomaterial is a subject of increasing interest in the field of Regenerative Medicine. Speeding up the clinical use of MSCs is dependent on the use of non-syngeneic models in accordance with Good Manufacturing Practices (GMP) requirements and on costs. To this end, in this study, we analyzed the in vivo host immune response following local injection of silanized hydroxypropyl methylcellulose (Si-HPMC)-embedded human MSCs in a rat model developing colorectal damage induced by ionizing radiation. Plasma and lymphocytes from mesenteric lymph nodes were harvested in addition to colonic tissue. We set up tests, using flow cytometry and a live imaging system, to highlight the response to specific antibodies and measure the cytotoxicity of lymphocytes against injected MSCs. We demonstrated that Si-HPMC protects MSCs from specific antibodies production and from apoptosis by lymphocytes. We also observed that Si-HPMC does not modify innate immune response infiltrate in vivo, and that in vitro co-culture of Si-HPMC-embedded MSCs impacts macrophage inflammatory response depending on the microenvironment but, more importantly, increases the macrophage regenerative response through Wnt-family and VEGF gene expression. This study furthers our understanding of the mechanisms involved, with a view to improving the therapeutic benefits of biomaterial-assisted cell therapy by modulating the host immune response. The decrease in specific immune response against injected MSCs protected by Si-HPMC also opens up new possibilities for allogeneic clinical use.

Labial Gland Mesenchymal Stem Cell Derived Exosomes-Mediated miRNA-125b Attenuates Experimental Sjogren's Syndrome by Targeting PRDM1 and Suppressing Plasma Cells

The pathogenesis of the prototypical chronic autoimmune disorder primary Sjögren syndrome (pSS) has been thought to be B-cell-centric, based on serum autoantibodies, the increased risk of B cell lymphoma, and altered B cell subsets in patients with pSS. Over the last 10 years, therapies targeting B cells have been investigated for pSS; however, current evidence for the efficacy of B cell targeted therapies in pSS is still sparse. Mesenchymal stem cells (MSCs) might represent a promising strategy for cell therapy of autoimmune diseases via regulation of immune cells. MSC-released exosomes carry various bioactive molecules and thus have been studied in MSC-based therapy. The newly discovered labial gland MSCs (LGMSCs) have exhibited enhanced performance. Herein, we aimed to determine the effects of LGMSC-derived exosomes (LGMSC-Exos) on the symptoms of a mouse model of pSS and their regulatory effect and mechanism on B cell subsets. In vivo, treatment of the spontaneous mouse model of pSS with LGMSC-Exos resulted in reduced inflammatory infiltration and restored saliva secretion in salivary glands. In vitro, coculture of LGMSC-Exos with peripheral blood mononuclear cells of patients with pSS markedly reduced the proportions of CD19⁺CD20^-CD27⁺CD38⁺ plasma cells among peripheral blood mononuclear cells. Further investigations provided evidence that LGMSC-Exo-derived microRNA-125b affected plasma cells of pSS by directly binding to its target gene, PRDM1 (PR domain zinc finger protein 1, also known as BLIMP1), which might be developed as a target to treat pSS. Overall, these findings provided a possible exploitable therapeutic target in pSS and provide new insights into the potential therapeutic application of exosomes in pSS and other disease mediated by B-cells.

Equine Mesenchymal Stem Cells Influence the Proliferative Response of Lymphocytes: Effect of Inflammation, Differentiation and MHC-Compatibility

Simple Summary

Mesenchymal stem cells are investigated for therapy because of their ability to regulate the immune response to an injury. Cell therapy is increasingly important in veterinary patients such as horses, which are also valuable as a model. Therefore, what is learned in these animals can benefit both them and people. However, the patient’s immune system could recognize and destroy mesenchymal stem cells, impairing effectiveness and potentially leading to adverse effects. In this study, we analysed how equine mesenchymal stem cells interact with immune cells in different scenarios. We tested the effect of inflammation and differentiation of these cells, and how they acted depending on donor–patient compatibility. As we expected, inflammation activated the regulatory ability of equine mesenchymal stem cells, but also increased the risk of immune recognition. We anticipated that, after differentiation, these cells would lose their regulatory ability and would be more easily targeted by the immune system. However, they maintained similar features after differentiating into cartilage cells. The balance between the ability of mesenchymal stem cells to stimulate and to regulate an immune response is of the utmost importance to develop safe and effective cell therapies for animals and people.

Abstract

Immunomodulation and immunogenicity are pivotal aspects for the therapeutic use of mesenchymal stem cells (MSCs). Since the horse is highly valuable as both a patient and translational model, further knowledge on equine MSC immune properties is required. This study analysed how inflammation, chondrogenic differentiation and compatibility for the major histocompatibility complex (MHC) influence the MSC immunomodulatory–immunogenicity balance. Equine MSCs in basal conditions, pro-inflammatory primed (MSC-primed) or chondrogenically differentiated (MSC-chondro) were co-cultured with either autologous or allogeneic MHC-matched/mismatched lymphocytes in immune-suppressive assays (immunomodulation) and in modified one-way mixed leukocyte reactions (immunogenicity). After co-culture, frequency and proliferation of T cell subsets and B cells were assessed by flow cytometry and interferon-ɣ (IFNɣ) secretion by ELISA. MSC-primed showed higher regulatory potential by decreasing proliferation of cytotoxic and helper T cells and B cells. However, MHC-mismatched MSC-primed can also activate lymphocytes (proliferative response and IFNɣ secretion), likely due to increased MHC-expression. MSC-chondro maintained their regulatory ability and did not increase their immunogenicity, but showed less capacity than MSC-primed to induce regulatory T cells and further stimulated B cells. Subsequent in vivo studies are needed to elucidate the complex interactions between MSCs and the recipient immune system, which is critical to develop safe and effective therapies.

Menstrual blood-derived mesenchymal stromal cells efficiently ameliorate experimental autoimmune encephalomyelitis by inhibiting T cell activation in mice

Background

Immunosuppressive properties grant mesenchymal stromal cells (MSCs) promising potential for treating autoimmune diseases. As autologous MSCs suffer from limited availability, the readily available allogeneic MSCs isolated from menstrual blood (MB-MSCs) donated by young, healthy individuals offer great potential. Here, we evaluate the therapeutic potential of MB-MSCs as ready-to-use allo-MSCs in multiple sclerosis, an autoimmune disease developed by the activation of myelin sheath-reactive Th1 and Th17 cells, by application in its animal model experimental autoimmune encephalomyelitis (EAE).

Methods

We assessed the therapeutic effect of MB-MSCs transplanted via either intravenous (i.v.) or intraperitoneal (i.p.) route in EAE in comparison with umbilical cord-derived MSCs (UC-MSCs). We used histology to assess myelin sheath integrity and infiltrated immune cells in CNS and flow cytometry to evaluate EAE-associated inflammatory T cells and antigen-presenting cells in lymphoid organs.

Results

We observed disease-ameliorating effects of MB-MSCs when transplanted at various stages of EAE (day − 1, 6, 10, and 19), via either i.v. or i.p. route, with a potency comparable to UC-MSCs. We observed reduced Th1 and Th17 cell responses in mice that had received MB-MSCs via either i.v. or i.p. injection. The repressed Th1 and Th17 cell responses were associated with a reduced frequency of plasmacytoid dendritic cells (pDCs) and a suppressed co-stimulatory capacity of pDCs, cDCs, and B cells.

Conclusions

Our data demonstrate that the readily available MB-MSCs significantly reduced the disease severity of EAE upon transplantation. Thus, they have the potential to be developed as ready-to-use allo-MSCs in MS-related inflammation.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02838-8.

Infusion of Allogeneic Mesenchymal Stromal Cells After Liver Transplantation: A 5-Year Follow-Up

Various properties of mesenchymal stromal cells (MSCs) might be particularly of interest after liver transplantation (LT). In this article, we report the long-term results of a prospective, controlled, and first-in-human phase 1 study evaluating the safety of a single MSC infusion after LT. A total of 10 LT recipients treated with standard immunosuppression received 1.5 to 3 × 10⁶ /kg third-party unrelated MSCs on postoperative day 3 and were prospectively compared with a control group of 10 LT recipients. Primary endpoints were set to prospectively detect potentially delayed adverse effects of MSC infusion, particularly the occurrence of infections and cancers. Secondary endpoints of liver graft and patient survival, graft rejection and function, occurrence of bile duct complications, and development of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSA) against liver or MSC donors were studied. The median follow-up was 85 months. There was no difference in overall rates of infection or cancer at 5 years of follow-up between the 2 groups. There was also no difference in secondary endpoints. The prevalence of de novo liver DSAs related to HLA mismatches was twice as high in the MSC group compared with the control group. All of the de novo class II HLA antibodies against MSCs were linked to a shared HLA mismatch between the liver and MSCs. This study confirms the safety of a single MSC infusion after LT. The potential benefits of MSC injections in the context of organ transplantation have yet to be demonstrated by larger prospective studies. The development of anti-HLA antibodies against an MSC donor should be further evaluated, especially in cases of shared HLA mismatches between graft and MSC donors, despite the fact that no deleterious effect has been detected.

3D bioassembly of cell-instructive chondrogenic and osteogenic hydrogel microspheres containing allogeneic stem cells for hybrid biofabrication of osteochondral constructs

Recently developed modular bioassembly techniques hold tremendous potential in tissue engineering and regenerative medicine, due to their ability to recreate the complex microarchitecture of native tissue. Here, we developed a novel approach to fabricate hybrid tissue-engineered constructs adopting high-throughput microfluidic and 3D bioassembly strategies. Osteochondral tissue fabrication was adopted as an example in this study, because of the challenges in fabricating load bearing osteochondral tissue constructs with phenotypically distinct zonal architecture. By developing cell-instructive chondrogenic and osteogenic bioink microsphere modules in high-throughput, together with precise manipulation of the 3D bioassembly process, we successfully fabricated hybrid engineered osteochondral tissue in vitro with integrated but distinct cartilage and bone layers. Furthermore, by encapsulating allogeneic umbilical cord blood-derived mesenchymal stromal cells (UCB-MSCs), and demonstrating chondrogenic and osteogenic differentiation, the hybrid biofabrication of hydrogel microspheres in this 3D bioassembly model offers potential for an off-the-shelf, single-surgery strategy for osteochondral tissue repair.

Tonsil mesenchymal stem cells-derived extracellular vesicles prevent submandibular gland dysfunction in ovariectomized rats

Dry mouth that occurs after menopause significantly reduces the quality of life of the elderly. The extracellular vesicles derived from mesenchymal stem cells are being studied for application in various pathological conditions in the field of tissue regenerative medicine. This study is to investigate the therapeutic effect on salivary gland dysfunction occurring after ovariectomy using tonsil mesenchymal stem cells (T-MSCs)-derived extracellular vesicles. The rats were divided into the following groups: sham-operated rats (SHAM), rats that underwent ovariectomy (OVX), and rats that underwent OVX surgery and were simultaneously injected with T-MSC-derived extracellular vesicles (OVX+EV). The rats were sacrificed 6 weeks after ovariectomy. Estradiol levels decreased in the OVX group compared with those in the SHAM group. Extracellular vesicles had no effect on estradiol levels or estrogen receptor β expression. The evaluation of pro-inflammatory cytokines, TNF-α and IL-6, increased in the OVX group and decreased in the OVX+EV group. The expressions of collagen I and TGFβI increased in the OVX group but decreased in the OVX+EV group. Moreover, to examine submandibular gland function, AQP5 and α-amylase expressions were downregulated in the OVX group, but improved upon exosome injection. In conclusion, T-MSC-derived extracellular vesicles are useful for the prevented submandibular gland dysfunction that occurs after menopause.

Alloreactivity of Allogeneic Mesenchymal Stem/Stromal Cells and Other Cellular Therapies: A Concise Review

Cellular therapies, deemed live medicine, have brought a wave of new generation biological therapies to treat previously untreatable diseases such as cancers and degenerative diseases like osteoarthritis. These cellular therapies have gained significant recognition in clinical research. The area has been further strengthened with the approval of Chimeric Antigen Receptor added on T cells (CAR-T) therapies by the regulatory authorities USA's Food and Drugs Administration (FDA), European Medical Agency (EMA), the Australian Therapeutic Goods Administration (TGA), and in many countries in 2017 to treat hematological cancers. Another milestone was achieved when allogeneic Mesenchymal Stem Cell- (MSC-) based therapy was approved by the EMA to treat Chrohn's disease in 2018. Allogeneic donor-derived MSC therapies in particular hold great promise and real hope because of their ‘off-the shelf' availability and accessibility for patients in need of urgent treatment. So far, thousands of clinical trials have explored the safety and efficacy of both autologous and allogeneic cell therapies, deeming them safe, however with varying degrees of efficacy. In the current pandemic, clinical trials have begun in many parts of the world to treat severe cases of COVID with MSCs. However, the risk of tissue rejection and the development of undesirable effects due to alloreactivity of allogeneic cells are currently not adequately addressed. Therefore, this warrants careful investigation and detailed reporting of such events by clinical researchers. This review aims at discussing the current landscape of approved allogeneic MSCs along with a few other cellular therapies. We explore any possible reactivity reported to inform the readers of any safety concern and on the efficacy of such therapies.

Stem Cell Therapy: From Idea to Clinical Practice

Regenerative medicine is a new and promising mode of therapy for patients who have limited or no other options for the treatment of their illness. Due to their pleotropic therapeutic potential through the inhibition of inflammation or apoptosis, cell recruitment, stimulation of angiogenesis, and differentiation, stem cells present a novel and effective approach to several challenging human diseases. In recent years, encouraging findings in preclinical studies have paved the way for many clinical trials using stem cells for the treatment of various diseases. The translation of these new therapeutic products from the laboratory to the market is conducted under highly defined regulations and directives provided by competent regulatory authorities. This review seeks to familiarize the reader with the process of translation from an idea to clinical practice, in the context of stem cell products. We address some required guidelines for clinical trial approval, including regulations and directives presented by the Food and Drug Administration (FDA) of the United States, as well as those of the European Medicine Agency (EMA). Moreover, we review, summarize, and discuss regenerative medicine clinical trial studies registered on the Clinicaltrials.gov website.

Periodontal Wound Healing and Regeneration: Insights for Engineering New Therapeutic Approaches

Periodontitis is a widespread inflammatory disease that leads to loss of the tooth supporting periodontal tissues. The few therapies available to regenerate periodontal tissues have high costs and inherent limitations, inspiring the development of new approaches. Studies have shown that periodontal tissues have an inherent capacity for regeneration, driven by multipotent cells residing in the periodontal ligament (PDL). The purpose of this review is to describe the current understanding of the mechanisms driving periodontal wound healing and regeneration that can inform the development of new treatment approaches. The biologic basis underlying established therapies such as guided tissue regeneration (GTR) and growth factor delivery are reviewed, along with examples of biomaterials that have been engineered to improve the effectiveness of these approaches. Emerging therapies such as those targeting Wnt signaling, periodontal cell delivery or recruitment, and tissue engineered scaffolds are described in the context of periodontal wound healing, using key in vivo studies to illustrate the impact these approaches can have on the formation of new cementum, alveolar bone, and PDL. Finally, design principles for engineering new therapies are suggested which build on current knowledge of periodontal wound healing and regeneration.

Therapeutic Mesenchymal Stem/Stromal Cells: Value, Challenges and Optimization

Cellular therapy aims to replace damaged resident cells by restoring cellular and molecular environments suitable for tissue repair and regeneration. Among several candidates, mesenchymal stem/stromal cells (MSCs) represent a critical component of stromal niches known to be involved in tissue homeostasis. In vitro, MSCs appear as fibroblast-like plastic adherent cells regardless of the tissue source. The therapeutic value of MSCs is being explored in several conditions, including immunological, inflammatory and degenerative diseases, as well as cancer. An improved understanding of their origin and function would facilitate their clinical use. The stemness of MSCs is still debated and requires further study. Several terms have been used to designate MSCs, although consensual nomenclature has yet to be determined. The presence of distinct markers may facilitate the identification and isolation of specific subpopulations of MSCs. Regarding their therapeutic properties, the mechanisms underlying their immune and trophic effects imply the secretion of various mediators rather than direct cellular contact. These mediators can be packaged in extracellular vesicles, thus paving the way to exploit therapeutic cell-free products derived from MSCs. Of importance, the function of MSCs and their secretome are significantly sensitive to their environment. Several features, such as culture conditions, delivery method, therapeutic dose and the immunobiology of MSCs, may influence their clinical outcomes. In this review, we will summarize recent findings related to MSC properties. We will also discuss the main preclinical and clinical challenges that may influence the therapeutic value of MSCs and discuss some optimization strategies.

A Robust and Highly Efficient Approach for Isolation of Mesenchymal Stem Cells From Wharton's Jelly for Tissue Repair

Mesenchymal stem cells derived from umbilical cord Wharton's Jelly (WJ-MSCs) are emerging as promising therapeutics for a variety of diseases due to their ability of regeneration and immunomodulation, and their non-tumorigenic and non-immunogenic properties. Although multiple protocols have been developed for WJ-MSC isolation, insufficient cell numbers, heterogeneous cell population, and variations in procedures between different laboratories impede further clinical applications. Here, we compared six widely used WJ-MSC isolation methods regarding cell morphology, yield, purity, proliferation rate, and differentiation potential. Based on these analyses, we identified that the inefficiency of the extracellular matrix digestion results in low cell yield. Thus, we developed a new method called "Mince-Soak-Digest (MSD)" to isolate MSCs from WJ by incorporating a soaking step to facilitate the digestion of the extracellular matrix and release of the cells. Our newly developed method generates significantly higher cell yield (4- to 10-fold higher) than six widely used methods that we tested with high purity and consistency. Importantly, by transplantation of WJ-MSCs to the rat uterus, we repair the endometrial injury and restore the fertility of the rats. In conclusion, our results provide a robust and highly efficient approach for the isolation of WJ-MSCs to restore injured tissue. The higher efficiency of MSD assures the abundance of WJ-MSCs for clinical applications. Furthermore, the reliability of MSD contributes to the standardization of WJ-MSC isolation, which eliminates the discrepancies due to isolation procedures, thus facilitating the evaluation of the efficacy of WJ-MSCs across various human clinical applications.

Directed Regeneration of Osteochondral Tissue by Hierarchical Assembly of Spatially Organized Composite Spheroids

The use of engineered scaffolds or stem cells is investigated widely in the repair of injured musculoskeletal tissue. However, the combined regeneration of hierarchical osteochondral tissue remains a challenge due to delamination between cartilage and subchondral bone or difficulty in spatial control over differentiation of transplanted stem cells. Here, two types of composite spheroids are prepared using adipose-derived stem cells (hADSCs) and nanofibers coated with either transforming growth factor-β3 or bone morphogenetic growth factor-2 for chondrogenesis or osteogenesis, respectively. Each type of spheroid is then cultured within a 3D-printed microchamber in a spatially arranged manner to recapitulate the bilayer structure of osteochondral tissue. The presence of inductive factors regionally modulates in vitro chondrogenic or osteogenic differentiation of hADSCs within the biphasic construct without dedifferentiation. Furthermore, hADSCs from each spheroid proliferate and sprout and successfully connect the two layers mimicking the osteochondral interface without apertures. In vivo transplantation of the biphasic construct onto a femoral trochlear groove defect in rabbit knee joint results in 21.2 ± 2.8% subchondral bone volume/total volume and a cartilage score of 25.0 ± 3.7. The present approach can be an effective therapeutic platform to engineer complex tissue.

OUP accepted manuscript

No effective therapy exists for the most common long-term side effect of radiation therapy for head and neck cancer (HNC)—xerostomia. The objective was to evaluate safety and provide proof of concept for efficacy of allogeneic adipose tissue-derived mesenchymal stem/stromal cells (AT-MSCs) injected into the major salivary glands of irradiated patients. This open-label, first-in-human, phase 1b, and single-center trial was conducted with repeated measurements days 0, 1, 5, and 30 and 4 months. Eligible patients with objective and subjective signs of radiation-induced salivary gland damage after treatment of oropharyngeal squamous cell carcinoma stages I-II (UICC 8) were enrolled. Twenty-five million cryopreserved AT-MSCs were injected into each submandibular and 50 million AT-MSCs into each parotid gland. Data were collected on adverse events, unstimulated and stimulated whole saliva (UWS and SWS) flow rates and saliva composition, patient-reported outcomes (EORTC QLQ-H&N35 and Xerostomia Questionnaire [XQ]), blood samples and salivary gland scintigraphy. Data were analyzed using repeated measures linear mixed models. Ten patients (7 men, 3 women, 59.5 years [range: 45-70]) were treated in 4 glands. No treatment-related serious adverse events occurred. During 4 months, UWS flow rate increased from 0.13 mL/minute at baseline to 0.18 mL/minute with a change of 0.06 (P = .0009) mL/minute. SWS flow rate increased from 0.66 mL/minute at baseline to 0.75 mL/minute with a change of 0.09 (P = .017) mL/minute. XQ summary score decreased by 22.6 units (P = .0004), EORTC QLQ-H&N35 dry mouth domains decreased by 26.7 (P = .0013), sticky saliva 23.3 (P = .0015), and swallowing 10.0 (P = .0016). Our trial suggests treatment of the major salivary glands with allogenic AT-MSCs is safe, warranting confirmation in larger trials.

Allogeneic adipose-derived mesenchymal stromal cell transplantation for refractory lupus nephritis: Results of a phase I clinical trial

BACKGROUND

Mesenchymal stromal/stem cells (MSCs) are known for their immunomodulatory properties. This study was performed to analyse the effects of MSC transplantation on treatment-resistant lupus nephritis (LN).

METHODS

In this phase I trial, nine biopsy-proven LN patients refractory to standard treatments underwent systemic infusion of 2 × 10⁶ allogeneic adipose-derived (AD) MSCs/kg and were followed for 12 months post-intervention.

RESULTS

The treatment protocol resulted in no major adverse events. Urine protein levels significantly decreased during the first month post-intervention (baseline vs. month 1 (median): 1800 vs. 1020, P = 0.008), followed by a gradual increase but remained significantly lower than baseline only up to the 3rd month. During the first 3 months post-intervention, complete renal response (proteinuria < 0.5 g/24 h) and partial response (proteinuria > 0.5 g/24 h, but > 50% decrease in proteinuria) were observed in 33.3% and 44.4% of the patients, respectively, though these rates declined thereafter. Median score of Systemic Lupus Erythematosus Disease Activity Index decreased significantly from 16 at the baseline to 6 at sixth months post-treatment (P = 0.007), though it slightly increased at the 12th month follow-up.

CONCLUSIONS

Allogenic AD-MSC transplantation was associated with favourable safety and efficient to reduce urine protein excretion and disease activity; however, the maximum effect (greatest improvement in outcomes) was observed at 1 month based on the proteinuria, and 6 months post-intervention based on disease activity scores. A single dose of AD-MSCs may not be adequate to maintain long-term remission of refractory LN, and so, additional doses may be required.