The mesenchymal stem cell secretome as an acellular regenerative therapy for liver disease

Milking mesenchymal stem cells: Updated protocols for cell lysate, secretome, and exosome extraction, and comparative analysis of their therapeutic potential

The potential of the cell lysate, secretome, and extracellular vesicles (EVs) of mesenchymal stem cells (MSCs) to modulate the immune response and promote tissue regeneration has positioned them as a promising option for cell-free therapy. Currently, many clinical trials in stem cells-derived EVs and secretome are in progress various diseases and sometimes the results are failing. The major challenge on this roadmap is the lack of a standard extraction method for exosome, secretome, and lysate. The most optimal method for obtaining the secretome of MSCs for clinical utilization involves a comprehensive approach that includes non-destructive collection methods, time optimization, multiple collection rounds, optimization of culture conditions, and quality control measures. Further research and clinical studies are warranted to validate and refine these methods for safe and effective utilization of the MSC exosome, secretome, and lysate in various clinical applications. To address these challenges, it is imperative to establish a standardized and unified methodology to ensure reliable evaluation of these extractions in clinical trials. This review seeks to outline the pros and cons of methods for the preparation of MSCs-derived exosome, and secretome/lysate, and comparative analysis of their therapeutic potential.

Transforming Myofibroblasts Into Lipid-Filled Cells to Treat Dupuytren Disease

PURPOSE

Transforming myofibroblasts (MFs) into adipocyte-like cells may be a viable option for treating Dupuytren disease. Human Dupuytren MFs (DMFs) and adipose-derived stem cells (ASCs) cocultured in the presence of platelet-rich plasma (PRP) reprogrammed into lipid-laden cells. This treatment also reduced fibrosis markers in vivo. We aimed to determine whether this treatment transformed DMFs into adipocyte-like cells in vivo and characterize the PRP factors contributing to this transformation.

METHODS

Dupuytren MFs and normal human dermal fibroblasts were transplanted into the forepaws of rats (Rowett Nude [rnu/rnu]). Two months later, the paws were treated with saline, ASCs + PRP, or Clostridium histolyticum (clinical comparison) once a week for three treatments. The paw tissue was harvested 1 week after each treatment and subjected to Masson trichrome staining, collagen I and III, α-smooth muscle actin (SMA), and perilipin detection by immunohistochemistry. Dupuytren MFs were cocultured with ASCs and PRP or insulin-like growth factor I (IGF-I) or IGF-I-depleted PRP. In addition, the IGF-I receptor was inhibited. Oil Red O or boron-dipyrromethene detected lipid-laden cells.

RESULTS

Rodent paws implanted with DMFs showed enhanced α-SMA expression, imbalanced collagen III:I ratio, and reduced adipocytes compared with normal human dermal fibroblasts. After treatment with ASCs + PRP, DMF paws demonstrated reduced α-SMA, a balanced collagen III:I ratio, and a replenishment of adipocytes. Dupuytren MFs treated with ASCs + IGF-I transformed into adipocyte-like cells in vitro, which was validated by IGF-I-depletion and IGF-I receptor inhibition.

CONCLUSIONS

Adipose-derived stem cells + PRP reduce fibrosis markers and induce adipocyte renewal in vivo. As a PRP component, IGF-I works with ASCs to transform DMFs into adipocyte-like cells in vitro.

CLINICAL RELEVANCE

Identifying an active factor in PRP that synergizes with ASCs to transform DMFs into adipocyte-like cells may contribute to finding a novel therapeutic for Dupuytren disease. Such a treatment may allow for less-extensive surgical intervention coupled with therapeutic injection to reduce the recurrence of Dupuytren disease.

Role of mesenchymal stromal cell secretome on recovery from cellular senescence: an overview

Cellular senescence is intricately linked with numerous changes observed in the aging process, including the depletion of the stem cell pool and the decline in tissue and organ functions. Over the past three decades, efforts to halt and reverse aging have intensified, bringing rejuvenation closer to reality. Current strategies involve treatments using stem cells or their derivatives, such as the secretome. This article aims to highlight key points and evaluate the utilization of secretome derived from mesenchymal stromal cells (MSCs) as an antisenescent approach. Employing a quasi-systematic research approach, the authors conducted a comprehensive analysis based on a search algorithm targeting the in vitro effects of MSC-derived secretome on rescuing cells from a senescent state. Reviewing 39 articles out of 687 hits retrieved from PubMed and Scopus without a time limit, the authors synthesized information and identified common types of MSC-tissue sources utilized (including bone marrow-MSCs, umbilical cord-MSCs, iPSC-derived MSCs, adipose tissue-MSCs, dental pulp-MSCs, amniotic membrane-MSCs, placenta-MSCs, gingival-MSCs, urine-MSCs, and commercially available MSC lineages) from both human and other species (such as mice and rats). The authors also examined the forms of secretome tested (including conditioned media and extracellular vesicles), the cell types treated (MSCs or other cell types), methods/biomarkers of monitoring senescence/rejuvenation, and the mechanisms involved. Ultimately, this review underscores the proof-of-principle of the beneficial effects of MSC-derived secretome in reversing cellular senescence across various cell types. Such insights might aid the scientific community in designing improved in vitro and in vivo assays for future research and clinical validation of this promising cell-free therapy.

The Secretome of the Inductive Tooth Germ Exhibits Signals Required for Tooth Development

Teeth develop from reciprocal signaling between inductive and receptive cells. The inductive signals for tooth development are initially in the epithelium of the developing branchial arch, but later shift to the underlying mesenchyme of a developing tooth germ. The inductive signals that are needed for tooth development have not yet been fully identified. Our lab previously provided a basis for bioengineering new teeth by separating the tooth germ's epithelial and mesenchyme cells into a single cell population and recombing them. This approach, however, is not clinically applicable as the cells lose their inductive ability when expanded in vitro. In this study, we investigate whether the secretome and small extracellular vehicles (sEV) derived from inductive tooth germ mesenchyme can contribute to inductive signals required for tooth development. To address this, small extracellular vesicles and secretome were purified from inductive tooth germ mesenchyme and characterized. We investigated the proteome of sEV and proteome of inductive tooth germ mesenchyme and the impact of the culture condition and duration on the proteome. Additionally, we investigated the transcriptomic changes in tooth germ epithelium after treatment with sEV from inductive tooth germ mesenchyme. We show that culture duration of inductive tooth germ mesenchyme has an impact on the proteome of sEV purified from these cells. Similarly, culturing these cells in 2D and 3D environments results in different protein content. Proteome unique to sEV derived from inductive shows an association with multiple signaling pathways related to tooth development. Our RNASeq results show that treatment of tooth germ epithelial cells with small extracellular vesicles derived from inductive tooth germ mesenchyme results in an increased expression of some of the known odontogenic genes. Whilst further analysis is required to harvest the full potential of these sEV, our results suggests that extracellular vehicles contribute to signals required during tooth development, potentially through modulation of cellular metabolism and ECM organization.

The paradigm of stem cell secretome in tissue repair and regeneration: Present and future perspectives

As the number of patients requiring organ transplants continues to rise exponentially, there is a dire need for therapeutics, with repair and regenerative properties, to assist in alleviating this medical crisis. Over the past decade, there has been a shift from conventional stem cell treatments towards the use of the secretome, the protein and factor secretions from cells. These components may possess novel druggable targets and hold the key to profoundly altering the field of regenerative medicine. Despite the progress in this field, clinical translation of secretome-containing products is limited by several challenges including but not limited to ensuring batch-to-batch consistency, the prevention of further heterogeneity, production of sufficient secretome quantities, product registration, good manufacturing practice protocols and the pharmacokinetic/pharmacodynamic profiles of all the components. Despite this, the secretome may hold the key to unlocking the regenerative blockage scientists have encountered for years. This review critically analyses the secretome derived from different cell sources and used in several tissues for tissue regeneration. Furthermore, it provides an overview of the current delivery strategies and the future perspectives for the secretome as a potential therapeutic. The success and possible shortcomings of the secretome are evaluated.

Cell therapy for end-stage liver disease: Current state and clinical challenge

ABSTRACT

Liver disease involves a complex interplay of pathological processes, including inflammation, hepatocyte necrosis, and fibrosis. End-stage liver disease (ESLD), such as liver failure and decompensated cirrhosis, has a high mortality rate, and liver transplantation is the only effective treatment. However, to overcome problems such as the shortage of donor livers and complications related to immunosuppression, there is an urgent need for new treatment strategies that need to be developed for patients with ESLD. For instance, hepatocytes derived from donor livers or stem cells can be engrafted and multiplied in the liver, substituting the host hepatocytes and rebuilding the liver parenchyma. Stem cell therapy, especially mesenchymal stem cell therapy, has been widely proved to restore liver function and alleviate liver injury in patients with severe liver disease, which has contributed to the clinical application of cell therapy. In this review, we discussed the types of cells used to treat ESLD and their therapeutic mechanisms. We also summarized the progress of clinical trials around the world and provided a perspective on cell therapy.

Mesenchymal stem cell-derived extracellular vesicles relieve endothelial cell senescence via recovering CTRP9 upon repressing miR-674-5p in atherosclerosis

Background

The senescence of endothelial cells is of great importance involving in atherosclerosis (AS) development. Recent studies have proved the protective role of mesenchymal stem cell-derived extracellular vesicles in AS, herein, we further desired to unvei their potential regulatory mechanisms in endothelial cell senescence.

Methods

Senescence induced by H2O2 in primary mouse aortic endothelial cells (MAECs) was evaluated by SA-β-gal staining. Targeted molecule expression was detected by qRT-PCR and Western blotting. The biological functions of MAECs were determined by CCK-8, flow cytometry, transwell, and tube formation assays. Oxidative injury was assessed by LDH, total and lipid ROS, LPO and MDA levels. The proliferation of adipose-derived mesenchymal stem cell (ADSCs) was analyzed by EdU assay. Effect of ADSCs-derived extracellular vesicles (ADSC-EVs) on AS was investigated in HFD-fed ApoE-/- mice.

Results

miR-674-5p was up-regulated, while C1q/TNF-related protein 9 (CTRP9) was down-regulated in H2O2-induced senescent MAECs. CTRP9 was demonstrated as a target gene of miR-674-5p. miR-674-5p inhibition restrained senescence, oxidative stress, promoted proliferation, migration, and angiogenesis of H2O2-stimulated MAECs via enhancing CTRP9 expression. Moreover, treatment with ADSC-EVs inhibited H2O2-induced senescence and dysfunction of MAECs through regulating miR-674-5p/CTRP9 axis. In the in vivo AS mouse model, ADSC-EVs combination with miR-674-5p silencing slowed down AS progression via up-regulation of CTRP9.

Conclusion

ADSC-EVs repressed endothelial cell senescence and improved dysfunction via promotion of CTRP9 expression upon miR-674-5p deficiency during AS progression, which might provide vital evidence for ADSC-EVs as a promising therapy for AS.

The Potential Role of Exosomes in Ocular Surface and Lacrimal Gland Regeneration

PURPOSE

Dry eye disease (DED), a multifactorial disease of the lacrimal system, manifests itself in patients with various symptoms such as itching, inflammation, discomfort and visual impairment. In its most severe forms, it results in the breakdown of the vital tissues of lacrimal functional unit and carries the risk of vision loss. Despite the frequency of occurrence of the disease, there are no effective curative treatment options available to date. Treatment using stem cells and its secreted factors could be a promising approach in the regeneration of damaged tissues of ocular surface. The treatment using secreted factors as well as extracellular vesicles has been demonstrated beneficial effects in various ocular surface diseases. This review provides insights on the usage of stem cell derived exosomes as a promising therapy against LG dysfunction induced ADDE for ocular surface repair.

METHODS

In order to gain an overview of the existing research in this field, literature search was carried out using the PubMed, Medline, Scopus and Web of Science databases. This review is based on 164 publications until June 2024 and the literature search was carried out using the key words "exosomes", "lacrimal gland regeneration", "exosomes in lacrimal dysfunction".

RESULTS

The literature and studies till date suggest that exosomes and other secreted factors from stem cells have demonstrated beneficial effects on damaged ocular tissues in various ocular surface diseases. Exosomal cargo plays a crucial role in regenerating tissues by promoting homeostasis in the lacrimal system, which is often compromised in severe cases of dry eye disease. Exosome therapy shows promise as a regenerative therapy, potentially addressing the lack of effective curative treatments available for patients with dry eye disease.

CONCLUSION

Stem cell-derived exosomes represent a promising, innovative approach as a new treatment option for ADDE. By targeting lacrimal gland dysfunction and enhancing ocular surface repair, exosome therapy offers potential for significant advances in dry eye disease management. Future research is needed to refine the application of this therapy, optimize delivery methods, and fully understand its long-term efficacy in restoring ocular health.

Wharton's Jelly mesenchymal stem cell-derived extracellular vesicles induce liver fibrosis-resolving phenotype in alternatively activated macrophages

The potential of extracellular vesicles (EVs) isolated from mesenchymal stromal cells in guiding macrophages toward anti-inflammatory immunophenotypes, has been reported in several studies. In our study, we provided experimental evidence of a distinctive effect played by Wharton Jelly mesenchymal stromal cell-derived EVs (WJ-EVs) on human macrophages. We particularly analyzed their anti-inflammatory effects on macrophages by evaluating their interactions with stellate cells, and their protective role in liver fibrosis. A three-step gradient method was used to isolate monocytes from umbilical cord blood (UCB). Two subpopulations of WJ-EVs were isolated by high-speed (20,000 g) and differential ultracentrifugation (110,000 g). Further to their characterization, they were designated as EV20K and EV110K and incubated at different concentrations with UCB-derived monocytes for 7 days. Their anti-fibrotic effect was assessed by studying the differentiation and functional levels of generated macrophages and their potential to modulate the survival and activity of LX2 stellate cells. The EV20K triggers the polarization of UCB-derived monocytes towards a peculiar M2-like functional phenotype more effectively than the M-CSF positive control. The EV20K treated macrophages were characterized by a higher expression of scavenger receptors, increased phagocytic capacity and production level of interleukin-10 and transforming growth factor-β. Conditioned medium from those polarized macrophages attenuated the proliferation, contractility and activation of LX2 stellate cells. Our data show that EV20K derived from WJ-MSCs induces activated macrophages to suppress immune responses and potentially play a protective role in the pathogenesis of liver fibrosis by directly inhibiting HSC's activation.

How Stem and Progenitor Cells Can Affect Renal Diseases

Stem and progenitor cells have been observed to contribute to regenerative processes in acute renal failure and chronic kidney disease. Recent research has delved into the intricate mechanisms by which stem and progenitor cells exert their influence on kidney diseases. Understanding how these cells integrate with the existing renal architecture and their response to injury could pave the way for innovative treatment strategies aimed at promoting kidney repair and regeneration. Overall, the role of stem and progenitor cells in kidney diseases is multifaceted, with their ability to contribute to tissue regeneration, immune modulation, and the maintenance of renal homeostasis. Here, we review the studies that we have available today about the involvement of stem and progenitor cells both in regenerative therapies and in the causes of renal diseases, as well as in natural healing mechanisms, taking into account the main kidney disorders, such as IgA nephropathy, lupus nephritis, diabetic nephropathy, C3 glomerulopathy, focal segmental glomerulosclerosis, idiopathic membranous nephropathy, anti-glomerular basement membrane glomerulonephritis, and ANCA-associated crescentic glomerulonephritis. Moreover, based on the comprehensive data available in the framework of the specific kidney diseases on stem cells and renal progenitors, we hypothesize a possible role of adult renal progenitors in exacerbating or recovering the illness.

Characterization of the Secretome from Spheroids of Adipose-Derived Stem Cells (SASCs) and Its Potential for Tissue Regeneration

INTRODUCTION

Spheroids are spherical aggregates of cells that mimic the three-dimensional (3D) architecture of tissues more closely than traditional two dimensional (2D) cultures. Spheroids of adipose stem cells (SASCs) show special features such as high multilineage differentiation potential and immunomodulatory activity. These properties have been attributed to their secreted factors, such as cytokines and growth factors. Moreover, a key role is played by the extracellular vesicles (EVs), which lead a heterogeneous cargo of proteins, mRNAs, and small RNAs that interfere with the pathways of the recipient cells.

PURPOSE

The aim of this work was to characterize the composition of the secretome and exosome from SASCs and evaluate their regenerative potential.

MATERIALS AND METHODS

SASCs were extracted from adipose samples of healthy individuals after signing informed consent. The exosomes were isolated and characterized by Dinamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and Western blotting analyses. The expression of mRNAs and miRNAs were evaluated through real-time PCR. Lastly, a wound-healing assay was performed to investigate their regenerative potential on different cell cultures.

RESULTS

The SASCs' exosomes showed an up-regulation of NANOG and SOX2 mRNAs, typical of stemness maintenance, as well as miR126 and miR146a, related to angiogenic and osteogenic processes. Moreover, the exosomes showed a regenerative effect.

CONCLUSIONS

The SASCs' secretome carried paracrine signals involved in stemness maintenance, pro-angiogenic and pro-osteogenic differentiation, immune system regulation, and regeneration.

Enhancing liver fibrosis diagnosis and treatment assessment: a novel biomechanical markers-based machine learning approach

Accurate diagnosis and treatment assessment of liver fibrosis face significant challenges, including inherent limitations in current techniques like sampling errors and inter-observer variability. Addressing this, our study introduces a novel machine learning (ML) framework, which integrates light gradient boosting machine and multivariate imputation by chained equations to enhance liver status assessment using biomechanical markers. Building upon our previously established multiscale mechanical characteristics in fibrotic and treated livers, this framework employs Gaussian Bayesian optimization for post-imputation, significantly improving classification performance. Our findings indicate a marked increase in the precision of liver fibrosis diagnosis and provide a novel, quantitative approach for assessing fibrosis treatment. This innovative combination of multiscale biomechanical markers with advanced ML algorithms represents a transformative step in liver disease diagnostics and treatment evaluation, with potential implications for other areas in medical diagnostics.

Mesenchymal Stromal Cells: New Generation Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract, which has a high recurrence rate and is incurable due to a lack of effective treatment. Mesenchymal stromal cells (MSCs) are a class of pluripotent stem cells that have recently received a lot of attention due to their strong self-renewal ability and immunomodulatory effects, and a large number of experimental and clinical models have confirmed the positive therapeutic effect of MSCs on IBD. In preclinical studies, MSC treatment for IBD relies on MSCs paracrine effects, cell-to-cell contact, and its mediated mitochondrial transfer for immune regulation. It also plays a therapeutic role in restoring the intestinal mucosal barrier through the homing effect, regulation of the intestinal microbiome, and repair of intestinal epithelial cells. In the latest clinical trials, the safety and efficacy of MSCs in the treatment of IBD have been confirmed by transfusion of autologous or allogeneic bone marrow, umbilical cord, and adipose MSCs, as well as their derived extracellular vesicles. However, regarding the stable and effective clinical use of MSCs, several concerns emerge, including the cell sources, clinical management (dose, route and frequency of administration, and pretreatment of MSCs) and adverse reactions. This article comprehensively summarizes the effects and mechanisms of MSCs in the treatment of IBD and its advantages over conventional drugs, as well as the latest clinical trial progress of MSCs in the treatment of IBD. The current challenges and future directions are also discussed. This review would add knowledge into the understanding of IBD treatment by applying MSCs.

A comprehensive review on the role of mesenchymal stromal/stem cells in the management of rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease with systemic manifestations. Although the success of immune modulatory drug therapy is considerable, about 40% of patients do not respond to treatment. Mesenchymal stromal/stem cells (MSCs) have been demonstrated to have therapeutic potential for inflammatory diseases.

AREAS COVERED

This review provides an update on RA disease and on pre-clinical and clinical studies using MSCs from bone marrow, umbilical cord, adipose tissue, and dental pulp, to regulate the immune response. Moreover, the clinical use, safety, limitations, and future perspective of MSCs in RA are discussed. Using the PubMed database and ClincalTrials.gov, peer-reviewed full-text papers, abstracts and clinical trials were identified from 1985 through to April 2023.

EXPERT OPINION

MSCs demonstrated a satisfactory safety profile and potential for clinical efficacy. However, it is mandatory to deepen the investigations on how MSCs affect the proinflammatory deregulated RA patients' cells. MSCs are potentially good candidates for severe RA patients not responding to conventional therapies but a long-term follow-up after stem cells treatment and standardized protocols are needed. Future research should focus on well-designed multicenter randomized clinical trials with adequate sample sizes and properly selected patients satisfying RA criteria for a valid efficacy evaluation.

Spinning with exosomes: electrospun nanofibers for efficient targeting of stem cell-derived exosomes in tissue regeneration

Electrospinning technique converts polymeric solutions into nanoscale fibers using an electric field and can be used for various biomedical and clinical applications. Extracellular vesicles (EVs) are cell-derived small lipid vesicles enriched with biological cargo (proteins and nucleic acids) potential therapeutic applications. In this review, we discuss extending the scope of electrospinning by incorporating stem cell-derived EVs, particularly exosomes, into nanofibers for their effective delivery to target tissues. The parameters used during the electrospinning of biopolymers limit the stability and functional properties of cellular products. However, with careful consideration of process requirements, these can significantly improve stability, leading to longevity, effectiveness, and sustained and localized release. Electrospun nanofibers are known to encapsulate or surface-adsorb biological payloads such as therapeutic EVs, proteins, enzymes, and nucleic acids. Small EVs, specifically exosomes, have recently attracted the attention of researchers working on regeneration and tissue engineering because of their broad distribution and enormous potential as therapeutic agents. This review focuses on current developments in nanofibers for delivering therapeutic cargo molecules, with a special emphasis on exosomes. It also suggests prospective approaches that can be adapted to safely combine these two nanoscale systems and exponentially enhance their benefits in tissue engineering, medical device coating, and drug delivery applications.

Therapeutic potential of exosome derived from hepatocyte growth factor-overexpressing adipose mesenchymal stem cells in TGFβ1-stimulated hepatic stellate cells

Cirrhosis is a familiar end-stage of multiple chronic liver diseases. The gene-modified mesenchymal stem cells (MSCs) have become one of the most promising schemes for the treatment of cirrhosis. MSCs exhibit their therapeutic role mainly by secreting hepatocyte growth factor (HGF). The aim of this research was to probe the anti-fibrosis role of exosomes secreted by HGF modified-mouse adipose MSCs (ADMSCs) on activated hepatic stellate cells (HSCs) and to preliminarily explore the possible mechanism. Firstly, mouse ADMSCs were isolated and identified. Quantitative real-time polymerase chain reaction verified the transfection efficiency of ADMSC transfected with HGF lentivirus. Exosomes derived from ADMSC transfecting negative control/HGF (ADMSCNC-Exo/ADMSCHGF-Exo) were extracted by density gradient centrifugation. HSCs were allocated to the control, TGF-β, TGF-β + ADMSC-Exo, TGF-β + ADMSCNC-Exo, and TGF-β + ADMSCHGF-Exo groups. Moreover, all mice were distributed to the control, CCl4 (40% CCl4 in olive oil), CCl4+ADMSC-Exo, CCl4+ADMSCNC-Exo, and CCl4+ADMSCHGF-Exo groups. Exosomes derived from ADMSCs with or without HGF transfection suppressed HSC activation, as evidenced by attenuating cell viability and cell cycle arrest at S phase but inducing apoptosis. Moreover, ADMSC-Exo, ADMSCNC-Exo, and ADMSCHGF-Exo effectively repressed the gene and protein levels of α-SMA, Col-I, Rho A, Cdc42, and Rac1 in TGF-β-treated HSCs, and ADMSCHGF-Exo had the best effect. ADMSCHGF-Exo had a stronger regulatory effect on serum liver index than ADMSCNC-Exo in CCl4-induced mice. In conclusion, ADMSCHGF-Exo alleviated liver fibrosis by weakening the Rho pathway, thus reducing collagen production.

Human umbilical cord/placenta mesenchymal stem cell conditioned medium attenuates intestinal fibrosis in vivo and in vitro

BACKGROUND

A significant unmet need in inflammatory bowel disease is the lack of anti-fibrotic agents targeting intestinal fibrosis. This study aimed to investigate the anti-fibrogenic properties and mechanisms of the conditioned medium (CM) from human umbilical cord/placenta-derived mesenchymal stem cells (UC/PL-MSC-CM) in a murine intestinal fibrosis model and human primary intestinal myofibroblasts (HIMFs).

METHODS

UC/PL-MSC-CM was concentrated 15-fold using a 3 kDa cut-off filter. C57BL/6 mice aged 7 weeks old were randomly assigned to one of four groups: (1) control, (2) dextran sulfate sodium (DSS), (3) DSS + CM (late-phase treatment), and (4) DSS + CM (early-phase treatment). Chronic DSS colitis and intestinal fibrosis was induced by three cycles of DSS administration. One DSS cycle consisted of 7 days of oral DSS administration (1.75%, 2%, and 2.5% DSS), followed by 14 days of drinking water. UC/PL-MSC-CM was intraperitoneally administered in the late phase (from day 50, 10 times) or early phase (from day 29, 10 times) of DSS cycles. HIMFs were treated with TGF-β1 and co-treated with UC/PL-MSC-CM (10% of culture media) in the cellular model.

RESULTS

In the animal study, UC/PL-MSC-CM reduced submucosa/muscularis propria thickness and collagen deposition, which improved intestinal fibrosis in chronic DSS colitis. The UC/PL-MSC-CM significantly reduced the expressions of procollagen1A1 and α-smooth muscle actin, which DSS significantly elevated. The anti-fibrogenic effect was more apparent in the UC-MSC-CM or early-phase treatment model. The UC/PL-MSC-CM reduced procollagen1A1, fibronectin, and α-smooth muscle actin expression in HIMFs in the cellular model. The UC/PL-MSC-CM downregulated fibrogenesis by suppressing RhoA, MRTF-A, and SRF expression.

CONCLUSIONS

Human UC/PL-MSC-CM inhibits TGF-β1-induced fibrogenic activation in HIMFs by blocking the Rho/MRTF/SRF pathway and chronic DSS colitis-induced intestinal fibrosis. Thus, it may be regarded as a novel candidate for stem cell-based therapy of intestinal fibrosis.

The Immunoregulatory and Regenerative Potential of Activated Human Stem Cell Secretome Mitigates Acute-on-Chronic Liver Failure in a Rat Model

Acute-on-chronic liver failure (ACLF) is a syndrome marked by sudden liver function decline and multiorgan failure, predominantly acute kidney injury (AKY), in patients with chronic liver disease. Unregulated inflammation is a hallmark of ACLF; however, the key drivers of ACLF are not fully understood. This study explores the therapeutic properties of human mesenchymal stem cell (MSC) secretome, particularly focusing on its enhanced anti-inflammatory and pro-regenerative properties after the in vitro preconditioning of the cells. We evaluated the efficacy of the systemic administration of MSC secretome in preventing liver failure and AKI in a rat ACLF model where chronic liver disease was induced using by the administration of porcine serum, followed by D-galN/LPS administration to induce acute failure. After ACLF induction, animals were treated with saline (ACLF group) or MSC-derived secretome (ACLF-secretome group). The study revealed that MSC-secretome administration strongly reduced liver histological damage in the ACLF group, which was correlated with higher hepatocyte proliferation, increased hepatic and systemic anti-inflammatory molecule levels, and reduced neutrophil and macrophage infiltration. Additionally, renal examination revealed that MSC-secretome treatment mitigated tubular injuries, reduced apoptosis, and downregulated injury markers. These improvements were linked to increased survival rates in the ACLF-secretome group, endorsing MSC secretomes as a promising therapy for multiorgan failure in ACLF.

Influential factors for optimizing and strengthening mesenchymal stem cells and hematopoietic stem cells co-culture

Mesenchymal stem cells (MSCs) and Hematopoietic stem cells (HSCs) are two types of bone marrow stem cells that can proliferate and differentiate into different cell lineages. HSCs interact with MSCs under protective conditions, called niche. Numerous studies have indicated supportive effects of MSCs on HSCs proliferation and differentiation. Furthermore, HSCs have many clinical applications and could treat different hematologic and non-hematologic diseases. For this purpose, there is a need to perform in vitro studies to optimize their expansion. Therefore, various methods including co-culture with MSCs are used to address the limitations of HSCs culture. Some parameters that might be effective for improving the MSC/ HSC co-culture systems. Manipulating culture condition to enhance MSC paracrine activity, scaffolds, hypoxia, culture medium additives, and the use of various MSC sources, have been examined in different studies. In this article, we investigated the potential factors for optimizing HSCs/ MSCs co-culture. It might be helpful to apply a suitable approach for providing high-quality HSCs and improving their therapeutic applications.

Evaluation of secretomes derived from human dermal and adipose tissue mesenchymal stem/stromal cells for skin wound healing: not as effective as cells

BACKGROUND

Although the paracrine effects of mesenchymal stem/stromal cells (MSCs) have been recognized as crucial mediators of their regenerative effects on tissue repair, the potential of MSC secretomes as effective substitutes for cellular therapies remains underexplored.

METHODS

In this study, we compared MSCs from the human dermis (DSCs) and adipose tissue (ASCs) with their secretomes regarding their efficacy for skin wound healing using a translationally relevant murine model.

RESULTS

Proteomic analysis revealed that while there was a substantial overlap in protein composition between DSC and ASC secretomes, specific proteins associated with wound healing and angiogenesis were differentially expressed. Despite a similar angiogenic potential in vivo, DSC and ASC secretomes were found to be less effective than cells in accelerating wound closure and promoting tissue remodeling.

CONCLUSIONS

Overall, secretome-treated groups showed intermediary results between cells- and control-treated (empty scaffold) groups. These findings highlight that although secretomes possess therapeutic potential, their efficacy might be limited compared to cellular therapies. This study contributes to the growing understanding of MSC secretomes, emphasizes the need for further protocol optimization, and offers insights into their potential applications in regenerative medicine.

Mechanical Unloading Promotes Osteoclastic Differentiation and Bone Resorption by Modulating the MSC Secretome to Favor Inflammation

Aging, space flight, and prolonged bed rest have all been linked to bone loss, and no effective treatments are clinically available at present. Here, with the rodent hindlimb unloading (HU) model, we report that the bone marrow (BM) microenvironment was significantly altered, with an increased number of myeloid cells and elevated inflammatory cytokines. In such inflammatory BM, the osteoclast-mediated bone resorption was greatly enhanced, leading to a shifted bone remodeling balance that ultimately ends up with disuse-induced osteoporosis. Using Piezo1 conditional knockout (KO) mice (Piezo1fl/fl;LepRCre), we proved that lack of mechanical stimuli on LepR+ mesenchymal stem cells (MSCs) is the main reason for the pathological BM inflammation. Mechanically, the secretome of MSCs was regulated by mechanical stimuli. Inadequate mechanical load leads to increased production of inflammatory cytokines, such as interleukin (IL)-1α, IL-6, macrophage colony-stimulating factor 1 (M-CSF-1), and so on, which promotes monocyte proliferation and osteoclastic differentiation. Interestingly, transplantation of 10% cyclic mechanical stretch (CMS)-treated MSCs into HU animals significantly alleviated the BM microenvironment and rebalanced bone remodeling. In summary, our research revealed a new mechanism underlying mechanical unloading-induced bone loss and suggested a novel stem cell-based therapy to potentially prevent disuse-induced osteoporosis.

Bone marrow mesenchymal stem cells-derived exosomes ameliorate LPS-induced acute lung injury by miR-223-regulated alveolar macrophage M2 polarization

Numerous studies have shown that the M2 polarization of alveolar macrophages (AM) plays a protective role in acute lung injury (ALI). Mesenchymal stem cells (MSCs) secreted exosomes have been reported to be involved in inflammatory diseases by the effects of polarized M1/M2 macrophage populations. However, whether bone marrow mesenchymal stem cells (BMMSCs) derived exosomes could protect from ALI and its mechanisms are still unclear. Here, we explored the role of exosomes from BMMSC in rat AM polarization and the lipopolysaccharide- (LPS-) induced ALI rat model. Furthermore, the levels of exosomal miR-223 in BMMSCs were measured by RT-qPCR. Additionally, miR-223 mimics and its inhibitors were used to verify the vital role of miR-223 of BMMSCs-derived exosomes in the polarization of M2 macrophages. The results showed that BMMSCs-derived exosomes were taken up by the AM. Exosomes derived from BMMSCs promoted M2 polarization of AM in vitro. BMMSCs exosomes effectively mitigated pathological injuries, lung edema, and the inflammation of rats from LPS-induced ALI, accompanied by an increase of M2 polarization of AM in lung tissue. Interestingly, we also found that miR-223 was enriched in BMMSCs-derived exosomes, and overexpression of miR-223 in BMMSCs-derived exosomes promoted M2 polarization of AM while depressing miR-223 showed opposite effects in AM. The present study demonstrated that BMMSCs-derived exosomes triggered alveolar M2 polarization to improve inflammation by transferring miR-223, which may provide new therapeutic strategies in ALI.

Repairing Effect of Mesenchymal Stem Cells on Lead Acetate-Induced Testicular Injury in Mice

Lead acetate can cause testicular damage in males. In this study, we assessed the repairing effects of human umbilical cord mesenchymal stem cells (MSCs) on testicular injury caused by lead acetate in mice. MSCs were injected into mice with testicular injury by intraperitoneal injection, and the organ coefficient of reproductive organs, sperm motility, hormone level and antioxidant index of mice were tested. Compared with the normal group, the coefficient of reproductive organs and sperm motility were reduced in the model group, and histopathology showed obvious testicular injury, proving successful modeling. Compared with the model group, the reproductive organ coefficient and sperm motility were improved in the experimental group, and histopathology showed that the testicular injury could be significantly improved. Sex hormone secretion tends to be normal, and the antioxidant index increased. Sequencing results showed that there were 485 upregulated genes and 172 downregulated genes between the model group and the control group, and 210 upregulated genes and 482 downregulated genes between the experimental group and the model group. Differentially expressed genes are mainly concentrated in AMP-activated protein kinase (AMPK) signaling pathway, apoptosis signaling pathway, and arginine biosynthesis signaling pathway. Overall, MSCs can significantly improve the degree of damages to mice testis caused by lead acetate and have a certain repairing effect.

New era of mesenchymal stem cell-based medicine: basis, challenges and prospects

Stem cells of mesenchymal origin (MSC) arouse special interest due to their regenerative, anti-inflammatory, anti-apoptotic, anti-oxidative stress, antitumor or antimicrobial properties. However, its implementation in the clinic runs into drawbacks of cell therapy (immunological incompatibility, tumor formation, possible transmission of infections, entry into cellular senescence, difficult evaluation of safety, dose and potency; complex storage conditions, high economic cost or impractical clinical use). Considering that the positive effects of MSC are due, to a large extent, to the paracrine effects mediated by the set of substances they secrete (growth factors, cytokines, chemokines or microvesicles), the in vitro obtaining of these biological products makes possible a medicine cell-free regenerative therapy without the drawbacks of cell therapy. However, this new therapeutic innovation implies challenges, such as the recognition of the biological heterogeneity of MSC and the optimization and standardization of their secretome.

Bone marrow mesenchymal stem cell‑derived exosomes: A novel therapeutic agent for tendon‑bone healing (Review)

In sports medicine, injuries related to the insertion of tendons into bones, including rotator cuff injuries, anterior cruciate ligament injuries and Achilles tendon ruptures, are commonly observed. However, traditional therapies have proven to be insufficient in achieving satisfactory outcomes due to the intricate anatomical structure associated with these injuries. Adult bone marrow mesenchymal stem cells possess self‑renewal and multi‑directional differentiation potential and can generate various mesenchymal tissues to aid in the recovery of bone, cartilage, adipose tissue and bone marrow hematopoietic tissue. In addition, extracellular vesicles derived from bone marrow mesenchymal stem cells known as exosomes, contain lipids, proteins and nucleic acids that govern the tissue microenvironment, facilitate tissue repair and perform various biological functions. Studies have demonstrated that bone marrow mesenchymal stem cell‑derived exosomes can function as natural nanocapsules for drug delivery and can enhance tendon‑bone healing strength. The present review discusses the latest research results on the role of exosomes released by bone marrow mesenchymal stem cells in tendon‑bone healing and provides valuable information for implementing these techniques in regenerative medicine and sports health.

Dual impacts of mesenchymal stem cell-derived exosomes on cancer cells: unravelling complex interactions

Mesenchymal stem cells (MSCs) are multipotent, self-renewing stromal cells found in a variety of adult tissues. MSCs possess a remarkable ability to migrate towards tumor sites, known as homing. This homing process is mediated by various factors, including chemokines, growth factors, and extracellular matrix components present in the tumor microenvironment. MSCs release extracellular vesicles known as exosomes (MSC-Exos), which have been suggested to serve a key role in mediating a wide variety of MSC activities. Through cell-cell communication, MSC-Exos have been shown to alter recipient cell phenotype or function and play as a novel cell-free alternative for MSC-based cell therapy. However, MSC recruitment to tumors allows for their interaction with cancer cells and subsequent regulation of tumor behavior. MSC-Exos act as tumor niche modulators via transferring exosomal contents, such as specific proteins or genetic materials, to the nearby cancer cells, leading to either promotion or suppression of tumorigenesis, angiogenesis, and metastasis, depending on the specific microenvironmental cues and recipient cell characteristics. Consequently, there is still a debate about the precise relationship between tumor cells and MSC-Exos, and it is unclear how MSC-Exos impacts tumor cells. Although the dysregulation of miRNAs is caused by the progression of cancer, they also play a direct role in either promoting or inhibiting tumor growth as they act as either oncogenes or tumor suppressors. The utilization of MSC-Exos may prove to be an effective method for restoring miRNA as a means of treating cancer. This review aimed to present the existing understanding of the impact that MSC-Exos could have on cancer. To begin with, we presented a brief explanation of exosomes, MSCs, and MSC-Exos. Following this, we delved into the impact of MSC-Exos on cancer growth, EMT, metastasis, angiogenesis, resistance to chemotherapy and radiotherapy, and modulation of the immune system. Opposing effects of mesenchymal stem cells-derived exosomes on cancer cells.

Stem cell therapy for hepatocellular carcinoma and end-stage liver disease

Hepatocellular carcinoma (HCC) is a major health problem worldwide, especially for patients who are suffering from end-stage liver disease (ESLD). The ESLD is considered a great challenge for clinicians due to the limited chance for liver transplantation, which is the only curative treatment for those patients. Stem cell-based therapy as a part of regenerative medicine represents a promising application for ESLD patients. Many clinical trials were performed to assess the utility of bone marrow-derived stem cells as a potential therapy for patients with liver diseases. The aim of the present study is to present and review the various types of stem cell-based therapy, including the mesenchymal stem cells (MSCs), BM-derived mononuclear cells (BM-MNCs), CD34 + hematopoietic stem cells (HSCs), induced pluripotent stem cells (iPSCs), and cancer stem cells.Though this type of therapy achieved promising results for the treatment of ESLD, however still there is a confounding data regarding its clinical application. A large body of evidence is highly required to evaluate the stem cell-based therapy after long-term follow-up, with respect to the incidence of toxicity, immunogenicity, and tumorigenesis that developed in many patients.

Efficacy and safety of mesenchymal stem cell therapy in liver cirrhosis: a systematic review and meta-analysis

AIM

Although the efficacy and safety of mesenchymal stem cell therapy for liver cirrhosis have been demonstrated in several studies. Clinical cases of mesenchymal stem cell therapy for patients with liver cirrhosis are limited and these studies lack the consistency of treatment effects. This article aimed to systematically investigate the efficacy and safety of mesenchymal stem cells in the treatment of liver cirrhosis.

METHOD

The data source included PubMed/Medline, Web of Science, EMBASE, and Cochrane Library, from inception to May 2023. Literature was screened by the PICOS principle, followed by literature quality evaluation to assess the risk of bias. Finally, the data from each study's outcome indicators were extracted for a combined analysis. Outcome indicators of the assessment included liver functions and adverse events. Statistical analysis was performed using Review Manager 5.4.

RESULTS

A total of 11 clinical trials met the selection criteria. The pooled analysis' findings demonstrated that both primary and secondary indicators had improved. Compared to the control group, infusion of mesenchymal stem cells significantly increased ALB levels in 2 weeks, 1 month, 3 months, and 6 months, and significantly decreased MELD score in 1 month, 2 months, and 6 months, according to a subgroup analysis using a random-effects model. Additionally, the hepatic arterial injection favored improvements in MELD score and ALB levels. Importantly, none of the included studies indicated any severe adverse effects.

CONCLUSION

The results showed that mesenchymal stem cell was effective and safe in the treatment of liver cirrhosis, improving liver function (such as a decrease in MELD score and an increase in ALB levels) in patients with liver cirrhosis and exerting protective effects on complications of liver cirrhosis and the incidence of hepatocellular carcinoma. Although the results of the subgroup analysis were informative for the selection of mesenchymal stem cells for clinical treatment, a large number of high-quality randomized controlled trials validations are still needed.

Hipoxia modulates the secretion of growth factors of human umbilical cord-derived mesenchymal stem cells

Background

Mesenchymal stem cell (MSC) has great potential as therapies due its ability to regenerate tissue damage and promote tissue homeostasis. Preconditioning of MSC in low oxygen concentration has been shown to affect the therapeutic potential of these cells. This study aimed to compare the characteristic and secretion of trophic factors of MSCs cultured under hypoxia and normoxia.

Methods

MSCs were isolated from Wharton's jelly of human umbilical cord (UC) tissue by explant method and characterized by flow cytometry. Following 24 h of CoCl2-induced hypoxic culture, the viability and metabolic activity of MSC were analyzed by trypan blue exclusion test and methyl thiazolyl tetrazolium (MTT) assay, respectively. The secretion of hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) was assessed in conditioned medium using enzyme-linked immunosorbent assay (ELISA) method.

Results

Flow cytometry analysis showed >99% of the population of MSCs cells were positive for CD73 and CD90 and > 62% were positive for CD105. While the cell viability of MSC was not affected by hypoxic cultured condition, the metabolic activity rate of these cells was decreased under hypoxic conditioning. In line with reduced metabolic activity, hypoxic human UC-derived MSC produced less HGF than normoxic counterpart. Compared to normoxic MSC, hypoxic preconditioned MSC secreted higher level of VEGF in the conditioned medium (p < 0.05).

Conclusions

Hypoxia decreased the metabolic activity of MSCs associated with the modulation of HGF and VEGF secretions. It is suggested that hypoxia may also affect the therapeutic capacity of MSC cells.

Targeting Myofibroblasts as a Treatment Modality for Dupuytren Disease

PURPOSE

Currently, no treatment corrects the contractile nature of Dupuytren myofibroblasts (DMFs) or prevents recurrence following surgery. Antifibrotic and proadipogenic growth factors are released when adipose-derived stem cells (ASCs) are cultured with platelet-rich plasma (PRP), a platelet concentration from whole blood. Reprograming myofibroblasts into adipocytes via growth factors is proposed as a powerful potential tool to target fibrosis. We aimed to assess whether the combination of ASCs and PRP reprograms DMFs into adipocytes in vitro and alters their contractile nature in vivo.

METHODS

Normal human dermal fibroblasts (NHDFs) and DMFs from Dupuytren patients were isolated and cocultured with ASCs and PRP either alone or together. Adipocytes were detected by Oil Red O and perilipin staining. DMFs and NHDFs were transplanted into the forepaws of rats (Rowett Nude [rnu/rnu]) and treated with saline, PRP+ASCs, or collagenase Clostridium histolyticum (clinical comparison) 2 months later. After 2 weeks, the tissue was harvested and subjected to Masson trichrome staining, and collagen I and III and alpha-smooth muscle actin detection by immunohistochemistry.

RESULTS

Myofibroblasts transform into adipocytes upon coculture with PRP+ASCs. DMFs show increased alpha-smooth muscle actin expression in vivo compared with NHDFs, which is significantly decreased after PRP+ASCs and collagenase Clostridium histolyticum treatments. DMFs induce collagen I and III expressions in rat paws compared with NHDFs, with a type III to I ratio increase. Treatment with PRP+ASC reduced the ratio, but collagenase Clostridium histolyticum did not.

CONCLUSIONS

Treating DMFs with PRP+ASCs provides factors that induce myofibroblast to adipocyte transformation. This treatment reduces the contractile phenotype and fibrosis markers in vivo. Future studies should detail the mechanism of this conversion.

CLINICAL RELEVANCE

The combination of PRP and ASCs to induce the differentiation of DMFs into adipocytes may serve to limit surgery to a percutaneous contracture release and biological injection, rather than a moderate or radical fasciectomy, and reduce the recurrence of Dupuytren contracture.

Liver Disease and Cell Therapy: Advances Made and Remaining Challenges

The limited availability of organs for liver transplantation, the ultimate curative treatment for end stage liver disease, has resulted in a growing and unmet need for alternative therapies. Mesenchymal stromal cells (MSCs) with their broad ranging anti-inflammatory and immunomodulatory properties have therefore emerged as a promising therapeutic agent in treating inflammatory liver disease. Significant strides have been made in exploring their biological activity. Clinical application of MSC has shifted the paradigm from using their regenerative potential to one which harnesses their immunomodulatory properties. Reassuringly, MSCs have been extensively investigated for over 30 years with encouraging efficacy and safety data from translational and early phase clinical studies, but questions remain about their utility. Therefore, in this review, we examine the translational and clinical studies using MSCs in various liver diseases and their impact on dampening immune-mediated liver damage. Our key observations include progress made thus far with use of MSCs for clinical use, inconsistency in the literature to allow meaningful comparison between different studies and need for standardized protocols for MSC manufacture and administration. In addition, the emerging role of MSC-derived extracellular vesicles as an alternative to MSC has been reviewed. We have also highlighted some of the remaining clinical challenges that should be addressed before MSC can progress to be considered as therapy for patients with liver disease.

Therapeutic Potential of Mesenchymal Stem Cell-Derived Extracellular Vesicles to Treat PCOS

Polycystic ovary syndrome (PCOS) is known as the most common endocrine disorder in women. Previously, we suggested that human mesenchymal stem cells (MSCs) can reverse the PCOS condition by secreting factors. Here, we evaluated the therapeutic capability of MSC-derived extracellular vesicles (EVs), also known as exosomes, in both in vitro and in vivo PCOS models. Exosomes were used to treat androgen-producing H293R cells and injected in a mouse model through intraovarian and intravenous injection into a letrozole (LTZ)-induced PCOS mouse model. We assessed the effects of the exosomes on androgen-producing cells or the PCOS mouse model by analyzing steroidogenic gene expression (quantitative real-time polymerase chain reaction (qRT-PCR)), body weight change, serum hormone levels, and fertility by pup delivery. Our data show the therapeutic effect of MSC-derived EVs for reversing PCOS conditions, including fertility issues. Interestingly, intravenous injection was more effective for serum glucose regulation, and an intraovarian injection was more effective for ovary restoration. Our study suggests that MSC-derived exosomes can be promising biopharmaceutics for treating PCOS conditions as a novel therapeutic option. Despite the fact that we need more validation in human patients, we may evaluate this novel treatment option for PCOS with the following clinical trials.

Comparison of two hepatocyte differentiation protocols in human umbilical cord mesenchymal stem cells: In vitro study

Human umbilical cord mesenchymal stromal cells (HUCMSCs) are an emerging source of cell therapy due to their self-renew and differentiation ability. They can differentiate into three germ layers, including the potential to generate hepatocytes. This study determined the transplantation efficiency and suitability of HUCMSCs-derived hepatocyte-like cells (HLCs) for their therapeutic application for liver diseases. This study aims to formulate ideal conditions to induce HUCMSCs into the hepatic lineage and investigate the efficiency of the differentiated HLCs based on their expression characteristics and capacity to integrate into the damaged liver of CCl4-challenged mice. Hepatocyte growth factor (HGF) and Activin A, Wnt3a were found to optimally promote the endodermal expansion of HUCMSCs, which showed phenomenal expression of hepatic markers upon differentiation in the presence of oncostatin M and dexamethasone. HUCMSCs expressed MSC-related surface markers and could undergo tri-lineage differentiations. Two hepatogenic differentiation protocols (differentiated hepatocyte protocol 1 [DHC1]: 32 days and DHC2: 15 days) were experimented with. The proliferation rate was faster in DHC2 than in DHC1 on day 7 of differentiation. The migration capability was the same in both DHC1 and DHC2. Hepatic markers like CK18, CK19, ALB, and AFP were upregulated. The mRNA levels of albumin, α1AT, αFP, CK18, TDO2, CYP3A4, CYP7A1, HNF4A, CEBPA, PPARA, and PAH were even higher in the HUCMSCs-derived HCLs than in the primary hepatocytes. Western blot confirmed HNF3B and CK18 protein expression in a step-wise manner differentiated from HUCMSCs. The metabolic function of differentiated hepatocytes was evident by increasing PAS staining and urea production. Pre-treating HUCMSCs with a hepatic differentiation medium containing HGF can drive their differentiation towards endodermal and hepatic lineages, enabling efficient integration into the damaged liver. This approach represents a potential alternative protocol for cell-based therapy that could enhance the integration potential of HUCMSC-derived HLCs.

Wharton's jelly mesenchymal stem cells: a concise review of their secretome and prospective clinical applications

Accumulating evidence indicates that most primary Wharton's jelly mesenchymal stem cells (WJ-MSCs) therapeutic potential is due to their paracrine activity, i.e., their ability to modulate their microenvironment by releasing bioactive molecules and factors collectively known as secretome. These bioactive molecules and factors can either be released directly into the surrounding microenvironment or can be embedded within the membrane-bound extracellular bioactive nano-sized (usually 30-150 nm) messenger particles or vesicles of endosomal origin with specific route of biogenesis, known as exosomes or carried by relatively larger particles (100 nm-1 μm) formed by outward blebbing of plasma membrane called microvesicles (MVs); exosomes and MVs are collectively known as extracellular vesicles (EVs). The bioactive molecules and factors found in secretome are of various types, including cytokines, chemokines, cytoskeletal proteins, integrins, growth factors, angiogenic mediators, hormones, metabolites, and regulatory nucleic acid molecules. As expected, the secretome performs different biological functions, such as immunomodulation, tissue replenishment, cellular homeostasis, besides possessing anti-inflammatory and anti-fibrotic effects. This review highlights the current advances in research on the WJ-MSCs' secretome and its prospective clinical applications.

Mesenchymal stromal cells in hepatic fibrosis/cirrhosis: from pathogenesis to treatment

Hepatic fibrosis/cirrhosis is a significant health burden worldwide, resulting in liver failure or hepatocellular carcinoma (HCC) and accounting for many deaths each year. The pathogenesis of hepatic fibrosis/cirrhosis is very complex, which makes treatment challenging. Endogenous mesenchymal stromal cells (MSCs) have been shown to play pivotal roles in the pathogenesis of hepatic fibrosis. Paradoxically, exogenous MSCs have also been used in clinical trials for liver cirrhosis, and their effectiveness has been observed in most completed clinical trials. There are still many issues to be resolved to promote the use of MSCs in the clinic in the future. In this review, we will examine the controversial role of MSCs in the pathogenesis and treatment of hepatic fibrosis/cirrhosis. We also investigated the clinical trials involving MSCs in liver cirrhosis, summarized the parameters that need to be standardized, and discussed how to promote the use of MSCs from a clinical perspective.

Bone marrow mesenchymal stem cell-derived small extracellular vesicles promote liver regeneration via miR-20a-5p/PTEN

Balancing hepatocyte death and proliferation is key to non-transplantation treatments for acute liver failure (ALF), which has a high short-term mortality rate. Small extracellular vesicles (sEVs) may act as mediators in the repair of damaged liver tissue by mesenchymal stem cells (MSCs). We aimed to investigate the efficacy of human bone marrow MSC-derived sEVs (BMSC-sEVs) in treating mice with ALF and the molecular mechanisms involved in regulating hepatocyte proliferation and apoptosis. Small EVs and sEV-free BMSC concentrated medium were injected into mice with LPS/D-GalN-induced ALF to assess survival, changes in serology, liver pathology, and apoptosis and proliferation in different phases. The results were further verified in vitro in L-02 cells with hydrogen peroxide injury. BMSC-sEV-treated mice with ALF had higher 24 h survival rates and more significant reductions in liver injury than mice treated with sEV-free concentrated medium. BMSC-sEVs reduced hepatocyte apoptosis and promoted cell proliferation by upregulating miR-20a-5p, which targeted the PTEN/AKT signaling pathway. Additionally, BMSC-sEVs upregulated the mir-20a precursor in hepatocytes. The application of BMSC-sEVs showed a positive impact by preventing the development of ALF, and may serve as a promising strategy for promoting ALF liver regeneration. miR-20a-5p plays an important role in liver protection from ALF by BMSC-sEVs.

Effect of Hepatic Pathology on Liver Regeneration: The Main Metabolic Mechanisms Causing Impaired Hepatic Regeneration

Liver regeneration has been studied for many decades, and the mechanisms underlying regeneration of normal liver following resection are well described. However, no less relevant is the study of mechanisms that disrupt the process of liver regeneration. First of all, a violation of liver regeneration can occur in the presence of concomitant hepatic pathology, which is a key factor reducing the liver's regenerative potential. Understanding these mechanisms could enable the rational targeting of specific therapies to either reduce the factors inhibiting regeneration or to directly stimulate liver regeneration. This review describes the known mechanisms of normal liver regeneration and factors that reduce its regenerative potential, primarily at the level of hepatocyte metabolism, in the presence of concomitant hepatic pathology. We also briefly discuss promising strategies for stimulating liver regeneration and those concerning methods for assessing the regenerative potential of the liver, especially intraoperatively.

Revolutionizing Radiotoxicity Management with Mesenchymal Stem Cells and Their Derivatives: A Focus on Radiation-Induced Cystitis

Although radiation therapy plays a crucial role in cancer treatment, and techniques have improved continuously, irradiation induces side effects in healthy tissue. Radiation cystitis is a potential complication following the therapeutic irradiation of pelvic cancers and negatively impacts patients' quality of life (QoL). To date, no effective treatment is available, and this toxicity remains a therapeutic challenge. In recent times, stem cell-based therapy, particularly the use of mesenchymal stem cells (MSC), has gained attention in tissue repair and regeneration due to their easy accessibility and their ability to differentiate into several tissue types, modulate the immune system and secrete substances that help nearby cells grow and heal. In this review, we will summarize the pathophysiological mechanisms of radiation-induced injury to normal tissues, including radiation cystitis (RC). We will then discuss the therapeutic potential and limitations of MSCs and their derivatives, including packaged conditioned media and extracellular vesicles, in the management of radiotoxicity and RC.

Mesenchymal Stromal Cells as a Driver of Inflammaging

Life expectancy and age-related diseases burden increased significantly over the past few decades. Age-related conditions are commonly discussed in a very limited paradigm of depleted cellular proliferation and maturation with exponential accumulation of senescent cells. However, most recent evidence showed that the majority of age-associated ailments, i.e., diabetes mellitus, cardiovascular diseases and neurodegeneration. These diseases are closely associated with tissue nonspecific inflammation triggered and controlled by mesenchymal stromal cell secretion. Mesenchymal stromal cells (MSCs) are known as the most common type of cells for therapeutic approaches in clinical practice. Side effects and complications of MSC-based treatments increased interest in the MSCs secretome as an alternative concept for validation tests in regenerative medicine. The most recent data also proposed it as an ideal tool for cell-free regenerative therapy and tissue engineering. However, senescent MSCs secretome was shown to hold the role of ‘key-driver’ in inflammaging. We aimed to review the immunomodulatory effects of the MSCs-secretome during cell senescence and provide eventual insight into the interpretation of its beneficial biological actions in inflammaging-associated diseases.

Impact of umbilical cord mesenchymal stromal/stem cell secretome and cord blood serum in prostate cancer progression

Prostate cancer (PCa) is the second most common malignancy in men, and the fifth leading cause of death worldwide. Mesenchymal stromal/stem cells (MSC) have been identified in PCa, although contradictory effects in malignant transformation and tumor progression have been described. Since umbilical cord (UC) MSC and cord blood serum (CBS) are rich in numerous growth and anti-inflammatory factors, UC-MSC secretome and CBS are able to modulate tumor cell proliferation and survival as well as immunity and angiogenesis. In the present study, we address this relationship and investigate the influence of UC-MSC secretome and CBS on two human PCa cell lines (PC3 and LNCaP) and a normal epithelial prostate cell line (HPEpiC). Our results disclosed that upon exposure to UC-MSC-conditioned medium or CBS, both PC3 and LNCaP cells exhibited reduced viability, proliferation, and motility while non-malignant epithelial prostate cells were unaffected. These findings were corroborated by expression analysis of AKT/PI3K signaling pathway, p53 and interleukin genes. UC-MSC and CBS factors decreased the expression of growth-stimulating AKT and PI3K effectors and simultaneously up-regulated the expression of tumor-suppressor p53. Moreover, a more anti-inflammatory expression profile was found in both malignant PCa cell lines. Altogether, these results shed light into possible mechanisms by which UC-MSC and CBS reduce PCa progression, further reinforcing their potential use as novel therapeutic agents in PCa.

Administration of Secretome Derived from Human Mesenchymal Stem Cells Induces Hepatoprotective Effects in Models of Idiosyncratic Drug-Induced Liver Injury Caused by Amiodarone or Tamoxifen

Drug-induced liver injury (DILI) is one of the leading causes of acute liver injury. While many factors may contribute to the susceptibility to DILI, obese patients with hepatic steatosis are particularly prone to suffer DILI. The secretome derived from mesenchymal stem cell has been shown to have hepatoprotective effects in diverse in vitro and in vivo models. In this study, we evaluate whether MSC secretome could improve DILI mediated by amiodarone (AMI) or tamoxifen (TMX). Hepatic HepG2 and HepaRG cells were incubated with AMI or TMX, alone or with the secretome of MSCs obtained from human adipose tissue. These studies demonstrate that coincubation of AMI or TMX with MSC secretome increases cell viability, prevents the activation of apoptosis pathways, and stimulates the expression of priming phase genes, leading to higher proliferation rates. As proof of concept, in a C57BL/6 mouse model of hepatic steatosis and chronic exposure to AMI, the MSC secretome was administered endovenously. In this study, liver injury was significantly attenuated, with a decrease in cell infiltration and stimulation of the regenerative response. The present results indicate that MSC secretome administration has the potential to be an adjunctive cell-free therapy to prevent liver failure derived from DILI caused by TMX or AMI.

Therapeutic potential and mechanisms of mesenchymal stem cell-derived exosomes as bioactive materials in tendon-bone healing

Tendon-bone insertion (TBI) injuries, such as anterior cruciate ligament injury and rotator cuff injury, are the most common soft tissue injuries. In most situations, surgical tendon/ligament reconstruction is necessary for treating such injuries. However, a significant number of cases failed because healing of the enthesis occurs through scar tissue formation rather than the regeneration of transitional tissue. In recent years, the therapeutic potential of mesenchymal stem cells (MSCs) has been well documented in animal and clinical studies, such as chronic paraplegia, non-ischemic heart failure, and osteoarthritis of the knee. MSCs are multipotent stem cells, which have self-renewability and the ability to differentiate into a wide variety of cells such as chondrocytes, osteoblasts, and adipocytes. Numerous studies have suggested that MSCs could promote angiogenesis and cell proliferation, reduce inflammation, and produce a large number of bioactive molecules involved in the repair. These effects are likely mediated by the paracrine mechanisms of MSCs, particularly through the release of exosomes. Exosomes, nano-sized extracellular vesicles (EVs) with a lipid bilayer and a membrane structure, are naturally released by various cell types. They play an essential role in intercellular communication by transferring bioactive lipids, proteins, and nucleic acids, such as mRNAs and miRNAs, between cells to influence the physiological and pathological processes of recipient cells. Exosomes have been shown to facilitate tissue repair and regeneration. Herein, we discuss the prospective applications of MSC-derived exosomes in TBI injuries. We also review the roles of MSC-EVs and the underlying mechanisms of their effects on promoting tendon-bone healing. At last, we discuss the present challenges and future research directions.

Current Therapeutic Options and Potential of Mesenchymal Stem Cell Therapy for Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a globally prevalent chronic liver disease caused by chronic or binge consumption of alcohol. The therapeutic efficiency of current therapies for ALD is limited, and there is no FDA-approved therapy for ALD at present. Various strategies targeting pathogenic events in the progression of ALD are being investigated in preclinical and clinical trials. Recently, mesenchymal stem cells (MSCs) have emerged as a promising candidate for ALD treatment and have been tested in several clinical trials. MSC-released factors have captured attention, as they have the same therapeutic function as MSCs. Herein, we focus on current therapeutic options, recently proposed strategies, and their limitations in ALD treatment. Also, we review the therapeutic effects of MSCs and those of MSC-related secretory factors on ALD. Although accumulating evidence suggests the therapeutic potential of MSCs and related factors in ALD, the mechanisms underlying their actions in ALD have not been well studied. Further investigations of the detailed mechanisms underlying the therapeutic role of MSCs in ALD are required to expand MSC therapies to clinical applications. This review provides information on current or possible treatments for ALD and contributes to our understanding of the development of effective and safe treatments for ALD.

Aging and Mesenchymal Stem Cells: Basic Concepts, Challenges and Strategies

Aging and frailty are complex processes implicating multifactorial mechanisms, such as replicative senescence, oxidative stress, mitochondrial dysfunction, or autophagy disorder. All of these mechanisms drive dramatic changes in the tissue environment, such as senescence-associated secretory phenotype factors and inflamm-aging. Thus, there is a demand for new therapeutic strategies against the devastating effects of the aging and associated diseases. Mesenchymal stem cells (MSC) participate in a "galaxy" of tissue signals (proliferative, anti-inflammatory, and antioxidative stress, and proangiogenic, antitumor, antifibrotic, and antimicrobial effects) contributing to tissue homeostasis. However, MSC are also not immune to aging. Three strategies based on MSC have been proposed: remove, rejuvenate, or replace the senescent MSC. These strategies include the use of senolytic drugs, antioxidant agents and genetic engineering, or transplantation of younger MSC. Nevertheless, these strategies may have the drawback of the adverse effects of prolonged use of the different drugs used or, where appropriate, those of cell therapy. In this review, we propose the new strategy of "Exogenous Restitution of Intercellular Signalling of Stem Cells" (ERISSC). This concept is based on the potential use of secretome from MSC, which are composed of molecules such as growth factors, cytokines, and extracellular vesicles and have the same biological effects as their parent cells. To face this cell-free regenerative therapy challenge, we have to clarify key strategy aspects, such as establishing tools that allow us a more precise diagnosis of aging frailty in order to identify the therapeutic requirements adapted to each case, identify the ideal type of MSC in the context of the functional heterogeneity of these cellular populations, to optimize the mass production and standardization of the primary materials (cells) and their secretome-derived products, to establish the appropriate methods to validate the anti-aging effects and to determine the most appropriate route of administration for each case.

Mesenchyme Stem Cell-Derived Conditioned Medium as a Potential Therapeutic Tool in Idiopathic Pulmonary Fibrosis

Mesenchyme Stem Cells (MSCs) are the most used types of stem cells in regenerative medicine. Regenerative medicine is a rapidly emerging medicine section that creates new methods to regrow, restore, and replace diseased and damaged tissues, organs, and cells. Scholars have shown a positive correlation between MSCs-based therapies and successful treatment of diseases like cardiac ischemia, cartilage problems, bone diseases, diabetes, and even neurological disorders. Although MSCs have several varying features that make them unique, their immuno-regulatory effects in tissue repair emerge from their secretion of paracrine growth factors, exosomes, and cytokines. These cells secrete a secretome, which has regenerative and reparative properties that lead to injury amelioration, immune modulation, or fibrosis reduction. Recent studies have shown that the administration MCSs derived conditioned medium (MSCs-CM) in acute doses in humans is safe and well-tolerated. Studies from animal models and human clinical trials have also shown that they are efficacious tools in regenerative medicine. In this review, we will explore the therapeutic potential of MSCs-CM in pulmonary fibrosis, with further insight into the treatment of Idiopathic Pulmonary Fibrosis (IPF).

Therapeutic effects of mesenchymal stem cells-conditioned medium derived from suspension cultivation or silymarin on liver failure mice

BACKGROUND

Common treatments of liver disease failed to meet all the needs in this important medical field. It results in an urgent need for proper some new adjuvant therapies. Mesenchymal stem cells (MSCs) and their derivatives are promising tools in this regard. We aimed to compare the Silymarin, as traditional treatment with mesenchymal stem cell conditioned medium (MSC-CM), as a novel strategy, both with therapeutic potentialities in term of liver failure (LF) treatment.

METHODS AND RESULTS

Mice models with liver failure were induced with CCl₄ and were treated in the groups as follows: normal mice receiving DMEM-LG medium as control, LF-mice receiving DMEM-LG medium as sham, LF-mice receiving Silymarin as LF-SM, and LF-mice receiving MSC sphere CM as LF-MSC-CM. Biochemical, histopathological, molecular and protein level parameters were evaluated using blood and liver samples. Liver enzymes, MicroRNA-122 values as well as necrotic score were significantly lower in the LF-SM and LF-MSC-CM groups compared to sham. LF-SM showed significantly higher level of total antioxidant capacity and malondialdehyde than that of LF-MSC-CM groups. Sph-MSC-CM not only induced more down-regulated expression of fibrinogen-like protein 1 and receptor interacting protein kinases1 but also led to higher expression level of keratinocyte growth factor. LF-MSC-CM showed less mortality rate compared to other groups.

CONCLUSIONS

Hepato-protective potentialities of Sph-MSC-CM are comparable to those of Silymarin. More inhibition of necroptosis/ necrosis and inflammation might result in rapid liver repair in case of MSC-CM administration.

Intrathecal Injection of the Secretome from ALS Motor Neurons Regulated for miR-124 Expression Prevents Disease Outcomes in SOD1-G93A Mice

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with short life expectancy and no effective therapy. We previously identified upregulated miR-124 in NSC-34-motor neurons (MNs) expressing human SOD1-G93A (mSOD1) and established its implication in mSOD1 MN degeneration and glial cell activation. When anti-miR-124-treated mSOD1 MN (preconditioned) secretome was incubated in spinal cord organotypic cultures from symptomatic mSOD1 mice, the dysregulated homeostatic balance was circumvented. To decipher the therapeutic potential of such preconditioned secretome, we intrathecally injected it in mSOD1 mice at the early stage of the disease (12-week-old). Preconditioned secretome prevented motor impairment and was effective in counteracting muscle atrophy, glial reactivity/dysfunction, and the neurodegeneration of the symptomatic mSOD1 mice. Deficits in corticospinal function and gait abnormalities were precluded, and the loss of gastrocnemius muscle fiber area was avoided. At the molecular level, the preconditioned secretome enhanced NeuN mRNA/protein expression levels and the PSD-95/TREM2/IL-10/arginase 1/MBP/PLP genes, thus avoiding the neuronal/glial cell dysregulation that characterizes ALS mice. It also prevented upregulated GFAP/Cx43/S100B/vimentin and inflammatory-associated miRNAs, specifically miR-146a/miR-155/miR-21, which are displayed by symptomatic animals. Collectively, our study highlights the intrathecal administration of the secretome from anti-miR-124-treated mSOD1 MNs as a therapeutic strategy for halting/delaying disease progression in an ALS mouse model.

PDGFRα/Sca-1 Sorted Mesenchymal Stromal Cells Reduce Liver Injury in Murine Models of Hepatic Ischemia-Reperfusion Injury

Liver transplantation is an effective therapy, but increasing demand for donor organs has led to the use of marginal donor organs with increased complication rates. Mesenchymal stromal cells (MSC) pleiotropically modulate aberrant immune-mediated responses and represent a potential therapy to target the inflammation seen post-transplant with marginal donor livers. To avoid the confounding effects of xenotransplantation seen in studies with human MSC, a PDGFRα/Sca-1 (PaS) sorted MSC population was used which was analogous to human MSC populations (LNGFR+Thy-1+VCAM-1Hi). PaS MSC are a well-described population that demonstrate MSC properties without evidence of clonal mutation during expansion. We demonstrate their anti-inflammatory properties herein through their suppression of T-lymphocyte proliferation in vitro and secretion of anti-inflammatory cytokines (IL-10 and OPG) after stimulation (P = .004 and P = .003). The MDR2-/- model of biliary injury and hepatic ischemia-reperfusion (HIR) injury models were used to replicate the non-anastomotic biliary complications seen following liver transplantation. Systemic MSC therapy in MDR2-/- mice led to reduced liver injury with an increase in restorative macrophages (5913 ± 333.9 vs 12 597 ± 665.8, P = .002, n = 7) and a change in lymphocyte ratios (3.55 ± 0.37 vs 2.59 ± 0.139, P = .023, n = 17), whereas subcutaneous administration of MSC showed no beneficial effect. MSC also reduced cell death in the HIR model assessed by Periodic acid-Schiff (PAS) staining (91.7% ± 2.8 vs 80.1% ± 4.6, P = .03). Systemically administered quantum dot-labeled MSC were tracked using single-cell resolution CryoViz imaging which demonstrated their sequestration in the lungs alongside retention/redistribution to injured liver tissue. MSC represent a potential novel therapy in marginal organ transplantation which warrants further study.

Mesenchymal (Stem) Stromal Cells Based as New Therapeutic Alternative in Inflammatory Bowel Disease: Basic Mechanisms, Experimental and Clinical Evidence, and Challenges

Inflammatory bowel diseases (IBD) are an example of chronic diseases affecting 40% of the population, which involved tissue damage and an inflammatory process not satisfactorily controlled with current therapies. Data suggest that mesenchymal stem cells (MSC) may be a therapeutic option for these processes, and especially for IBD, due to their multifactorial approaches such as anti-inflammatory, anti-oxidative stress, anti-apoptotic, anti-fibrotic, regenerative, angiogenic, anti-tumor, or anti-microbial. However, MSC therapy is associated with important limitations as safety issues, handling difficulties for therapeutic purposes, and high economic cost. MSC-derived secretome products (conditioned medium or extracellular vesicles) are therefore a therapeutic option in IBD as they exhibit similar effects to their parent cells and avoid the issues of cell therapy. In this review, we proposed further studies to choose the ideal tissue source of MSC to treat IBD, the implementation of new standardized production strategies, quality controls and the integration of other technologies, such as hydrogels, which may improve the therapeutic effects of derived-MSC secretome products in IBD.