Secretome of adipose-derived mesenchymal stem cells promotes skeletal muscle regeneration through synergistic action of extracellular vesicle cargo and soluble proteins

miRNA-21-5p is an important contributor to the promotion of injured peripheral nerve regeneration using hypoxia-pretreated bone marrow-derived neural crest cells

JOURNAL/nrgr/04.03/01300535-202501000-00035/figure1/v/2024-05-14T021156Z/r/image-tiff Our previous study found that rat bone marrow-derived neural crest cells (acting as Schwann cell progenitors) have the potential to promote long-distance nerve repair. Cell-based therapy can enhance peripheral nerve repair and regeneration through paracrine bioactive factors and intercellular communication. Nevertheless, the complex contributions of various types of soluble cytokines and extracellular vesicle cargos to the secretome remain unclear. To investigate the role of the secretome and extracellular vesicles in repairing damaged peripheral nerves, we collected conditioned culture medium from hypoxia-pretreated neural crest cells, and found that it significantly promoted the repair of sensory neurons damaged by oxygen-glucose deprivation. The mRNA expression of trophic factors was highly expressed in hypoxia-pretreated neural crest cells. We performed RNA sequencing and bioinformatics analysis and found that miR-21-5p was enriched in hypoxia-pretreated extracellular vesicles of neural crest cells. Subsequently, to further clarify the role of hypoxia-pretreated neural crest cell extracellular vesicles rich in miR-21-5p in axonal growth and regeneration of sensory neurons, we used a microfluidic axonal dissociation model of sensory neurons in vitro, and found that hypoxia-pretreated neural crest cell extracellular vesicles promoted axonal growth and regeneration of sensory neurons, which was greatly dependent on loaded miR-21-5p. Finally, we constructed a miR-21-5p-loaded neural conduit to repair the sciatic nerve defect in rats and found that the motor and sensory functions of injured rat hind limb, as well as muscle tissue morphology of the hind limbs, were obviously restored. These findings suggest that hypoxia-pretreated neural crest extracellular vesicles are natural nanoparticles rich in miRNA-21-5p. miRNA-21-5p is one of the main contributors to promoting nerve regeneration by the neural crest cell secretome. This helps to explain the mechanism of action of the secretome and extracellular vesicles of neural crest cells in repairing damaged peripheral nerves, and also promotes the application of miR-21-5p in tissue engineering regeneration medicine.

Synergistic large segmental bone repair by 3D printed bionic scaffolds and engineered ADSC nanovesicles: Towards an optimized regenerative microenvironment

Achieving sufficient bone regeneration in large segmental defects is challenging, with the structure of bone repair scaffolds and their loaded bioactive substances crucial for modulating the local osteogenic microenvironment. This study utilized digital laser processing (DLP)-based 3D printing technology to successfully fabricate high-precision methacryloylated polycaprolactone (PCLMA) bionic bone scaffold structures. Adipose-derived stem cell-engineered nanovesicles (ADSC-ENs) were uniformly and stably modified onto the bionic scaffold surface using a perfusion device, constructing a conducive microenvironment for tissue regeneration and long bone defect repair through the scaffold's structural design and the vesicles' biological functions. Scanning electron microscopy (SEM) examination of the scaffold surface confirmed the efficient loading of ADSC-ENs. The material group loaded with vesicles (PCLMA-BAS-ENs) demonstrated good cell compatibility and osteogenic potential when analyzed for the adhesion and osteogenesis of primary rabbit bone marrow mesenchymal stem cells (BMSCs) on the material surface. Tested in a 15 mm critical rabbit radial defect model, the PCLMA-BAS-ENs scaffold facilitated near-complete bone defect repair after 12 weeks. Immunofluorescence and proteomic results indicated that the PCLMA-BAS-ENs scaffold significantly improved the osteogenic microenvironment at the defect site in vivo, promoted angiogenesis, and enhanced the polarization of macrophages towards M2 phenotype, and facilitated the recruitment of BMSCs. Thus, the PCLMA-BAS-ENs scaffold was proven to significantly promote the repair of large segmental bone defects. Overall, this strategy of combining engineered vesicles with highly biomimetic scaffolds to promote large-segment bone tissue regeneration holds great potential in orthopedic and other regenerative medicine applications.

Mass spectrometry for the study of adipocyte cell secretome in cardiovascular diseases

Adipose tissue is classically considered the primary site of lipid storage, but in recent years has garnered appreciation for its broad role as an endocrine organ, capable of remotely signaling to other tissues to alter their metabolic program. The adipose tissue is now recognized as a crucial regulator of cardiovascular health, mediated by the secretion of several bioactive products, with a wide range of endocrine and paracrine effects on the cardiovascular system. Thanks to the development and improvement of high-throughput mass spectrometry, the size and components of the human secretome have been characterized. In this review, we summarized the recent advances in mass spectrometry-based studies of the cell and tissue secretome for the understanding of adipose tissue biology, which may help to decipher the complex molecular mechanisms controlling the crosstalk between the adipose tissue and the cardiovascular system, and their possible clinical translation.

Pluronic F127 composite hydrogel for the repair of contraction suppressed full-thickness skin wounds in a rabbit model

Hydrogels are commonly used as carriers for cell delivery due to their similarities to the extracellular matrix. A contraction-suppressed full-thickness wound model was used to evaluate the therapeutic potential of Pluronic F127 (PF127) hydrogel loaded with adipose-derived stromal vascular fraction (AdSVF), mesenchymal stem cells (AdMSC), and conditioned media (AdMSC-CM) for the repair of wounds in a rabbit model. The experimental study was conducted on forty-eight healthy adult New Zealand white rabbits randomly divided into eight groups with six animals each and treated with AdSVF, AdMSC, and AdMSC-CM as an injectable or topical preparation. The healing potential of different adipose-derived cell-based and cell-free therapeutics was evaluated based on percentage wound healing, period of epithelialization, epidermal thickness, scar evaluation, histopathology analysis, histochemical evaluation, immunohistochemistry (collagen type I), and hydroxyproline assay by comparing with the positive and negative control. Collagen density analysis using different staining methods, immunohistochemistry, and hydroxyproline assay consistently showed that delivering AdMSC and AdMSC-CM in PF127 hydrogel enhanced epithelialization, collagen production, and organization, contributing to improved tissue strength and quality. Even though allogeneic AdSVF was found to promote wound healing in rabbits, it has a lower potential than AdMSC and AdMSC-CM. The wound healing potential of AdMSC and AdMSC-CM was enhanced when loaded in PF127 hydrogel and applied topically. Even though wounds treated with AdMSC outperformed AdMSC-CM, a significant difference in the healing quality was not observed in most instances, indicating almost similar therapeutic potential. The findings indicate that the wound healing potential of AdMSC and AdMSC-CM was enhanced when loaded in PF127 hydrogel and applied topically. These treatments promoted collagen production, tissue organization, and epidermal regeneration, ultimately improving overall healing outcomes.

Motion-Accommodating Dual-Layer Hydrogel Dressing to Deliver Adipose-Derived Stem Cells to Wounds

BACKGROUND

Current dressing materials cannot secure a cell survival-promoting wound environment for stem cell delivery due to insufficient assimilation to skin motion. The authors developed a novel motion-accommodating dual-layer hydrogel dressing for stem cell delivery into such wounds.

METHODS

Dorsal hand skin movement was evaluated to determine the potential range of deformation for a dressing. The outer hydrogel (OH) was fabricated with an alginate-acrylamide double-network hydrogel with a covalently cross-linked elastomer coat. The tough adhesive consisted of a chitosan-based bridging polymer and coupling reagents. OH material properties and adhesiveness on porcine skin were measured. An oxidized alginate-based inner hydrogel (IH) containing human adipose-derived stem cells (ASCs) was evaluated for cell-supporting and cell-releasing properties. The OH's function as a secondary dressing, and dual-layer hydrogel cell delivery potential in wounds were assessed in a rodent model.

RESULTS

The dual-layer hydrogel consisted of OH and IH. The OH target range of deformation was up to 25% strain. The OH adhered to porcine skin, and showed significantly higher adhesion energy than common secondary dressings and endured 900 flexion-extension cycles without detachment. OH showed a similar moisture vapor transmission rate as moisture-retentive dressings. IH maintained embedded cell survival for three days with significant cell release on the contacting surface. OH showed less fibrotic wound healing than other secondary dressings in vivo. The dual-layer hydrogel successfully delivered ASCs into open wounds of nude mice (13 ± 3 cells/HPF).

CONCLUSIONS

The novel dual-layer hydrogel can accommodate patient movement and deliver ASCs into the wound bed by securing the wound microenvironment.

Clinical Applications of Adipose-Derived Stem Cell (ADSC) Exosomes in Tissue Regeneration

Adipose-derived stem cells (ADSCs) are mesenchymal stem cells with a great potential for self-renewal and differentiation. Exosomes derived from ADSCs (ADSC-exos) can imitate their functions, carrying cargoes of bioactive molecules that may affect specific cellular targets and signaling processes. Recent evidence has shown that ADSC-exos can mediate tissue regeneration through the regulation of the inflammatory response, enhancement of cell proliferation, and induction of angiogenesis. At the same time, they may promote wound healing as well as the remodeling of the extracellular matrix. In combination with scaffolds, they present the future of cell-free therapies and promising adjuncts to reconstructive surgery with diverse tissue-specific functions and minimal adverse effects. In this review, we address the main characteristics and functional properties of ADSC-exos in tissue regeneration and explore their most recent clinical application in wound healing, musculoskeletal regeneration, dermatology, and plastic surgery as well as in tissue engineering.

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.

Therapeutic potential of RNA-enriched extracellular vesicles: The next generation in RNA delivery via biogenic nanoparticles

Exosomes are extracellular vesicles (EVs) (∼50-150 nm) that have emerged as promising vehicles for therapeutic applications and drug delivery. These membrane-bound particles, released by all actively dividing cells, have the ability to transfer effector molecules, including proteins, RNA, and even DNA, from donor cells to recipient cells, thereby modulating cellular responses. RNA-based therapeutics, including microRNAs, messenger RNAs, long non-coding RNAs, and circular RNAs, hold great potential in controlling gene expression and treating a spectrum of medical conditions. RNAs encapsulated in EVs are protected from extracellular degradation, making them attractive for therapeutic applications. Understanding the intricate biology of cargo loading and transfer within EVs is pivotal to unlocking their therapeutic potential. This review discusses the biogenesis and classification of EVs, methods for loading RNA into EVs, their advantages as drug carriers over synthetic-lipid-based systems, and the potential applications in treating neurodegenerative diseases, cancer, and viral infections. Notably, EVs show promise in delivering RNA cargo across the blood-brain barrier and targeting tumor cells, offering a safe and effective approach to RNA-based therapy in these contexts.

Muscle stem cells as immunomodulator during regeneration

The skeletal muscle is well known for its remarkable ability to regenerate after injuries. The regeneration is a complex and dynamic process that involves muscle stem cells (also called muscle satellite cells, MuSCs), fibro-adipogenic progenitors (FAPs), immune cells, and other muscle-resident cell populations. The MuSCs are the myogenic cell populaiton that contribute nuclei directly to the regenerated myofibers, while the other cell types collaboratively establish a microenvironment that facilitates myogenesis of MuSCs. The myogenic process includes activation, proliferation and differentiationof MuSCs, and subsequent fusion their descendent mononuclear myocytes into multinuclear myotubes. While the contributions of FAPs and immune cells to this microenvironment have been well studied, the influence of MuSCs on other cell types remains poorly understood. This review explores recent evidence supporting the potential role of MuSCs as immunomodulators during muscle regeneration, either through cytokine production or ligand-receptor interactions.

Adipose Mesenchymal Stem Cell Metabolites Oral Gel Enhance Pro-Angiogenic Factors Expression, Angiogenesis, and Clinical Outcome of Oral Ulcer Rat Model

OBJECTIVE

 Enhancing wound healing capacity is one of the main principles in oral ulcer management. Efficient oral ulcer management will accelerate clinical symptom amelioration and prevent complications. Adipose mesenchymal stem cell metabolites (AdMSCM), a novel biological product, contains a plethora of bioactive mediators that can induce a series of processes in wound healing. This study will analyze the clinical outcome, angiogenesis, and expression of FGF-2 and VEGFA in the oral ulcer rat model after AdMSCM oral gel application.

MATERIALS AND METHODS

 Twenty healthy male Wistar rats (Rattus novergicus) were used to create oral ulcer animal models. AdMSCM oral gel treatment was performed three times daily for 3 and 7 days. Clinical outcome was assessed by measuring the major diameter of the ulcer; the angiogenesis was evaluated through histological assessment; the expression of VEGFA and FGF-2 was assessed using the immunohistochemistry method.

STATISTICAL ANALYSIS

 This study uses parametric comparative analysis using one-way analysis of variance (ANOVA) and post-hoc Tukey's HSD test RESULTS:  The application of AdMSCM oral gel in an oral ulcer rat model significantly enhanced the clinical outcome (p < 0.05). In addition, similar results were shown in the histologic assessment of angiogenesis and supported by the significant increase of VEGFA and FGF-2 expression.

CONCLUSIONS

 AdMSCM oral gel accelerates oral ulcer healing processes, proven by the enhancement of angiogenesis, pro-angiogenic factors expression, and clinical outcomes.

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.

Treatment of type 2 diabetes mellitus with stem cells and antidiabetic drugs: a dualistic and future-focused approach

Type 2 Diabetes Mellitus (T2DM) accounts for more than 90% of total diabetes mellitus cases all over the world. Obesity and lack of balance between energy intake and energy expenditure are closely linked to T2DM. Initial pharmaceutical treatment and lifestyle interventions can at times lead to remission but usually help alleviate it to a certain extent and the condition remains, thus, recurrent with the patient being permanently pharmaco-dependent. Mesenchymal stromal cells (MSCs) are multipotent, self-renewing cells with the ability to secrete a variety of biological factors that can help restore and repair injured tissues. MSC-derived exosomes possess these properties of the original stem cells and are potentially able to confer superior effects due to advanced cell-to-cell signaling and the presence of stem cell-specific miRNAs. On the other hand, the repository of antidiabetic agents is constantly updated with novel T2DM disease-modifying drugs, with higher efficacy and increasingly convenient delivery protocols. Delving deeply, this review details the latest progress and ongoing studies related to the amalgamation of stem cells and antidiabetic drugs, establishing how this harmonized approach can exert superior effects in the management and potential reversal of T2DM.

Recent advances of exosomes in soft tissue injuries in sports medicine: A critical review on biological and biomaterial applications

Sports medicine is generally associated with soft tissue injuries including muscle injuries, meniscus and ligament injuries, tendon ruptures, tendinopathy, rotator cuff tears, and tendon-bone healing during injuries. Tendon and ligament injuries are the most common sport injuries accounting for 30-40% of all injuries. Therapies for tendon injuries can be divided into surgical and non-surgical methods. Surgical methods mainly depend on the operative procedures, the surgeons and postoperative interventions. In non-surgical methods, cell therapy with stem cells and cell-free therapy with secretome of stem cell origin are current directions. Exosomes are the main paracrine factors of mesenchymal stem cells (MSCs) containing biological components such as proteins, nucleic acids and lipids. Compared with MSCs, MSC-exosomes (MSC-exos) possess the capacity to escape phagocytosis and achieve long-term circulation. In addition, the functions of exosomes from various cell sources in soft tissue injuries in sports medicine have been gradually revealed in recent years. Along with the biological and biomaterial advances in exosomes, exosomes can be designed as drug carriers with biomaterials and exosome research is providing promising contributions in cell biology. Exosomes with biomaterial have the potential of becoming one of the novel therapeutic modalities in regenerative researches. This review summarizes the derives of exosomes in soft tissue regeneration and focuses on the biological and biomaterial mechanism and advances in exosomal therapy in soft tissue injuries.

Extracellular vesicles derived from human ESC-MSCs target macrophage and promote anti-inflammation process, angiogenesis, and functional recovery in ACS-induced severe skeletal muscle injury

BACKGROUND

Acute compartment syndrome (ACS) is one of the most common complications of musculoskeletal injury, leading to the necrosis and demise of skeletal muscle cells. Our previous study showed that embryonic stem cells-derived mesenchymal stem cells (ESC-MSCs) are novel therapeutics in ACS treatment. As extracellular vesicles (EVs) are rapidly gaining attention as cell-free therapeutics that have advantages over parental stem cells, the therapeutic potential and mechanisms of EVs from ESC-MSCs on ACS need to be explored.

METHOD

In the present study, we examined the protective effects in the experimental ACS rat model and investigated the role of macrophages in mediating these effects. Next, we used transcriptome sequencing to explore the mechanisms by which ESC-MSC-EVs regulate macrophage polarization. Furthermore, miRNA sequencing was performed on ESC-MSC-EVs to identify miRNA candidates associated with macrophage polarization.

RESULTS

We found that intravenous administration of ESC-MSC-EVs, given at the time of fasciotomy, significantly promotes the anti-inflammation process, angiogenesis, and functional recovery of muscle in ACS. The beneficial effects were associated with ESC-MSC-EVs affecting macrophage polarization by delivering various miRNAs which regulate NF-κB, JAK/STAT, and PI3K/AKT pathways. Our data further illustrate that ESC-MSC-EVs mainly modulate macrophage polarization via the miR-21/PTEN, miR-320a/PTEN, miR-423/NLRP3, miR-100/mTOR, and miR-26a/TLR3 axes.

CONCLUSION

Together, our results demonstrated the beneficial effects of ESC-MSC-EVs in ACS, wherein the miRNAs present in ESC-MSC-EVs regulate the polarization of macrophages.

ADSC secretome constrains NK cell activity by attenuating IL-2-mediated JAK-STAT and AKT signaling pathway via upregulation of CIS and DUSP4

BACKGROUND

Mesenchymal stem cells (MSCs) have immunomodulatory properties and therapeutic effects on autoimmune diseases through their secreted factors, referred to as the secretome. However, the specific key factors of the MSC secretome and their mechanisms of action in immune cells have not been fully determined. Most in vitro experiments are being performed using immune cells, but experiments using natural killer (NK) cells have been neglected, and a few studies using NK cells have shown discrepancies in results. NK cells are crucial elements of the immune system, and adjustment of their activity is essential for controlling various pathological conditions. The aim of this study was to elucidate the role of the adipose tissue-derived stem cell (ADSC) secretome on NK cell activity.

METHODS

To obtain the ADSC secretome, we cultured ADSCs in medium and concentrated the culture medium using tangential flow filtration (TFF) capsules. We assessed NK cell viability and proliferation using CCK-8 and CFSE assays, respectively. We analyzed the effects of the ADSC secretome on NK cell activity and pathway-related proteins using a combination of flow cytometry, ELISA, cytotoxicity assay, CD107a assay, western blotting, and quantitative real-time PCR. To identify the composition of the ADSC secretome, we performed LC-MS/MS profiling and bioinformatics analysis. To elucidate the molecular mechanisms involved, we used mRNA sequencing to profile the transcriptional expression of human blood NK cells.

RESULTS

The ADSC secretome was found to restrict IL-2-mediated effector function of NK cells while maintaining proliferative potency. This effect was achieved through the upregulation of the inhibitory receptor CD96, as well as downregulation of activating receptors and IL-2 receptor subunits IL-2Rα and IL-2Rγ. These changes were associated with attenuated JAK-STAT and AKT pathways in NK cells, which were achieved through the upregulation of cytokine-inducible SH2-containing protein (CIS, encoded by Cish) and dual specificity protein phosphatase 4 (DUSP4). Furthermore, proteomic analysis revealed twelve novel candidates associated with the immunomodulatory effects of MSCs.

CONCLUSIONS

Our findings reveal a detailed cellular outcome and regulatory mechanism of NK cell activity by the ADSC secretome and suggest a therapeutic tool for treating NK-mediated inflammatory and autoimmune diseases using the MSC secretome.

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.

Comprehensive Analysis of Local Anesthetics Affecting Adipose Stem Cells In Vitro

BACKGROUND

Adipose stem cells (ASCs) hold a great regenerative capacity because of their differentiation capability and their secretory activity. Thus, ASC survival is of great significance during perioperative harvesting. Various local anesthetics are commonly applied during fat grafting procedures. These substances are known to impair cellular viability, which would affect graft survival and final outcomes, but the exact extent of their impact on ASC biology is unknown.

METHODS

The authors analyzed the short- and long-term effects of lidocaine, mepivacaine, ropivacaine, and bupivacaine at increasing concentrations (0.1 to 10 mM) on primary human ASC proliferation and metabolic activity. Trilinear differentiation was assessed by oil red O stain (adipogenesis), safranin O (chondrogenesis), and cresolphthalein (osteogenesis) labeling. In supernatants, cytokine [interleukin (IL)-6/IL-8, vascular endothelial growth factor, hepatocyte growth factor] secretion was analyzed by enzyme-linked immunosorbent assay.

RESULTS

Bupivacaine at greater than 100 µM demonstrated the strongest anti proliferative effects, whereas lidocaine and ropivacaine did not affect cell numbers. Mepivacaine evoked reciprocal results regarding cell count at greater than 1 mM. Each compound impaired trilinear differentiation. Secretion of hepatocyte growth factor and IL-8 was reduced significantly by local anesthetic exposure; levels were restored after substances were washed out.

CONCLUSIONS

In vitro data show that lidocaine, mepivacaine, and ropivacaine could be applied at concentrations of 1 to 10 mM without affecting ASC survival. In contrast, bupivacaine at concentrations greater than 100 µM should be administered with great caution. The differentiation of ASCs and the ASC's secretome might already be decreased by each local anesthetic at 1 mM.

CLINICAL RELEVANCE STATEMENT

The authors' experimental data can be of great significance to the clinical practice, as local anesthetics are routinely administered during liposuction as a tumescent anesthesia adjunct.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Arsenic disrupts extracellular vesicle-mediated signaling in regenerating myofibers

Chronic exposure to environmental arsenic is a public health crisis affecting hundreds of millions of individuals worldwide. Though arsenic is known to contribute to many pathologies and diseases, including cancers, cardiovascular and pulmonary diseases, and neurological impairment, the mechanisms for arsenic-promoted disease remain unresolved. This is especially true for arsenic impacts on skeletal muscle function and metabolism, despite the crucial role that skeletal muscle health plays in maintaining cardiovascular health, systemic homeostasis, and cognition. A barrier to researching this area is the challenge of interrogating muscle cell-specific effects in biologically relevant models. Ex vivo studies investigating mechanisms for muscle-specific responses to arsenic or other environmental contaminants primarily utilize traditional 2-dimensional culture models that cannot elucidate effects on muscle physiology or function. Therefore, we developed a contractile 3-dimensional muscle construct model-composed of primary mouse muscle progenitor cells differentiated in a hydrogel matrix-to study arsenic exposure impacts on skeletal muscle regeneration. Muscle constructs exposed to low-dose (50 nM) arsenic exhibited reduced strength and myofiber diameter following recovery from muscle injury. These effects were attributable to dysfunctional paracrine signaling mediated by extracellular vesicles (EVs) released from muscle cells. Specifically, we found that EVs collected from arsenic-exposed muscle constructs recapitulated the inhibitory effects of direct arsenic exposure on myofiber regeneration. In addition, muscle constructs treated with EVs isolated from muscles of arsenic-exposed mice displayed significantly decreased strength. Our findings highlight a novel model for muscle toxicity research and uncover a mechanism of arsenic-induced muscle dysfunction by the disruption of EV-mediated intercellular communication.

Anti-inflammatory effect of interleukin-6 highly enriched in secretome of two clinically relevant sources of mesenchymal stromal cells

Despite several advances in the field of regenerative medicine, clinical management of extensive skin wounds or burns remains a major therapeutic issue. During the past few years, Mesenchymal Stromal Cells (MSCs) have emerged as a novel therapeutic tool to promote tissue repair through their anti-inflammatory, pro-trophic and pro-remodeling effects. They exert their biological activity mainly via the secretion of soluble bioactive molecules such as cytokines, growth factors, proteins and microRNAs which can be encapsulated within extracellular vesicles (EV). The recent discovery of their high plasticity to external stimuli has fostered the development of new targeted therapies known as priming strategies, to enhance their potential. Our team recently showed that Interleukin-1β (IL-1β)-primed gingival MSCs promote wound healing and epidermal engraftment in vitro, and in vivo through their secreted products that contain extracellular vesicles. In the present work, we investigated whether two common sources of MSCs, gingiva and bone marrow, could respond similarly to IL-1β to favor pro-healing capabilities of their secretome. We showed that both primed-MSC sources, or their related secreted products, are able to reduce inflammation in LPS-challenged human monocytic THP-1 cell line. IL-1β priming enhanced MSC secretion of wound healing-related growth factors, cytokines and miRNAs in both sources. Among them, interleukin 6 was shown to be involved in the anti-inflammatory effect of MSC secreted products. Overall, these results underline the pro-healing properties of both MSC sources and their secretome upon IL-1β priming and their potential to improve the current medical treatment of severe wounds.

Mesenchymal Stem Cells in Soft Tissue Regenerative Medicine: A Comprehensive Review

Soft tissue regeneration holds significant promise for addressing various clinical challenges, ranging from craniofacial and oral tissue defects to blood vessels, muscle, and fibrous tissue regeneration. Mesenchymal stem cells (MSCs) have emerged as a promising tool in regenerative medicine due to their unique characteristics and potential to differentiate into multiple cell lineages. This comprehensive review explores the role of MSCs in different aspects of soft tissue regeneration, including their application in craniofacial and oral soft tissue regeneration, nerve regeneration, blood vessel regeneration, muscle regeneration, and fibrous tissue regeneration. By examining the latest research findings and clinical advancements, this article aims to provide insights into the current state of MSC-based therapies in soft tissue regenerative medicine.

Mesenchymal stem cells alleviate dexamethasone-induced muscle atrophy in mice and the involvement of ERK1/2 signalling pathway

BACKGROUND

High dosage of dexamethasone (Dex) is an effective treatment for multiple diseases; however, it is often associated with severe side effects including muscle atrophy, resulting in higher risk of falls and poorer life quality of patients. Cell therapy with mesenchymal stem cells (MSCs) holds promise for regenerative medicine. In this study, we aimed to investigate the therapeutic efficacy of systemic administration of adipose-derived mesenchymal stem cells (ADSCs) in mitigating the loss of muscle mass and strength in mouse model of DEX-induced muscle atrophy.

METHODS

3-month-old female C57BL/6 mice were treated with Dex (20 mg/kg body weight, i.p.) for 10 days to induce muscle atrophy, then subjected to intravenous injection of a single dose of ADSCs ([Formula: see text] cells/kg body weight) or vehicle control. The mice were killed 7 days after ADSCs treatment. Body compositions were measured by animal DXA, gastrocnemius muscle was isolated for ex vivo muscle functional test, histological assessment and Western blot, while tibialis anterior muscles were isolated for RNA-sequencing and qPCR. For in vitro study, C2C12 myoblast cells were cultured under myogenic differentiation medium for 5 days following 100 [Formula: see text]M Dex treatment with or without ADSC-conditioned medium for another 4 days. Samples were collected for qPCR analysis and Western blot analysis. Myotube morphology was measured by myosin heavy chain immunofluorescence staining.

RESULTS

ADSC treatment significantly increased body lean mass (10-20%), muscle wet weight (15-30%) and cross-sectional area (CSA) (~ 33%) in DEX-induced muscle atrophy mice model and down-regulated muscle atrophy-associated genes expression (45-65%). Hindlimb grip strength (~ 37%) and forelimb ex vivo muscle contraction property were significantly improved (~ 57%) in the treatment group. Significant increase in type I fibres (~ 77%) was found after ADSC injection. RNA-sequencing results suggested that ERK1/2 signalling pathway might be playing important role underlying the beneficial effect of ADSC treatment, which was confirmed by ERK1/2 inhibitor both in vitro and in vivo.

CONCLUSIONS

ADSCs restore the pathogenesis of Dex-induced muscle atrophy with an increased number of type I fibres, stronger muscle strength, faster recovery rate and more anti-fatigue ability via ERK1/2 signalling pathway. The inhibition of muscle atrophy-associated genes by ADSCs offered this treatment as an intervention option for muscle-associated diseases. Taken together, our findings suggested that adipose-derived mesenchymal stem cell therapy could be a new treatment option for patient with Dex-induced muscle atrophy.

Mesenchymal Stem Cell Conditioned Medium Modulates Inflammation in Tenocytes: Complete Conditioned Medium Has Superior Therapeutic Efficacy than Its Extracellular Vesicle Fraction

Tendinopathy, a prevalent overuse injury, lacks effective treatment options, leading to a significant impact on quality of life and socioeconomic burden. Mesenchymal stem/stromal cells (MSCs) and their secretome, including conditioned medium (CM) and extracellular vesicles (EVs), have shown promise in tissue regeneration and immunomodulation. However, it remains unclear which components of the secretome contribute to their therapeutic effects. This study aimed to compare the efficacy of CM, EVs, and the soluble protein fraction (PF) in treating inflamed tenocytes. CM exhibited the highest protein and particle concentrations, followed by PF and EVs. Inflammation significantly altered gene expression in tenocytes, with CM showing the most distinct separation from the inflamed control group. Treatment with CM resulted in the most significant differential gene expression, with both upregulated and downregulated genes related to inflammation and tissue regeneration. EV treatment also demonstrated a therapeutic effect, albeit to a lesser extent. These findings suggest that CM holds superior therapeutic efficacy compared with its EV fraction alone, emphasizing the importance of the complete secretome in tendon injury treatment.

Construction of tissue-engineered bladders using an artificial acellular nanocomposite scaffold loaded with stromal vascular fraction secretome

Tissue engineering approaches offer promising alternative strategies for reconstructing bladder tissue; however, the low retention of transplanted cells and the possible risk of rejection limit their therapeutic efficacy. Clinical applicability is further limited by the lack of suitable scaffold materials to support the needs of various cell types. In the present study, we developed an artificial nanoscaffold system consisting of stromal vascular fraction (SVF) secretome (Sec) loaded onto zeolitic imidazolate framework-8 (ZIF-8) nanoparticles, which were then incorporated into bladder acellular matrix. This artificial acellular nanocomposite scaffold (ANS) can achieve gradient degradation and slowly release SVF-Sec to promote tissue regeneration. Furthermore, even after long-term cryopreservation, this completely acellular bladder nanoscaffold material still maintains its efficacy. In a rat bladder replacement model, ANS transplantation demonstrated potent proangiogenic ability and induced M2 macrophage polarization to promote tissue regeneration and restore bladder function. Our study demonstrates the safety and efficacy of the ANS, which can play a stem cell-like role while avoiding the disadvantages of cell therapy. Furthermore, the ANS can replace the bladder regeneration model based on cell-binding scaffold materials and has the potential for clinical application. STATEMENT OF SIGNIFICANCE: This study aimed to develop a gradient-degradable artificial acellular nanocomposite scaffold (ANS) loaded with stromal vascular fraction (SVF) secretome for rehabilitating bladders. Using various in vitro methods as well as rat- and zebrafish-based in vivo models, the developed ANS was assessed for efficacy and safety. Results indicated that the ANS achieved gradient degradation and slowly released the SVF secretome to promote tissue regeneration, even after long-term cryopreservation. Furthermore, ANS transplantation demonstrated a potent pro-angiogenic ability and induced M2 macrophage polarization to promote tissue regeneration and restore bladder function in a bladder replacement model. Our study demonstrates that ANS may replace bladder regeneration models based on cell-binding scaffold materials and have potential clinical application.

Decreased CRISPLD2 expression impairs osteogenic differentiation of human mesenchymal stem cells during in vitro expansion

Human mesenchymal stem cells (hMSCs) are the cornerstone of regenerative medicine; large quantities of hMSCs are required via in vitro expansion to meet therapeutic purposes. However, hMSCs quickly lose their osteogenic differentiation potential during in vitro expansion, which is a major roadblock to their clinical applications. In this study, we found that the osteogenic differentiation potential of human bone marrow stem cells (hBMSCs), dental pulp stem cells (hDPSCs), and adipose stem cells (hASCs) was severely impaired after in vitro expansion. To clarify the molecular mechanism underlying this in vitro expansion-related loss of osteogenic capacity in hMSCs, the transcriptome changes following in vitro expansion of these hMSCs were compared. Cysteine-rich secretory protein LCCL domain-containing 2 (CRISPLD2) was identified as the most downregulated gene shared by late passage hBMSCs, hDPSCs, and hASCs. Both the secreted and non-secreted CRISPLD2 proteins progressively declined in hMSCs during in vitro expansion when the cells gradually lost their osteogenic potential. We thus hypothesized that the expression of CRISPLD2 is critical for hMSCs to maintain their osteogenic differentiation potential during in vitro expansion. Our studies showed that the knockdown of CRISPLD2 in early passage hBMSCs inhibited the cells' osteogenic differentiation in a siRNA dose-dependent manner. Transcriptome analysis and immunoblotting indicated that the CRISPLD2 knockdown-induced osteogenesis suppression might be attributed to the downregulation of matrix metallopeptidase 1 (MMP1) and forkhead box Q1 (FOXQ1). Furthermore, adeno-associated virus (AAV)-mediated CRISPLD2 overexpression could somewhat rescue the impaired osteogenic differentiation of hBMSCs during in vitro expansion. These results revealed that the downregulation of CRISPLD2 contributes to the impaired osteogenic differentiation of hMSCs during in vitro expansion. Our findings shed light on understanding the loss of osteogenic differentiation in hMSCs and provide a potential therapeutic target gene for bone-related diseases.

Outlook of Adipose-Derived Stem Cells: Challenges to Their Clinical Application in Horses

Adipose tissue is recognized as the major endocrine organ, potentially acting as a source of mesenchymal stem cells for various applications in regenerative medicine. Athletic horses are often exposed to traumatic injuries, resulting in severe financial losses. The development of adipose-derived stem cells' regenerative potential depends on many factors. The extraction of stem cells from subcutaneous adipose tissue is non-invasive, non-traumatic, cheaper, and safer than other sources. Since there is a lack of unique standards for identification, the isolated cells and applied differentiation protocols are often not species-specific; therefore, the cells cannot reveal their multipotent properties, so their stemness features remain questionable. The current review discusses some aspects of the specificity of equine adipose stem cells concerning their features, immunophenotyping, secretome profile, differentiation abilities, culturing conditions, and consequent possibilities for clinical application in concrete disorders. The presented new approaches elucidate the possibility of the transition from cell-based to cell-free therapy with regenerative purposes in horses as an alternative treatment to cellular therapy. In conclusion, their clinical benefits should not be underestimated due to the higher yield and the physiological properties of adipose-derived stem cells that facilitate the healing and tissue regeneration process and the ability to amplify the effects of traditional treatments. More profound studies are necessary to apply these innovative approaches when treating traumatic disorders in racing horses.

Uncovering the gray zone: mapping the global landscape of direct-to-consumer businesses offering interventions based on secretomes, extracellular vesicles, and exosomes

BACKGROUND

The last decade has seen a significant increase in media attention, industrial growth, and patient interest in stem cell-based interventions. This led to a rise in direct-to-consumer businesses offering stem cell "therapies" for multiple indications with little evidence of safety and efficacy. In parallel, the use of stem cell secretomes as a substitute for stem cell transplantation has become an increasing trend in regenerative medicine with multiple clinical trials currently assessing their efficacy and safety profile. As a result, multiple businesses and private clinics have now started to exploit this situation and are offering secretome-based interventions despite the lack of supporting data. This poses significant risks for the patients and could lead to a credibility crisis in the field.

METHODS

Internet searches were used to locate clinics marketing and selling interventions based on stem cell secretomes, exosomes, or extracellular vesicles. Data were extracted from websites with a particular focus on the global distribution of the businesses, the cellular source of the secretome, the indication spectrum, and the pricing of the provided services. Lastly, the types of evidence used on the websites of the businesses to market their services were extracted.

RESULTS

Overall, 114 companies market secretome-based therapies in 28 countries. The vast majority of the interventions are based on allogenic stem cells from undisclosed cellular sources and skin care is the most marketed indication. The price range is USD99-20,000 depending on the indication.

CONCLUSIONS

The direct-to-consumer industry for secretome-based therapies appears to be primed for growth in the absence of appropriate regulatory frameworks and guidelines. We conclude that such business activity requires tight regulations and monitoring by the respective national regulatory bodies to prevent patients from being conned and more importantly from being put at risk.

Adipose Tissue-Derived Stem Cell Extracellular Vesicles Suppress Glioblastoma Proliferation, Invasiveness and Angiogenesis

Extracellular vesicles (EVs) are attractive anticancer drug delivery candidates as they confer several fundamental properties, such as low immunogenicity and the ability to cross biological barriers. Mesenchymal stem cells (MSCs) are convenient producers for high EV yields, and patient-derived adipose tissue MSC-EVs could serve as personalised carriers. However, MSC-EV applications raise critical concerns as their natural cargo can affect tumour progression in both inducing and suppressing ways. In this study, we investigated the effect of adipose tissue-derived mesenchymal stem cell EVs (ASC-EVs) on several glioblastoma (GBM) cell lines to define their applicability for anticancer therapies. ASC-EVs were isolated from a cell-conditioned medium and characterised by size and specific markers. The internalisation of fluorescently labelled ASC-EVs by human GBM cells HROG36, U87 MG, and T98G was evaluated by fluorescent microscopy. Changes in GBM cell proliferation after ASC-EV application were determined by the metabolic PrestoBlue assay. Expression alterations in genes responsible for cell adhesion, proliferation, migration, and angiogenesis were evaluated by quantitative real-time PCR. ASC-EV effects on tumour invasiveness and neoangiogenesis in ovo were analysed on the chicken embryo chorioallantoic membrane model (CAM). ASC-EV treatment reduced GBM proliferation in vitro and significantly downregulated invasiveness-related genes ITGα5 (in T98G and HROG63) and ITGβ3 (in HROG36) and the vascularisation-inducing gene KDR (in all GBM lines). Additionally, an approximate 65% reduction in the GBM invasion rate was observed in CAM after ASC-EV treatment. Our study indicates that ASC-EVs possess antitumour properties, reducing GBM cell proliferation and invasiveness, and can be applied as anticancer therapeutics and medicine carriers.

Regulatory Effects of Three-Dimensional Cultured Lipopolysaccharide-Pretreated Periodontal Ligament Stem Cell-Derived Secretome on Macrophages

Phenotypic transformation of macrophages plays important immune response roles in the occurrence, development and regression of periodontitis. Under inflammation or other environmental stimulation, mesenchymal stem cells (MSCs) exert immunomodulatory effects through their secretome. It has been found that secretome derived from lipopolysaccharide (LPS)-pretreated or three-dimensional (3D)-cultured MSCs significantly reduced inflammatory responses in inflammatory diseases, including periodontitis, by inducing M2 macrophage polarization. In this study, periodontal ligament stem cells (PDLSCs) pretreated with LPS were 3D cultured in hydrogel (termed SupraGel) for a certain period of time and the secretome was collected to explore its regulatory effects on macrophages. Expression changes of immune cytokines in the secretome were also examined to speculate on the regulatory mechanisms in macrophages. The results indicated that PDLSCs showed good viability in SupraGel and could be separated from the gel by adding PBS and centrifuging. The secretome derived from LPS-pretreated and/or 3D-cultured PDLSCs all inhibited the polarization of M1 macrophages, while the secretome derived from LPS-pretreated PDLSCs (regardless of 3D culture) had the ability to promote the polarization of M1 to M2 macrophages and the migration of macrophages. Cytokines involved in the production, migration and polarization of macrophages, as well as multiple growth factors, increased in the PDLSC-derived secretome after LPS pretreatment and/or 3D culture, which suggested that the secretome had the potential to regulate macrophages and promote tissue regeneration, and that it could be used in the treatment of inflammation-related diseases such as periodontitis in the future.

Exosomes from adipose-derived stem cells promote angiogenesis and reduce necrotic grade in hindlimb ischemia mouse models

Objectives

Acute hindlimb ischemia is a peripheral arterial disease that severely affects the patient's health. Injection of stem cells-derived exosomes that promote angiogenesis is a promising therapeutic strategy to increase perfusion and repair ischemic tissues. This study aimed to evaluate the efficacy of adipose stem cell-derived exosomes injection (ADSC-Exos) in treating acute mouse hindlimb ischemia.

Materials and Methods

ADSC-Exos were collected via ultracentrifugation. Exosome-specific markers were analyzed via flow cytometry. The morphology of exosomes was detected by TEM. A dose of 100 ug exosomes/100 ul PBS was locally injected into acute mice ischemic hindlimb. The treatment efficacy was evaluated based on the oxygen saturation level, limb function, new blood vessel formation, muscle structure recovery, and limb necrosis grade.

Results

ADSC-exosomes expressed high positivity for markers CD9 (76.0%), CD63 (91.2%), and CD81 (99.6%), and have a cup shape. After being injected into the muscle, in the treatment group, many small and short blood vessels formed around the first ligation and grew down toward the second ligation. The SpO2 level, reperfusion, and recovery of the limb function are more positively improved in the treatment group. On day 28, the muscle's histological structure in the treatment group is similar to normal tissue. Approximately 33.33% of the mice had grade I and II lesions and there were no grade III and IV observed in the treatment group. Meanwhile, in the placebo group, 60% had grade I to IV lesions.

Conclusion

ADSC-Exos showed the ability to stimulate angiogenesis and significantly reduce the rate of limb necrosis.

Soluble components from mesenchymal stromal cell processing exert anti-inflammatory effects and facilitate ischemic muscle regeneration

BACKGROUND AIMS

Skeletal muscle regeneration after severe damage is reliant on local stem cell proliferation and differentiation, processes that are tightly regulated by macrophages. Peripheral artery disease is a globally prevalent cardiovascular disease affecting millions of people. Progression of the disease leads to intermittent claudication, subsequent critical limb ischemia and muscle injury. Tissue-derived and ex vivo-expanded mesenchymal stromal cells (MSCs) for skeletal muscle regeneration have been studied, but pre-clinical and clinical results have not been consistent. As a result, the potential therapeutic efficacy and associated repair mechanisms of MSCs remain unclear. Numerous studies have demonstrated the vulnerability of delivered MSCs, with a precipitous drop in cell viability upon transplantation. This has prompted investigation into the therapeutic benefit of apoptotic cells, microvesicles, exosomes and soluble signals that are released upon cell death.

METHODS

In this study, we characterized various components produced by MSCs after cell death induction under different conditions. We discovered anti-inflammatory and pro-regenerative effects produced by cell components following a freeze and thaw (F&T) process on macrophage polarization in vitro. We further investigated the underlying mechanisms of macrophage polarization by those components resulting from severe cell death induction.

RESULTS

We found potent therapeutic effects from F&T-induced cell debris are dependent on the externalization of phosphatidylserine on the plasma membrane. In contrast, effects from the supernatant of F&T-induced cell death primarily depends on the released protein content. We then applied the F&T-induced cell supernatant to an animal model of peripheral artery disease to treat muscle injury caused by severe ischemia. Treatment with the F&T supernatant but not the vulnerable MSCs resulted in significantly improved recovery of muscle function, blood flow and morphology and inflammation resolution in the affected muscles 2 weeks after injury.

CONCLUSIONS

This study validates the therapeutic potential of F&T-induced supernatant obviating the need for a viable population from vulnerable MSCs to treat injury, thus providing a roadmap for cell-free therapeutic approaches for tissue regeneration.

Enriched adipose stem cell secretome as an effective therapeutic strategy for in vivo wound repair and angiogenesis

The therapeutic potential of adipose tissue-derived mesenchymal stem cells (ADMSCs) is well studied for use in non-healing wounds. However, concerns on the transplantable cell number requirement, cell expansion, cell viability, retained cell multipotency and the limited cell implantation time for efficient impact hinders cell therapy. Recent literature is much inclined to the superiority of the ADMSCs' secretome, pre-dominating its paracrine-mediated therapeutic impact. In this context, the possibility of attaining accelerated wound angiogenesis through non-viral mediated enrichment of the ADMSCs secretome with pro-angiogenic growth factors (AGF) seems promising. Accordingly, this study aimed to explore the effect of AGF-enriched ADMSCs secretome for accelerating wound angiogenesis and repair in acute large area full thickness excision rabbit wound model, as adopted from Salgado et al. (Chir Buchar Rom 108:706-710, 1990). Using sub-dermal single-dose injections along the margin of the dorsal wound, native ADMSCs secretome, AGF-enriched ADMSC secretome, allogenic rabbit ADMSCs and a combination of AGF-enriched ADMSC secretome with allogenic rabbit ADMSCs were transplanted independently. Twenty-eight days (28 days) post-transplantation, histopathological analysis was performed to assess the effect. Hematoxylin and eosin (H&E) staining showed enhanced epithelization, notable granulation tissue and collagen fiber deposition in AGF-enriched secretome transplanted groups. This was confirmed by elevated CD31 detection, faster wound closure time and collagen organization. The use of single-dose AGF-enriched ADMSCs' secretome for therapeutic angiogenesis and wound repair seems to be a promising cell-free therapeutic option. Further investigations using multiple doses on larger animal groups remains to be explored in order to ascertain the comparative potential of AGF-enriched ADMSCs' secretome.

Stem Cell's Secretome Delivery Systems

Stem cells' secretome contains biomolecules that are ready to give therapeutic activities. However, the biomolecules should not be administered directly because of their in vivo instability. They can be degraded by enzymes or seep into other tissues. There have been some advancements in localized and stabilized secretome delivery systems, which have increased their effectiveness. Fibrous, in situ, or viscoelastic hydrogel, sponge-scaffold, bead powder/ suspension, and bio-mimetic coating can maintain secretome retention in the target tissue and prolong the therapy by sustained release. Porosity, young's modulus, surface charge, interfacial interaction, particle size, adhesiveness, water absorption ability, in situ gel/film, and viscoelasticity of the preparation significantly affect the quality, quantity, and efficacy of the secretome. Therefore, the dosage forms, base materials, and characteristics of each system need to be examined to develop a more optimal secretome delivery system. This article discusses the clinical obstacles and potential solutions for secretome delivery, characterization of delivery systems, and devices used or potentially used in secretome delivery for therapeutic applications. This article concludes that secretome delivery for various organ therapies necessitates the use of different delivery systems and bases. Coating, muco-, and cell-adhesive systems are required for systemic delivery and to prevent metabolism. The lyophilized form is required for inhalational delivery, and the lipophilic system can deliver secretomes across the blood-brain barrier. Nano-sized encapsulation and surface-modified systems can deliver secretome to the liver and kidney. These dosage forms can be administered using devices such as a sprayer, eye drop, inhaler, syringe, and implant to improve their efficacy through dosing, direct delivery to target tissues, preserving stability and sterility, and reducing the immune response.

Secretome of Mesenchymal Stromal Cells as a Possible Innovative Therapeutic Tool in Facial Nerve Injury Treatment

Facial nerve palsy is a serious neurological condition that strongly affects patient everyday life. Standard treatments provide insufficient improvement and are burdened with the risk of severe complications, e.g., facial synkinesis. Mesenchymal stromal cell-based therapies are a novel and extensively developed field which offers new treatment approaches with promising results in regards to the nervous tissue regeneration. The potential of mesenchymal stromal cells (MSCs) to aid the regeneration of damaged nerves has been demonstrated in several preclinical models, as well as in several clinical trials. However, therapies based on cell transplantation are difficult to standardize in the manner similar to that of routine clinical practices. On the other hand, treatments based on mesenchymal stromal cell secretome harness the proregenerative features of mesenchymal stromal cells but relay on a product with measurable parameters that can be put through standardization procedures and deliver a fully controllable end-product. Utilization of mesenchymal stromal cell secretome allows the controlled dosage and standardization of the components to maximize the therapeutic potential and ensure safety of the end-product.

Pretreated Mesenchymal Stem Cells and Their Secretome: Enhanced Immunotherapeutic Strategies

Mesenchymal stem cells (MSCs) with self-renewing, multilineage differentiation and immunomodulatory properties, have been extensively studied in the field of regenerative medicine and proved to have significant therapeutic potential in many different pathological conditions. The role of MSCs mainly depends on their paracrine components, namely secretome. However, the components of MSC-derived secretome are not constant and are affected by the stimulation MSCs are exposed to. Therefore, the content and composition of secretome can be regulated by the pretreatment of MSCs. We summarize the effects of different pretreatments on MSCs and their secretome, focusing on their immunomodulatory properties, in order to provide new insights for the therapeutic application of MSCs and their secretome in inflammatory immune diseases.

Ghost messages: cell death signals spread

Cell death is a mystery in various forms. Whichever type of cell death, this is always accompanied by active or passive molecules release. The recent years marked the renaissance of the study of these molecules showing they can signal to and communicate with recipient cells and regulate physio- or pathological events. This review summarizes the defined forms of messages cells could spread while dying, the effects of these signals on the target tissue/cells, and how these types of communications regulate physio- or pathological processes. By doing so, this review hopes to identify major unresolved questions in the field, formulate new hypothesis worthy of further investigation, and when possible, provide references for the search of novel diagnostic/therapeutics agents. Video abstract.

A survey to evaluate parameters governing the selection and application of extracellular vesicle isolation methods

Extracellular vesicles (EVs) continue to gain interest across the scientific community for diagnostic and therapeutic applications. As EV applications diversify, it is essential that researchers are aware of challenges, in particular the compatibility of EV isolation methods with downstream applications and their clinical translation. We report outcomes of the first cross-comparison study looking to determine parameters (EV source, starting volume, operator experience, application and implementation parameters such as cost and scalability) governing the selection of popular EV isolation methods across disciplines. Our findings highlighted an increased clinical focus, with 36% of respondents applying EVs in therapeutics and diagnostics. Data indicated preferential selection of ultracentrifugation for therapeutic applications, precipitation reagents in clinical settings and size exclusion chromatography for diagnostic applications utilising biofluids. Method selection was influenced by operator experience, with increased method diversity when EV research was not the respondents primary focus. Application and implementation criteria were indicated to be major influencers in method selection, with UC and SEC chosen for their abilities to process large and small volumes, respectively. Overall, we identified parameters influencing method selection across the breadth of EV science, providing a valuable overview of practical considerations for the effective translation of research outcomes.

Signaling pathways of adipose stem cell-derived exosomes promoting muscle regeneration

ABSTRACT

Severe muscle injury is still a challenging clinical problem. Exosomes derived from adipose stem cells (ASC-exos) may be a potential therapeutic tool, but their mechanism is not completely clear. This review aims to elaborate the possible mechanism of ASC-exos in muscle regeneration from the perspective of signal pathways and provide guidance for further study. Literature cited in this review was acquired through PubMed using keywords or medical subject headings, including adipose stem cells, exosomes, muscle regeneration, myogenic differentiation, myogenesis, wingless/integrated (Wnt), mitogen-activated protein kinases, phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B (PI3K/Akt), Janus kinase/signal transducers and activators of transcription, and their combinations. We obtained the related signal pathways from proteomics analysis of ASC-exos in the literature, and identified that ASC-exos make different contributions to multiple stages of skeletal muscle regeneration by those signal pathways.

Current Perspectives on Adult Mesenchymal Stromal Cell-Derived Extracellular Vesicles: Biological Features and Clinical Indications

Extracellular vesicles (EVs) constitute one of the main mechanisms by which cells communicate with the surrounding tissue or at distance. Vesicle secretion is featured by most cell types, and adult mesenchymal stromal cells (MSCs) of different tissue origins have shown the ability to produce them. In recent years, several reports disclosed the molecular composition and suggested clinical indications for EVs derived from adult MSCs. The parental cells were already known for their roles in different disease settings in regulating inflammation, immune modulation, or transdifferentiation to promote cell repopulation. Interestingly, most reports also suggested that part of the properties of parental cells were maintained by isolated EV populations. This review analyzes the recent development in the field of cell-free therapies, focusing on several adult tissues as a source of MSC-derived EVs and the available clinical data from in vivo models.

Extracellular Vesicles Derived from Human Bone Marrow Stem Cells Inhibit Acute Lymphoblastic Leukemia Cell Growth by Inhibiting MAPK Pathway via the miR-29b-3p/GDF15 Axis

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is a common hematologic neoplastic disease. This study discussed the effect of extracellular vesicles (EVs) released from bone marrow mesenchymal stem cells (BMSCs) on ALL cells and the mechanism.

METHODS

BMSCs-EVs were isolated by differential centrifugation and identified. The effect of BMSCs-EVs on ALL cell proliferation and apoptosis was evaluated. The expression of miR-29b-3p in ALL cells and EVs was detected. The uptake of EVs by ALL cells was observed. The effect of miR-29b-3p on ALL cell proliferation and apoptosis was assessed after silencing miR-29b-3p. The targeting relation of miR-29b-3p and GDF15 was analyzed by bioinformatics website and dual-luciferase assay. The role of GDF15 in proliferation and apoptosis of ALL cells was further confirmed, and Western blot assay was performed to measure MAPK pathway-related protein levels.

RESULTS

BMSC-derived EVs inhibited proliferation and promoted apoptosis of ALL cells, as shown by the up-regulation of caspase-3 and Bax expressions and down-regulation of Bcl-2 expression. EVs carried miR-29b-3p into ALL cells, upregulated miR-29b-3p expression in ALL cells, and inhibited GDF15 expression. Silencing of miR-29b-3p or overexpression of GDF15 partially reversed the effect of EVs. EVs inhibited the MAPK pathway through the miR-29b-3p/GDF15 axis.

CONCLUSION

BMSCs-EVs carried miR-29b-3p into ALL cells, upregulated miR-29b-3p, and inhibited GDF15 to suppress the MAPK pathway and further inhibit proliferation and promote apoptosis of ALL cells.

Skeletal Muscle Regeneration in Cardiotoxin-Induced Muscle Injury Models

Skeletal muscle injuries occur frequently in daily life and exercise. Understanding the mechanisms of regeneration is critical for accelerating the repair and regeneration of muscle. Therefore, this article reviews knowledge on the mechanisms of skeletal muscle regeneration after cardiotoxin-induced injury. The process of regeneration is similar in different mouse strains and is inhibited by aging, obesity, and diabetes. Exercise, microcurrent electrical neuromuscular stimulation, and mechanical loading improve regeneration. The mechanisms of regeneration are complex and strain-dependent, and changes in functional proteins involved in the processes of necrotic fiber debris clearance, M1 to M2 macrophage conversion, SC activation, myoblast proliferation, differentiation and fusion, and fibrosis and calcification influence the final outcome of the regenerative activity.

Adipose-Secreted Exosomes and Their Pathophysiologic Effects on Skeletal Muscle

Due to its prominent secretory activity, adipose tissue (AT) is now considered a major player in the crosstalk between organs, especially with skeletal muscle. In which, exosomes are effective carriers for the intercellular material transfer of a wide range of molecules that can influence a series of physiological and pathological processes in recipient cells. Considering their underlying roles, the regulatory mechanisms of adipose-secreted exosomes and their cellular crosstalk with skeletal muscle have received great attention in the field. In this review, we describe what is currently known of adipose-secreted exosomes, as well as their applications in skeletal muscle pathophysiology.

“Adipose-derived mesenchymal stem cell therapy for the management of female sexual dysfunction: Literature reviews and study design of a clinical trial”

Hormone imbalance and female sexual dysfunction immensely affect perimenopausal female health and quality of life. Hormone therapy can improve female hormone deficiency, but long-term use increases the risk of cardiovascular diseases and cancer. Therefore, it is necessary to develop a novel effective treatment to achieve long-term improvement in female general and sexual health. This study reviewed factors affecting syndromes of female sexual dysfunction and its current therapy options. Next, the authors introduced research data on mesenchymal stromal cell/mesenchymal stem cell (MSC) therapy to treat female reproductive diseases, including Asherman’s syndrome, premature ovarian failure/primary ovarian insufficiency, and vaginal atrophy. Among adult tissue-derived MSCs, adipose tissue-derived stem cells (ASCs) have emerged as the most potent therapeutic cell therapy due to their abundant presence in the stromal vascular fraction of fat, high proliferation capacity, superior immunomodulation, and strong secretion profile of regenerative factors. Potential mechanisms and side effects of ASCs for the treatment of female sexual dysfunction will be discussed. Our phase I clinical trial has demonstrated the safety of autologous ASC therapy for women and men with sexual hormone deficiency. We designed the first randomized controlled crossover phase II trial to investigate the safety and efficacy of autologous ASCs to treat female sexual dysfunction in perimenopausal women. Here, we introduce the rationale, trial design, and methodology of this clinical study. Because aging and metabolic diseases negatively impact the bioactivity of adult-derived MSCs, this study will use ASCs cultured in physiological oxygen tension (5%) to cope with these challenges. A total of 130 perimenopausal women with sexual dysfunction will receive two intravenous infusions of autologous ASCs in a crossover design. The aims of the proposed study are to evaluate 1) the safety of cell infusion based on the frequency and severity of adverse events/serious adverse events during infusion and follow-up and 2) improvements in female sexual function assessed by the Female Sexual Function Index (FSFI), the Utian Quality of Life Scale (UQOL), and the levels of follicle-stimulating hormone (FSH) and estradiol. In addition, cellular aging biomarkers, including plasminogen activator inhibitor-1 (PAI-1), p16 and p21 expression in T cells and the inflammatory cytokine profile, will also be characterized. Overall, this study will provide essential insights into the effects and potential mechanisms of ASC therapy for perimenopausal women with sexual dysfunction. It also suggests direction and design strategies for future research.

Protective effect of adipose-derived stromal cell-secretome attenuate autophagy induced by liver ischemia–reperfusion and partial hepatectomy

Background

The therapeutic effects of adipose-derived mesenchymal stromal cells (ADSCs) may be mainly mediated by their paracrine effects. The ADSC-secretome can ameliorate hepatic ischemia–reperfusion injury (IRI). We explored the therapeutic effect of the ADSC-secretome from the perspective of excessive hepatocyte autophagy induced by hepatic IRI.

Methods

We established a miniature pig model of hepatic ischemia–reperfusion (I/R) and hepatectomy using a laparoscopic technique and transplanted ADSCs and the ADSC-secretome into the liver parenchyma immediately after surgery. Liver injury and hepatocyte autophagy were evaluated by histopathological examination and assessment of relevant cytokines and other factors.

Results

The results showed that the ADSC-secretome alleviated the pathological changes of liver tissue and the microstructural damage of hepatocytes after IRI. Moreover, the expression levels of autophagy-related markers including Beclin-1, ATG5, ATG12, and LC3II/LC3I decreased, whereas those of p62 increased during phagophore expansion. Furthermore, the expression levels of markers related to the autophagy inhibition pathway phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR), including PI3K, Akt, and mTOR, increased.

Conclusion

The ADSC-secretome attenuates hepatic I/R and hepatectomy-induced liver damage by inhibiting autophagy, which is possibly mediated by activation of the PI3K/Akt/mTOR signaling pathway. In addition, there was no significant difference between ADSCs and the ADSC-secretome in the regulation of hepatocyte autophagy. Therefore, ADSCs may improve the excessive autophagy-induced injury of hepatocytes in hepatic I/R and hepatectomy through paracrine effect. Our findings provide new insight into the therapeutic potential of cell-free products, which could replace cell therapy in liver diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03109-2.

Cell Secretome Strategies for Controlled Drug Delivery and Wound-Healing Applications

There is significant interest in using stem cells in the management of cutaneous wounds. However, potential safety, efficacy, and cost problems associated with whole-cell transplantation hinder their clinical application. Secretome, a collective of mesenchymal stem-cell-stored paracrine factors, and immunomodulatory cytokines offer therapeutic potential as a cell-free therapy for the treatment of cutaneous wounds. This review explores the possibility of secretome as a treatment for cutaneous wounds and tissue regeneration. The review mainly focuses on in vitro and in vivo investigations that use biomaterials and secretome together to treat wounds, extend secretome retention, and control release to preserve their biological function. The approaches employed for the fabrication of biomaterials with condition media or extracellular vesicles are discussed to identify their future clinical application in wound treatment.

Complexed Polymer Film-Forming Spray: An Optimal Delivery System for Secretome of Mesenchymal Stem Cell as Diabetic Wound Dressing?

Diabetes-related wounds have physiological factors that make healing more complicated. High sugar levels can increase microbial infection risk while limiting nutrition and oxygen transfer to the wound area. The secretome of mesenchymal stem cells has been widely known for its efficacy in regenerative therapy. However, applying the secretome directly to the wound can reduce its effectiveness. In this review, we examined the literature on synthesizing the combinations of carboxymethyl chitosan, hyaluronic acid, and collagen tripeptides, as well as the possibility of physicochemical properties enhancement of the hydrogel matrix, which could potentially be used as an optimal delivery system of stem cell's secretome for diabetic wound healing.

Well-orchestrated physico-chemical and biological factors for enhanced secretion of osteogenic and angiogenic extracellular vesicles by mesenchymal stem cells in a 3D culture format

The secretome of mesenchymal stem cells (MSCs) is being studied for its regenerative potential for the treatment of various disorders, including bone diseases. However, mimicking the physiological parameters of native bone could further improve MSCs' secretory profile. The proteomic analysis revealed that MSCs have a diverse secretory profile depending on the cell formats used to grow them, such as two-dimensional (2D) or three-dimensional (3D) microenvironments. Stem cells are given biochemical and biophysical stimuli in a 3D milieu that mimics in vivo situations. Compared to the gold standard monolayer culture, extracellular vesicles (EVs) released under 3D conditions improved the EV cargo numerically and qualitatively. The higher requirements of EVs in clinical trials with consistent therapeutic potential are challenging. This review discusses the impact of cell culture formats on the regenerative potential of MSCs, specifically in bone regeneration. The poor yield and heterogeneity issues have hampered the therapeutic usage of EVs. Therefore, this review further explores various engineering approaches that could enhance EVs' scalability from MSCs and their therapeutic effectiveness beyond their native utility in bone tissue regeneration. This review also highlights some of the upcoming 3D approaches/models that might be useful for the enhanced secretion of therapeutic EVs from stem cells. Finally, we discuss possible future directions and conclusions in this domain.

Extracellular vesicle and soluble fractions of adipose tissue-derived mesenchymal stem cells secretome induce inflammatory cytokines modulation in an in vitro model of discogenic pain

BACKGROUND CONTEXT

Mesenchymal stem cells (MSCs) secretome or conditioned medium (CM) is a complex cocktail of different molecules, some of which, particularly those contained in extracellular vesicles, already have proven therapeutic applications.

PURPOSE

CM may well represent promising therapy for discogenic pain and the intention of this work is to assess its therapeutic potential using an in vitro model of this condition.

STUDY DESIGN

This is an experimental study.

METHODS

Our in vitro model comprised nucleus pulposus (NP) and annulus fibrosus (AF) cells inflamed with TNF. To assess the potential therapeutic value of CM and its components, extracellular vesicles (EVs) and soluble culture fraction (SF), cell inflammation took place under 3 different conditions: either in the presence of whole CM, isolated EVs or SF, and concentrations of pro-inflammatory cytokines, metalloproteinases (MMPs) and neurotrophic factors produced in all 3 cases were compared.

RESULTS

In the presence of whole CM, both in vitro gene expression by the NP and AF test cells and analysis of their protein content showed high modulatory effects on inflammation and MMP inhibition. The presence of EVs and SF showed similar but much smaller effects, and this was particularly marked in the case of NP cells.

CONCLUSIONS

Our results show that, compared to EVs and SF, the presence of whole CM has the greatest positive effect on the modulation of pro-inflammatory and catabolic factors. These observations suggest that CM could protect against inflammation and the resulting intervertebral disc (IVD) degeneration that leads to discogenic pain.

CLINICAL SIGNIFICANCE

Many patients' expectations are not met by current non-operative and surgical treatments for discogenic low back pain. We propose the use of the MSCs secretome for assessing its potential as cell-free therapy to treat degenerative disc disease modulating the inflammatory response.

Muscle and Adipose Tissue Communicate with Extracellular Vesicles

In numerous body locations, muscle and adipose tissue are in close contact. Both tissues are endocrine organs that release cytokines, playing a crutial role in the control of tissue homeostasis in health and diseases. Within this context, the identification of the signals involved in muscle–fat crosstalk has been a hot topic over the last 15 years. Recently, it has been discovered that adipose tissue and muscles can release information embedded in lipid-derived nanovesicles called ‘extracellular vesicles’ (EVs), which can modulate the phenotype and the homeostasis of neighboring recipient cells. This article reviews knowledge on EVs and their involvement in the communication between adipose tissue and muscle in several body locations. Even if the works are scarce, they have revolutionized our vision in the field of metabolic and cardiovascular diseases.

A “cell-free treatment” for tendon injuries: adipose stem cell-derived exosomes

Tendon injuries are widespread and chronic disorders of the musculoskeletal system, frequently caused by overload of the tendons. Currently, the most common treatment for tendon injuries is "cell-free therapy", of which exosomes, which can treat a host of diseases, including immune disorders, musculoskeletal injuries and cardiovascular diseases, are one kind. Among the many sources of exosomes, adipose-derived stem cell exosomes (ASC-Exos) have better efficacy. This is attributed not only to the ease of isolation of adipose tissue, but also to the high differentiation capacity of ASCs, their greater paracrine function, and immunomodulatory capacity compared to other exosomes. ASC-Exos promote tendon repair by four mechanisms: promoting angiogenesis under hypoxic conditions, reducing the inflammatory response, promoting tendon cell migration and proliferation, and accelerating collagen synthesis, thus accelerating tendon healing. This review focuses on describing studies of preclinical experiments with various exosomes, the characteristics of ASC-Exos and their mechanisms of action in tendon healing, as well as elaborating the limitations of ASC-Exos in clinical applications.