Mesenchymal Stem Cell Secretome as an Emerging Cell-Free Alternative for Improving Wound Repair

The mesenchymal stromal cell secretome promotes tissue regeneration and increases macrophage infiltration in acute and methicillin-resistant Staphylococcus aureus-infected skin wounds in vivo

BACKGROUND AIMS

The prevalence of chronic wounds continues to be a burden in human medicine. Methicillin-resistant Staphylococcus aureus (MRSA) is commonly isolated from infected wounds. MRSA infections primarily delay healing by impairing local immune cell functions. This study aimed to investigate the potential of mesenchymal stromal cell (MSC)-secreted bioactive factors, defined as the secretome, to improve innate immune responses in vivo. MSCs were isolated from the bone marrow of horses, which serve as valuable translational models for wound healing. The MSC secretome, collected as conditioned medium (CM), was evaluated in vivo using mouse models of acute and MRSA-infected skin wounds.

METHODS

Punch biopsies were used to create two full-thickness skin wounds on the back of each mouse. Acute wounds were treated daily with control medium or bone marrow-derived MSC (BM-MSC) CM. The antibiotic mupirocin was administered as a positive control for the MRSA-infected wound experiments. Wounds were photographed daily, and wound images were measured to determine the rate of closure. Trichrome staining was carried out to examine wound tissue histologically, and immunofluorescence antibody binding was used to assess immune cell infiltration. Wounds in the MRSA-infected model were swabbed for quantification of bacterial load.

RESULTS

Acute wounds treated with BM-MSC CM showed accelerated wound closure compared with controls, as illustrated by enhanced granulation tissue formation and resolution, increased vasculature and regeneration of hair follicles. This treatment also led to increased neutrophil and macrophage infiltration. Chronic MRSA-infected wounds treated with BM-MSC CM showed reduced bacterial load accompanied by better resolution of granulation tissue formation and increased infiltration of pro-healing M2 macrophages compared with control-treated infected wounds.

CONCLUSIONS

Collectively, our findings indicate that BM-MSC CM exerts pro-healing, immunomodulatory and anti-bacterial effects on wound healing in vivo, validating further exploration of the MSC secretome as a novel treatment option to improve healing of both acute and chronic wounds, especially those infected with antibiotic-resistant bacteria.

The impact of hypoxia preconditioning on mesenchymal stem cells performance in hypertensive kidney disease

BACKGROUND

Autologous mesenchymal stem cells (MSCs) have emerged as a therapeutic option for many diseases. Hypertensive kidney disease (HKD) might impair MSCs' reparative ability by altering the biomolecular properties, but the characteristics of this impairment are unclear. In our previous pre-clinical studies, we found hypoxic preconditioning (HPC) enhanced angiogenesis and suppressed senescence gene expression. Thus, we hypothesize that HPC would improve human MSCs by enhancing their functionality and angiogenesis, creating an anti-inflammatory and anti-senescence environment.

METHODS

MSC samples (n = 12 each) were collected from the abdominal fat of healthy kidney donors (HC), hypertensive patients (HTN), and patients with hypertensive kidney disease (HKD). MSCs were harvested and cultured in Normoxic (20% O2) or Hypoxic (1% O2) conditions. MSC functionality was measured by proliferation assays and cytokine released in conditioned media. Senescence was evaluated by senescence-associated beta-galactosidase (SA-beta-gal) activity. Additionally, transcriptome analysis using RNA-sequencing and quantitative PCR (qPCR) were performed.

RESULTS

At baseline, normoxic HTN-MSCs had higher proliferation capacity compared to HC. However, HPC augmented proliferation in HC. HPC did not affect the release of pro-angiogenic protein VEGF, but increased EGF in HC-MSC, and decreased HGF in HC and HKD MSCs. Under HPC, SA-β-gal activity tended to decrease, particularly in HC group. HPC upregulated mostly the pro-angiogenic and inflammatory genes in HC and HKD and a few senescence genes in HKD.

CONCLUSIONS

HPC has a more favorable functional effect on HC- than on HKD-MSC, reflected in increased proliferation and EGF release, and modest decrease in senescence, whereas it has little effect on HTN or HKD MSCs.

Effect of Multiple-Cycle Collections of Conditioned Media from Different Cell Sources towards Fibroblasts in In Vitro Wound Healing Model

Conditioned media refers to a collection of the used cell culture media. The goal of this study was to evaluate the possible impacts of different conditioned media collected across a number of cycles on the fibroblast proliferation, migration, and profiles of protein release. Human dermal fibroblast (HDF) cells and Wharton jelly mesenchymal stem cells (WJMSC) were cultured and incubated for 3 days prior to being harvested as cycle-1 using the serum-free media F12:DMEM and DMEM, respectively. The procedures were repeatedly carried out until the fifth cycle of conditioned media collection. An in-vitro scratch assay was conducted to measure the effectiveness of wound healing. Collagen hydrogel was combined separately with both the Wharton jelly-conditioned medium (WJCM) and the dermal fibroblast-conditioned medium (DFCM) in order to evaluate the protein release profile. The conditioned medium from many cycles had a lower level of fibroblast attachment than the control (complete medium); however, the growth rate increased from 100 to 250 h-1, when supplemented with a conditioned medium collected from multiple cycles. The wound scratch assay showed that fibroblast cell migration was significantly increased by repeating cycles up to cycle-5 of DFCM, reaching 98.73 ± 1.11%. This was faster than the rate of migration observed in the cycle-5 of the WJCM group, which was 27.45 ± 5.55%. Collagen hydrogel from multiple cycles of DFCM and WJCM had a similar protein release profile. These findings demonstrate the potential for employing repeated cycles of DFCM- and WJCM-released proteins with collagen hydrogel for applications in wound healing.

Research hotspots and emerging trends of mesenchymal stem cells in cardiovascular diseases: a bibliometric-based visual analysis

Background

Mesenchymal stem cells (MSCs) have important research value and broad application prospects in cardiovascular diseases (CVDs). However, few bibliometric analyses on MSCs in cardiovascular diseases are available. This study aims to provide a thorough review of the cooperation and influence of countries, institutions, authors, and journals in the field of MSCs in cardiovascular diseases, with the provision of discoveries in the latest progress, evolution paths, frontier research hotspots, and future research trends in the regarding field.

Methods

The articles related to MSCs in cardiovascular diseases were retrieved from the Web of Science. The bibliometric study was performed by CiteSpace and VOSviewer, and the knowledge map was generated based on data obtained from retrieved articles.

Results

In our study, a total of 4,852 publications launched before August 31, 2023 were accessed through the Web of Science Core Collection (WoSCC) database via our searching strategy. Significant fluctuations in global publications were observed in the field of MSCs in CVDs. China emerged as the nation with the largest number of publications, yet a shortage of high-quality articles was noted. The interplay among countries, institutions, journals and authors is visually represented in the enclosed figures. Importantly, current research trends and hotspots are elucidated. Cluster analysis on references has highlighted the considerable interest in exosomes, extracellular vesicles, and microvesicles. Besides, keywords analysis revealed a strong emphasis on myocardial infarction, therapy, and transplantation. Treatment methods-related keywords were prominent, while keywords associated with extracellular vesicles gathered significant attention from the long-term perspective.

Conclusion

MSCs in CVDs have become a topic of active research interest, showcasing its latent value and potential. By summarizing the latest progress, identifying the research hotspots, and discussing the future trends in the advancement of MSCs in CVDs, we aim to offer valuable insights for considering research prospects.

Emerging Strategies in Mesenchymal Stem Cell-Based Cardiovascular Therapeutics

Cardiovascular diseases continue to challenge global health, demanding innovative therapeutic solutions. This review delves into the transformative role of mesenchymal stem cells (MSCs) in advancing cardiovascular therapeutics. Beginning with a historical perspective, we trace the development of stem cell research related to cardiovascular diseases, highlighting foundational therapeutic approaches and the evolution of cell-based treatments. Recognizing the inherent challenges of MSC-based cardiovascular therapeutics, which range from understanding the pro-reparative activity of MSCs to tailoring patient-specific treatments, we emphasize the need to refine the pro-regenerative capacity of these cells. Crucially, our focus then shifts to the strategies of the fourth generation of cell-based therapies: leveraging the secretomic prowess of MSCs, particularly the role of extracellular vesicles; integrating biocompatible scaffolds and artificial sheets to amplify MSCs' potential; adopting three-dimensional ex vivo propagation tailored to specific tissue niches; harnessing the promise of genetic modifications for targeted tissue repair; and institutionalizing good manufacturing practice protocols to ensure therapeutic safety and efficacy. We conclude with reflections on these advancements, envisaging a future landscape redefined by MSCs in cardiovascular regeneration. This review offers both a consolidation of our current understanding and a view toward imminent therapeutic horizons.

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.

Adipose-Derived Stem Cells' Secretome Attenuates Lesion Size and Parasite Loading in Leishmaniasis Caused by Leishmania Major in Mice

Background

Stem cell-derived secretome (SE) released into the extracellular space contributes to tissue repair. The present study aimed to investigate the impact of isolated secretome (SE) from adipose-derived mesenchymal stem cells (ASCs) on Leishmania major (L. major) lesions in BALB/c mice.

Methods

This experimental study was conducted at Ahvaz University of Medical Sciences (Ahvaz, Iran) in 2021. Forty female BALB/c mice were infected with stationary phase promastigotes through intradermal injection in the bottom of their tail and randomly divided into four groups (n=10 per group). The mice were given SE (20 mg/mL), either alone or in combination with Glucantime (GC, 20 mg/mL/Kg), meglumine antimoniate (20 mg/mL/Kg) for the GC group, and phosphate-buffered saline (PBS) for the control group. After eight weeks, the lesion size, histopathology, the levels of Interleukin 10 (IL-10), and Interleukin 12 (IL-12) were assessed. For the comparison of values between groups, the parametric one-way ANOVA was used to assess statistical significance.

Results

At the end of the experiment, the mice that received SE had smaller lesions (4.56±0.83 mm versus 3.62±0.59 mm, P=0.092), lower levels of IL-10 (66.5±9.7 pg/mL versus 285.4±25.2 pg/mL, P<0.001), and higher levels of IL-12 (152.2±14.2 pg/mL versus 24.2±4.4 pg/mL, P<0.001) than the control. Histopathology findings revealed that mice treated with SE had a lower parasite burden in lesions and spleen than the control group.

Conclusion

The current study demonstrated that ADSC-derived SE could protect mice infected with L. major against leishmaniasis.

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.

Mesenchymal stem cell-derived extracellular vesicles as a cell-free therapy for traumatic brain injury via neuroprotection and neurorestoration

Traumatic brain injury is a serious and complex neurological condition that affects millions of people worldwide. Despite significant advancements in the field of medicine, effective treatments for traumatic brain injury remain limited. Recently, extracellular vesicles released from mesenchymal stem/stromal cells have emerged as a promising novel therapy for traumatic brain injury. Extracellular vesicles are small membrane-bound vesicles that are naturally released by cells, including those in the brain, and can be engineered to contain therapeutic cargo, such as anti-inflammatory molecules, growth factors, and microRNAs. When administered intravenously, extracellular vesicles can cross the blood-brain barrier and deliver their cargos to the site of injury, where they can be taken up by recipient cells and modulate the inflammatory response, promote neuroregeneration, and improve functional outcomes. In preclinical studies, extracellular vesicle-based therapies have shown promising results in promoting recovery after traumatic brain injury, including reducing neuronal damage, improving cognitive function, and enhancing motor recovery. While further research is needed to establish the safety and efficacy of extracellular vesicle-based therapies in humans, extracellular vesicles represent a promising novel approach for the treatment of traumatic brain injury. In this review, we summarize mesenchymal stem/stromal cell-derived extracellular vesicles as a cell-free therapy for traumatic brain injury via neuroprotection and neurorestoration and brain-derived extracellular vesicles as potential biofluid biomarkers in small and large animal models of traumatic brain injury.

The effect of fibroblast growth factor-2 on the outcomes of tooth replantation: A systematic review of animal studies

Background/Aim: The ideal treatment of tooth avulsion is replantation. However, replanting teeth may lead to root resorption. Fibroblast growth factor-2 (FGF-2) is a cytokine that plays an important role in wound repair and tissue regeneration. Recently, FGF-2 has been studied a potential regenerative agent to prevent root resorption and ankylosis. The aim of this review is to analyze and summarize the currently available literature focusing on using FGF-2 based regenerative modalities to improve the outcomes of tooth replantation. Materials and Methods: An electronic search was conducted via PubMed/Medline, Google Scholar and ISI Web of Knowledge, using the Medical Subject Headings (MeSH) terms "Basic fibroblast growth factor," "Fibroblast growth factor-2," "tooth replantation," and "replantation" for studies published between January 2001 and June 2021. Data was extracted and quality assessment was carried using the ARRIVE guidelines. Results: Nine animal studies were included in this review. In six studies, FGF-2 had a favorable effect on the tissue regeneration around roots of replanted teeth when compared to other treatment groups. However, quality assessment of the studies revealed many sources of bias and deficiencies in the studies. Conclusions: Within the limitations of this study, it may be concluded that FGF-2 may improve the outcomes of delayed replantation of avulsed teeth. However, more long-term animal studies, with improved experimental designs, and clinical trials are required to determine the clinical potential of the growth factor in improving the outcomes of delayed tooth replantation.

Mesenchymal stem cell secretome ameliorates over-expression of soluble fms-like tyrosine kinase-1 (sFlt-1) and fetal growth restriction (FGR) in animal SLE model

INTRODUCTION

In the near future, stem cell research may lead to several major therapeutic innovations in medical practice. Secretome, a "by-product" of stem cell line cultures, has many advantages. Its easiness of storage, usage, and fast direct effect are some of those to consider. Fetal growth restriction (FGR) remains one of the significant challenges in maternal-fetal and neonatal medicine. Placentation failure is one of the most profound causal and is often related to increasing sFlt-1 in early pregnancy. This study aimed to investigate hUC-MSC secretome in ameliorating sFlt-1 and how to improve outcomes in preventing FGR in an animal model.

MATERIALS AND METHODS

Pristane-induced systemic lupus erythematosus (SLE) in a mouse model was used to represent placentation failure and its consequences. Twenty-one mice were randomized into three groups: (I) normal pregnancy, (II) SLE, and (III) SLE with secretome treatment. Pristane was administered in all Groups four weeks prior mating period. Secretome was derived from human umbilical cord mesenchymal stem cells (hUC-MSC) conditioned medium on the 3rd and 4th passage, around day-21 until day-28 from the start of culturing process. Mesenchymal stem cell was characterized using flow cytometry for CD105+, CD90+, and CD73+ surface antigen markers. Immunohistochemistry anlysis by using Remmele's Immunoreactive Score (IRS) was used to quantify the placental sFlt-1 expression in each group. Birth weight and length were analyzed as the secondary outcome. The number of fetuses obtained was also calculated for pregnancy loss comparison between Groups.

RESULTS

The administration of secretome of hUC-MSC was found to lower the expression of the placental sFlt-1 significantly in the pristane SLE animal model (10.30 ± 1.40 vs. 4.98 ± 2.57; p < 0.001) to a level seen in normal mouse pregnancies in Group I (3.88 ± 0.49; p = 0.159). Secretome also had a significant effect on preventing fetal growth restriction in the pristane SLE mouse model (birth weight: 354.29 ± 80.76 mg vs. 550 ± 64.03 mg; p < 0.001 and birth length: 14.43 ± 1.27 mm vs. 19.00 ± 1.41 mm), comparable to the birth weight and length of the normal pregnancy in Group I (540.29 ± 75.47 mg and 18.14 ± 1.34 mm, p = 0.808 and = 0.719). Secretome administration also showed a potential action to prevent high number of pregnancy loss as the number of fetuses obtained could be similar to those of mice in the normal pregnant Group (7.71 ± 1.11 vs. 7.86 ± 1.06; p = 0.794).

CONCLUSIONS

Administration of secretome lowers sFlt-1 expression in placenta, improves fetal growth, and prevents pregnancy loss in a mouse SLE model.

Effectiveness of Mesenchymal Stem Cell Secretome on Wound Healing: A Systematic Review and Meta-analysis

BACKGROUND

Secretome provides promising potential in replacing cell-based therapies in wound repair therapy. This study aimed to systematically review and conduct a meta-analysis on the effectiveness of secretome in promoting wound healing.

METHODS

To ensure the rigor and transparency of our study, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, as registered in PROSPERO with ID: CRD42023412671. We conducted a comprehensive search on four electronic databases to identify studies evaluating the effect of secretome on various clinical parameters of wound repair. In addition, we evaluated the risk of bias for each study using the Jadad and Newcastle-Ottawa scale. To synthesize the data, we employed a fixed-effects model and calculated the mean difference or odds ratio (OR) with a 95% confidence interval (CI).

RESULTS

Based on six included articles, secretome is known to affect several clinical parameters in wound healing included the size and depth of ulcers during healing; the E´chelle d'évaluation clinique des cicatrices d'acne (ECCA) score, epidermal thickness, collagen fibers, abnormal elastic tissues, volume of atrophic acne scars, skin pore volume, and erythema during acne scar healing; and microcrust areas, erythema index, transepidermal water loss, volume of atrophic acne scars, erythema, and relative gene expression of procollagen type I, procollagen type III, and elastin were evaluated in wound healing after laser treatment. Meta-analysis studies showed that secretome reduced ulcer size (mean difference: 0.87, 95% CI of 0.37-1.38, p = 0.0007), decreased ulcer depth (mean difference: 0.18, 95% CI of 0.11-0.25, p < 0.00001), and provided patient satisfaction (odds ratio: 9.71, 95% CI of 3.47-21.17, p < 0.0001). However, secretome failed to reach significance in clinical improvement (OR 0.38, 95% CI 0.10, 1.53, p = 0.06).

CONCLUSION

The secretome provides good effectiveness in accelerating wound healing through a mechanism that correlates with several clinical parameters of wound repair.

Acoustofluidic Interfaces for the Mechanobiological Secretome of MSCs

While mesenchymal stem cells (MSCs) have gained enormous attention due to their unique properties of self-renewal, colony formation, and differentiation potential, the MSC secretome has become attractive due to its roles in immunomodulation, anti-inflammatory activity, angiogenesis, and anti-apoptosis. However, the precise stimulation and efficient production of the MSC secretome for therapeutic applications are challenging problems to solve. Here, we report on Acoustofluidic Interfaces for the Mechanobiological Secretome of MSCs: AIMS. We create an acoustofluidic mechanobiological environment to form reproducible three-dimensional MSC aggregates, which produce the MSC secretome with high efficiency. We confirm the increased MSC secretome is due to improved cell-cell interactions using AIMS: the key mediator N-cadherin was up-regulated while functional blocking of N-cadherin resulted in no enhancement of the secretome. After being primed by IFN-γ, the secretome profile of the MSC aggregates contains more anti-inflammatory cytokines and can be used to inhibit the pro-inflammatory response of M1 phenotype macrophages, suppress T cell activation, and support B cell functions. As such, the MSC secretome can be modified for personalized secretome-based therapies. AIMS acts as a powerful tool for improving the MSC secretome and precisely tuning the secretory profile to develop new treatments in translational medicine.

MFGE-8 identified in fetal mesenchymal-stromal-cell-derived exosomes ameliorates acute hepatic failure pathology

Liver transplantation is the gold-standard therapy for acute hepatic failure (AHF) with limitations related to organ shortage and life-long immunosuppressive therapy. Cell therapy emerges as a promising alternative to transplantation. We have previously shown that IL-10 and Annexin-A1 released by amniotic fluid human mesenchymal stromal cells (AF-MSCs) and their hepatocyte progenitor-like (HPL) or hepatocyte-like (HPL) cells induce liver repair and downregulate systemic inflammation in a CCl4-AHF mouse model. Herein, we demonstrate that exosomes (EXO) derived from these cells improve liver phenotype in CCl4-induced mice and promote oval cell proliferation. LC-MS/MS proteomic analysis identified MEFG-8 in EXO cargo that facilitates rescue of AHF by suppressing PI3K signaling. Administration of recombinant MFGE-8 protein also reduced liver damage in CCl4-induced mice. Clinically, MEFG-8 expression was decreased in liver biopsies from AHF patients. Collectively, our study provides proof-of-concept for an innovative, cell-free, less immunogenic, and non-toxic alternative strategy for AHF.

Secretome profile of TNF-α-induced human umbilical cord mesenchymal stem cells unveils biological processes relevant to skin wound healing

Aim: To profile and study the proteins responsible for the beneficial effect of the TNF-α-induced human umbilical cord mesenchymal stem cells (hUCMSCs) secretome in wound healing. Methods: The hUCMSCs secretome was generated with (induced) or without (uninduced) TNF-α and was subsequently analyzed by liquid chromatography-mass spectrometry, immunoassay and in vitro scratch assay. Results: Proteomic analysis revealed approximately 260 proteins, including 51 and 55 unique proteins in the induced and uninduced secretomes, respectively. Gene ontology analysis disclosed that differential proteins in the induced secretome mainly involved inflammation-related terms. The induced secretome, consisting of higher levels of FGFb, VEGF, PDGF and IL-6, significantly accelerated wound closure and enhanced MMP-13 secretion in HaCaT keratinocytes. Conclusion: The secretome from induced hUCMSCs includes factors that promote wound closure.

Mesenchymal Stem Cell Extracellular Vesicles from Tissue-Mimetic System Enhance Epidermal Regeneration via Formation of Migratory Cell Sheets

BACKGROUND

The secretome of adipose-derived mesenchymal stem cells (ASCs) offers a unique approach to understanding and treating wounds, including the critical process of epidermal regeneration orchestrated by keratinocytes. However, 2D culture techniques drastically alter the secretory dynamics of ASCs, which has led to ambiguity in understanding which secreted compounds (e.g., growth factors, exosomes, reactive oxygen species) may be driving epithelialization.

METHODS

A novel tissue-mimetic 3D hydrogel system was utilized to enhance the retainment of a more regenerative ASC phenotype and highlight the functional secretome differences between 2D and 3D. Subsequently, the ASC-secretome was stratified by molecular weight and the presence/absence of extracellular vesicles (EVs). The ASC-secretome fractions were then evaluated to assess for the capacity to augment specific keratinocyte activities.

RESULTS

Culture of ASCs within the tissue-mimetic system enhanced protein secretion ~ 50%, exclusively coming from the > 100 kDa fraction. The ASC-secretome ability to modulate epithelialization functions, including migration, proliferation, differentiation, and morphology, resided within the "> 100 kDa" fraction, with the 3D ASC-secretome providing the greatest improvement. 3D ASC EV secretion was enhanced two-fold and exhibited dose-dependent effects on epidermal regeneration. Notably, ASC-EVs induced morphological changes in keratinocytes reminiscent of native regeneration, including formation of stratified cell sheets. However, only 3D-EVs promoted collective cell sheet migration and an epithelial-to-mesenchymal-like transition in keratinocytes, whereas 2D-EVs contained an anti-migratory stimulus.

CONCLUSION

This study demonstrates how critical the culture environment is on influencing ASC-secretome regenerative capabilities. Additionally, the critical role of EVs in modulating epidermal regeneration is revealed and their translatability for future clinical therapies is discussed.

Cyclic mechanical stretch pre-stimulated bone marrow mesenchymal stem cells promote the healing of infected bone defect in a mouse model

Cyclic mechanical stretch (CMS) is an effective method to accelerate mesenchymal stem cells (MSCs) differentiation. Here, CMS pre-stimulated bone marrow MSCs (CMS-BMSCs) was investigated, characterized and evaluated the therapeutic potential of CMS-BMSCs on the treatment of infected bone defect in mouse model. BMSCs were obtained from C57BL/6J mice and then subjected to CMS. The osteogenic differentiation capacity of BMSCs was evaluated by alkaline phosphatase (ALP) assay, Alizarin Red staining, qRT-PCR, and Western blot. The pre-stimulated BMSCs were transplanted into infected bone defect mice, osteogenesis, antibacterial effects, and inflammatory responses were examined. CMS significantly increased ALP activity and the expression of osteoblastic genes (col1a1, runx2, and bmp7) and enhanced osteogenic differentiation and nrf2 expression of BMSCs. Transplantation of CMS pre-stimulated BMSCs promoted the healing of infected bone defect in mice, enhanced antibacterial effects, and reduced inflammatory responses in the mid-sagittal section of the fracture callus. CMS pre-stimulated BMSCs enhance the healing of infected bone defects in a mouse model, suggesting a potential therapeutic strategy for treating infected bone defects.

Paracrine signalling between keratinocytes and SVF cells results in a new secreted cytokine profile during wound closure

Stromal vascular fraction (SVF) cells, and the adipose-derived mesenchymal stem cells they contain, have shown enhanced wound healing in vitro and in vivo, yet their clinical application has been limited. In this regard, understanding the mechanisms that govern SVF-enhanced wound healing would improve their application in the clinic. Here, we show that the SVF cells and keratinocytes engage in a paracrine crosstalk during wound closure, which results in a new cytokine profile that is distinct from the cytokines regularly secreted by either cell type on their own. We identify 11 cytokines, 5 of which are not regularly secreted by the SVF cells, whose expressions are significantly increased during wound closure by the keratinocytes. This new cytokine profile could be used to accelerate wound closure and initiate re-epithelialization without the need to obtain the SVF cells from the patient.

A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome

Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.

Potential Utilisation of Secretome from Ascorbic Acid-Supplemented Stem Cells in Combating Skin Aging: Systematic Review of A Novel Idea

The secretome of stem cells consists of a spectrum of bioactive factors secreted by stem cells grown in culture mediacytokines, chemokines, and growth factors in addition to extracellular vesicles (exosomes and microvesicles). Ease of handling and storage of secretomes along with their bioactivity towards processes in skin aging and customizability makes them an appealing prospective therapy for skin aging. This systematic review aims to investigate the potential usage of ascorbic acid (AA)-supplemented stem cell secretomes (SCS) in managing skin aging. We extracted articles from three databases: PubMed, Scopus, and Cochrane. This review includes in vitro, in vivo, and clinical studies published in English that discuss the correlation of AA-supplemented-SCS with skin aging. We identified 1111 articles from database and non-database sources from which nine studies met the inclusion criteria. However, the study results were less specific due to the limited amount of available research that specifically assessed the effects of AAsupplemented SCS in skin aging. Although further studies are necessary, the AA modification of SCS is a promising potential for improving skin health.

The efficacy of topical adipose mesenchymal stem cell-conditioned medium versus framycetin gauze dressing in chronic plantar ulcer of leprosy: A randomized controlled trial

Background Wound healing shows a unique interaction of several cells, growth factors and cytokines. The healing of chronic plantar ulcer of leprosy is influenced by various factors, one of which is the concentration of growth factors and cytokines related to the pathogenesis of impaired wound healing. Growth factors and cytokines can be found in the secretome of adipose mesenchymal stem cells. Aim To compare the effectiveness of topical adipose mesenchymal stem cell-conditioned medium and framycetin gauze dressing only on the healing of chronic plantar ulcer of leprosy. Methods In this randomised controlled trial, 32 patients with chronic plantar ulcer of leprosy were recruited. After detailed clinical and initial debridement, patients were randomised to two groups to receive either topical adipose mesenchymal stem cell-conditioned medium (n = 16) or framycetin gauze dressing only (n = 16) applied every three days for up to eight weeks, following which the ulcer size, adverse reactions and complications if any were monitored weekly. Results Healing percentage increased each week in all groups. Statistical differences between groups (P < 0.05) were observed from week 2 onwards for ulcer mean size reduction and from week 3 onwards for ulcer mean depth reduction. There were no adverse reactions or complications. Limitations Off-loading on subjects were not performed. Conclusion Adipose mesenchymal stem cell-conditioned medium is a potential therapeutic agent in the management of chronic plantar ulcer of leprosy.

Effect of stem cell secretome in skin rejuvenation: a narrative review

PURPOSE

Cutaneous aging is an inevitable biological process that develops over time due to cumulative cellular and molecular changes caused by exposure to intrinsic (chronological aging) and extrinsic (photo-aging) factors on the skin. Skin aging is characterized by a decline in the body's capability to sustain senescence, dermal cell apoptosis, and homeostasis. Stem cell secretions (secretome) are defined as the total set of dynamically overlapping paracrine soluble growth factors, cytokines, chemokines, angiogenic factors, extracellular matrix proteins, and antimicrobial peptides known to be responsible for tissue rejuvenation, regeneration, homeostasis, and immunomodulation.

METHODS

In this review, we summarized the molecular and regulatory mechanism of the secretome in preventing the skin aging process, as well as its capacity in inducing skin rejuvenation. Furthermore, we illustrated secretome efficiency as an anti-aging therapeutic strategy based on in vitro and in vivo published studies.

RESULTS

In all reviewed publications, the secretome has been proven to be the most effective treatment for aged skin, capable of reversing the aging process through the action of cytokines, growth factors, and collagen, which are its primary components. The reported mechanism of action involves modulating the signaling pathways of aging and replenishing the skin with collagen, fibronectin, and elastin, ultimately resulting in skin renewal and rejuvenation.

CONCLUSION

In conclusion, compared to available treatments, the secretome shows great promise as an anti-aging therapy.

Delivery of multipotent adult progenitor cells via a functionalized plasma polymerized surface accelerates healing of murine diabetic wounds

Introduction: Stem cell therapies have been investigated as potential treatment modalities for chronic wounds however there has been limited success to date. Multipotent Adult Progenitor Cells (MAPCs©) have been identified as having potential as an allogenic stem cell product due to their high population doubling number and their characteristic dampening of T-cell proliferation. This helps to prevent autoimmunity and graft/cell rejection. Methods: We have developed a dressing, consisting of medical grade silicone coated with a heptylamine plasma polymer, which supports the growth and transfer of MAPCs to skin. To determine if the dressing can deliver functional stem cells into diabetic wounds, they were loaded with MAPCs and then placed over excisional wounds in both normal and diabetic mice. Results and discussion: Accelerated healing was observed in both the normal and diabetic wounds with wound gape being significantly smaller at day 3 when compared to controls. Wound analysis showed that treatment with the MAPC dressings dampened the inflammatory response with reduced numbers of neutrophils and macrophages observed. Additionally, an increase in pro-angiogenic VEGF and CD31 positive endothelial cells was observed indicating improved new blood vessel formation. The MAPC dressings had no effect on fibrosis with collagen I and III being equally affected in both control and treated wounds. Overall, the functionalized MAPC dressings improve healing responses particularly in diabetic mice with impaired healing responses and therefore, show potential for development as an advanced therapeutic approach for the treatment of chronic diabetic wounds.

Emerging Role of Oral Mesenchymal Stem/Stromal Cells and Their Derivates

Mesenchymal stem/stromal cells (MSCs) have fewer ethical, moral, and safety problems in comparison with embryonic stem cells [...].

Tuning the Microenvironment to Create Functionally Distinct Mesenchymal Stromal Cell Spheroids

Mesenchymal stromal cells (MSCs) are under investigation for wound healing and tissue regeneration due to their potent secretome. Compared to monodisperse cells, MSC spheroids exhibit increased cell survival and enhanced secretion of endogenous factors such as vascular endothelial growth factor (VEGF) and prostaglandin E2 (PGE2), two key factors in wound repair. We previously upregulated the proangiogenic potential of homotypic MSC spheroids by manipulating microenvironmental culture conditions. However, this approach depends on the responsiveness of host endothelial cells (ECs)-a limitation when attempting to restore large tissue deficits and for patients with chronic wounds in which ECs are dysfunctional and unresponsive. To address this challenge, we used a Design of Experiments (DOE) approach to engineer functionally distinct MSC spheroids that maximize VEGF production (VEGFMAX) or PGE2 production (PGE2,MAX) while incorporating ECs that could serve as the basic building blocks for vessel formation. VEGFMAX produced 22.7-fold more VEGF with enhanced endothelial cell migration compared to PGE2,MAX, while PGE2,MAX produced 16.7-fold more PGE2 with accelerated keratinocyte migration compared to VEGFMAX. When encapsulated together in engineered protease-degradable hydrogels as a model of cell delivery, VEGFMAX and PGE2,MAX spheroids exhibited robust spreading into the biomaterial and enhanced metabolic activity. The distinct bioactivities of these MSC spheroids demonstrate the highly tunable nature of spheroids and provide a new approach to leverage the therapeutic potential of cell-based therapies.

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.

Effectiveness of Secretome from Human Umbilical Cord Mesenchymal Stem Cells in Gel (10% SM-hUCMSC Gel) for Chronic Wounds (Diabetic and Trophic Ulcer) - Phase 2 Clinical Trial

Background

Chronic wounds carry financial burdens and increase morbidity and mortality, especially in diabetic ulcers and Hansen's Morbus. More than 50% of chronic ulcers are difficult to heal with regular treatment and require new types of therapy such as the use of secretome of human umbilical cord mesenchymal stem cells (SM-hUCMSC).

Methods

This experimental study was carried out to see the effectiveness of using SM-hUCMSC in diabetic ulcers and Hansen's Morbus in four medical facilities (multicentre). The level of active secretion has been measured by default in 10% SM-hUCMSC gel, used as a treatment intervention. The primary outcome is wound healing in terms of the length, width, and extent of the wound. The secondary is the side effects of treatment 2 weeks after administration. Follow-up visits will be scheduled at 1 and 2 weeks post-treatment.

Results

Forty-one chronic ulcers successfully followed the study until the end. In patients with chronic ulcers, the mean ulcer length, width, and area were 1.60 (0,50-13,0), 1.3 (0,5-6,0), and 2.21 (0,25-78) cm square, respectively, before interventions and 1 (0-12), 0,8 (0-6,0), and 1 (0-72) square cm after interventions at the second follow-up. The change between the beginning and end of the intervention was significant (p-value <0.05).

Conclusion

The use of 10% SM-hUCMSC gel topically has been proven effective in accelerating the process of wound healing, especially chronic ulcers with side effects that are not present in this study.

The Potential of MSC-Based Cell-Free Therapy in Wound Healing-A Thorough Literature Review

A wound is an interruption of the normal anatomic structure and function of the skin, which is critical in protecting against foreign pathogens, regulating body temperature and water balance. Wound healing is a complex process involving various phases, including coagulation, inflammation, angiogenesis, re-epithelialization, and re-modeling. Factors such as infection, ischemia, and chronic diseases such as diabetes can compromise wound healing, leading to chronic and refractory ulcers. Mesenchymal stem cells (MSCs) have been used to treat various wound models due to their paracrine activity (secretome) and extracellular vehicles (exosomes) that contain several molecules, including long non-coding RNAs (lncRNAs), micro-RNAs (miRNAs), proteins, and lipids. Studies have shown that MSCs-based cell-free therapy using secretome and exosomes has great potential in regenerative medicine compared to MSCs, as there are fewer safety concerns. This review provides an overview of the pathophysiology of cutaneous wounds and the potential of MSCs-based cell-free therapy in each phase of wound healing. It also discusses clinical studies of MSCs-based cell-free therapies.

Mesenchymal stem cells- an excellent therapeutic agent for cancer

Despite rapid advancement in research of diagnostics and therapeutics, cancer is the most dangerous disease-causing millions of deaths worldwide. Many of the conventional anticancer therapies can even lead to developing resistance to therapy and recurrence of cancer. To find a new, alternative treatment strategy for a variety of ailments scientists and researchers have turned their attention to cell therapies and regenerative medicine. Stem cells are now being researched for their extensive potential application in therapy for several incurable illnesses including cancer. One of the most often employed cell types for regenerative medicine is mesenchymal stem cells. Mesenchymal stem cells (MSCs) are considered a promising source of stem cells in personalized cell-based therapies. The inherent tumor tropic and immune-modulatory properties of MSCs can be used to target cancer cells. This review aims to focus on the anticancer properties of MSCs and their effect on different signaling pathways. Later on, we discuss the advantages of engineered MSCs over non-engineered MSCsin cancer therapy.

Electrosprayed Mesenchymal Stromal Cell Extracellular Matrix Nanoparticles Accelerate Cellular Wound Healing and Reduce Gram-Negative Bacterial Growth

Treatments for acute respiratory distress syndrome are still unavailable, and the prevalence of the disease has only increased due to the COVID-19 pandemic. Mechanical ventilation regimens are still utilized to support declining lung function but also contribute to lung damage and increase the risk for bacterial infection. The anti-inflammatory and pro-regenerative abilities of mesenchymal stromal cells (MSCs) have shown to be a promising therapy for ARDS. We propose to utilize the regenerative effects of MSCs and the extracellular matrix (ECM) in a nanoparticle. Our mouse MSC (MMSC) ECM nanoparticles were characterized using size, zeta potential, and mass spectrometry to evaluate their potential as pro-regenerative and antimicrobial treatments. The nanoparticles had an average size of 273.4 nm (±25.6) and possessed a negative zeta potential, allowing them to surpass defenses and reach the distal regions of the lung. It was found that the MMSC ECM nanoparticles are biocompatible with mouse lung epithelial cells and MMSCs, increasing the wound healing rate of human lung fibroblasts while also inhibiting the growth of Pseudomonas aeruginosa, a common lung pathogen. Our MMSC ECM nanoparticles display characteristics of healing injured lungs while preventing bacterial infection, which can increase recovery time.

Is mandible derived mesenchymal stromal cells superior in proliferation and regeneration to long bone-derived mesenchymal stromal cells?

Mesenchymal stromal cells (MSCs) are cells with the characteristic ability of self-renewal along with the ability to exhibit multilineage differentiation. Bone marrow (BM) is the first tissue in which MSCs were identified and BM-MSCs are most commonly used among various MSCs in clinical settings. MSCs can stimulate and promote osseous regeneration. Due to the difference in the development of long bones and craniofacial bones, the mandibular-derived MSCs (M-MSCs) have distinct differentiation characteristics as compared to that of long bones. Both mandibular and long bone-derived MSCs are positive for MSC-associated markers such as CD-73, -105, and -106, stage-specific embryonic antigen 4 and Octamer-4, and negative for hematopoietic markers such as CD-14, -34, and -45. As the M-MSCs are derived from neural crest cells, they have embryogenic cells which promote bone repair and high osteogenic potential. In vitro and in vivo animal-based studies demonstrate a higher rate of proliferation and high osteogenic potential for M-MSCs as compared to long-bones MSCs, but in vivo studies in human subjects are lacking. The BM-MSCs have their advantages and limitations. M-MSCs may be utilized as an alternative source of MSCs which can be utilized for tissue engineering and promoting the regeneration of bone. M-MSCs may have potential advantages in the repair of craniofacial or orofacial defects. Considering the utility of M-MSCs in the field of orthopaedics, we have discussed various unresolved questions, which need to be explored for their better utility in clinical practice.

Extracellular Vesicles Secreted by TGF-β1-Treated Mesenchymal Stem Cells Promote Fracture Healing by SCD1-Regulated Transference of LRP5

Bone fracture repair is a multiphased regenerative process requiring paracrine intervention throughout the healing process. Mesenchymal stem cells (MSCs) play a crucial role in cell-to-cell communication and the regeneration of tissue, but their transplantation is difficult to regulate. The paracrine processes that occur in MSC-derived extracellular vesicles (MSC-EVs) have been exploited for this study. The primary goal was to determine whether EVs secreted by TGF-β1-stimulated MSCs (MSCTGF-β1-EVs) exhibit greater effects on bone fracture healing than EVs secreted by PBS-treated MSCs (MSCPBS-EVs). Our research was conducted using an in vivo bone fracture model and in vitro experiments, which included assays to measure cell proliferation, migration, and angiogenesis, as well as in vivo and in vitro gain/loss of function studies. In this study, we were able to confirm that SCD1 expression and MSC-EVs can be induced by TGF-β1. After MSCTGF-β1-EVs are transplanted in mice, bone fracture repair is accelerated. MSCTGF-β1-EV administration stimulates human umbilical vein endothelial cell (HUVEC) angiogenesis, proliferation, and migration in vitro. Furthermore, we were able to demonstrate that SCD1 plays a functional role in the process of MSCTGF-β1-EV-mediated bone fracture healing and HUVEC angiogenesis, proliferation, and migration. Additionally, using a luciferase reporter assay and chromatin immunoprecipitation studies, we discovered that SREBP-1 targets the promoter of the SCD1 gene specifically. We also discovered that the EV-SCD1 protein could stimulate proliferation, angiogenesis, and migration in HUVECs through interactions with LRP5. Our findings provide evidence of a mechanism whereby MSCTGF-β1-EVs enhance bone fracture repair by regulating the expression of SCD1. The use of TGF-β1 preconditioning has the potential to maximize the therapeutic effects of MSC-EVs in the treatment of bone fractures.

Tissue-mimetic culture enhances mesenchymal stem cell secretome capacity to improve regenerative activity of keratinocytes and fibroblasts in vitro

Mesenchymal stem/stromal cells (MSCs) are a heterogenous population of multipotent and highly secretory cells currently being investigated in the field of wound healing for their ability to augment tissue responses. The adaptive response of MSC populations to the rigid substrate of current 2D culture systems has been considered to result in a deterioration of regenerative 'stem-like' properties. In this study, we characterise how the improved culture of adipose-derived mesenchymal stem cells (ASCs) within a tissue-mimetic 3D hydrogel system, that is mechanically similar to native adipose tissue, enhances their regenerative capabilities. Notably, the hydrogel system contains a porous microarchitecture that permits mass transport, enabling efficient collection of secreted cellular compounds. By utilising this 3D system, ASCs retained a significantly higher expression of ASC 'stem-like' markers while demonstrating a significant reduction in senescent populations, relative to 2D. Additionally, culture of ASCs within the 3D system resulted in enhanced secretory activity with significant increases in the secretion of proteinaceous factors, antioxidants and extracellular vesicles (EVs) within the conditioned media (CM) fraction. Lastly, treatment of wound healing cells, keratinocytes (KCs) and fibroblasts (FBs), with ASC-CM from the 2D and 3D systems resulted in augmented functional regenerative activity, with ASC-CM from the 3D system significantly increasing KC and FB metabolic, proliferative and migratory activity. This study demonstrates the potential beneficial role of MSC culture within a tissue-mimetic 3D hydrogel system that more closely mimics native tissue mechanics, and subsequently how the improved phenotype augments secretory activity and potential wound healing capabilities of the MSC secretome.

An overview of the current advances in the treatment of inflammatory diseases using mesenchymal stromal cell secretome

The growing interest in mesenchymal stromal cell (MSC) therapy has been leading to the utilization of its therapeutic properties in a variety of inflammatory diseases. The clinical translation of the related research from bench to bedside is cumbersome due to some obvious limitations of cell therapy. It is evident from the literature that the MSC secretome components mediate their wide range of functions. Cell-free therapy using MSC secretome is being considered as an emerging and promising area of biotherapeutics. The secretome mainly consists of bioactive factors, free nucleic acids, and extracellular vesicles. Constituents of the secretome are greatly influenced by the cell's microenvironment. The broad array of immunomodulatory properties of MSCs are now being employed to target inflammatory diseases. This review focuses on the emerging MSC secretome therapies for various inflammatory diseases. The mechanism of action of the various anti-inflammatory factors is discussed. The potential of MSC secretome as a viable anti-inflammatory therapy is deliberated.

Strategies to counteract adverse remodeling of vascular graft: A 3D view of current graft innovations

Vascular grafts are widely used for vascular surgeries, to bypass a diseased artery or function as a vascular access for hemodialysis. Bioengineered or tissue-engineered vascular grafts have long been envisioned to take the place of bioinert synthetic grafts and even vein grafts under certain clinical circumstances. However, host responses to a graft device induce adverse remodeling, to varied degrees depending on the graft property and host's developmental and health conditions. This in turn leads to invention or failure. Herein, we have mapped out the relationship between the design constraints and outcomes for vascular grafts, by analyzing impairment factors involved in the adverse graft remodeling. Strategies to tackle these impairment factors and counteract adverse healing are then summarized by outlining the research landscape of graft innovations in three dimensions-cell technology, scaffold technology and graft translation. Such a comprehensive view of cell and scaffold technological innovations in the translational context may benefit the future advancements in vascular grafts. From this perspective, we conclude the review with recommendations for future design endeavors.

Cellular Aging Secretes: a Comparison of Bone-Marrow-Derived and Induced Mesenchymal Stem Cells and Their Secretome Over Long-Term Culture

Mesenchymal stem cells (MSCs) hold promising therapeutic potential in several clinical applications, mainly due to their paracrine activity. The implementation of future secretome-based therapeutic strategies requires the use of easily accessible MSCs sources that provide high numbers of cells with homogenous characteristics. MSCs obtained from induced pluripotent stem cells (iMSCs) have been put forward as an advantageous alternative to the gold-standard tissue sources, such as bone marrow (BM-MSCs). In this study, we aimed at comparing the secretome of BM-MSCs and iMSCs over long-term culture. For that, we performed a broad characterization of both sources regarding their identity, proteomic secretome analysis, as well as replicative senescence and associated phenotypes, including its effects on MSCs secretome composition and immunomodulatory action. Our results evidence a rejuvenated phenotype of iMSCs, which is translated into a superior proliferative capacity before the induction of replicative senescence. Despite this significant difference between iMSCs and BM-MSCs proliferation, both untargeted and targeted proteomic analysis revealed a similar secretome composition for both sources in pre-senescent and senescent states. These results suggest that shifting from the use of BM-MSCs to a more advantageous source, like iMSCs, may yield similar therapeutic effects as identified over the past years for this gold-standard MSC source.

Combination Effect of Rotator Cuff Repair with Secretome-hypoxia MSCs Ameliorates TNMD, RUNX2, and Healing Histology Score in Rotator Cuff Tear Rats

Objectives

In order to treat a rat model of rotator cuff rupture, this work concentrated on the expression of TNMD and RUNX2, followed by rotator cuff repair and secretome-hMSCs.

Methods

A total of thirty 10-weeks-old male Sprague-Dawley rats were separated into five groups randomly, RC on week 0, lesion treated with a rotator cuff repair and saline (RC + NaCl group, n = 6) for 2 and 8 weeks, and lesion treated with a rotator cuff repair and secretome-hMSCs (RC + secretome-hMSC group, n = 6) for 2 and 8 weeks. The supraspinatus and infraspinatus muscle-tendon units were obtained for histological and biomechanical investigation at 0, 2 and 8 weeks following injury.

Results

The findings showed that, in comparison with the RC + NaCl group, secretome-hMSCs significantly improved tendon repair by upregulating TNMD and RUNX2 expression and histology score.

Conclusion

Combining Secretome-hypoxia MSCs with RC healing may help rats with rotator cuff tears.

Secretome of Young Mesenchymal Stromal Cells Rejuvenates Aged Mesenchymal Stromal Cells by Normalizing Their Phenotype and Restoring Their Differentiation Profile

During aging, the proliferation and differentiation ability of mesenchymal stem/stromal cells (MSCs) gets affected, and hence, aged MSCs are not preferred for regenerative purposes. Rapid identification of aging-associated changes within MSCs and the mechanistic pathways involved are necessary to determine optimal cell sources to treat musculoskeletal disorders in older patients. In the present study, we have identified a set of phenotypic markers, namely downregulated expression of CD90 and upregulated expression of CD45, as age-defining markers for the bone marrow-derived MSCs. We also show that these phenotypic changes in aged MSCs correlate with their aging-mediated differentiation defects. We find that oxidative stress signaling leading to the activation of nuclear factor kappa B (NF-κB) plays an essential role in altering the phenotype and differentiation ability of the aged MSCs. We further show that treatment of aged MSCs with the conditioned medium (CM) derived from young MSCs (young-CM) restored their phenotype and differentiation potential to the young-like by ameliorating activation of NF-κB signaling in them. Similar changes could also be achieved by using an inhibitor of NF-κB signaling, showing that oxidative stress-induced NF-κB activation is the causative factor in the aging of MSCs. Additionally, we show that treating young MSCs with hydrogen peroxide mimics all the aging-mediated changes in them, underscoring the involvement of oxidative stress in the aging of MSCs. Overall, our data suggest that the altered expression of CD90 and CD45 surface markers can be used as a primary screen to identify the onset of aging in the MSCs, which can be quickly reversed by their in vitro treatment with young-CM or NF-κB inhibitor. Our study also puts the phenotypic characterization of MSCs in a clinical perspective.

Sustainable Production and Activity Determination of Serum-Free Conditioned Medium from Menstrual Blood-Derived Endometrial Stem Cells

Mesenchymal stem cells (MSCs) have exhibited great potential as a regenerative medicine, and MSC-derived paracrine effects, mainly including the secretion of various bioactive factors, play critical roles in MSC-based therapies. MSC-derived serum-free conditioned medium (MSC-CM) is defined as the secretome of MSC-derived bioactive factors and is considered a new cell-free therapeutic agent for disease treatment. However, the MSC-CM used in previous studies was prepared by a nearly disposable method that the MSCs were discarded after preparing MSC-CM, and the preparation time was variable; simultaneously, the viability changes of MSCs after MSC-CM preparation are still unknown. Therefore, this study takes MenSCs as a research project and aims to explore the suitable period of sustainable MenSC-CM preparation rather than using a disposable method. As expected, our results confirmed that MenSC-CM improves viability of both naïve targeted cells and H₂O₂-injured targeted cells, and suggested that 36 h is suitable for sustainable MenSC-CM preparation in which the angiogenic factors almost reach to the peak. Simultaneously, the MenSCs used to prepare the MenSC-CM for 36 h also maintained preferable cell viability and could be sustainably used for further MenSC-CM preparation. Moreover, the in vivo results further confirmed the improvement of MenSC-CM on promoting skin wound healing. Consequently, our results not only provide support for optimizing MSC-CM sustainable preparation based on various MSCs but also promote the comprehensive application of MenSCs in the clinic.

Secretome from human adipose-derived mesenchymal stem cells promotes blood vessel formation and pericyte coverage in experimental skin repair

Human adipose tissue-derived stem cells (hASC) secretome display various therapeutically relevant effects in regenerative medicine, such as induction of angiogenesis and tissue repair. The benefits of hASC secretome are primarily orchestrated by trophic factors that mediate autocrine and paracrine effects in host cells. However, the composition and the innate characteristics of hASC secretome can be highly variable depending on the culture conditions. Here, we evaluated the combined effect of serum-free media and hypoxia preconditioning on the hASCs secretome composition and biological effects on angiogenesis and wound healing. The hASCs were cultured in serum-free media under normoxic (NCM) or hypoxic (HCM) preconditioning. The proteomic profile showed that pro- and anti-antiangiogenic factors were detected in NCM and HCM secretomes. In vitro studies demonstrated that hASCs secretomes enhanced endothelial proliferation, survival, migration, in vitro tube formation, and in vivo Matrigel plug angiogenesis. In a full-thickness skin-wound mouse model, injection of either NCM or HCM significantly accelerated the wound healing. Finally, hASC secretomes were potent in increasing endothelial density and vascular coverage of resident pericytes expressing NG2 and nestin to the lesion site, potentially contributing to blood vessel maturation. Overall, our data suggest that serum-free media or hypoxic preconditioning enhances the vascular regenerative effects of hASC secretome in a preclinical wound healing model.

Cellular expansion of MSCs: Shifting the regenerative potential

Mesenchymal-derived stromal or progenitor cells, commonly called "MSCs," have attracted significant clinical interest for their remarkable abilities to promote tissue regeneration and reduce inflammation. Recent studies have shown that MSCs' therapeutic effects, originally attributed to the cells' direct differentiation capacity into the tissue of interest, are largely driven by the biomolecules the cells secrete, including cytokines, chemokines, growth factors, and extracellular vesicles containing miRNA. This secretome coordinates upregulation of endogenous repair and immunomodulation in the local microenvironment through crosstalk of MSCs with host tissue cells. Therapeutic applications for MSCs and their secretome-derived products often involve in vitro monolayer expansion. However, consecutive passaging of MSCs significantly alters their therapeutic potential, inducing a broad shift from a pro-regenerative to a pro-inflammatory phenotype. A consistent by-product of in vitro expansion of MSCs is the onset of replicative senescence, a state of cell arrest characterized by an increased release of proinflammatory cytokines and growth factors. However, little is known about changes in the secretome profile at different stages of in vitro expansion. Some culture conditions and bioprocessing techniques have shown promise in more effectively retaining the pro-regenerative and anti-inflammatory MSC phenotype throughout expansion. Understanding how in vitro expansion conditions influence the nature and function of MSCs, and their associated secretome, may provide key insights into the underlying mechanisms driving these alterations. Elucidating the dynamic and diverse changes in the MSC secretome at each stage of in vitro expansion is a critical next step in the development of standardized, safe, and effective MSC-based therapies.

Engineering Human Mesenchymal Bodies in a Novel 3D-Printed Microchannel Bioreactor for Extracellular Vesicle Biogenesis

Human Mesenchymal Stem Cells (hMSCs) and their derived products hold potential in tissue engineering and as therapeutics in a wide range of diseases. hMSCs possess the ability to aggregate into "spheroids", which has been used as a preconditioning technique to enhance their therapeutic potential by upregulating stemness, immunomodulatory capacity, and anti-inflammatory and pro-angiogenic secretome. Few studies have investigated the impact on hMSC aggregate properties stemming from dynamic and static aggregation techniques. hMSCs' main mechanistic mode of action occur through their secretome, including extracellular vesicles (EVs)/exosomes, which contain therapeutically relevant proteins and nucleic acids. In this study, a 3D printed microchannel bioreactor was developed to dynamically form hMSC spheroids and promote hMSC condensation. In particular, the manner in which dynamic microenvironment conditions alter hMSC properties and EV biogenesis in relation to static cultures was assessed. Dynamic aggregation was found to promote autophagy activity, alter metabolism toward glycolysis, and promote exosome/EV production. This study advances our knowledge on a commonly used preconditioning technique that could be beneficial in wound healing, tissue regeneration, and autoimmune disorders.

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.

Paracrine Effects of Mesenchymal Stem Cells in Ischemic Stroke: Opportunities and Challenges

It is well acknowledged that neuroprotective effects of transplanted mesenchymal stem cells (MSCs) in ischemic stroke are attributed to their paracrine-mediated actions or bystander effects rather than to cell replacement in infarcted areas. This therapeutic plasticity is due to MSCs' ability to secrete a broad range of bioactive molecules including growth factors, trophic factors, cytokines, chemokines, and extracellular vesicles, overall known as the secretome. The secretome derivatives, such as conditioned medium (CM) or purified extracellular vesicles (EVs), exert remarkable advantages over MSC transplantation in stroke treating. Here, in this review, we used published information to provide an overview on the secretome composition of MSCs, underlying mechanisms of therapeutic effects of MSCs, and preclinical studies on MSC-derived products application in stroke. Furthermore, we discussed current advantages and challenges for successful bench-to-bedside translation.

Locally injected Mesenchymal Stem Cells optimize angiogenesis by regulating VEGF and CD31 expression in duodenal perforation

Background

Duodenal perforation is considered as one of gastrointestinal emergency with high morbidity and mortality rate. The MSCs have the ability to improve wound healing by releasing several growth factors and anti-inflammatory cytokines to promote the angiogenesis process. This study aimed to investigate the role of MSCs in duodenal perforation wound healing.

Methods

MSCs were isolated from rat umbilical cord and injected into duodenal wound site at doses of 1.5x10 [(Putra et al., 2018) 66 cells for T1 group and 3x10 [(Putra et al., 2018) 66 cells for T2 group. The control group was treated by local injection of normal saline. The VEGF levels were measured by Western blot, while CD31 expression was analyzed using immunohistochemistry staining. All examinations were assessed on days 3 and 7.

Results

Results showed a significant increase in VEGF and CD31 expression on days 3 and 7 (p < 0,05). The VEGF level was significantly decreased on day 7 compared to day 3.

Conclusion

The administration of MSCs improved the angiogenesis process in duodenal perforation by enhancing VEGF and CD31 expression.

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Duodenal perforation is considered as one of gastrointestinal emergency with high morbidity and mortality rate.

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The MSCs have the ability to improve wound healing by releasing several growth factors and anti-inflammatory cytokines to promote the angiogenesis process.

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This study aimed to investigate the role of MSCs in duodenal perforation wound healing.

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Results showed a significant increase in VEGF and CD31 expression on days 3 and 7.

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The administration of MSCs improved the angiogenesis process in duodenal perforation.