The application of bone marrow mesenchymal stem cells and biomaterials in skeletal muscle regeneration

Evaluation of the management of rotator cuff injuries utilising superparamagnetic iron oxide tracking stem cells

BACKGROUND

The ultrastructure of the tendon-bone interface (TBI) is inherently complex. After arthroscopic reconstruction, it is often replaced by disorganized scar tissue, which increases the risk of re-tearing.Stem cell therapies offer a promising approach to regenerate the original tissue structure and enhance the healing environment. The effectiveness of these therapies depends on understanding the localization, proliferation, and overall behavior of the implanted stem cells. This study aimed to track the distribution of stem cells in a rat model of rotator cuff injury using Magnetic Resonance Imaging (MRI) and superparamagnetic iron oxide nanoparticles (SPIO) and to evaluate the mechanisms and therapeutic effects of stem cell therapy.

METHODS

Adipose-derived mesenchymal stem cells (ADSCs) were isolated and expanded, then labeled with SPIO at an optimized concentration. The visibility of these labeled cells was assessed via MRI, along with evaluations of their viability, potential toxicity, and migration capacity in vitro.For the in vivo study, rats with rotator cuff tears were divided into two groups: a control group that received a PBS injection, and a treatment group that received SPIO-labeled ADSCs (designated as S-A). MRI scans were conducted at 1, 2, and 4 weeks post-surgery, followed by histological analysis after the rats were euthanized. At 8 weeks post-surgery, rats were sacrificed, and their shoulder joints were analyzed biomechanically and histologically to assess the overall treatment efficacy.

RESULTS

SPIO nanoparticles were successfully incorporated into ADSCs, and MRI imaging demonstrated that these SPIO-labeled cells significantly enhanced MRI contrast without affecting cell viability, proliferation, or migration ability. Both MRI and histological analyses confirmed that the implanted stem cells survived and remained localized for at least two weeks. Further histological and biomechanical evaluations indicated that the stem cells facilitated the repair of the TBI. This repair process appeared to be mediated by an increase in M2 macrophage activity within the injured tissue, promoting improved local healing conditions.

CONCLUSION

This study confirms that labeling ADSCs with SPIO nanoparticles is an effective method for tracking these cells in vivo using MRI, providing a non-invasive approach to monitor the repair of injured TBI. Moreover, the localized survival of transplanted stem cells supports their role in enhancing TBI repair by modulating the local inflammatory response.

Protective effects of puerarin combined with bone marrow mesenchymal stem cells on nerve injury in rats with ischemic stroke

BACKGROUND

Bone marrow mesenchymal stem cells (BM-MSCs) transplantation shows promise for treating ischemic stroke, but the ischemic environment that follows cerebral infarction hinders the survival of transplanted cells. We aimed to study the effects of puerarin (Pue) in combination with BM-MSCs on cerebral ischemic injury.

METHODS

After middle cerebral artery occlusion (MCAO) models were prepared by suture-occluded method, rats were randomly allocated to the sham, MCAO, Pue (50 mg/kg), BM-MSCs (2×106), and BM-MSCs+Pue groups. The neurological function, infarct area, levels of inflammation-related factors, brain tissue damage, apoptosis, BrdU, Beclin1, and LC3 levels were then assessed.

RESULTS

Pue and BM-MSCs reduced the modified neurological severity score, cerebral infarction area, and serum inflammation-related factor levels for MCAO rats. Furthermore, Pue and BM-MSCs interventions ameliorated brain tissue damage, and repressed apoptosis of brain tissues in MCAO rats. Moreover, Pue or BM-MSCs enhanced BrdU expression, restrained LC3II/LC3I ratio and Beclin 1 expression in MCAO rats' brain tissues. Importantly, the combination of Pue and BM-MSCs exhibited more pronounced effects on aforementioned outcomes.

CONCLUSION

The combination of Pue and BM-MSCs facilitated the recovery of neurological function in rats after cerebral ischemic damage, and the mechanisms may correlate with the repression of neuronal apoptosis, inflammation, and autophagy.

Effects of intramuscular administration of Platelet-Rich Plasma on denervated muscle after peripheral nerve injury

PURPOSE

After peripheral nerve injury (PNI), prolonged denervation of the target muscle prevents adequate reinnervation even if the nerve is repaired. The aim of this work is to analyze the effect of intramuscular Platelet-Rich Plasma (PRP) in a denervated muscle due to PNI.Materials and.

METHODS

An irreversible PNI was generated in the common peroneal nerve of 80 Wistar rats by nerve resection. Animals were divided into groups: non-treatment (NT), saline (S) and PRP (PRP). 200 uL of saline (S group) and PRP (PRP group) were infiltrated intramuscularly into the tibialis anterior muscle on a weekly basis, from surgery to sacrifice (at 2, 4 and 7 weeks). Muscles were histologically processed for immunofluorescence and Western blotting. Effects on nicotinic acetylcholine receptor (nAChR), satellite cells (SC) and myogenin expression were analyzed. Comparisons were performed by two-way analysis of variance (ANOVA).

RESULTS

PRP had a platelet concentration 1.5-fold higher than blood, without erythrocytes and leukocytes. The PRP group had a higher percentage weight than the S and NT groups (p < 0.05). The levels of nAChRα1 and nAChRε subunit were lower in the PRP group relative to the NT and S (p < 0.05), while the nAChRγ subunit showed an increase in the PRP group (p < 0.05). The activation of SCs was higher in the PRP group compared to NT and S groups (p < 0.05).

CONCLUSION

PRP treatment can modulate NMJ configuration as well as key myogenic regulatory factors in denervated muscle, enhancing SC activation while mitigating muscle atrophy.

Musculoskeletal Organs-on-Chips: An Emerging Platform for Studying the Nanotechnology-Biology Interface

Nanotechnology-based approaches are promising for the treatment of musculoskeletal (MSK) disorders, which present significant clinical burdens and challenges, but their clinical translation requires a deep understanding of the complex interplay between nanotechnology and MSK biology. Organ-on-a-chip (OoC) systems have emerged as an innovative and versatile microphysiological platform to replicate the dynamics of tissue microenvironment for studying nanotechnology-biology interactions. This review first covers recent advances and applications of MSK OoCs and their ability to mimic the biophysical and biochemical stimuli encountered by MSK tissues. Next, by integrating nanotechnology into MSK OoCs, cellular responses and tissue behaviors may be investigated by precisely controlling and manipulating the nanoscale environment. Analysis of MSK disease mechanisms, particularly bone, joint, and muscle tissue degeneration, and drug screening and development of personalized medicine may be greatly facilitated using MSK OoCs. Finally, future challenges and directions are outlined for the field, including advanced sensing technologies, integration of immune-active components, and enhancement of biomimetic functionality. By highlighting the emerging applications of MSK OoCs, this review aims to advance the understanding of the intricate nanotechnology-MSK biology interface and its significance in MSK disease management, and the development of innovative and personalized therapeutic and interventional strategies.

Promoting and accelerating muscle regeneration through cell therapy in a mouse model

Objectives

Skeletal muscle injuries and disorders are universal clinical challenges with direct and indirect mechanisms and notable residual effects, such as prolonged, intense pain and physical disability. Stem cells, an innovative tool for cell therapy for musculoskeletal disorders, specifically promote skeletal muscle regeneration. This study was aimed at investigating the use of mesenchymal stem cells (MSCs) and their differentiated myocytes as a cell-based therapy to promote regeneration in damaged or diseased skeletal muscle.

Methods

Bone marrow mesenchymal stem cells (BM-MSCs) were isolated from the bone marrow of adult mice and grown in tissue culture flasks. The BM-MSCs were positive for CD90 and CD105, and negative for CD45 and CD34. These cells were induced with specific differentiation medium in vitro to differentiate into a skeletal muscle cell lineage over 7 days. Skeletal muscle differentiation was characterized according to morphology through hematoxylin and eosin staining, and scanning electron microscopy. Immunostaining for Myf-6, myosin heavy chain (MHC), and desmin-specific factors for skeletal muscle development-was performed to confirm skeletal muscle differentiation. An in vivo study in a muscle injury model was used to evaluate cell therapy based on naïve stem cells and differentiated myocytes.

Results

Cultured mouse BM-MSCS were positive for CD90 and CD105, and negative for CD45 and CD34. These cells developed into skeletal muscle with strong skeletal muscle differentiation potential, as confirmed by immunohistochemistry for the markers Myf6, MHC, and desmin. The differentiated myocytes showed better repair enhancement than undifferentiated stem cells after transplantations into a mouse model of skeletal muscle atrophy.

Conclusions

Myocytes derived from BM-MSCs may be incorporated into muscular atrophy treatment as a biological strategy for managing skeletal muscle diseases and injuries, thus advancing cell-based clinical treatments.

Hotspots and trends in satellite cell research in muscle regeneration: A bibliometric visualization and analysis from 2010 to 2023

Background

The incidence of muscle atrophy or sports injuries is increasing with time and population aging, thereby attracting considerable attention to muscle generation research. Muscle satellite cells, which play an important role in this process, lack comprehensive literature regarding their use for muscle regeneration. Hence, this study aimed to analyze the hotspots and trends in satellite cell research from 2010 to 2023, providing a reference for muscle regeneration research.

Methods

Studies on satellite cells' role in muscle regeneration from 2010 to 2023 were retrieved from the Web of Science Core Collection. Using CiteSpace and VOSviewer, we analyzed annual publications, authors and co-citing authors, countries and institutions, journals and co-citing journals, co-citing references, and keywords.

Results

From 2010 to 2023, 1468 papers were retrieved, indicating an overall increasing trend in the number of annual publications related to satellite cells in muscle regeneration. The United States had the highest number of publications, while the Institut National de la Santé et de la Recherche Médicale was the institution with the most publications. Among journals, " PloS One" had the highest number of published papers, and "Cell" emerged as the most co-cited journal. A total of 7425 authors were involved, with Michael A. Rudnicki being the author with the highest number of publications and the most co-cited author. The most cited reference was "Satellite cells and the muscle stem cell niche." Among keywords, "satellite cells" was the most common, with "heterogeneity" having the highest centrality. Frontier themes included "Duchenne muscular dystrophy," "skeletal muscle," "in-vivo," "muscle regeneration," "mice," "muscle atrophy," "muscle fibers," "inflammation," " mesenchymal stem cells," and "satellite cell."

Conclusion

This study presents the current status and trends in satellite cell research on muscle regeneration from 2010 to 2023 using bibliometric analyses, providing valuable insights into numerous future research directions.

Causal roles of circulating cytokines in sarcopenia-related traits: a Mendelian randomization study

Background

Epidemiological and experimental evidence suggests that chronic inflammation plays an important role in the onset and progression of sarcopenia. However, there is inconsistent data on the inflammatory cytokines involved in the pathogenesis of sarcopenia. Therefore, we performed a two-sample Mendelian randomization (MR) analysis to explore the causal relationship between circulating cytokines and sarcopenia-related traits.

Methods

The MR analysis utilized genetic data from genome-wide association study that included genetic variations in 41 circulating cytokines and genetic variant data for appendicular lean mass (ALM), hand grip strength, and usual walking pace. Causal associations were primarily explored using the inverse variance-weighted (IVW) method, supplemented by MR-Egger, simple mode, weighted median, and weighted mode analyses. Additionally, sensitivity analyses were also performed to ensure the reliability and stability of the results.

Results

Three cytokines [hepatocyte growth factor (HGF), interferon gamma-induced protein 10 (IP-10), and macrophage colony-stimulating factor (M-CSF)] were positively associated with ALM (β: 0.0221, 95% confidence interval (CI): 0.0071, 0.0372, P= 0.0039 for HGF; β: 0.0096, 95%CI: 4e-04, 0.0189, P= 0.0419 for IP-10; and β: 0.0100, 95%CI: 0.0035, 0.0165, P= 0.0025 for M-CSF). Conversely, higher levels of interleukin-7 (IL-7), monocyte chemotactic protein 3 (MCP-3), and regulated on activation, normal T cell expressed and secreted (RANTES) were associated with decreased hand grip strength (β: -0.0071, 95%CI: -0.0127, -0.0014, P= 0.0140 for IL-7; β: -0.0064, 95%CI: -0.0123, -6e-04, P= 0.0313 for MCP-3; and β: -0.0082, 95%CI: -0.0164, -1e-04, P= 0.0480 for RANTES). Similarly, interleukin 1 receptor antagonist (IL-1RA) was negatively correlated with usual walking pace (β: -0.0104, 95%CI: -0.0195, -0.0013, P= 0.0254). Sensitivity analysis confirmed the robustness of these findings.

Conclusions

Our study provides additional insights into the pivotal role of specific inflammatory cytokines in the pathogenesis of sarcopenia. Further research is required to determine whether these cytokines can be used as targets for the prevention and treatment of sarcopenia.

Differential Responses to Aging Among the Transcriptome and Proteome of Mesenchymal Progenitor Populations

The biological aging of stem cells (exhaustion) is proposed to contribute to the development of a variety of age-related conditions. Despite this, little is understood about the specific mechanisms which drive this process. In this study, we assess the transcriptomic and proteomic changes in 3 different populations of mesenchymal progenitor cells from older (50-70 years) and younger (20-40 years) individuals to uncover potential mechanisms driving stem cell exhaustion in mesenchymal tissues. To do this, we harvested primary bone marrow mesenchymal stem and progenitor cells (MPCs), circulating osteoprogenitors (COP), and adipose-derived stem cells (ADSCs) from younger and older donors, with an equal number of samples from men and women. These samples underwent RNA sequencing and label-free proteomic analysis, comparing the younger samples to the older ones. There was a distinct transcriptomic phenotype in the analysis of pooled older stem cells, suggestive of suppressed proliferation and differentiation; however, these changes were not reflected in the proteome of the cells. Analyzed independently, older MPCs had a distinct phenotype in both the transcriptome and proteome consistent with altered differentiation and proliferation with a proinflammatory immune shift in older adults. COP cells showed a transcriptomic shift to proinflammatory signaling but no consistent proteomic phenotype. Similarly, ADSCs displayed transcriptomic shifts in physiologies associated with cell migration, adherence, and immune activation but no proteomic change with age. These results show that there are underlying transcriptomic changes with stem cell aging that may contribute to a decline in tissue regeneration. However, the proteome of the cells was inconsistently regulated.

MiR-483-3p promotes dental pulp stem cells osteogenic differentiation via the MAPK signaling pathway by targeting ARRB2

Human dental pulp stem cells (DPSCs) have become an important component for bone tissue engineering and regenerative medicine due to their ability to differentiate into osteoblast precursors. Two miRNA chip datasets (GSE138180 and E-MTAB-3077) of DPSCs osteogenic differentiation were analyzed respectively to find the expression of miR-483-3p significantly increased in the differentiated groups. We further confirmed that miR-483-3p continued to overexpress during osteogenic differentiation of DPSCs, especially reaching its peak on the 7th day. Moreover, miR-483-3p could significantly promote the expression of osteogenic markers including RUNX2 and OSX, and activate MAPK signaling pathway by inducing phosphorylation of ERK, p38, and JNK. In addition, as a significant gene within the MAPK signaling pathway, ARRB2 was identified as the target gene of miR-483-3p by bioinformatic prediction and experimental verification. In conclusion, we identified miR-483-3p could promote osteogenic differentiation of DPSCs via the MAPK signaling pathway by targeting ARRB2.

Anti-inflammatory and immunomodulatory effects of mesenchymal stem cell therapy on parasitic drug resistance

INTRODUCTION

The emergence of antiparasitic drug resistance poses a concerning threat to animals and humans. Mesenchymal Stem Cells (MSCs) have been widely used to treat infections in humans, pets, and livestock. Although this is an emerging field of study, the current review outlines possible mechanisms and examines potential synergism in combination therapies and the possible harmful effects of such an approach.

AREAS COVERED

The present study delved into the latest pre-clinical research on utilizing MSCs to treat parasitic infections. As per investigations, the introduction of MSCs to patients grappling with parasitic diseases like schistosomiasis, malaria, cystic echinococcosis, toxoplasmosis, leishmaniasis, and trypanosomiasis has shown a reduction in parasite prevalence. This intervention also alters the levels of both pro- and anti-inflammatory cytokines. Furthermore, the combined administration of MSCs and antiparasitic drugs has demonstrated enhanced efficacy in combating parasites and modulating the immune response.

EXPERT OPINION

Mesenchymal stem cells are a potential solution for addressing parasitic drug resistance. This is mainly because of their remarkable immunomodulatory abilities, which can potentially help combat parasites' resistance to drugs.

Integrated analysis of the DNA methylome and RNA transcriptome during the development of skeletal muscle in Duroc pigs

BACKGROUND

Skeletal muscle development plays a crucial role in yield and quality of pork; however, this process is influenced by various factors. In this study, we employed whole-genome bisulfite sequencing (WGBS) and transcriptome sequencing to comprehensively investigate the longissimus dorsi muscle (LDM), aiming to identify key genes that impact the growth and development of Duroc pigs with different average daily gains (ADGs).

RESULTS

Eight pigs were selected and divided into two groups based on ADGs: H (774.89 g) group and L (658.77 g) group. Each pair of the H and L groups were half-siblings. The results of methylation sequencing revealed 2631 differentially methylated genes (DMGs) involved in metabolic processes, signalling, insulin secretion, and other biological activities. Furthermore, a joint analysis was conducted on these DMGs and the differentially expressed genes (DEGs) obtained from transcriptome sequencing of the same individual. This analysis identified 316 differentially methylated and differentially expressed genes (DMEGs), including 18 DMEGs in promoter regions and 294 DMEGs in gene body regions. Finally, LPAR1 and MEF2C were selected as candidate genes associated with muscle development. Bisulfite sequencing PCR (BSP) and quantitative real-time PCR (qRT-PCR) revealed that the promoter region of LPAR1 exhibited significantly lower methylation levels (P < 0.05) and greater expression levels (P < 0.05) in the H group than in the L group. Additionally, hypermethylation was observed in the gene body region of MEF2C, as was a low expression level, in the H group (P < 0.05).

CONCLUSIONS

These results suggest that the differences in the ADGs of Duroc pigs fed the same diet may be influenced by the methylation levels and expression levels of genes related to skeletal muscle development.

Regeneration of Volumetric Muscle Loss Using MSCs Encapsulated in PRP-Derived Fibrin Microbeads

Volumetric muscle loss (VML) is one of the major types of soft tissue injury frequently encountered worldwide. In case of VML, the endogenous regenerative capacity of the skeletal muscle tissue is usually not sufficient for complete healing of the damaged area resulting in permanent functional musculoskeletal impairment. Therefore, the development of new tissue engineering approaches that will enable functional skeletal muscle regeneration by overcoming the limitations of current clinical treatments for VML injuries has become a critical goal. Platelet-rich plasma (PRP) is an inexpensive and relatively effective blood product with a high concentration of platelets containing various growth factors and cytokines involved in wound healing and tissue regeneration. Due to its autologous nature, PRP has been a safe and widely used treatment option for various wound types for many years. Recently, PRP-based biomaterials have emerged as a promising approach to promote muscle tissue regeneration upon injury. This chapter describes the use of PRP-derived fibrin microbeads as a versatile encapsulation matrix for the localized delivery of mesenchymal stem cells and growth factors to treat VML using tissue engineering strategies.

[A dual-crosslinked injectable hydrogel derived from muscular decellularized matrix promoting myoblasts proliferation and myogenic differentiation]

Objective

To investigate the feasibility of a dual-crosslinked injectable hydrogel derived from acellular musclar matrix (AMM) for promoting myoblasts proliferation and myogenic differentiation.

Methods

Firstly, hyaluronic acid was oxidized with NaIO 4 and methylated to prepare methacrylamidated oxidized hyaluronic acid (MOHA). Then, AMM obtained by washing enzymatically treated muscle tissue was aminolyzed to prepare aminated AMM (AAMM). MOHA hydrogel and AAMM were crosslinked using Schiff based reaction and UV radiation to prepare a dual-crosslinked MOHA/AAMM injectable hydrogel. Fourier transform infrared spectroscopy (FTIR) was used to characterize MOHA, AAMM, and MOHA/AAMM hydrogels. The injectability of MOHA/AAMM hydrogel were evaluated by manual injection, and the gelation performance was assessed by UV crosslinking. The rheological properties and Young's modulus of the hydrogel were examined through mechanical tests. The degradation rate of the hydrogel was assessed by immersing it in PBS. The active components of the hydrogel were verified using immunofluorescence staining and ELISA assay kits. The promotion of cell proliferation by the hydrogel was tested using live/dead staining and cell counting kit 8 (CCK-8) assays after co-culturing with C2C12 myoblasts for 9 days. The effect of the hydrogel on myogenic differentiation was evaluated by immunofluorescence staining and real time quantitative polymerase chain reaction (RT-qPCR).

Results

FTIR spectra confirmed the successful preparation of MOHA/AAMM hydrogel. The hydrogel exhibited good injectability and gelation ability. Compared to MOHA hydrogel, MOHA/AAMM hydrogel exhibited higher viscosity and Young's modulus, a reduced degradation rate, and contained a higher amount of collagen (including collagen type Ⅰ and collagen type Ⅲ) as well as bioactive factors (including epidermal growth factor, fibroblast growth factor 2, vascular endothelial growth factor, and insulin-like growth factor 1). The live/dead cell staining and CCK-8 assay indicated that with prolonged incubation time, there was a significant increase in viable cells and a decrease in dead cells in the C2C12 myoblasts within the MOHA/AAMM hydrogel. Compared with MOHA hydrogel, the difference was significant at each time point ( P<0.05). Immunofluorescence staining and RT-qPCR analysis demonstrated that the deposition of IGF-1 and expression levels of myogenic-related genes (including Myogenin, Troponin T, and myosin heavy chain) in the MOHA/AAMM group were significantly higher than those in the MOHA group ( P<0.05).

Conclusion

The MOHA/AAMM hydrogel prepared based on AMM can promote myoblasts proliferation and myogenic differentiation, providing a novel dual-crosslinked injectable hydrogel for muscle tissue engineering.

Differential responses to aging amongst the transcriptome and proteome of mesenchymal progenitor populations

The biological aging of mesenchymal stem cells is proposed to contribute to the development of a range of musculoskeletal and systemic diseases associated with older adults, such as osteoporosis, sarcopenia, and frailty. Despite this, little is understood about the specific mechanisms which drive this stem cell exhaustion, with most studies evaluating indirect effects of other aging changes, such as DNA damage, senescence, and inflammaging. In this study, we assess the transcriptomic and proteomic changes in three different populations of mesenchymal progenitor cells from older (50-70 years) and younger (20-40 years) individuals to uncover potential mechanisms driving stem cell exhaustion in mesenchymal tissues. To do this, we harvested primary bone marrow mesenchymal stem and progenitor cells (MPCs), circulating osteoprogenitors (COP), and adipose-derived stem cells (ADSCs) from younger and older donors, with an equal number of samples from males and females. These samples underwent RNA sequencing and label-free proteomic analysis, comparing the younger samples to the older ones. There was a distinct transcriptomic phenotype associated with the pooled older stem cells, indicative of suppressed proliferation and differentiation; however, there was no consistent change in the proteome of the cells. Older MPCs had a distinct phenotype in both the transcriptome and proteome, again consistent with altered differentiation and proliferation, but also a pro-inflammatory immune shift in older adults. COP cells showed a strong transcriptomic shift to pro-inflammatory signaling but no consistent proteomic phenotype. Similarly, ADSCs displayed transcriptomic shift in physiologies associated with cell migration, adherence, and immune activation, but no consistent proteomic change with age. These results show that there are underlying transcriptomic changes with stem cell aging that likely contribute to a decline in tissue regeneration; however, contextual factors such as the microenvironment and general health status also have a strong role in this.

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.

Human Bone Marrow-Derived Mesenchymal Stem Cell Applications in Neurodegenerative Disease Treatment and Integrated Omics Analysis for Successful Stem Cell Therapy

Neurodegenerative diseases (NDDs), which are chronic and progressive diseases, are a growing health concern. Among the therapeutic methods, stem-cell-based therapy is an attractive approach to NDD treatment owing to stem cells' characteristics such as their angiogenic ability, anti-inflammatory, paracrine, and anti-apoptotic effects, and homing ability to the damaged brain region. Human bone-marrow-derived mesenchymal stem cells (hBM-MSCs) are attractive NDD therapeutic agents owing to their widespread availability, easy attainability and in vitro manipulation and the lack of ethical issues. Ex vivo hBM-MSC expansion before transplantation is essential because of the low cell numbers in bone marrow aspirates. However, hBM-MSC quality decreases over time after detachment from culture dishes, and the ability of hBM-MSCs to differentiate after detachment from culture dishes remains poorly understood. Conventional analysis of hBM-MSCs characteristics before transplantation into the brain has several limitations. However, omics analyses provide more comprehensive molecular profiling of multifactorial biological systems. Omics and machine learning approaches can handle big data and provide more detailed characterization of hBM-MSCs. Here, we provide a brief review on the application of hBM-MSCs in the treatment of NDDs and an overview of integrated omics analysis of the quality and differentiation ability of hBM-MSCs detached from culture dishes for successful stem cell therapy.

MSCs-derived apoptotic extracellular vesicles promote muscle regeneration by inducing Pannexin 1 channel-dependent creatine release by myoblasts

Severe muscle injury is hard to heal and always results in a poor prognosis. Recent studies found that extracellular vesicle-based therapy has promising prospects for regeneration medicine, however, whether extracellular vesicles have therapeutic effects on severe muscle injury is still unknown. Herein, we extracted apoptotic extracellular vesicles derived from mesenchymal stem cells (MSCs-ApoEVs) to treat cardiotoxin induced tibialis anterior (TA) injury and found that MSCs-ApoEVs promoted muscles regeneration and increased the proportion of multinucleated cells. Besides that, we also found that apoptosis was synchronized during myoblasts fusion and MSCs-ApoEVs promoted the apoptosis ratio as well as the fusion index of myoblasts. Furthermore, we revealed that MSCs-ApoEVs increased the relative level of creatine during myoblasts fusion, which was released via activated Pannexin 1 channel. Moreover, we also found that activated Pannexin 1 channel was highly expressed on the membrane of myoblasts-derived ApoEVs (Myo-ApoEVs) instead of apoptotic myoblasts, and creatine was the pivotal metabolite involved in myoblasts fusion. Collectively, our findings firstly revealed that MSCs-ApoEVs can promote muscle regeneration and elucidated that the new function of ApoEVs as passing inter-cell messages through releasing metabolites from activated Pannexin 1 channel, which will provide new evidence for extracellular vesicles-based therapy as well as improving the understanding of new functions of extracellular vesicles.

Experimental study on co-culture of DiI-labeled rat bone marrow mesenchymal stem cells and neonatal rat cardiomyocytes to induce differentiation into cardiomyocyte-like cells

BACKGROUND: Myocardial infarction is a serious clinical disease with high mortality and poor prognosis. Cardiomyocytes (CMs) have limited regeneration abilities after ischemic injury. Their growth and differentiation can be enhanced by contact co-culture with stem cells. OBJECTIVE: The aim was to study the contact co-culture of Dil-labeled bone marrow mesenchymal stem cells (BMSCs) and CMs for inducing differentiation of CMs from stem cells for treating myocardial infarction. METHODS: After contact co-culture, the differentiation of BMSCs into CMs was analyzed qualitatively by detecting myocardial markers (cardiac troponin T and α-smooth muscle actin) using immunofluorescence and quantitatively using flow cytometry. To examine the mechanism, possible gap junctions between BMSCs and CMs were analyzed by detecting gap junction protein connexin 43 (C×43) expression in BMSCs using immunofluorescence. The functionality of gap junctions was analyzed using dye transfer experiments. RESULTS: The results revealed that BMSCs in contact with CMs exhibited myocardial markers and a significant increase in differentiation rate (P < 0.05); they also proved the existence and function of gap junctions between BMSCs and CMs. CONCLUSIONS: It was shown that contact co-culture can induce Dil-labeled BMSCs to differentiate into CM-like cells and examined the principle of gap junction-mediated signaling pathways involved in inducing stem cells to differentiate into cardiomyocytes.

Young bone marrow transplantation prevents aging-related muscle atrophy in a senescence-accelerated mouse prone 10 model

BACKGROUND

Young bone marrow transplantation (YBMT) has been shown to stimulate vascular regeneration in pathological conditions, including ageing. Here, we investigated the benefits and mechanisms of the preventive effects of YBMT on loss of muscle mass and function in a senescence-associated mouse prone 10 (SAMP10) model, with a special focus on the role of growth differentiation factor 11 (GDF-11).

METHODS

Nine-week-old male SAMP10 mice were randomly assigned to a non-YBMT group (n = 6) and a YBMT group (n = 7) that received the bone marrow of 8-week-old C57BL/6 mice.

RESULTS

Compared to the non-YBMT mice, the YBMT mice showed the following significant increases (all P < 0.05 in 6-7 mice): endurance capacity (>61.3%); grip strength (>37.9%), percentage of slow myosin heavy chain fibres (>14.9-15.9%). The YBMT also increased the amounts of proteins or mRNAs for insulin receptor substrate 1, p-Akt, p-extracellular signal-regulated protein kinase1/2, p-mammalian target of rapamycin, Bcl-2, peroxisom proliferator-activated receptor-γ coactivator (PGC-1α), plus cytochrome c oxidase IV and the numbers of proliferating cells (n = 5-7, P < 0.05) and CD34+/integrin-α7+ muscle stem cells (n = 5-6, P < 0.05). The YMBT significantly decreased the levels of gp91phox, caspase-9 proteins and apoptotic cells (n = 5-7, P < 0.05) in both muscles; these beneficial changes were diminished by the blocking of GDF-11 (n = 5-6, P < 0.05). An administration of mouse recombinant GDF-11 improved the YBMT-mediated muscle benefits (n = 5-6, P < 0.05). Cell therapy with young bone marrow from green fluorescent protein (GFP) transgenic mice exhibited GFP+ myofibres in aged muscle tissues.

CONCLUSIONS

These findings suggest that YBMT can prevent muscle wasting and dysfunction by mitigating apoptosis and proliferation via a modulation of GDF-11 signalling and mitochondrial dysfunction in SAMP10 mice.

The crosstalk between macrophages and bone marrow mesenchymal stem cells in bone healing

Bone injury plagues millions of patients worldwide every year, and it demands a heavy portion of expense from the public medical insurance system. At present, orthopedists think that autologous bone transplantation is the gold standard for treating large-scale bone defects. However, this method has significant limitations, which means that parts of patients cannot obtain a satisfactory prognosis. Therefore, a basic study on new therapeutic methods is urgently needed. The in-depth research on crosstalk between macrophages (Mϕs) and bone marrow mesenchymal stem cells (BMSCs) suggests that there is a close relationship between inflammation and regeneration. The in-depth understanding of the crosstalk between Mϕs and BMSCs is helpful to amplify the efficacy of stem cell-based treatment for bone injury. Only in the suitable inflammatory microenvironment can the damaged tissues containing stem cells obtain satisfactory healing outcomes. The excessive tissue inflammation and lack of stem cells make the transplantation of biomaterials necessary. We can expect that the crosstalk between Mϕs and BMSCs and biomaterials will become the mainstream to explore new methods for bone injury in the future. This review mainly summarizes the research on the crosstalk between Mϕs and BMSCs and also briefly describes the effects of biomaterials and aging on cell transplantation therapy.

Repair of Subacute Intrasubstance Rupture of the Biceps Brachii in a 16-Year-Old Patient

A 16-year-old boy sustained a complete, closed, intrasubstance rupture of both heads of the biceps brachii after a rope swing accident. The patient was managed with open direct repair of the muscle belly. After the surgery, he underwent an extensive physical therapy regimen and regained full range of motion and strength. To our knowledge, this is the youngest reported case of a subacute intrasubstance rupture of the biceps brachii muscle treated surgically in the literature. There is no consensus in the literature regarding the optimal management of these injuries. Given the satisfactory outcome, we suggest that open direct repair of the muscle belly is a reasonable option for the pediatric population.

Comparison of CD146 +/- mesenchymal stem cells in improving premature ovarian failure

BACKGROUND

Mesenchymal stem cells (MSCs) are a heterogeneous group of subpopulations with differentially expressed surface markers. CD146 + MSCs correlate with high therapeutic and secretory potency. However, their therapeutic efficacy and mechanisms in premature ovarian failure (POF) have not been explored.

METHODS

The umbilical cord (UC)-derived CD146 +/- MSCs were sorted using magnetic beads. The proliferation of MSCs was assayed by dye670 staining and flow cytometry. A mouse POF model was established by injection of cyclophosphamide and busulfan, followed by treatment with CD146 +/- MSCs. The therapeutic effect of CD146 +/- MSCs was evaluated based on body weight, hormone levels, follicle count and reproductive ability. Differential gene expression was identified by mRNA sequencing and validated by RT-PCR. The lymphocyte percentage was detected by flow cytometry.

RESULTS

CD146 +/- MSCs had similar morphology and surface marker expression. However, CD146 + MSCs exhibited a significantly stronger proliferation ability. Gene profiles revealed that CD146 + MSCs had a lower levels of immunoregulatory factor expression. CD146 + MSCs exhibited a stronger ability to inhibit T cell proliferation. CD146 +/- MSCs treatment markedly restored FSH and E2 hormone secretion level, reduced follicular atresia, and increased sinus follicle numbers in a mouse POF model. The recovery function of CD146 + MSCs in a reproductive assay was slightly improved than that of CD146 - MSCs. Ovary mRNA sequencing data indicated that UC-MSCs therapy improved ovarian endocrine locally, which was through PPAR and cholesterol metabolism pathways. The percentages of CD3, CD4, and CD8 lymphocytes were significantly reduced in the POF group compared to the control group. CD146 + MSCs treatment significantly reversed the changes in lymphocyte percentages. Meanwhile, CD146 - MSCs could not improve the decrease in CD4/8 ratio induced by chemotherapy.

CONCLUSION

UC-MSCs therapy improved premature ovarian failure significantly. CD146 +/- MSCs both had similar therapeutic effects in repairing reproductive ability. CD146 + MSCs had advantages in modulating immunology and cell proliferation characteristics.

Human umbilical cord-derived mesenchymal stromal cells ameliorate aging-associated skeletal muscle atrophy and dysfunction by modulating apoptosis and mitochondrial damage in SAMP10 mice

Background

Skeletal muscle mass and function losses in aging individuals are associated with quality of life deterioration and disability. Mesenchymal stromal cells exert immunomodulatory and anti-inflammatory effects and could yield beneficial effects in aging-related degenerative disease.

Methods and results

We investigated the efficacy of umbilical cord-derived mesenchymal stromal cells (UC-MSCs) on sarcopenia-related skeletal muscle atrophy and dysfunction in senescence-accelerated mouse prone 10 (SAMP10) mice. We randomly assigned 24-week-old male SAMP10 mice to a UC-MSC treatment group and control group. At 12 weeks post-injection, the UC-MSC treatment had ameliorated sarcopenia-related muscle changes in performance, morphological structures, and mitochondria biogenesis, and it enhanced the amounts of proteins or mRNAs for myosin heavy chain, phospho-AMP-activated protein kinase, phospho-mammalian target of rapamycin, phospho-extracellular signal-regulated kinase1/2, peroxisome proliferator-activated receptor-γ coactivator, GLUT-4, COX-IV, and hepatocyte growth factor in both gastrocnemius and soleus muscles, and it reduced the levels of proteins or mRNAs for cathepsin K, cleaved caspase-3/-8, tumor necrosis factor-α, monocyte chemoattractant protein-1, and gp91^phox mRNAs. The UC-MSC treatment retarded mitochondria damage, cell apoptosis, and macrophage infiltrations, and it enhanced desmin/laminin expression and proliferating and CD34⁺/Integrin α₇⁺ cells in both types of skeletal muscle of the SAMP10 mice. In vitro, we observed increased levels of HGF, PAX-7, and MoyD mRNAs at the 4th passage of UC-MSCs.

Conclusions

Our results suggest that UC-MSCs can improve sarcopenia-related skeletal muscle atrophy and dysfunction via anti-apoptosis, anti-inflammatory, and mitochondrial biogenesis mechanisms that might be mediated by an AMPK-PGC1-α axis, indicating that UC-MSCs may provide a promising treatment for sarcopenia/muscle diseases.

miR-153-3p inhibited osteogenic differentiation of human DPSCs through CBFβ signaling

Dental pulp stem cells (DPSCs) have multilineage differentiation potential and especially show a great foreground in bone regeneration engineering. The mechanism of osteogenic differentiation of DPSCs needs to be explored exactly. As a kind of endogenous and non-coding small RNAs, microRNAs (miRNAs) play an important role in many biological processes including osteogenic differentiation. However, the mechanism of miR-153-3p in osteogenic differentiation of DPSCs is still unknown. Core-binding factors-beta (CBFβ) is a non-DNA-binding factor that combines with the runt-related transcription factor family transcription factors to mediate their DNA-binding affinities, and plays a critical role in regulating osteogenic differentiation. In this study, we explored the mechanisms of miR-153-3p and CBFβ in DPSC osteogenesis. The expression of miR-153-3p and CBFβ was tested under the osteogenic condition, and the influence led by changing the expression of miR-153-3p or CBFβ had also been detected. A luciferase reporter assay confirmed that miR-153-3p directly targeted to CBFβ. The osteogenic markers, alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), and bone morphogenetic protein 2 (BMP2), were tested in protein level or mRNA level. ALP and Alizarin red staining were used to detect the osteoblast activity and mineral deposition. In osteogenic condition, the expressions of CBFβ and osteogenic markers were upregulated, whereas that of miR-153-3p was downregulated. miR-153-3p negatively regulated the osteogenic differentiation, and overexpression of CBFβ could offset the negative effect of miR-153-3p. Our findings provided a novel strategy for DPSC application in treatment of bone deficiencies and facilitated bone regeneration.

A Brief Overview of Global Trends in MSC-Based Cell Therapy

Human mesenchymal stem cells (MSCs), also known as mesenchymal stromal cells or medicinal signaling cells, are important adult stem cells for regenerative medicine, largely due to their regenerative characteristics such as self-renewal, secretion of trophic factors, and the capability of inducing mesenchymal cell lineages. MSCs also possess homing and trophic properties modulating immune system, influencing microenvironment around damaged tissues and enhancing tissue repair, thus offering a broad perspective in cell-based therapies. Therefore, it is not surprising that MSCs have been the broadly used adult stem cells in clinical trials. To gain better insights into the current applications of MSCs in clinical applications, we perform a comprehensive review of reported data of MSCs clinical trials conducted globally. We summarize the biological effects and mechanisms of action of MSCs, elucidating recent clinical trials phases and findings, highlighting therapeutic effects of MSCs in several representative diseases, including neurological, musculoskeletal diseases and most recent Coronavirus infectious disease. Finally, we also highlight the challenges faced by many clinical trials and propose potential solutions to streamline the use of MSCs in routine clinical applications and regenerative medicine.

Stem Cell Therapy: From Idea to Clinical Practice

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

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

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

Three-Dimensional Printing Strategies for Irregularly Shaped Cartilage Tissue Engineering: Current State and Challenges

Although there have been remarkable advances in cartilage tissue engineering, construction of irregularly shaped cartilage, including auricular, nasal, tracheal, and meniscus cartilages, remains challenging because of the difficulty in reproducing its precise structure and specific function. Among the advanced fabrication methods, three-dimensional (3D) printing technology offers great potential for achieving shape imitation and bionic performance in cartilage tissue engineering. This review discusses requirements for 3D printing of various irregularly shaped cartilage tissues, as well as selection of appropriate printing materials and seed cells. Current advances in 3D printing of irregularly shaped cartilage are also highlighted. Finally, developments in various types of cartilage tissue are described. This review is intended to provide guidance for future research in tissue engineering of irregularly shaped cartilage.

Experimental study on co-culture of DiI labeled rat bone marrow mesenchymal stem cells and polycaprolactone film in vitro to make a cell patch

BACKGROUND

In stem cell therapy, due to the lack of an effective carrier, a large number of transplanted stem cells are lost and die. Therefore, finding a suitable carrier has become a further direction of stem cell therapy.

OBJECTIVE

In research on the co-culture of polycaprolactone (PCL) with 1,1'-Dioctadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate (DiI) labeled bone marrow mesenchymal stem cells (BMSCs), we observe the effect of materials on the growth and proliferation of DiI labeled stem cells, and the effect of DiI labeling on patch preparation, so as to find a kind of biomaterial suitable for the growth and proliferation of BMSCs, and find a suitable cell carrier for stem cell therapy of myocardial infarction and in vivo tracing.

METHODS

Clean grade Sprague Dawley rats were selected as experimental objects, BMSCs were isolated and cultured, and the surface markers were identified by flow cytometry. After the BMSCs were cultured for 3 passages, the BMSCs were stained with DiI dye, and the BMSCs DiI and PCL biomaterial film were co-cultured. After 24 hours, the cell growth was observed under fluorescence microscope, and fixed for scanning under electron microscope. The cell proliferation was detected by CCK-8 at 1, 4, 7, 10 days of culture. The measurement data conforming to normal distribution are expressed in the form of mean ± standard deviation (X¯± s). One way ANOVA was used for comparison among groups, LSD analysis was used for pairwise comparison. The difference was statistically significant (P < 0.05).

RESULTS

BMSCs were strongly positive for CD90, CD44H, but negative for CD11b/c, CD45. Under fluorescence microscope, BMSCs DiI showed red light, fusiform or polygonal. Under the scanning electron microscope, the cell patch formed by co-culture of PCL film and DiI-BMSCs had a large number of cells on the surface and normal cell state. CCK-8 assay showed that the OD value on the first day was 0.330 ± 0.025; The OD value was 0.620 ± 0.012 on the 4th day, 1.033 ± 0.144 on the 7th day and 1.223 ± 0.133 on the 10th day. There was significant difference among the time points (P < 0.05).

CONCLUSIONS

The cell patch made of PCL film and DiI labeled BMSCs can survive and proliferate on the surface, so it can be used as a scaffold material for stem cell therapy in vivo.

Bone Marrow-Mesenchymal Stromal Cell Secretome as Conditioned Medium Relieves Experimental Skeletal Muscle Damage Induced by Ex Vivo Eccentric Contraction

Bone marrow-mesenchymal stem/stromal cells (MSCs) may offer promise for skeletal muscle repair/regeneration. Growing evidence suggests that the mechanisms underpinning the beneficial effects of such cells in muscle tissue reside in their ability to secrete bioactive molecules (secretome) with multiple actions. Hence, we examined the effects of MSC secretome as conditioned medium (MSC-CM) on ex vivo murine extensor digitorum longus muscle injured by forced eccentric contraction (EC). By combining morphological (light and confocal laser scanning microscopies) and electrophysiological analyses we demonstrated the capability of MSC-CM to attenuate EC-induced tissue structural damages and sarcolemnic functional properties’ modifications. MSC-CM was effective in protecting myofibers from apoptosis, as suggested by a reduced expression of pro-apoptotic markers, cytochrome c and activated caspase-3, along with an increase in the expression of pro-survival AKT factor. Notably, MSC-CM also reduced the EC-induced tissue redistribution and extension of telocytes/CD34⁺ stromal cells, distinctive cells proposed to play a “nursing” role for the muscle resident myogenic satellite cells (SCs), regarded as the main players of regeneration. Moreover, it affected SC functionality likely contributing to replenishment of the SC reservoir. This study provides the necessary groundwork for further investigation of the effects of MSC secretome in the setting of skeletal muscle injury and regenerative medicine.