Regenerative Medicine Applications of Mesenchymal Stem Cells

Optimal Treatment Parameters for Ultrasound-Stimulated Microbubbles in Upregulating Proliferation and Stemness of Bone Marrow Mesenchymal Stem Cells

OBJECTIVES

Ultrasound-targeted microbubble disruption (UTMD) is a widely used technique to improve the differentiation and proliferation capacity of mesenchymal stem cells (MSCs), but the optimal therapeutic parameters for UTMD are unclear. In this study, we aimed to find the appropriate peak negative pressure (PNP), which is a key parameter for enhancing the stemness properties and proliferation of MSCs.

METHODS

Experiments were performed in UTMD group, ultrasound (US) group under different PNP exposure conditions (0.5, 1.0, and 1.5 MPa), and control group. Apoptosis safety was analyzed by flow cytometry and MSC proliferation was measured at 12, 24, and 36 hours after irradiation by cell counting kit 8. The expression of the stemness genes NANOG, OCT-4, and SOX-2 were determined by enzyme-linked immunosorbent assay (ELISA) or reverse transcription polymerase chain reaction.

RESULTS

The results showed that the 1.5 MPa UTMD-treated group had the highest proliferation capacity of MSCs at 24 hours. ELISA or quantitative reverse transcription polymerase chain reaction results showed that UTMD treatment of the 1.5 MPa group significantly upregulated the expression of the stemness genes NANOG, SOX-2, and OCT-4.

CONCLUSIONS

In conclusion, the appropriate peak PNP value of UTMD was 1.5 MPa, and 1.5 MPa-mediated UTMD group obviously promoted MSCs proliferation and maintained stemness by upregulating the expression of stemness genes.

Osteochondral organoids: current advances, applications, and upcoming challenges

In the realm of studying joint-related diseases, there is a continuous quest for more accurate and representative models. Recently, regenerative medicine and tissue engineering have seen a growing interest in utilizing organoids as powerful tools for studying complex biological systems in vitro. Organoids, three-dimensional structures replicating the architecture and function of organs, provide a unique platform for investigating disease mechanisms, drug responses, and tissue regeneration. The surge in organoid research is fueled by the need for physiologically relevant models to bridge the gap between traditional cell cultures and in vivo studies. Osteochondral organoids have emerged as a promising avenue in this pursuit, offering a better platform to mimic the intricate biological interactions within bone and cartilage. This review explores the significance of osteochondral organoids and the need for their development in advancing our understanding and treatment of bone and cartilage-related diseases. It summarizes osteochondral organoids' insights and research progress, focusing on their composition, materials, cell sources, and cultivation methods, as well as the concept of organoids on chips and application scenarios. Additionally, we address the limitations and challenges these organoids face, emphasizing the necessity for further research to overcome these obstacles and facilitate orthopedic regeneration.

Stem Cell-Based or Cell-Free Gene Therapy in Chondrocyte Regeneration: Synovial Fluid-Derived Mesenchymal Stem Cell Exosomes

BACKGROUND

Cartilage injuries are currently the most prevalent joint disease. Previous studies have emphasized the use of stem cells as the effective treatment for regenerating cartilage damage.

OBJECTIVE

In this study, considering the difficulties of the cellular therapy method, it was hypothesized that human synovial fluid-derived mesenchymal stem cell (hSFMSC) exosomes as a SC source could be used to treat these injuries as a safer and cell-free therapeutic alternative procedure due to its direct relevance to cartilage regeneration. Moreover, this study aimed to determine the miRNA and target genes required for the formation of SC treatment combined with gene therapy in order to reveal the mechanism of cartilage regeneration and increase its effectiveness.

METHODS

MSCs were characterized by flow cytometry, and immunocytochemical and differentiation analyses were done. To characterize functionally isolated exosomes, in vitro uptake analysis was performed. RT-qPCR was used to examine in terms of the advantages of cellular and cell-free therapy, mature human chondroblasts derived by differentiation from hSF-MSCs and human chondrocyte profiles were compared in order to demonstrate the above profile of hSF-MSCs and exosomes isolated from them, and the effectiveness of SC therapy in repairing cartilage damage.

RESULTS

According to our findings, the expression level of hsa-miR-155-5p was found to be considerably higher in chondrocytes differentiated from human synovial fluid MSCs than in mature human chondrocytes. These findings were also supported by the TGF-signalling pathway and chondrogenesis marker genes.

CONCLUSION

It was concluded that hSF-MSCs and exosomes can be used in the treatment of cartilage damage, and hsa-miR-155-5p can be used as a target miRNA in a new gene therapy approach because it increases the therapeutic effect on cartilage damage.

Higher ratios of chondrocyte to mesenchymal stem cells elevate the therapeutic effects of extracellular vesicles harvested from chondrocyte/mesenchymal stem cell co-culture on osteoarthritis in a rat model

Extracellular vesicles (EVs) may have a key therapeutic role and offer an innovative treatment for osteoarthritis (OA). Studies have shown that ratio of MSC/chondrocyte could affect their therapeutic outcomes. Here, we investigate the chondrogenic potential and therapeutic effect of EVs derived from MSCs and chondrocytes in the naïve, chondrogenically primed, and co-culture states to treat OA. EVs are isolated from naïve MSCs (M-EV), chondrogenically primed MSCs (cpM-EV), chondrocytes (C-EV), and co-cultures of chondrocytes plus MSCs at ratios of 1:1 (C/M-EV), 2:1 (2C/M-EV), and 4:1 (4C/M-EV). We characterized the isolated EVs in terms of surface markers, morphology, size, and zeta potential, and evaluated their chondrogenic potential in vitro by qRT-PCR and histological analyses. Next, these EVs were intra-articularly injected into osteoarthritic cartilage of a rat model and assessed by radiography, gait parameters, and histological and immunohistochemical analyses. EVs obtained from chondrocytes co-cultured with MSCs resulted in improved matrix production and functional differentiation. Our research showed that close proximity between the two cell types was essential for this response, and improved chondrogenesis and matrix formation were the outcomes of this interaction in vitro. Furthermore, in the in vivo rat OA model induced by a monoiodoacetate (MIA), we observed recovery from OA by increasing ratio of the C/M-derived EV group compared to the other groups. Our findings show that the increasing chondrocyte ratio to MSC leads to high chondrogenic induction and the therapeutic effect of harvested EVs for cartilage repair.

Mesenchymal Stem Cell-Derived Exosomes are Effective for Radiation Enteritis and Essential for the Proliferation and Differentiation of Lgr5+ Intestinal Epithelial Stem Cells by Regulating Mir-195/Akt/β-Catenin Pathway

BACKGROUND

Radiation enteritis (RE) is a common complication of abdominal or pelvic radiotherapy, which when severe, could be life-threatening. Currently, there are no effective treatments. Studies have shown that mesenchymal stem cells (MSCs)-derived exosomes (MSC-exos) exhibit promising therapeutic effects in inflammatory diseases. However, the specific role of MSC-exos in RE and the regulatory mechanisms remain elusive.

METHODS

In vivo assay was carried out by injecting MSC-exos into the total abdominal irradiation (TAI)-induced RE mouse model. For in vitro assay, Lgr5-positive intestinal epithelial stem cells (Lgr5+ IESC) were extracted from mice, followed by irradiation along with MSC-exos treatment. HE staining was performed to measure histopathological changes. mRNA expression of inflammatory factors TNF-α and IL-6 and stem cell markers LGR5, and OCT4 were quantified by RT-qPCR. EdU and TUNEL staining was performed to estimate cell proliferation and apoptosis. MiR-195 expression in TAI mice and radiation-induced Lgr5+ IESC was tested.

RESULTS

We found that the injection of MSC-exos inhibited inflammatory reaction, increased stem cell marker expression, and maintained intestinal epithelial integrity in TAI mice. Furthermore, MSC-exos treatment increased the proliferation and simultaneously suppressed apoptosis in radiation-stimulated Lgr5+ IESC. MiR-195 expression increased by radiation exposure was decreased by MSC-exos therapy. MiR-195 overexpression facilitated the progress of RE by counteracting the effect of MSC-exos. Mechanistically, the Akt and Wnt/β-catenin pathways inhibited by MSC-exos were activated by miR-195 upregulation.

CONCLUSION

MSC-Exos are effective in treating RE and are essential for the proliferation and differentiation of Lgr5+ IESCs. Moreover, MSC-exos mediates its function by regulating miR-195 Akt β-catenin pathways.

Pluripotent Stem Cell-Derived Hepatocyte-like Cells: Induction Methods and Applications

The development of regenerative medicine provides new options for the treatment of end-stage liver diseases. Stem cells, such as bone marrow mesenchymal stem cells, embryonic stem cells, and induced pluripotent stem cells (iPSCs), are effective tools for tissue repair in regenerative medicine. iPSCs are an appropriate source of hepatocytes for the treatment of liver disease due to their unlimited multiplication capacity, their coverage of the entire range of genetics required to simulate human disease, and their evasion of ethical implications. iPSCs have the ability to gradually produce hepatocyte-like cells (HLCs) with homologous phenotypes and physiological functions. However, how to induce iPSCs to differentiate into HLCs efficiently and accurately is still a hot topic. This review describes the existing approaches for inducing the differentiation of iPSCs into HLCs, as well as some challenges faced, and summarizes various parameters for determining the quality and functionality of HLCs. Furthermore, the application of iPSCs for in vitro hepatoprotective drug screening and modeling of liver disease is discussed. In conclusion, iPSCs will be a dependable source of cells for stem-cell therapy to treat end-stage liver disease and are anticipated to facilitate individualized treatment for liver disease in the future.

A systematic review, umbrella review, and quality assessment on clinical translation of stem cell therapy for knee osteoarthritis: Are we there yet?

BACKGROUND

The success of stem cell therapy for knee osteoarthritis (KOA) in preclinical animal models has accelerated the pace of clinical translation. However, it remains uncertain whether the current scientific evidence supports the clinical application of stem cells in treating KOA. A comprehensive evaluation of the safety and efficacy of stem cell therapies and scientific evidence quality is necessary.

METHODS

Using "stem cells" and "knee osteoarthritis" as the search terms, several databases, including PubMed, Web of Science, Cochrane, Embase, and Clinicaltrials.gov, were searched on August 25, 2022, and updated on February 27, 2023. Clinical studies that reported adverse reactions (ARs) of stem cell therapy in KOA patients were included without limiting the type of studies. Quantitative systematic reviews of stem cell therapy for KOA that conducted meta-analysis were included. Two researchers conducted literature screening and data extraction independently, and the evidence quality was evaluated according to the Institute of Health Economics and AMSTAR 2 criteria.

RESULTS

Fifty clinical studies and 13 systematic reviews/meta-analyses (SRs/MAs) were included. Nineteen ARs were reported in 50 studies, including five knee-related ARs, seven common ARs, and seven other ARs. Some studies reported over 10% prevalence of knee pain (24.5%; 95% CI [14.7%, 35.7%]), knee effusion (12.5%; 95% CI [4.8%, 22.5%]), and knee swelling (11.9%; 95% CI [3.5%, 23.5%]). Additionally, two studies have reported cases of prostate cancer and breast tumors, respectively. However, these two studies suggest that stem cell therapy does not bring significant ARs to patients. SRs/MAs results revealed that stem cell therapy relieved pain in patients over time but did not improve knee function. However, current clinical studies have limited evidence regarding study objectives, test designs, and patient populations. Similarly, SRs/MAs have inadequate evidence regarding study design, risk of bias assessment, outcome description, comprehensive discussion, and potential conflicts of interest.

CONCLUSIONS

The inefficacy of stem cells, the risk of potential complications, and the limited quality of evidence from current studies precluded any recommendation for using stem cell products in patients with KOA. Clinical translation of stem cell therapies remains baseless and should be cautiously approached until more robust evidence is available. PROSPERO registration number: CRD42022355875.

Validation of a color deconvolution method to quantify MSC tri-lineage differentiation across species

Mesenchymal stem cells (MSCs) are a promising candidate for both human and veterinary regenerative medicine applications because of their abundance and ability to differentiate into several lineages. Mesenchymal stem cells are however a heterogeneous cell population and as such, it is imperative that they are unequivocally characterized to acquire reproducible results in clinical trials. Although the tri-lineage differentiation potential of MSCs is reported in most veterinary studies, a qualitative evaluation of representative histological images does not always unambiguously confirm tri-lineage differentiation. Moreover, potential differences in differentiation capacity are not identified. Therefore, quantification of tri-lineage differentiation would greatly enhance proper characterization of MSCs. In this study, a method to quantify the tri-lineage differentiation potential of MSCs is described using digital image analysis, based on the color deconvolution plug-in (ImageJ). Mesenchymal stem cells from three species, i.e., bovine, equine, and porcine, were differentiated toward adipocytes, chondrocytes, and osteocytes. Subsequently, differentiated MSCs were stained with Oil Red O, Alcian Blue, and Alizarin Red S, respectively. Next, a differentiation ratio (DR) was obtained by dividing the area % of the differentiation signal by the area % of the nuclear signal. Although MSCs isolated from all donors in all species were capable of tri-lineage differentiation, differences were demonstrated between donors using this quantitative DR. Our straightforward, simple but robust method represents an elegant approach to determine the degree of MSC tri-lineage differentiation across species. As such, differences in differentiation potential within the heterogeneous MSC population and between different MSC sources can easily be identified, which will support further optimization of regenerative therapies.

Specific features of ex-obese patients significantly influence the functional cell properties of adipose-derived stromal cells

Adipose-derived stromal cells (ADSC) are increasingly used in clinical applications due to their regenerative capabilities. However, ADSC therapies show variable results. This study analysed the effects of specific factors of ex-obese patients on ADSC functions. ADSC were harvested from abdominal tissues (N = 20) after massive weight loss. Patients were grouped according to age, sex, current and maximum body mass index (BMI), BMI difference, weight loss method, smoking and infection at the surgical site. ADSC surface markers, viability, migration, transmigration, sprouting, differentiation potential, cytokine secretion, telomere length and mtDNA copy number were analysed. All ADSC expressed CD73, CD90, CD105, while functional properties differed significantly among patients. A high BMI difference due to massive weight loss was negatively correlated with ADSC proliferation, migration and transmigration, while age, sex or weight loss method had a smaller effect. ADSC from female and younger donors and individuals after weight loss by increase of exercise and diet change had a higher activity. Telomere length, mtDNA copy number, differentiation potential and the secretome did not correlate with patient factors or cell function. Therefore, we suggest that factors such as age, sex, increase of exercise and especially weight loss should be considered for patient selection and planning of regenerative therapies.

The Autophagy Protein Pacer Positively Regulates the Therapeutic Potential of Mesenchymal Stem Cells in a Mouse Model of DSS-Induced Colitis

Mesenchymal stem cells (MSC) have emerged as a promising tool to treat inflammatory diseases, such as inflammatory bowel disease (IBD), due to their immunoregulatory properties. Frequently, IBD is modeled in mice by using dextran sulfate sodium (DSS)-induced colitis. Recently, the modulation of autophagy in MSC has been suggested as a novel strategy to improve MSC-based immunotherapy. Hence, we investigated a possible role of Pacer, a novel autophagy enhancer, in regulating the immunosuppressive function of MSC in the context of DSS-induced colitis. We found that Pacer is upregulated upon stimulation with the pro-inflammatory cytokine TNFα, the main cytokine released in the inflammatory environment of IBD. By modulating Pacer expression in MSC, we found that Pacer plays an important role in regulating the autophagy pathway in this cell type in response to TNFα stimulation, as well as in regulating the immunosuppressive ability of MSC toward T-cell proliferation. Furthermore, increased expression of Pacer in MSC enhanced their ability to ameliorate the symptoms of DSS-induced colitis in mice. Our results support previous findings that autophagy regulates the therapeutic potential of MSC and suggest that the augmentation of autophagic capacity in MSC by increasing Pacer levels may have therapeutic implications for IBD.

Sources, Characteristics, and Therapeutic Applications of Mesenchymal Cells in Tissue Engineering

Tissue engineering (TE) is a therapeutic option within regenerative medicine that allows to mimic the original cell environment and functional organization of the cell types necessary for the recovery or regeneration of damaged tissue using cell sources, scaffolds, and bioreactors. Among the cell sources, the utilization of mesenchymal cells (MSCs) has gained great interest because these multipotent cells are capable of differentiating into diverse tissues, in addition to their self-renewal capacity to maintain their cell population, thus representing a therapeutic alternative for those diseases that can only be controlled with palliative treatments. This review aimed to summarize the state of the art of the main sources of MSCs as well as particular characteristics of each subtype and applications of MSCs in TE in seven different areas (neural, osseous, epithelial, cartilage, osteochondral, muscle, and cardiac) with a systemic revision of advances made in the last 10 years. It was observed that bone marrow-derived MSCs are the principal type of MSCs used in TE, and the most commonly employed techniques for MSCs characterization are immunodetection techniques. Moreover, the utilization of natural biomaterials is higher (41.96%) than that of synthetic biomaterials (18.75%) for the construction of the scaffolds in which cells are seeded. Further, this review shows alternatives of MSCs derived from other tissues and diverse strategies that can improve this area of regenerative medicine.

Exercise, Diet and Sleeping as Regenerative Medicine Adjuvants: Obesity and Ageing as Illustrations

Regenerative medicine uses the biological and medical knowledge on how the cells and tissue regenerate and evolve in order to develop novel therapies. Health conditions such as ageing, obesity and cancer lead to an impaired regeneration ability. Exercise, diet choices and sleeping pattern have significant impacts on regeneration biology via diverse pathways including reducing the inflammatory and oxidative components. Thus, exercise, diet and sleeping management can be optimized towards therapeutic applications in regenerative medicine. It could allow to prevent degeneration, optimize the biological regeneration and also provide adjuvants for regenerative medicine.

Polychromatic Flow Cytometric Analysis of Stromal Vascular Fraction from Lipoaspirate and Microfragmented Counterparts Reveals Sex-Related Immunophenotype Differences

Mesenchymal stem/stromal cells or medicinal signaling cells (MSC)-based therapy holds promise as a beneficial strategy for treating knee OA (osteoarthritis), but there is no standardized protocols nor mechanistic understanding. In order to gain a better insight into the human MSC from adipose tissue applied for autologous OA treatment, we performed extensive comparative immunophenotyping of the stromal vascular fraction from lipoaspirate or microfragmented lipoaspirates by polychromatic flow cytometry and investigated the cellular components considered responsible for cartilage regeneration. We found an enrichment of the regenerative cellular niche of the clinically applied microfragmented stromal vascular fraction. Sex-related differences were observed in the MSC marker expression and the ratio of the progenitor cells from fresh lipoaspirate, which, in female patients, contained a higher expression of CD90 on the three progenitor cell types including pericytes, a higher expression of CD105 and CD146 on CD31^highCD34^high endothelial progenitors as well as of CD73 on supra-adventitialadipose stromal cells. Some of these MSC-expression differences were present after microfragmentation and indicated a differential phenotype pattern of the applied MSC mixture in female and male patients. Our results provide a better insight into the heterogeneity of the adipose MSC subpopulations serving as OA therapeutics, with an emphasis on interesting differences between women and men.

Single-Cell RNA Sequencing of Bone Marrow Mesenchymal Stem Cells from the Elderly People

Background and Objectives

Bone marrow mesenchymal stem cells (BMSCs) show considerable promise in regenerative medicine. Many studies demonstrated that BMSCs cultured in vitro were highly heterogeneous and composed of diverse cell subpopulations, which may be the basis of their multiple biological characteristics. However, the exact cell subpopulations that make up BMSCs are still unknown.

Methods and Results

In this study, we used single-cell RNA sequencing (scRNA-Seq) to divide 6,514 BMSCs into three clusters. The number and corresponding proportion of cells in clusters 1 to 3 were 3,766 (57.81%), 1,720 (26.40%), and 1,028 (15.78%). The gene expression profile and function of the cells in the same cluster were similar. The vast majority of cells expressed the markers defining BMSCs by flow cytometry and gene expression analysis. Each cluster had at least 20 differentially expressed genes (DEGs). We conducted Gene Ontology enrichment analysis on the top 20 DEGs of each cluster and found that the three clusters had different functions, which were related to self-renewal, multilineage differentiation and cytokine secretion, respectively. In addition, the function of the top 20 DEGs of each cluster was checked by the National Center for Biotechnology Information gene database to further verify our hypothesis.

Conclusions

This study indicated that scRNA-Seq can be used to divide BMSCs into different subpopulations, demonstrating the heterogeneity of BMSCs.

The concurrent therapeutic potential of adipose-derived mesenchymal stem cells on Gentamycin-induced hepatorenal toxicity in rats

BACKGROUND

Adipose mesenchymal stem cells (AMSCs) are a type of stem cell employed to repair damaged organs. This study aimed to see how effective AMSCs are at treating gentamycin-induced hepatorenal damage in rats.

METHODS

18 male Wister rats were assigned into three groups; control, Gentamycin (GM), and GM+AMSCs. GM induced hepatorenal toxicity through daily injection (100 mg/kg, i.p.) for eight days. On day 9, AMSC (106 cells/ml/rat) was injected intravenously.

RESULTS

Creatinine, urea, uric acid, AST, ALP, ALT, TNF-, and MDA levels decreased, whereas IL-10, GSH, and CAT levels increased, indicating the therapeutic potency of intravenous injection AMSCs.

CONCLUSION

The current study demonstrated the simultaneous therapeutic efficacy of adipose mesenchymal stem cells on the liver and kidney in the treatment of Gentamycin-induced hepatotoxicity. These data show that AMSCs could be a feasible therapy option for liver and kidney disease.

Exosomes derived from mesenchymal stem cells ameliorate renal fibrosis via delivery of miR-186-5p

Evidence has shown that mesenchymal stem cells' (MSCs) therapy has potential application in treating chronic kidney disease (CKD). In addition, MSCs-derived exosomes can improve the renal function and prevent the progression of CKD. However, the mechanisms by which MSCs-derived exosomes (MSCs-Exo) ameliorate renal fibrosis in CKD remain largely unclear. To mimic an in vitro model of renal fibrosis, rat kidney tubular epithelial cells (NRK52E) were stimulated with transforming growth factor (TGF)-β1. In addition, we established an in vivo model of unilateral ureteric obstruction (UUO)-induced renal fibrosis. Meanwhile, we exploited exosomes derived from MSCs for delivering miR-186-5p agomir into NRK52E cells or kidneys in vitro and in vivo. In this study, we found that level of miR-186-5p was significantly downregulated in TGF-β1-stimulated NRK52E cells and the obstructed kidneys of UUO mice. In addition, miR-186-5p can be transferred from MSCs to NRK52E cells via exosomes. MSCs-delivered miR-186-5p markedly reduced the accumulation of extracellular matrix (ECM) protein, and inhibited epithelial-to-mesenchymal transition (EMT) and apoptosis in TGF-β1-stimulated NRK52E cells. Moreover, exosomal miR-186-5p from MSCs attenuated kidney injury and fibrosis in a UUO mouse model via inhibition of the ECM protein accumulation and EMT process. Meanwhile, dual-luciferase assay showed that miR-186-5p downregulated Smad5 expression via direct binding with the 3'-UTR of Smad5. Collectively then, these findings indicated that exosomal miR-186-5p derived from MSCs could attenuate renal fibrosis in vitro and in vivo by downregulation of Smad5. These findings may help to understand the role of MSCs' exosomes in alleviating renal fibrosis in CKD.

Assessment of Long-Term in vitro Multiplied Human Wharton's Jelly-Derived Mesenchymal Stem Cells prior to Their Use in Clinical Administration

The quantity of mesenchymal stem/stromal cells (MSCs) required for a particular therapy demands their subsequent expansion through ex vivo culture. During in vitro multiplication, they undergo replicative senescence which may alter their genetic stability. Therefore, this study was aimed to analyze cellular, molecular, and chromosomal alterations in Wharton's jelly-derived MSCs (WJ-MSCs) during their in vitro sequential passages, where WJ-MSCs were sequentially passaged up to P14 and cells were evaluated at an interval of P2, P6, P10, and P14. They were examined for their morphology, tumorigenicity, surface markers, stemness markers, DNA damage, chromosomal aberration, and telomere length. We have processed five full-term delivered human umbilical cord samples to obtain WJ-MSCs. Morphological appearance observed at initial stages was small fine spindle-shaped WJ-MSCs which were transformed to flat, long, and broader cells in later passages. The cell proliferation rate was gradually decreased after the 10th passage. WJ-MSCs have expressed stemness markers OCT-4 and NANOG, while they showed high expression of positive surface markers CD90 and CD105 and lower expression of CD34 and CD45. They were non-tumorigenic with slow cellular aging during subsequent passages. There was no chromosomal abnormality up to the 14th passage, while increase in comet score and decrease in telomere length were observed in later passages. Hence, our study suggests that early and middle passaged (less than P10) WJ-MSCs are good candidates for clinical administration for treatment.

Therapeutic mesenchymal stromal stem cells: Isolation, characterization and role in equine regenerative medicine and metabolic disorders

Mesenchymal stromal cells (MSC) have become a popular treatment modality in equine orthopaedics. Regenerative therapies are especially interesting for pathologies like complicated tendinopathies of the distal limb, osteoarthritis, osteochondritis dissecans (OCD) and more recently metabolic disorders. Main sources for MSC harvesting in the horse are bone marrow, adipose tissue and umbilical cord blood. While the acquisition of umbilical cord blood is fairly easy and non-invasive, extraction of bone marrow and adipose tissue requires more invasive techniques. Characterization of the stem cells as a result of any isolation method, is also a crucial step for the confirmation of the cells' stemness properties; thus, three main characteristics must be fulfilled by these cells, namely: adherence, expression of a series of well-defined differentiation clusters as well as pluripotency. EVs, resulting from the paracrine action of MSCs, also play a key role in the therapeutic mechanisms mediated by stem cells; MSC-EVs are thus largely implicated in the regulation of proliferation, maturation, polarization and migration of various target cells. Evidence that EVs alone represent a complex network 0involving different soluble factors and could then reflect biophysical characteristics of parent cells has fuelled the importance of developing highly specific techniques for their isolation and analysis. All these aspects related to the functional and technical understanding of MSCs will be discussed and summarized in this review.

Chronic Leg Ulcers: Are Tissue Engineering and Biomaterials Science the Solution?

Chronic leg ulcers (CLUs) are full thickness wounds that usually occur between the ankle and knee, fail to heal after 3 months of standard treatment, or are not entirely healed at 12 months. CLUs present a considerable burden on patients, subjecting them to severe pain and distress, while healthcare systems suffer immense costs and loss of resources. The poor healing outcome of the standard treatment of CLUs generates an urgent clinical need to find effective solutions for these wounds. Tissue Engineering and Biomaterials Science offer exciting prospects for the treatment of CLUs, using a broad range of skin substitutes or scaffolds, and dressings. In this review, we summarize and discuss the various types of scaffolds used clinically in the treatment of CLUs. Their structure and therapeutic effects are described, and for each scaffold type representative examples are discussed, supported by clinical trials. Silver dressings are also reviewed due to their reported benefits in the healing of leg ulcers, as well as recent studies on new dermal scaffolds, reporting on clinical results where available. We conclude by arguing there is a further need for tissue-engineered products specifically designed and bioengineered to treat these wounds and we propose a series of properties that a biomaterial for CLUs should possess, with the intention of focusing efforts on finding an effective treatment.

Improving Culture Conditions, Proliferation, and Migration of Porcine Mesenchymal Stem Cells on Spinal Cord Contusion Injury Model in vitro

Adipose tissue-derived mesenchymal stem cells (AD-MSCs) are promising for cell therapy in spinal cord injury (SCI). The pig is one of the most approximate models of many human diseases, including SCI. In our study, we selected the optimal conditions for the culture of porcine AD-MSCs and developed an in vitro SCI model based on the culture of cells in injured spinal cord extracts (SCE) 3 days and 6 weeks after SCI. We show that Dulbecco's Modified Eagle Medium (DMEM) with 20% serum content, supplemented with a combination of 5 mM L-ascorbate-2-phosphate and nonessential amino acids, stimulated a typical fibroblast-like morphology and high proliferation of porcine AD-MSCs. SCE caused a higher proliferation of porcine AD-MSCs compared with extracts from an intact spinal cord. The optimal proliferating effect was achieved using rostral 3 days SCE, and proliferation was lower in caudal and central SCE. Porcine AD-MSCs migration to the 3 days and 6 weeks SCE was higher than to an intact one and preferred the rostral SCE, avoiding central and caudal SCE. We also studied 13 cytokines contained in SCE but did not observe any definite relationship between some analyte concentrations and a change in the behavior of AD-MSCs.

Epidrugs: novel epigenetic regulators that open a new window for targeting osteoblast differentiation

Efficient osteogenic differentiation of mesenchymal stem cells (MSCs) is a critical step in the treatment of bone defects and skeletal disorders, which present challenges for cell-based therapy and regenerative medicine. Thus, it is necessary to understand the regulatory agents involved in osteogenesis. Epigenetic mechanisms are considered to be the primary mediators that regulate gene expression during MSC differentiation. In recent years, epigenetic enzyme inhibitors have been used as epidrugs in cancer therapy. A number of studies mentioned the role of epigenetic inhibitors in the regulation of gene expression patterns related to osteogenic differentiation. This review attempts to provide an overview of the key regulatory agents of osteogenesis: transcription factors, signaling pathways, and, especially, epigenetic mechanisms. In addition, we propose to introduce epigenetic enzyme inhibitors (epidrugs) and their applications as future therapeutic approaches for bone defect regeneration.

CdSe quantum dots evaluation in primary cellular models or tissues derived from patients

In recent years quantum dots (QDs) have risen as useful luminescent nanoparticles with multiple applications ranging from laser, image displays and biomedical applications. Here we review and discuss the studies of these nanoparticles in patient derived cellular samples or tissues, including cellular models from iPSCs from patients, biopsied and post-mortem tissue. QD-based multiplexed imaging has been proved to overcome most of the major drawbacks of conventional techniques, exhibiting higher sensitivity, reliability, accuracy and simultaneous labeling of key biomarkers. In this sense, QDs are very promising tools to be further used in clinical applications including diagnosis and therapy approaches. Analyzing the possibilities of these materials in these biological samples gives an overview of the future applications of the nanoparticles in models closer to patients and their specific disease.

Exosomal microRNAs derived from mesenchymal stem cells: cell-to-cell messages

Exosomes are extracellular vesicles characterized by their size, source, release mechanism and contents. MicroRNAs (miRNAs) are single stranded non-coding RNAs transcribed from DNA. Exosomes and miRNAs are widespread in eukaryotic cells, especially in mesenchymal stem cells (MSCs). MSCs are used for tissue regeneration, and also exert paracrine, anti-inflammatory and immunomodulatory effects. However, the use of MSCs is controversial, especially in the presence or after the remission of a tumor, due to their secretion of growth factors and their migration ability. Instead of intact MSCs, MSC-derived compartments or substances could be used as practical tools for diagnosis, follow up, management and monitoring of diseases. Herein, we discuss some aspects of exosomal miRNAs derived from MSCs in the progression, diagnosis and treatment of various diseases. Video Abstract.

Adult mesenchymal stem cells and their exosomes: Sources, characteristics, and application in regenerative medicine

Human mesenchymal stem cells (MSCs) have become a hot topic in the development of cell therapies and bioengineering. All kinds of MSCs are genomic stable and have the self-renewal ability. Main sources of MSCs are bone marrow, adipose tissues, umbilical cord and placental tissues. MSCs can be cultured in many undifferentiated passages to grow into more specialized cells, produce secretory factors and also support trophic functions in the body. Exosomes, derived from MSCs also have great potential in regenerative medicine and tissue engineering. Exosomes are secreted by MSCs and have the same therapeutic potential as their parent cells. MSCs and their exosomes combined with biomaterials can also be more effective in promoting the regeneration of tissues and organs. However, for use of MSCs-exosomes as a clinical agent different MSCs-exosomes have been manufactured and their therapeutics effects demonstrated in clinical studies. But there are still many characteristics which are unknown and many barriers still need to be conquered. In this review, we not only highlighted the characteristics of human MSCs and their exosomes, but also provided their latest therapeutic strategies in regenerative medicine.

Effects of Different Tacrolimus Doses on Adipose-Derived Stem Cells

OBJECTIVES

Tacrolimus is currently one of the most commonly used immunosuppressant agents to prevent rejection in organ transplant. Although modern immunosuppressive agents have been successful, rejection cannot be completely prevented. Therefore, in organ transplant research, additional treatment methods are being investigated, with the most important one being stem cell therapy. In addition to tacrolimus therapy, stem cell therapy is now clinically applicable, with frequency of concomitant use seeming to expand in the future. In this study, the effects of tacrolimus on stem cells were investigated.

MATERIALS AND METHODS

Adipose-derived stem cells were treated with tacrolimus at different doses and time points. We analyzed the effects of changes in stem cell proliferation using MTT analysis. Sox2, Oct3/4, and Nanog protein levels were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to measure stem cell pluripotency capabilities.

RESULTS

Our observations showed that tacrolimus causes changes in stem cell proliferation and pluripotency, with changes dependent on time and dose.

CONCLUSIONS

The dose of tacrolimus and the time of application of stem cells are important in the planning of stem cell therapy in organ transplant.

Proteins and Peptides as Important Modifiers of the Polymer Scaffolds for Tissue Engineering Applications-A Review

Polymer scaffolds constitute a very interesting strategy for tissue engineering. Even though they are generally non-toxic, in some cases, they may not provide suitable support for cell adhesion, proliferation, and differentiation, which decelerates tissue regeneration. To improve biological properties, scaffolds are frequently enriched with bioactive molecules, inter alia extracellular matrix proteins, adhesive peptides, growth factors, hormones, and cytokines. Although there are many papers describing synthesis and properties of polymer scaffolds enriched with proteins or peptides, few reviews comprehensively summarize these bioactive molecules. Thus, this review presents the current knowledge about the most important proteins and peptides used for modification of polymer scaffolds for tissue engineering. This paper also describes the influence of addition of proteins and peptides on physicochemical, mechanical, and biological properties of polymer scaffolds. Moreover, this article sums up the major applications of some biodegradable natural and synthetic polymer scaffolds modified with proteins and peptides, which have been developed within the past five years.

Exosomal miRNAs: novel players in viral infection

Exosomes are secreted nanovesicles that are able to transfer their cargo (such as miRNAs) between cells. To determine to what extent exosomes and exosomal miRNAs are involved in the pathogenesis, progression and diagnosis of viral infections. The scientific literature (PubMed and Google Scholar) was searched from 1970 to 2019. The complex biogenesis of exosomes and miRNAs was reviewed. Exosomes contain both viral and host miRNAs that can be used as diagnostic biomarkers for viral diseases. Viral proteins can alter miRNAs, and conversely miRNAs can alter the host response to viral infections in a positive or negative manner. It is expected that exosomal miRNAs will be increasingly used for diagnosis, monitoring and even treatment of viral infections.

The Current Status of Cell-Based Therapies for Primary Knee Osteoarthritis

There is a growing interest in cell therapy for knee osteoarthritis. This study systematically reviews the current status of cell-based therapies. The authors review treatment modalities, clinical outcomes, and the economics of cell therapy. Inclusion criteria were articles containing cellular therapy, platelet-rich plasma, and knee osteoarthritis in the title. Letters, editorial material, abstracts not published, and manuscripts with incomplete data were excluded. Forty-two articles met these inclusion criteria and were critically reviewed. Cell-based therapy holds promise as a means of restoring deficient local cartilage cell populations. There is no evidence-based information for the use of cell-based therapies in knee osteoarthritis.

The Plasticity of Mesenchymal Stem Cells in Regulating Surface HLA-I

A low surface expression level of human leukocyte antigen class I (HLA-I) ensures that the mesenchymal stem cells (MSCs) escape from the allogeneic recipients' immunological surveillance. Here, we discovered that both transcriptional and synthesis levels of HLA-I in MSCs increased continuously after interferon (IFN)-γ treatment, whereas interestingly, their surface HLA-I expression was downregulated after reaching an HLA-I surface expression peak. Microarray data indicated that the post-transcriptional process plays an important role in the downregulation of surface HLA-I. Further studies identified that IFN-γ-treated MSCs accelerated HLA-I endocytosis through a clathrin-independent dynamin-dependent endocytosis pathway. Furthermore, cells that have self-downregulated surface HLA-I expression elicit a weaker immune response than they previously could. Thus uncovering the plasticity of MSCs in the regulation of HLA-I surface expression would reveal insights into the membrane transportation events leading to the maintenance of low surface HLA-I expression, providing more evidence for selecting and optimizing low-immunogenic MSCs to improve the therapeutic efficiency.

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hESC-MSCs have the plasticity of maintaining low HLA-I expression on cell surface

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hESC-MSCs downregulate the surface HLA-I expression through endocytosis of HLA-I

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hESC-MSCs with lower HLA-I surface expression induce weaker MLR and slighter DTH

Mesenchymal Stem Cells in Renal Fibrosis: The Flame of Cytotherapy

Renal fibrosis, as the fundamental pathological process of chronic kidney disease (CKD), is a pathologic extension of the normal wound healing process characterized by endothelium injury, myofibroblast activation, macrophage migration, inflammatory signaling stimulation, matrix deposition, and remodelling. Yet, the current method of treating renal fibrosis is fairly limited, including angiotensin-converting enzyme inhibition, angiotensin receptor blockade, optimal blood pressure control, and sodium bicarbonate for metabolic acidosis. MSCs are pluripotent adult stem cells that can differentiate into various types of tissue lineages, such as the cartilage (chondrocytes), bone (osteoblasts), fat (adipocytes), and muscle (myocytes). Because of their many advantages like ubiquitous sources, convenient procurement and collection, low immunogenicity, and low adverse effects, with their special identification markers, mesenchymal stem MSC-based therapy is getting more and more attention. Based on the mechanism of renal fibrosis, MSCs mostly participate throughout the renal fibrotic process. According to the latest and overall literature reviews, we aim to elucidate the antifibrotic mechanisms and effects of diverse sources of MSCs on renal fibrosis, assess their efficacy and safety in preliminarily clinical application, answer the controversial questions, and provide novel ideas into the MSC cellular therapy of renal fibrosis.