Influence of age on stem cells depends on the sex of the bone marrow donor

Therapeutic potential of dedifferentiated fat cells in a rat model of osteoarthritis of the knee

Introduction

Mature adipocyte-derived dedifferentiated fat cells (DFATs) represent a subtype of multipotent cells that exhibit comparable phenotypic and functional characteristics to adipose-derived stem cells (ASCs). In this study, we assessed the chondroprotective properties of intra-articularly administrated DFATs in a rat model of osteoarthritis (OA). We also investigated in vitro the expression of anti-inflammatory and chondroprotective genes in DFATs prepared from the infrapatellar fat pad (IFP) and subcutaneous adipose-tissue (SC) of human origin.

Methods

In the cell transplantation experiment, rats were assigned to the DFAT and Control group (n = 10 in each group) and underwent anterior cruciate ligament transection (ACLT) accompanied by medial meniscus resection (MMx) to induce OA. One week later, they received intra-articular injections of 1 × 106 DFATs (DFAT group) or PBS (control group) four times, with a weekly administration frequency. Macroscopic and microscopic evaluations were conducted five weeks post-surgery. In the in vitro experiments. DFATs derived from the IFP (IFP-DFATs) and SC (SC-DFATs) were prepared from donor-matched tissue samples (n = 3). The gene expression of PTGS2, TNFAIP6, PRG4, BMP2, and BMP6 under TNF-α or IFN-γ stimulation in these cells was evaluated using RT-PCR. Furthermore, the effect of co-culturing synovial fibroblasts with DFATs on the gene expression of ADAMTS4 and IL-6 were evaluated.

Results

Intra-articular injections of DFATs significantly inhibited cartilage degeneration in the rat OA model induced by ACLT and MMx. RT-PCR analysis revealed that both IFP-DFATs and SC-DFATs upregulated the expression of genes involved in immune regulation, anti-inflammation, and cartilage protection such as PTGS2, TNFAIP6, and BMP2, under stimulation by inflammatory cytokines. Co-culture with DFATs suppressed the expression of ADAMTS4 and IL6 in synovial fibroblasts.

Conclusions

The intra-articular injection of DFATs resulted in chondroprotective effects in the rat OA model. Both SC-DFATs and IFP-DFATs induced the expression of anti-inflammatory and chondroprotective genes in vitro. These results indicate that DFATs appear to possess therapeutic potential in inhibiting cartilage degradation and could serve as a promising cellular resource for OA treatment.

Transplantation of the LRP1high subpopulation of human umbilical cord-derived mesenchymal stem cells improves ovarian function in mice with premature ovarian failure and aged mice

BACKGROUND

Premature ovarian failure (POF) has a profound impact on female reproductive and psychological health. In recent years, the transplantation of umbilical cord-derived mesenchymal stem cells (UC-MSCs) has demonstrated unprecedented potential in the treatment of POF. However, the heterogeneity of human UC-MSCs remains a challenge for their large-scale clinical application. Therefore, it is imperative to identify specific subpopulations within UC-MSCs that possess the capability to improve ovarian function, with the aim of reducing the uncertainty arising from the heterogeneity while achieving more effective treatment of POF.

METHODS

10 × Genomics was performed to investigate the heterogeneity of human UC-MSCs. We used LRP1 as a marker and distinguished the potential therapeutic subpopulation by flow cytometry, and determined its secretory functions. Unsorted UC-MSCs, LRP1high and LRP1low subpopulation was transplanted under the ovarian capsules of aged mice and CTX-induced POF mice, and therapeutic effects was evaluated by assessing hormone levels, estrous cycles, follicle counts, and embryo numbers. RNA sequencing on mouse oocytes and granulosa cells after transplantation was performed to explore the mechanism of LRP1high subpopulation on mouse oocytes and granulosa cells.

RESULTS

We identified three distinct functional subtypes, including mesenchymal stem cells, multilymphoid progenitor cells and trophoblasts. Additionally, we identified the LRP1high subpopulation, which improved ovarian function in aged and POF mice. We elucidated the unique secretory functions of the LRP1high subpopulation, capable of secreting various chemokines, cytokines, and growth factors. Furthermore, LRP1 plays a crucial role in regulating the ovarian microenvironment, including tissue repair and extracellular matrix remodeling. Consistent with its functions, the transcriptomes of oocytes and granulosa cells after transplantation revealed that the LRP1high subpopulation improves ovarian function by modulating the extracellular matrix of oocytes, NAD metabolism, and mitochondrial function in granulosa cells.

CONCLUSION

Through exploration of the heterogeneity of UC-MSCs, we identified the LRP1high subpopulation capable of improving ovarian function in aged and POF mice by secreting various factors and remodeling the extracellular matrix. This study provides new insights into the targeted exploration of human UC-MSCs in the precise treatment of POF.

Stemness properties of SSEA-4+ subpopulation isolated from heterogenous Wharton's jelly mesenchymal stem/stromal cells

Background: High heterogeneity of mesenchymal stem/stromal cells (MSCs) due to different degrees of differentiation of cell subpopulations poses a considerable challenge in preclinical studies. The cells at a pluripotent-like stage represent a stem cell population of interest for many researchers worldwide, which is worthy of identification, isolation, and functional characterization. In the current study, we asked whether Wharton's jelly-derived MSCs (WJ-MSCs) which express stage-specific embryonic antigen-4 (SSEA-4) can be considered as a pluripotent-like stem cell population. Methods: SSEA-4 expression in different culture conditions was compared and the efficiency of two cell separation methods were assessed: Magnetic Activated Cell Sorting (MACS) and Fluorescence Activated Cell Sorting (FACS). After isolation, SSEA-4+ cells were analyzed for the following parameters: the maintenance of the SSEA-4 antigen expression after cell sorting, stem cell-related gene expression, proliferation potential, clonogenicity, secretome profiling, and the ability to form spheres under 3D culture conditions. Results: FACS allowed for the enrichment of SSEA-4+ cell content in the population that lasted for six passages after sorting. Despite the elevated expression of stemness-related genes, SSEA-4+ cells neither differed in their proliferation and clonogenicity potential from initial and negative populations nor exhibited pluripotent differentiation repertoire. SSEA-4+ cells were observed to form smaller spheroids and exhibited increased survival under 3D conditions. Conclusion: Despite the transient expression of stemness-related genes, our findings could not fully confirm the undifferentiated pluripotent-like nature of the SSEA-4+ WJ-MSC population cultured in vitro.

Mesenchymal Stromal Cells Derived from Dental Tissues: Immunomodulatory Properties and Clinical Potential

Mesenchymal stem/stromal cells (MSCs) are multipotent cells located in different areas of the human body. The oral cavity is considered a potential source of MSCs because they have been identified in several dental tissues (D-MSCs). Clinical trials in which cells from these sources were used have shown that they are effective and safe as treatments for tissue regeneration. Importantly, immunoregulatory capacity has been observed in all of these populations; however, this function may vary among the different types of MSCs. Since this property is of clinical interest for cell therapy protocols, it is relevant to analyze the differences in immunoregulatory capacity, as well as the mechanisms used by each type of MSC. Interestingly, D-MSCs are the most suitable source for regenerating mineralized tissues in the oral region. Furthermore, the clinical potential of D-MSCs is supported due to their adequate capacity for proliferation, migration, and differentiation. There is also evidence for their potential application in protocols against autoimmune diseases and other inflammatory conditions due to their immunosuppressive capacity. Therefore, in this review, the immunoregulatory mechanisms identified at the preclinical level in combination with the different types of MSCs found in dental tissues are described, in addition to a description of the clinical trials in which MSCs from these sources have been applied.

Current status of stem cell therapy for type 1 diabetes: a critique and a prospective consideration

Over the past decade, there had been progress in the development of cell therapy for insulin-dependent diabetes. Nevertheless, important hurdles that need to be overcome still remain. Protocols for the differentiation of pluripotent stem cells into pancreatic progenitors or fully differentiated β-cells have been developed. The resulting insulin-producing cells can control chemically induced diabetes in rodents and were the subject of several clinical trials. However, these cells are immunogenic and possibly teratogenic for their transplantation, and an immunoisolation device and/or immunosuppression is needed. A growing number of studies have utilized genetic manipulations to produce immune evasive cells. Evidence must be provided that in addition to the expected benefit, gene manipulations should not lead to any unforeseen complications. Mesenchymal stem/stromal cells (MSCs) can provide a viable alternative. MSCs are widely available from many tissues. They can form insulin-producing cells by directed differentiation. Experimentally, evidence has shown that the transplantation of allogenic insulin-producing cells derived from MSCs is associated with a muted allogeneic response that does not interfere with their functionality. This can be explained by the immunomodulatory functions of the MSC subpopulation that did not differentiate into insulin-producing cells. Recently, exosomes derived from naive MSCs have been used in the experimental domain to treat diabetes in rodents with varying degrees of success. Several mechanisms for their beneficial functions were proposed including a reduction in insulin resistance, the promotion of autophagy, and an increase in the T regulatory population. However, euglycemia was not achieved in any of these experiments. We suggest that exosomes derived from β-cells or insulin-producing cells (educated) can provide a better therapeutic effect than those derived from undifferentiated cells.

Effect of High BMI on Human Bone Marrow-Derived Mesenchymal Stromal Cells

Bone marrow-derived mesenchymal stromal cells (BMSCs) are attractive candidates in tissue engineering and regenerative medicine. Growing evidence has suggested that a high body mass index (BMI) can affect the properties of BMSCs, resulting in a reduced quality of the cells. However, the results are not consistent. Therefore, this study aimed to investigate the influences of high BMI on human BMSCs (hBMSCs). To avoid gender bias, BMSCs from females and males were studied independently. Finally, hBMSCs from 89 females and 152 males were separately divided into the normal BMI group (18.5 kg/m2 ≤ BMI < 25 kg/m2) and the high BMI group (BMI > 25 kg/m2). The cells were analyzed for the colony-forming potential; proliferation capacity; in vitro adipogenic, osteogenic, and chondrogenic differentiation potentials; and the expression of 32 common surface antigens. The results showed that high BMI did not change the number of colonies at passage 1 in females and males. In contrast, significantly reduced colony numbers at passage 4 (P4) were found in both female and male donors with high BMI. The doubling time of hBMSCs was comparable between the normal and the high BMI groups of females and males. Furthermore, the results of trilineage differentiation did not differ between the different BMI groups of males. In females, the high and the normal BMI groups also showed similar adipogenic and chondrogenic differentiation, while osteogenic differentiation was significantly enhanced in the high-BMI group. Regarding the expression of surface antigens, the expressions of CD200 and SSEA4 on hBMSCs were reduced in the high-BMI group of females and males, respectively. In conclusion, high BMI suppressed the clonogenicity of female and male hBMSCs at P4, improved the in vitro osteogenesis of female hBMSCs, and decreased the expressions of CD200 on hBMSCs in females and SSEA4 in males.

Mesenchymal Stromal Cell Secretome Is Affected by Tissue Source and Donor Age

Variation in mesenchymal stromal cell (MSC) function depending on their origin is problematic, as it may confound clinical outcomes of MSC therapy. Current evidence suggests that the therapeutic benefits of MSCs are attributed to secretion of biologically active factors (secretome). However, the effect of donor characteristics on the MSC secretome remains largely unknown. Here, we examined the influence of donor age, sex, and tissue source, on the protein profile of the equine MSC secretome. We used dynamic metabolic labeling with stable isotopes combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify secreted proteins in MSC conditioned media (CM). Seventy proteins were classified as classically secreted based on the rate of label incorporation into newly synthesized proteins released into the extracellular space. Next, we analyzed CM of bone marrow- (n = 14) and adipose-derived MSCs (n = 16) with label-free LC-MS/MS. Clustering analysis of 314 proteins detected across all samples identified tissue source as the main factor driving variability in MSC CM proteomes. Linear modelling applied to the subset of 70 secreted proteins identified tissue-related difference in the abundance of 23 proteins. There was an age-related decrease in the abundance of CTHRC1 and LOX, further validated with orthogonal techniques. Due to the lack of flow cytometry characterization of MSC surface markers, the analysis could not account for the potential effect of cell population heterogeneity. This study provides evidence that tissue source and donor age contribute to differences in the protein composition of MSC secretomes which may influence the effects of MSC therapy.

Promising Markers in the Context of Mesenchymal Stem/Stromal Cells Subpopulations with Unique Properties

The heterogeneity of the mesenchymal stem/stromal cells (MSCs) population poses a challenge to researchers and clinicians, especially those observed at the population level. What is more, the lack of precise evidences regarding MSCs developmental origin even further complicate this issue. As the available evidences indicate several possible pathways of MSCs formation, this diverse origin may be reflected in the unique subsets of cells found within the MSCs population. Such populations differ in specialization degree, proliferation, and immunomodulatory properties or exhibit other additional properties such as increased angiogenesis capacity. In this review article, we attempted to identify such outstanding populations according to the specific surface antigens or intracellular markers. Described groups were characterized depending on their specialization and potential therapeutic application. The reports presented here cover a wide variety of properties found in the recent literature, which is quite scarce for many candidates mentioned in this article. Even though the collected information would allow for better targeting of specific subpopulations in regenerative medicine to increase the effectiveness of MSC-based therapies.

Mesenchymal Stromal Cells: Heterogeneity and Therapeutical Applications

Mesenchymal stromal cells nowadays emerge as a major player in the field of regenerative medicine and translational research. They constitute, with their derived products, the most frequently used cell type in different therapies. However, their heterogeneity, including different subpopulations, the anatomic source of isolation, and high donor-to-donor variability, constitutes a major controversial issue that affects their use in clinical applications. Furthermore, the intrinsic and extrinsic molecular mechanisms underlying their self-renewal and fate specification are still not completely elucidated. This review dissects the different heterogeneity aspects of the tissue source associated with a distinct developmental origin that need to be considered when generating homogenous products before their usage for clinical applications.

Characterization of Human, Ovine and Porcine Mesenchymal Stem Cells from Bone Marrow: Critical In Vitro Comparison with Regard to Humans

For research and clinical use of stem cells, a suitable animal model is necessary. Hence, the aim of this study was to compare human-bone-marrow-derived mesenchymal stem cells (hBMSCs) with those from sheep (oBMSCs) and pigs (pBMSCs). The cells from these three species were examined for their self-renewal potential; proliferation potential; adhesion and migration capacity; adipogenic, osteogenic and chondrogenic differentiation potential; and cell morphology. There was no significant difference between hBMSCs and pBMSCs in terms of self-renewal potential or growth potential. The oBMSCs exhibited a significantly higher doubling time than hBMSCs from passage 7. The migration assay showed significant differences between hBMSCs and pBMSCs and oBMSCs—up to 30 min, hBMSCs were faster than both types and after 60 min faster than pBMSCs. In the adhesion assay, hBMSCs were significantly better than oBMSCs and pBMSCs. When differentiating in the direction of osteogenesis, oBMSCs and pBMSCs have shown a clearer osteogenic potential. In all three species, adipogenesis could only be evaluated qualitatively. The chondrogenic differentiation was successful in hBMSCs and pBMSCs in contrast to oBMSCs. It is also important to note that the cell size of pBMSCs was significantly smaller compared to hBMSCs. Finally, it can be concluded that further comparative studies are needed to draw a clear comparison between hBMSCs and pBMSCs/oBMSCs.

An Intracellular Metabolic Signature as a Potential Donor-Independent Marker of the Osteogenic Differentiation of Adipose Tissue Mesenchymal Stem Cells

This paper describes an untargeted NMR metabolomics study to identify potential intracellular donor-dependent and donor-independent metabolic markers of proliferation and osteogenic differentiation of human adipose mesenchymal stem cells (hAMSCs). The hAMSCs of two donors with distinct proliferating/osteogenic characteristics were fully characterized regarding their polar endometabolome during proliferation and osteogenesis. An 18-metabolites signature (including changes in alanine, aspartate, proline, tyrosine, ATP, and ADP, among others) was suggested to be potentially descriptive of cell proliferation, independently of the donor. In addition, a set of 11 metabolites was proposed to compose a possible donor-independent signature of osteogenesis, mostly involving changes in taurine, glutathione, methylguanidine, adenosine, inosine, uridine, and creatine/phosphocreatine, choline/phosphocholine and ethanolamine/phosphocholine ratios. The proposed signatures were validated for a third donor, although they require further validation in a larger donor cohort. We believe that this proof of concept paves the way to exploit metabolic markers to monitor (and potentially predict) cell proliferation and the osteogenic ability of different donors.