Unveiling heterogeneity in MSCs: exploring marker-based strategies for defining MSC subpopulations

Single-cell Raman spectroscopy as a novel platform for unveiling the heterogeneity of mesenchymal stem cells

Despite the significant potential of mesenchymal stem cells (MSC) therapy in clinical settings, challenges persist regarding the efficient detection of consistency and uniformity of MSC populations. Raman spectroscopy is a fast, convenient, and nondestructive technique to acquire molecular properties of biomolecules across laboratory and mass-production settings. Here we utilized Raman spectroscopy to evaluate the heterogeneity of primary MSC from varying donors, passages, and distinct culture conditions, and compared its effectiveness with conventional techniques such as flow cytometry. Although these MSC exhibited insignificant differences in morphology and surface markers in flow cytometry analysis, they could be distinctly clustered into different populations by Raman spectroscopy and the subsequent machine learning using linear discriminant analysis. Principal component analysis demonstrated limited efficiency in clustering Raman data from diverse sources, which could be enhanced through combination with support vector machine or deterministic finite automation. These findings highlight the sensitivity of Raman spectroscopy in detecting subtle differences. Moreover, the analysis of characteristic Raman peaks attributed to cellular biomolecules in MSC from passages 2 (P2) to P10 revealed a gradual decrease in the levels of nucleic acids, lipids, and proteins with increasing passages, and a significant increase in carotenoids from P8. These results suggest the potential use of Raman spectroscopy to assess cellular biochemical characteristics such as aging, with carotenoids emerging as a potential marker of cell aging. In conclusion, Raman spectroscopy demonstrates the ability to rapidly and non-invasively detect cellular heterogeneity and biochemical status, offering significant potential for quality control in stem cell therapy.

MiR-126 regulates the effect of mesenchymal stem cell vascular repair on carotid atherosclerosis through MAPK/ERK signaling pathway

BACKGROUND

Carotid atherosclerosis is a complex disease involving multiple cellular and molecular pathways. Mesenchymal stem cells (MSCs) show therapeutic potential, but their optimal targets and efficacy are still under study. MiR-126 enhances endothelial function and promotes angiogenesis by relieving vascular endothelial growth factor signaling suppression, suggesting its potential in vascular regeneration. However, its role in directing stem cell differentiation toward endothelial lineages remains unclear. We hypothesize that miR-126 may influence MSCs’ immunomodulatory and vascular reparative functions via the mitogen-activated protein kinases/extracellular signal-regulated kinase (MAPK/ERK) pathway, thereby improving carotid atherosclerosis. This study explores this mechanism to provide novel insights and support the development of miR-126-based therapeutic strategies.

AIM

To verify if miR-126 inhibits carotid atherosclerosis via the MAPK/ERK pathway.

METHODS

Rat bone marrow MSCs (product No. CP-R131, Wuhan, China) were verified by flow cytometry. The effects of miR-126 on MSCs’ proliferation, migration, apoptosis, and cytokine expression were explored using microRNA mimics and inhibitors. Fluorescence staining quantified CD31+ cells to evaluate endothelial differentiation. In vivo differentiation was assessed, and MSCs were transplanted into a rat carotid artery balloon dilatation model. Rats were randomly divided into five groups: Control, negative control mimics, miR-126 mimics, negative control inhibitor, and miR-126 inhibitor.

RESULTS

In vitro, MSCs treated with miR-126 mimics demonstrated enhanced proliferation, increased migration, and reduced apoptosis. These miR-126 mimics also significantly increased the secretion of vascular endothelial growth factor and basic fibroblast growth factor. Fluorescence and tissue staining indicated a higher proportion of CD31+ cells in the miR-126 mimics group. Additionally, the expression of endothelial-related genes (von Willebrand factor, endothelial nitric oxide synthase, and vascular endothelial-cadherin) was upregulated in this group. In vivo, miR-126-transfected MSCs effectively reduced neointimal thickness and promoted endothelial coverage in rats. MiR-126 stimulated MSC proliferation in a dose-dependent manner and reduced p38 and ERK1/2 phosphorylation. Conversely, miR-126 inhibition or blank controls resulted in opposing effects.

CONCLUSION

MiR-126 exerts significant modulatory effects on the immunoregulatory and vascular reparative functions of MSCs through the MAPK/ERK signaling pathway, promoting their differentiation into endothelial cells and thereby mitigating atherosclerosis.

Tissue Engineering and Regenerative Medicine: Perspectives and Challenges

From the pioneering days of cell therapy to the achievement of bioprinting organs, tissue engineering, and regenerative medicine have seen tremendous technological advancements, offering solutions for restoring damaged tissues and organs. However, only a few products and technologies have received United States Food and Drug Administration approval. This review highlights significant progress in cell therapy, extracellular vesicle-based therapy, and tissue engineering. Hematopoietic stem cell transplantation is a powerful tool for treating many diseases, especially hematological malignancies. Mesenchymal stem cells have been extensively studied. The discovery of induced pluripotent stem cells has revolutionized disease modeling and regenerative applications, paving the way for personalized medicine. Gene therapy represents an innovative approach to the treatment of genetic disorders. Additionally, extracellular vesicle-based therapies have emerged as rising stars, offering promising solutions in diagnostics, cell-free therapeutics, drug delivery, and targeted therapy. Advances in tissue engineering enable complex tissue constructs, further transforming the field. Despite these advancements, many technical, ethical, and regulatory challenges remain. This review addresses the current bottlenecks, emphasizing novel technologies and interdisciplinary research to overcome these hurdles. Standardizing practices and conducting clinical trials will balance innovation and regulation, improving patient outcomes and quality of life.

Advances in the Research of Mesenchymal Stromal Cells in the Treatment of Maxillofacial Neurological Disorders and the Promotion of Facial Nerve Regeneration

Maxillofacial neurological disorders include a range of disorders affecting the cranial nerves, which can be caused by a variety of reasons, including infection, trauma, tumor, and surgical complications, resulting in severe dysfunction, and the study of new approaches for the treatment of these disorders is crucial for the restoration of sensory and motor functions of the face. In recent years, due to the excellent tissue regenerative ability of mesenchymal stromal cells (MSCs), research on MSCs and MSC-derived exosomes has been progressively deepened, bringing many new perspectives to the therapeutic strategies for many diseases. Facial nerve regeneration is a complex process involving various pathophysiological mechanisms and therapeutic strategies to restore nerve function after injury. And the rapid development of stem cell tissue engineering has greatly facilitated the research process of facial nerve regeneration. In this paper, we review the characteristics of MSCs and neural stem cells (NSCs), the roles they play in the neural microenvironment and the mechanisms that promote nerve regeneration, summarize the research progress of MSCs in the treatment of maxillofacial neurological disorders, and highlight the promising directions for future development.

The influence of cell source on the senescence of human mesenchymal stem/stromal cells

While mesenchymal stem/stromal cells (MSCs) exhibit the ability to self-renew, they are not immortal; they eventually reach a point of irreversible growth cessation and functional deterioration following a limited series of population doublings, referred to as replicative senescence. When evaluated according to the criteria set by the International Society for Cell Therapy (ISCT), MSCs show significant differences in their senescence patterns and other characteristics related to their phenotype and function. These differences are attributed to the source of the MSCs and the conditions in which they are grown. MSCs derived from fetal or adult sources have variations in their genome stability, as well as in the expression and epigenetic profile of the cells, which in turn affects their secretome. Understanding the key factors of MSC senescence based on cell source can help to develop effective strategies for regulating senescence and improving the therapeutic potential.

Comparative analysis of transcriptomic profiles of mesenchymal stem cells at the onset of senescence and after exposure to acute exogenous oxidative stress

Cellular senescence can be triggered by a wide range of stress-inducing factors, including environmental and internal damaging events, such as oxidative stress. Moreover, stressed and senescent cells exhibit modifications in their transcriptional expression profile, but little is known regarding the common genes and pathways regulating these processes. Here, we analyzed the effects of long-term culture as well as exogenous acute oxidative stress on the transcriptional program of Wharton's jelly mesenchymal stem cells (WJ-MSCs). We demonstrate that, exposure to H2O2 compromised genomic stability and mitochondrial function in early passage WJ-MSCs, potentially initiating senescence to prevent cellular transformation. On the other hand, prolonged in vitro expansion of WJ-MSCs activated processes linked to integrins and extracellular matrix organization, possibly indicating the unfavorable consequences that senescence has on tissue integrity. Additionally, cells entering senescence and oxidative stressed young WJ-MSCs over-activated transcription factors related to permanent proliferative arrest and suppressed anti-senescence factors. Common differentially expressed genes in the late passage and H2O2-treated WJ-MSCs were implicated in DNA damage response and cell cycle arrest, which are known to trigger a senescent phenotype. Notably, the TP53INP1 gene emerged as a significantly upregulated gene in both late passage and H2O2-treated young WJ-MSCs, marking it as a potent senescence indicator. Silencing TP53INP1 mitigated the senescent phenotype, a role that appeared to be facilitated by autophagy regulation. Taken together, our results shed light on how transcriptomic changes govern MSCs' senescence program and identify key molecular drivers that could prove crucial for WJ-MSCs-based clinical applications.

Mesangiogenic progenitor cells: a mesengenic and vasculogenic branch of hemopoiesis? A story of neglected plasticity

Mesangiogenic progenitor cells (MPCs) are mesengenic and vasculogenic cells isolated from human bone marrow mononuclear cell cultures. Although MPCs were first described over two decades ago and have demonstrated promising differentiation capabilities, these cells did not attract sufficient attention from experts in the field of tissue regeneration. Several reports from the first decade of the 2000s showed MPC-like cells co-isolated in primary mesenchymal stromal cell (MSC) cultures, applying human serum. However, in most cases, these rounded and firmly attached cells were described as "contaminating" cells of hemopoietic origin. Indeed, MPC morphology, phenotype, and functional features evoke but do not completely overlap with those of cultured peripheral macrophages, and their hemopoietic origin should not be excluded. The plasticity of cells from the monocyte lineage is surprising but not completely unprecedented. Underestimated data demonstrated that circulating monocyte/macrophages could acquire broader plasticity under specific and different culture conditions, and this plasticity could be a consequence of in vitro de-differentiation. The evidence discussed here suggests that MPCs could represent the cell identity toward which the de-differentiation process reprograms the circulating mature phagocytic compartment.

Emerging role of mesenchymal cells in cardiac and cerebrovascular diseases: Physiology, pathology, and therapeutic implications

In recent years, the therapeutic utility of mesenchymal stem cells (MSCs) has received substantial attention from investigators, owing to their pleiotropic properties. The emerging insights from the developments in tissue engineering provide perspectives for the repair of damaged tissue and the replacement of failing organs. Perivascular cells including MSC-like pericytes, vascular smooth muscles, and other cells located around blood vessels, have been acknowledged to contribute to in situ angiogenesis and repair process. MSCs offer a wide array of therapeutic applications in different pathological states. However, in the current article, we have highlighted the recent updates on MSCs and their key applications in cardiac and cerebrovascular diseases, evident in different preclinical and clinical studies. We believe the present article would assist the investigators in understanding the recent advances of MSCs and exploring their therapeutic potential in varied ailments, especially cardiac and cerebrovascular diseases.

Cell Homing Strategies in Regenerative Endodontic Therapy

Cell homing, a process that leverages the body's natural ability to recruit cells and repair damaged tissues, presents a promising alternative to cell transplantation methods. Central to this approach is the recruitment of endogenous stem/progenitor cells-such as those from the apical papilla, bone marrow, and periapical tissues-facilitated by chemotactic biological cues. Moreover, biomaterial scaffolds embedded with signaling molecules create supportive environments, promoting cell migration, adhesion, and differentiation for the regeneration of the pulp-dentin complex. By analyzing in vivo animal studies using cell homing strategies, this review explores how biomolecules and scaffold materials enhance the recruitment of endogenous stem cells to the site of damaged dental pulp tissue, thereby promoting repair and regeneration. It also examines the key principles, recent advancements, and current limitations linked to cell homing-based regenerative endodontic therapy, highlighting the interplay of biomaterials, signaling molecules, and their broader clinical implications.

Analyte heterogeneity analysis as a possible potency parameter for MSC

Mesenchymal stem/stromal cells (MSC) have been transplanted for therapeutic purposes with inconsistent results. MSC preparations are heterogeneous, and this person-to-person heterogeneity may account for the variable clinical outcomes. Additionally, the mechanisms of therapeutic action for MSC are unclear which confounds attempts to understand and identify factors that may account for variable clinical results. Here, we report our analysis of MSC preparations for the expression levels of molecules that have been hypothesized to mediate MSC function. Although most of the analytes assessed demonstrated little divergent expression, several molecules were found with enhanced heterogeneity both within individual MSC preparations and among MSC preparations from the sample of multiple sclerosis patients. The variable expression of these molecules may relate to the therapeutic heterogeneity of MSC. Additionally, we found a novel set of molecules that were highly intercorrelated in MSC. The tight association of this group of molecules may represent an invariant molecular organization that is integral to MSC activity. The precise analysis of molecular expression levels in MSC has the potential to answer concerns about variable therapeutic effects of MSC transplantation as well as to understand the mechanism of clinical effects.

Mesenchymal Stromal Cells for Aging Cartilage Regeneration: A Review

Cartilage degeneration is a key feature of aging and osteoarthritis, characterized by the progressive deterioration of joint function, pain, and limited mobility. Current treatments focus on symptom relief, not cartilage regeneration. Mesenchymal stromal cells (MSCs) offer a promising therapeutic option due to their capability to differentiate into chondrocytes, modulate inflammation, and promote tissue regeneration. This review explores the potential of MSCs for cartilage regeneration, examining their biological properties, action mechanisms, and applications in preclinical and clinical settings. MSCs derived from bone marrow, adipose tissue, and other sources can self-renew and differentiate into multiple cell types. In aging cartilage, they aid in tissue regeneration by secreting growth factors and cytokines that enhance repair and modulate immune responses. Recent preclinical studies show that MSCs can restore cartilage integrity, reduce inflammation, and improve joint function, although clinical translation remains challenging due to limitations such as cell viability, scalability, and regulatory concerns. Advancements in MSC delivery, including scaffold-based approaches and engineered exosomes, may improve therapeutic effectiveness. Potential risks, such as tumorigenicity and immune rejection, are also discussed, emphasizing the need for optimized treatment protocols and large-scale clinical trials to develop effective, minimally invasive therapies for cartilage regeneration.

Clinical outcome is unlinked to injection of adipose-derived regenerative cells in the axilla of breast cancer-related lymphedema patients

BACKGROUND

Injection of autologous adipose-derived regenerative cells (ADRCs) combined with lipotransfer has been suggested to alleviate symptoms in diseases including breast cancer-related lymphedema (BCRL). We recently performed a randomized controlled trial injecting lipoaspirate with ADRCs into the axilla of BCRL patients, and here we aimed in the intervention group to define in an unbiased fashion whether ADRC injection was linked to the clinical outcome.

METHODS

39 BCRL patients received lipotransfer assisted with autologous ADRCs (4.20 × 107 ± 1.75 × 107 cells) whereas 41 BCRL patients were included for placebo treatment. At 12 month follow-up, we assessed quality of life, lymphangiography, and bioimpedance enclosing 59 outcome parameters. Multifactorial analysis of clinical outcomes was used to define responders and non-responders to the intervention, and collected ADRCs from these patient groups were analyzed by single cell RNA sequencing (scRNAseq).

RESULTS

Unbiased multifactorial analysis ranked and defined the clinical outcomes (Sf36 physical change, L-Dex Lymph Change, ICG mdanderson change) with the highest effect on BCRL patients. The 10 patients with the highest- and lowest effect (five responders and five non-responders) were included in the study. No difference between non-responders and responders were observed for injected ADRC number/size/viability (p > 0.05). In scRNAseq, we did not find any major difference (p > 0.05) between groups in ADRC composition regarding adipose derived stem cells, endothelial-, smooth muscle-, T-, B-, mast cells as well as macrophages, which was verified by flow cytometry. Differential subcluster gene expression between groups were for 92.5% of genes, including those encoding secretory proteins, below the threshold of 1.5, and thus neglible. Together this suggested that the ADRC phenotype was indistinguishable between BCRL responders and non-responders to the intervention.

CONCLUSION

Our data suggest that the ADRC injection and ADRC phenotype or heterogeneity have no effect on the clinical outcomes on BCRL, and ADRC assisted lipotranfer for BCRL should therefore not be considered currently.

Advancements in Research on Mesenchymal Stem-Cell-Derived Exosomal miRNAs: A Pivotal Insight into Aging and Age-Related Diseases

Mesenchymal stem cells (MSCs) are capable of differentiating into various cell types and play a crucial role in repairing aging tissues and diseased organs. Aging manifests as a gradual loss of cellular, tissue, and organ function, leading to the progression of pathologies. Exosomes (Exos) are extracellular vesicles secreted by cells, which maintain cellular homeostasis, clear cellular debris, and facilitate communication between cells and organs. This review provides a comprehensive summary of the mechanisms for the synthesis and sorting of MSC-Exo miRNAs and summarizes the current research status of MSCs-Exos in mitigating aging and age-related diseases. It delves into the underlying molecular mechanisms, which encompass antioxidative stress, anti-inflammatory response, and the promotion of angiogenesis. Additionally, this review also discusses potential challenges in and future strategies for advancing MSC-Exo miRNA-based therapies in the treatment of aging and age-related diseases.

Comparison of Autologous and Allogeneic Adipose-Derived Stem Cells in Kidney Transplantation: Immunological Considerations and Therapeutic Efficacy

Regenerative medicine shows significant potential in treating kidney diseases through the application of various types of stem and progenitor cells, including mesenchymal stem cells (MSCs), renal stem/progenitor cells, embryonic stem cells (ESCs), and induced pluripotent stem cells (iPSCs). Stem cells possess the unique ability to repair injured organs and improve impaired functions, making them a key element in the research of therapies for kidney tissue repair and organ regeneration. In kidney transplantation, reperfusion injury can cause tissue destruction, leading to an initially low glomerular filtration rate and long-term impact on function by creating irreversible interstitial fibrosis. MSCs have proven useful in repairing early tissue injury in animal models of kidney, lung, heart, and intestine transplantation. The use of stem cell therapies in solid organ transplantation raises the question of whether autologous or allogeneic cells should be preferred. Adipose-derived stem cells (ASCs), characterized by the lack of HLA Class II molecules and low expression of HLA Class I and co-stimulatory signals, are considered immune-privileged. However, the actual risk of graft rejection associated with allogeneic ASCs remains unclear. It has been demonstrated that donor-derived ASCs can promote the development of Treg cells in vitro, and some degree of tolerance induction has been observed in vivo. Nevertheless, a study comparing the efficacy of autologous and allogeneic ASCs in a rat model with a total MHC mismatch for kidney transplantation showed that donor-derived administration of ASCs did not improve the grafts' survival and was associated with increased mortality through an immunologically mediated mechanism. Given the lack of data, autologous ASCs appear to be a safer option in this research context. The aim of this review was to examine the differences between autologous and allogeneic ASCs in the context of their application in kidney transplantation therapies, considering potential immune reactions and therapeutic efficacy. Some have argued that ASCs harvested from end-stage renal disease (ESRD) patients may have lower regenerative potential due to the toxic effects of uremia, potentially limiting their use in transplantation settings. However, evidence suggests that the beneficial properties of ASCs are not affected by uremia or dialysis. Indeed, some investigators have demonstrated that ASCs harvested from chronic kidney disease (CKD) patients exhibit normal characteristics and function, maintaining consistent proliferative capacity and genetic stability over time, even after prolonged exposure to uremic serum Furthermore, no differences were observed in the response of ASCs to immune activation or their inhibitory effect on the proliferation of alloantigen-activated peripheral blood mononuclear cells between patients with normal or impaired renal function. This review presents the current achievements in stem cell research aimed at treating kidney diseases, highlighting significant progress and ongoing efforts in the development of stem cell-based therapies. Despite the encouraging results, further research is needed to overcome the current limitations and fully realize the potential of these innovative treatments. Advances in this field are crucial for developing effective therapies that can address the complex challenges associated with kidney damage and failure.

Role of Mesenchymal Stem/Stromal Cells in Head and Neck Cancer-Regulatory Mechanisms of Tumorigenic and Immune Activity, Chemotherapy Resistance, and Therapeutic Benefits of Stromal Cell-Based Pharmacological Strategies

Head and neck cancer (HNC) entails a heterogenous neoplastic disease that arises from the mucosal epithelium of the upper respiratory system and the gastrointestinal tract. It is characterized by high morbidity and mortality, being the eighth most common cancer worldwide. It is believed that the mesenchymal/stem stromal cells (MSCs) present in the tumour milieu play a key role in the modulation of tumour initiation, development and patient outcomes; they also influence the resistance to cisplatin-based chemotherapy, the gold standard for advanced HNC. MSCs are multipotent, heterogeneous and mobile cells. Although no MSC-specific markers exist, they can be recognized based on several others, such as CD73, CD90 and CD105, while lacking the presence of CD45, CD34, CD14 or CD11b, CD79α, or CD19 and HLA-DR antigens; they share phenotypic similarity with stromal cells and their capacity to differentiate into other cell types. In the tumour niche, MSC populations are characterized by cell quiescence, self-renewal capacity, low reactive oxygen species production and the acquisition of epithelial-to-mesenchymal transition properties. They may play a key role in the process of acquiring drug resistance and thus in treatment failure. The present narrative review examines the links between MSCs and HNC, as well as the different mechanisms involved in the development of resistance to current chemo-radiotherapies in HNC. It also examines the possibilities of pharmacological targeting of stemness-related chemoresistance in HNSCC. It describes promising new strategies to optimize chemoradiotherapy, with the potential to personalize patient treatment approaches, and highlights future therapeutic perspectives in HNC.