STEM CELLS最新文献

Hematopoietic aging is characterized by diminished stem cell regenerative capacity and an increased risk of hematologic dysfunction. We previously identified that the prostaglandin-degrading enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH) regulates hematopoietic stem cell (HSC) activity. Here, we expand on this work and demonstrate that in aged mice: (1) 15-PGDH expression and activity remain conserved in the bone marrow (BM) and spleen, suggesting that it remains a viable therapeutic target in aging; (2) prolonged PGDH inhibition (PGDHi) significantly increases the frequency and number of phenotypic hematopoietic stem and progenitor cells across multiple compartments, with transcriptional changes indicative of enhanced function; (3) PGDHi-treated BM enhances short-term hematopoietic recovery following transplantation, leading to improved peripheral blood output and accelerated multilineage reconstitution; and (4) PGDHi confers a competitive advantage in primary hematopoietic transplantation while mitigating age-associated myeloid bias in secondary transplants. Notably, these effects occur without perturbing steady-state blood production, suggesting that PGDHi enhances hematopoiesis under regenerative conditions while maintaining homeostasis. Our work identifies PGDHi as a translatable intervention to rejuvenate aged HSCs and mitigate hematopoietic decline.

Mesenchymal stromal cells (MSCs), owing to their regenerative and immunomodulatory properties, have emerged as a potential therapeutic option for disorders affecting the cornea and ocular surface. Early-phase clinical studies have begun to demonstrate the safety and, to some extent, efficacy of MSC-based therapies in conditions such as dry eye disease, persistent corneal epithelial defects, ocular chemical injuries, corneal scarring, keratoconus, and limbal stem cell deficiency. However, evidence from some studies suggests that MSC-related improvements may be short-lived. Currently, the appropriate clinical indications, delivery methods, and long-term outcomes remain unclear, necessitating further laboratory and clinical investigations. In this review, we summarize published and ongoing clinical studies on the therapeutic applications of MSCs for ocular surface diseases, including our own group's experience. We critically evaluate the strengths and limitations of existing studies and highlight gaps and opportunities in this evolving field.

The study by Ye et al., published in Stem Cells, represents a significant advancement in the field of cellular reprogramming and pluripotency. The authors meticulously investigate the essential roles of the miR-290 and miR-302 microRNA clusters in the reprogramming of fibroblasts to induced pluripotent stem cells (iPSCs). This work is distinguished by its comprehensive experimental design and rigorous methodology, providing novel insights into the molecular mechanisms underlying iPSC formation.

Existing protocols for in vitro hyaline cartilage production utilizing human induced pluripotent stem cells (hiPSCs) have several challenges including a complex culturing process that uses undefined culture media, phenotypic instability, and batch-to-batch variability of the cell product. Here, our primary objective is to describe a simple, xeno- and feeder-free protocol for the generation of hyaline cartilage utilizing multi-tissue organoids (MTOs). We investigated gene regulatory networks during hiPSC-MTO differentiation using RNA sequencing and bioinformatics analyses, as well as histological and immunohistochemical methods. Interplays between bone morphogenetic protein (BMP) and neural fibroblast growth factor (FGF) pathways associated with the phenotypic transition of MTOs are described. Comparisons across transcriptomes revealed that the expression of chondrocyte-specific genes in MTOs correlates strongly with fetal lower limb chondrocytes. Single-cell RNA sequencing findings confirmed that the majority of cells belonged to the chondrogenic lineage and that they were similar across MTO batches, suggesting uniformity of the culture process. Collectively, these findings demonstrate the consistent emergence of hyaline cartilage in MTOs and the molecular pathways that govern this process, thereby establishing an accessible source of functional chondrocytes for future therapeutic evaluations.

Mesenchymal stem cells (MSCs) have been widely studied for treating immune-mediated diseases due to their immunomodulatory abilities. Recent studies have shown that priming MSCs with inflammatory cytokines can enhance these functions, yet the optimal priming conditions for canine MSCs remain poorly defined. In this study, we investigated the effects of priming canine adipose tissue-derived MSCs (cAMSCs) with inflammatory cytokines IFN-γ, TNF-α, and IL-17 at various concentrations (10, 20, and 50 ng/mL) to evaluate their immunomodulatory and migratory capacities. Of the 3 cytokines evaluated, only IFN-γ priming significantly enhanced the expression of immunosuppressive genes IDO and PD-L1, and robustly suppressed T-cell proliferation across all concentrations compared to naïve cAMSCs in both direct co-culture and indirect (conditioned medium) assays. TNF-α priming significantly increased HGF expression and promoted cell cycle progression, while IL-17 priming upregulated COX2 and TGF-β expression; however, both exhibited limited immunomodulatory effects compared to IFN-γ. In addition, IFN-γ induced strong expression of adhesion and migration-related genes, including E-CADHERIN, ICAM1, and VCAM1, and promoted cAMSCs migration in a wound healing assay. Despite increasing MHC II, IFN-γ did not induce CD80, preserving the low immunogenic profile of cAMSCs. These findings support IFN-γ priming as the most effective strategy to enhance the immunomodulatory and migratory functions of cAMSCs, offering substantial potential for MSC-based therapies in veterinary medicine.

The maintenance of corneal epithelial homeostasis relies on limbal stem cells (LSCs) located at the limbus. Although short-term cultured LSC transplantation effectively treats LSC deficiency, prolonged culture leads to stemness loss and abortive colony formation, and the mechanisms remain elusive. In this study, we employed single-cell transcriptomics to investigate LSC population dynamics and changes in gene expression during extended serial culture. Transcriptomic data from 22 708 cells revealed 19 clusters, identifying 3 distinct limbal progenitor populations (Progenitors 1-3) with unique transcriptional profiles and cell division kinetics. All progenitor subgroups expressed stemness-related genes such as ANLN, AURKB, and HMGB2 and were detected at all stages of the cell cycle. Notably, Progenitor3 exhibited the highest levels of genes associated with stemness and the G2/M checkpoint, including ANLN, PLK1, AURKA, HMGB2, and TOP2A, and had the largest proportion of cells in G2/M. Progenitor2 was marked by histone H1 expression, while Progenitor1 displayed distinctive cell cycle kinetics. Despite stable proportions of the three progenitor populations throughout prolonged passaging, mitochondrial gene downregulation, and ribosomal gene upregulation were observed. Treatment with the small molecule RepSox partially preserved LSC maintenance in long-term culture by inhibiting the epithelial-mesenchymal transition program and modulating energy and metabolic pathways. These findings provide insights for optimizing in vitro LSC expansion for cell-based therapies.

The development of committed erythroid progenitors and their continued maturation into erythrocytes requires the cytokine erythropoietin (Epo). Here, we describe the immunophenotypic identification of a CD34- colony-forming unit-erythroid (CFU-E) progenitor subtype, termed late CFU-E (lateC), that arises in an Epo-dependent manner during human early erythropoiesis (EE). LateC cells lack CD235a (glycophorin A) but have high levels of CD71 and CD105, characterized as Lin-CD123-CD235a-CD49d+CD117+CD34-CD71hiCD105hi. Analysis of ex vivo cultures of bone marrow (BM) CD34+ cells showed that acquisition of the CD71hiCD105hi phenotype in lateC occurs through the formation of four other EE subtypes. Of these, two are CD34+ burst-forming unit-erythroid (BFU-E) cells, distinguishable as CD71loCD105lo early BFU-E (earlyB) and CD71hiCD105lo late BFU-E (lateB), and two are CD34- CFU-E, also distinguishable as CD71loCD105lo early CFU-E (earlyC) and CD71hiCD105lo mid CFU-E (midC). The EE transitions are accompanied by a rise in CD36 expression, such that all lateC cells are immunophenotypically CD36+. Patterns of CD34, CD36, and CD71 indicate two differentiation routes-in one earlyB lose CD34 to form earlyC, and in another, earlyB gain CD36 and CD71hi expression prior to losing CD34 to form midC, bypassing the earlyC stage. Regardless of the route, the transition from midC to lateC requires Epo. All five EE subtypes could be prospectively detected in human BM cells and, upon isolation and reculture, exhibited the potential to continue differentiating along the erythroid trajectory. Finally, we find that all five EE populations can also be detected in cultures of cord blood-derived CD34+ cells at levels similar to those observed in BM CD34+ cell cultures.

Introduction: Systemic lupus erythematosus (SLE) is driven by abnormal type-I and -II interferon activation, affecting a variety of immunocompetent cells. Mesenchymal stromal cells (MSCs) can modulate inflammation but often lack consistent potency. We developed HXB-319, an MSC-based therapy targeting inflammatory pathways in SLE. Previously, HXB-319 was shown to reduce alveolar hemorrhage in an SLE model. Here, we report its effects in a model of SLE that progresses to end stage kidney disease.

Materials and methods: SLE-like disease was induced via intraperitoneal (IP) pristane injection in female BALB/cJ mice, followed by treatment with naïve MSCs or HXB-319. Over 9 months, survival and proteinuria were monitored. Upon euthanasia, kidneys were analyzed for histopathology and gene expression, splenocytes for immune subsets by flow cytometry, and serum for autoantibodies, growth factors, and cytokines.

Results: HXB-319 significantly altered plasmacytoid dendritic cells, CD4+PD-L1+ cells, and both CD4+ and CD8+ RORγt+ (Th17 cells) subsets. HXB-310 lowered IFN-γ (P < 0.001), IL-17A (P = 0.01), BAFF (P < 0.05), and anti-dsDNA (P < 0.05), compared to untreated mice. HXB-319, but not naïve MSCs, significantly improved survival, halted progression of kidney disease, and stabilized proteinuria (all P < 0.05).

Conclusion: HXB-319 demonstrates potential for mitigating SLE-associated glomerulonephritis, improving survival, and reducing proteinuria and glomerulosclerosis.

The hypothalamus-pituitary-adrenal (HPA) axis is crucial for energy metabolism, cardiovascular function, and stress response. Importantly, neuronal signaling circuits in the hypothalamus, along with hormones released from the pituitary and adrenal gland, must adapt to physiological demands or pathological conditions. Stem and progenitor cells are pivotal in this regulation, either by giving rise to distinct cell types or by interacting with progenitor or hormone-producing cells. While lineage-tracing studies in rodent models have explored the role of stem cells in the HPA axis, our understanding of the mechanisms underlying this dynamic tissue plasticity remains limited, especially in humans. Moreover, single-cell RNA sequencing has revealed significant heterogeneity among stem cell populations in the HPA-axis, raising questions about the functional relevance of individual subclusters during development and adulthood. In this concise review, we summarize current knowledge on stem cells in the HPA axis, focusing on their origins, localization of different stem cell populations, and sex-specific activity in maintaining tissue integrity. We further address their role under pathophysiological conditions, including metabolic disease, cancer, and stress. Lastly, we discuss emerging strategies for replacing lost or damaged stem or progenitor cells during aging, highlighting recent achievements in the in vitro differentiation of hypothalamic, pituitary, and adrenal stem cells.

Residual beta cell function has been documented in "medalist" patients who have lived with Type 1 diabetes (T1D) for >50 years. In addition, endocrine cell neogenesis first occurs in the developing human embryo from progenitor cells derived from pancreatic ductal epithelial structure. Thus, beta cell conversion from a dormant epithelial precursor remains a promising approach to regenerate islets during T1D. We have previously shown that intra-pancreatic (iPan) injection of Wnt pathway-stimulated conditioned media (Wnt+ CdM) generated from human bone marrow-derived multipotent stromal cells (MSC) contained islet regenerative factors that reduced hyperglycemia and recovered beta cell mass in streptozotocin-treated mice. However, the endogenous source of regenerated beta cells remains unknown. Herein, we employed cytokeratin 19 (CK19)-CreERT Rosa26-mTomato lineage-tracing mice to assess the endocrine conversion of CK19+ cells during MSC CdM-induced islet regeneration. Mice iPan-injected with Wnt+ CdM demonstrated reduced blood glucose levels and improved glucose tolerance compared to mice injected with unconditioned basal media. CdM-injected mice also showed increased islet number and beta cell mass, as well as CK19+ cells within regenerating islets. The frequency of insulin + cells that co-expressed tdTomato within dissociated pancreas samples observed via flow cytometry was 5-fold higher in Wnt+ CdM-injected mice (~5%) compared to basal media-injected controls (~1%). Collectively, in vivo lineage tracing revealed conversion of CK19+ cells to functional beta cells partially contributed to islet regeneration induced by Wnt-activated MSC CdM. Future studies are required to delineate alternate cell types and mechanisms participating in islet regeneration induced by direct delivery of MSC-CdM.