STEM CELLS最新文献

Background: Peripheral nerve injuries (PNIs) present a persistent clinical challenge because of the intrinsically limited regenerative capacity of peripheral nerves. While dental pulp stem cells (DPSCs) exhibit significant neuroregenerative potential, their therapeutic efficacy is constrained by hostile microenvironments and inherent functional heterogeneity. Genetic modification may offer a promising strategy to enhance their therapeutic capabilities.

Methods: DPSCs were induced toward neural lineage differentiation, and key gene candidates were identified through qRT-PCR. Lentiviral-mediated gene interference was performed to modulate target gene expression, followed by comprehensive analysis of differentiation outcomes using qRT-PCR, Western blotting, and immunofluorescence assays. RNA sequencing was employed to uncover associated signaling pathways, which were subsequently validated through pharmacological inhibition with specific inhibitors. The therapeutic efficacy of genetically engineered DPSCs was evaluated in a rat model of sciatic nerve crush injury, with neural regeneration quantitatively assessed via neuroelectrophysiological measurements and histological analyses.

Results: LARP7 positively regulated the Schwann cell-like differentiation of DPSCs, as well as their trophic and anti-inflammatory effects, thus enhancing its therapeutic effects on nerve repair and promoting functional recovery. Mechanistically, we found that LARP7 remodeled cytokine-cytokine receptor interactions, enhancing trophic support while attenuating proinflammatory responses, and activated the PI3K-Akt-mTOR signaling pathway, with ERBB4 serving as a critical downstream effector, promoting DPSC differentiation into Schwann cell-like phenotypes.

Conclusions: Collectively, LARP7-mediated changes in DPSCs establish a new therapeutic paradigm that addresses the limitations of current stem cell-based interventions and enables the development of standardized biotherapeutics for peripheral nerve repair.

Muscle satellite cells are adult muscle stem cells indispensable for growth and regeneration of postnatal skeletal muscle. Notch plays a central role in maintenance of muscle satellite cells, but how Notch maintains the muscle stem cell pool is not fully understood. Previously, we reported that a prostaglandin E2 receptor, EP2, is upregulated by Notch signal and suppresses differentiation of human muscle progenitors. Here we examined the roles of EP2 in muscle satellite cells using a mouse Cre-LoxP conditional gene knockout system. Genetic inactivation of the EP2 gene (PTGER2) activated muscle satellite cells, caused their loss, and impaired muscle regeneration. These results indicate that EP2 is indispensable for maintenance of satellite cells. Ex vivo analysis using isolated myofibers showed that prostaglandin E2 (PGE2) delayed the activation of satellite cells via EP2. An extracellular signal-regulated kinase (ERK) 1/2 inhibitor blocked the activation of satellite cells on myofibers, and PGE2 attenuated the phosphorylation of ERK1/2 in muscle satellite cells. These results suggest that EP2 keeps the quiescence of satellite cells and maintains the satellite cell pool in part by inhibiting the ERK1/2 signaling pathway.

The sense of smell is maintained by regenerating olfactory sensory neurons (OSNs) from basal stem cells in the olfactory epithelium (OE). Acute inflammation destroys OSNs, causing hyposmia and anosmia, but activates basal cells. Manipulation of signaling pathways to promote basal cell proliferation and neuroregeneration would reveal novel therapeutic targets for smell deficits. We found that ciliary neurotrophic factor (CNTF) from horizontal basal cells (HBCs, quiescent stem cells) promotes neuroregeneration and functional recovery following methimazole-induced acute injury. Moreover, inhibition of focal adhesion kinase (FAK) upregulates CNTF in naïve OE. Here, we show that the small molecule FAK inhibitor increased CNTF expression in cultured primary HBCs isolated from methimazole-treated mice. Although methimazole-induced CNTF did not seem to be through FAK signaling, inducible cre-lox knockout of FAK in HBCs in mice further increased CNTF expression, as well as Mash1, a marker for globose basal cells (GBCs, neuronal progenitors), and GBC proliferation. Moreover, intranasal aspiration, but not systemic treatment, of a water-soluble pharmacological FAK inhibitor (FAK14) 3 days following methimazole, dose-dependently increased CNTF and Mash1 expression, and GBC proliferation. Intranasal FAK14 also enhanced methimazole-induced regeneration of new OSNs in CNTF+/+, but not in CNTF-/-, mice, demonstrating that FAK14 boosts neuroregeneration through additional CNTF following acute inflammation. Finally, intranasal FAK14 instillation following methimazole improved the functional recovery of smell. This study identifies the therapeutic potential of intranasal application of FAK inhibitors to enhance olfactory neuroregeneration and function following injury.

Postnatal skeletal growth in childhood and adolescence depends on cartilage organs called (epiphyseal) growth plates. Studies in the last decade have identified populations of skeletal stem cells within mouse growth plates' resting zones. While cellular quiescence is vital for the maintenance of many tissue-resident stem cell populations, the resting zone chondrocytes have been labelled "quiescent" for decades. However, the features of cellular quiescence that have been reported in the postnatal resting zone, how they were defined or experimentally assessed, and knowledge gaps relative to other quiescent cell types, remain to be well described. To address this, we conducted a systematic review, using the PRISMA guidelines, to identify studies of resting zone chondrocytes including the prefix "quiescen*". Definitions, keywords, chronological data and experimental findings were extracted. Our analysis demonstrated that, compared to those in other well-studied tissues, features of cellular quiescence in RZ chondrocytes remain poorly reported and underexplored, with limited molecular and functional characterization. Furthermore, while most identified studies reported changes in cell division parameters, integration between cues controlling resting zone cell quiescence is incomplete and heterogeneity among the various sub-populations of RZ cells/potential quiescent states is yet to be fully determined. This review identifies consensuses and knowledge gaps between studies and between quiescent RZ cells and those in other tissues and can act to enhance consistency and comparability in future studies of "quiescence" in the RZ chondrocytes.

Glaucoma represents a group of diseases where the unifying theme is the progressive degeneration of retinal ganglion cells (RGCs), causing irreversible vision loss. Mutations in the myocilin (MYOC) gene represent one of the most common genetic factors associated with primary open-angle glaucoma (POAG). However, the mechanism underlying MYOC mutation-associated POAG is poorly understood. Here, using human disease modeling of MYOC mutation (A445V)-dependent POAG, which is usually without ocular hypertension, we have tested a hypothesis that human RGCs (hRGCs) are the target of the mutant protein, making them vulnerable to degenerative changes. Examination of hRGCs generated from MYOCA445V POAG patient-specific induced pluripotent stem cells (iPSCs) revealed that their differentiation is adversely affected, compared to those generated from isogenic control iPSCs. Retinal ganglion cells regulatory and axon growth and guidance gene expression is decreased in patient-specific hRGCs vs isogenic controls. Consequently, the former display immature neurites and their ability to form synapses with the target cells and regenerate are compromised. Furthermore, they display immature networking physiology compared to isogenic controls. The pathological burden of the mutant protein is reflected in their preferential retention in the endoplasmic reticulum (ER) of patient-specific hRGCs, activating the unfolded protein response (UPR) toward mutation-associated developmental phenotype. Furthermore, we demonstrate that REDD1, a stress-induced factor, is a mechanistic link between the MYOCA445V-activated UPR axis and inhibited mTOR signaling, a critical regulator of RGC development and function. Ours is the first demonstration of MYOC mutation-dependent hRGC phenotype and posits a mechanism for hRGC susceptibility toward degeneration independent of ocular hypertension.

Stem cells use oxidized nicotinamide adenine dinucleotide (NAD+) in distinct subcellular compartments to support self-renewal and to regulate chromatin. There is limited information, however, about the biosynthetic pathways that replenish intracellular NAD+, which is continuously turned over in undifferentiated mouse embryonic stem cells. Establishing specific metabolic inputs for maintaining self-renewal can help direct reprogramming efforts. We used single fluorescent protein biosensors for in situ NAD+ measurements in J1 mouse embryonic stem cells. Sensors and controls were localized to the nucleus, cytoplasm, and mitochondrial compartments. Using a specific inhibitor for nicotinamide salvage, we found that loss of this pathway depleted NAD+ concentrations in all three subcellular compartments in undifferentiated culture conditions. We determined that loss of nicotinamide salvage reduced colony size, extended cell cycle, and resulted in diminished expression of self-renewal markers. Supplementation with precursors in the nicotinamide salvage pathway bypassed the pharmacological block, replenished cytosolic NAD+ levels, and reversed the effects on colony size. Notably, supplementation with deaminated precursors did not replenish intracellular NAD+ levels, suggesting minimal contribution from this pathway at this stage. In support, expression data from multiple mouse and human lines showed that nicotinamide salvage pathway enzyme NAMPT was predominantly expressed at the embryonic stem cell stage compared to the enzymes in other NAD+ biosynthesis pathways. Collectively, the data showed that undifferentiated embryonic stem cells heavily rely on nicotinamide salvage, indicating that this dependency is conserved.

During the heart development, epicardial-to-mesenchymal transition (EMT) drives the production of progenitor cell populations that contribute to heart formation; however, the molecular control of EMT and its paracrine effects on cardiomyocytes remain poorly elucidated. Here, we defined a novel PKR1-miR-124-SNAI2 signaling axis that orchestrates EMT and coordinates myocardial maturation. Conditional deletion of the prokineticin receptor (PKR1) in mice Tcf21+ epicardial cells caused embryonic lethality and congenital heart disease-like anomalies, including ventricular rupture, arrhythmia, myocardial fibrosis, and impaired contractility. Transcriptomic profiling revealed marked upregulation of miR-124, concurrent with deregulation of EMT genes and signatures of immature cardiomyocytes. Mechanistically, miR-124 directly targets the 3' untranslated region of SNAI2, suppressing this key EMT regulator, resulting in failed EMT, apoptosis, and fibrosis in the epicardium. Functional rescue through miR-124 inhibition or PKR1 reintroduction restores SNAI2 expression, revives EMT, enhances cell survival, and promotes proper cardiomyocyte maturation. Paracrine effects were substantiated by conditioned media and ex vivo assays, demonstrating that epicardial-derived miR-124 suppressed cardiomyocyte contractility and cardiac maturity gene expression-thereby functionally linking epicardial disruption to myocardial immaturity. These findings establish miR-124 as a critical mediator of epicardial-myocardial communication with PKR1 as its upstream regulator. By integrating epicardial plasticity, myocardial maturation, and ECM homeostasis, our work reveals that targeting the PKR1-miR-124-SNAI2 pathway offers a novel mechanistic framework and potential therapeutic target for preventing or treating congenital heart disease.

Hematopoietic stem cell (HSC) transplantation is a potentially curative option for patients with hematologic malignancies, but donor shortages impact graft availability. Umbilical cord blood (UCB) is a viable alternative source of HSC; however, the limited numbers present in a single unit have spurred efforts to expand HSC ex vivo. We previously demonstrated that the addition of valproic acid (VPA), an anti-convulsive drug, to CB cell cultures promotes maintenance of functional HSC, but not expansion. However, it has been proposed that VPA primarily induces mitochondrial reprogramming of mature CD34+CD90- cells to more primitive CD34+CD90+ cells, rather than the replication of CD34+CD90+ cells in culture. To determine which fraction of the CD34+CD90+ cells present after culture in VPA were derived from CD34+CD90- vs. CD34+CD90+ cells, we examined the functionality of CD34+CD90+ cells derived from each flow cytometry-sorted population. During culture in VPA there was a significant increase in CD34+CD90+ cell number; the majority arising from pre-existing CD34+CD90+ cells, with minimal contribution from CD34+CD90- cells. Colony-forming unit (CFU) assays revealed reduced plating efficiency and xeno-transplantation studies demonstrated diminished in vivo hematopoietic reconstitution potential of CD34+CD90+ cells derived from relatively committed CD34+CD90- cells. Our findings indicate that while VPA supports CD34+CD90+ cell expansion, the CD34+CD90+ cells derived from CD34+CD90- cells are functionally more differentiated than those derived directly from CD34+CD90+ cells, with increased mitochondrial mass and membrane potential, but reduced regenerative potential. These results emphasize the need for functional assessments of culture-expanded HSCs to accurately determine their therapeutic potential.

ETV2 is a pioneer factor that regulates cell fate decisions and direct reprogramming of the endothelial lineage. While ETV2 drives the cell fate conversion through epigenetic remodeling, its downstream targets also contribute to ETV2-mediated cell fate conversion. In this study, we defined Ecscr as a direct transcriptional target of ETV2 and a key regulator of ETV2-mediated cell reprogramming. Single-cell RNA sequencing analyses of ETV2-overexpressing embryoid body differentiation and embryonic fibroblast reprogramming revealed upregulation of Ecscr in ETV2-induced cell populations. ATAC-seq, ChIP-seq, gel shift, and transcriptional assays confirmed ETV2 binding to the Ecscr gene. In vivo analyses using 3.9 kb-Etv2-EYFP reporter transgenic mice and Etv2 null mice, in combination with single-cell RNA-seq of developing mouse embryos, further validated Ecscr as an ETV2 downstream target. Functionally, the knockdown of Ecscr significantly enhanced reprogramming rate, suggesting that Ecscr functions in a feedback mechanism to decrease the ETV2-mediated cell fate conversion. Mechanistically, Ecscr knockdown led to upregulation of Rptor, a core component of mTORC1 complex. The inhibition of mTORC1 signaling with rapamycin partially reversed the effect, supporting the notion that mTORC1 functions as a downstream mediator. Our findings uncover a novel ETV2 downstream target ECSCR that modulates ETV2-driven reprogramming through mTORC1 regulation, offering a target to improve endothelial reprogramming for regenerative applications.

Osteoradionecrosis of the jaws (ORNJ) is a severe aseptic complication of high-dose radiotherapy for head-and-neck cancers, characterized by chronic jawbone necrosis, functional impairment, and poor responses to traditional treatments (eg, hyperbaric oxygen and surgical resection) that fail to address its root pathophysiology (microcirculatory impairment, bone metabolism dysfunction). Its incidence is 1.2%-40% in patients receiving >60 Gy radiotherapy, especially with concurrent trauma. In recent years, stem cell therapy has garnered attention as a potential treatment for a variety of bone-related disorders, including the repair of bone defects, treatment of osteoarthritis, and mitigation of osteoporosis. Evidence from preclinical studies indicates that local transplantation of mesenchymal stem cells in rodent models of ORNJ significantly increases bone volume and bone mineral density. The therapeutic efficacy is primarily attributed to the cells' capacity for multidirectional differentiation, paracrine signaling, and immunomodulatory functions, highlighting their substantial potential for clinical translation. This narrative review synthesizes studies on stem cell therapy for ORNJ published from 2004 to 2024 (PubMed, Medline, Cochrane), with a focus on original research published in the most recent decade (2014-2024) to reflect the latest advances. This review consolidates ORNJ pathogenesis and stem cell mechanisms, identifies research gaps, and guides future efforts to standardize protocols and advance clinical translation.