STEM CELLS最新文献

Optogenetics holds great potential for diverse biological applications, including fundamental research, tissue engineering, and regenerative medicine, by enabling the precise spatial and temporal control of cellular signaling pathways. Transforming growth factor-beta (TGFβ), a multifunctional cytokine, is a critical regulator of cell proliferation, differentiation, and particularly chondrogenesis. Although TGFβ signaling is necessary for effective chondrogenic differentiation, previous studies have primarily relied on recombinant TGFβ ligand supplementation. In this study, we established an advanced optogenetic platform by knocking-in opto-TGFβ receptors in the AAVS1 locus of human embryonic stem cells (hESCs), enabling precise optogenetic activation of endogenous TGFβ signaling. Blue light illumination specifically activated TGFβ signaling, indicated by enhanced SMAD2 phosphorylation. Employing a three-dimensional pellet culture system, we demonstrated that direct optogenetic activation of TGFβ receptors, without exogenous ligand supplementation, is sufficient for robust chondrogenic differentiation of hESC-derived mesenchymal stem cells. The efficiency of optogenetic differentiation was comparable to conventional recombinant TGFβ protein treatment, evidenced by the expression of chondrogenic markers and deposition of cartilage-specific extracellular matrix components, including aggrecan and type II collagen. Our findings directly confirm the sufficiency and critical role of TGFβ receptor activation itself in chondrogenesis. Furthermore, this optogenetic approach provides a theoretical advantage by enabling noninvasive external modulation of TGFβ signaling post-transplantation, potentially facilitating further maturation and functional integration of transplanted chondrocytes. Thus, our results highlight a promising recombinant-protein-free strategy for use in cartilage tissue engineering and regenerative medicine.

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.

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.

Despite breakthroughs in molecularly targeted and immune therapies, the prognosis for patients with urinary bladder cancer (UBC) has remained unsatisfactory over the past few decades. Understanding the molecular underpinnings of UBC treatment refractoriness is crucial for identifying novel therapeutic targets and strategies. Cancer stemness plays a pivotal role in the oncogenesis and treatment resistance of UBC, while the underlying molecular regulatory mechanisms are poorly understood. We identified isoform 1 of ASPM (ASPM-i1) as the most upregulated stemness-associated factor in tumorigenic UBC cells, predominantly expressed by ALDH1+ stem-like cancer cells. Pairing genetic ASPM-i1 inhibition with standard chemotherapeutic agents used in the treatment of UBC, including cisplatin and gemcitabine, circumvents the treatment resistance of tumorigenic and stem-like UBC cells. Mechanistically, ASPM-i1 interacts with the Disheveled (DVL) and intracellular NOTCH proteins, thereby attenuating CUL3- or FBXW7-mediated ubiquitination and the subsequent proteasomal degradation. The regulatory module concomitantly enhances the activities and ligand responsiveness of the Wnt and Notch signaling pathways in UBC cells. As a result, ASPM-i1 inhibition sensitized tumorigenic UBC cells to chemotherapy in a NOTCH- and DVL-dependent manner. In human UBC tissues, ASPM-i1 shows substantial cell-to-cell heterogeneity and is upregulated in a subset (46.4%) of tumors, correlating with poor clinical prognosis. This study reveals a crucial co-regulatory module of Notch and Wnt signaling that mediates stemness and chemotherapy resistance in tumorigenic UBC cells; its inhibition provides a novel approach to enhance chemosensitivity and improve therapeutic outcomes in human UBC.

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.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and malignant cancer of the pancreas characterized by various genetic mutations and metabolic dysregulations. Stem cells play a critical role in the initiation, progression, and resistance of PDAC due to their plasticity, self-renewal capabilities, and ability to drive tumorigenesis. The gut microbiome, a diverse ecosystem of microorganisms, has a profound influence on systemic health, including the development of cancer. Recent studies have highlighted that the microbiome composition within the tumor can modulate stem cell behavior by shaping the tumor microenvironment (TME), enhancing cellular plasticity, and promoting the stemness properties of PDAC. In this review, we explore the potential crosstalk between the gut microbiome and PDAC stem cells, focusing on how microbiome-derived signals impact stem cell maintenance, inflammation, metastasis, TME modulation, and metabolic reprogramming.

Background: Umbilical cord blood (UCB) and umbilical cord tissue (UCT) are non-invasive, readily available sources of stem cells with significant potential for regenerative medicine and hematopoietic transplantation. While hematopoietic stem cells from UCB and mesenchymal stem cells from both UCB and UCT are clinically applied, other cord-derived populations remain under investigation, offering novel therapeutic opportunities alongside translational challenges.

Main body: This review synthesizes current knowledge on stem cell populations derived from UCB and UCT. Hematopoietic and mesenchymal stem cells have established clinical roles, whereas unrestricted somatic stem cells, embryonic-like stem cells, MUSE cells, and multipotent progenitor cells show preclinical promise. These populations differ in differentiation potential, therapeutic application, and biological characteristics. Translational barriers include limited cell numbers, variable engraftment, immune compatibility, and challenges in long-term preservation. Emerging strategies, such as ex vivo expansion, co-transplantation, and nanoparticle-assisted delivery, aim to enhance efficacy, precision, and safety.

Conclusion: This narrative review highlights both opportunities and challenges of umbilical cord stem cell therapies. Standardized protocols, interdisciplinary collaboration, and continued innovation are essential to optimize clinical outcomes and fully realize the translational potential of these diverse populations.

A reduction in circulating endothelial progenitor cells (EPCs) comprise an important part of vascular aging. However, the underlying mechanisms that mediate this EPC decline remain unclear. Here, we demonstrate a novel molecular mechanism where aging increases inhibitory T cell subsets and impairs SDF1-mediated increase of circulating EPCs. SomaScan proteomics and western blot analysis revealed FABP4 as the top upregulated protein in plasma and was also increased in the bone marrow in aging. Importantly, treatment with FABP4 in bone marrow cells increased inhibitory T cells while decreased SDF-1 receptor, CXCR4 in EPCs, whereas blocking FABP4 signaling by BMS309403 or depleting these T cells restored surface expression of CXCR4 in EPCs. Notably, FABP4-mediated decrease of circulating EPC in aging were restored by therapeutic administration of mitochondria, wherein plasma FABP4 was decreased along with reducing inhibitory T cell induction in bone marrow and increasing circulating EPCs in older mice. Collectively, these findings provide new insight into the involvement of age-associated T cell immunity in EPC dysregulation, and FABP4 may be a therapeutic target to detain vascular aging.

Hepatic macrophages, encompassing embryonic Kupffer cells (emKCs) and monocyte-derived macrophages (MoMFs), are recognized as important regulators of hepatic homeostasis and key players in the pathogenesis of liver diseases such as metabolic dysfunction-associated steatotic liver disease (MASLD). Emerging research focuses on the critical role of hepatic macrophages in mediating liver repair and regeneration following injury, where they closely interact with hepatocytes as well as hepatic stellate cells (HSCs) to regulate inflammation, fibrosis, tissue remodeling, and regeneration. The latest single-cell and spatial omics technologies have profoundly deepened our understanding of the hepatic immune response, revealing the remarkable phenotypic and spatial heterogeneity of macrophages, including distinct subsets such as lipid-associated macrophages (LAMs) within steatotic and fibrotic regions. Macrophage subsets sense systemic (e.g. gut-liver axis, adipose tissue) and local stress signals and orchestrate disease-defining cellular responses in hepatocytes, HSC, and other immune cells. Dynamic tools such as intravital microscopy have further unveiled functional properties in the spatial context hitherto unknown. Herein, we review the multifaceted roles of hepatic macrophages in liver injury and repair, with an emphasis on their role in steatosis, inflammation, fibrosis, and regeneration. We also discuss how these insights may inform the development of novel macrophage-targeted therapeutic interventions.

Background: The precise timing of stem cell specification and niche formation during murine incisor development is poorly understood, and it is unclear whether these processes occur simultaneously or in a sequential manner. Functional dental epithelial stem cells are marked by the expression of Sox2, a transcription factor that is broadly expressed in the dental epithelium at the dentition onset and restricted to stem cells in fully developed incisor.

Methods: Using genetic lineage tracing in Sox2CreERT2/+; R26RmT/mG and Sox2CreERT2/+; R26RtdT/+ embryos along with a single-cell RNA sequencing at different stages of incisor development, we investigated the timing of the stem cell specification and its temporal relationship with niche formation.

Results: Our results reveal the presence of a Sox2-expressing stem cell-like population prior to formation of the functional niche. These cells localize to the leading edge of the advancing incisor epithelium where they are maintained in an undifferentiated state. Our data demonstrate presence of actomyosin network and a generation of a contractile tension, which helps confine Sox2+ stem cells to the leading edge.

Conclusion: This mechanical confinement likely plays an important role in maintaining their stemness until the niche is functionally and structurally established. Partial or complete disruption of the actomyosin network disables the clustering of Sox2-expressing cells, potentially triggering their premature differentiation, and ultimately leads to impaired formation of the functional stem cell niche and abnormal growth of the incisor.