STEM CELLS最新文献

As the most abundant internal modification on mRNAs, N6-methyladenosine (m6A) has been discovered to be involved in different biological processes. Mostly determined by m6A methyl-transferases (m6A writers) and demethylases (m6A erasers), different cell types possess differential m6A profiles of transcriptomes. However, the interpretation of the m6A-encoded epitranscriptomic information needs m6A readers to bind and recruit different machinery for regulating the target mRNAs, which in turn, may regulate cell fates. The functions of the m6A readers in the regulation of the maintenance and differentiation of human embryonic stem cells (hESCs) remain largely unknown. In this study, we deleted the whole genomic region of the m6A reader YTHDF2 and discovered that YTHDF2 is dispensable for the maintenance, but important for the differentiation of hESCs, especially for the differentiation towards ectoderm. Furthermore, we identified the m6A-modified ROBO1 mRNAs as potential targets by YTHDF2 in regulating hESC to neuroectoderm differentiation. This study reveals the potential roles of the m6A reader YTHDF2 in regulating the specification of neuroectodermal cell fate.

Mesenchymal stem cells (MSCs) are pivotal in regenerative medicine, particularly for their efficacy in tissue repair. However, sourcing high-quality MSCs presents challenges due to limited availability and compromised function. Induced pluripotent stem cells (iPSCs) offer a promising alternative for generating MSCs through specific differentiation protocols. In this study, we employed rabbit iPSCs to explore their capacity for differentiation into MSCs, facilitated by the use of SB431542, a TGF-β signaling inhibitor. Upon treatment with SB431542, rabbit iPSCs underwent embryoid body (EB) formation, leading to successful differentiation into the mesenchymal lineage. Our results demonstrated significant upregulation of mesodermal markers while reduced expression of ectodermal and endodermal markers, confirming effective MSC differentiation. Additionally, in a mouse wound healing model, rabbit iPSC-derived MSCs significantly enhanced wound closure compared to controls. These findings highlight the potential of SB431542 in generating functional iPSC-derived MSCs, offering valuable applications in regenerative medicine across species.

The heterogeneity of stem cells is a significant factor inhibiting their clinical application, as different cell subpopulations may exhibit substantial differences in biological functions. We performed single-cell sequencing on human umbilical cord mesenchymal stem cells (HUMSCs) from 3 donors of different gestational ages (22 + 5, 28, and 39 weeks). We also compared the data with single-cell sequencing data from BMSCs from 2 public databases. The content of CD146+Nestin+ MSCs in preterm HUMSCs (22 + 5W: 30.2%, 28W: 25.8%) was higher than that in full-term HUMSCs (39W: 0.5%) and BMSCs (BMSC1: 0, BMSC2: 0.9%). Cell cycle analysis indicated a higher proportion of cells in the proliferative G2M phase in CD146+Nestin+ MSCs (40.8%) compared to CD146+Nestin- MSCs (20%) and CD146-Nestin- MSCs (12.5%). The degree of differentiation assessment suggested that CD146+Nestin+ MSCs exhibited lower differentiation than other cell subpopulations. Differential gene analysis revealed that CD146+Nestin+ MSCs overexpressed immune regulation-related factors. GO and KEGG enrichment analysis of modules identified by weighted gene co-expression network analysis suggested enrichment in pathways related to cellular immune regulation, antimicrobial activity, and proliferation. Immune-related gene analysis indicated that CD146+Nestin+ MSCs exhibited expression of multiple immune-related genes associated with "antimicrobials," "cytokines," and "cytokine receptors." Gene regulatory network analysis revealed high expression of immune-related regulators RELB, GAPB1, and EHF in CD146+Nestin+ MSCs. Our study provides a single-cell atlas of preterm HUMSCs, demonstrating the expression of CD146+Nestin+ MSCs across different tissues and confirming their advantages in cellular proliferation, antimicrobial activity, immune regulation, and low differentiation at the RNA level. This contributes valuable insights for the clinical application of HUMSCs.

Background: Extracellular vesicles (EVs) derived from mesenchymal stem cells have shown promise in treating inflammation. This study investigates whether preconditioning feline adipose-derived stem cells (FeASCs) with inflammatory cytokines, specifically IFN-γ and TNF-α, enhances the anti-inflammatory efficacy of MSC-derived EVs.

Objective: We hypothesize that cytokine-primed FeASCs will produce EVs with improved anti-inflammatory properties and that this preconditioning will affect mitochondrial dynamics to enhance EV therapy effectiveness.

Methods: FeASCs were exposed to a TNF-α/IFN-γ combination to mimic a pro-inflammatory milieu favoring ASCs' immunosuppressive phenotype. We analyzed morphological, metabolic, and immunomodulatory characteristics of native and cytokine-primed FeASCs. EVs were assessed for anti-inflammatory and mitochondrial-related markers. We also evaluated mitochondrial function and apoptosis markers in cytokine-primed cells.

Results: Cytokine priming led to significant morphological changes in FeASCs, including enhanced cell projections and increased apoptosis. EVs from cytokine-primed FeASCs exhibited a heightened immunomodulatory profile, with increased expression of both pro-inflammatory and anti-inflammatory mediators. Transcriptomic analysis of these EVs revealed the upregulation of genes associated with cell proliferation, survival, and apoptosis. Mitochondrial function was impaired in cytokine-primed cells, but mitochondrial morphology remained unchanged. EVs from these cells contained higher levels of mitochondrial-related transcripts, indicating a compensatory response.

Conclusions: Cytokine-primed FeASCs generate EVs with enhanced immunomodulatory potential, highlighting their therapeutic promise. However, further research is needed to validate their efficacy and safety and refine preconditioning strategies to optimize EV-based therapies for inflammatory conditions. These advancements could pave the way for broader applications in regenerative medicine.

Mesenchymal stem cells (MSCs) are multipotent stem cells that have a chondrogenic differentiation capacity. However, the molecular mechanism underlying the chondrogenic differentiation of MSCs has not been fully elucidated, which hinders further development of MSC-based cell therapies for cartilage repair in the clinic. Here, we showed that the E3 ubiquitin ligase Trim63 positively regulates the chondrogenic differentiation of MSCs by catalyzing the K27-linked cysteine ubiquitination of Myh11. Trim63 directly interacts with Myh11 and catalyzes K27-linked ubiquitination of cys382. Mutation of cys382 diminishes Trim63-catalyzed K27-linked ubiquitination and chondrogenic differentiation of MSCs. A deficiency in Trim63 significantly impairs the chondrogenic differentiation of MSCs. Trim63 enhances the repair of articular cartilage defects in vivo. Taken together, the results of our study demonstrated that Trim63 promotes the chondrogenic differentiation of MSCs by catalyzing K27-linked cysteine ubiquitination of Myh11, which provides an alternative therapeutic target for cartilage regeneration and repair.

SARS-CoV2, severe acute respiratory syndrome coronavirus 2, is frequently associated with neurological manifestations. Despite the presence of mild to severe CNS-related symptoms in a cohort of patients, there is no consensus whether the virus can infect directly brain tissue or if the symptoms in patients are a consequence of peripheral infectivity of the virus. Here, we use long-term human stem cell-derived cortical organoids to assess SARS-CoV2 infectivity of brain cells and unravel the cell-type tropism and its downstream pathological effects. Our results show consistent and reproducible low levels of SARS-CoV2 infection of astrocytes, deep projection neurons, upper callosal neurons, and inhibitory neurons in 6 months of human cortical organoids. Interestingly, astrocytes showed the highest infection rate among all infected cell populations which led to changes in their morphology and upregulation of SERPINA3, CD44, and S100A10 astrogliosis markers. Further, transcriptomic analysis revealed overall changes in expression of genes related to cell metabolism, astrogliosis and, inflammation and further, upregulation of cell survival pathways. Thus, local and minor infectivity of SARS-CoV2 in the brain may induce widespread adverse effects and lead to the resilience of dysregulated neurons and astrocytes within an inflammatory environment.

Progressive endothelial cell injury of retinal vascular is a vital factor in diabetic retinopathy (DR) pathogenesis. Mesenchymal stem cells-derived small extracellular vesicles (MSC-sEVs) showed beneficial effects on DR. However, the effects of MSC-sEVs on endothelial dysfunction of DR and the mechanism is still unclear. In this study, MSC-sEVs mitigated retinal blood-retina barrier (BRB) impairment in rats with streptozotocin (STZ)-induced DR by reducing ferroptosis in vivo and in vitro. MSC-sEVs miRNA sequencing analysis revealed that miR-125b-5p may mediate human retina microvascular endothelial cells (HRMECs) ferroptosis and P53 as a downstream target based on dual-luciferase reporter assays. Silencing miR-125b-5p in MSC-sEVs reversed the therapeutic effects of MSC-sEVs on rats with DR and advanced glycation end products (AGEs)-treated HRMECs. Additionally, overexpression of miR-125b-5p could diminish ferroptosis in HRMECs, and this effect could be effectively reversed by overexpressing P53. This study indicated the potential therapeutic effect of MSC-sEVs on vascular endothelial function maintenance and that the delivery of sEVs carrying miR-125b-5p could prevent endothelial cell ferroptosis by inhibiting P53, thereby protecting the BRB.

In the past, the mammal central nervous system (CNS) was assumed to lack the capacity for neural repair. However, increasing evidence shows that the CNS has repair capacity after injury. The migratory capacity of neural stem/progenitor cells (NSPCs) from subventricular zones (SVZ) is limited, and the precise repair mechanism active after ischemic stroke remains unknown. Consequently, it remains unclear how neural regeneration occurs in regions far from the SVZ, such as the cortex, especially given that these NSPCs can only migrate toward ischemic areas within specific brain regions. Nonetheless, using a mouse model of ischemic stroke with ischemic areas limited to the ipsilateral side of the cortex, we previously identified regionally-derived stem cells, injury/ischemia-induced stem cells (iSCs), within poststroke areas. Moreover, we showed that iSCs, which had the potential to differentiate into electrophysiologically functional neurons, were present within ischemic areas in poststroke human brains. This indicates that ischemic insult can activate locally-derived stem cells, even in nonneurogenic zones, and that iSCs can help achieve neural regeneration after ischemic stroke. However, inflammatory cells typically fill ischemic areas impairing neural regeneration in these areas. Here, we present the origin, characterization, and roles of iSCs based on our recent research. In addition, we discussed the potential of iSC-based therapies to achieve neural regeneration after ischemic stroke.