STEM CELLS最新文献

The Ten-Eleven Translocases (Tet) family of DNA hydroxymethylases have recently been implicated in bone development, with Tet1 and Tet2 mediating Bone Marrow Stromal Cell (BMSC) growth and osteogenic differentiation. The present study investigated the effects of Tet1 and Tet2 deregulation on bone development and age-related bone loss, with respect to BMSC function. Histomorphometric and micro-CT analysis of skeletal parameters found significant reductions to trabecular structure and volume as well as reduced osteoblast numbers within the bone of Prx1:Cre driven Tet1 and Tet2 double knockout (TetDKO) mice at skeletal maturity. Moreover, these effects were exacerbated with age, particularly in male mice. In vitro, studies found a significant reduction in TetDKO BMSC osteogenic potential and a shift towards adipogenesis, as well as changes to DNA repair, proliferation, and senescence properties. RNA sequencing of BMSC derived from TetDKO male mice uncovered several differentially expressed genes, and an array of significantly enriched gene set pathways. Notably, Pappa2, involved in the regulation of IGF-1 signaling, was significantly differentially regulated, leading to a reduction in IGF-1 bioavailability and signaling in BMSC and differentiated osteoblasts. Furthermore, changes in mTOR activity in TetDKO animals indicated altered metabolic activity, differentiation, and proliferation capabilities of TetDKO BMSC. These findings indicate that Tet1 and 2 regulate the IGF-1 regulatory element, Pappa2, where deregulation of Tet1 and Tet2 in BMSC can disrupt this pathway leading to enhanced bone loss and premature aging. Targeting these novel regulatory pathways may offer new therapeutic approaches for the treatment of age-related bone loss.

Huntington's disease (HD) is a neurodegenerative disorder caused by an expansion of CAG repeats in exon 1 of the huntingtin (HTT) gene, resulting in a mutant HTT (mHTT) protein. Although mHTT is expressed in all tissues, it significantly affects medium spiny neurons (MSNs) in the striatum, resulting in their loss and the subsequent motor function impairment in HD. While HD symptoms typically emerge in midlife, disrupted MSN neurodevelopment is important. To explore the effects of mHTT on MSN development, we differentiated HD-induced pluripotent stem cells (iPSCs) and isogenic controls into neuronal stem cells, and then generated a developing MSN population encompassing early, intermediate progenitors, and nascent MSNs. Single-cell RNA sequencing revealed that the developmental trajectory of MSNs in our model closely emulated the trajectory of human fetal striatal neurons. However, in the HD MSN cultures, several crucial genes required for proper MSN maturation were downregulated, including members of the DLX family of transcription factors. Our analysis also uncovered a progressive dysregulation of multiple HD-related pathways as MSNs developed, including the NRF2-mediated oxidative stress response and mitogen-activated protein kinase signaling. Using the transcriptional profile of developing HD MSNs, we searched the L1000 dataset for small molecules that induce the opposite gene expression pattern. We pinpointed numerous small molecules with known benefits in HD models and previously untested novel molecules. A top candidate, Cerulenin, partially restored the DARPP-32 levels and electrical activity in HD MSNs, and also modulated genes involved in multiple HD-related pathways.

Olfactory sensory neurons (OSNs) in the olfactory epithelium (OE) are continuously replaced by neuroregeneration from basal stem cells. Acute inflammation destroys OSNs, causing hyposmia or anosmia, but leaves the basal stem cells intact. We previously found that ciliary neurotrophic factor (CNTF) is highly expressed in horizontal basal cells (HBCs) and the CNTF receptor is in globose basal cells (GBCs), which are the actively dividing cells that normally replace dying OSNs. Here, we investigated the role of CNTF in basal stem cell proliferation/differentiation and smell function recovery following methimazole-induced acute inflammatory OE injury. Methimazole increased inflammatory markers, TNFα, IL-6, and CD45, and depleted OSNs in the OE at 3 and 5 days. Simultaneously, CNTF and the GBC marker Mash1 were upregulated, suggesting that HBCs produced more CNTF, as validated using primary HBC cultures, to promote GBC proliferation. Methimazole increased GBC proliferation, as shown by the number of BrdU-labeled GBCs in CNTF+/+, but not in CNTF-/- littermate mice. Also, CNTF+/+ mice had higher levels of neuroregeneration and better smell function recovery than CNTF-/- littermates. This indicates that CNTF promotes GBC proliferation and promotes OE neuroregeneration and smell functional recovery. This study identifies the regenerative role of CNTF in HBCs and reveals the therapeutic potential to target CNTF signaling to improve olfactory neuroregeneration and functional recovery following injury.

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by disrupted epidermal barrier function and excessive immune activation. Conventional treatments using corticosteroids and immunosuppressants provide only temporary relief and often induce adverse side effects, highlighting the need for novel, effective therapy. In this study, we investigated the therapeutic potential of neural stem cell-derived extracellular vesicles (NSC-EVs) derived from NSC-derived conditioned medium (NSC-CM) in modulating inflammatory responses in AD. In vitro experiments using human keratinocytes (HaCaT) and murine macrophages (RAW264.7) showed that both NSC-CM and NSC-EVs can significantly decrease the expression of proinflammatory cytokines and chemokines, inhibit the phosphorylation of NF-κB, and reduce inducible nitric oxide synthase. In addition, topical application of NSC-CM and NSC-EVs alleviated atopic symptoms, reduced mast cell infiltration, and improved skin barrier integrity in a 2,4-dinitrochlorobenzene-induced AD mouse model. Proteomic analysis identified key proteins related to immune regulation and extracellular matrix remodeling in NSC-EVs, indicating their active role in mitigating inflammation and tissue repair. Altogether, our results demonstrated the potent anti-inflammatory effects of NSC-EVs, highlighting their potential to be a novel and effective therapeutic option for AD and other inflammation-related diseases.

Fibroblast activation protein-α (FAP) has been identified as an osteogenic suppressor and a potential drug target to treat osteoporosis. However, the direct role of FAP in osteoblast differentiation and the mechanism by which FAP works remains to be explored. In the current study we showed that FAP expression increased significantly during osteogenic and adipogenic differentiation of mesenchymal progenitor cells. Functional experiments revealed that FAP suppressed osteoblast differentiation and forced adipocyte formation from mesenchymal progenitor cells. Mechanistic exploration showed that FAP reduced the protein level of C-X-C motif chemokine ligand 12 (CXCL12) through directly degrading the latter. Consistently, the point mutation of the catalytic site rendered FAP fail to reduce CXCL12 protein level and fail to impact osteoblast and adipocyte differentiation. While CXCL12 activated canonical Wnt pathway, FAP inactivated canonical Wnt signaling to regulate differentiation of osteoblasts and adipocytes. CXCL12 was able to promote osteoblast differentiation while suppressing adipocyte differentiation, and attenuated the dysregulation of the differentiation tendencies induced by FAP. Taken as a whole, our study has demonstrated that FAP directly cleaves CXCL12 to inactivate canonical Wnt signaling, and therefore plays a direct role in regulating osteogenic and adipogenic differentiation of mesenchymal progenitor cells.

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.