Stem cells and development最新文献

Although enhanced fibroblast growth factor (FGF) signaling has been demonstrated to be crucial in many cases of syndromic cleft palate caused by tongue malposition in humans, animal models that recapitulate this phenotype are limited, and the precise mechanisms remain elusive. Mutations in FGF9 with the effect of either loss- or gain-of-function effects have been identified to be associated with cleft palate in humans. Here, we generated a mouse model with a transgenic Fgf9 allele specifically activated in cranial neural crest cells, aiming to elucidate the gain-of-function effects of Fgf9 in palatogenesis. We observed cleft palate with 100% penetrance in mutant mice. Further analysis demonstrated that no inherent defects in the morphogenic competence of palatal shelves could be found, but a passively lifted tongue prevented the elevation of palatal shelves, leading to the cleft palate. This tongue malposition was induced by posterior spatial confinement that was exerted by temporomandibular joint (TMJ) dysplasia characterized by a reduction in Sox9+ progenitors within the condyle and a structural decrease in the posterior dimension of the lower jaw. Our findings highlight the critical role of excessive FGF signaling in disrupting spatial coordination during palate development and suggest a potential association between palatal shelf elevation and early TMJ development.

This study investigates the characteristics of cardiac mesenchymal stem cell-like cells (CMSCLCs) isolated from the right atrial appendage of human donors with ischemia and a young patient with endocarditis (NE-CMSCLCs). Typical CMSCLCs from ischemic heart patients were derived from coronary artery bypass grafting procedures and compared against bone marrow mesenchymal stromal cells (BM-MSCs). NE-CMSCLCs had a normal immunophenotype, but exhibited enhanced osteogenic differentiation potential, rapid proliferation, reduced senescence, reduced glycolysis, and lower reactive oxygen species generation after oxidative stress compared with typical ischemic CMSCLCs. These differences suggest a unique functional status of NE-CMSCLCs, influenced by the donor health condition. Despite large variances in their paracrine secretome, NE-CMSCLCs retained therapeutic potential, as indicated by their ability to protect hypoxia/reoxygenation-injured human cardiomyocytes, albeit less effectively than typical CMSCLCs. This research describes a unique cell phenotype and underscores the importance of donor health status in the therapeutic efficacy of autologous cardiac cell therapy.

The origin of breast cancer (BC) has traditionally been a focus of medical research. It is widely acknowledged that BC originates from immortal mammary stem cells and that these stem cells participate in two division modes: symmetric cell division (SCD) and asymmetrical cell division (ACD). Although both of these modes are key to the process of breast development and their imbalance is closely associated with the onset of BC, the molecular mechanisms underlying these phenomena deserve in-depth exploration. In this review, we first outline the molecular mechanisms governing ACD/SCD and analyze the role of ACD/SCD in various stages of breast development. We describe that the changes in telomerase activity, the role of polar proteins, and the stimulation of ovarian hormones subsequently lead to two distinct consequences: breast development or carcinogenesis. Finally, gene mutations, abnormalities in polar proteins, modulation of signal-transduction pathways, and alterations in the microenvironment disrupt the balance of BC stem cell division modes and cause BC. Important regulatory factors such as mammalian Inscuteable mInsc, Numb, Eya1, PKCα, PKCθ, p53, and IL-6 also play significant roles in regulating pathways of ACD/SCD and may constitute key targets for future research on stem cell division, breast development, and tumor therapy.

Adipose stem cells are considered one of the primary drivers of autologous fat graft biological activity and survival. We have previously demonstrated that hormonally active VD3 improved adipose stem cell viability in ex vivo and in vivo fat grafting models. In this study, we evaluated the inactive form of VD3 (cholecalciferol) on adipose stromal cell (ASC) phenotype during hypoxia and the subsequent effect on human fat graft retention in the xenograft model. Lipoaspirate collected from six human donors was used for ex vivo particle culture studies and isolated ASC studies. Adipose particles were treated with increasing doses of VD3 to determine impact on ASC survival. Expanded stromal cells were treated with VD3 during hypoxic culture and assessed for viability, apoptosis, mitochondrial activity, and nitric oxide (NO) release via caspase, DAF-FM, or TMRM. Finally, 40 Nu/J mice receiving bilateral dorsal human lipoaspirate were treated thrice weekly with (1) vehicle control, (2) 50 ng calcitriol, (3) 50 ng VD3, (4) 500 ng VD3, and (5) 5,000 ng VD3 for 12 weeks, n = 8 per group. Graft weight, volume, and architecture were analyzed. Adipose particles treated with dose-escalating VD3 had significantly increased ASC viability compared with control (P < 0.01). Under hypoxia, ASCs treated with 1 nM VD3 had significantly greater viability than untreated and pretreated cells (P < 0.01, P < 0.01) and significantly lower apoptosis-to-viability ratio (P < 0.01). ASCs pretreated with 1 nM VD3 had significantly lower NO release (P < 0.05) and lower mitochondrial polarization (P < 0.05) compared with controls. In vivo results showed mice receiving 5,000 ng VD3 had significantly greater graft weight (P < 0.05) and volume (P < 0.05) after 12 weeks of treatment compared with controls. Grafts had enhanced neovascularization, intact adipocyte architecture, and absence of oil cysts. VD3 is an over-the-counter nutritional supplement with a known safety profile in humans. Our xenograft model suggests administering VD3 at the time of surgery may significantly improve fat graft retention.

Prostaglandin E2 (PGE2) has recently gained attention in the field of regenerative medicine because of the beneficial effects of this molecule on stem cell proliferation and migration. Furthermore, PGE2 has the ability to mitigate immune rejection and fibrosis. In the colon and kidney, PGE2 induces YAP1, a transcription factor critical for cardiac regeneration. Establishing a similar connection in stem cells that can be transplanted in the heart could lead to the development of more effective therapeutics. In this report, we identify the effects of PGE2 on neonatal Islet-1+ stem cells. These stem cells synthesize PGE2, which functions by stimulating the transcription of the extracellular matrix protein Agrin. Agrin upregulates YAP1. Consequently, both YAP1 and Agrin are induced by PGE2 treatment. Our study shows that PGE2 upregulated the expression of both YAP1 and Agrin in Islet-1+ stem cells through the EP4 receptor and stimulated proliferation using the same mechanisms. PGE2 administration further elevated the expression of stemness markers and the matrix metalloproteinase MMP9, a key regulator of remodeling in the extracellular matrix post-injury. The expression of PGE2 in neonatal Islet-1+ cells is a factor which contributes to improving the functional efficacy of these cells for cardiac repair.

Intravascularly transplanted bone marrow cells, including bone marrow mononuclear cells (BM-MNC) and mesenchymal stem cells, transfer water-soluble molecules to cerebral endothelial cells via gap junctions. After transplantation of BM-MNC, this fosters hippocampal neurogenesis and enhancement of neuronal function. Herein, we report the impact of transplanted BM-MNC on neural stem cells (NSC) in the brain. Surprisingly, direct transfer of water-soluble molecules from transplanted BM-MNC and peripheral mononuclear cells to NSC in the hippocampus was observed already 10 min after cell transplantation, and transfer from BM-MNC to GFAP-positive cortical astrocytes was also observed. In vitro investigations revealed that BM-MNC abolish the expression of hypoxia-inducible factor-1α in astrocytes. We suggest that the transient and direct transfer of water-soluble molecules between cells in circulation and NSC in the brain may be one of the biological mechanisms underlying the repair of brain function.

There are multiple methods to prepare lipoaspirate for autologous fat transfer; however, graft retention remains unpredictable. The purpose of this study was to compare the cellular and protein composition of adipose grafts and the stromal vascular fraction (SVF) resulting from three common techniques to prepare adipose grafts. Adipose grafts were harvested from healthy donors and processed via three techniques: centrifugation (C), a single-filter (SF) device, and a double-filtration (DF) system. Part of each graft was analyzed or further processed to isolate the SVF. Cell viability, surface markers, cytokine, and growth factors were compared between the graft and SVF as well as adipose-derived stem cells (ASCs). Overall, we found variations across the three processing techniques and among the graft components (ASCs, SVF, and fat). Cell viability within the grafts was similar (94.6%, 92.3%, and 93.6%; P = 0.93). The trend was a greater percentage of ASCs from SF versus DF or centrifugation (6.95%, 4.63%, and 1.93%, respectively, P = 0.06). Adipogenic markers (adiponectin and leptin) were similar among all three grafts (P = 0.45). Markers of tissue remodeling were greatest in the SVF compared with fat and ASCs, regardless of processing technique. There was higher relative expression of MMP-9 (2×), Extracellular matrix metalloproteinase inducer (EMMPRIN) (2.5×), endoglin (5×), and IL-8 (1.5×) in the SVF (P < 0.005). Our study identified differences in cytokine expression in adipose grafts and the SVF, particularly in cytokines important in inflammation and wound healing. These secretomes may impact graft retention and fat necrosis and have the potential implications in cell-assisted lipotransfer. There were no significant differences between the final products of any of the processing techniques.

The therapeutic potential of autologous stem cell transplantation for heart repair diminishes in the elderly due to stem cell aging. Rejuvenating aged stem cells to enhance their protective effects on injured cardiomyocytes is crucial for aging patients with heart failure. In this study, we aimed to investigate whether neuron-derived neurotrophic factor (NDNF) over-expression improves the protective effect of aged stem cells for injured cardiomyocytes and explore the underlying mechanism. Human bone marrow was collected from both young and old patients, and bone marrow mesenchymal stem cells (BMSCs) were cultured. Lentivirus expression vectors carrying NDNF genes were used to transfect aged BMSCs. Fatal hypoxia-induced injury in H9C2 cells served as an in vitro ischemia model. The conditioned medium from different BMSC groups was applied to assess the beneficial effects on hypoxia-induced damage in myocardial H9C2 cells. Results revealed that the conditioned medium of NDNF over-expressed old BMSCs increased H9C2 cell viability and reduced oxidative stress and apoptosis levels under fatal hypoxia. NDNF over-expressed old BMSCs exhibited an antiapoptotic role by upregulating the antiapoptotic gene Bcl-2 and downregulating the proapoptotic genes Bax. Additionally, the protective effects were mediated through the elevation of phosphorylated AKT. Our data support the promise of NDNF as a potential target to enhance the protective effects of autologous aged BMSCs on ischemic cardiomyocytes and then improve the curative effects of stem cell for ischemic heart injury in aged patients.

Nonalcoholic fatty liver disease (NAFLD) is a serious disease. There are no specific drugs for it, in part because of the lack of effective models to aid drug development. However, it has been shown that three-dimensional organoid culture systems can reproduce the organ structure and maintain the gene expression profile of the original tissue. Therefore, we aimed to construct NAFLD models from liver organoids for pharmacological and mechanism studies. We successfully observed morphological changes in normal liver tissue in mouse liver organoids with positive albumin (ALB) expression and potential for differentiation toward hepatocyte-like cells. The mRNA expression of the hepatocyte markers ALB and hepatocyte nuclear factor 4 alpha increased after liver organoid differentiation. We observed free fatty acid (FFA)-induced lipid accumulation in organoids with significant increases in alanine aminotransferase, aspartate aminotransferase, total bilirubin, and triglyceride levels. Moreover, FFA-induced inflammatory cytokines (interleukin-6, tumor necrosis factor-α, and nitric oxide) and fibrosis indicators (collagen type I α1 and laminin α1) were also increased. In addition, RNA sequencing results showed that the expression of key genes [nucleotide oligomerization domain-like receptor (NLR) family apoptosis inhibitory protein, interferon regulatory factor (IRF) 3, and IRF7] involved in NAFLD metabolic abnormalities and insulin resistance in the NLR signaling pathway was altered after FFA induction of the liver organoids. Finally, we found that JC2-11 and lanifibranor limited the FFA-induced increase in oil-red lipid droplets, liver damage, inflammation, and liver fibrosis. In conclusion, tissue structure, gene expression, and the response of mouse liver organoids to drugs can partially mimic in vivo liver tissue. Liver organoids can successfully construct NAFLD models for drug discovery research.

Prolonged tissue ischemia and inflammation lead to organ deterioration and are often accompanied by microvasculature rarefaction, fibrosis, and elevated systemic Activin A (ActA), the level of which frequently correlates with disease severity. Mesenchymal stromal cells are prevalent in the perivascular niche and are likely involved in tissue homeostasis and pathology. This study investigated the effects of inflammatory cells on modulation of phenotype of adipose mesenchymal stromal cells (ASC) and the role of ActA in this process. Peripheral blood mononuclear cells were activated with lipopolysaccharide (activated peripheral blood mononuclear cells [aPBMC]) and presented to ASC. Expression of smooth muscle/myofibroblast markers, ActA, transforming growth factors beta 1-3 (TGF_β1-3), and connective tissue growth factor (CTGF) was assessed in ASC. Silencing approaches were used to dissect the signaling cascade of aPBMC-induced acquisition of myofibroblast phenotype by ASC. ASC cocultured with aPBMC or exposed to the secretome of aPBMC upregulated smooth muscle cell markers alpha smooth muscle actin (αSMA), SM22α, and Calponin I; increased contractility; and initiated expression of ActA. Interleukin (IL)-1β was sufficient to replicate this response, whereas blocking IL-1β eliminated aPBMC effects. ASC-derived ActA stimulated CTGF and αSMA expression in ASC; the latter independent of CTGF. Induction of αSMA in ASC by IL-1β or ActA-enriched media relied on extracellular enzymatic activity. ActA upregulated mRNA levels of several extracellular matrix proteins in ASC, albeit to a lesser degree than TGF_β1, and marginally increased cell contractility. In conclusion, the study suggests that aPBMC induce myofibroblast phenotype with weak fibrotic activity in perivascular progenitors, such as ASC, through the IL-1β-ActA signaling axis, which also promotes CTGF secretion, and these effects require ActA extracellular enzymatic processing.