Mesenchymal stem cells (MSCs) hold great promise for the treatment of difficult diseases. As MSCs represent a rare cell population, ex vivo expansion of MSCs is indispensable to obtain sufficient ...amounts of cells for therapies and tissue engineering. However, spontaneous differentiation and aging of MSCs occur during expansion and the molecular mechanisms involved have been poorly understood.
Human MSCs in early and late passages were examined for their expression of genes involved in osteogenesis to determine their spontaneous differentiation towards osteoblasts in vitro, and of genes involved in self-renewal and proliferation for multipotent differentiation potential. In parallel, promoter DNA methylation and hostone H3 acetylation levels were determined. We found that MSCs underwent aging and spontaneous osteogenic differentiation upon regular culture expansion, with progressive downregulation of TERT and upregulation of osteogenic genes such as Runx2 and ALP. Meanwhile, the expression of genes associated with stem cell self-renewal such as Oct4 and Sox2 declined markedly. Notably, the altered expression of these genes were closely associated with epigenetic dysregulation of histone H3 acetylation in K9 and K14, but not with methylation of CpG islands in the promoter regions of most of these genes. bFGF promoted MSC proliferation and suppressed its spontaneous osteogenic differentiation, with corresponding changes in histone H3 acetylation in TERT, Oct4, Sox2, Runx2 and ALP genes.
Our results indicate that histone H3 acetylation, which can be modulated by extrinsic signals, plays a key role in regulating MSC aging and differentiation.
Background and Purpose
Intravascular injection of mesenchymal stem cells (MSCs) has been found to cause considerable vascular obstructions which may lead to serious outcomes, particularly after ...intra-arterial injection. However, the underlying mechanisms have been poorly understood.
Methods
In this study, we fractionated MSCs that had been cultured in monolayer for six passages into small (average diameter = 17.9 μm) and large (average diameter 30.4 μm) populations according to their sizes, and examined their vascular obstructions after intra-internal carotid artery injection in rats and mice in comparison with MSCs derived from 3D spheroids which were uniformly smaller in size (average diameter 12.6 μm).
Results
We found that 3D MSCs did not cause detectable infarct in the brain as evidenced by MRI scan and TTC stain, 2D MSCs in small size caused a microinfarct in one of five animals, which was co-localized to the area of entrapped MSCs (labeled with DiI), while 2D MSCs in large size caused much larger infarcts in all five animals, and substantial amounts of DiI-positive MSCs were found in the infarct. Meanwhile, corresponding neurological defects were observed in the animals with stroke. In consistence, injection of 2D MSCs (average diameter 26.5) caused a marked loss of cortical neurons and their axons in Thy1-GFP transgenic mice and the activation of microglia in CX3CR1-GFP transgenic mice in the area with MSC entrapment.
Conclusions
Our results suggest that the size of MSCs is a significant cause of MSC caused vascular obstructions and stroke.
A growing body of preclinical evidence suggests that mesenchymal stem cells (MSCs) are effective for the structural and functional recovery of the infracted heart. Accordingly, clinical trials are ...underway to determine the benefit of MSC-based therapies. While systemic administration of MSCs is an attractive strategy, and is the route currently used for the administration of MSCs in clinical studies for myocardial infarction, the majority of infused cells do not appear to localize to infracted myocardium in animal studies. Recently, important progress has been made in identifying chemokine receptors critical for the migration and homing of MSCs. Here, we review recent literature regarding mechanisms of MSC homing and recruitment to the ischemic myocardium, and discuss potential influences of low engraftment rates of systemically administered MSCs to the infracted heart tissue on the effects of MSC-based therapies on myocardial infarction.
Our understanding of the role of bone marrow (BM)‐derived cells in cutaneous homeostasis and wound healing had long been limited to the contribution of inflammatory cells. Recent studies, however, ...suggest that the BM contributes a significant proportion of noninflammatory cells to the skin, which are present primarily in the dermis in fibroblast‐like morphology and in the epidermis in a keratinocyte phenotype; and the number of these BM‐derived cells increases markedly after wounding. More recently, several studies indicate that mesenchymal stem cells derived from the BM could significantly impact wound healing in diabetic and nondiabetic animals, through cell differentiation and the release of paracrine factors, implying a profound therapeutic potential. This review discusses the most recent understanding of the contribution of BM‐derived noninflammatory cells to cutaneous homeostasis and wound healing. STEM CELLS 2010;28:905–915
MicroRNAs (miRNAs) are short non-coding RNAs involved in post-trascriptional regulation of gene expression and diverse biological activities. They are crucial for self-renewal and behavior of ...embryonic stem cells, but their role in mesenchymal stem cells has been poorly understood. Recently emerging evidence suggests that miRNAs are closely involved in controlling key steps of mesenchymal stem cell differentiation into certain cell lineages. This review focuses on miRNAs identified recently that regulate mesenchymal stem cell differentiation and other activities.
Mesenchymal stem cells (MSCs) are largely entrapped in the lungs after intravenous delivery. The underlying mechanisms have been poorly understood. Flow cytometry and Western blot analysis showed ...that the expression levels of many integrins such as β1, α5, and αVβ3 in MSCs increased markedly upon cultured expansion in 2D monolayers, whose ligands fibronectin and vitronectin were detected on the surface of vascular endothelial cells in the lungs by immunostaining and flow cytometry. Blockade of integrin β1, integrin α5, or integrins αVβ3 with functional blocking antibodies significantly decreased the amount of MSCs entrapped in the lungs following intravenous infusion as determined by real-time PCR and histological analysis; meanwhile, corresponding increases in the levels of circulating MSCs in the blood and MSCs homed to the ischemic myocardium and inflamed ear were found. Intriguingly, a short period of 3D spheroid culture of MSCs, which had been expanded for several passages in monolayers, substantially reduced the expression levels of many integrins and the number of MSCs entrapped in the lungs. Our results indicate that the excess expression and activation of integrins is a significant cause of lung entrapment of MSCs.
Mesenchymal stem cells (MSCs), in addition to their multilineage differentiation, exert immunomodulatory effects on immune cells, even dendritic cells (DCs). However, whether they influence the ...destiny of full mature DCs (maDCs) remains controversial. Here we report that MSCs vigorously promote proliferation of maDCs, significantly reduce their expression of Ia, CD11c, CD80, CD86, and CD40 while increasing CD11b expression. Interestingly, though these phenotypes clearly suggest their skew to immature status, bacterial lipopolysaccharide (LPS) stimulation could not reverse this trend. Moreover, high endocytosic capacity, low immunogenicity, and strong immunoregulatory function of MSC-treated maDCs (MSC-DCs) were also observed. Furthermore we found that MSCs, partly via cell-cell contact, drive maDCs to differentiate into a novel Jagged-2–dependent regulatory DC population and escape their apoptotic fate. These results further support the role of MSCs in preventing rejection in organ transplantation and treatment of autoimmune disease.
Laparoscopic and robotic techniques have both been well adopted as safe options in selected patients undergoing hepatectomy. However, it is unknown whether either approach is superior, especially for ...major hepatectomy such as right hepatectomy or extended right hepatectomy (RH/ERH).
To compare the outcomes of robotic vs laparoscopic RH/ERH.
In this case-control study, propensity score matching analysis was performed to minimize selection bias. Patients undergoing robotic or laparoscopic RH/EHR at 29 international centers from 2008 to 2020 were included.
Robotic vs laparoscopic RH/ERH.
Data on patient demographics, tumor characteristics, and short-term perioperative outcomes were collected and analyzed.
Of 989 individuals who met study criteria, 220 underwent robotic and 769 underwent laparoscopic surgery. The median (IQR) age in the robotic RH/ERH group was 61.00 (51.86-69.00) years and in the laparoscopic RH/ERH group was 62.00 (52.03-70.00) years. Propensity score matching resulted in 220 matched pairs for further analysis. Patients' demographics and tumor characteristics were comparable in the matched cohorts. Robotic RH/ERH was associated with a lower open conversion rate (19 of 220 8.6% vs 39 of 220 17.1%; P = .01) and a shorter postoperative hospital stay (median IQR, 7.0 5.0-10.0 days; mean SD, 9.11 7.52 days vs median IQR, 7.0 5.75-10.0 days; mean SD, 9.94 8.99 days; P = .048). On subset analysis of cases performed between 2015 and 2020 after a center's learning curve (50 cases), robotic RH/ERH was associated with a shorter postoperative hospital stay (median IQR, 6.0 5.0-9.0 days vs 7.0 6.0-9.75 days; P = .04) with a similar conversion rate (12 of 220 7.6% vs 17 of 220 10.8%; P = .46).
Robotic RH/ERH was associated with a lower open conversion rate and shorter postoperative hospital stay compared with laparoscopic RH/ERH. The difference in open conversion rate was associated with a significant decrease for laparoscopic but not robotic RH/ERH after a center had mounted the learning curve. Use of robotic platform may help to overcome the initial challenges of minimally invasive RH/ERH.
Recent findings indicate that mesenchymal stem cells (MSCs) may act as a regulator of Th17 cell differentiation, however, the underlying mechanism is still under debate. To investigate the underlying ...mechanisms of MSCs' regulatory effect, mouse bone marrow–derived MSCs were cocultured with mouse CD4+ CD25low CD44low CD62Lhigh T cells in vitro, and the proportion of induced Th17 cells, cytokines secretion, and transcription factors expression were examined by flow cytometry, enzyme-linked immunosorbent assay, quantitative reverse transcription polymerase chain reaction, and Western blotting. For the first time, our results showed that bone marrow–derived MSCs were able to inhibit Th17 cell differentiation via interleukin (IL)-10 secretion as the Th17 cell proportion was significantly regained when IL-10 was neutralized, or expression of IL-10 by bone marrow–derived MSCs was downregulated by RNA interference technique. Furthermore, IL-10 may suppress expression of Rorγt, the key transcription factor for Th17 cells, both by activating suppressor of cytokine signaling 3 through signal transducers and activators of transcription 5 phosphorylation, and decreasing signal transducers and activators of transcription 3 binding, which is at the promoter of Ror γ t . Thus, our results demonstrate the inhibitory effect of MSCs on Th17 cells differentiation, and suggest increased IL-10 secretion might be the key factor.
Suppression of immune response by mesenchymal stem/stromal cells (MSCs) is well documented. However, their regulatory effects on immune cells, especially regulatory dendritic cells, are not fully ...understood. We have identified a novel Sca-1(+)Lin(-)CD117(-) MSC population isolated from mouse embryonic fibroblasts (MEF) that suppressed lymphocyte proliferation in vitro. Moreover, the Sca-1(+)Lin(-)CD117(-) MEF-MSCs induced hematopoietic stem/progenitor cells to differentiate into novel regulatory dendritic cells (DCs) (Sca-1(+)Lin(-)CD117(-) MEF-MSC-induced DCs) when cocultured in the absence of exogenous cytokines. Small interfering RNA silencing showed that Sca-1(+)Lin(-)CD117(-) MEF-MSCs induced the generation of Sca-1(+)Lin(-)CD117(-) MEF-MSC-induced DCs via IL-10-activated SOCS3, whose expression was regulated by the JAK-STAT pathway. We observed a high degree of H3K4me3 modification mediated by MLL1 and a relatively low degree of H3K27me3 modification regulated by SUZ12 on the promoter of SOCS3 during SOCS3 activation. Importantly, infusion of Sca-1(+)CD117(-)Lin(-) MEF-MSCs suppressed the inflammatory response by increasing DCs with a regulatory phenotype. Thus, our results shed new light on the role of MSCs in modulating regulatory DC production and support the clinical application of MSCs to reduce the inflammatory response in numerous disease states.
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