Stimulation of adipogenesis of adult adipose-derived stem cells using substrates that mimic the stiffness of adipose tissue

Biochemical and biomechanical extracellular matrix (ECM) cues have recently been shown to play a role in stimulating stem cell differentiation towards several lineages, though how they combine to induce adipogenesis has been less well studied. The objective of this study was to recapitulate both the ECM composition and mechanical properties of adipose tissue in vitro to stimulate adipogenesis of human adipose-derived stem cells (ASCs) in the absence of exogenous adipogenic growth factors and small molecules. Adipose specific ECM biochemical cues have been previously shown to influence adipogenic differentiation; however, the ability of biomechanical cues to promote adipogenesis has been less defined. Decellularized human lipoaspirate was used to functionalize polyacrylamide gels of varying stiffness to allow the cells to interact with adipose-specific ECM components. Culturing ASCs on gels that mimicked the native stiffness of adipose tissue (2 kPa) significantly upregulated adipogenic markers, in the absence of exogenous adipogenic growth factors and small molecules. As substrate stiffness increased, the cells became more spread, lost their rounded morphology, and failed to upregulate adipogenic markers. Together these data imply that as with other lineages, mechanical cues are capable of regulating adipogenesis in ASCs.     

Interspecies differences with in vitro and in vivo models of vascular tissue engineering

In arterial replacement there is a clear clinical need for a functional substitute possessing appropriate haemocompatible properties to be implanted as small diameter artery. Endothelial cell seeding constitutes an appreciated method to improve blood compatibility on the condition that cells firmly adhere to the support. Along this way, an innovative technique based on multilayered polyelectrolyte films (PEM) as cell adhesive substrate was previously validated in vitro and in vivo in a small-animal model. In this study, we extended the work on a larger animal (sheep) to validate furthermore the paradigm of PEM functionalization for vascular substitutes. We tested in vitro: the efficiency of PEM to induce endothelial progenitor differentiation in sheep endothelial cells; the ability of PEM to sustain cell proliferation and allow resistance to shear stress; the fate of PEM-coated de-endothelialized human saphenous veins under flow conditions, a prerequisite step before in vivo experiments. Despite in vitro differences we were encouraged by testing in vivo PEM-coated prosthesis as carotid replacement in sheep, but without success. In order to explain the implantation failure, an in vitro haemocompatibility evaluation was performed that highlighted interspecies differences able to explain, at least in part, the graft failure obtained.     

Development of an Odontoblast In Vitro Model to Study Dentin Mineralization

The aim of the present work was to characterize the odontoblastic proliferation, differentiation, and matrix mineralization in culture of the recently established M2H4 rat cell line. Proliferation was assessed by cell counts, differentiation by RT-PCR analysis, and mineralization by alizarin red staining, atomic absorption spectrometry, and FTIR microspectroscopy. The results showed that M2H4 cell behavior closely mimics in vivo odontoblast differentiation, with, in particular, temporally regulated expression of DMP-1 and DSPP. Moreover, the mineral phase formed by M2H4 cells was similar to that in dentin from rat incisors. Finally, because in mice, transforming growth factor (TGF)-β1 over-expression in vivo leads to an hypomineralization similar to that observed in dentinogenesis imperfecta type II, effects of TGF-β1 on mineralization in M2H4 cell culture were studied. Treatment with TGF-β1 dramatically reduced mineralization, whereas positive control treatment with bone morphogenetic protein-4 enhanced it, suggesting that M2H4 cell line is a promising tool to explore the mineralization mechanisms in physiopathologic conditions.     

Establishment of Dental Epithelial Cell Line (HAT-7) and the Cell Differentiation Dependent on Notch Signaling Pathway

Rat incisors grow continuously throughout life. Producing a variety of dental epithelial cells is performed by stem cells located in the cervical loop of the incisor apex. To study the mechanisms for cell differentiation, we established a dental epithelial cell line (HAT-7) originating from a cervical loop epithelium of a rat incisor. Immunochemical studies showed that HAT-7 produced the cells expressing amelogenin, ameloblastin, or alkaline phosphatase (ALP). To illustrate a role of Notch signaling in the determinant of the cell fate, we examined expression patterns of Notch1 and Jagged1 in HAT-7 density dependently. At lower cell density, Notch1- or Jagged1-expressing cells were not seen. However, when they were fully confluent, cells began to express Notch1 or Jagged1 strongly. Some ALP-positive cells were almost consistent with Notch1-expressing cells but not Jagged1-expressing cells. These results suggested that the determinant of direction of differentiation was associated with Notch signaling pathway.     

Keratinocyte Differentiation and Proliferation are Regulated by Adhesion to the Three-Dimensional Meshwork Structure of Type IV Collagen

We examined the behavior of human foreskin keratinocytes (HFKs) on reconstituted type IV collagen gel. HFKs survived for several days and the upper layer cells expressed a differentiation marker, involucrin. Apoptosis was induced after involucrin expression while cell proliferation was suppressed. On molecular type IV collagen, integrins shifted from α2β1 to α3β1 during HFK culture. On type IV collagen gel, HFKs initially expressed integrin α2β1, and later expressed integrin α3β1 in the presence of α2β1 did not disappear. Using synthetic peptides, we examined integrin α2-mediated adhesion to type IV collagen gel. Addition of synthetic peptide dose-dependently inhibited cell adhesion both on type IV collagen gel and on molecular type IV collagen. On type IV collagen gel, weaker phosphorylation of focal adhesion kinase, paxillin, and Akt was observed compared with the molecular forms. Based on these observations, we think type IV collagen gel is a novel culture substrate that mimics the physiological environment for HFKs.     

Hax-1对胶质瘤细胞增殖、迁移和侵袭的作用

目的 探讨造血干细胞特异性相关结合蛋白-1（Hax-1）对胶质瘤细胞增殖、迁移和侵袭的影响。方法 选择2018年9月至2019年6月手术切除并得到术后病理证实的胶质瘤组织35例和颅脑损伤内减压术切除的正常脑组织35例,采用qRT-PCR检测Hax-1 mRNA水平;同时检测胶质瘤细胞系（U87、A172、T98及U343）和人星形胶质细胞（NHAs）Hax-1 mRAN水平。使用Lipofectamine 2000法将Hax-1 siRNAs和阴性对照siRNA转染U87细胞构建Hax-1低表达细胞株,将Hax-1高表达质粒和PCDNA3.1空载质粒转染U343细胞构建Hax-1过表达细胞株,使用蛋白印迹法验证转染效果,采用CCK-8法检测细胞增殖,采用Transwell小室实验检测细胞迁移和侵袭,免疫印迹法检测NF-κB信号通路相关蛋白表达水平（NF-κB、CCND1、C-myc、MMP-2、MMP-9）。结果 胶质瘤组织Hax-1 mRNA水平明显高于正常脑组织（P<0.05）;胶质瘤细胞系（U87、A172、T98及U343）Hax-1 mRNA水平明显高于人星形胶质细胞（P<0.05）,其中U87细胞Hax-1 mRNA水平最高,U343细胞最低。U343细胞转染Hax-1过表达质粒后,Hax-1蛋白水平显著增高（P<0.05）,细胞增殖、侵袭、迁移能力均明显增强（P<0.05）,NF-κB p65及IκBα蛋白磷酸化水平以及CCND1、C-Myc、MMP-2、MMP-9蛋白表达水平明显增高（P<0.05）。U87细胞转染Hax-1 siRNA后Hax-1蛋白水平显著降低（P<0.05）,细胞增殖、侵袭、迁移能力均明显降低（P<0.05）,NF-κB p65及IκBα蛋白磷酸化水平以及CCND1、C-Myc、MMP-2、MMP-9蛋白表达水平明显降低（P<0.05）。结论 胶质瘤组织Hax-1呈高表达,明显促进肿瘤细胞增殖、侵袭和迁移,其机制可能与激活NF-κB信号通路有关。     

Separation Methods of T Cells,Natural Killer,and Dendritic Cells from Peripheral Blood of Cancer Patients using Interleukin-2 and Functional Analysis of Natural Killer Cells after Separation

We aimed to induce three different immune cell subsets from a single blood sample from cancer patients to target different biological characters of cancer cells. In the presence of 6000 IU/ml IL-2, natural killer (NK) cells adhere to plastic. By using this ability, we could separate dendritic cells, T cells, and NK cells from peripheral blood mononuclear cells. The cultured NK cells demonstrated higher nonspecific cytotoxicity against tumor cell lines than did the T cells. Furthermore, adherent NK cells demonstrated higher cytotoxicity than nonadherent NK cells, although there was no difference between adherent and nonadherent NK cells in natural cytotoxicity receptors (NKp30, NKp44, NKp46) and NKG2D expression. With these results, we confirmed that we could induce dendritic cell, T cell, and higher cytotoxic NK cells from a single blood draw, and this methodology facilitates to the use of these cells for clinical grade conditions.