干细胞

In the bone marrow microenvironment, endothelial cells (ECs) play a pivotal role in regulating the production of both growth and inhibiting factors. They are held together by adherence molecules that interact with hematopoietic progenitor cells. The study of ECs in the hematopoietic stem cell niche is limited due to the lack of efficient protocols for isolation. In this protocol, we developed a two-step approach to extract bone marrow endothelial cells (BMECs) to unlock the challenges researchers face in understanding the function of the endothelial vascular niche in in-vitro studies.

Induced pluripotent stem cell derived cardiovascular progenitor cells (iPSC-CVPCs) provide an unprecedented platform for examining the molecular underpinnings of cardiac development and disease etiology, but also have great potential to play pivotal roles in the future of regenerative medicine and pharmacogenomic studies. Biobanks like iPSCORE ( Stacey et al., 2013; Panopoulos et al., 2017), which contain iPSCs generated from hundreds of genetically and ethnically diverse individuals, are an invaluable resource for conducting these studies. Here, we present an optimized, cost-effective and highly standardized protocol for large-scale derivation of human iPSC-CVPCs using small molecules and purification using metabolic selection. We have successfully applied this protocol to derive iPSC-CVPCs from 154 different iPSCORE iPSC lines obtaining large quantities of highly pure cardiac cells. An important component of our protocol is Cell confluency estimates (ccEstimate), an automated methodology for estimating the time when an iPSC monolayer will reach 80% confluency, which is optimal for initiating iPSC-CVPC derivation, and enables the protocol to be readily used across iPSC lines with different growth rates. Moreover, we showed that cellular heterogeneity across iPSC-CVPCs is due to varying proportions of two distinct cardiac cell types: cardiomyocytes (CMs) and epicardium-derived cells (EPDCs), both of which have been shown to have a critical function in heart regeneration. This protocol eliminates the need of iPSC line-to-line optimization and can be easily adapted and scaled to high-throughput studies or to generate large quantities of cells suitable for regenerative medicine applications.

The discovery of endothelial colony forming cells (ECFCs) with robust self-renewal and de novo vessel formation potentials suggests that ECFCs can be an excellent cell source for cardiovascular diseases treatment through improving neovascularization in the ischemic tissues. However, their engraftment after transplantation resulted to be low. Previous studies showed mesenchymal stem/stromal cells (MSCs) could improve the survival and capillary formation capacity of ECFCs in co-culture systems. In this article, we describe a protocol for in vitro co-culture of MSCs and ECFCs to prime ECFCs for better engraftment.

Angiogenesis defines the process of formation of new vascular structures form existing blood vessels, involved during development, repair processes like wound healing but also linked to pathological changes. During angiogenic processes, endothelial cells build a vascular network and recruit perivascular cells to form mature, stable vessels. Endothelial cells and perivascular cells secret and assemble a vascular basement membrane and interact via close cell-cell contacts. To mimic these processes in vitro we have developed a versatile three-dimensional culture system where perivascular cells (PVC) are co-cultured with human umbilical cord vascular endothelial cells (HUVEC) in a collagen type I gel. This co-culture system can be used to determine biochemical and cellular processes during neoangiogenic events with a wide range of analyses options.

Cell-cell adhesion ensures tight contacts between neighbouring cells, which is necessary for cell segregation, as well as for the morphological and functional differentiation of different tissues. Evidently there are cell-cell recognition systems that make cells of the same type preferentially adherent to one another. Homotypic cell adhesion is particularly important in mediating a range of physiological processes such as cell survival, migration and remodeling of vessels. Thus in the present study we selected two populations of endothelial progenitor cells which are from the same donor to investigate the possible effect of a small molecule compound Icariin on homotypic cell adhesion. Many angiogenic factors can destabilize the organization of intercellular junctions, causing endothelial barrier opening. In the present study, we observed that Icariin treatment reduced the level of VE-cadherin expression in EPCs indicating a decrease in cell-cell adhesion-a proof of the pro-angiogenic effect of Icariin. In summary, the observed loss of homotypic adhesion of EPCs may contribute to the enhanced angiogenic effect exerted by Icariin.