Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Tissue Eng Part A. 2010 Sep;16(9):2953-66. doi: 10.1089/ten.tea.2009.0635.
Adipose stromal cells (ASCs) express markers and functional properties of pericytes in vitro and, in combination with endothelial cells (ECs), are able to establish multilayer functional vessels in vivo. However, the factors that coordinate EC-ASC communications to promote migration of these cells toward one another, and their heterotypic assembly into vascular structures are not well defined. To understand the mechanisms of EC-ASC interaction, we developed an in vitro model of coculturing ECs with ASCs in a system containing serum but no additional exogenous cytokines or extracellular matrix (ECM) proteins. We demonstrated that ASCs have a profound potential to stimulate morphogenesis of ECs into branching networks of cord structures. The vascular networks developed in 6 days and were stable for at least 3 weeks. This process was associated with an increase in ECM protein production by ASCs and ECs, alpha-smooth muscle actin expression by ASCs, and increased CD31/platelet endothelial cell adhesion molecule-1 (PECAM-1) surface presentation by ECs. The vascular network formation (VNF) was dependent on matrix metalloproteinase activity and cell communications through vascular endothelial growth factor, hepatocyte growth factor, and platelet-derived growth factor-BB pathways. ASCs exhibited significantly higher potential to stimulate VNF than smooth muscle cells and fibroblasts. Media conditioned by ASCs promoted VNF by ECs cultured on smooth muscle cells and fibroblasts, but could not replace the presence of ASCs in coculture. The presence of ASCs in EC-fibroblast cocultures in a low fraction efficiently stimulated VNF. These findings demonstrate that the vasculogenesis-promoting potential of ASCs depends on interaction with ECs involving contact and likely bi-directional interaction, resulting in modulated secretion of cytokines and ECM proteins.
脂肪基质细胞（ASCs）在体外表达周细胞的标志物和功能特性，并与内皮细胞（ECs）结合，能够在体内建立具有多层功能的血管。然而，协调 EC-ASC 通讯以促进这些细胞向彼此迁移，以及它们异质组装成血管结构的因素尚未得到很好的定义。为了了解 EC-ASC 相互作用的机制，我们开发了一种在含有血清但没有额外的外源性细胞因子或细胞外基质（ECM）蛋白的系统中培养 ECs 和 ASCs 的共培养体外模型。我们证明了 ASCs 具有强大的潜力，可以刺激 ECs 形态发生为分支状的条索结构网络。血管网络在 6 天内形成，并至少稳定 3 周。这个过程与 ASCs 和 ECs 增加 ECM 蛋白的产生、ASCs 表达α-平滑肌肌动蛋白以及 ECs 表面 CD31/血小板内皮细胞黏附分子-1（PECAM-1）表达增加有关。血管网络形成（VNF）依赖于基质金属蛋白酶活性和通过血管内皮生长因子、肝细胞生长因子和血小板衍生生长因子-BB 途径的细胞通讯。与平滑肌细胞和成纤维细胞相比，ASCs 具有更高的刺激 VNF 的潜力。ASCs 条件培养基促进了培养在平滑肌细胞和成纤维细胞上的 ECs 的 VNF，但不能替代共培养中 ASCs 的存在。在低比例的 ASCs 存在下，EC-成纤维细胞共培养中有效地刺激了 VNF。这些发现表明，ASCs 的血管生成促进潜力取决于涉及接触的与 ECs 的相互作用，并且可能是双向相互作用，导致细胞因子和 ECM 蛋白的调节分泌。
