Berthod François, Germain Lucie, Tremblay Nathalie, Auger François A
Laboratoire d'Organogénèse Expérimentale (LOEX), Centre hospitalier affilié universitaire de Québec, Hôpital du Saint-Sacrement, Québec, Canada.
J Cell Physiol. 2006 May;207(2):491-8. doi: 10.1002/jcp.20584.
The contribution of the cellular and fibrillar microenvironment to angiogenesis still remains unclear. Our purpose was to evaluate the effect of the extracellular matrix deposited by fibroblasts on the capacity of human endothelial cells to form capillaries in vitro. We have drastically decreased the amount of extracellular matrix surrounding fibroblasts in our model of endothelialized-reconstructed connective tissue (ERCT) by culturing it without ascorbate. Under these conditions, the number of capillary-like tubes (CLT) formed by endothelial cells was reduced by up to 10-fold after 31 days of culture compared to controls. This decrease was due neither to a variation of MMP-2 and MMP-9 secretion, nor to a reduction in the number of fibroblasts and/or endothelial cells, or a diminution of fibroblast growth factor 2 (FGF2) synthesis. The secretion of vascular endothelial growth factor (VEGF) by fibroblasts accounted for 25-70% of the capillary-like tube formation when tissues were cultured in the presence or absence of ascorbate, as demonstrated by VEGF-blocking studies. The culture of endothelial cells on a similar extracellular matrix but in the absence of living fibroblasts did not promote the formation of CLT, even when tissues were fed with fibroblast-conditioned medium. Thus, the deposition of a rich extracellular matrix by living fibroblasts appeared necessary, but not sufficient to promote capillary-like formation. Fibroblasts seem to induce endothelial cells to spontaneously form CLT by secreting and organizing an abundant extracellular matrix, which creates a microenvironment around cells that could in turn trap growth factors produced by fibroblasts and promote three-dimensional cell organization.
细胞和纤维状微环境对血管生成的贡献仍不清楚。我们的目的是评估成纤维细胞沉积的细胞外基质对人内皮细胞体外形成毛细血管能力的影响。在我们的内皮化重建结缔组织（ERCT）模型中，通过在无抗坏血酸的条件下培养，我们大幅减少了成纤维细胞周围细胞外基质的量。在这些条件下，与对照组相比，培养31天后内皮细胞形成的毛细血管样管（CLT）数量减少了多达10倍。这种减少既不是由于MMP-2和MMP-9分泌的变化，也不是由于成纤维细胞和/或内皮细胞数量的减少，或成纤维细胞生长因子2（FGF2）合成的减少。VEGF阻断研究表明，无论组织在有无抗坏血酸的情况下培养，成纤维细胞分泌的血管内皮生长因子（VEGF）占毛细血管样管形成的25%-70%。在内皮细胞于类似细胞外基质上培养但无活成纤维细胞的情况下，即使给组织添加成纤维细胞条件培养基，也不会促进CLT的形成。因此，活成纤维细胞沉积丰富的细胞外基质似乎是必要的，但不足以促进毛细血管样的形成。成纤维细胞似乎通过分泌和组织丰富的细胞外基质来诱导内皮细胞自发形成CLT，这在细胞周围创造了一个微环境，进而可以捕获成纤维细胞产生的生长因子并促进三维细胞组织的形成。
