Title:
Vascular morphogenesis of human umbilical vein endothelial cells on cell-derived macromolecular matrix microenvironment.

Abstract:
Extracellular matrix (ECM) is a highly organized network of proteins and other macromolecules that plays a critical role in cell adhesion, migration, and differentiation. In this study, we hypothesize that ECM derived from in-vitro-cultured cells possesses unique surface texture, topography, and mechanical property, and consequently carries some distinct cues for vascular morphogenesis of human umbilical vein endothelial cells (ECs). Cell-derived matrix (CDM) was obtained by culturing fibroblasts, preosteoblasts, and chondrocytes, respectively, on coverslips and then by decellularizing them using detergents and enzymes. These matrices were named fibroblast-derived matrix (FDM), preosteoblast-derived matrix (PDM), and chondrocyte-derived matrix (CHDM). Immunofluorescence of each CDM shows that some of the matrix components are fibronectin (FN), type I collagen, and laminin. Atomic force microscopy analysis presented that average fiber diameter ranged from 2 to 7 μm and FDM holds much larger fibers. The matrix elasticity measurements revealed that average Young's modulus of CHDM (17.7 ± 4.2 kPa) was much greater than that of PDM (10.5 ± 1.1 kPa) or FDM (5.7 ± 0.5 kPa). During 5-day culture, EC morphologies were dramatically changed on PDM and FDM, but those on CHDM and gelatin were rather stable, regardless of time lapse. Cell migration assay discovered quicker repopulation of the scratched areas on PDM and FDM than on gelatin and CHDM. A capillary-like structure (CLS) assembly was also notable only in the PDM and FDM, as compared with CHDM, gelatin, or FN that were very poor in CLS formation. Quantitative analysis of mean CLS branch points and branch lengths demonstrated much better angiogenic activity of ECs on PDM and FDM. Interestingly, CLS formation was closely associated with matrix remodeling by ECs and the matrix clearance on PDM with time was sharply contrasted with that on CHDM that majority of the matrix FN was reserved. It was notable that membrane type 1-matrix metalloprotease was deeply involved in the process of matrix remodeling. This study indicates that specific matrix microenvironments are very critical for vascular morphogenesis of ECs, and thus, provide a nice platform for angiogenesis study as well as vascular tissue engineering.