[Gene expression profiling of microvascular endothelial cells during capillary morphogenesis in an in vitro model of angiogenesis]

Abstract

Objective: To globally compare the gene expression profiles during the capillary morphogenesis of human microvascular endothelial cells (HMVECs) in an in vitro angiogenesis system with Affymetrix oligonucleotide array.

Methods: A microcarrier-based in vitro angiogenesis system was developed, in which endothelial cells (ECs) migrated into the matrix, proliferated, and formed capillary sprouts. The sprouts elongated, branched and formed network. The total RNA samples from the HMVECs at the selected time points (0.5 h, 24 h, and 72 h) during the capillary morphogenesis were used for microarray analyses, and the data were processed with the software provided by the manufactory. The expression patterns of some genes were validated and confirmed by Semi-quantitative RT-PCR. The regulated genes were grouped based on their molecular functions and expression patterns, and among them the expression of chemokines/chemokine receptors were specially examined and their functional implications were analyzed.

Results: About 1500 genes were found up- or down- regulated 2-folds or above detected by the arrays, and among them, about 400 genes regulated 3-folds or above. The regulated genes could be grouped into categories based on their molecular functions such as growth factor and receptor, cell proliferation, extracellular matrix, cell cycle and apoptosis, signaling molecule and transcription factor, and so on, using the Gene Ontology Mining Tool in The NetAffx Analysis Center. The regulated genes were also clustered into six groups based on their patterns of expression. As for chemokines, the CCL2/MCP-1, CCL5/RANTES and CX3CL1 were identified to be specially upregulated at 24 h time point when the sprouting characterized the morphological change. It was thus suggested that they might exert crucial roles at the early stage of angiogenesis.

Conclusions: Based on our angiogenesis model, and by oligonucleotide arrays, the present study demonstrates global profiles of the gene expression during endothelial capillary morphogenesis, and the results provide us much information about the molecular mechanisms of angiogenesis, with which further evaluation of individual genes can be encouraged.