Bcl2-induced vascular maturation

Overexpression of a caspase-resistant form of Bcl-2 (D34A) in human umbilical vein endothelial cells (EC) implanted into immunodeficient mice promotes the maturation of human EC-lined microvessels invested by vascular smooth muscle cells (VSMC) of mouse origin. In contrast, EC implants not overexpressing Bcl-2 form only simple, uncoated EC tubes. Here we compare the phenotypes of vessels formed in vivo and the transcriptomes in vitro of EC expressing different forms of Bcl-2. Wild type Bcl-2, like the caspase resistant D34A Bcl-2 mutant, is anti-apoptotic in vitro and promotes VSMC recruitment in vivo, whereas a G145E mutant that has diminished anti-apoptotic activity in vitro does not promote vessel maturation in vivo. The D34A and wild type forms of Bcl-2, but not the G145E mutant form of Bcl-2 significantly regulate RNA transcripts previously associated with EC-VSMC interactions and VSMC biology, including matrix Gla protein, insulin like growth factor binding protein (IGFBP)-2, matrix metaloproteinase-14 (MMP14), ADAM17 and Stanniocalcin-1. These effects of Bcl-2 on the transcriptome are detected in EC cultured as angiogenic 3-D tubes but are attenuated in EC cultured as 2-D monolayers. Bcl-2-regulated transcription in EC may contribute to vascular maturation, and support design of tissue engineering strategies using EC.

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Enis DR, Dunmore B, Johnson N, Pober JS, Print CG