Reconstituting Angiogenesis in Vitro

Sci. Signal.  30 Apr 2013:
Vol. 6, Issue 273, pp. ec99
DOI: 10.1126/scisignal.2004278

New blood vessels form from existing ones through a process called angiogenesis. Excessive or impaired angiogenesis contribute to various diseases, including cancer and diabetic retinopathy (excessive angiogenesis) or diabetic foot ulcers and impaired wound healing (impaired angiogenesis). Thus, drugs that can influence this morphogenetic process are clinically important; however, the currently available methods to assay the effects of such drugs are limited. Nguyen et al. developed a three-dimensional platform consisting of two cylindrical channels in a collagen matrix. Into one channel, endothelial cells were injected and formed a “parent” vessel through which medium was perfused; into the other channel, various pro- or anti-angiogenic cocktails were perfused, creating a gradient through the intervening matrix. Introduction individually of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), or monocyte chemotactic protein-1 (MCP-1) failed to stimulate invasion of endothelial cells into the matrix, but introduction of sphingosine 1-phosphate (S1P) or the phorbol ester PMA stimulated migration of single cells (S1P) or collective cell migration (PMA). Two different cocktails containing combinations of these factors stimulated angiogenic sprouting that ultimately resulted in an endothelial lining of the factor-delivery channel and microvessels connecting the two channels. The integrity of the connected vessels was confirmed by tracking beads introduced into the vessels. Analysis of the morphological characteristics of the newly sprouting vessels confirmed that they recapitulated in vivo events, such as the formation of filopodia-extending tip cells and polarized stalk cells. Although introduction of either a VEGF inhibitor or an inhibitor of the S1P receptor blocked angiogenesis, examination of the morphological characteristics revealed differential effects on sprouting that depended on the inhibitor and the growth factor cocktail into which the inhibitor was introduced. Thus, this system could be useful in exploring mechanisms that regulate various steps in the angiogenic process and in screening for factors or drugs that alter this complex process.

D.-H. T. Nguyen, S. C. Stapleton, M. T. Yang, S. S. Cha, C. K. Choi, P. A. Galie, C. S. Chen, Biomimetic model to reconstitute angiogenic sprouting morphogenesis in vitro. Proc. Natl. Acad. Sci. U.S.A. 110, 6712–6717 (2013). [Abstract] [Full Text]