Difference between revisions of "Part:BBa K782061"

Revision as of 19:17, 24 September 2012

VEGF-p2a-PDGF

Introduction

Experimental data show the important regenerating role of vascular endothelial growth factor (VEGF) after acute myocardial infarction (Banfi et al., 2012; Zhang et al., 2008). After binding to its receptor VEGFR1 and VEGFR2 it supports angiogenesis, inhibits endothelial cell apoptosis, promotes endothelial cell proliferation, and restores heart function. Although therapeutic angiogenesis by delivery of vascular growth factors is an attractive strategy, many clinical trials have thus far failed to show efficacy. One of the most likely explanations for this discrepancy is that VEGF induces growth of dysfunctional vessels, if expressed outside of a narrow dosage window (Banfi et al., 2012). Banfi et al. confirmed the hypothesis that co-delivery of platelet-derived growth factor-BB (PDGF-BB), which recruits pericytes, induced normal angiogenesis in skeletal muscle irrespective of VEGF levels. It was also shown that coexpression of VEGF and PDGF-BB encoded by separate vectors in different cells or in the same cells only partially corrected aberrant angiogenesis. In marked contrast, coexpression of both factors in every cell at a fixed relative level via a single bicistronic vector led to robust, uniformly normal angiogenesis, even when VEGF expression was high and heterogeneous. Secondly, a challenge has been that with the conventional gene transfer vectors, the growth factor concentration in target tissues had not reached sufficient levels or had not persisted long enough for triggering relevant vascular growth (Zhang et al., 2008). Cell transplantation strategies emerged as a promising approach to overcome this issue. Zhang et al. reported the first transplantation of microencapsulated engineered xenogeneic CHO cells in post-infarction myocardium, which showed that the supplementation of VEGF from implanted xenogeneic cells could foster the formation of arterial collaterals, improve myocardial perfusion and thus also promote the regeneration of damaged myocardium augmented angiogenesis and improved heart function (Zhang et al., 2008).

Figure 1. Shematic representation of VEGF and PDGF linked with p2A.

• VEGF was obtained from Sino Biological Inc.

Refrences

Banfi, A., von Degenfeld, G., Gianni-Barrera, R., Reginato, S., Merchant, M.J., McDonald, D.M., and Blau, H.M. (2012) Therapeutic angiogenesis due to balanced single-vector delivery of VEGF and PDGF-BB. FASEB J. 26, 2486-2497.

Zhang, H., Zhu, S.J., Wang, W., Wei, Y.J., and Hu, S.S. (2008) Transplantation of microencapsulated genetically modified xenogeneic cells augments angiogenesis and improves heart function. Gene Ther. 15, 40-48.

Sequence and Features