64 Controlled Angiogenesis in the Heart

Abstract

Purpose VEGF can induce normal or aberrant angiogenesis depending exclusively on the amount secreted in the microenvironment, and not on its total dose, as it remains localized in the matrix around each producing cell. To make this concept clinically applicable we developed a FACS-based technique to rapidly purify transduced progenitors specifically expressing a desired VEGF level from a heterogeneous primary population. This project aims at inducing safe angiogenesis by cell-based delivery of controlled VEGF levels. Methods and Materials Human adipose-tissue stem cells (ASC) were transduced with retroviral vectors expressing either rat VEGF linked to a truncated form of rat CD8, or CD8 alone as control. VEGF-expressing cells secreted uncontrolled heterogeneous levels (ALL). From these, a population producing a specific VEGF level (SPEC) was FACS-purified. 15 nude rats underwent direct intramyocardial injection of 10x10 6 cells. Histology was performed after 4 weeks. Results Freshly isolated ASC were transduced with >80% efficiency and FACS-purified at the first passage, minimizing in vitro expansion. SPEC cells produced a similar total VEGF amount (100±37 ng/10 6 cells/day) as the heterogeneous ALL cells (111±25). However every cell in the SPEC population expressed a similar level. Mortality was 6.7%. Cell engraftment was confirmed by immunostaining for the CD8 marker. Both VEGF-producing groups increased vascular density by 2-3 fold. However ALL cells caused the development of numerous aberrant structures, while SPEC cells generated only normal and stable angiogenesis. Download high-res image (44KB) Download full-size image Conclusions Controlled VEGF delivery by FACS-purified ASC is effective to prevent aberrant vascular growth in the myocardium and is a promising novel strategy to achieve safe and therapeutic angiogenesis to treat cardiac ischemia.