Human primary co-culture angiogenesis assay reveals additive stimulation and different angiogenic properties of VEGF and HGF

Therapeutic angiogenesis aims to induce blood vessel growth in acute or chronic ischemic tissues and has gained tremendous interest over the last years. To study factors and combinations thereof that potentially induce or modify angiogenesis and to evaluate their therapeutic potential, various in vitro assays have been developed. Although endothelial cells have attracted most attention in these assays, they alone cannot complete vessel maturation since extracellular matrix (ECM) components and mesenchymal cells also play an important role in vascular development. To address this complexity we focussed on a human co-culture angiogenesis assay comprising primary endothelial cells as well as primary ECM-producing fibroblasts. In this assay HGF and VEGF as single factors and combined were tested for the potential to induce an angiogenic response, which was detected by image analysis assessing the area, length and branches of the formed vascular structures. The results show that the cytokines HGF and VEGF both promote angiogenesis in this co-culture assay by inducing distinguishable patterns of vascular structures. VEGF increases the length, area and branch point number of induced vessels whereas HGF mediates exclusively vascular area growth resulting in vascular structures of enlarged diameter. Moreover, the combination of both cytokines results in an additive increase of vascular diameter. (C) 2004 Elsevier Ltd. All rights reserved.