Towards Spatiotemporally Controlled Vascular Network Formation within Engineered Tissues

Spatiotemporally controlled vascular network formation is of great importance for facilitating vascularization within engineered tissues. Therefore, we have designed aptamer-functionalized hydrogels to evaluate their potential for growth factor sequestering, controlled release profiles and study their effect on vascular network formation in a co-culture of human umbilical vein endothelial cells (HUVECs) and mesenchymal stromal cells (MSCs). The aptamer-functionalized hydrogels were prepared via photo-polymerization of gelatin methacryloyl and acrydite modified vascular endothelial growth factor specific aptamers along with irgacure 2959. The physicochemical properties analysis of these aptamer-functionalized hydrogels showed higher aptamer retaining capacity within the acrydite modified hydrogels than the control group for as long as 14 days at 37 °C. Furthermore, the VEGF ELISA results confirmed the triggered VEGF release from the aptamer-functionalized hydrogels in the presence of complementary sequence; thus showing on-demand release. In co-culture conditions, the aptamer-functionalized hydrogels supported cell viability and the formation of vascular networks with HUVECs and MSCs within the hydrogels for up to 8 days. These initial results confirmed the bioactivity of the bound VEGF molecules after their loading within the aptamer functionalized hydrogels; and their ability to control vascular network formation spatiotemporally.