Aptamer based spatiotemporally controlled growth factor patterning for tunable local microvascular network formation in engineered tissues

Spatiotemporally controlled growth factor availability is of crucial importance for achieving hierarchically organized vascular network formation within engineering tissues. Even though current growth factor delivery systems can provide sustained release and growth factor delivery on demand, they generally do not facilitate temporal control over the release rates and thus adaptation in accordance with the needs of growing engineered tissue. Additionally, with conventional growth factor loading methods, growth factors are often subjected to organic solvents or harsh conditions, leading to lower bioactivity and denaturation of the proteins. To overcome these limitations, this manuscript reports on the development of VEGF specific 5 acrydite modified aptamer functionalized GelMA hydrogels. The covalently incorporated aptamers can selectively bind to proteins with high affinity and specificity, and can thus sequester the target protein from the surrounding environment. The manuscript shows that this not only provides temporal control over the growth factor release via complementary sequence hybridization, but also enables local control of microvascular network formation in 3D.