Tropoelastin coated PLLA-PLGA scaffolds promote vascular network formation

The robust repair of large wounds and tissue defects relies on blood flow. This vascularization is the major challenge faced by tissue engineering on the path to forming viable thick, implantable tissue constructs. Without the presence of this vascular network, oxygen and nutrients cannot reach the cells located far from host blood vessels. To create viable constructs, tissue engineering takes advantage of the mechanical properties of synthetic materials, while combining them with extracellular matrix (ECM) proteins to create a natural environment for the tissue-specific cells. Tropoelastin, the precursor of the elastin, is the ECM protein responsible for elasticity in all elastic tissues in the body, including robust blood vessels. We seeded human adipose microvascular endothelial cells (HAMECs) combined with mesenchymal stem cells (MSCs) on poly(L-lactic acid)/poly(lactide-co-glycolide) (PLLA/PLGA) scaffolds treated with tropoelastin, and examined the morphology, expansion and maturity of the newly formed vessels. Our in vitro results demonstrate that the treated scaffolds show a more expanded, complex and developed vascularization, in comparison to the untreated control group. To further explore the benefits of tropoelastin-treated scaffolds, we implanted pre-vascularized constructs within the mouse abdominal wall muscle by replacing a piece of the muscle with the engineered constructs. Within 12 days after implantation, we saw enhanced perfusion by host blood vessels. These results point to the great potential of these combined materials in promoting the vascularization of implanted tissue engineered constructs