Engineering branching morphogenesis using cell communication

Abstract

Branching morphogenesis, a specialized part of morphogenesis, leads to the formation of microstructures (tubes, canals, and glands), source of the active organ functions. The dynamic mechanisms involved are appearance/disappearance of biomolecules morphogens gradients. In the context of angiogenesis, growth factors allow the initiation, regulation, and remodeling of blood vessels. In the particular case of micro-vascularization, it seems essential to reproduce and study the interaction of endothelial cells with their environment but also with other cellular components, including fibroblasts.

To bring understanding here, we developed an angiogenesis 3D bioprinted (microextrusion bioprinting) model based on a proliferative bioink (7.5% (w/v) gelatin, 0.5% (w/v) alginate, 2% (w/v) fibrinogen) populated with fibroblasts and HUVECs. We demonstrated that we were able to recapitulate branching angiogenesis, producing organized microvascularization tissue in 7 days only.

We clearly demonstrated that a bidirectional communication was at stake between the two cell types, evidenced only when both types were culture in a 3D environment. Proteomic results (multiplexed ELISA) consolidated the understanding of this phenomenon, with 11 angiogenic proteins identified in the co-culture supernatant. They were identified as inducers of vasculogenesis and angiogenesis. Through matrix composition and cell organization study, we were able to demonstrate that tissue remodeling, extracellular matrix production (type I collagen), phenotype modification (pericytes) were taking place in our branching morphogenesis model.

Thanks to this breakthrough scientific advance in the field of regenerative medicine, we can imagine the biofabrication of functional tissues and organs models in the coming decades.