I am wondering if a (semi) solid substrate/scaffold (could be a hydrogel) is necessary for endothelial cells to sprout out to a VEGF producing source. In other words, it it possible to have vascularization in a culture dish without any specific scaffold?
Hello Hanie Kavand
Angiogenesis is a complex process in which the growth of normal, stable, and functional vessels is critically dependent on the coordinated interplay in space and time of different cell types and growth factors.
Binding of VEGF to ECM is critical for proper vascular morphogenesis. The formation of microenvironmental VEGF gradients in the tissue matrix guides new capillary sprouting. The first endothelial cells activated by VEGF become specialized tip cells, which sense the VEGF gradient by extending thin filopodial processes and migrate toward its source.
Studies have shown that appropriate internal scaffold structure can allow the nutrients to infiltrate and provide pathways for new blood vessel ingrowth. The pore size and interconnections between macropores are porous scaffold structure parameters and are two essential factors for blood vessel growth. Although pore size has a strong impact on vascularization, pore interconnection is more critical.
The spatial localization of angiogenic signals in the extracellular matrix is crucial to ensure the proper assembly and maturation of new vascular structures. So, ECM is necessary for vascularization.
Best.
Thank you Malcolm Nobre for the great reply. So, if I somehow manage to provide the necessities, like the VEGF source with a gradient and an anchoring dock in few hundreds of microns from the Endothelial cells or vessels, it would not be odd to observe vascularization in an ECM and scaffold free condition. Given that we have, for example a tumor aggregate and a vessel in a distance.