Paper BI-TuA10
BioArtificial Matrices to Control Blood Vessel Network Formation

Tuesday, October 16, 2007, 4:40 pm, Room 609

Vascularization of engineered regenerative constructs is a major obstacle in the development of clinically significant regenerative medicine. The ability of regenerative constructs to recapitulate normal blood vessel wiring is central to their successful integration with host tissue, proper physiological function, and long term survival. The natural formation of new blood vessel networks is driven by spatially and temporally controlled presentation of positive and negative cues that direct cell behavior to initiate vessel sprouting, migration, and stabilization.¹ We have developed a strategy for engineering regenerative constructs with spatially patterned biomolecules to direct the formation of orderly networks of blood vessels in artificial biomaterials. Our approach employs a photopatterning technique to convalently link bioactive peptides to poly(ethylene glycol) (PEG) hydrogels to modulate and direct cell function. In this system, peptides are attached to the surface of PEG hydrogel through the use of a photoactive crosslinking agent. Peptides are patterned on the hydrodel by exposing the peptide and crosslinker solution on the surface to UV light through a Mylar photomask. We achieved sharply defined patterns of fluorescently labeled peptide with 10 µm features. We anticipate that the system can easily produce higher resolution patterns. We employed the photopatterning technique to create various patterns of the adhesive ligand RGDS on a nonadhesive PEG background. We have shown that we can constrain the adhesion and morphology of NIH fibroblast cells to the patterned RGDS with this system. We have also used RGDS functionalized PEG hydrogels to induce tubule formation of human aortic endothelial cells, and we have successfully created patterns of labeled RGDS resembling branching microvasculature. We plan to use these patterns to direct the growth of vascular sprouts from explanted sections of mouse aorta into a vascular network. Ultimately we will employ a system to pattern ligands in 3D to direct vascularization of an implanted hydrogel in vivo. The central hypothesis of this work is that spatiotemporal presentation of bioactive cues will result in directed vascularization of engineered hydrogels from the host tissue and that increased vascularization will result in improved healing, integration, and function of regenerative constructs.

¹M. P. Lutolf and J. A. Hubbell, Nature biotechnology 23 (1), 47 (2005).