Friday, October 21, 2011: 10:20 AM
101 I (Minneapolis Convention Center)
The lack of vascularization in implanted tissue engineered constructs has been one of the principal challenges of tissue engineering. Cells residing at a critical distance (>100 microns) from the blood supply on an implanted scaffold are limited by diffusion, nutrient delivery and waste removal. In this study, we present scaffolds composed of a pH-sensitive polymer, dimethylaminoethyl methacrylate (DMAEMA) and biocompatible polymer, 2-hydroxyethyl methacrylate (HEMA). Our pH-sensitive scaffolds increase their pore size when exposed to low pH, thereby allowing an increase in flux. In vitro pO2 measurements and cell viability studies confirm higher oxygen levels and cell proliferation in DMAEMA/HEMA scaffolds compared to nonresponsive HEMA scaffolds. We conducted in vivo studies which corroborated increased cell viability in pH-responsive scaffolds. Immunofluorescence staining of human umbilical vein endothelial cells (HUVECs) seeded in scaffolds after implantation in mice showed that the pH-sensitive DMAEMA/HEMA (30/70, mol/mol) scaffolds provided an environment more favorable to cell survival, as a significant number of cells were present after implantation compared to HEMA scaffolds. Additionally, DMAEMA/HEMA (30/70, mol/mol) scaffolds exhibited vessel formation while cells seeded onto HEMA scaffolds did not. We present a scaffold design that significantly increases cell survival by increasing oxygen availability through a self-actuating, pH-responsive mechanism.