(701b) Self-Assembling Biomimetic Hydrogels with Bioadhesive Properties for Tissue Engineering Applications

Tissue engineering is a multidisciplinary field that aims to repair or regenerate lost or damaged tissues and organs in the body. One such area with significant medical applications is the degeneration of the intervertebral disc (IVD), however there is a need for bioadhesive scaffolds for repair of the IVD.  The objective of this work is to generate a bioadhesive polymer that, in addition to bonding with tissue, can support cell survival post‐adhesion.  Thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) was grafted with chondroitin sulfate (CS) (PNIPAAm-g-CS) and blended with aldehyde-modified CS to achieve covalent adhesion upon contact with tissue.  Extracellular matrix (ECM) loaded lipid vesicles (liposomes) were incorporated into the copolymer for enhanced cellular biocompatibility.  The bioadhesive strength was evaluated in contact with porcine ear cartilage. The variables studied included the concentration of CS aldehyde, the oxidation level of CS aldehyde, and the concentration of liposome suspension added. PNIPAAm-g-CS concentration was held constant in all solutions at 5%, as optimized in previous studies. Blends of PNIPAAm-g-CS and varying amounts of CS aldehyde (1-5% w/v) were prepared in phosphate buffered saline (PBS) alone or in a suspension of liposomes and PBS. Incorporating CS aldehyde into the polymer increased the adhesive strength and work of adhesion compared to PNIPAAm-g-CS polymer alone. The sample showing maximum adhesive properties was comprised of 3% CS aldehyde and no liposome solution having a maximum adhesive strength of 2.097 kPa and maximum work of adhesion of 7.736 x 10^-10 J. For each concentration of CS aldehyde, varying the oxidation level produced no significant differences.  As lipid concentration increased there were decreasing trends in both maximum work and adhesive strength. Future work will investigate further optimizing the bioadhesive to maximize its strength and analyzing samples for biocompatibility with human embryonic kidney cells (HEK) and adipose derived stem cells (ASCs).