Biocompatibility of Biodegradable Poly(ß-Amino Ester) Hydrogels

Growth plate fractures account for nearly 18.5% of fractures affecting an estimated 75,000 US children. The life-lasting consequence of a growth plate fracture includes development of limbs that are crooked or of unequal length. Current approaches to treating these injuries include surgical removal of the bony bar that forms at the site of the fracture and insertion of fat, silicone, bone wax, or bone cement in an attempt to prevent reformation of the bony bar. These “interpositional” materials, however, cannot ensure restoration of the native growth plate, as 43% of young patients experience a recurrence of the bony bar and/or lack of longitudinal growth, requiring numerous surgeries over their lifetime following a growth plate fracture. The goal of this project is to test the biocompatibility of biodegradable poly(â-amino ester) (PBAE) in bone defects. The degradation kinetics and mechanical properties of PBAEs can be controlled by changing their composition, and prior in vitro studies have demonstrated favorable cytotoxicity. PBAEs of differing composition will be inserted into cylindrical holes in the leg bones of rats. After a suitable period of healing, animals will be euthanized and tissues harvested for analysis of residual biomaterial and formation of bone in the defects.