In vitro cytotoxicity of injectable and biodegradable poly(propylene fumarate)-based networks: unreacted macromers, cross-linked networks, and degradation products.

This study evaluates the in vitro biocompatibility of an injectable and biodegradable polymeric network based on poly(propylene fumarate) (PPF) and the cross-linking agent PPF-diacrylate (PPF-DA). Using a methyl tetrazolium (MTT) assay, the effect of the concentrations of PPF and PPF-DA on the cytotoxicity of its unreacted macromers, cross-linked networks, and degradation products was examined. The influence of network structure properties on cell viability and attachment to the cross-linked material was also investigated. The unreacted macromers exhibited a time- and dose-dependent cytotoxic response that increased with more PPF-DA in the mixture. Conversely, the cross-linked networks formed with more PPF-DA did not demonstrate an adverse response because increases in conversion and cross-linking density prevented the extraction of toxic products. Fibroblast attachment was observed on the PPF/PPF-DA networks with the highest double bond conversions. The degradation products, obtained from the complete breakdown of the networks in basic conditions, displayed a dose-dependent cytotoxic response. These results show that there are concerns regarding the biocompatibility of injectable, biodegradable PPF/PPF-DA networks but also sheds light onto potential mechanisms to reduce the cytotoxic effects.