Tissue adhesiveness and host response of in situ photopolymerizable interpenetrating networks containing methylprednisolone acetate

Interpenetrating networks (IPNs) of varying formulations were investigated as candidates for an in situ photopolymerizable drug delivery matrix containing poly(ethylene glycol) diacrylate and gelatin. The anti-inflammatory agent methylprednisolone acetate was loaded into the IPN. Bond strength between the IPN and tissue (i.e., muscle, dermis, skin) was determined by a modified American Society for Testing and Materials peel test at constant peel rate. The IPNs provided adhesion values of up to 5.7N, which were three- to fivefold lower than that of the commercial tissue bioadhesive. The subcutaneous cage implant system was utilized to assess material host response and drug efficacy in vivo. IPN formulations elicited a more intense acute inflammatory response than the empty cage controls. Methylprednisolone acetate loaded within the IPNs lowered the level of inflammatory response to levels that were comparable to the empty cage baseline controls. In conclusion, a methodology was developed to quantify the tissue adhesiveness of an in situ photopolymerized IPN matrix containing anti-inflammatory agents. The efficacy of drug-loaded IPN in affecting the host inflammatory response was demonstrated in vivo.