In vivo biocompatibility of poly-N-isopropylacrylamide (PNIPAM) hydrogels in Wistar rats: Hematological, biochemical, and histopathological assessments.

In vitro regeneration of different tissues requires the synthesis of a scaffold material and the compatibility with the desired cell type to achieve a functional unit for transplantation. Poly-N-isopropylacrylamide (PNIPAM) and cationic copolymers hydrogels are effective scaffolds, supporting cell in vitro adhesion and development without cytotoxicity. This study aimed to analyze the in vivo biocompatibility of PNIPAM and PNIPAM co-3 % APTA (3-((acrylamidopropyl) trimethyl-ammonium chloride, APTA)) 3D architecture implanted in female and male Wistar rats. Hydrogel half-discs were implanted in subcutaneous pockets of 3 rats per treatment group (control (without hydrogel), PNIPAM, and PNIPAM co-3 % APTA) for 30 days. The healing process was monitored and after 30 days, the rats were sacrificed following an approved animal care protocol. Blood samples were collected for hematological and biochemical analyses and hydrogels, kidneys, liver, and spleen samples for histopathological evaluation. The results showed no alterations in the healing process in all the animals evaluated. Hematological parameters, liver enzyme activities, nitrogenous waste products and histopathological studies showed no changes across all experimental groups. PNIPAM and PNIPAM co-3 % APTA hydrogels are biocompatible in a female and male murine model over a 30-day period, maintaining stable hematological, biochemical, and histological parameters without alterations.