Non-destructive in vivo tracking of gelatin hydrogels for advancing tissue engineering

Photo-crosslinkable gelatin-based hydrogels hold great promise for tissue engineering and regenerative medicine. However, monitoring these hydrogels in vivo remains challenging and limits their further development and clinical translation. Here, we address this limitation by utilizing a gelatin-based hydrogel that incorporates the radiopaque compound 5-acrylamido-2,4,6-triiodoisophthalic acid (AATIPA). In an in vivo study spanning over 400 days, we monitor the degradation kinetics of these hydrogels using computed tomography and ultrasonography. We synthesize three distinct AATIPA-containing hydrogels and implant them subcutaneously into mice. Hydrogels with high crosslink density show minimal degradation, while those with lower crosslinking densities degrade within approximately three months. Histological evaluation reveals that the scaffolds are replaced by adjacent adipose tissue. In vitro, adipose-derived stem cells differentiate into the adipogenic lineage, corroborating the in vivo findings. These results highlight the potential of these hydrogels for adipose tissue engineering by enabling in vivo monitoring and offering tailored degradation profiles. (Figure presented.)