Development of injectable in situ hydrogels based on hyaluronic acid via Diels-Alder reaction for their antitumor activities studies

The objective of this study was to develop an injectable hydrogel based on furfuryl amine-conjugated hyaluronic acid (FA- conj -HA) and evaluate the in vivo anti-4 T1 tumor activity of doxorubicin-loaded hydrogel (DOX@FA- conj -HA gel ). The cargo-free hydrogel (FA- conj -HA gel ) was fabricated through a Diels-Alder reaction at 37 °C with FA- conj -HA as a gel material and four armed poly(ethylene glycol)2000-maleimide (4-arm-PEG2000-Mal) as a cross-linker. The bio-safety of FA- conj -HA gel were assessed, and the in vivo antitumor activity of DOX@FA- conj -HA gel was also investigated. Many 3D network structures were observed from scanning electron microscope (SEM) photograph, confirming the successful preparation of FA- conj -HA gel . The absence of cytotoxicity from FA- conj -HA gel was proved by the high viability of 4 T1 cells. In vivo bio-safety studies suggested that the obtained FA- conj -HA gel did not induce acute toxicity or other lesions in treated mice, confirming its high bio-safety. The reduced tumor volumes, hematoxylin-eosin staining (H&E), and TdT-mediated dUTP-biotin nick end labeling (TUNEL) analysis indicated the potent in vivo anti-4 T1 tumor effects of DOX@FA- conj -HA gel . In conclusion, the favorable bio-safety and potent antitumor activity of DOX@FA- conj -HA gel highlighted its potential application in oncological therapy.