Time-space regulating prodrug hydrogels for prevention of peritendinous adhesion

The bidirectional regulations of antiadhesion and regeneration are crucial for Achilles tendon injuries. However, the precise prevention and treatments of peritendinous adhesions both in time and space are still great challenges. Here, a series of time–space regulating prodrug (tannic acid (TA), epigallocatechin (EGC) and epigallocatechin gallate (EGCG)) hydrogels are designed for the prevention of peritendinous adhesion in Achilles tendon contusion and rupture injuries. In the term of space, the self-healing and deformable hydrogels prepared by crosslinking phenylboric acid (PBA) functionalized polyphosphazene (PZBA) with guar gum (GG) through ROS-responsive phenylborate ester (PBAE) can specifically aggregate to the high ROS sites via the ROS-responsive degradation and recombination of PBAE. Thus, providing support and acting as barriers to inhibit fibroblast proliferation. In the term of time, the prodrug strategy using ROS-responsive PBAE as bridging linker can achieve long-term anti-inflammatory effect over 2 weeks. Furthermore, the degradation time of hydrogels matched the course of peritendinous adhesion, thus achieved bidirectional regulations (decrease the gene expression of TGF-β1, COL-1 and COL-3 to antiadhesion in the early stage but increase them to promote regeneration in the late stage). This study presents a promising approach employing smart prodrug hydrogels with time–space regulating properties for prevention of peritendinous adhesion.