An enzyme-responsive electrospun polyester membrane for sustained delivery of polymerized 2-methoxyestradiol to treat peritendinous adhesion

INTRODUCTION: Tendon injuries are frequently accompanied by peritendinous adhesion, leading to restricted joint mobility and functional impairment, while effective preventive strategies remain limited in clinical practice. Although physical barriers or anti-adhesion agents have been independently applied, their combined use may achieve superior outcomes. Electrospun membranes (ENMs) are widely utilized as physical barriers but lack intrinsic antifibrotic activity, besides the efficient delivery strategy and mechanism of the anti-adhesion drug 2-methoxyestradiol (2ME2) remain to be elucidated. OBJECTIVES: This study aimed to develop a lipase-responsive electrospun polycaprolactone (PCL) membrane loaded with polymerized 2ME2 to achieve sustained local release, inhibit fibroblast proliferation and collagen deposition, and prevent peritendinous adhesion while elucidating its molecular mechanism. METHODS: Poly2ME2 was synthesized via esterification and reversible addition-fragmentation chain transfer (RAFT) polymerization and incorporated into electrospun PCL membranes. In vitro, effects of membranes on fibroblast proliferation, adhesion, and enzyme-responsive drug release were evaluated. Mechanistically, single-cell RNA sequencing of human tendon samples and RNA sequencing of rat 208F fibroblasts were integrated to investigate 2ME2-mediated transcriptional regulation. In vivo, poly2ME2 membranes were applied in a rat Achilles tendon repair model, followed by histopathological and biomechanical evaluations at 3 and 6 weeks post-intervention. RESULTS: Poly2ME2 was successfully synthesized and uniformly incorporated into the membranes. It exhibited lipase-responsive sustained release and significantly inhibited fibroblast adhesion and proliferation. Mechanistically, during the tendon injury, HIF-1α and downstream Sonic Hedgehog pathway components (Shh, PTCH1, and Gli1) were upregulated, promoting fibroblast-to-myofibroblast transition and excessive collagen deposition, which were effectively suppressed by poly2ME2 treatment. In vivo, both 3% and 6% poly2ME2 membranes markedly reduced peritendinous adhesion with decreased expression of type III collagen, α-SMA, and Sonic Hedgehog proteins. CONCLUSION: The poly2ME2-loaded electrospun PCL membranes demonstrate enzyme-responsive controlled release and prevent peritendinous adhesion via inhibition of the HIF-1α/Sonic Hedgehog signaling pathway, providing a promising therapeutic biomaterial for the clinical prevention of tendon adhesion.