Evaluation of a novel 4-day decellularisation protocol for porcine flexor tendons: A comparative study with a 26-day process

Rupture of the anterior cruciate ligament is a common sports-related injury that lacks intrinsic healing capacity, often necessitating surgical intervention. Our group has developed a new graft biomaterial, the decellularised porcine super flexor tendon (pSFT), designed to mitigate immune rejection post-implantation by removing cellular components. The current 26-day decellularisation process attenuates the mechanical properties of the graft, potentially disrupting the structural micro-cues that influence cell repopulation and integration. This study investigates a shortened 4-day protocol to determine whether mechanical properties are preserved more closely to native, unprocessed tissue. Histological analysis and DNA quantification confirmed effective cell removal for both the 26-day and 4-day protocols. Native, 26-day processed, and 4-day processed grafts were mechanically evaluated through stress relaxation and failure testing. Following stress relaxation testing, several Maxwell-Weichert viscoelastic parameters were found to significantly differ between 26-day and native groups (E₀, E₁, E₂ & τ₂), whereas between 4-day and native groups fewer significant differences were found (E₁ & E₂). Following failure testing, again several parameters were found to significantly differ between 26-day and native groups (P_FAIL, UTS, E_linear and ε_T), whereas between 4-day and native groups only one parameter was significantly different (E_linear). These findings indicate that the 4-day decellularisation process better preserves the native tissue mechanical properties, potentially reducing structural alterations and improving suitability for anterior cruciate ligament replacement.