Improved Tendon Radioprotection by Combined Cross-linking and Free Radical Scavenging

Abstract

Allograft safety is a great concern owing to the risk of disease transmission from nonsterile tissues. Radiation sterilization is not used routinely because of deleterious effects on the mechanical integrity and stability of allograft collagen. We previously reported several individual cross-linking or free radical scavenging treatments provided some radioprotective effects for tendons. We therefore asked whether a combination of treatments would provide an improved protective effect after radiation exposure regarding mechanical properties and enzyme resistance. To address this question we treated 90 rabbit Achilles tendons with a combination of cross-linking (1-ethyl-3-[3-dimethyl aminopropyl] carbodiimide [EDC]) and one of three scavenging regimens (mannitol, ascorbate, or riboflavin). Tendons then were exposed to one of three radiation conditions (gamma or electron beam irradiation at 50 kGy or unsterilized). Combination-treated tendons (10 per group) had increases in mechanical properties and higher resistance to collagenase digestion compared with EDC-only and untreated tendons. Irradiated tendons treated with EDC-mannitol, -ascorbate, and -riboflavin combinations had comparable strength to native tendon and had averages of 26%, 39%, and 37% greater, respectively, than those treated with EDC-only. Optimization of a crosslinking protocol and free radical scavenging cocktail is ongoing with the goal of ensuring sterile allografts through irradiation while maintaining their structure and mechanical properties.

Inactivation Effect of Standard and Fractionated Electron Beam Irradiation on Enveloped and Non-Enveloped Viruses in a Tendon Transplant Model

“…Furthermore, the evaluated D 10 values coincide with the results of other studies, which investigated the virus inactivation by gamma irradiation. It confirms the findings from Seto et al [28,40] and Dziedzic-Goclawska et al [31] who proclaimed a comparable impact of Ebeam and gamma irradiation. HIV-2 was the most resistant virus in this study what seems to be contrary to the results of Pruss et al [20] where the investigated parvovirus was the most resistant virus.…”

Gamma Radiation Sterilization Reduces the High-cycle Fatigue Life of Allograft Bone

“…Methods to reduce the effect of irradiation or recover allograft strength therefore remain important to pursue. Irradiated bone allograft can be subjected to free radical scavenger treatment or crosslinking agents to restore some of the strength of the collagen backbone after testing [3,39,58,61,62]. Our study provides an S-N relationship at standard radiation dose, which can be useful in future studies that seek to maintain allograft strength after sterilization.…”

γ-Irradiation sterilized bone strengthened and toughened by ribose pre-treatment

“…Seto et al (2008Seto et al ( , 2009 and Ng et al (2013) demonstrated improved tangent modulus and strength in tendons treated with exogenous collagen crosslinking prior to γ-irradiation sterilization than in conventionally irradiated tendons. Perhaps due to reports suggesting that extra crosslinking in healthy bone leads to embrittlement (Currey et al, 1995;Vashishth et al, 2001;Willett et al, 2013), crosslinking before or during irradiation of bone has not been previously tested.…”