Our results demonstrated that the novel solution maintained higher chondrocyte viability, the contents and structure of the cartilage matrix, and the biomechanical properties of the allografts compared with vitrification in vitro and in vivo.
An osteochondral allograft (OCA) is currently limited to use within 28–35 days after storage in solution. Vitreous preservation of OCAs can maintain high chondrocyte viability for up to 3 months. However, a comparison of the long-term preservation and transplantation outcomes of storage in solution with those of vitrification has not been carried out.
To determine the effect of Xmu (X Medical University) solution versus vitrification on chondrocyte viability, and the histological and biomechanical properties of OCAs in vivo and in vitro after long-term storage.
The preservation and transplantation outcomes of Xmu solution storage are better than those of vitrification.
Study Design: Controlled laboratory study.
OCAs from femoral condyles of adult New Zealand rabbits were harvested within 2 h of death and stored for 35 days in Xmu solution or by vitrification. Stored OCAs were transplanted into eight recipient rabbits. The storage effect on OCAs and repair outcomes were analyzed at 6 months. Chondrocyte viability as well as proteoglycan (PG) and collagen II contents were assessed in vitro and in vivo. Joint range of motion (ROM), biomechanical properties, and interleukin (IL)-6 content were tested at each timepoint. Fresh OCAs served as controls. Negative and Sham groups were included in experiments in vivo.
Compared with fresh grafts, the results showed significant decreases in chondrocyte viability, and PG and collagen II contents of OCAs after storage and implantation. Storage in Xmu solution maintained chondrocyte viability and cartilage matrix at significantly higher levels than vitrification in vitro and in vivo. In terms of ROM and Young’s modulus in vivo, the Xmu group was better than the vitrification group, but IL-6 content was 381.50±23.70 ng/L in the Xmu group, which was significantly decreased compared with 470.59±38.71 ng/L in the vitrification group after implantation at 6 months.
The Xmu solution maintains higher chondrocyte viability and an intact cartilage matrix architecture of OCAs and improves outcomes after storage and implantation compared with vitrification. However, vitrification reduces the immune response.
Clinical Relevance: Storage in Xmu solution increases the window of opportunity for implantation of optimal tissue up to 35 days after disease testing clearance. Xmu solution also has better preservation effects than vitrification.
Keywords: osteochondral allografts; tissue preservation; implantation; chondrocyte viability