Abstract
Background
Based on decellularisation and cleaning processes of trabecular bone and fibrocartilage, an osteochondral allograft has been developed.
Material
The chemical process, established thanks to bone and fibrocartilage data, included an efficient viroinactivation step. The raw material was a tibial plateau collected during knee arthroplasty, cut in cylinders strictly selected (>2mm cartilage height and total height between 10 and 16mm). The grafts were freeze-dried and gamma sterilised.
Methods
Decellularisation and structure integrity were validated based on histological analysis, before and after treatment. Mesenchymal Stem Cells (MSC) proliferation in contact with the graft was evaluated to validate the biocompatibility. Biomechanics of the cartilage was studied to determine the compressive resistance before and after treatment. Proof of concept has been completed on femoral condyles in a rabbit model: osteochondral allografts of rabbit were prepared from femoral condyles, processed like human allografts and implanted in 6 femoral condyle defects of 4mm diameter and compared to 3 sham-operated sites. Rabbits were sacrificed at 12 weeks. Macroscopic evaluation and histological stainings were carried out to determine bone and cartilage reconstruction.
Results
The stainings of processed grafts showed decellularisation, cleaning of bone, porosity of cartilage tissue, decrease in the aggrecan rate and preservation of type II collagen. MSC proliferated inside the trabecular bone and spread at the surface of the cartilage tissue after 3 weeks. Compressive resistance of cartilage before and after processing was similar to literature. Osteochondral rabbit defects were filled with bone and cartilage tissue, with total integration of bone and cartilage repair observed in two ways: cells spreading from lateral cartilage and MSC diffusing from subchondral plate.
Conclusions
The decellularised biocompatible osteochondral allograft enhanced cartilage repair in an animal model. Two clinical trials are ongoing in talus and knee osteochondral lesions.
