Abstract: This investigation explores a new cartilage repair technique that uses a novel method to secure a non-woven multifilamentous scaffold in the defect site after microfracture. The hypothesis is that a scaffold provides a larger surface area for attachment and proliferation of the mesenchymal stem cells that migrate from the bone marrow. Two in-vivo studies were undertaken in an ovine model. The first study, which lasted for 8 weeks, aimed to compare the new technique with microfracture. Chondral defects, 7 mm in diameter, were created in both femoral medial condyles of five ewes. One defect was treated with the new technique while the contralateral knee was treated with microfracture alone. The results revealed that the quantity of repair tissue was significantly greater in the defects treated with the new system. The second study had two time points, 3 and 6 months, and used 13 ewes. In this study, both defects were treated with the new technique but one received additional subchondral drilling in order to stimulate extra tissue growth. The majority of the implants had good tissue induction, filling 50-100 per cent of the defect volume, while the compressive modulus of the repairs was in the range of 40-70 per cent of that for the surrounding cartilage. In addition, hyaline-like cartilage was seen in all the repairs which had the additional drilling of the subchondral bone.
Abstract: Ovine bone marrow mesenchymal cells (BMMCs) were seeded on to non-woven filamentous plasma-treated polyester scaffolds and cultured in a chondrogenic medium for 4 weeks. Thereafter a pulsatile hydrostatic pressure (PHP) was applied to these cell-scaffolds constructs at an amplitude of 0.1 MPa and frequency of 0.25 Hz, for 30 min a day, over a period of 10 days. Samples (n = 6) were removed 24 h after PHP stimulation at days 1, 4, 7, and 10 for biochemical analysis. Similar analyses were conducted, at the same time points, on control samples that were not subjected to a PHP. The results showed that the glycosaminoglycan (GAG) content did not significantly increase until after the application of a PHP for 7 days. The GAG content was 1.5 and 2.7 times higher in the PHP group than in the control group at days 7 and 10 respectively (p<0.01). The deoxyribonucleic acid (DNA) content was 1.5 times greater in the PHP group than in the control group at day 10 (p<0.01). GAG synthesis amounts, expressed as the total GAG contents per microgram of DNA, were 1.6 and 1.8 times higher in the PHP group than in the control group at days 7 and 10 respectively (p<0.01). The total collagen content in the medium did not change until after PHP application for 10 days, when it was 1.9 times higher than the control (p < 0.05). The results suggest that a light PHP applied at a low frequency has a cumulative stimulatory effect on the BMMCs' metabolic activities including cell proliferation and synthesis of the extracellular matrix.
