Enhancement Of Meniscus Repair In The Avascular Zone Using Mesenchymal Stem Cells In A Porcine Model
Dutton.A, Hui.J, Goh.J, Lee.E.H
Introduction
Loss of the meniscus leads to abnormal load transmission across the knee joint. Thus there is a current move toward meniscus preservation. Traditionally, meniscal tears in the avascular zone have been treated with partial meniscectomy due to poor repair potential. Our study investigates the use of mesenchymal stem cells to enhance the repair of meniscal tears in the avascular zone in a porcine model.
Methods
The vascular supply of the porcine meniscus was defined using microangiography barium sulphate. This was compared to the human vascular pattern. 26 adult pigs (52 knees) underwent meniscal procedures. Autologous adult mesenchymal stem cells were harvested from the iliac bone of each pig. Then the control group 1 had a meniscal radial tear created and left untreated. Control group 2 had the meniscal tear repaired with suture and fibrin glue. The experimental group had the tear treated with mesenchymal stem cells, suture and fibrin glue. At 8 weeks the menisci were harvested. The tear was examined grossly and histologically under light microscopy. The repair strength was also biomechanically tested with the Instron machine. The mesenchymal stem cells were labeled with green fluorescent protein and examined with the confocal microscope.
Results
The pattern of vascular supply of the porcine meniscus was confirmed to be similar to that seen in humans. Gross examination of control group 1 revealed no healing in all specimens. Control group 2 had 5 incomplete healing and 11 specimens with no healing. The experimental group had 19 specimens which showed complete healing, 5 specimens incomplete healing and 1 specimen with no healing. Histological examination of the experimental group revealed healing with fibrocartilage-like tissue. The experimental group also had a stronger biomechanical repair. Confocal microscope examination demonstrated the presence of introduced mesenchymal stem cells within the repair which was seen with green fluorescence.
Conclusions
Repair of meniscal tears in the avascular zone has been shown to be improved with mesenchymal stem cells in the porcine model. If these results can be reproduced in clinical trials, then meniscus preservation would be achieved. This would maintain normal knee joint biomechanics and possibly retard the development of osteoarthrosis.