Aim

Osteoarthritis is a degenerative joint disease characterized by the destruction of joint cartilage. Mesenchymal stem cells (MSCs) are found in low numbers in normal cartilage, mainly in the superficial layer, acting as repairing agents. In OA, MSCs are seen in larger numbers, but act chaotic and are unable to repair the cartilage. The synovial membrane becomes inflamed and interacts with the cartilage. Transplanted MSC have the ability to normalize them, redirecting them to their normal function. In a preliminary study, we showed that MSC could improve knee OA in four patients at 6 months. This report shows their long-term follow-up at 5 years.

Methods

One patient was lost to follow-up at 2 years and three were followed for 5 years. They were aged 55, 57, 65 and 54 years, and had moderate to severe knee osteoarthritis. The worse knee of each patient was injected with 8–9 × 10⁶ MSC.

Results

As previously reported, all parameters improved in transplant knees at 6 months (walking time, stair climbing, gelling pain, patella crepitus, flection contracture and the visual analogue score on pain). Then, they started gradually to deteriorate, but at 5 years they were still better than at baseline. PGA (Patient Global Assessment) improved from baseline to 5 years. The better knee at baseline (no MSC), continued its progression toward aggravation and at 5 years became the worse knee.

Conclusion

Transplant knees were all in a rather advanced stage of OA. Earlier transplantation may give better results in long-term follow-up. This is what future studies have to demonstrate.