Amniotic Membrane Transplant for Articular Cartilage Repair: An Experimental Study in Sheep

Purpose: The aim of the present study was to compare the potential for cartilage repair of fresh amniotic membrane (AM), cryopreserved AM and cryopreserved AM previously cultured with bone marrow mesenchymal stem cells (BM-MSCs) in an in vivo sheep animal model. Methods: A full-thickness cartilage defect was surgically produced in 12 adult sheep, in the bearing region of the lateral femoral condyle. The animals were randomized into 4 groups (n=3): no treatment of the defect (G1); filling with fresh AM (G2); with cryopreserved AM previously cultivated with BM-MSCs (G3); with cryopreserved AM alone (G4). Postoperatively, the full load was possible. At two months, the animals were euthanized. The quality of the new synthesized tissue was evaluated with the macroscopic, by using International Cartilage Repair Society (ICRS) scale, and histological analyses, by using O'Driscoll scale. Results: The control samples showed an ICRS grade III (abnormal); while the samples of Groups 2, 3 and 4 reported a grade II (similar to healthy cartilage). The mean value of O'Driscoll scale in the control group (3.3) was significantly lower compared to the treatment groups (G2: 10.7; G3: 8; G4: 11.3) (P <0.05). No significant differences were found between the experimental groups. Conclusion: AM could be a suitable material for the management of articular cartilage defects. Stem cells within AM demonstrated to be able to differentiate in chondrocytes in vivo. Fresh AM, cryopreserved AM and cryopreserved AM previously cultivated with BM-MSCs showed similar regenerative properties.