The Use of Human Amniotic Membrane for Cartilage Repair: A Sheep Study

Studies show that human amniotic cells’ pluripotentency can be influenced to produce chondrocytes and osteocytes through adding demineralized bone (DMB). Objective: This study evaluates the human amniotic membrane (HAM) mixed with DMB to fill defects in sheep models. We hypothesized this membrane would fill these defects with hyaline-like cartilage with chondrocytes populating the matrix. Design: Six adult sheep were used in this study. One hindquarter knee of each sheep was utilized to make two cartilage defects: one on the femoral condyle and one in the trochlear grove. Three control sheep had unfilled defects. Three sheep received HAM/DMB from a placenta to fill the defects. The membrane was folded so the cellular layer faced the defect and the joint while demineralized bone was placed between the layers. The membranes were fixed to the femur and to the trochlear grove. At six months, the sheep were sacrificed for evaluation. Results: Of the controls, defects did not fill with hyaline or fibrocartilage. In HAM/DMB sheep, 50% of the defects retained the membrane, consistent with other animal models. Membrane defects were examined histologically by a validated scoring system. A strong correlation of little statistical difference between the test and the normal cartilages was observed. The defects that retained membranes had evidence of diffuse chondrocyte-like cell proliferation of stromal matrix similar to hyaline cartilage. Conclusions: HAM/DMB is a potential source of pluripotent cells that can influence chondrogenesis in defects in sheep models. The implications for application in a human model are promising and warrant further study.

The Use of Hypothermically Stored Amniotic Membrane for Cartilage Repair: A Sheep Study

Objective: To evaluate the use of hypothermically stored human amniotic membrane for cartilage repair in adult sheep. Studies show that human amniotic membrane contains pluripotent mesenchymal stem cells that can be influenced to produce chondrocytes. It is unknown if human amniotic cells can produce hyaline-like cartilage. This study evaluates the use of hypothermically stored amniotic membrane (HSAM) to fill chondral defects in a sheep model. We hypothesized HSAM would fill defects with hyaline-like cartilage with chondrocytes populating the matrix. One sheep was used as a control, and four sheep received amniotic membrane. Two of these sheep were used as a normal control comparison. A 1 cm2 defect was created on the trochlear grove in all specimens. Each membrane was sized and laid over with the stromal layer facing the subchondral bone and covered with Fibrin sealant. The knees were harvested at five months and underwent morphological, histological, and immunohistological evaluation based on the original validated scoring system by O’Driscoll. The control defect didn’t fill in with hyaline cartilage or fibrocartilage. The defects that successfully retained the graft had evidence of diffuse chondrocyte cell proliferation and showed a stromal matrix similar to hyaline cartilage. The graft samples showed a near 100% morphological fill in the HSAM defect contrasting to <10% fill in the control defect. The retained HSAM grafts scored 2.5 on a 0 - 3 cartilage appearance scale compared with 0.5 for the control defects. HSAM is a potential source of pluripotent cells that can influence chondrogenesis in a sheep model. The implications for application in a human model are promising and warrant further study.