Pilot Study: Augmentation of ACL Reconstruction With Bone Marrow Stem Cells and Amnion Collagen Matrix Wrap

Histologic studies have determined that graft ligamentization following anterior cruciate ligament (ACL) reconstruction may take from 6 to 18 months. (1) It has been reported that incomplete graft maturation and incorporation is one cause of clinical graft failure. Animal studies have illustrated improved tendon healing/integration in ACL models augmented with stem cell technologies. (2-4). Basic scientists theorize that optimization of stem cell treatments for tissue regeneration requires that a "regenerative triad" be employed, i.e., use of a scaffold, stem cells and growth factors. In the intra-articular environment, research has shown that a scaffold such as an amnion wrap is necessary to contain the stem cells and growth factors in close proximity to the ACL graft. (2, 4, 5)

The normal, uninjured human ACL is covered by a layer of synovial tissue which contributes to the blood supply and nutrition of the native ACL. It is theorized that the lack of a synovial lining after injury and following traditional ACL reconstruction contributes to slow ligamentization and possible failure of reconstructed grafts.(5) Two studies have demonstrated accelerated maturation and ligamentization of human ACL graft augmented with point of care blood products. (6, 7) In one, leucocyte poor platelet rich plasma was injected directly into the body of the graft. (6) In the other, the platelet derived growth factors were loaded in a gelatin carrier which was wrapped around the graft. (7) In both studies accelerated and increased ligament maturation was documented compared to the controls. Collagen membranes derived from amniotic tissue have been successful to aid healing when used in difficult wounds and meniscal repair surgery. (8, 9)

The use of a collagen based -membrane derived from amniotic tissue may be used to help reestablish the natural synovial lining of the reconstructed ACL, in effect acting as both a barrier from the synovial fluid and as a scaffold to contain autologous mesenchymal stem cells and growth factors contiguous with the graft. Thus aiding and perhaps accelerating the natural maturation and ligamentization process of the implanted graft tissue. Acceleration and improvement in graft maturation and strength would be a significant advancement in sports medicine allowing safer and earlier return to sports and activity.