Tendon graft revitalization using adult anterior cruciate ligament (ACL)-derived CD34+ cell sheets for ACL reconstruction

As a new strategy for enhancing recovery after anterior cruciate ligament (ACL) reconstruction, we developed a cell sheet wrapped graft using ACL-derived CD34+ cells. Our results from an ex vivo cell migration assay demonstrated gradual cell migration into the graft from the cell sheet, and an enzyme-linked immunosorbent assay indicated that the cell sheet cultures secreted a significantly greater amount of VEGF than typical monolayer cultures. In the in vivo study, the rats received one of three possible ACL reconstruction treatments; 1) a tendon graft wrapped in an ACL-derived CD34+ cell sheet, 2) a tendon graft and ACL-derived CD34+ cell injection, or 3) the control group that received just the tendon graft. The in vivo studies revealed that the ACL-derived CD34+ cell sheet wrapped grafts demonstrated a greater number of the cells derived from the cell sheets incorporated within the bone tunnel site and grafted tendon. We believe the incorporated CD34+ cells enhanced the healing of both the bone–tendon junction and the grafted tendon in the reconstructed rat ACLs by increasing proprioceptive recovery, graft maturation, and biomechanical strength. ACL-derived CD34+ cell sheet wrapped grafts could become a promising strategy to revitalize tendon autografts and recovery after ACL reconstruction resulting in superior and quicker recovery in patients requiring ACL reconstruction.