Autologous Peripheral Blood Stem Cells With Adjuvant Hyaluronic Acid Enhance Cartilage Repair After Subchondral Drilling in a Sheep Model.

Purpose: To determine histologically whether intra-articular injections of autologous peripheral blood stem cells (PBSC) and adjuvant hyaluronic acid (HA) after subchondral drilling result in better articular cartilage repair. Methods: Fifteen sheep (aged 12-36 months) were included in this study. An 8-mm full-thickness cartilage defect was created. There were 3 groups: group A, which comprised 5 control (subchondral drilling only); group B, which comprised 5 subchondral drilling + HA (3 injections); and group C, which comprised 5 subchondral drilling + PBSC + HA (3 injections). Each injection was given intra-articularly at 7 days apart. Animals were killed humanely at 6 months after operation. The left stifle joint was examined macroscopically as well as histologically (hematoxylin and eosin, safranin-O, collagen type 1 and 2, International Cartilage Regeneration & Joint Preservation Society [ICRS] II scale). Results: All the animals survived the duration of the study. Macroscopic evaluation showed the presence of repair tissues in all groups, although the chondral defects were not completely filled with repair cartilage. Greater ICRS II scores indicate better chondrogenesis. Group C (902 ± 229) showed significantly greater ICRS II scores compared with group A (536 ± 81) and group B (563 ± 83), with P values of .014 and .016, respectively. However, the scores for group C were lower to those of normal cartilage (1266 ± 35), with a P of .014. Conclusions: In this sheep model, postoperative intra-articular injections of autologous PBSCs with HA were associated with better histologic cartilage repair after subchondral drilling when compared with HA alone, as assessed using the ICRS II scoring system. Clinical Relevance: This large animal study shows that intra-articular injections of autologous PBSC combined with HA are associated with improved histologic features of cartilage repair after subchondral drilling, supporting further investigation of this approach in preclinical models and the findings may have relevance in guiding future treatment strategies for cartilage defects in humans.