The Mechanism of Cartilage Regeneration by Buffy Coat and the Pre-clinical Study

Abstract BackgroundAutologous bone marrow buffy coat transplantation possesses obvious advantages in the therapy of large cartilage defects and osteoarthritis. However, there is no definite research on the specific effective components of bone marrow buffy coat and its mechanism of cartilage regeneration. Moreover, as the crucial cartilage regenerative cell in bone marrow buffy coat, mesenchymal stem cells(MSCs) are difficult to fix onto the damaged cartilage area without damaging the subchondral bone. We assessed the effect of using hyaluronic acid(HA) as a liquid scaffold mixed with autologous bone marrow buffy coat to fix cartilage defect.Methods and MaterialsWe extracted the bone marrow from the anterior superior iliac crest of the white New Zealand rabbit, centrifuged to obtain a buffy coat, and analyzed the components of buffy coat by ELISA. Buffy coat+HA group, MSC+HA group, MSC+TGF-β+HA group were cultured in vitro and observed by staining. In addition, we made damage to the femoral condyle of rabbits, and divided them into groups: HA group, buffy coat group, buffy coat with HA group. Each group was assessed for cartilage regeneration by visual observation, histological and immunohistochemical analysis at 4 weeks and 8 weeks, and biochemical analysis at 8 weeks postoperatively. One-way ANOVA and LSD were used for statistic analysis.ResultsBuffy coat have a variety of growth factors, inflammatory factors and anti-inflammatory factors that stimulate the MSCs’ regeneration. Buffy coat can differentiate into cartilage without TGF-β stimulation in vitro. The cartilage regeneration ability of buffy coat and buffy coat+HA is strong, and the combination of buffy coat and liquid scaffold HA can make cartilage formation ability more stable in vivo.ConclusionMSC, multiple growth factors and cytokines in buffy coat synergistically promote cartilage regeneration. Liquid scaffold HA enhances the effect of buffy coat on cartilage attachment and regeneration of cartilage defects.