Characterization of bone marrow aspirate concentrate with thrombin used for repairing osteochondral lesions of the talus

Introduction: Bone marrow aspirate concentrate (BMAC) is an autologous biological augment used in the treatment of osteochondral lesions of the talus.Several studies have reported the short-term efficacy of BMAC for repair of osteochondral lesions of the talus, however, there is minimal regulation of the autologous products' potency and "release criteria" for clinical use.Moreover, the mechanism of action of BMAC therapy is poorly understood.Objectives: This study aimed to investigate the composition of BMAC and BMAC mixed with thrombin (B+T), prepared according to commercial Complete Cartilage Regeneration kit protocols, linked to functional outcome data.Methods: Bone marrow aspirate, BMAC, and B+T samples (n = 16) were obtained for cellular analysis via a hematology analyzer and colony-forming unit-fibroblast assay.Molecular composition was assessed via a multiplex 27-cytokine assay and enzyme-linked immunosorbent assay (n = 12).Spearman rank correlation was used to assess the relationship between both cellular and molecular composition with patient functional outcomes.Results: Mesenchymal stem cells and platelets were concentrated in BMAC compared with bone marrow aspirate, but were reduced significantly after addition of thrombin.Cytokines and growth factors also decreased in concentration in B+T, however, platelet-derived growth factor-BB and interleukin-1 receptor alpha were significantly increased.Basic fibroblast growth factor, Eotaxin, IL-4, and IL-17 were found to have a positive correlation with worsening Manchester-Oxford Foot and Ankle Questionnaire (MOXFQ) 7 months postoperation.Conclusions: This study provides insight into the cellular and molecular characteristics of BMAC and B+T, highlighting donor heterogeneity and the importance of profiling autologous products prior to treatment.