Bioreactor manufactured cartilage grafts repair acute and chronic osteochondral defects in large animal studies

Objectives Bioreactor‐based production systems have the potential to overcome limitations associated with conventional tissue engineering manufacturing methods, facilitating regulatory compliant and cost‐effective production of engineered grafts for widespread clinical use. In this work, we established a bioreactor‐based manufacturing system for the production of cartilage grafts. Materials & Methods All bioprocesses, from cartilage biopsy digestion through the generation of engineered grafts, were performed in our bioreactor‐based manufacturing system. All bioreactor technologies and cartilage tissue engineering bioprocesses were transferred to an independent GMP facility, where engineered grafts were manufactured for two large animal studies. Results The results of these studies demonstrate the safety and feasibility of the bioreactor‐based manufacturing approach. Moreover, grafts produced in the manufacturing system were first shown to accelerate the repair of acute osteochondral defects, compared to cell‐free scaffold implants. We then demonstrated that grafts produced in the system also facilitated faster repair in a more clinically relevant chronic defect model. Our data also suggested that bioreactor‐manufactured grafts may result in a more robust repair in the longer term. Conclusion By demonstrating the safety and efficacy of bioreactor‐generated grafts in two large animal models, this work represents a pivotal step towards implementing the bioreactor‐based manufacturing system for the production of human cartilage grafts for clinical applications

Bone morphogenetic protein (BMP)1-3 enhances bone repair

Members of the astacin family of metalloproteinases such as human bone morphogenetic protein 1 (BMP-1) regulate morphogenesis by processing precursors to mature functional extracellular matrix (ECM) proteins and several growth factors including TGFβ, BMP2, BMP4 and GFD8. We have recently discovered that BMP1-3 isoform of the Bmp-1 gene circulates in the human plasma and is significantly increased in patients with acute bone fracture. We hypothesized that circulating BMP1-3 might have an important role in bone repair and serve as a novel bone biomarker. When administered systemically to rats with a long bone fracture and locally to rabbits with a critical size defect of the ulna, recombinant human BMP1-3 enhanced bone healing. In contrast, neutralization of the endogenous BMP1-3 by a specific polyclonal antibody delayed the bone union. Invitro BMP1-3 increased the expression of collagen type I and osteocalcin in MC3T3-E(1) osteoblast like cells, and enhanced the formation of mineralized bone nodules from bone marrow mesenchymal stem cells. We suggest that BMP1-3 is a novel systemic regulator of bone repair