Background: Currently, the use of xenogeneic and allogeneic compounds in the treatment of musculoskeletal diseases is common. Repairing bone and cartilage remains a significant challenge for orthopedic surgeons. One of the principal goals of tissue engineering is the development of appropriate scaffolds that can promote tissue regeneration. Various cells and genes are involved in bone and cartilage regeneration, and new scaffolds can induce these processes during osteoregeneration. Objectives: The aim of this study is to evaluate the effects of umbilical cord blood stem cells (USCs) and platelet-rich fibrin (PRF) using acellular scaffolds in the repair of knee defects in rabbits. Methods: In this study, the femoral patella of 12 male New Zealand rabbits was drilled, and they were divided into four groups: (1) control (rabbits with femoral defects), (2) acellular osteochondral (AO), (3) AO + PRF, and (4) AO + USCs / platelet-rich fibrin. Different scaffolds were implanted into their knees, and after six months, histological evaluations were conducted. To further investigate the effects of scaffolds on bone and cartilage, gene expression levels of Col 1, Col X, Runx2, SOX9, and ALP were measured using real-time PCR. Results: All the implanted materials contributed to knee repair. In terms of statistical analysis, the use of USCs and platelet-rich fibrin with natural scaffolds such as Acellular Osteochondral provided better results for repairing bone and cartilage. The evaluation of specific bone regeneration genes (COLI, RUNX2) and the histological results from the implanted site in experimental osteochondral defects indicated that the most effective knee repair occurred in the group treated with cell-free osteochondral scaffolds, USCs, and platelet-rich fibrin. Conclusions: This study demonstrates that the combination of biomaterials and xenografts can accelerate the regeneration process.