In Vitro and In Vivo Evaluation of Osteogenesis of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells on Partially Demineralized Bone Matrix

The osteogenic differentiation potential of umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) has been documented previously, and partially demineralized bone matrix (pDBM) represents a promising candidate for bone tissue engineering scaffolds. In this study, pDBM scaffolds derived from porcine cancellous bone were evaluated for their ability to support human UCB-MSCs osteogenic differentiation in vitro and bone-forming capacity in vivo to assess the potential use of UCB-MSCs in bone tissue engineering applications. MSCs were isolated from full-term human UCB and expanded, and their cell surface antigen markers and multilineage capability to differentiate into osteoblasts, chondrocytes, and adipocytes were analyzed. The in vitro proliferation and osteogenic differentiation of UCB-MSCs loaded onto the three-dimensional pDBM scaffolds were determined. Critical-sized full-thickness circular defects (5 mm in diameter) created bilaterally in the parietal bones of athymic rats were treated with one of the following: osteogenically induced UCB-MSC/pDBM composites (Group A, n = 8), noninduced UCB-MSC/pDBM composites (Group B, n = 8), pDBM alone (Group C, n = 8), or left untreated (Group D, n - 8). Microcomputed tomography analysis showed that new bone was formed in Group A at 6 weeks postimplantation, and greater bone volume and density were found after 12 weeks. In other groups, new bone formation was not evident after 6 weeks, and no bone union was found at 12 weeks. Histological examination revealed that the defect was repaired by tissue-engineered bone in Group A at 12 weeks, and fibrous union was observed in Groups B, C, and D. These results demonstrate that pDBM can support osteogenic differentiation of human UCB-MSCs in vitro and in vivo, and UCB-MSCs may serve as an alternative cell source for bone tissue engineering and regeneration.