Peripheral Blood Mesenchymal Stem Cells Combined with Modified Demineralized Bone Matrix Promote Pig Cartilage Defect Repair

Abstract

Objective: To investigate the mobilization of peripheral blood mesenchymal stem cells (PBMSCs) and whether a combination of PBMSCs and modified demineralized bone matrix (DBM) promoted the repair of cartilage lesions in a pig model. Methods: Pig PBMSCs were mobilized by the combined administration of granulocyte colony-stimulating factor (G-CSF) and the CXCR4 antagonist AMD3100. Colony formation was detected by the fibroblast colony-forming unit (CFU-F) count and the percentage of the CD45–CD90+ cell population by flow cytometry. The mobilized cells were identified as MSCs by their morphological characteristics, surface markers, and differentiation potentials. The composite scaffolds carrying BMP-2 and TGF-β3 chitosan sustained-release microspheres/DBM were prepared by emulsion cross-linking and the Urist method, and scanning electron microscopy (SEM) observation was performed. The model of pig cartilage defect was prepared, and gross observation, histological examination, immunohistochemistry, and O’Driscoll scoring were performed 4, 8, and 12 weeks postoperation. Results: After mobilization, the number of CFU-Fs in the peripheral blood in the experimental group (G-CSF + AMD3100) was significantly increased compared with the control group (p < 0.05). The proportion and total number of CD45–CD90+ cells were increased (p < 0.05). The mobilized stem cells had MSC characteristics. SEM of the new tissue-engineered cartilage showed that PBMSCs were evenly grown on the surface of the scaffold and microsphere morphology had no obvious change. Gross observation, histological examination, immunohistochemistry, and O’Driscoll score were better in the experimental group than in the other groups (p < 0.05). Conclusion: G-CSF + AMD3100 is an effective mobilization agent for PBMSCs. The new tissue-engineering cartilage constructed by two-factor sustained-release microspheres/DBM composite PBMSCs effected good repair of the cartilage defect in pigs.