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BACKGROUND: Based on the need of in situ tissue engineering regeneration in the field of meniscus regeneration, three-dimensional (3D) bioprinting technology can be used to construct a scaffold which can effectively combine recruitment bioactive factors and excellent materials. OBJECTIVE: To optimize the preparation process of polycaprolactone/methacrylate anhydride gelatin/meniscus extracellular matrix (PCL/GelMA/MECM) 3D bioprinting scaffold loaded with platelets derived growth factor-BB (PDGF-BB), and to test the sustained release properties of the growth factor and its effect on the migration and proliferation of the synovial mesenchymal stem cells. METHODS: Photosensitive bio-ink was prepared by GelMA/MECM. PCL scaffold and PCL/GelMA/MECM bio-scaffold were prepared by 3D bioprinting technology. Finally, PDGF-BB was loaded to fabricate functional bioprinting PCL/GelMA/MECM/PDGF scaffold, and then its mechanical properties and sustained release properties were tested. New Zealand white rabbit synovial mesenchymal stem cells were isolated and cultured. Transwell and CCK-8 assays were used to explore the effects of PCL scaffold, PCL/GelMA/MECM scaffold and PCL/GelMA/MECM/PDGF scaffold on the migration and proliferation of synovial mesenchymal stem cells, and single medium cultured cells were used as negative control. The third passage of synovial mesenchymal stem cells was inoculated on PCL scaffold, PCL/GelMA/MECM scaffold and PCL/GelMA/MECM/PDGF scaffold respectively. The viability, adhesion and growth of the cells on the three scaffolds were observed by confocal microscope and scanning electron microscope. RESULTS AND CONCLUSION: (1) There was no significant difference in tensile modulus and compression modulus between PCL/GelMA/MECM scaffolds and PCL scaffolds (P > 0.05). (2) PCL/GelMA/MECM/PDGF scaffolds had good sustained release performance, and PDGF-BB could be released continuously for up to 28 days. (3) Compared with the negative control group, PCL/GelMA/MECM scaffolds and PCL/GelMA/MECM/PDGF scaffolds could promote the migration of synovial mesenchymal stem cells, among which PCL/GelMA/MECM/PDGF scaffolds were more effective. (4) Compared with the negative control group, the cells cultured with PCL/GelMA/MECM scaffolds and PCL/GelMA/MECM/PDGF scaffolds proliferated faster after 4 and 7 days (P < 0.001), and the proliferative effect of PCL/GelMA/MECM/PDGF scaffolds was more obvious. (5) Dead/Live staining showed that the cells in each group had good activity, and the number of cells on the PCL/GelMA/MECM/PDGF scaffold was the highest. (6) Scanning electron microscope showed that the cells were attached to the surface of the three groups of scaffolds, and the cells on PCL/GelMA/MECM scaffolds and PCL/GelMA/MECM/PDGF scaffolds adhered to a large number of cells and secreted a large amount of extracellular matrix. (7) These results showed that the 3D bioprinted meniscus scaffold loaded with PDGF-BB had good mechanical properties and biocompatibility and could promote the migration and proliferation of synovial mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

BACKGROUND: Nanosized cell-type tissue-engineered bone is a good scaffold material possessing the merits of stem cells and nanomaterials to fabricate bone and soft tissue formation. OBJECTIVE: To explore the method of constructing nano-sized cell-type tissue-engineered bone and to explore its application in the repair of mandibular bone defects. METHODS: One New Zealand white rabbit was taken to isolate bone marrow stromal stem cells by centrifugation. Then, the cells were induced to differentiate into osteoblasts. Osteoblasts (3×108 /L, 10 μL) were inoculated into the prepared nano-phase hydroxyapatite/collagen composite to produce the nano-sized cell-type tissue-engineered bone. Another 20 New Zealand white rabbits were taken to make a unilateral puncture-type bone defect model of 15 mm×8 mm. These model rabbits were thereafter randomized into control and artificial bone groups (n=10 per group), followed by no intervention and implantation of nano-sized cell-type tissue-engineered bone, respectively. Repair effects were compared between the two groups. RESULTS AND CONCLUSION: (1) Under the inverted microscope, osteoblasts grew along the material in each group, and the number of cells increased with the prolongation of the culture time. (2) Under the scanning electron microscope, a large number of spindle- or polygon-shaped adherent cells grew well on the surface of the tissue-engineered bone. (3) The defect in the artificial bone group was lessened at 4 weeks after implantation and disappeared at 8 weeks after implantation, and there was no clear boundary with the surrounding tissue. In the control group, the defect size changed little at 4 weeks and reduced at 8 weeks after implantation, and a clear boundary with the surrounding tissue was observed. (4) Bone density, trabecular thickness and trabecular number were significantly higher in the artificial bone group than the control group at 4 and 8 weeks after implantation (P < 0.05). (5) At 4 weeks after implantation, many new bones at the defect site were detected in the artificial bone group, and a large number of mature bone cells were visible at 8 weeks. In the control group, a few osteoblasts were found at the defect site with low bone maturation at 4 and 8 weeks after implantation. These findings suggest that the implantation of nanosized cell-type tissue-engineered bone into the defect site can considerably promote defect healing and achieve ideal repair effects. [ABSTRACT FROM AUTHOR]