Abstract: BACKGROUND: Three-dimensional printed polylactic-co-glycolic acid/hydroxyapatite scaffold is widely used in bone defect repair, because of personalised shapes, excellent osteoconductivity and biocompatibility. However, implanted scaffolds have an adverse effect on bone tissue regeneration due to their poor ability to induce neovascularisation.
OBJECTIVE: To verify the osteogenic and angiogenic effects of the desferrioxamine-loaded polylactic-co-glycolic acid/hydroxyapatite composite scaffold.
METHODS: The polylactic-co-glycolic acid/hydroxyapatite composite scaffold (control scaffold) and desferrioxamine-loaded polylactic-co-glycolic acid/hydroxyapatite composite scaffold (experimental scaffold) could be fabricated using a low-temperature three-dimensional-printing technique. The microstructure and in vitro degradation of the scaffold were characterized. At the same time, the sustained-release properties of the deferriamine from the desferrioxamine-loaded polylactic-co-glycolic acid/hydroxyapatite composite scaffold were detected. The rat derived adipose stem cells were seeded on the two groups of scaffolds respectively, and the cells inoculated on the culture plate were used as the control group. Cytoskeleton observation, cell proliferation test, staining of live and dead cells, qRT-PCR detection, and immunofluorescence analysis were performed.
RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that the control scaffold and experimental scaffold had uniformly distributed macroporous structure, and there was no obvious difference. The pore size of the scaffolds was about 510 μm. (2) In vitro degradation experiments showed that the degradation rate of the control scaffold and experimental scaffold was less than 10% at 8 weeks, and the pH value remained relatively stable and always remained at 7.1 to 7.4. (3) In vitro sustained-release experiments showed that the deferoxamine had a burst release from the experimental scaffolds within 2 weeks and sustained a steady level, at about 75% within 8 weeks. (4) It can be seen under a fluorescent inverted microscope that the adipose stem cells on the two scaffolds were spindle-shaped and spread larger. Scanning electron microscopy showed that there were many pseudopods of cells on both scaffolds, and the cells were spread well on the surface of the scaffolds. (5) CCK-8 assay showed there was no difference in cell proliferation among the three groups (P < 0.05). (6) qRT-PCR showed that compared with the control group and control scaffold group, the gene expression of vascular endothelial growth factor and osteocalcin in the experimental scaffold group was increased (P < 0.01). Immunofluorescence analysis showed that compared with the control group and the control scaffold group, the protein expression of vascular endothelial growth factor and osteocalcin in the experimental scaffold group increased (P < 0.01). (7) The results showed that the three-dimensional-printed desferrioxamine-loaded polylactic-co-glycolic acid/hydroxyapatite composite scaffold was expected to play a good dual role in osteogenesis and vascularization.

Key words: polylactic-co-glycolic acid, hydroxyapatite, osteogenesis, vascularisation, three-dimensional printing, desferrioxamine, adipose derived stem cells, composite scaffolds