Mechanism study of structural functional dual biomimetic composite bone scaffold for repair of mandibular defects in rabbits

Objectives: Mandibular issues resulting from injury, gum disease, or congenital defects can restrict chewing ability, impair speech, and cause facial disfigurement, significantly affecting the patient's quality of life. In our previous studies, we investigated the optimum porosity of triply periodic minimal surfaces (TPMS) scaffolds and verified the clinical potential of TPMS scaffolds containing injectable platelet-rich fibrin (I-PRF) and stromal cell-derived factor-1 (SDF-1) (SIT scaffold). This study focuses on the potential mechanisms of SIT bone tissue engineering scaffolds. Methods: Surface structures with a 70% porosity were created using the Matlab R2020a program. Scaffolds were fabricated using digital laser processing. To evaluate the effects on treated F-actin tissues, rabbit bone marrow mesenchymal stem cells were inoculated on SIT scaffolds for 14 days. The morphological changes of individual cells were photographed at 60x magnification using confocal microscopy and quantified with ImageJ software. Histological structures were observed using ALP immunohistochemical staining, Alcian blue, and Masson-Goldner staining. Double-end sequencing in PE150 mode was performed using the Illumina NovaSeq™ 6000 according to standard procedures. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), protein-protein interaction (PPI), and gene set variation analysis (GSVA) were conducted to support the interpretation of gene functions. RT-qPCR was performed to confirm the expression of genes of interest. Finally, cells on different samples were examined by confocal laser scanning microscopy to observe c-Jun expression. Results: Confocal imaging and quantitative analysis showed that bone marrow mesenchymal stem cells supported by the SIT scaffold had a greater tendency to differentiate into osteogenesis than those supported by the T scaffold or the control group. The SIT group exhibited the most intense ALP staining. The expression of angiogenesis-related factors VEGFA was significantly upregulated in T and SIT groups. Osteogenic gene RUNX2 and c-Fos/c-Jun pathway genes FOS/JUN were significantly upregulated in the SIT group. GSVA revealed that the WNT signaling pathway and MAPK signaling pathway were more active in the SIT group. Gene expression was validated by qRT-PCR. Immunofluorescence showed that the c-Jun is highly expressed in newly formed capillaries in the SIT group.