Regeneration of rabbit calvarial defects using cells-implanted nano-hydroxyapatite coated silk scaffolds

Abstract

BackgroundThe aim of this study was to characterize the efficacy of nano-hydroxyapatite-coated silk fibroin constructs as a scaffold for bone tissue engineering and to determine the osteogenic effect of human dental pulp and periodontal ligament derived cells at an early stage of healing in rabbits. 3D silk fibroin constructs were developed and coated using nano-hydroxyapatite crystals. Dental pulp and periodontal ligament cells from extracted human third molars were cultured and seeded onto the silk scaffolds prior to in vivo implantation into 8 male New Zealand White rabbits. Four circular windows 8 mm in diameter were created in the calvarium of each animal. The defects were randomly allocated to the groups; (1) silk scaffold with dental pulp cells (DPSS), (2) silk scaffold with PDL cells (PDLSS), (3) normal saline-soaked silk scaffold (SS), and (4) empty control. The animals were sacrificed 2 (n = 4) or 4 weeks (n = 4) postoperatively. The characteristics of the silk scaffolds before and after cell seeding were analyzed using SEM. Samples were collected for histologic and histomorphometic analysis. ANOVA was used for statistical analysis.ResultHistologic view of the experimental sites showed well-maintained structure of the silk scaffolds mostly unresorbed at 4 weeks. The SEM observations after cell-seeding revealed attachment of the cells onto silk fibroin with production of extracellular matrix. New bone formation was observed in the 4 week groups occurring from the periphery of the defects and the silk fibers were closely integrated with the new bone. There was no significant difference in the amount of bone formation between the SS group and the DPSS and PDLSS groups.ConclusionWithin the limitations of this study, silk scaffold is a biocompatible material with potential expediency as an osteoconductive scaffold in bone tissue engineering. However, there was no evidence to suggest that the addition of hDPCs and hPDLCs to the current rabbit calvarial defect model can produce an early effect in augmenting osteogenesis.

Natural and Synthetic Polymers for Bone Scaffolds Optimization

“…Instead, other researchers tested nanohydroxyapatite-coated silk substrates in rabbit model. They reported good scaffold stability, cell attachments and new bone formation in four weeks [84]. The hydroxyapatite inclusion has been also used to enhance the mechanical properties of the silk fibroin scaffold, promoting mesenchymal stem cells differentiation and bone regeneration [85].…”

Insights into the angiogenic effects of nanomaterials: mechanisms involved and potential applications

“…Therefore, researchers are working on fabricating novel micronano scaffolds to drive angiogenesis and promote bone regeneration [20]. The common method is infiltration of nanoparticles, nanosheets or nanofibres in different natural or synthetic materials, such as bioceramics [21,22], polycaprolactone [23], chitosan [24], silk fibroin [25] and collagen [26][27][28]. The composition of nanomaterials improves the mechanical properties and surface hydrophilicity of the bone tissue engineering scaffold, which is beneficial to the growth and adhesion of human umbilical vein endothelial cells (HUVECs) [29].…”

Is There a Role for Neural Crest Stem Cells in Periodontal Regeneration?

“…PDLSC expressed MSC-related cell surface markers, CD10, CD13, CD26, CD29, CD44, CD71, CD73, CD90, CD105, CD106, CD146, CD166, CD349, STRO-1, STRO-3, and TNAP/MSCA-1 [50][51][52], as well as neural crest cell-related marker genes Snail, Slug, Twist, SOX9, SOX10, Nestin, p75NTR, CD49d, and Tuj1 [53,54]. PDLSC cultured in osteogenic medium can form mineralized nodules and demonstrate an increase in bonerelated gene expression [49] and in vivo transplantation of PDLSC into calvarial defects revealed the new bone formation within the defects [55,56], suggesting that PDLSC can differentiate into osteoblasts. Additionally, several factors regulate the osteoblastic differentiation capacity of PDLSC.…”