3D-printed bredigite scaffolds with ordered arrangement structures promote bone regeneration by inducing macrophage polarization in onlay grafts

Our plain-English summary of 3D-printed bredigite scaffolds with ordered arrangement structures promote bone regeneration by inducing macrophage polarization in onlay grafts, by Y. Xuan, Y. Guo, L. Li, et al (Journal of Nanobiotechnology, 2024).

The study

• Authors: Y. Xuan, Y. Guo, L. Li, Yuzhang, C. Zhang, RuiJin, X. Yin, Z. Zhang
• Journal: Journal of Nanobiotechnology
• Published: 2024;22(1):102
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Bone tissue engineering scaffolds may provide a potential strategy for onlay bone grafts for oral implants. For determining the fate of scaffold biomaterials and osteogenesis effects, the host immune response is crucial. In the present study, bredigite (BRT) bioceramic scaffolds with an ordered arrangement structure (BRT-O) and a random morphology (BRT-R) were fabricated. The physicochemical properties of scaffolds were first characterized by scanning electron microscopy, mechanical test and micro-Fourier transform infrared spectroscopy. In addition, their osteogenic and immunomodulatory properties in an onlay grafting model were investigated. In vitro, the BRT-O scaffolds facilitated the macrophage polarization towards a pro-regenerative M2 phenotype, which subsequently facilitated the migration and osteogenic differentiation of bone marrow-derived mesenchymal stem cells. In vivo, an onlay grafting model was successfully established in the cranium of rabbits. In addition, the BRT-O scaffolds grafted on rabbit cranium promoted bone regeneration and CD68 + CD206 + M2 macrophage polarization. In conclusion, the 3D-printed BRT-O scaffold presents as a promising scaffold biomaterial for onlay grafts by regulating the local immune microenvironment.

© 2024. The Author(s).

In plain English

This study did not involve asbestos. It was a laboratory and animal study of 3D-printed scaffolds made from bredigite, a ceramic containing calcium, magnesium and silicon. The scaffolds were tested as a possible substitute for the bone blocks grafted onto the jaw before dental implants. The authors made two versions, one with an ordered structure (BRT-O) and one with a random structure (BRT-R). BRT-O was 1.69 times stronger under compression, and the two did not differ significantly in degradation or ion release. In cell cultures, mouse immune cells called macrophages grown on BRT-O showed more markers of the repair-linked M2 type. Fluid from these cells encouraged migration and bone-forming activity in mouse stem cells. In 27 male rabbits, scaffolds or the animal's own bone were grafted onto the skull. At six weeks no significant difference in bone measures was found between the scaffold groups. At 16 weeks, new bone area was 49.1 plus or minus 7.69% with BRT-O versus 12.2 plus or minus 3.94% with BRT-R, and bone mineral density was 1.20 times higher with BRT-O. The authors concluded that BRT-O scaffolds show potential for onlay bone grafts.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (in vitro) cell experiments combined with an animal experiment (rabbit skull onlay bone graft model)
• Who was studied: 27 male New Zealand white rabbits from the Experimental Animal Centre of the Ninth People's Hospital, China, given an autograft, BRT-R or BRT-O and euthanized at 2, 6 or 16 weeks. In vitro work used murine RAW264.7 macrophages and bone marrow-derived mesenchymal stem cells from male C57BL/6N mice.
• Exposure: No asbestos or fiber exposure was studied. The material tested was 3D-printed bredigite (Ca7MgSi4O16) bioceramic scaffolds with an ordered arrangement structure (BRT-O) or a random morphology (BRT-R), compared with autologous bone grafts.
• Main results:
  • The compressive strength of the BRT-O scaffold was 1.69 times that of the BRT-R scaffold.
  • BRT-O and BRT-R scaffolds did not differ significantly in pH, degradation or ion release in vitro.
  • Macrophages (RAW264.7 cells) on BRT-O scaffolds showed lower CD86 expression and higher CD206 expression than those on BRT-R scaffolds.
  • Stem cell proliferation did not differ significantly among groups, but RUNX2 mRNA expression was significantly higher in the BRT-O group than in the other two groups.
  • In rabbits at week six, micro-CT found no significant difference between scaffold groups in bone mineral density or BV/TV.
  • At week 16, bone mineral density was 482.2 plus or minus 26.81 mg HA per ccm in the BRT-O group versus 402.2 plus or minus 13.41 mg HA per ccm in the BRT-R group (1.20 times higher).
  • At week 16, new bone area was 49.1 plus or minus 7.69% in the BRT-O group versus 12.2 plus or minus 3.94% in the BRT-R group (p less than 0.01).
  • At two weeks in the BRT-O group, the reported values were 94.5 plus or minus 3.7 for CD68-positive cells and 67.6 plus or minus 4.7 for CD206-positive cells, and 19.3 plus or minus 1.1 for iNOS-positive M1 macrophages.
  • No animal deaths or obvious infections were observed.
• The authors' conclusion: The authors concluded that 3D-printed BRT scaffolds with an ordered arrangement structure induce macrophage polarization towards the pro-regenerative M2 phenotype and show potential for onlay bone grafts.
• Limitations the authors state:
  • Using bone scaffolds alone has limitations in bone regeneration outcomes.
  • Immune responses beyond macrophages, such as neutrophils and T cells, were not studied.
  • The role of individual ions released from the BRT scaffolds was not determined.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Tremolite.

Medical terms in this study, explained in our Lexicon: Macrophage, Scanning Electron Microscopy (SEM), Infrared Spectroscopy (IR), STEM.

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