Architecture mechanics mediated osteogenic progression in bone regeneration of artificial scaffolds

Scaffold architecture exerts a considerable influence on the osteogenic effect through stress transmission, as the deformation of scaffolds alters the mechanical microenvironment of cells adhering to scaffold surface. Despite extensive researches on bone regeneration influenced by scaffold architecture, present studies have not addressed the biological mechanism underlying scaffold architecture-induced stress stimulation (SASS) on cells yet, posing a great challenge in revealing the biomechanical cues between scaffold architecture and osteogenic progression. Therefore, Graphite (GP), Fullerene (FL), and Diamond (DM) scaffolds with gradient stress-stimulation to cells after deformation were prepared. The cellular biomechanical mechanisms of SASS through single-cell RNA sequencing indicated that architectures providing SASS can induce the enrichment of focal adhesion and osteogenic differentiation pathways of bone mesenchymal stem cells, and balance bone resorption of osteoclasts and bone formation of osteoblasts. Besides, SASS enhances bone regeneration for repairing critical-sized defects in vivo. These results provide insights for artificial bone scaffold design and clarify the biomechanical cues between SASS and osteogenic progression. Overall design: Our team designed three scaffolds based on the crystal structures of carbon, that is, graphite (GP), fullerene (FL), and diamond (DM) architectures. One month after the implantation of GP, FL, and DM scaffolds in the femur, the bone tissue at the defect site was removed and single-cell RNA sequencing was performed.

支架结构通过应力传递对成骨效应产生显著影响，支架形变会改变黏附于其表面的细胞所处的机械微环境。尽管已有大量研究探讨了支架结构对骨再生的影响，但目前尚未阐明支架结构诱导的应力刺激（scaffold architecture-induced stress stimulation, SASS）的细胞生物学机制，这为揭示支架结构与成骨进程之间的生物力学信号关联带来了极大挑战。为此，本研究制备了变形后可对细胞产生梯度应力刺激的石墨（Graphite, GP）、富勒烯（Fullerene, FL）及金刚石（Diamond, DM）支架。通过单细胞RNA测序（single-cell RNA sequencing）分析SASS的细胞生物力学机制后发现，可产生SASS的支架结构能够诱导骨髓间充质干细胞的黏着斑与成骨分化通路富集，并同时平衡破骨细胞的骨吸收与成骨细胞的骨形成功能。此外，SASS可促进体内临界骨缺损修复过程中的骨再生。本研究结果为人工骨支架的设计提供了新思路，并阐明了SASS与成骨进程之间的生物力学信号关联。实验整体设计：本团队基于碳的晶体结构设计了三类支架，即石墨（Graphite, GP）、富勒烯（Fullerene, FL）与金刚石（Diamond, DM）结构支架。将GP、FL及DM支架植入股骨后1个月，取下缺损部位的骨组织并进行单细胞RNA测序分析。