Yoon Hyejin, Park Yongkuk, Kwak Jun-Goo, Lee Jungwoo
Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, United States.
Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, United States.
JBMR Plus. 2024 Jun 17;8(8):ziae080. doi: 10.1093/jbmrpl/ziae080. eCollection 2024 Aug.
Bone is a dynamic mineralized tissue that undergoes continuous turnover throughout life. While the general mechanism of bone mineral metabolism is documented, the role of underlying collagen structures in regulating osteoblastic mineral deposition and osteoclastic mineral resorption remains an active research area, partly due to the lack of biomaterial platforms supporting accurate and analytical investigation. The recently introduced osteoid-inspired demineralized bone paper (DBP), prepared by 20-μm thin sectioning of demineralized bovine compact bone, holds promise in addressing this challenge as it preserves the intrinsic bony collagen structure and retains semi-transparency. Here, we report on the impact of collagen structures on modulating osteoblast and osteoclast-driven bone mineral metabolism using vertical and transversal DBPs that exhibit a uniaxially aligned and a concentric ring collagen structure, respectively. Translucent DBP reveals these collagen structures and facilitates longitudinal tracking of mineral deposition and resorption under brightfield microscopy for at least 3 wk. Genetically labeled primary osteogenic cells allow fluorescent monitoring of these cellular processes. Osteoblasts adhere and proliferate following the underlying collagen structures of DBPs. Osteoblastic mineral deposition is significantly higher in vertical DBP than in transversal DBP. Spatiotemporal analysis reveals notably more osteoblast adhesion and faster mineral deposition in vascular regions than in bone regions. Subsequent osteoclastic resorption follows these mineralized collagen structures, directing distinct trench and pit-type resorption patterns. In vertical DBP, trench-type resorption occurs at an 80% frequency, whereas transversal DBP shows 35% trench-type and 65% pit-type resorption. Our studies substantiate the importance of collagen structures in regulating mineral metabolism by osteogenic cells. DBP is expected to serve as an enabling biomaterial platform for studying various aspects of cellular and extracellular bone remodeling biology.
骨骼是一种动态矿化组织，在整个生命过程中持续进行更新。虽然骨矿物质代谢的一般机制已有文献记载，但潜在的胶原蛋白结构在调节成骨细胞矿物质沉积和破骨细胞矿物质吸收中的作用仍是一个活跃的研究领域，部分原因是缺乏支持精确分析研究的生物材料平台。最近推出的类骨样脱矿骨纸（DBP），通过对脱矿牛密质骨进行20微米薄片切割制备而成，有望应对这一挑战，因为它保留了内在的骨胶原结构并保持半透明性。在此，我们报告了使用分别呈现单轴排列和同心环胶原结构的纵向和横向DBP，胶原蛋白结构对调节成骨细胞和破骨细胞驱动的骨矿物质代谢的影响。半透明的DBP揭示了这些胶原结构，并有助于在明场显微镜下纵向追踪矿物质沉积和吸收至少3周。基因标记的原代成骨细胞允许对这些细胞过程进行荧光监测。成骨细胞沿着DBP的潜在胶原结构粘附和增殖。纵向DBP中的成骨细胞矿物质沉积明显高于横向DBP。时空分析显示，与骨区域相比，血管区域的成骨细胞粘附明显更多，矿物质沉积更快。随后的破骨细胞吸收遵循这些矿化胶原结构，形成不同的沟槽型和凹坑型吸收模式。在纵向DBP中，沟槽型吸收的发生率为80%，而横向DBP显示35%的沟槽型和65%的凹坑型吸收。我们的研究证实了胶原蛋白结构在调节成骨细胞矿物质代谢中的重要性。预计DBP将作为一种有潜力的生物材料平台，用于研究细胞和细胞外骨重塑生物学的各个方面。
