骨髓是复杂的结构,含有异源性细胞,这使得使用人造支架很难再生。在之前的研究中,我们成功地开发了蜂窝状磷酸三钙(TCP),这是一个圆柱形支架,蜂窝排列的直孔,我们证明了具有300和500μm孔径的TCP(300TCP和500TCP)在孔内诱导骨髓结构。在这项研究中,我们使用蜂窝状TCP检查了具有稳态骨代谢的骨髓的最佳支架结构。将300TCP和500TCP移植到大鼠肌肉中,并对骨髓形成进行组织学评估。CD45,CD34,Runt相关转录因子2(Runx2),c-kit单染色,Runx2/N-钙黏着蛋白,进行c-kit/Tie-2双重染色。骨髓结构的面积,其中包括CD45(+)圆形造血细胞和CD34(+)正弦血管,300TCP比500TCP大。此外,在TCP内形成的骨组织表面观察到Runx2(+)成骨细胞和c-kit(+)造血干细胞。在Runx2(+)成骨细胞中,纺锤形N-cadherin(+)细胞与c-kit(+)Tie-2(+)造血干细胞联合存在于TCP内形成的骨组织上,形成了类似于体内的造血干细胞生态位。因此,具有300μm孔径的蜂窝状TCP可以是具有最佳几何结构的人造支架,作为用于骨髓形成的支架。
Bone marrow is complex structure containing heterogenetic cells, making it difficult to regenerate using artificial scaffolds. In a previous study, we succeeded in developing honeycomb tricalcium phosphate (TCP), which is a cylindrical scaffold with a honeycomb arrangement of straight pores, and we demonstrated that TCP with 300 and 500 μm pore diameters (300TCP and 500TCP) induced bone marrow structure within the pores. In this study, we examined the optimal scaffold structure for bone marrow with homeostatic bone metabolism using honeycomb TCP. 300TCP and 500TCP were transplanted into rat muscle, and bone marrow formation was histologically assessed. Immunohistochemistry for CD45, CD34, Runt-related transcription factor 2 (Runx2), c-kit single staining, Runx2/N-cadherin, and c-kit/Tie-2 double staining was performed. The area of bone marrow structure, which includes CD45(+) round-shaped hematopoietic cells and CD34(+) sinusoidal vessels, was larger in 300TCP than in 500TCP. Additionally, Runx2(+) osteoblasts and c-kit(+) hematopoietic stem cells were observed on the surface of bone tissue formed within TCP. Among Runx2(+) osteoblasts, spindle-shaped N-cadherin(+) cells existed in association with c-kit(+)Tie-2(+) hematopoietic stem cells on the bone tissue formed within TCP, which formed a hematopoietic stem cell niche similar to as in vivo. Therefore, honeycomb TCP with 300 μm pore diameters may be an artificial scaffold with an optimal geometric structure as a scaffold for bone marrow formation.