Regeneration of hard tissue by the osteoblasts-collagen matrix complex

本研究探讨骨髓细胞-胶原基质复合物在体内是否具有诱导成骨作用。从大鼠股骨中分离骨髓细胞，在胶原基质上分化为成骨细胞。在常规培养条件下，骨髓细胞呈成纤维细胞形态，不表达典型的成骨细胞表型。相反，胶原基质上的骨髓细胞呈圆形，并表达高碱性磷酸酶活性和合成成骨细胞表型标志物骨钙素。然后将骨髓细胞-胶原基质复合物植入裸鼠皮下。植入后2周，胶原基质仍残留，两者间有结缔组织形成。第3周，骨形成，第4周在骨之间识别骨髓。在实验期间没有软骨形成。这些结果表明骨髓细胞-胶原基质以直接成骨的方式形成骨。骨髓细胞在植入前分化为成熟的成骨细胞是体内成骨的先决条件。骨髓细胞本身或前成骨细胞与胶原基质结合并植入体内时不诱导成骨。本课题成功地利用骨髓细胞和胶原基质诱导成骨。骨髓细胞和胶原基质形成骨的确切机制尚不清楚。因此，我们将继续这个项目，并希望开发一种新的治疗骨缺损的方法。

In this study, we investigated whether the bone marrow cells-collagen matrix complex induced bone in vivo. Bone marrow cells which were harvested from rat femur, differentiated to osteoblasts on collagen matrix. Under the conventional culture condition, bone marrow cells showed fibroblastic-form, and did not express the typical osteoblastic phenotypes. On the contrary, bone marrow cells on collagen matrix showed polygonal-form, and expressed high alkaline phosphatase activity and synthesized osteocalcin which were markers of osteoblastic phenotypes. Next bone marrow cells-collagen matrix complexes were implanted into the subcutaneous region of nude mouse. Until week two after implantation, collagen matrix remained, and connective tissue were formed between them. On week three, bone was formed, and bone marrow was recognized between bone on week four. No cartilage was formed for the duration of experiment. These findings indicate that bone marrow cells -collagen matrix formed bone in a direct bone formation manner. Bone marrow cells differentiated to mature osteoblasts before the implantation is a prerequisite for the bone formation in vivo. Bone marrow cells themselves or preosteoblasts did not induce bone when combined with collagen matrix and was implanted in vivo. In this project we succeeded to induce bone by the bonemarrow cells and collagen matrix. The precise mechanism of bone formation by bone marrow cells and collagen matrix is unclear. Therefore we are going to continue this project and would like to develop a new therapy for cure the bone defect.