Grzesiak Jakub, Śmieszek Agnieszka, Marycz Krzysztof
Electron Microscopy Laboratory, Wroclaw Research Centre EIT+, Stabłowicka 147, 54-066 Wrocław, Poland.
Electron Microscopy Laboratory, Wroclaw University of Environmental and Life Sciences, Kożuchowska 5b, 51-631 Wrocław, Poland.
Cell Biosci. 2017 Jan 3;7:2. doi: 10.1186/s13578-016-0128-0. eCollection 2017.
Osteogenic differentiation of mesenchymal stem cells has been extensively investigated with regards to different aspects, including the analysis of cell intracellular and extracellular proteome, cell gene expression pattern, and morphology. During the osteogenic differentiation, osteoblasts produce and release specific proteins, like osteocalcin and osteopontin. Simultaneously, cells produce the extracellular matrix (ECM) that resembles the bone ECM, with high quantity of calcium and phosphorus. We focused on the ultrastructural changes occurring during the osteogenic differentiation of MSC cultured in alginate hydrogel.
The analysis revealed that during the osteogenic differentiation the most of cells become dead, and these dead cells contain large quantities of calcium and deposition is strictly connected with the cellular death and small membrane vesicles released by cells. Cell organelles were not present within differentiated cells, while in cells from non-osteogenic group the cellular ultrastructure was proper, with single nuclei, endoplasmic reticulum and numerous mitochondria.
The ECM synthesis and deposition during the osteogenic differentiation of MSC involves cellular programmed death. The small membrane vesicles become the mineralization sites of formed bone ECM.
间充质干细胞的成骨分化已在不同方面进行了广泛研究，包括细胞内和细胞外蛋白质组分析、细胞基因表达模式以及形态学。在成骨分化过程中，成骨细胞产生并释放特定蛋白质，如骨钙素和骨桥蛋白。同时，细胞产生类似于骨细胞外基质（ECM）的细胞外基质，其中含有大量的钙和磷。我们重点研究了在藻酸盐水凝胶中培养的间充质干细胞成骨分化过程中发生的超微结构变化。
分析表明，在成骨分化过程中，大多数细胞死亡，这些死亡细胞含有大量钙，且钙沉积与细胞死亡以及细胞释放的小膜泡密切相关。分化细胞内不存在细胞器，而非成骨组细胞的细胞超微结构正常，有单个细胞核、内质网和众多线粒体。
间充质干细胞成骨分化过程中的细胞外基质合成与沉积涉及细胞程序性死亡。小膜泡成为形成的骨细胞外基质的矿化位点。
