Daley Ethan L H, Alford Andrea I, Miller Joshua D, Goldstein Steven A
1 Department of Biomedical Engineering, University of Michigan , Ann Arbor, Michigan.
Tissue Eng Part A. 2014 May;20(9-10):1416-25. doi: 10.1089/ten.TEA.2013.0420. Epub 2014 Jan 17.
Deer antlers are bony appendages that are annually cast and rapidly regrown in a seasonal process coupled to the reproductive cycle. Due to the uniqueness of this process among mammals, we reasoned that a fundamental characterization of antler progenitor cell behavior may provide insights that could lead to improved strategies for promoting bone repair. In this study, we investigated whether white-tailed deer antlerogenic progenitor cells (APC) conform to basic criteria defining mesenchymal stromal cells (MSC). In addition, we tested the effects of the artificial glucocorticoid dexamethasone (DEX) on osteogenic and chondrogenic differentiation as well as the degree of apoptosis during the latter. Comparisons were made to animal-matched marrow-derived MSC. APC and MSC generated similar numbers of colonies. APC cultures expanded less rapidly overall but experienced population recovery at later time points. In contrast to MSC, APC did not display adipogenic in vitro differentiation capacity. Under osteogenic culture conditions, APC and MSC exhibited different patterns of alkaline phosphatase activity over time. DEX increased APC alkaline phosphatase activity only initially but consistently led to decreased activity in MSC. APC and MSC in osteogenic culture underwent different time and DEX-dependent patterns of mineralization, yet APC and MSC achieved similar levels of mineral accrual in an ectopic ossicle model. During chondrogenic differentiation, APC exhibited high levels of apoptosis without a reduction in cell density. DEX decreased proteoglycan production and increased apoptosis in chondrogenic APC cultures but had the opposite effects in MSC. Our results suggest that APC and MSC proliferation and differentiation differ in their dependence on time, factors, and milieu. Antler tip APC may be more lineage-restricted osteo/chondroprogenitors with distinctly different responses to apoptotic and glucocorticoid stimuli.
鹿茸是每年脱落并在与生殖周期相关的季节性过程中迅速再生的骨质附属物。由于这一过程在哺乳动物中具有独特性，我们推断鹿茸祖细胞行为的基本特征可能会提供一些见解，从而有助于改进促进骨修复的策略。在本研究中，我们调查了白尾鹿鹿茸生成祖细胞（APC）是否符合定义间充质基质细胞（MSC）的基本标准。此外，我们测试了人工合成糖皮质激素地塞米松（DEX）对成骨和成软骨分化的影响以及在后者过程中细胞凋亡的程度。并与动物匹配的骨髓来源的MSC进行了比较。APC和MSC形成的集落数量相似。APC培养物总体上扩增速度较慢，但在后期时间点出现群体恢复。与MSC不同，APC在体外不显示脂肪生成分化能力。在成骨培养条件下，APC和MSC随时间呈现出不同的碱性磷酸酶活性模式。DEX仅在最初增加了APC的碱性磷酸酶活性，但持续导致MSC的活性降低。在成骨培养中的APC和MSC经历了不同的时间和DEX依赖性矿化模式，但在异位骨模型中，APC和MSC实现了相似的矿物质积累水平。在软骨形成分化过程中，APC表现出高水平的细胞凋亡但细胞密度没有降低。DEX降低了软骨形成APC培养物中的蛋白聚糖产生并增加了细胞凋亡，但对MSC有相反的作用。我们的结果表明，APC和MSC的增殖和分化在对时间、因子和环境的依赖性方面存在差异。鹿茸顶端APC可能是谱系限制更强的骨/软骨祖细胞，对凋亡和糖皮质激素刺激有明显不同的反应。
