Marinkovic Milos, Dai Qiuxia, Gonzalez Aaron O, Tran Olivia N, Block Travis J, Harris Stephen E, Salmon Adam B, Yeh Chih-Ko, Dean David D, Chen Xiao-Dong
Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, United States; Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, TX 78249, United States; Research Service, South Texas Veterans Health Care System, Audie Murphy VA Medical Center, San Antonio, TX 78229(,) United States.
Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, United States.
Matrix Biol. 2022 Aug;111:108-132. doi: 10.1016/j.matbio.2022.06.004. Epub 2022 Jun 23.
Previously, we showed that extracellular matrices (ECMs), produced ex vivo by various types of stromal cells, direct bone marrow mesenchymal stem cells (BM-MSCs) in a tissue-specific manner and recapitulate physiologic changes characteristic of the aging microenvironment. In particular, BM-MSCs obtained from elderly donors and cultured on ECM produced by young BM stromal cells showed improved quantity, quality and osteogenic differentiation. In the present study, we searched for matrix components that are required for a functional BM-MSC niche by comparing ECMs produced by BM stromal cells from "young" (≤25 y/o) versus "elderly" (≥60 y/o) donors. With increasing donor age, ECM fibrillar organization and mechanical integrity deteriorated, along with the ability to promote BM-MSC proliferation and responsiveness to growth factors. Proteomic analyses revealed that the matricellular protein, Cyr61/CCN1, was present in young, but undetectable in elderly, BM-ECM. To assess the role of Cyr61 in the BM-MSC niche, we used genetic methods to down-regulate the incorporation of Cyr61 during production of young ECM and up-regulate its incorporation in elderly ECM. The results showed that Cyr61-depleted young ECM lost the ability to promote BM-MSC proliferation and growth factor responsiveness. However, up-regulating the incorporation of Cyr61 during synthesis of elderly ECM restored its ability to support BM-MSC responsiveness to osteogenic factors such as BMP-2 and IGF-1. We next examined aging bone and compared bone mineral density and Cyr61 content of L4-L5 vertebral bodies in "young" (9-11 m/o) and "elderly" (21-33 m/o) mice. Our analyses showed that low bone mineral density was associated with decreased amounts of Cyr61 in osseous tissue of elderly versus young mice. Our results strongly demonstrate a novel role for ECM-bound Cyr61 in the BM-MSC niche, where it is responsible for retention of BM-MSC proliferation and growth factor responsiveness, while depletion of Cyr61 from the BM niche contributes to an aging-related dysregulation of BM-MSCs. Our results also suggest new potential therapeutic targets for treating age-related bone loss by restoring specific ECM components to the stem cell niche.
此前，我们发现，由各种类型的基质细胞在体外产生的细胞外基质（ECM）以组织特异性方式引导骨髓间充质干细胞（BM-MSC），并重现衰老微环境的生理变化特征。特别是，从老年供体获取并在年轻BM基质细胞产生的ECM上培养的BM-MSC，其数量、质量和成骨分化能力均有所改善。在本研究中，我们通过比较“年轻”（≤25岁）与“老年”（≥60岁）供体的BM基质细胞产生的ECM，寻找功能性BM-MSC微环境所需的基质成分。随着供体年龄的增加，ECM的纤维组织和机械完整性恶化，同时促进BM-MSC增殖和对生长因子反应的能力也下降。蛋白质组学分析显示，基质细胞蛋白Cyr61/CCN1存在于年轻的BM-ECM中，但在老年的BM-ECM中无法检测到。为了评估Cyr61在BM-MSC微环境中的作用，我们采用基因方法在年轻ECM产生过程中下调Cyr61的掺入，并在老年ECM中上调其掺入。结果显示，缺乏Cyr61的年轻ECM失去了促进BM-MSC增殖和对生长因子反应的能力。然而，在老年ECM合成过程中上调Cyr61的掺入，恢复了其支持BM-MSC对成骨因子如BMP-2和IGF-1反应的能力。接下来，我们检查了衰老骨骼，并比较了“年轻”（9-11月龄）和“老年”（21-33月龄）小鼠L4-L5椎体的骨矿物质密度和Cyr61含量。我们的分析表明，老年小鼠与年轻小鼠相比，骨矿物质密度低与骨组织中Cyr61含量减少有关。我们的结果有力地证明了ECM结合的Cyr61在BM-MSC微环境中的新作用，它负责维持BM-MSC的增殖和对生长因子的反应，而BM微环境中Cyr61的缺失导致BM-MSC与衰老相关的失调。我们的结果还表明，通过将特定的ECM成分恢复到干细胞微环境中，为治疗与年龄相关的骨质流失提供了新的潜在治疗靶点。
