Hebb John H, Ashley Jason W, McDaniel Lee, Lopas Luke A, Tobias John, Hankenson Kurt D, Ahn Jaimo
Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 3737 Market Street, Suite 6121, Philadelphia, Pennsylvania, 19104.
Department of Biology, College of Science, Technology, Engineering, and Mathematics, Eastern Washington University, Cheney, Washington.
J Orthop Res. 2018 Jan;36(1):149-158. doi: 10.1002/jor.23652. Epub 2017 Oct 9.
Geriatric fractures take longer to heal and heal with more complications than those of younger patients; however, the mechanistic basis for this difference in healing is not well understood. To improve this understanding, we investigated cell and molecular differences in fracture healing between 5-month-old (young adult) and 25-month-old (geriatric) mice healing utilizing high-throughput analysis of gene expression. Mice underwent bilateral tibial fractures and fracture calluses were harvested at 5, 10, and 20 days post-fracture (DPF) for analysis. Global gene expression analysis was performed using Affymetrix MoGene 1.0 ST microarrays. After normalization, data were compared using ANOVA and evaluated using Principal Component Analysis (PCA), CTen, heatmap, and Incromaps analysis. PCA and cross-sectional heatmap analysis demonstrated that DPF followed by age had pronounced effects on changes in gene expression. Both un-fractured and 20 DPF aged mice showed increased expression of immune-associated genes (CXCL8, CCL8, and CCL5) and at 10 DPF, aged mice showed increased expression of matrix-associated genes, (Matn1, Ucma, Scube1, Col9a1, and Col9a3). Cten analysis suggested an enrichment of CD8+ cells and macrophages in old mice relative to young adult mice and, conversely, a greater prevalence of mast cells in young adult mice relative to old. Finally, consistent with the PCA data, the classic bone healing pathways of BMP, Indian Hedgehog, Notch and Wnt clustered according to the time post-fracture first and age second.
Greater understanding of age-dependent molecular changes with healing will help form a mechanistic basis for therapies to improve patient outcomes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:149-158, 2018.
老年骨折比年轻患者的骨折愈合时间更长，且愈合过程中并发症更多；然而，这种愈合差异的机制基础尚未得到很好的理解。为了增进对这一问题的理解，我们利用基因表达的高通量分析方法，研究了5个月大（年轻成年）和25个月大（老年）小鼠骨折愈合过程中的细胞和分子差异。小鼠接受双侧胫骨骨折，并在骨折后第5、10和20天（DPF）采集骨折痂进行分析。使用Affymetrix MoGene 1.0 ST微阵列进行全基因组表达分析。标准化后，使用方差分析比较数据，并使用主成分分析（PCA）、CTen、热图和Incromaps分析进行评估。PCA和横断面热图分析表明，DPF其次是年龄对基因表达变化有显著影响。未骨折和20 DPF的老年小鼠均显示免疫相关基因（CXCL8、CCL8和CCL5）表达增加，而在10 DPF时，老年小鼠显示基质相关基因（Matn1、Ucma、Scube1、Col9a1和Col9a3）表达增加。CTen分析表明，老年小鼠相对于年轻成年小鼠，CD8+细胞和巨噬细胞富集，相反，年轻成年小鼠相对于老年小鼠肥大细胞的患病率更高。最后，与PCA数据一致，BMP、印度刺猬、Notch和Wnt等经典骨愈合途径首先根据骨折后时间聚类，其次是年龄。
对愈合过程中年龄依赖性分子变化的更深入理解将有助于形成改善患者预后治疗的机制基础。©2017骨科学研究协会。由Wiley Periodicals, Inc.出版。《矫形外科学研究》36:149 - 158，2018年。
