Fang Liang, Liu Zhongting, Wang Cuicui, Shi Meng, He Yonghua, Lu Aiwu, Li Xiaofei, Li Tiandao, Zhu Donghui, Zhang Bo, Guan Jianjun, Shen Jie
Department of Orthopaedic Surgery, School of Medicine, Washington University, St. Louis, MO, 63110, USA.
Department of Mechanical Engineering & Materials Sciences, School of Engineering, Washington University, St. Louis, MO, 63110, USA.
Bioact Mater. 2024 Jul 10;36:580-594. doi: 10.1016/j.bioactmat.2024.07.003. eCollection 2024 Jun.
Critical size bone defects represent a significant challenge worldwide, often leading to persistent pain and physical disability that profoundly impact patients' quality of life and mental well-being. To address the intricate and complex repair processes involved in these defects, we performed single-cell RNA sequencing and revealed notable shifts in cellular populations within regenerative tissue. Specifically, we observed a decrease in progenitor lineage cells and endothelial cells, coupled with an increase in fibrotic lineage cells and pro-inflammatory cells within regenerative tissue. Furthermore, our analysis of differentially expressed genes and associated signaling pathway at the single-cell level highlighted impaired angiogenesis as a central pathway in critical size bone defects, notably influenced by reduction of Spp1 and Cxcl12 expression. This deficiency was particularly pronounced in progenitor lineage cells and myeloid lineage cells, underscoring its significance in the regeneration process. In response to these findings, we developed an innovative approach to enhance bone regeneration in critical size bone defects. Our fabrication process involves the integration of electrospun PCL fibers with electrosprayed PLGA microspheres carrying Spp1 and Cxcl12. This design allows for the gradual release of Spp1 and Cxcl12 in vitro and in vivo. To evaluate the efficacy of our approach, we locally applied PCL scaffolds loaded with Spp1 and Cxcl12 in a murine model of critical size bone defects. Our results demonstrated restored angiogenesis, accelerated bone regeneration, alleviated pain responses and improved mobility in treated mice.
临界尺寸骨缺损在全球范围内都是一项重大挑战，常常导致持续疼痛和身体残疾，对患者的生活质量和心理健康产生深远影响。为了应对这些缺损所涉及的复杂修复过程，我们进行了单细胞RNA测序，并揭示了再生组织中细胞群体的显著变化。具体而言，我们观察到再生组织中祖细胞系细胞和内皮细胞减少，同时纤维化细胞系细胞和促炎细胞增加。此外，我们在单细胞水平对差异表达基因和相关信号通路的分析突出了血管生成受损是临界尺寸骨缺损的核心通路，尤其受到Spp1和Cxcl12表达降低的影响。这种缺陷在祖细胞系细胞和髓系细胞系细胞中尤为明显，凸显了其在再生过程中的重要性。针对这些发现，我们开发了一种创新方法来促进临界尺寸骨缺损的骨再生。我们的制造过程涉及将电纺PCL纤维与携带Spp1和Cxcl12的电喷雾PLGA微球相结合。这种设计允许Spp1和Cxcl12在体外和体内逐渐释放。为了评估我们方法的有效性，我们在临界尺寸骨缺损的小鼠模型中局部应用负载有Spp1和Cxcl12的PCL支架。我们的结果表明，治疗后的小鼠血管生成恢复、骨再生加速、疼痛反应减轻且活动能力改善。
