Regeneration of skeletal muscle after volumetric injury is thought to be impaired by a dysregulated immune microenvironment that hinders endogenous repair mechanisms. Such defects result in fatty infiltration, tissue scarring, chronic inflammation, and debilitating functional deficits. Here, we evaluated the key cellular processes driving dysregulation in the injury niche through localized modulation of sphingosine‐1‐phosphate (S1P) receptor signaling. We employ dimensionality reduction and pseudotime analysis on single cell cytometry data to reveal heterogeneous immune cell subsets infiltrating preclinical muscle defects due to S1P receptor inhibition. We show that global knockout of S1P receptor 3 (S1PR3) is marked by an increase of muscle stem cells within injured tissue, a reduction in classically activated relative to alternatively activated macrophages, and increased bridging of regenerating myofibers across the defect. We found that local S1PR3 antagonism via nanofiber delivery of VPC01091 replicated key features of pseudotime immune cell recruitment dynamics and enhanced regeneration characteristic of global S1PR3 knockout. Our results indicate that local S1P receptor modulation may provide an effective immunotherapy for promoting a proreparative environment leading to improved regeneration following muscle injury.

中文翻译：

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调节局部 S1P 受体信号作为体积性肌肉损失损伤后的再生免疫疗法


体积损伤后骨骼肌的再生被认为受到阻碍内源性修复机制的失调的免疫微环境的损害。这些缺陷会导致脂肪浸润、组织疤痕、慢性炎症和使人衰弱的功能缺陷。在这里，我们通过局部调节 1-磷酸鞘氨醇 (S1P) 受体信号传导来评估驱动损伤生态位失调的关键细胞过程。我们对单细胞细胞计数数据采用降维和伪时间分析，以揭示由于 S1P 受体抑制而浸润临床前肌肉缺陷的异质免疫细胞亚群。我们发现，S1P 受体 3 (S1PR3) 的整体敲除的特点是受损组织内肌肉干细胞的增加、经典激活的巨噬细胞相对于替代激活的巨噬细胞的减少以及跨缺陷的再生肌纤维的桥接增加。我们发现，通过纳米纤维递送 VPC01091 的局部 S1PR3 拮抗作用复制了伪时间免疫细胞招募动力学的关键特征，并增强了全局 S1PR3 敲除的再生特征。我们的结果表明，局部 S1P 受体调节可能提供有效的免疫疗法，以促进预修复环境，从而改善肌肉损伤后的再生。