McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Orthofix Medical, Inc., Lewisville, Texas, USA.
J Orthop Res. 2022 Jul;40(7):1593-1603. doi: 10.1002/jor.25185. Epub 2021 Oct 17.
Rotator cuff repair failure remains common due to poor tendon healing, particularly at the enthesis. We previously showed that pulsed electromagnetic field (PEMF) therapy improved the mechanical properties of the rat supraspinatus tendon postoperatively. However, little is known about the mechanisms behind PEMF-dependent contributions to improved healing in this injury model. The objective of this study was to determine the influence of PEMF treatment on tendon gene expression and cell composition, as well as bone microarchitecture and dynamic bone metabolism during early stages of healing. We hypothesized that PEMF treatment would amplify tendon-healing related signaling pathways while mitigating inflammation and improve bone metabolism at the repair site. Rats underwent rotator cuff injury and repair followed by assignment to either control (non-PEMF) or PEMF treatment groups. Gene and protein expression as well as tendon and bone histological assessments were performed 3, 7, 14, 21, and 28 days after injury. Gene expression data demonstrated an upregulation in the bone morphogenetic protein 2 signaling pathway and increases in pro-osteogenic genes at the insertion, supporting important processes to re-establish the tendon-bone interface. PEMF also downregulated genes related to a fibrotic healing response. Anti-inflammatory effects were demonstrated by both gene expression and macrophage phenotype. PEMF significantly increased the rate of kinetic bone formation directly adjacent to the tendon enthesis as well as the number of cuboidal surface osteoblasts (active osteoblasts) in the humeral head. This study has provided insight into how PEMF affects cellular and molecular processes in the supraspinatus tendon and adjacent bone after injury and repair.
肩袖修复失败仍然很常见，这是由于肌腱愈合不良，特别是在肌腱止点处。我们之前的研究表明，脉冲电磁场（PEMF）治疗可以改善术后大鼠冈上肌腱的力学性能。然而，对于 PEMF 依赖的这种损伤模型愈合改善的机制知之甚少。本研究的目的是确定 PEMF 治疗对肌腱基因表达和细胞组成的影响，以及在愈合早期对修复部位骨微结构和动态骨代谢的影响。我们假设 PEMF 治疗会放大与肌腱愈合相关的信号通路，同时减轻炎症，并改善修复部位的骨代谢。大鼠接受肩袖损伤和修复，然后分为对照组（非 PEMF）或 PEMF 治疗组。在损伤后 3、7、14、21 和 28 天进行基因和蛋白质表达以及肌腱和骨组织学评估。基因表达数据显示骨形态发生蛋白 2 信号通路上调，插入处的前成骨基因增加，这支持了重新建立肌腱-骨界面的重要过程。PEMF 还下调了与纤维化愈合反应相关的基因。基因表达和巨噬细胞表型均显示出抗炎作用。PEMF 显著增加了与肌腱止点直接相邻的骨的动力学形成率，以及肱骨头中立方表面成骨细胞（活跃成骨细胞）的数量。这项研究深入了解了 PEMF 如何影响损伤和修复后冈上肌腱和相邻骨中的细胞和分子过程。
