Massive rotator cuff tears (MRCTs) of the shoulder cause disability and pain among the adult population. In chronic injuries, the tendon retraction and subsequently the loss of mechanical load lead to muscle atrophy, fat accumulation, and fibrosis formation over time. The intrinsic repair mechanism of muscle and the successful repair of the torn tendon cannot reverse the muscle degeneration following MRCTs. To address these limitations, we developed an electroconductive matrix by incorporating graphene nanoplatelets (GnPs) into aligned poly(l-lactic acid) (PLLA) nanofibers. This study aimed to understand 1) the effects of GnP matrices on muscle regeneration and inhibition of fat formation in vitro and 2) the ability of GnP matrices to reverse muscle degenerative changes in vivo following an MRCT. The GnP matrix significantly increased myotube formation, which can be attributed to enhanced intracellular calcium ions in myoblasts. Moreover, the GnP matrix suppressed adipogenesis in adipose-derived stem cells. These results supported the clinical effects of the GnP matrix on reducing fat accumulation and muscle atrophy. The histological evaluation showed the potential of the GnP matrix to reverse muscle atrophy, fat accumulation, and fibrosis in both supraspinatus and infraspinatus muscles at 24 and 32 wk after the chronic MRCTs of the rat shoulder. The pathological evaluation of internal organs confirmed the long-term biocompatibility of the GnP matrix. We found that reversing muscle degenerative changes improved the morphology and tensile properties of the tendon compared with current surgical techniques. The long-term biocompatibility and the ability of the GnP matrix to treat muscle degeneration are promising for the realization of MRCT healing and regeneration.

中文翻译：

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肩部慢性大面积肩袖撕裂的肌肉退化：使用石墨烯基质解决实际问题

肩部的大面积肩袖撕裂 (MRCT) 会导致成年人群中的残疾和疼痛。在慢性损伤中，随着时间的推移，肌腱收缩和随后的机械负荷损失导致肌肉萎缩、脂肪堆积和纤维化形成。肌肉的内在修复机制和肌腱撕裂的成功修复不能逆转 MRCT 后的肌肉退化。为了解决这些限制，我们通过将石墨烯纳米片 (GnP) 结合到对齐的聚 (l-乳酸) (PLLA) 纳米纤维中开发了一种导电矩阵。本研究旨在了解 1) GnP 基质对体外肌肉再生和脂肪形成抑制的影响，以及 2) GnP 基质在 MRCT 后逆转体内肌肉退行性变化的能力。GnP 基质显着增加了肌管形成，这可归因于成肌细胞中增强的细胞内钙离子。此外，GnP 基质抑制脂肪来源的干细胞中的脂肪形成。这些结果支持 GnP 基质在减少脂肪堆积和肌肉萎缩方面的临床效果。组织学评估显示，在大鼠肩部慢性 MRCT 后 24 周和 32 周，GnP 基质具有逆转冈上肌和冈下肌肌肉萎缩、脂肪堆积和纤维化的潜力。内脏器官的病理学评估证实了 GnP 基质的长期生物相容性。我们发现，与目前的手术技术相比，逆转肌肉退行性变化改善了肌腱的形态和拉伸特性。