Alcazar Cynthia A, Hu Caroline, Rando Thomas A, Huang Ngan F, Nakayama Karina H
Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, USA.
Biomater Sci. 2020 Oct 7;8(19):5376-5389. doi: 10.1039/d0bm00990c. Epub 2020 Sep 2.
The regeneration of skeletal muscle can be permanently impaired by traumatic injuries, despite the high regenerative capacity of native muscle. An attractive therapeutic approach for treating severe muscle inuries is the implantation of off-the-shelf engineered biomimetic scaffolds into the site of tissue damage to enhance muscle regeneration. Anisotropic nanofibrillar scaffolds provide spatial patterning cues to create organized myofibers, and growth factors such as insulin-like growth factor-1 (IGF-1) are potent inducers of both muscle regeneration as well as angiogenesis. The aim of this study was to test the therapeutic efficacy of anisotropic IGF-1-releasing collagen scaffolds combined with voluntary exercise for the treatment of acute volumetric muscle loss, with a focus on histomorphological effects. To enhance the angiogenic and regenerative potential of injured murine skeletal muscle, IGF-1-laden nanofibrillar scaffolds with aligned topography were fabricated using a shear-mediated extrusion approach, followed by growth factor adsorption. Individual scaffolds released a cumulative total of 1244 ng ± 153 ng of IGF-1 over the course of 21 days in vitro. To test the bioactivity of IGF-1-releasing scaffolds, the myotube formation capacity of murine myoblasts was quantified. On IGF-1-releasing scaffolds seeded with myoblasts, the resulting myotubes formed were 1.5-fold longer in length and contained 2-fold greater nuclei per myotube, when compared to scaffolds without IGF-1. When implanted into the ablated murine tibialis anterior muscle, the IGF-1-laden scaffolds, in conjunction with voluntary wheel running, significantly increased the density of perfused microvessels by greater than 3-fold, in comparison to treatment with scaffolds without IGF-1. Enhanced myogenesis was also observed in animals treated with the IGF-1-laden scaffolds combined with exercise, compared to control scaffolds transplanted into mice that did not receive exercise. Furthermore, the abundance of mature neuromuscular junctions was greater by approximately 2-fold in muscles treated with IGF-1-laden scaffolds, when paired with exercise, in comparison to the same treatment without exercise. These findings demonstrate that voluntary exercise improves the regenerative effect of growth factor-laden scaffolds by augmenting neurovascular regeneration, and have important translational implications in the design of off-the-shelf therapeutics for the treatment of traumatic muscle injury.
尽管天然肌肉具有很高的再生能力，但创伤性损伤仍可能永久性损害骨骼肌的再生。一种有吸引力的治疗严重肌肉损伤的方法是将现成的工程仿生支架植入组织损伤部位，以促进肌肉再生。各向异性纳米纤维支架提供空间图案线索以形成有组织的肌纤维，而胰岛素样生长因子-1（IGF-1）等生长因子是肌肉再生和血管生成的有效诱导剂。本研究的目的是测试各向异性释放IGF-1的胶原蛋白支架与自主运动相结合治疗急性体积性肌肉损失的疗效，重点关注组织形态学效应。为了增强受伤小鼠骨骼肌的血管生成和再生潜力，采用剪切介导的挤压方法制备了具有排列地形的负载IGF-1的纳米纤维支架，随后进行生长因子吸附。在体外21天的过程中，单个支架累计释放了1244 ng±153 ng的IGF-1。为了测试释放IGF-1的支架的生物活性，对小鼠成肌细胞形成肌管的能力进行了量化。与没有IGF-1的支架相比，在接种有成肌细胞的释放IGF-1的支架上形成的肌管长度长1.5倍，每个肌管含有的细胞核数量多2倍。当植入切除的小鼠胫前肌时，与使用没有IGF-1的支架治疗相比，负载IGF-1的支架与自主轮转运动相结合，使灌注微血管的密度显著增加了3倍以上。与移植到未接受运动的小鼠体内的对照支架相比，在接受负载IGF-1的支架联合运动治疗的动物中也观察到了增强的肌生成。此外，与不进行运动的相同治疗相比，在负载IGF-1的支架联合运动治疗的肌肉中，成熟神经肌肉接头的丰度大约高2倍。这些发现表明，自主运动通过增强神经血管再生来改善负载生长因子的支架的再生效果，并且在设计用于治疗创伤性肌肉损伤的现成疗法方面具有重要的转化意义。
