Muscle stem cell therapy for volumetric muscle loss

严重的创伤会导致体积性肌肉丧失(VML)，导致终身残疾。虽然骨瘦如柴 肌肉具有显著的再生潜力，当损伤巨大并破坏潜在的肌肉时。 结构，再生被中止，取而代之的是疤痕组织的形成。《标准》 这种损伤的治疗是伤口闭合，功能恢复的希望微乎其微。再生的希望 医学是损伤组织的完全再生，要么通过促进内源性干细胞修复，要么通过促进 通过移植细胞来促进再生。也许这方面最好的例子是美国的皮肤移植 烧伤患者大量组织丢失的背景。移植皮肤含有内源性干细胞的事实 确保移植物不仅能迅速恢复功能，而且能长期恢复干细胞的功能 补充在组织正常周转过程中丢失的皮肤细胞。同样，长期目标是 再生医学是能够修复受损组织并在整个生命周期内保持该组织 个人的。 在肌肉干细胞(MuSCs)的培养和移植方面取得了重大进展 被称为“卫星细胞”)近几十年来，主要在啮齿动物的肌肉损伤和退行性病变模型中 疾病。40多年来，人们已经知道移植成肌细胞，更分化的后代 MUSCs，可以促进宿主的新肌肉形成。然而，人们很早就认识到，那些 细胞再生能力有限，无法形成新的干细胞。在我们正在进行的研究中，得到了 大量的初步数据，我们已经能够产生由脱细胞组成的“生物结构” 我们已经在水凝胶中植入了MSC的肌肉支架。当整个生物构造是 移植到小鼠后肢肌肉的VML病变中，我们目前能够实现有限的结构 和功能恢复。这一方案的研究重点是这项技术的发展 从而优化VML病变的MUSC治疗，并设计一种可扩展的治疗方法 人类。为了实现这一目标，我们概述了三个具体目标，每个目标都基于广泛的初步数据：1) 通过含有MUSC其他细胞成分的生殖性生物结构来加强MUSC的治疗 以促进MUSCs的植入和新生肌纤维的形成；2)优化 以自愿跑步或强制跑步机跑步的形式进行体力活动，以增强 MUSC治疗VML皮损；以及3)评估我们将我们的模型扩大10倍的能力 VML的大小和治疗使用两种不同的方法--直接缩放我们的生物结构和使用 “模块化”生物结构。 这项提议的总体目标是开发一种使用MUSC生物构建的可扩展技术 移植治疗VML。这将对退伍军人产生直接和直接的影响 患有骨骼肌损伤，这种损伤限制了他们的功能能力，到目前为止， 没有进一步康复的希望。我们的目标是开发一种新的肌肉组织修复治疗方法。 基于对基本干细胞生物学的深入了解，最新的干细胞生物学应用 解决这些临床挑战的生物工程方法，以及对临床/翻译的坚定承诺 改善功能和进一步康复受限退伍军人的健康和生活质量的使命 由于缺乏有效的治疗选择。

Major trauma can cause volumetric muscle loss (VML) resulting in life-long disability. Although skeletal muscle is capable of remarkable regenerative potential, when injury is massive and destroys the underlying architecture, regeneration is aborted and is characterized instead by scar tissue formation. The standard of care in such injuries is wound closure, leaving little hope for functional recovery. The promise of regenerative medicine is the full regeneration of damaged tissues, either by promoting repair from endogenous stem cells or by the transplantation of cells to enhance regeneration. Perhaps the best example of this is skin grafting in the setting of massive tissue loss in burn victims. The fact that grafted skin contains endogenous stem cells assures that the graft will not only restore function acutely but also chronically as the stem cells function to replenish skin cells that are lost during the normal turnover of the tissue. Likewise, the long-term goal of regenerative medicine is to be able to restore damaged tissue and maintain that tissue for the full lifetime of the individual. Major advances have been made in the culture and transplantation of muscle stem cells (MuSCs, also known as “satellite cells”) in recent decades, primarily in rodent models of muscle injury and degenerative disease. It has been known for over 40 years that transplanted myoblasts, the more differentiated progeny of MuSCs, can contribute to new muscle formation in the host. However, it has long been recognized that those cells have limited regenerative capacity and fail to form new stem cells. In our ongoing studies, supported by extensive Preliminary Data, we have been able to generate “bioconstructs” that consist of decellularized muscle scaffolds into which we have engrafted MuSCs in a hydrogel. When this whole bioconstruct is transplanted into a VML lesion in a mouse hindlimb muscle, we are currently able to achieve limited structural and functional restoration. The major focus of the studies of this proposal is the development of this technology so as to optimize MuSC treatment of VML lesions and to design a scalable therapy that could be translated to humans. Toward this goal, we have outlined three Specific Aims, each based on extensive Preliminary Data: 1) To enhance MuSC therapy by generative bioconstructs that contain other cellular components of the MuSC niche so as to improve the engraftment and de novo muscle fiber formation by the MuSCs; 2) To optimize the use of physical activity in the form of voluntary running or forced treadmill running to enhance the efficacy of MuSC treatment of VML lesions; and 3) To assess our ability to scale up our model using at 10-fold increase in VML size and treatment with two separate approaches – a direct scaling of our bioconstruct and the use of “modular” bioconstructs. The overall goal of this proposal is to develop a scalable technology using MuSC bioconstruct transplantation for the treatment of VML. This will have direct and immediate relevance to Veterans who are suffering from skeletal muscle injuries, injuries that have limited their functional capacity and that, to date, have had no hope of further recovery. Our goal is to develop a novel therapeutic approach to muscle tissue repair based upon a deep understanding of the basic stem cell biology, a state-of-the-art application of bioengineering approaches to these clinical challenges, and a firm commitment to the clinical/translational mission to improve the health and quality of life of Veterans whose function and further rehabilitation is limited by the lack of effective therapeutic options.