Acellular composite hydrogel scaffolds for volumetric muscle regeneration

项目摘要 由于创伤、癌症等原因，每年有近500万例重建手术。 消融、整容手术或战斗伤害。破坏或移走大量的骨骼 肌肉，称为容积性肌肉损失(VML)，由车祸或战斗等创伤性事件引起 受伤，是一个重大的健康问题。骨骼肌高度血管化，依赖于足够的 血管的渗透修复和再生。VML修复的黄金标准是自体移植， 并受到功能结果降低和宿主介导的移植物血运重建不足的限制。当前 以生物材料为基础的组织工程方法修复VML依赖后骨骼肌组织 来自宿主的被动新生血管，而不是主动招募血管网络伴随 修复过程中卫星细胞的渗入。因此，仍然有很大的需要开发出能够 积极刺激血管系统的发展，以引导有组织和对齐的骨骼肌组织 再生。我们假设刺激新血管系统快速生成和排列的支架 肌肉组织将显著促进VML损伤的骨骼肌修复。为了检验这一假设，我们将 创造一类可生物降解的复合支架，将其植入VML损伤处，以使 内皮细胞和卫星细胞的募集。因此，目标是创造一种复合材料， 促进成熟的功能性肌肉组织的原位再生。为了制作这些支架，胶原海绵 有了定义的，各向异性结构将被制造并嵌入血管生成自组装肽 水凝胶，称为Slan(目标1)。支架力学的评估将补充体外分析 确定材料参数的细胞渗透和相容性，以诱导成对的血管化骨骼 肌肉组织。然后将由胶原、Slan或复合材料组成的支架植入小鼠模型 评估每种材料对加强VML修复的贡献(目标2)。特别强调的是 放置在这些支架支持功能恢复的能力上，通过肌肉收缩来衡量 纵向研究。组织学评估将表征：1)细胞的浸润性和对 定向支架引导骨骼肌组织有序生长，II)原位新生血管的调控 和支持结构，以及iii)炎症的变化。最终，我们的目标是解决两个主要限制 在骨骼肌组织再生方面：i)原位结构的血管形成不足，以及ii)缺乏 VML损伤修复过程中新生肌纤维的有组织排列；这两个已知因素抑制功能性 恢复。这些成果将导致一种新的复合材料类别的产生，以功能驱动 用水凝胶进行细胞渗透，这种凝胶是专门设计来招募必要的特定支持结构的 用于组织再生和修复。

Project Summary There are almost 5 million reconstructive procedures performed annually as a result of traumatic injury, cancer ablation, cosmetic procedures, or combat injuries. The destruction or removal of large amounts of skeletal muscle, termed volumetric muscle loss (VML), resulting from traumatic events such as car crashes or combat injuries, represents a significant health concern. Skeletal muscle is highly vascularized, and relies on adequate infiltration of blood vessels to repair and regenerate. The gold standard for VML repair is autologous grafting, and is limited by reduced functional outcomes and inadequate host-mediated graft revascularization. Current biomaterial-based tissue engineered approaches towards the repair of skeletal muscle tissue after VML rely on passive neovascularization from the host, as opposed to actively recruiting vascular networks to accompany satellite cell infiltration during repair. As such, there remains a significant need to develop materials that will actively stimulate the development of vasculature that will guide organized and aligned skeletal muscle tissue regeneration. We hypothesize that scaffolds that stimulate the rapid creation of a new vasculature and aligned muscle tissue will significantly enhance skeletal muscle repair in VML injuries. To test this hypothesis, we will create a class of biodegradable composite scaffolds that will be implanted into VML injuries to enable the recruitment of endothelial cells and satellite cells. As such, the objective is to create a composite material that promotes in situ regeneration of mature functional muscle tissue. To fabricate these scaffolds, collagen sponges with defined, anisotropic architectures will be fabricated and embedded with angiogenic self-assembling peptide hydrogels, termed SLan (Aim 1). Assessment of the mechanics of scaffolds will complement in vitro analyses of cellular infiltration and compatibility to define material parameters that will induce aligned vascularized skeletal muscle tissue. Scaffolds comprised of collagen, SLan, or composites will then be implanted into a murine model of VML to assess the contribution of each material to enhance VML repair (Aim 2). Particular emphasis will be placed on the ability of these scaffolds to support functional recovery as measured by muscular contraction in longitudinal studies. Histologic assessments will characterize i) the cellular infiltrate and the contribution of aligned scaffolds to guide organized skeletal muscle tissue growth, ii) the modulation of in situ neovascularization and supporting structures, and iii) changes in inflammation. Ultimately, we aim to address two major limitations within skeletal muscle tissue regeneration: i) inadequate vascularization of constructs in situ, and ii) the lack of organized alignment of nascent myofibers during repair of VML injuries; both factors known to inhibit functional recovery. These outcomes will result in the creation of a new class of composite materials to functionally drive cellular infiltration with hydrogels that are specifically designed to recruit specific supporting structures necessary for tissue regeneration and repair.