Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
Stanford Cardiovascular Institute and Department of Medicine, Stanford University, Stanford, California, USA.
FASEB J. 2022 Aug;36(8):e22453. doi: 10.1096/fj.202200500R.
Constructing engineered human skeletal muscle tissues that resemble the function and microstructure of human skeletal muscles is key to utilizing them in a variety of applications such as drug development, disease modeling, regenerative medicine, and engineering biological machines. However, current in vitro skeletal muscle tissues are far inferior to native muscles in terms of contractile function and lack essential cues for muscle functions, particularly heterotypic cell-cell interactions between myoblasts, endothelial cells, and fibroblasts. Here, we develop an engineered muscle tissue with a coaxial three-layered tubular structure composed of an inner endothelial cell layer, an endomysium-like layer with fibroblasts in the middle, and an outer skeletal muscle cell layer, similar to the architecture of native skeletal muscles. Engineered skeletal muscle tissues with three spatially organized cell types produced thicker myotubes and lowered Young's modulus through extracellular matrix remodeling, resulting in 43% stronger contractile force. Furthermore, we demonstrated that fibroblasts localized in the endomysium layer induced angiogenic sprouting of endothelial cells into the muscle layer more effectively than fibroblasts homogeneously distributed in the muscle layer. This layered tri-culture system enables a structured spatial configuration of the three main cell types of skeletal muscle and promotes desired paracrine signaling, resulting in improved angiogenesis and increased contractile force. This research offers new insights to efficiently obtain new human skeletal muscle models, transplantable tissues, and actuators for biological machines.
构建具有类似于人体骨骼肌功能和微观结构的工程化人类骨骼肌组织对于将其应用于各种领域至关重要，如药物开发、疾病建模、再生医学和工程生物机器。然而，目前的体外骨骼肌组织在收缩功能方面远逊于天然肌肉，并且缺乏肌肉功能的基本线索，特别是成肌细胞、内皮细胞和成纤维细胞之间的异质细胞-细胞相互作用。在这里，我们开发了一种具有同轴三层管状结构的工程化肌肉组织，由内层内皮细胞、中间的类肌内膜层和外层骨骼肌细胞层组成，类似于天然骨骼肌的结构。具有三种空间组织细胞类型的工程化骨骼肌组织通过细胞外基质重塑产生更厚的肌管并降低杨氏模量，从而使收缩力提高 43%。此外，我们证明了定位于肌内膜层的成纤维细胞比均匀分布在肌肉层中的成纤维细胞更有效地诱导内皮细胞向肌肉层中的血管生成发芽。这种分层三培养系统能够实现骨骼肌三种主要细胞类型的结构化空间配置，并促进所需的旁分泌信号传递，从而改善血管生成和增加收缩力。这项研究为有效获得新的人体骨骼肌模型、可移植组织和生物机器的致动器提供了新的见解。
