新型3D组织工程化肌肉衰减综合征模型的建立

Sarcopenia is an age-associated progressive decline in skeletal muscle mass and strength that is widely prevalent in developed nations and ageing societies. It is often associated with obesity, falling and deadly hip fractures. However, the molecular and cellular mechanisms of sarcopenia are not yet completely understood. As a result, no drugs have been approved for the treatment of sarcopenia. One of the key reasons for this lack in progress is that the skeletal muscle physiology and metabolism in mice are significantly different from humans. Therefore, to fully understand the molecular mechanisms underlying sarcopenia and develop treatments for it, it is necessary to develop accurate and effective models of the human condition. To achieve this goal, we need to construct 3D bioengineered human muscles, or a mini muscle organoid, that truly mimics the physiological structure and function of human muscles in vivo, and how they respond to chronic inflammation to manifest the loss of muscle mass and accumulation of fat during sarcopenia. In our current study, we aim to construct a 3D human vascularized-skeletal muscle model, followed by exposure to patient serum or a comprehensive mixture of inflammatory proteins to induce sarcopenia. The model will be used to reveal the molecular mechanisms of sarcopenia associated with inflammatory cytokines, and to seek an effective approach for the intervention and treatment of sarcopenia.

肌肉衰减综合征普遍存在于高龄人群，它是导致老年人肌肉质量、力量下降，引起肥胖、跌倒和骨折的重要原因。然而，肌肉衰减综合征的发病机制尚不明确，更无法有效地干预与治疗。其中，最大的障碍是小鼠模型与人在肌肉生理、代谢方面存在巨大差异，大多数运用小鼠模型获得的研究结论并不准确。因此，为了充分理解肌肉衰减的分子机制和研发治疗新策略，迫切需要建立有效的人肌肉衰减模型。为了达到这一目标，有必要建立人的3D工程化仿生肌肉。这些 “迷你肌肉”可以更真实地模拟人体肌肉生理结构和功能，以及响应慢性炎症并表现出肌肉质量丢失和脂肪积累的肌肉衰减综合征的特征。本研究旨在通过建立人3D血管化骨骼肌，并使用多个炎症因子蛋白联合或肌肉衰减病人血清诱导，建立人类3D肌肉衰减综合征模型。此模型为揭示肌肉衰减综合征的分子机制，药物筛选、药物毒性评价，提出有效的干预治疗策略提供重要的理论指导和实验平台。

由于小鼠模型与人在肌肉生理、代谢方面存在巨大差异，大多数运用小鼠模型开发的治疗肌肉衰减综合征药物在临床阶段失败。为此我们建立人的3D工程化仿生肌肉用于筛选促进肌肉肥厚的药物。首先，通过激活Wnt/BMP/FGF信号和生长因子诱导，胚胎干细胞H1被诱导分化为肌肉干细胞H1C和肌管。这些肌肉干细胞可以大量扩增并表达肌肉干细胞特异标志物。其次，胚胎干细胞来源的内皮细胞和原代HUVECs，分别与肌肉干细胞（1：1或1：3）混合培养，成功建立人3D血管化肌肉模型，分别表达标志物CD31和MF20。再次，高代数的肌肉干细胞分化的肌管表现为atrophy，可以用于建立人3D血管化肌肉衰减模型。最后，人3D（血管化）肌肉模型可以用于评估药物毒性；同时，我们筛选到促进肌肉肥厚的候选药物D+E+F，D+E+F增加MHC蛋白表达、上调肌肉分化成熟及收缩基因的表达、twitch force最强。此模型可以准确评价药物毒性作用、药效（肥厚表型和运动功能）。在未来，3D(血管化)人肌肉模型有望应用于创伤后肌肉再生和修复。