Larkin Lisa M, Calve Sarah, Kostrominova Tatiana Y, Arruda Ellen M
Department of Biomedical Engineering, Division of Geriatric Medicine, Muscle Mechanics Laboratory, University of Michigan, Ann Arbor, Michigan 48109, USA.
Tissue Eng. 2006 Nov;12(11):3149-58. doi: 10.1089/ten.2006.12.3149.
During muscle contraction, the integrity of the myotendinous junction (MTJ) is important for the transmission of force from muscle to tendon. We evaluated the contractile and structural characteristics of 3-dimensional (3-D) skeletal muscle constructs co-cultured with engineered self-organized tendon constructs (n = 4), or segments of adult (n = 4) or fetal (n = 5) rat-tail tendon. We hypothesized that the co-culture of tendon and muscle would produce constructs with viable muscle-tendon interfaces that remain intact during generation of force. Construct diameter (lm) and maximum isometric force (microN) were measured, and specific force (kPa) was determined. After measure of force, constructs were loaded at a constant strain rate until failure and surface strains were recorded optically across the tendon, the muscle and the interface and used to determine the tangent modulus (passive stiffness) of the construct. Frozen samples were used for Trichrome Masson staining and immunofluorescent analysis of the MTJ-specific protein paxillin. No differences were observed between the groups with respect to diameter, maximum force, or specific force. The MTJ was robust and withstood tensile loading beyond the physiological strain range. The majority of the constructs failed in the muscle region. At the MTJ, there is an increase in the expression and localization of paxillin. In conclusion, using 3 sources of tendon tissue, we successfully engineered 3-D muscle-tendon constructs with functionally viable MTJ, characterized by structural features and protein expression patterns resembling neonatal MTJs in vivo.
在肌肉收缩过程中，肌腱连接点（MTJ）的完整性对于肌肉力量向肌腱的传递至关重要。我们评估了与工程化自组织肌腱构建体（n = 4）或成年大鼠（n = 4）或胎儿大鼠（n = 5）尾腱段共培养的三维（3-D）骨骼肌构建体的收缩和结构特征。我们假设肌腱和肌肉的共培养将产生具有可行的肌腱-肌肉界面的构建体，该界面在力的产生过程中保持完整。测量构建体直径（lm）和最大等长力（微牛顿），并确定比力（千帕）。在测量力之后，以恒定应变率加载构建体直至破坏，并通过光学方法记录整个肌腱、肌肉和界面的表面应变，并用于确定构建体的切线模量（被动刚度）。冷冻样本用于三色马森染色和MTJ特异性蛋白桩蛋白的免疫荧光分析。在直径、最大力或比力方面，各实验组之间未观察到差异。MTJ坚固，能够承受超出生理应变范围的拉伸载荷。大多数构建体在肌肉区域失效。在MTJ处，桩蛋白的表达和定位增加。总之，使用3种肌腱组织来源，我们成功构建了具有功能可行的MTJ的3-D肌腱-肌肉构建体，其结构特征和蛋白质表达模式类似于体内新生MTJ。
