Geisse Nicholas A, Sheehy Sean P, Parker Kevin Kit
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
In Vitro Cell Dev Biol Anim. 2009 Jul-Aug;45(7):343-50. doi: 10.1007/s11626-009-9182-9. Epub 2009 Feb 28.
Tissue microenvironments can regulate cell behavior by imposing physical restrictions on their geometry and size. An example of these phenomena is cardiac morphogenesis, where morphometric changes in the heart are concurrent with changes in the size, shape, and cytoskeleton of ventricular myocytes. In this study, we asked how myocytes adapt their size, shape, and intracellular architecture when spatially confined in vitro. To answer this question, we used microcontact printing to physically constrain neonatal rat ventricular myocytes on fibronectin islands in culture. The myocytes spread and assumed the shape of the islands and reorganized their cytoskeleton in response to the geometric cues in the extracellular matrix. Cytoskeletal architecture is variable, where myocytes cultured on rectangular islands of lower aspect ratios (length to width ratio) were observed to assemble a multiaxial myofibrillar arrangement; myocytes cultured on rectangles of aspect ratios approaching those observed in vivo had a uniaxial orientation of their myofibrils. Using confocal and atomic force microscopy, we made precise measurements of myocyte volume over a range of cell shapes with approximately equal surface areas. When myocytes are cultured on islands of variable shape but the same surface area, their size is conserved despite the changes in cytoskeletal architecture. Our data suggest that the internal cytoskeletal architecture of the cell is dependent on extracellular boundary conditions while overall cell size is not, suggesting a growth control mechanism independent of the cytoskeleton and cell geometry.
组织微环境可通过对细胞的几何形状和大小施加物理限制来调节细胞行为。这些现象的一个例子是心脏形态发生,其中心脏的形态测量变化与心室肌细胞的大小、形状和细胞骨架的变化同时发生。在本研究中,我们探讨了体外空间受限的情况下,心肌细胞如何调整其大小、形状和细胞内结构。为了回答这个问题,我们使用微接触印刷技术在培养的纤连蛋白岛状物上对新生大鼠心室肌细胞进行物理限制。心肌细胞铺展并呈现岛状物的形状,并根据细胞外基质中的几何线索重组其细胞骨架。细胞骨架结构是可变的,观察到在长宽比更低的矩形岛状物上培养的心肌细胞组装成多轴肌原纤维排列;在长宽比接近体内观察到的矩形上培养的心肌细胞其肌原纤维呈单轴排列。使用共聚焦显微镜和原子力显微镜,我们在一系列表面积大致相等的细胞形状范围内对心肌细胞体积进行了精确测量。当心肌细胞在形状可变但表面积相同的岛状物上培养时,尽管细胞骨架结构发生了变化,但其大小保持不变。我们的数据表明,细胞的内部细胞骨架结构依赖于细胞外边界条件,而细胞的整体大小则不然,这表明存在一种独立于细胞骨架和细胞几何形状的生长控制机制。