Sniekers Y H, van Donkelaar C C
Department of Biomedical Engineering, Eindhoven University of Technology, The Netherlands.
Biophys J. 2005 Aug;89(2):1302-7. doi: 10.1529/biophysj.104.053652. Epub 2005 May 13.
Diffusion plays an important role in the transport of nutrients and signaling molecules in cartilaginous tissues. Diffusion coefficients can be measured by fluorescence recovery after photobleaching (FRAP). Available methods to analyze FRAP data, however, assume homogeneity in the environment of the bleached area and neglect geometrical restrictions to diffusion. Hence, diffusion coefficients in inhomogeneous materials, such as most biological tissues, cannot be assessed accurately. In this study, a new method for analyzing data from FRAP measurements has been developed, which is applicable to inhomogeneous tissues. It is based on a fitting procedure of the intensity recovery after photobleaching with a two-dimensional finite element analysis, which includes Fick's law for diffusion. The finite element analysis can account for distinctive diffusivity in predefined zones, which allows determining diffusion coefficients in inhomogeneous samples. The method is validated theoretically and experimentally in both homogeneous and inhomogeneous tissues and subsequently applied to the proliferation zone of the growth plate. Finally, the importance of accounting for inhomogeneities, for appropriate assessment of diffusivity in inhomogeneous tissues, is illustrated.
扩散在软骨组织中营养物质和信号分子的运输过程中起着重要作用。扩散系数可通过光漂白后荧光恢复(FRAP)来测量。然而,现有的分析FRAP数据的方法假定漂白区域环境是均匀的,并且忽略了扩散的几何限制。因此,对于非均匀材料(如大多数生物组织)中的扩散系数,无法进行准确评估。在本研究中,开发了一种新的分析FRAP测量数据的方法,该方法适用于非均匀组织。它基于用二维有限元分析对光漂白后强度恢复进行拟合的过程,其中包括扩散的菲克定律。有限元分析可以考虑预定义区域中独特的扩散率,这使得能够确定非均匀样品中的扩散系数。该方法在均匀和非均匀组织中均经过理论和实验验证,随后应用于生长板的增殖区。最后,说明了考虑非均匀性对于准确评估非均匀组织中扩散率的重要性。