Journal of Biomechanics, Jan 3, 2012, Vol.45(1), p.107(9)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jbiomech.2011.09.015 Byline: Tiina Roose (a), Melody A. Swartz (b) Keywords: Interstitial flow; Tissue fluid balance; Darcy flow; Tissue architecture; Capillary Abstract: Lymphatic capillary drainage of interstitial fluid under both steady-state and inflammatory conditions is important for tissue fluid balance, cancer metastasis, and immunity. Lymphatic drainage function is critically coupled to the fluid mechanical properties of the interstitium, yet this coupling is poorly understood. Here we sought to effectively model the lymphatic-interstitial fluid coupling and ask why the lymphatic capillary network often appears with roughly a hexagonal architecture. We use homogenization method, which allows tissue-scale lymph flow to be integrated with the microstructural details of the lymphatic capillaries, thus gaining insight into the functionality of lymphatic anatomy. We first describe flow in lymphatic capillaries using the Navier-Stokes equations and flow through the interstitium using Darcy's law. We then use multiscale homogenization to derive macroscale equations describing lymphatic drainage, with the mouse tail skin as a basis. We find that the limiting resistance for fluid drainage is that from the interstitium into the capillaries rather than within the capillaries. We also find that between hexagonal, square, and parallel tube configurations of lymphatic capillary networks, the hexagonal structure is the most efficient architecture for coupled interstitial and capillary fluid transport; that is, it clears the most interstitial fluid for a given network density and baseline interstitial fluid pressure. Thus, using homogenization theory, one can assess how vessel microstructure influences the macroscale fluid drainage by the lymphatics and demonstrate why the hexagonal network of dermal lymphatic capillaries is optimal for interstitial tissue fluid clearance. Author Affiliation: (a) Bioengineering Group, School of Engineering Sciences, University Road, University of Southampton, SO17 1BJ, United Kingdom (b) Institute of Bioengineering and Swiss Institute for Experimental Cancer Research (ISREC), Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne, Switzerland Article History: Accepted 28 September 2011
Skin -- Analysis ; Skin -- Mechanical Properties ; Skin -- Models ; Cancer Metastasis -- Analysis ; Cancer Metastasis -- Mechanical Properties ; Cancer Metastasis -- Models ; Permeability -- Analysis ; Permeability -- Mechanical Properties ; Permeability -- Models
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