Extension of SALS to transmural quantitative structural analysis of planar tissues : Functional Imaging and Optical Manipulation of Living Cells

Introduction: Planar fibrous connective tissues are composed of a dense extra-cellular network of collagen and elastin fibers embedded in a ground matrix. Thus, quantification of fiber architecture an important step in developing an understanding of the mechanics of planar tissues. We have extensively used small angle light scattering (SALS) to map the gross fiber orientation of several soft membrane connective tissues using a custom built high speed mapping instrument. However, the current technique is limited to total through-thickness tissue structural analysis. The current study was undertaken to determine the feasibility of obtaining transmural tissue structural information from 2D SALS data. Methods: The basic approach is to utilize precisely aligned serial histological sections cut en-face through a tissue block and obtain 2D fiber structure from each section using SALS. Transmural fiber structure information is then derived by integration of 2D data to form a single data set containing the complete transmural fiber structure. To demonstrate the feasibility of the method, both explanted bioprosthetic heart valve (BHV) and native bovine pericardium (BP) tissues were evaluated. Results: The transmural SALS technique revealed for explanted BHV preferential damage in the fibrosa layer, while for BP variations in transmural fiber architecture were found consistent with optical histology. Conclusions: The transmural SALS technique successfully demonstrated quantitative transmural variations in fiber architecture in two dense collagenous tissues in a rapid, cost-effective approach.