In recent years there has been substantial progress in terms of our understanding of the extracellular matrix (ECM) as not just a structural support but a critical regulator of cellular function and organ homeostasis. Many chronic diseases are characterised by dysregulation of the ECM, and this is especially true in the lung. Most studies to date have relied on thin tissue sections which only provide a tiny snapshot into what is happening in the organ as a whole. Large volume imaging will allow us to better understand how the ECM is organised and how this becomes dysregulated which is essential to gain a more complete understanding of the progression of disease.
We recently developed a protocol to clear large tissue sections that provided improved structural preservation of fragile tissue while allowing for visualisation of elastin and collagen through two photon excitation and second harmonic generation (SHG) respectively. However, this methodology suffered from incomplete clearing in dense ECM rich regions of diseased lung, weak SHG signal, and severe distortion of the point spread function at depth degrading image quality. After further optimisation we have been able to achieve consistent uniform clearing over tissue slices spanning 2x2x0.3cm even in severely disease affected regions, with good SHG, and clean images at depth. Using this optimised methodology, we have been identified important features in a number of lung diseases that have not been previously reported in the literature.
The University of Sydney