CLEARING UP INCONTINENCE: DEVELOPING OPTICAL TISSUE CLEARING TECHNIQUES TO UNRAVEL THE 3D NEUROANATOMY OF BLADDER CONTROL IN THE HUMAN SPINAL CORD

In our aging population, urinary incontinence is a prevalent and growing problem with a significant impact on patients’ quality of life. Onuf’s nucleus, a small cell group in the sacral spinal cord (SSC), plays a key role in regulating bladder control. However, little is known about its micro-anatomy or cell composition. This is largely due to the fact that this nucleus spreads across several millimeters along the length of the SSC as well as multiple segments, making it challenging to image with traditional (2D) histology methods. Improved understanding of the neuroanatomy of Onuf’s nucleus and the SSC is essential to improve our understanding of bladder control and therapeutic options from patients with urinary incontinence. Leveraging innovative 3D histology techniques to overcome current methodological limitations, we demonstrate a) the development and application of new optical tissue clearing protocols for human spinal cord (Fig. 1) in order to b) improve our neuroanatomical understanding of SSC nuclei such as Onuf’s nucleus and their role in bladder control.

Figure 1: 3D histology of Onuf's nucleus in the human SSC. a) ecoMASH allows efficient clearing of highly myelinated, formalin-fixed human SSC samples while using less hazardous chemicals than other solvent-based approaches (grid: large squares = 1x1 cm). b) 2D plane of Nissl-stained 3D data with Onuf's nucleus highlighted in orange. c) and d) 3D rendering of dataset (greyscale) with segmented grey matter outline in purple and Onuf's nucleus segmentation in cyan (both in d).