LIGHT SHEET FLUORESCENCE MICROSCOPY (LSFM): A NOVEL TOOL FOR 3D OPTICAL RECONSTRUCTIONS OF MOUSE ARTERIOVENOUS FISTULAE IN CONTROL AND UREMIC ANIMALS

Introduction:

The arteriovenous fistula (AVF) is currently the gold standard for dialysis vascular access. Unfortunately over 50% of AVFs fail to mature, most often as a result of a venous segment stenosis. We and others have hypothesized that this is likely due to two interactive upstream pathogenetic pathways (hemodynamic stress and uremic vascular biology) which then results in two interacting downstream pathological pathways (neointimal hyperplasia and inadequate outward remodeling) that result in a venous segment stenosis.To better elucidate the mechanisms involved in these processes, we have developed a novel approach termed Light Sheet Fluorescence Microscopy (LSFM), which can generate 3D optical reconstructions of AVF vessel architecture, with regard to volume, geometry, and the presence or absence of neointimal hyperplasia. The goal of this study was to describe the use of LSFM in normal and uremic animals.

Methods:

Uremia was induced in 16-week-old wild-type and uremic mice on a C57BL/6 background with a polectomy of the ipsilateral kidney on Day 0 followed by a a unilateral nephrectomy of the contralateral kidney on Day 7. End (jugular) to side (carotid) AVFs were then created 14 days after the nephrectomy. Animals were sacrificed at 21d post AVF creation and the AVF was harvested for LSFM (in some animals) and conventional histomorphometry (in other animals). 

Results:

Uremic mice had a decrease in the average (6 sections at 100 micron intervals across the venous segment) percentage luminal patency as compared to control animals on histomorphometric analysis (12±1.4% vs 36.1±11.5%, p<0.05) at 21 days post-surgery. Consistent with this data, the LSFM analysis documented that lesion volume within the venous segment was increased in the uremic mouse model (0.79 cubic mm versus 0.25 cubic mm) and the length of lesion was also doubled in the uremic mouse model (1mm vs 2mm); see Fig below.

Conclusions:

Our results suggest that LSFM could be a particularly useful tool for obtaining a holistic assessment of both 3D anatomy and stenosis across the entire venous segment as opposed to looking at discreet sections every 100-200 microns. While the latter is the current technical standard, it is unfortunately prone to miss short regions of maximal stenosis. 

Portions of this data would have been presented at ASN Kidney Week 2024

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.