Numerical metrics for automated quantification of interstitial cell of Cajal network structural properties

Abstract

Depletion of interstitial cells of Cajal (ICC) networks is known to occur in several gastrointestinal motility disorders. Although confocal microscopy can effectively image and visualize the spatial distribution of ICC networks, current descriptors of ICC depletion are limited to cell numbers and volume computations. Spatial changes in ICC network structural properties have not been quantified. Given that ICC generate electrical signals, the organization of a network may also affect physiology. In this study, six numerical metrics were formulated to automatically determine complex ICC network structural properties from confocal images: density, thickness, hole size, contact ratio, connectivity and anisotropy. These metrics were validated and applied in proof-of-concept studies to quantitatively determine jejunal ICC network changes in mouse models with decreased (5-HT 2B receptor knockout (KO)) and normal (Ano1 KO) ICC numbers, and during post-natal network maturation. Results revealed a novel remodelling phenomenon occurring during ICC depletion, namely a spatial rearrangement of ICC and the preferential longitudinal alignment. In the post-natal networks, an apparent pruning of the ICC network was demonstrated. The metrics developed here enabled the first detailed quantitative analyses of structural changes that may occur in ICC networks during depletion and development.

Developmental Changes in Postnatal Murine Intestinal Interstitial Cell of Cajal Network Structure and Function

“…In particular, we wanted to test the presence of a pruning-like mechanism occurring in postnatal ICC network development 9 , similar to that observed in the CNS 19-21 . Understanding this early postnatal developmental process is important because impaired ICC development has been associated with several early postnatal GI disorders, including transient neonatal pseudo-obstruction 13 and infantile hypertrophic pyloric stenosis 35 .…”

“…This imaging data was then pre-processed to remove artifacts for the application of the ICC network structural metrics 9 . Briefly, small gaps with radius of 2 pixels (≈0.8 μm) or less in the network structure were joined, and small objects of less than 4 pixels (≈0.65 μm 2 ) were removed.…”

“…Four numerical metrics we recently proposed 9 were used to quantify the structural changes that occur in ICC-MP networks throughout postnatal development: Density : measures the ICC network volume, representative of the amount of bioelectrical current generated and propagated; Thickness : measures the width of cellular structures within the ICC network plane, which may impact electrical activity propagation through the network; Hole size : measures the radius of non-ICC regions within the ICC network plane. Reflects the distribution of ICC throughout the MP ( i.e., the ‘tightness’ of the network), and may relate to the uniformity of smooth muscle cell (SMC) activation;…”

“…Similar to these concepts, we recently proposed a potential pruning-like mechanism that occurs in postnatal ICC network development by comparing 3-day-and 4-week-old murine intestinal ICC-MP networks 9 . This study therefore aimed to identify, quantify, and characterize structural changes in ICC network imaging data acquired at multiple ages throughout early postnatal life to test the presence of a pruning-like mechanism, and to elucidate the temporal course of this process.…”

A Multiscale Tridomain Model for Simulating Bioelectric Gastric Pacing

“…However, in intact in-vivo tissue, ICC are entrained to a single frequency corresponding to the highest frequency present, which is critical for a coordinated motility of the GI tract [1], [4]. Depletion and degradation of ICC networks has been implicated in gastric motility disorders such as gastroparesis and slow transit constipation [5]–[8]. …”