Analysis of Regional Variations of the Interstitial Cells of Cajal in the Murine Distal Stomach Informed by Confocal Imaging and Machine Learning Methods

Abstract

Introduction-The network of Interstitial Cells of Cajal (ICC) plays a plethora of key roles in maintaining, coordinating, and regulating the contractions of the gastrointestinal (GI) smooth muscles. Several GI functional motility disorders have been associated with ICC degradation. This study extended a previously reported 2D morphological analysis and applied it to 3D spatial quantification of three different types of ICC networks in the distal stomach guided by confocal imaging and machine learning methods. The characterization of the complex changes in spatial structure of the ICC network architecture contributes to our understanding of the roles that different types of ICC may play in postprandial physiology, pathogenesis, and/or amelioration of GI dsymotility-bridging structure and function. Methods-A validated classification method using Trainable Weka Segmentation was applied to segment the ICC from a confocal dataset of the gastric antrum of a transgenic mouse, followed by structural analysis of the segmented images. Results-The machine learning model performance was compared to manually segmented subfields, achieving an area under the receiver-operating characteristic (AUROC) of 0.973 and 0.995 for myenteric ICC (ICC-MP; n = 6) and intramuscular ICC (ICC-IM; n = 17). The myenteric layer in the distal antrum increased in thickness (from 14.5 to 34 lm) towards the lesser curvature, whereas the thickness decreased towards the lesser curvature in the proximal antrum (17.7 to 9 lm). There was an increase in ICC-MP volume from proximal to distal antrum (406,960 ± 140,040 vs. 559,990 ± 281,000 lm 3 ; p = 0.000145). The % of ICC volume was similar for ICC-LM and for ICC-CM between proximal (3.6 ± 2.3% vs. 3.1 ± 1.2%; p = 0.185) and distal antrum (3.2 ± 3.9% vs. 2.5 ± 2.8%; p = 0.309). The aver-age % volume of ICC-MP was significantly higher than ICC-IM at all points throughout sample (p < 0.0001). Conclusions-The segmentation and analysis methods provide a high-throughput framework of investigating the structural changes in extended ICC networks and their associated physiological functions in animal models.

Unravelling the Three-Dimensional Structure-Function Relationships of Interstitial Cells of Cajal Networks: A Graph Theoretical Approach to Neurogastroenterology

“…While for the distal antrum, the shift is by 71.53°; with ICC-LM (𝜑𝜑 = 163.64°, 𝜃𝜃 = 0.90°) and ICC-CM (𝜑𝜑 = 92.11°, 𝜃𝜃 = 5.02°). The observations in this study is in good agreement with the previous study 37 , which reported the orientation of ICC-LM networks relative to ICC-CM to be 92.43 ± 18.17° in the proximal and 83.98 ± 14.54° in the distal antrum. Although the outer longitudinal coat and inner circular muscle bundles of the stomach were assumed to be orthogonal 41 , the findings presented here shows that it is possible that networks of ICC-LM and ICC-CM are not perfectly perpendicular.…”

“…Nonetheless, it is important to note that the efficiency for active SW propagation within the networks of ICC does not only depend on the mean connectivity path length, but also the overall structure and function of the network e.g., network density, volume 37 , diameter, alignment and orientation. The diameter metric formulated in this study by the application of 3D Euclidean distance transform, measures the width of 3D cellular structures in the ICC network, which may be among the contributing factors affecting SW propagation through the network.…”

“…Additionally, it should be able to handle fluctuations in image contrast and preserve the topology of the underlying data 16 . The issues with fluctuating SNRs and uneven illumination of ICC networks have been dealt with through the pre-processing steps of binarizing the image data using a supervised ML classification approach 36,37 .…”

Neural regulation of slow waves and phasic contractions in the distal stomach: a mathematical model

“…Furthermore, the intricate structural arrangements and biophysical relationships of different cell sub-classes of ICC and PDGFRα + cells would need to be considered across extended spatial scales. This is a challenging task that requires sophisticated whole-mount imaging of transgenic animals or specific labelling of ICC sub-types accompanied by investigations of specific channels and channel control mechanisms [62].…”

Functional and anatomical gastric regions and their relations to motility control

“…Disorders of gastric function that are common, but often poorly treated by available therapies, include the related conditions, gastroparesis and functional dyspepsia 1,2 . In response to the shortcomings of current treatments and difficulties in determining underlying causes of these disorders, as well as other disorders such as achalasia, gastric ileus and gastro‐esophageal reflux disease, a range of animal models have been used and, in addition, there has been recent development of computer‐based models and simulations of gastric function 3–7 . Although adequate modeling requires accurate, quantitative integration of knowledge of anatomy and function, this knowledge is not always used or readily accessible.…”