APRIL 2024 VOLUME 33, NO.2
A PUBLICATION BY: THE UNIVERSITY OF KENTUCKY DEPARTMENT OF VETERINARY SCIENCE, MAXWELL H. GLUCK EQUINE RESEARCH CENTER FUNDED BY: EQUUS / STANDARDBRED STATION, INC. M&J INSURANCE
IN THIS ISSUE
R E SE A R C H SPOTLIGHT
INTERNATIONAL
Growing Equine ‘Mini-Guts’ to Investigate Infectious Causes of Intestinal Illness in the Horse
First Quarter 2024..............P. 3 NATIONAL
Vesicular Stomatitis Returns with a New Bag of Tricks..P. 4 KENTUCKY
The 2022 Kentucky Equine Survey: Measuring a Decade of Change......... P. 5,6 KENTUCKY
Insulin Dysregulation (ID) and the Link to Laminitis: “Why Diagnostic Testing is Important”...............P. 6,7,8 T H ANK YOU S PON SO RS!
Gastrointestinal disorders represent a range of serious, potentially life-threatening conditions that continue to be a major challenge to horse owners and the equine industry, leading to significant financial costs associated with prevention and treatment as well as the loss of horses of all ages. A major roadblock in studying and understanding disease outcomes associated with infectious causes of colic is a lack of relevant laboratory model systems in which to model intestinal infections. To overcome this obstacle, the Shaffer Laboratory developed microscopic, organ-like systems (termed ‘organoids’) from a variety of horse tissues to study bacterial and viral equine infectious diseases. Importantly, due to their unlimited self-renewal and tissue expansion, organoids bridge the gap between the laboratory and disease models, providing an attractive alternative to animal experimentation. In addition, organoids have emerged as an invaluable tool for accurately predicting drug metabolism and response, such that they represent an ideal platform for therapeutic discovery and pre-clinical development. When generated from the intestines, minigut organoids (referred to as ‘enteroids’) reproduce the unique characteristics and microarchitecture of the equine gastrointestinal tract, providing a robust laboratory model to mimic the horse intestine. While enteroids grown in a three-dimensional (3D) configuration are beneficial for long-term culture and functional characterization, host-pathogen interactions are more challenging to model. For example, enteroids grow in a wide range
of shapes and sizes, leading to inconsistent approximation of equine cell numbers and inaccurate or unpredictable bacteria-to-cell ratios. Moreover, pathogens invade tissues using receptors localized to the luminal host cell surface. Unfortunately, ensuring that bacteria or viruses gain access to the enteroid interior where luminal cell receptors are located is technically challenging, time-consuming and difficult to standardize. To address this challenge, our lab developed methods to manipulate enteroids to allow bacteria or viruses access to critical cell receptors. Our first approach involves imbedding parts of enteroids onto a semipermeable membrane submerged into specialized media that encourages normal cell division and architecture. In this system, enteroids selfassemble such that the luminal cell surfaces (those that would normally be on the inside of the intestine) are exposed and accessible from the top of the culture dish. This technique provides a more convenient, consistent and precise way to control equine cell numbers and allows us to easily infect enteroid-derived tissues. Our second method involves attaching enteroid tissue onto microfluidic chip devices capable of directional fluid flow and mechanical deformation that applies physical stretch across the chip. Critically, these normal, physiologic forces generate a tissue microenvironment that more accurately mimics the directional flow of digesta traveling through the gut via wavelike peristalsis. These chips developed in our lab consist of two parallel channels separated by a semipermeable membrane that enables “cross-talk” between the interfaced gut tissue and an artificial vasculature created by an equine endothelial cell barrier.
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