Changes in equine intestinal stem/progenitor cell number at resection margins in cases of small intestinal strangulation.

Abstract

Intestinal epithelial stem cells (ISC) are responsible for epithelial regeneration and are critical to the intestine's ability to regain barrier function following injury. Evaluating ISC biomarker expression in cases of small intestinal strangulation (SIS) may provide insight into clinical progression. Intestinal resection margins from cases of SIS were evaluated to determine if (1) evidence of injury could be identified using histomorphometry, (2) ISC biomarker expression was decreased in the proximal resection margin compared to control and distal resection margin, and (3) the ISC biomarker expression was associated with the number of preoperative risk factors negatively related to outcome, post-operative complications, or case outcome. Retrospective cohort study. Intestinal samples were obtained intraoperatively from resection margins of adult horses with SIS and horses euthanised for reasons unrelated to colic. Preoperative risk factors negatively related to outcome, post-operative complications, and case outcome were obtained from medical records. Horses were grouped as euthanised intraoperatively, postoperatively, or survived to discharge. Histomorphometry and immunofluorescence were performed to evaluate tissue architecture and ISC and progenitor cell number. Groups were compared using one-way ANOVA. Associations between biomarker expression and the number of preoperative risk factors and post-operative complications negatively related to outcome were determined using linear regression modelling. Thirty-six cases of SIS were evaluated. Ki67+ cell counts were decreased in the proximal (mean=15.45 cells; 95% CI= 10.27-20.63; SD=4.17; p= 0.02) and distal resection margins (mean=15.05; 95% CI=8.46-21.64; SD=4.141; p= 0.03) in horses euthanised postoperatively compared to control (mean=23.62 cells; 95% CI=19.42-27.83; SD=5.883). In the distal resection margin, an increase in SOX9+ Ki67+ cells were associated with a decrease in the total number of preoperative risk factors negatively related to outcome (95% CI = 0.236-1.123; p= 0.008, SE=0.1393). Small population size. Proliferating cell and ISC numbers may be associated with case outcome.