Histology and transcriptome insights into the early processes of intestinal anastomotic healing: a rat model

Abstract Background Understanding the early processes underlying intestinal anastomotic healing is crucial to comprehend the pathophysiology of anastomotic leakage. The aim of this study was to assess normal intestinal anastomotic healing and disturbed healing in rats to investigate morphological, cellular and intrinsic molecular changes in the anastomotic tissue. Method Anastomoses were created in two groups of Wistar rats, using four sutures or 12 sutures to mimic anastomotic leakage and anastomotic healing respectively. At 6, 12, 24 hours and 2, 3, 5 and 7 days, anastomotic tissue was assessed macroscopically using the anastomotic complication score and histologically using the modified Ehrlich–Hunt score. Transcriptome analysis was performed to assess differences between anastomotic leakage and anastomotic healing at the first three time points to find affected genes and biological processes. Results Ninety-eight rats were operated on (49 animals in the anastomotic leakage and 49 in the anastomotic healing group) and seven rats analysed at each time point. None of the animals with 12 sutures developed anastomotic leakage macroscopically, whereas 35 of the 49 animals with four sutures developed anastomotic leakage. Histological analysis showed increasing influx of inflammatory cells up to 3 days in anastomotic healing and up to 7 days in anastomotic leakage, and this increase was significantly higher in anastomotic leakage at 5 (P = 0.041) and 7 days (P = 0.003). Transcriptome analyses revealed large differences between anastomotic leakage and anastomotic healing at 6 and 24 hours, mainly driven by an overall downregulation of genes in anastomotic leakage. Conclusion Transcriptomic analyses revealed large differences between normal and disturbed healing at 6 hours after surgery, which might eventually serve as early-onset biomarkers for anastomotic leakage. In order to develop efficient interventions preventing anastomotic leakage and to better predict if a patient will develop anastomotic leakage, it is crucial to understand the underlying mechanisms of normal and disturbed anastomotic healing. In this animal model, the healing process over time was investigated and it was observed that the sequential phases of intestinal healing resemble the sequential phases of skin healing. Furthermore, 6 hours after anastomosis creation, transcriptional differences are present in the anastomotic tissue between healing and disturbed healing. These findings could be