Establishment of a model for equine small intestinal disease: effects of extracorporeal blood perfusion of equine ileum on metabolic variables and histological morphology – an experimental ex vivo study

Abstract

BackgroundIn horses a number of small intestinal diseases is potentially life threatening. Among them are Equine Grass Sickness (EGS), which is characterised by enteric neurodegeneration of unknown aetiology, as well as reperfusion injury of ischaemic intestine (I/R), and post-operative ileus (POI), common after colic surgery. The perfusion of isolated organs is successfully used to minimize animal testing for the study of pathophysiology in other scenarios. However, extracorporeal perfusion of equine ileum sourced from horses slaughtered for meat production has not yet been described. Therefore the present study evaluated the potential of such a model for the investigation of small intestinal diseases in an ex vivo and cost-efficient system avoiding experiments in live animals.ResultNine ileum specimens were sourced from horses aged 1–10 years after routine slaughter at a commercial abattoir. Ileum perfusion with oxygenated autologous blood and plasma was successfully performed for 4 h in a warm isotonic bath (37.0–37.5 °C). Ileum specimens had good motility and overall pink to red mucosa throughout the experiment; blood parameters indicated good tissue vitality: 82 ± 34 mmHg mean arterial partial pressure of oxygen (pO2) compared to 50 ± 17 mmHg mean venous pO2, 48 ± 10 mmHg mean arterial partial pressure of carbon dioxide (pCO2) compared to 66 ± 7 mmHg venous pCO2 and 9.8 ± 2.8 mmol/L mean arterial lactate compared to 11.6 ± 2.7 mmol/L venous lactate. There was a mild increase in ileum mass reaching 105 ± 7.5% of the pre-perfusion mass after 4 hours. Histology of haematoxylin and eosin stained biopsy samples taken at the end of perfusion showed on average 99% (±1%) histologically normal neurons in the submucosal plexus and 76.1% (±23.9%) histologically normal neurons in the myenteric plexus and were not significantly different to control biopsies.ConclusionExtracorporeal, normothermic perfusion of equine ileum over 4 h using autologous oxygenated blood/plasma perfusate showed potential as experimental model to test whether haematogenous or intestinal exposure to neurotoxins suspected in the pathogenesis of EGS can induce neuronal damage typical for EGS. Also, this model may allow investigations into the effect of pharmaceuticals on I/R injury, as well as into the pathogenesis of equine POI.

Normothermic Machine Perfusion Systems: Where Do We Go From Here?

“…Studies have explored intestinal segment perfusion to develop in vivo-like preclinical models for research in gastroenterology and intestinal transplantation 120,121 (Table 3). Unterköfler et al 120 developed an NMP platform to perfuse ilea from DCD horses for 4 h, which employed a solution based on autologous blood and plasma perfused through the aboral artery and recirculated through cannulated aboral and oral veins. The authors confirmed intestinal viability via general NMP analyses and ileal motility; however, they noted increased organ weight and lactate levels.…”

“…The administration of therapies through the perfusate has several benefits that make NMP an attractive therapeutic option, including more efficient delivery, lower doses, and reduced unwanted side effects in nontarget organs. 174 The immunomodulatory properties of mesenchymal stem cells 57–159 and multipotent adult progenitor cells 160–162 have shown beneficial effects during liver, lung, and kidney NMP, presumably due to their immunomodulatory properties, which prompt both anti-inflammatory and regenerative responses. 157,160–162 In human models, initially discarded kidneys 160 and livers 161 treated with multipotent adult progenitor cells or preterm-neonate progenitor cells 162 exhibited improved viability, even meeting established criteria.…”