Preconditioning, organ preservation, and postconditioning to prevent ischemia-reperfusion injury to the liver

Expression of genes involved in rat liver angiogenesis after ischaemia and reperfusion: effects of ischaemic pre- and post-conditioning

BACKGROUND

During surgery, ischaemic pre- (IPC) and post-conditioning (IPO) protects the liver against ischaemia/reperfusion injuries (I/R-injuries). The impact of ischaemic conditioning on liver regeneration has been less well studied. Angiogenesis is an important part of liver regeneration after hepatectomy. The aim of the present study was to investigate the effect of ischaemia/reperfusion and ischaemic conditioning on the expression of genes with angiogenic potential in a model of rat liver ischaemia.

METHODS

A model of total liver ischaemia (30 min) and reperfusion (30 min) was employed using Wistar rats. Rats were randomized into five groups: (C) control (IRI) ischaemic, IPC, IPO and IPC + IPO. Liver enzymes were sampled at the end of reperfusion. Liver biopsies were analysed using cDNA microarrays.

RESULTS

Alanine aminotransferase (ALT) increased significantly in all the ischaemic groups compared with controls (P= 0.000). Searching databases 99 genes involved in rat liver angiogenesis were identified. Compared with group (C) the number of genes significantly up-regulated was as follows: IRI (n= 5), IPC (n= 24), IPO (n= 33) and IPC + IPO (n= 18). No genes were down-regulated in the four groups compared with controls.

CONCLUSION

Ischaemic conditioning, as demonstrated in the present study, seems to be potent activators of angiogenic genes. This might be favourable to the regenerating liver.

Role of heme oxygenase-1 in transplantation

Heme oxygenase-1 (HO-1) is the rate-limiting enzyme in heme catabolism that converts heme to Fe++, carbon monoxide and biliverdin. HO-1 acts anti-inflammatory and modulates apoptosis in many pathological conditions. In transplantation, HO-1 is overexpressed in organs during brain death, when undergoing ischemic damage and rejection. However, intentionally induced, it ameliorates pathological processes like ischemia reperfusion injury, allograft, xenograft or islet rejection, facilitates donor specific tolerance and alleviates chronic allograft changes. We herein consistently summarize the huge amount of data on HO-1 and transplantation that have been generated in multiple laboratories during the last 15years and suggest possible clinical implications and applications for the near future.

Donor intervention and organ preservation: where is the science and what are the obstacles?

The organ shortage is widely acknowledged as the most critical factor hindering the full realization of success for solid organ transplantation. Innovation in the areas of donor management and organ preservation offers the most realistic hope to improve both the quality and size of the current organ supply. Although the basic science dissecting the complex processes of brain death and ischemia/reperfusion injury is replete with exciting discoveries, the clinical science investigating donor management and organ preservation is sparse in contrast. This review will survey the current landscape of trials to mitigate organ injury through interventions administered to donors in vivo or organs ex vivo. Consideration will then be given to the scientific, logistical and ethical obstacles that impede the transformation of laboratory breakthroughs into innovative treatments that simultaneously improve organ quality and supply.