Lazaroid (U74389G)-supplemented cardioplegia: results of a double-blind, randomized, controlled trial in a porcine model of orthotopic heart transplantation

Experimental isolation and preservation of solid organs before transplantation: effects of pretreatment using four different molecules

OBJECTIVES

In transplantation surgery, the ischaemic organ and reperfusion impairment after cold storage remains a considerable risk factor for impaired function and potential failure of the grafted organ. Substantial logistical efforts have been undertaken to reduce the cold ischaemic time because the demand for available transplant organs and the periods of cold ischaemia are increasing.

METHODS

Four molecules were investigated (erythropoietin, sildenafil, lazaroid [U74389G], octreotide) in individual intravenous infusions 1 hour before the organ was harvested. This study was performed in 30 healthy landrace/large-white pigs (male; >10 weeks old; average weight, 22 ± 2 kg) in groups of six. The organs were studied at harvest, and at 8 and 24 hours post-harvest.

RESULTS

The lazaroid molecule increased malondialdehyde (MDA) levels in the liver and pancreas at 8 hours. Hepatic lazaroid molecules improved liver histology at 8 and 24 hours. For kidneys, erythropoietin had a positive effect at 24 hours post-harvest. For the pancreas, octreotide showed better performance. In the lungs, there was less interstitial oedema with erythropoietin and lazaroid compared with the control group at 8 hours post-harvest.

CONCLUSION

All molecules had a positive effect and decreased ischaemia/reperfusion graft injury. Thus, pretreatment before organ harvest has a beneficial role.

Compromised right ventricular contractility in an ovine model of heart transplantation following 24 h donor brain stem death

BACKGROUND

Heart failure is an inexorably progressive disease with a high mortality, for which heart transplantation (HTx) remains the gold standard treatment. Currently, donor hearts are primarily derived from patients following brain stem death (BSD). BSD causes activation of the sympathetic nervous system, increases endothelin levels, and triggers significant inflammation that together with potential myocardial injury associated with the transplant procedure, may affect contractility of the donor heart. We examined peri-transplant myocardial catecholamine sensitivity and cardiac contractility post-BSD and transplantation in a clinically relevant ovine model.

METHODS

Donor sheep underwent BSD (BSD, n = 5) or sham (no BSD) procedures (SHAM, n = 4) and were monitored for 24h prior to heart procurement. Orthotopic HTx was performed on a separate group of donor animals following 24h of BSD (BSD-Tx, n = 6) or SHAM injury (SH-Tx, n = 5). The healthy recipient heart was used as a control (HC, n = 11). A cumulative concentration-effect curve to (-)-noradrenaline (NA) was established using left (LV) and right ventricular (RV) trabeculae to determine β₁-adrenoceptor mediated potency (-logEC₅₀ [(-)-noradrenaline] M) and maximal contractility (Emax).

RESULTS

Our data showed reduced basal and maximal (-)-noradrenaline induced contractility of the RV (but not LV) following BSD as well as HTx, regardless of whether the donor heart was exposed to BSD or SHAM. The potency of (-)-noradrenaline was lower in left and right ventricles for BSD-Tx and SH-Tx compared to HC.

CONCLUSION

These studies show that the combination of BSD and transplantation are likely to impair contractility of the donor heart, particularly for the RV. For the donor heart, this contractile dysfunction appears to be independent of changes to β₁-adrenoceptor sensitivity. However, altered β₁-adrenoceptor signalling is likely to be involved in post-HTx contractile dysfunction.

Heart Transplantation From Brain Dead Donors: A Systematic Review of Animal Models

Despite advances in mechanical circulatory devices and pharmacologic therapies, heart transplantation (HTx) is the definitive and most effective therapy for an important proportion of qualifying patients with end-stage heart failure. However, the demand for donor hearts significantly outweighs the supply. Hearts are sourced from donors following brain death, which exposes donor hearts to substantial pathophysiological perturbations that can influence heart transplant success and recipient survival. Although significant advances in recipient selection, donor and HTx recipient management, immunosuppression, and pretransplant mechanical circulatory support have been achieved, primary graft dysfunction after cardiac transplantation continues to be an important cause of morbidity and mortality. Animal models, when appropriate, can guide/inform medical practice, and fill gaps in knowledge that are unattainable in clinical settings. Consequently, we performed a systematic review of existing animal models that incorporate donor brain death and subsequent HTx and assessed studies for scientific rigor and clinical relevance. Following literature screening via the U.S National Library of Medicine bibliographic database (MEDLINE) and Embase, 29 studies were assessed. Analysis of included studies identified marked heterogeneity in animal models of donor brain death coupled to HTx, with few research groups worldwide identified as utilizing these models. General reporting of important determinants of heart transplant success was mixed, and assessment of posttransplant cardiac function was limited to an invasive technique (pressure-volume analysis), which is limitedly applied in clinical settings. This review highlights translational challenges between available animal models and clinical heart transplant settings that are potentially hindering advancement of this field of investigation.

Oxidative Stress-Responsive MicroRNAs in Heart Injury

Reactive oxygen species (ROS) are important molecules in the living organisms as a part of many signaling pathways. However, if overproduced, they also play a significant role in the development of cardiovascular diseases, such as arrhythmia, cardiomyopathy, ischemia/reperfusion injury (e.g., myocardial infarction and heart transplantation), and heart failure. As a result of oxidative stress action, apoptosis, hypertrophy, and fibrosis may occur. MicroRNAs (miRNAs) represent important endogenous nucleotides that regulate many biological processes, including those involved in heart damage caused by oxidative stress. Oxidative stress can alter the expression level of many miRNAs. These changes in miRNA expression occur mainly via modulation of nuclear factor erythroid 2-related factor 2 (Nrf2), sirtuins, calcineurin/nuclear factor of activated T cell (NFAT), or nuclear factor kappa B (NF-κB) pathways. Up until now, several circulating miRNAs have been reported to be potential biomarkers of ROS-related cardiac diseases, including myocardial infarction, hypertrophy, ischemia/reperfusion, and heart failure, such as miRNA-499, miRNA-199, miRNA-21, miRNA-144, miRNA-208a, miRNA-34a, etc. On the other hand, a lot of studies are aimed at using miRNAs for therapeutic purposes. This review points to the need for studying the role of redox-sensitive miRNAs, to identify more effective biomarkers and develop better therapeutic targets for oxidative-stress-related heart diseases.

Preservation of the donor heart: from basic science to clinical studies

The methods of donor heart preservation are aimed at minimizing graft dysfunction caused by ischaemia-reperfusion injury (IRI) which inevitably occurs during the ex vivo transport interval. At present, the standard technique of heart preservation is cardiac arrest followed by static cold storage in a crystalloid heart preservation solution (HPS). This technique ensures an acceptable level of heart protection against IRI for <6 h. In clinical trials, comparable levels of myocardial protection against IRI were provided by various HPSs. The growing shortage of donor hearts is one of the major factors stimulating the development of new techniques of heart preservation. Here, we summarize new HPS formulations and provide a focus for optimization of the composition of existing HPSs. Such methods of donor heart preservation as machine perfusion, preservation at sub-zero temperature and oxygen persufflation are also discussed. Furthermore, we review experimental data showing that pre- and post-conditioning of the cardiac graft can improve its function when used in combination with cold storage. The evidence on the feasibility of cardiac donation after circulatory death, as well as the techniques of heart reconditioning after a period of warm ischaemia, is presented. The implementation of new techniques of donor heart preservation may contribute to the use of hearts from extended criteria donors, thereby expanding the total donor pool.

Natural orifice versus conventional laparoscopic distal pancreatectomy in a porcine model: a randomized, controlled trial

BACKGROUND

Natural orifice transluminal endoscopic surgery (NOTES) research has primarily involved case series reports of low-risk procedures. Distal pancreatectomy has significant postoperative morbidity and would permit rigorous examination in a controlled trial setting.

OBJECTIVE

To compare endoscopic transgastric distal pancreatectomy (ETDP) and laparoscopic distal pancreatectomy (LDP).

DESIGN

Prospective, randomized, controlled trial.

SETTING

Academic hospital.

SUBJECTS

Forty-one swine, 28 block randomized.

INTERVENTIONS

LDP was performed with 3 trocars and stapled transection of the pancreas. ETDP was performed via a gastrotomy, with 1 trocar for visualization, by using endoloop placement, snare transection, and purse-string gastrotomy closure.

MAIN OUTCOME MEASUREMENTS

Clinical examination, CT, serum chemistries, necropsy, peritoneal fluid analysis, and histologic examination.

RESULTS

Swine were survived for 8 days. The procedure time for ETDP was significantly greater than for LDP (1:52 vs 0:33 [hours:minutes]; P = .00). Pancreatic specimen weight was similar (4.1 g vs 5.5 g; P = .108). Postoperatively, 26 of 28 animals thrived. In the LDP group, 1 death caused by pancreatic leak and renal failure occurred on day 1. In the ETDP group, 1 death caused by pneumothorax occurred intraoperatively. The necropsy, CT, and histologic examinations revealed focal resection-margin necrosis in 3 to 7 swine in the ETDP group with no proximal necrosis or pancreatitis. The groups were equivalent clinically, by survival, and by serum and peritoneal fluid analysis. The gastrotomy closure was associated with small serosal adhesions, but no gross abscess or necrosis.

LIMITATION

Animal study.

CONCLUSIONS

In the largest controlled trial of NOTES orifice surgery to date, there was no clinical or survival difference between NOTES and laparoscopic approaches.