Ischemic preconditioning in the animal kidney, a systematic review and meta-analysis. PLoS One. 2012;7:e32296. [PMID: 22389693 PMCID: PMC3289650 DOI: 10.1371/journal.pone.0032296]

Cardiovascular pharmacotherapy: Innovation stuck in translation

Systematic reviews of animal studies have revealed serious limitations in internal and external validity strongly affecting the reliability of this research. In addition inter-species differences are likely to further limit the predictive value of animal research for the efficacy and tolerability of new drugs in humans. Important changes in the research process are needed to allow efficient translation of preclinical discoveries to the clinic, including improvements in the laboratory and publication practices involving animal research and early incorporation of human proof-of-concept studies to optimize the interpretation of animal data for its predictive value for humans and the design of clinical trials.

Impact of ischemic preconditioning on outcome in clinical liver surgery: a systematic review

Background. Ischemia-reperfusion injury is a major cause of post-liver-surgery complications. Ischemic preconditioning (IPC) has been demonstrated to protect against ischemia-reperfusion injury. Clinical studies have examined IPC in liver surgery but with conflicting results. This systematic review aimed to evaluate the effects of IPC on outcome in clinical liver surgery. Methods. An electronic search of OVID Medline and Embase databases was performed to identify studies that reported outcomes in patients undergoing liver surgery subjected to IPC. Basic descriptive statistics were used to summarise data from individual clinical studies. Results. 1093 articles were identified, of which 24 met the inclusion criteria. Seven topics were selected and analysed by subgroup. There were 10 studies in cadaveric liver transplantation, 2 in living-related liver transplantation, and 12 in liver resection. IPC decreases hepatocellular damage in liver surgery as determined by transaminases but does not translate to any significant clinical benefit in orthotopic liver transplant or liver resection. Conclusions. Available clinical evidence does not support routine use of IPC in liver surgery as it does not offer any apparent benefit in perioperative outcome. Further clinical studies will need to be carried out to determine the subset of patients that will benefit from IPC.

Effects of ischemic preconditioning on the systemic and renal hemodynamic changes in renal ischemia reperfusion injury

BACKGROUND

Ischemic preconditioning (IPC) could protect against subsequent renal ischemia reperfusion injury (IRI). However, the mechanisms underlying IPC remain far from complete. Hence, we explored the effects of IPC on the renal and systemic hemodynamic changes, renal function and morphology, as well the involvement of endothelial and inducible nitric oxide synthase (eNOS/iNOS), and nitric oxide (NO).

METHODS

Male Sprague-Dawley rats were randomly divided into five groups after right-side nephrectomy: Sham group (surgery without vascular clamping); IRI group (the left renal artery was clamped for 45 min); IPC group (pretreated with 15 min of ischemia and 10 min of reperfusion); IPC + vehicle group (administrated with 0.9% saline 5 min before IPC); and IPC + N(G)-nitro-L-arginine methylester (L-NAME) group (pretreated with L-NAME 5 min prior to IPC). The renal and systemic hemodynamic parameters, renal function and morphology, as well as eNOS, iNOS, and NO expression levels in the kidneys were measured at the indicated time points after reperfusion.

RESULTS

IPC rats exhibited significant improvements in renal function, morphology, and renal artery blood flow (RABF), without obvious influence on the systemic hemodynamics and renal vein blood flow. Increased eNOS, iNOS, and NO expression levels were detected in the kidneys of IPC rats 24 h after reperfusion. Furthermore, the beneficial effects were fully abolished by the administration of L-NAME.

CONCLUSIONS

The results suggest that IPC contributes to early restoration of RABF, probably through eNOS/iNOS-mediated NO production, thereby alleviating the renal dysfunction and histological damage caused by IRI.

Cell-based therapies for experimental chronic kidney disease: a systematic review and meta-analysis

Cell-based therapy is a promising strategy for treating chronic kidney disease (CKD) and is currently the focus of preclinical studies. We performed a systematic review and meta-analysis to evaluate the efficacy of cell-based therapy in preclinical (animal) studies of CKD, and determined factors affecting cell-based therapy efficacy in order to guide future clinical trials. In total, 71 articles met the inclusion criteria. Standardised mean differences (SMD) and 95% confidence intervals (CI) were calculated for outcome parameters including plasma urea, plasma creatinine, urinary protein, blood pressure, glomerular filtration rate, glomerulosclerosis and interstitial fibrosis. Sub-analysis for each outcome measure was performed for model-related factors (species, gender, model and timing of therapy) and cell-related factors (cell type, condition and origin, administration route and regime of therapy). Overall, meta-analysis showed that cell-based therapy reduced the development and progression of CKD. This was most prominent for urinary protein (SMD, 1.34; 95% CI, 1.00–1.68) and urea (1.09; 0.66–1.51), both P<0.001. Changes in plasma urea were associated with changes in both glomerulosclerosis and interstitial fibrosis. Sub-analysis showed that cell type (bone-marrow-derived progenitors and mesenchymal stromal cells being most effective) and administration route (intravenous or renal artery injection) were significant predictors of therapeutic efficacy. The timing of therapy in relation to clinical manifestation of disease, and cell origin and dose, were not associated with efficacy. Our meta-analysis confirms that cell-based therapies improve impaired renal function and morphology in preclinical models of CKD. Our analyses can be used to optimise experimental interventions and thus support both improved preclinical research and development of cell-based therapeutic interventions in a clinical setting.

Activation of the calcium-sensing receptor before renal ischemia/reperfusion exacerbates kidney injury

Activation of the calcium-sensing receptor (CaSR) by ischemia/reperfusion (I/R) favours apoptosis in cardiomyocytes, hepatocytes and neurons. Its role in renal I/R is unknown. We investigated the impact of pharmacological preactivation of the CaSR on kidney structure and function in a murine model of bilateral renal 30-min ischemia and 48-hour reperfusion, and in a 6-year cohort of kidney transplant recipients (KTR). C57BL/6J mice were administered daily with CaSR agonist, R-568, or with vehicle for 48 hours. Evaluation of serum urea and creatinine levels, renal histology and urine metabolome by nuclear magnetic resonance showed that R-568 was not nephrotoxic per se. Following I/R, serum urea and creatinine levels increased higher in R-568-treated animals than in controls. Jablonski's score was significantly greater in R-568-treated kidneys, which showed a higher rate of cell proliferation and apoptosis in comparison to controls. Next, we retrospectively identified 36 patients (10.7% of our cohort) who were treated by CaSR agonist, cinacalcet, at the time of kidney transplantation (KTx). After matching these to 61 KTR upon type of donor, cold ischemic time, residual diuresis, and donor age, we observed that delayed graft function, i.e. need for dialysis in the first week after KTx, occurred in 42 and 23% of cinacalcet-treated and control groups, respectively (p≤0.05). These data suggest that pharmacological preactivation of the CaSR before renal I/R exacerbates kidney injury.

Impact of ischaemic preconditioning on experimental steatotic livers following hepatic ischaemia-reperfusion injury: a systematic review

BACKGROUND

Steatotic livers are vulnerable to the deleterious effects of ischaemia-reperfusion injury (IRI) that occur after hepatic surgery. Ischaemic preconditioning (IPC) has been shown to abrogate the effects of IRI in patients undergoing hepatic surgery. Experimental studies have suggested that IPC may be beneficial in steatotic livers subjected to IRI.

OBJECTIVE

The aim of this systematic review was to evaluate the effects of IPC on steatotic livers following hepatic IRI in experimental models.

METHODS

An electronic search of the OVID Medline and EMBASE databases was performed to identify studies that reported clinically relevant outcomes in animal models of hepatic steatosis subjected to IPC and IRI.

RESULTS

A total of 1093 articles were identified, of which 18 met the inclusion criteria. There was considerable heterogeneity in the type of animal model, and duration and type of IRI. Increased macrovesicular steatosis (> 30%) was associated with a poor outcome following IRI. Ischaemic preconditioning was found to be beneficial in > 30% steatotic livers and provided for decreased histological damage, improved liver function findings and increased survival.

CONCLUSIONS

Experimental evidence supports the use of IPC in steatotic livers undergoing IRI. These findings may be applicable to patients undergoing liver surgery. However, clinical studies are required to validate the efficacy of IPC in this setting.

Design, study quality and evidence of analgesic efficacy in studies of drugs in models of OA pain: a systematic review and a meta-analysis

OBJECTIVE

Studies using animal models are important in drug development, but often poorly predict treatment results in man. We investigated factors that may impact on the magnitude of the analgesic treatment effect in animal models of osteoarthritis (OA) pain.

DESIGN

Systematic review of studies that measured behavioural pain outcomes in small animal models of OA, and tested drugs which reduce OA pain in man. Standardised mean difference (SMD) and 95% confidence intervals (CIs) were calculated using random effects meta-analysis for selected models and drugs.

RESULTS

Most studies used rat models (42/50) and chemical methods of OA induction (39/50). Analgesic treatment effect (SMD) was most commonly measured between drug- and vehicle treated rats with knee OA. Meta-analysis was carried out for 102 such comparisons from 26 studies. The pooled SMD was 1.36 (95% CI = 1.15-1.57). Non-steroidal anti-inflammatory drugs (NSAIDs) were associated with smaller SMDs than opioids (z = -3.25, P = 0.001). Grip strength gave larger SMDs than assessment of static weight bearing (z = -4.60, P < 0.001), mechanically-evoked pain (z = -3.83, P = 0.001) and movement-evoked pain (z = -5.23, P < 0.001), and SMDs for mechanically-evoked pain were larger than for movement-evoked pain (z = -2.78, P = 0.006). Studies that reported structural evaluation of OA phenotype were associated with smaller SMDs (z = -2.45, P = 0.014). Publication was significantly biased towards positive findings.

CONCLUSION

Attention to study-level moderators and publication bias may improve the ability of research using animal models to predict whether analgesic agents will reduce arthritis pain in man.

Benefits of remote ischaemic preconditioning in vascular surgery

OBJECTIVES

Remote ischaemic preconditioning (RIPC) is a physiological mechanism to protect against ischaemia-reperfusion injury. It is a technique in which short pre-emptive periods of ischaemia and reperfusion are thought to protect against ischaemia-reperfusion injury during procedures requiring longer periods of ischaemia. Discovered in the 1980s, its clinical application has been investigated heavily since the first human study in 2006. The aim of this paper was to provide a review of this rapidly expanding subject.

METHODS

This study consists of a narrative review of the literature focusing on previous meta-analyses and randomised control trials.

RESULTS

Five small randomised trials have been published on the effects of RIPC in vascular surgery. Several randomised trials have been published in cardiac surgery and percutaneous coronary intervention. Meta-analysis shows a significant reduction in troponin levels and biomarkers of renal dysfunction in RIPC patients, but as yet no convincing clinical benefit. The largest powered randomised trial in cardiac surgery showed no benefit to RIPC.

CONCLUSIONS

Current trials and therefore meta-analyses are generally underpowered. The technique is physiologically sound but remains lacking in clear clinical benefit.

Mechanisms of epithelial repair and regeneration after acute kidney injury

Acute kidney injury (AKI) is a common clinical problem and is associated with high mortality rates. It is accepted that after AKI cellular regeneration of the proximal tubule occurs from intrinsic tubule cells. Recently, scattered tubular cells (STCs) were discovered as a novel subpopulation of tubule cells involved in regeneration. STCs have a distinct morphology, unique protein expression profile resembling that of parietal epithelial cells, proliferate more than the remaining proximal tubule cells, and are less susceptible to injuries. In response to AKI, STCs become more numerous, independent of the primary insult (ischemic, acute obstruction, and so forth). STCs can be detected with the highest sensitivity and manipulated by the parietal epithelial cell-specific, doxycycline inducible transgenic mouse line PEC-rtTA. In cell fate tracing experiments it was shown that STCs are not a fixed progenitor population. Rather, STCs arise from any surviving proximal tubule cell. Thus, the STC phenotype is a transient, graded, and specific transcriptional program facilitating tubular regeneration. Understanding this program my open new approaches to prevent and/or treat AKI.

Therapeutic effect of Soshiho-tang, a traditional herbal formula, on liver fibrosis or cirrhosis in animal models: a systematic review and meta-analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Liver fibrosis has been recognized as a major lesion of the liver that leads to liver cirrhosis at the end stage. Soshiho-tang (SST) has been used to improve liver fibrosis/cirrhosis by ameliorating fibrosis-specific markers. This study aimed to assess the efficacy of SST on liver fibrosis/cirrhosis through a systematic review of the literature and meta-analysis using animal models.

MATERIALS AND METHODS

Studies of SST treatment in liver fibrosis/cirrhosis-induced animal models were searched by electronic data bases. The quality of the studies included was assessed and the efficacy of SST was evaluated based on markers from liver tissues and serum.

RESULTS

Among the 838 studies identified in the literature search, 20 studies that met the inclusion criteria were included in the analysis. SST significantly reduced the elevated levels of fibrosis markers, such as the degree of fibrosis, hydroxyproline, hyaluronic acid, transforming growth factor-β1, and procollagen III in liver tissues, and aspartate aminotransferase, alanine aminotransferase, procollagen III, tissue inhibitor of metalloproteinase-1, and type IV collagen in the serum.

CONCLUSIONS

SST was effective in decreasing pathologically increased markers in animal models of liver fibrosis/cirrhosis. A larger-scale of animals, well-designed animal study is expected to improve the methodological quality, heterogeneity, and potential biases of the meta-analysis.

The influence of age, gender and treatment with steroids on the incidence of osteonecrosis of the femoral head during the management of severe acute respiratory syndrome: a retrospective study

Corticosteroid use has been implicated in the development of osteonecrosis of the femoral head (ONFH). The exact mechanism and predisposing factors such as age, gender, dosage, type and combination of steroid treatment remain controversial. Between March and July 2003, a total of 539 patients with severe acute respiratory syndrome (SARS) were treated with five different types of steroid. There were 129 men (24%) and 410 women (76%) with a mean age of 33.7 years (21 to 59). Routine screening was undertaken with radiographs, MRI and/or CT to determine the incidence of ONFH. Of the 129 male patients with SARS, 51 (39.5%) were diagnosed as suffering from ONFH, compared with only 79 of 410 female patients (19.3%). The incidence of ONFH in the patients aged between 20 and 49 years was much higher than that of the group aged between 50 and 59 years (25.9% (127 of 491) versus 6.3% (3 of 48); p = 0.018). The incidence of ONFH in patients receiving one type of steroid was 12.5% (21 of 168), which was much lower than patients receiving two different types (28.6%; 96 of 336) or three different types of steroid (37.1%; 13 of 35).

SYRCLE's risk of bias tool for animal studies

Background

Systematic Reviews (SRs) of experimental animal studies are not yet common practice, but awareness of the merits of conducting such SRs is steadily increasing. As animal intervention studies differ from randomized clinical trials (RCT) in many aspects, the methodology for SRs of clinical trials needs to be adapted and optimized for animal intervention studies. The Cochrane Collaboration developed a Risk of Bias (RoB) tool to establish consistency and avoid discrepancies in assessing the methodological quality of RCTs. A similar initiative is warranted in the field of animal experimentation.

Methods

We provide an RoB tool for animal intervention studies (SYRCLE’s RoB tool). This tool is based on the Cochrane RoB tool and has been adjusted for aspects of bias that play a specific role in animal intervention studies. To enhance transparency and applicability, we formulated signalling questions to facilitate judgment.

Results

The resulting RoB tool for animal studies contains 10 entries. These entries are related to selection bias, performance bias, detection bias, attrition bias, reporting bias and other biases. Half these items are in agreement with the items in the Cochrane RoB tool. Most of the variations between the two tools are due to differences in design between RCTs and animal studies. Shortcomings in, or unfamiliarity with, specific aspects of experimental design of animal studies compared to clinical studies also play a role.

Conclusions

SYRCLE’s RoB tool is an adapted version of the Cochrane RoB tool. Widespread adoption and implementation of this tool will facilitate and improve critical appraisal of evidence from animal studies. This may subsequently enhance the efficiency of translating animal research into clinical practice and increase awareness of the necessity of improving the methodological quality of animal studies.

Assessing the application of the 3Rs: a survey among animal welfare officers in The Netherlands

Implementation of the 3Rs (Replacement, Refinement and Reduction) in animal studies is a legal requirement in many countries. In The Netherlands, animal welfare officers (AWOs) are appointed to monitor the welfare of laboratory animals. As part of this task, AWOs give advice to researchers and can therefore have an influential role in implementing 3R methods in research. A national survey was conducted to gain more insight into how Dutch AWOs obtain and apply 3R information in their daily work. Nearly half of the AWO population filled out the questionnaire (15/32; a response rate of 46.9%). Two-thirds of the respondents pointed out that finding 3R information is not an easy task and more than half of the respondents believed that information on possibilities to implement the 3Rs is regularly being missed. The respondents indicated that most 3R information is obtained directly from colleagues and other AWOs. Special online 3R databases are rarely used. All the responding AWOs feel that they contribute to Refinement (15/15), nearly one-third of the respondents feel they contribute to Reduction (4/15), and one AWO feels he/she contributes to Replacement (1/15). According to the respondents, better exchange of knowledge can contribute to more successful implementation of the 3Rs. How this knowledge exchange can best be established and facilitated needs further exploration. To this end, the authors make suggestions for a 3R-integrated evidence-based approach.

Ischaemic conditioning strategies for the nephrologist: a promise lost in translation?

Over the last quarter of a century, a huge effort has been made to develop interventions that can minimise ischaemia reperfusion injury. The most potent of these are the ischaemic conditioning strategies, which comprise ischaemic preconditioning, remote ischaemic preconditioning and ischaemic postconditioning. While much of the focus for these interventions has been on protecting the myocardium, other organs including the kidney can be similarly protected. However, translation of these beneficial effects from animal models into routine clinical practice has been less straightforward than expected. In this review, we examine the role of ischaemic conditioning strategies in reducing tissue injury from the 'bench to the bedside' and discuss the barriers to their greater translation.

Mesenchymal stromal cell therapy in conditions of renal ischaemia/reperfusion

Acute kidney injury (AKI) represents a worldwide public health issue of increasing incidence, with a significant morbi-mortality. AKI treatment mostly relies on supportive manoeuvres in the absence of specific target-oriented therapy. The pathophysiology of AKI commonly involves ischaemia/reperfusion (I/R) events, which cause both immune and metabolic consequences in renal tissue. Similarly, at the time of kidney transplantation (KT), I/R is an unavoidable event which contributes to early graft dysfunction and enhanced graft immunogenicity. Mesenchymal stromal cells (MSCs) represent a heterogeneous population of adult, fibroblast-like multi-potent cells characterized by their ability to differentiate into tissues of mesodermal lineages. Because MSC have demonstrated immunomodulatory, anti-inflammatory and tissue repair properties, MSC administration at the time of I/R and/or at later times has been hypothesized to attenuate AKI severity and to accelerate the regeneration process. Furthermore, MSC in KT could help prevent both I/R injury and acute rejection, thereby increasing graft function and survival. In this review, summarizing the encouraging observations in animal models and in pilot clinical trials, we outline the benefit of MSC therapy in AKI and KT, and envisage their putative role in renal ischaemic conditioning.

[Role of AMP-activated protein kinase in renal ischemic preconditioning]

Kidney transplantation represents the best treatment of end-stage renal disease. In addition to the degree of human leukocyte antigen matching, long-term graft survival is influenced by the quality of the graft before its transplantation. Quality criteria include the level of ischemic damage caused by the transplantation per se. Renal ischemic preconditioning (IP) consists of different approaches to prevent ischemia/reperfusion (I/R) damage induced by the interruption and recovery of renal circulation, as observed during transplantation. Distinct animal models show promising results regarding the efficiency of PCI to preserve kidney structure and function in I/R conditions. Characterizing the cellular cascades involved in I/R led to the identification of putative targets of renal IP, including the adenosine monophosphate-activated protein kinase (AMPK). AMPK is a ubiquitous energy sensor, which has been implicated in the maintenance of epithelial cell polarization under energy deprivation. Among others, the anti-diabetic drug, metformin, is a potent activator of AMPK. Here, we summarize the in vitro and in vivo data about the role of AMPK in renal IP. Defining the pharmacological conditions of IP would help to improve the quality of the renal graft before its transplantation, thereby increasing its long-term survival.

Remote ischemic preconditioning and renoprotection: from myth to a novel therapeutic option?

There is currently no effective prophylactic regimen available to prevent contrast-induced AKI (CI-AKI), a frequent and life-threatening complication after cardiac catheterization. Therefore, novel treatment strategies are required to decrease CI-AKI incidence and to improve clinical outcomes in these patients. Remote ischemic preconditioning (rIPC), defined as transient brief episodes of ischemia at a remote site before a subsequent prolonged ischemia/reperfusion injury of the target organ, is an adaptational response that protects against ischemic and reperfusion insult. Indeed, several studies demonstrated the tissue-protective effects of rIPC in various target organs, including the kidneys. In this regard, rIPC may offer a novel noninvasive and virtually cost-free treatment strategy for decreasing CI-AKI incidence. This review evaluates the current experimental and clinical evidence for rIPC as a potential renoprotective strategy, and discusses the underlying mechanisms and key areas for future research.

Molecular mechanisms of ischemic preconditioning and postconditioning as putative therapeutic targets to reduce tumor survival and malignancy

In tumors intermittent hypoxia has been reported to be more representative than normoxia or continuous exposure to low oxygen concentrations. Intermittent hypoxia is thought to increase tumor resistance against both anti-cancer therapy and the sustained ischemia that randomly occurs because of the dynamic nature of tumor vasculature. Here, we hypothesize that the molecular mechanisms underlying intermittent hypoxia in tumor cells share some triggers, modulators, and end-effectors of the intermittent episodes of ischemia and reperfusion that characterize ischemic preconditioning and postconditioning. These are among the most effective maneuvers protecting cells from ischemia-reperfusion injury. If this hypothesis were confirmed, several well-investigated molecular mediators of pre/post-conditioning could be explored as therapeutic targets against tumor malignancy. For examples, drugs that completely block the cardioprotection induced by ischemic preconditioning, such as mitochondrial potassium ATP channel inhibitors or mitochondrial permeability transition pore openers, could be extraordinarily efficient in counteracting the adaptations of tumor cells and cancer stem cells to intermittent hypoxia. As a consequence, this strategy should be effective in blunting tumor capacity to progress toward malignancy and survive in ischemic conditions.

Remote preconditioning reduces oxidative stress, downregulates cyclo-oxygenase-2 expression and attenuates ischaemia-reperfusion-induced acute kidney injury

Remote preconditioning (rPeC) is a phenomenon by which short-time intermittent ischaemia-reperfusion (I/R) of a remote organ during ischaemia protects other organs from I/R injury (IRI). The aim of the present study was to investigate the protective effect of rPeC on renal IRI in rats. Rats were subjected to right nephrectomy and randomized as into a sham group (no additional intervention), an I/R group (subjected to 45 min left renal pedicle occlusion) and an rPeC group (subjected to four cycles of 5 min I/R of the left femoral artery administered at the beginning of renal ischaemia). After 24 h, blood, urine and tissue samples were collected. Compared with the sham group, I/R resulted in renal dysfunction, as evidenced by significantly lower creatinine clearance (CCr; 0.52 ± 0.06 vs 0.11 ± 0.02 mL/min, respectively) and higher fractional excretion of sodium (FE(Na) ; 0.80 ± 0.07% vs 2.46 ± 0.20%, respectively). This was accompanied by decreased superoxide dismutase (SOD; 6.9 ± 1.7 vs 26.7 ± 2.7 U/g tissue) and catalase (CAT; 20.2 ± 8.8 vs 32.2 ± 8.7 K/g tissue) activity in the I/R group, as well as decreased levels of reduced glutathione (GSH; 21.7 ± 8.1 vs 81.2 ± 20.2 μmol/g tissue) and increased malondialdehyde levels (MDA; 1.2 to 0.1 vs 0.5 ± 0.2 μmol/100 mg), cyclo-oxygenase (COX)-2 expression and histological damage. In the rPeC group, renal histology and function were significantly improved (CCr 0.32 ± 0.02 mL/min; FE(Na) 1.33 ± 0.12%) compared with the I/R group. Furthermore, compared with the I/R group, the rPeC group exhibited increases in SOD and CAT activity (22.8 ± 3.8 U/g tissue and 21.7 ± 8.6 K/g tissue, respectively), increased GSH levels (74.0 ± 4.9) and decreased MDA levels (1.1 ± 0.3 μmol/100 mg) and COX-2 expression. In conclusion, rPeC appears to exert protective effects against renal IRI. This protection may be a consequence of reductions in lipid peroxidation, intensification of anti-oxidant systems and downregulation of COX-2 expression. A simple approach, rPeC may be a promising strategy for protection against IRI in clinical practice.

Reduction of myocardial infarct size with ischemic "conditioning": physiologic and technical considerations

A wealth of evidence has revealed that the heart can be "conditioned" and rendered less vulnerable to ischemia-reperfusion injury via the upregulation of endogenous protective signaling pathways. Three distinct conditioning strategies have been identified: (1) preconditioning, the phenomenon where brief episodes of myocardial ischemia (too brief to cause cardiomyocyte death) limit necrosis caused by a subsequent sustained ischemic insult; (2) postconditioning, the concept that relief of myocardial ischemia in a staged or stuttered manner attenuates lethal ischemia-reperfusion injury; and (3) remote conditioning, or upregulation of a cardioprotective phenotype initiated by ischemia in a remote organ or tissue and "transported" to the heart. Progress has been made in defining the technical requirements and limitations of each of the 3 ischemic conditioning models (including the timing and severity of the protective stimulus), as well as elucidating the molecular mechanisms (in particular, the receptor-mediated signaling pathways) responsible for conditioning-induced myocardial protection. Moreover, phase III clinical trials are in progress, seeking to capitalize on the protection that can be achieved by postconditioning and remote conditioning, and applying these strategies in patients undergoing cardiac surgery or angioplasty for the treatment of acute myocardial infarction. There is, however, a potentially important caveat to the clinical translation of myocardial conditioning: emerging data suggest that the efficacy of ischemic conditioning is compromised in aging, diabetic, and hypertensive cohorts, the specific populations in which myocardial protection is most relevant. Successful clinical application of myocardial conditioning will therefore require an understanding of the potential confounding consequences of these comorbidities on the "conditioned" phenotype.

Effect of ischemia preconditioning on renal ischemia/reperfusion injury in rats

OBJECTIVE

To study the effect of ischemia preconditioning (IP) on renal ischemia/reperfusion (I/R)-associated functional injury and expression of renal adhesion molecules in rats.

MATERIALS AND METHODS

The ischemia preconditioning plan adopted in this experiment involved renal warm ischemia for 6 min. and blood flow for 4 min., repeated four times. The Wistar rat kidneys used for warm ischemia preconditioning were subjected to 60 min of renal warm ischemia followed by reperfusion. The rat kidneys with ischemia/reperfusion were compared with the ischemia preconditioning group to observe rat renal function and changes in the expression of renal adhesion molecules ICAM-1, P-Selectin, and E-Selectin.

RESULTS

The expression of rat renal adhesion molecules (ICAM-1, P-Selectin, and E-Selectin) with ischemia preconditioning was significantly lower than that of the ischemia/reperfusion group. Serum creatinine was significantly lower than that in the ischemia/reperfusion group after 48 hours.

CONCLUSIONS

Ischemia preconditioning has a protective effect on renal function. Reduced expression of renal adhesion molecules is likely a mechanism involved in the observed protection.

Protection of organs other than the heart by remote ischemic conditioning

Organ or tissue dysfunction due to acute ischemia-reperfusion injury (IRI) is the leading cause of death and disability worldwide. Acute IRI induces cell injury and death in a wide variety of organs and tissues in a large number of different clinical settings. One novel therapeutic noninvasive intervention, capable of conferring multiorgan protection against acute IRI, is 'remote ischemic conditioning' (RIC). This describes an endogenous protective response to acute IRI, which is triggered by the application of one or more brief cycles of nonlethal ischemia and reperfusion to one particular organ or tissue. Originally discovered as a therapeutic strategy for protecting the myocardium against acute IRI, it has been subsequently demonstrated that RIC may confer protection against acute IRI in a number of different noncardiac organs and tissues including the kidneys, lungs, liver, skin flaps, ovaries, intestine, stomach and pancreas. The discovery that RIC can be induced noninvasively by applying the RIC stimulus to the skeletal tissue of the upper or lower limb has facilitated its application to a number of clinical settings in which organs and tissues are at high risk of acute IRI. In this article, we review the experimental studies that have investigated RIC in organs and tissues other than the heart, and we explore the therapeutic potential of RIC in preventing organ and tissue dysfunction induced by acute IRI.

Evaluation of the potential sensitization of chlorogenic Acid: a meta-analysis

Chlorogenic acid (CGA) widely exists in many plants, which are used as medicinal substances in traditional Chinese medicine injectables (TCMIs) that have been widely applied in clinical treatments. However, it is still controversial whether CGA is responsible for TCMIs-related hypersensitivity. Several studies have been performed to evaluate its potential sensitization property, but the results were inconclusive. Therefore, the aim of this study was to evaluate its potential sensitization systematically using meta-analysis based on data extracted from literatures, searching databases of PubMed, EMBASE, ISI Web of Knowledge, CNKI, VIP, and CHINAINFO from January 1979 to October 2012, a total of 108 articles were retrieved by electronic search strategy, out of which 13 studies met the inclusion criteria. In ASA test, odds ratio of behavior changes was 4.33 (1.62, 11.60), showing significant changes after CGA treatment (P = 0.004). Serum IgG, serum histamine, PLN cellularity, and IgG1 AFCs were significantly enhanced after CGA treatment (P < 0.05). Totally, these results indicated that CGA could induce a positive reaction in potential sensitization, and intravenous administration of it might be a key factor for sensitization triggering, which could at least warrant more careful application of TCMIs containing CGA in clinical practices.

Effect of remote ischaemic preconditioning on renal protection in patients undergoing laparoscopic partial nephrectomy: a 'blinded' randomised controlled trial

OBJECTIVE

To evaluate whether remote ischaemic preconditioning (RIPC) reduces renal injury in patients undergoing laparoscopic partial nephrectomy (LPN).

PATIENTS AND METHODS

In all, 82 patients undergoing LPN were randomly assigned to either the RIPC or control group, with 40 and 38 patients, respectively completing 6-months follow-up. RIPC was conducted after induction of anaesthesia, which consisted of three 5-min cycles of right lower limb ischaemia and 5 min of reperfusion during each cycle. The primary outcome was the absolute change in glomerular filtration rate (GFR) of the affected kidney by renal scintigraphy from baseline to 6 months. The secondary outcomes included urinary retinol-binding protein (RBP) levels measured at 24 and 48 h, serum creatinine, and estimated GFR (eGFR) at 1 and 6 months, and changes in GFR by renal scintigraphy.

RESULTS

There were no differences in the change of GFR of the affected kidney at 6 months, while it was significantly decreased by 15.0% in the control group vs 8.8% in the RIPC group at 1 month (P = 0.034). The urinary RBP levels increased 8.4-fold at 24 h in the control group compared with a lower increase of 3.9-fold in the RIPC group (P < 0.001). There were no differences in the serum creatinine level or eGFR at 1 and 6 months between the two groups.

CONCLUSIONS

In patients undergoing LPN, RIPC using transient lower limb ischaemia may reduce renal impairment in the short term, but failed in the longer term despite a non-significant trend in favour of RIPC. These novel data support the need for a larger study of RIPC during LPN surgery.