Skin microcirculation and regional peripheral resistance in patients with chronic renal anaemia treated with recombinant human erythropoietin

A Randomized Controlled Trial: Regenerative Effects, Efficacy and Safety of Erythropoietin in Burn and Scalding Injuries

In adult’s burn injuries belong to the top 15 causes of injury. Annually more than a million patients receive specialized treatment. Improving burned patients’ outcomes is still a challenge. Effects of erythropoietin (EPO) are reported to be pro-angiogenic, pro-regenerative, anti-inflammatory, immunomodulatory and hypoxia/ischemia protective. Study objectives were to demonstrate cytoprotective and regenerative effects of EPO in burned patients in terms of improved wound healing, reduced morbidity and mortality. This was a prospective, placebo-controlled, randomized, double-blind trial. The trial was conducted in 13 specialized burn care centers in Germany. Adult Patients with 2b° or 3° burn injuries were included. Patients received state of the art burn care including obligatory split skin graft transplantation. Study medication was EPO or placebo every other day for 21 days. Between 12/08 and 06/14, 116 patients were randomized, 84 received study medication (EPO 45, Placebo 39). Primary endpoint analysis revealed inconclusive results, as only a minority of patients reached the primary endpoint [100% re-epithelialization: EPO: 23% (9/40); Placebo 30% (11/37)]. Several secondary endpoints such as SOFA score (morbidity), EPO level in blood and wound healing onset revealed clinical, and statistically significant results in favor of the EPO group. Adverse Events (AEs) and Severe Adverse Events (SAEs) were in expected ranges; AEs EPO: 80%, (36/45), Placebo: 77%, (30/39); SAEs EPO: 24%, (11/45), Placebo: 24%, (8/39). Out of 84 patients two died, one per group, thus mortality was lower than expected. Results (SOFA score) indicate a lower morbidity of the EPO group, suggesting pro-regenerative effects of EPO in burned patients. Higher EPO levels might influence the faster onset of re-epithelialization in the first 10 days of the treatment. Both effects could reveal new therapeutic options.

Clinical Trial Registration: ISRCT Number: ISRCTN95777824 and EudraCT Number: 2006-002886-38, Protocol Number: 0506.

Erythropoietin improves skeletal muscle microcirculation and tissue bioenergetics in a mouse sepsis model

Introduction

The relationship between oxygen delivery and consumption in sepsis is impaired, suggesting a microcirculatory perfusion defect. Recombinant human erythropoietin (rHuEPO) regulates erythropoiesis and also exerts complex actions promoting the maintenance of homeostasis of the organism under stress. The objective of this study was to test the hypothesis that rHuEPO could improve skeletal muscle capillary perfusion and tissue oxygenation in sepsis.

Methods

Septic mice in three experiments received rHu-EPO 400 U/kg subcutaneously 18 hours after cecal ligation and perforation (CLP). The first experiment measured the acute effects of rHuEPO on hemodynamics, blood counts, and arterial lactate level. The next two sets of experiments used intravital microscopy to observe capillary perfusion and nicotinamide adenine dinucleotide (NADH) fluorescence post-CLP after treatment with rHuEPO every 10 minutes for 40 minutes and at 6 hours. Perfused capillary density during a three-minute observation period and NADH fluorescence were measured.

Results

rHuEPO did not have any effects on blood pressure, lactate level, or blood cell numbers. CLP mice demonstrated a 22% decrease in perfused capillary density compared to the sham group (28.5 versus 36.6 capillaries per millimeter; p < 0.001). Treatment of CLP mice with rHuEPO resulted in an immediate and significant increase in perfused capillaries in the CLP group at all time points compared to baseline from 28.5 to 33.6 capillaries per millimeter at 40 minutes; p < 0.001. A significant increase in baseline NADH, suggesting tissue hypoxia, was noted in the CLP mice compared to the sham group (48.3 versus 43.9 fluorescence units [FU]; p = 0.03) and improved with rHuEPO from 48.3 to 44.4 FU at 40 minutes (p = 0.02). Six hours after treatment with rHuEPO, CLP mice demonstrated a higher mean perfused capillary density (39.4 versus 31.7 capillaries per millimeter; p < 0.001) and a lower mean NADH fluorescence as compared to CLP+normal saline mice (49.4 versus 52.7 FU; p = 0.03).

Conclusion

rHuEPO produced an immediate increase in capillary perfusion and decrease in NADH fluorescence in skeletal muscle. Thus, it appears that rHuEPO improves tissue bioenergetics, which is sustained for at least six hours in this murine sepsis model.

Cytoprotective doses of erythropoietin or carbamylated erythropoietin have markedly different procoagulant and vasoactive activities

Recombinant human erythropoietin (rhEPO) is receiving increasing attention as a potential therapy for prevention of injury and restoration of function in nonhematopoietic tissues. However, the minimum effective dose required to mimic and augment these normal paracrine functions of erythropoietin (EPO) in some organs (e.g., the brain) is higher than for treatment of anemia. Notably, a dose-dependent risk of adverse effects has been associated with rhEPO administration, especially in high-risk groups, including polycythemia-hyperviscosity syndrome, hypertension, and vascular thrombosis. Of note, several clinical trials employing relatively high dosages of rhEPO in oncology patients were recently halted after an increase in mortality and morbidity, primarily because of thrombotic events. We recently identified a heteromeric EPO receptor complex that mediates tissue protection and is distinct from the homodimeric receptor responsible for the support of erythropoiesis. Moreover, we developed receptor-selective ligands that provide tools to assess which receptor isoform mediates which biological consequence of rhEPO therapy. Here, we demonstrate that rhEPO administration in the rat increases systemic blood pressure, reduces regional renal blood flow, and increases platelet counts and procoagulant activities. In contrast, carbamylated rhEPO, a heteromeric receptor-specific ligand that is fully tissue protective, increases renal blood flow, promotes sodium excretion, reduces injury-induced elevation in procoagulant activity, and does not effect platelet production. These preclinical findings suggest that nonerythropoietic tissue-protective ligands, which appear to elicit fewer adverse effects, may be especially useful in clinical settings for tissue protection.

Haemodynamic changes measured by transthoracic bioimpedance during treatment with recombinant human erythropoietin

Hypertension complicates the treatment of anaemia of chronic renal failure with recombinant human erythropoietin (EPO) in some patients. We conducted a prospective study measuring changes in cardiac index (CI) and systemic vascular resistance index (SVRI) in 29 patients from before commencement of EPO to attainment of target haemoglobin concentration. We used the operator-independent technique of trans-thoracic bioimpedance. The group of patients who developed EPO-induced hypertension (EpHT) were separately analysed and compared with the group who had no change in blood pressure (NC). Our results showed there was a significant rise in SVRI after treatment in EpHT group patients but in the NC group there was a small fall. CI increased significantly in the NC group after treatment but no change was recorded in the EpHT group. These findings clearly demonstrate how the cardiovascular changes differ in patients who develop EPO-induced hypertension.

Effects of oxygen breathing and erythropoietin on hypoxic vasodilation in uremic anemia

Loss of hypoxic vasodilation has been proposed as a causative factor in the development of hypertension in dialysis patients treated with recombinant human erythropoietin (rHuEPO). Venous occlusion plethysmography was therefore performed on 22 dialysis patients (aged 23 to 71 years, dialysis duration 6 to 260 months, 8 males) before and after correction of anemia with rHuEPO, 50 U/kg 3x/week (Hb: 7.4 +/- 0.3 vs. 10.8 +2- 0.3 g/dl, P less than 0.0001). Hypertension (greater than 15 mm Hg rise in mean BP) occurred in 11 patients. The study was performed while breathing room air and repeated after breathing 60% O2 for 10 to 12 minutes. Before rHuEPO therapy, total blood O2 content increased from 10.01 +/- 0.39 to 10.32 +/- 0.29 ml O2/100 ml blood with breathing 60% O2 (P less than 0.01). After correction of anemia it was 14.65 +/- 0.40 ml O2/100 ml blood on room air (P less than 0.001). There was a significant decrease in forearm blood flow (7.9 +/- 0.5 vs. 6.5 +/- 0.6 ml/min/100 ml tissue, P less than 0.05) and increase in forearm vascular resistance (12.8 +/- 0.1 vs. 16.8 +/- 0.2 mm Hg/ml/min/100 ml tissue, P less than 0.05) with O2 breathing prior to rHuEPO therapy in the blood pressure responders, but no change in these parameters in the group in which blood pressure remained unchanged. When all patients were studied on room air, forearm vascular resistance rose significantly after correction of anemia (13.0 +/- 0.8 vs. 16.3 +/- 0.8 mm Hg/ml/min/100 ml tissue, P less than 0.05), compared with that prior to rHuEPO therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in middle cerebral artery blood velocity in uremic patients after hemodialysis

BACKGROUND AND PURPOSE

Strokes are a frequent complication in uremic patients on dialysis. We wanted to evaluate the effect of this treatment on cerebral hemodynamic parameters, particularly those of patients with carotid stenosis, who are at higher risk for atherothrombotic ischemic events.

METHODS

We used transcranial Doppler ultrasonography to evaluate blood velocity of the middle cerebral artery in 18 uremic patients before and after hemodialysis. Carotid stenosis was evaluated by echo-Doppler investigation. Six patients were also studied before and after recombinant human erythropoietin treatment.

RESULTS

Dialysis treatment decreased mean blood velocity in all patients (p less than 0.001). Eight of 18 patients (44%) with mild (16-50%), moderate (51-80%), or severe (greater than 80%) carotid stenosis had lower velocity than patients with normal carotid arteries (p less than 0.01), and they experienced a further decrease to even lower levels after hemodialysis (p less than 0.05). In patients treated with recombinant human erythropoietin, hematocrit increased from 28 +/- 8% to 37 +/- 5% (p less than 0.001), and blood velocity had a further decrease by 11%. All changes were associated with modifications toward normality of pH, PaCO2, and hematocrit.

CONCLUSIONS

Transcranial Doppler ultrasonography represents a useful method for monitoring cerebral circulation of uremic patients, especially of those at possible risk for ischemia.