Artificial Oxygen Carrier With Pharmacologic Actions of Adenosine‐5′‐Triphosphate,Adenosine, and Reduced Glutathione Formulated to Treat an Array of Medical Conditions

Effective artificial oxygen carriers may offer a solution to tackling current transfusion medicine challenges such as blood shortages, red blood cell storage lesions, and transmission of emerging pathogens. These products, could provide additional therapeutic benefits besides oxygen delivery for an array of medical conditions. To meet these needs, we developed a hemoglobin (Hb)‐based oxygen carrier, HemoTech, which utilizes the concept of pharmacologic cross‐linking. It consists of purified bovine Hb cross‐linked intramolecularly with open ring adenosine‐5′‐triphosphate (ATP) and intermolecularly with open ring adenosine, and conjugated with reduced glutathione (GSH). In this composition, ATP prevents Hb dimerization, and adenosine promotes formation of Hb polymers as well as counteracts the vasoconstrictive and pro‐inflammatory properties of Hb via stimulation of adenosine receptors. ATP also serves as a regulator of vascular tone through activation of purinergic receptors. GSH blocks Hb's extravasation and glomerular filtration by lowering the isoelectric point, as well as shields heme from nitric oxide and reactive oxygen species. HemoTech and its manufacturing technology have been broadly tested, including viral and prion clearance validation studies and various nonclinical pharmacology, toxicology, genotoxicity, and efficacy tests. The clinical proof‐of‐concept was carried out in sickle cell anemia subjects. The preclinical and clinical studies indicate that HemoTech works as a physiologic oxygen carrier and has efficacy in treating: (i) acute blood loss anemia by providing a temporary oxygen bridge while stimulating an endogenous erythropoietic response; (ii) sickle cell disease by counteracting vaso‐occlusive/inflammatory episodes and anemia; and (iii) ischemic vascular diseases particularly thrombotic and restenotic events. The pharmacologic cross‐linking of Hb with ATP, adenosine, and GSH showed usefulness in designing an artificial oxygen carrier for multiple therapeutic indications.     

Preclinical In Vitro Safety Investigations of Submicron Sized Hemoglobin Based Oxygen Carrier HbMP‐700

Hemoglobin‐based oxygen carriers (HBOCs) are being developed as oxygen and plasma volume‐expanding therapeutics though their potential to promote oxidative tissue injury and nitric oxide (NO) scavenging combined with vasoconstriction has raised safety concerns. Therefore, we focused on these aspects during preclinical studies performed with the recently introduced hemoglobin microparticles (HbMP‐700). Besides oxidative stress, we investigated possible vasoconstrictory influence of HBOCs as well as genetic toxicity. The novel developed HbMP‐700 presented here provides a high oxygen affinity which prevents premature oxygen oversupply and avoids vasoconstriction of small blood vessels in vitro. The size of these particles is 700 nm (larger than 100 nm and smaller than 1000 nm) in order to prevent penetration through the blood vessel's endothelial gaps, NO‐scavenging, and to avoid phagocytosis of large particles. We expect that the HbMP‐700 meets the sophisticated requirements as a universal blood substitute.     

Danshen‐Enhanced Cardioprotective Effect of Cardioplegia on Ischemia Reperfusion Injury in a Human‐Induced Pluripotent Stem Cell‐Derived Cardiomyocytes Model

Myocardial ischemia‐reperfusion (I/R) injury is unavoidable during cardioplegic arrest and open‐heart surgery. Danshen is one of the most popular traditional herbal medicines in China, which has entered the Food and Drug Administration‐approved phase III clinical trial. This study was aimed to develop a human‐induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) model to mimic I/R injury and evaluate the cardioprotective effect of regular cardioplegic solution with Danshen. hiPSC‐CMs were cultured with the crystalloid cardioplegic solution (Thomas group) and Thomas solution with 2 or 10 µg/mL Danshen (Thomas plus Danshen groups). The cells under normoxic culture condition served as baseline group. Then, the cells were placed in a modular incubator chamber. After 45 min hypoxia and 3 h reoxygenation, hiPSC‐CMs subjected to hypoxia/reoxygenation resulted in a sharp increase of reactive oxygen species (ROS) content in Thomas group versus baseline group. Compared with the Thomas group, ROS accumulation was significant suppressed in Thomas plus Danshen groups, which might result from elevating the content of glutathione and enhanced activities of superoxide dismutase and glutathione peroxidase. The enhanced L‐type Ca²⁺ current in hiPSC‐CMs after I/R injury was also significantly decreased by Danshen, and meanwhile intracellular Ca²⁺ level was reduced and calcium overload was suppressed. Thomas plus Danshen groups also presented less irregular transients and lower apoptosis rates. As a result, Danshen could improve antioxidant and calcium handling in cardiomyocytes during I/R and lead to reduced arrhythmia events and apoptosis rates. hiPSC‐CMs model offered a platform for the future translational study of the cardioplegia.     

PEGylated Carboxyhemoglobin Bovine (SANGUINATE): Results of a Phase I Clinical Trial

PEGylated carboxyhemoglobin bovine (SANGUINATE) is a dual action carbon monoxide releasing (CO)/oxygen (O₂) transfer agent for the treatment of hypoxia. Its components inhibit vasoconstriction, decrease extravasation, limit reactive oxygen species production, enhance blood rheology, and deliver oxygen to the tissues. Animal models of cerebral ischemia, peripheral ischemia, and myocardial ischemia demonstrated SANGUINATE's efficacy in reducing myocardial infarct size, limiting necrosis from cerebral ischemia, and promoting more rapid recovery from hind limb ischemia. In a Phase I trial, three cohorts of eight healthy volunteers received single ascending doses of 80, 120, or 160 mg/kg of SANGUINATE. Two volunteers within each cohort served as a saline control. There were no serious adverse events. Serum haptoglobin decreased, but did not appear to be dose related. The T_1/2 was dose dependent and ranged from 7.9 to 13.8 h. In addition to the Phase I trial, SANGUINATE was used under an expanded access emergency Investigational New Drug. SANGUINATE was found to be safe and well tolerated in a Phase I clinical trial, and therefore it will advance into further clinical trials in patients.     

Hydrogen Gas Does Not Ameliorate Renal Ischemia Reperfusion Injury in a Preclinical Model

In renal transplantation, ischemia reperfusion injury impairs early graft function and can reduce long term graft survival. Hydrogen has antioxidant and anti‐inflammatory properties that can reduce the effects of ischemic injury. The aim of this study was to examine the effects of hydrogen gas administered during reperfusion in a preclinical model of kidney ischemia reperfusion injury. Porcine kidneys underwent 15 min of warm ischemia followed by 22 h of cold ischemia. They were then reperfused for 6 h with whole autologous blood on an ex vivo reperfusion circuit. Paired kidneys were randomized to control (n = 6) (25% oxygen, 5% carbon dioxide, 70% nitrogen) or hydrogen (n = 6) (2% hydrogen, 25% oxygen, 5% carbon dioxide, 68% nitrogen) groups. Tissue, urine, and blood samples were collected at baseline and hourly throughout the reperfusion period. Baseline measurements were similar across groups. Following perfusion, there was no significant difference between control and hydrogen groups in urine output (693 mL vs. 608 mL, P = 0.86), renal blood flow (105.9 vs. 108 mL/min/100g, P = 0.89), acid‐base homeostasis, or creatinine clearance. There was a significant increase in cytokine levels from baseline to 6 h in both groups (IL‐1β P = 0.002; IL‐6 P = 0.004; IL‐8 P = 0.002). However, there were no significant differences in levels of inflammatory cytokines (IL1β, IL‐6, and IL‐8) between the groups. The administration of hydrogen gas did not improve renal function, reduce oxidative damage, or inflammation during the reperfusion of ischemically damaged kidneys.     

Microcirculatory derangements in acute pancreatitis

During the past decade, a considerable number of experimental studies have confirmed the hypothesis that microcirculatory derangements play a pivotal role in the pathogenesis of acute pancreatitis, including the process of conversion from edematous to necrotizing injury. Predominant microcirculatory disorders are nutritive capillary perfusion failure, with the consequence of prolonged focal hypoxia or anoxia, and inflammation-associated microvascular leukocyte recruitment, CD11b- and intercellular adhesion molecule (ICAM)-1-mediated leukocyte-endothelial cell interaction and loss of endothelial integrity, which may result in both edema formation and necrosis. A variety of proinflammatory mediators, such as oxygen radicals, leukotrienes, platelet-activating factor, and interleukins, but also bradykinin and endothelins, seem to be involved in triggering the manifestations of these microcirculatory disorders. In contrast, the anti-inflammatory interleukin-10, as well as nitric oxide, are thought to be capable of protecting from these pancreatitis-associated microvascular injuries. This knowledge may be encouraging for the development of novel therapeutic strategies, aiming at the attenuation of microcirculatory disorders, and, thus, preventing tissue injury in acute pancreatitis. Received: July 4, 2000 / Accepted: December 28, 2000     

The Nephroprotective Properties of Recombinant Human Erythropoietin in Kidney Transplantation: Experimental Facts and Clinical Proofs

Adaptive responses to hypoxia, including hypoxia‐inducible factor signaling, allow the cell to satisfy its basal metabolic demand and avoid death, but these responses can also be deleterious by promoting inflammation, cell dedifferentiation and fibrogenesis. Therefore, targeting hypoxia constitutes a promising therapeutic avenue. Recombinant human erythropoietin (rhEPO) appeared as a good candidate therapy because its hematopoietic properties could reverse anemia, and its tissue‐protective properties could reduce cell death and limit maladaptive cellular responses to hypoxia. Despite experimental evidence on the nephroprotecive properties of rhEPO, recent clinical trials provided evidence that rhEPO was ineffective in preventing delayed graft function after ischemic acute injury but that the normalization of hemoglobin values preserved kidney function deterioration and reduced graft loss. Our aim here is to provide a survey of the rationale for evaluating the administration of rhEPO in the setting of kidney transplantation. We will discuss the intriguing findings that emerged from the clinical trials and the discrepancies between promising experimental results and negative clinical studies, as well as the differences in terms of the benefits and safety profiles of the normalization of hemoglobin values in chronic kidney disease patients and kidney transplant patients.     

The Roles of Continuous Renal Replacement Therapy in Septic Acute Kidney Injury

Despite hundreds of clinical and basic studies that have led to a better mechanistic understanding of sepsis, the number of cases with sepsis in the United States is still rising. Sepsis is a common cause of acute kidney injury (AKI) and may explain long‐term complications and mortality. In the current article, a new therapeutic concept using continuous renal replacement therapy to prevent and manage long‐term sequelae in septic AKI is described.     

Mechanical Circulatory Support Devices for Pediatric Patients With Congenital Heart Disease

The use of mechanical circulatory support (MCS) devices is a viable therapeutic treatment option for patients with congestive heart failure. Ventricular assist devices, cavopulmonary assist devices, and total artificial heart pumps continue to gain acceptance as viable treatment strategies for both adults and pediatric patients as bridge‐to‐transplant, bridge‐to‐recovery, and longer‐term circulatory support alternatives. We present a review of the current and future MCS devices for patients having congenital heart disease (CHD) with biventricular or univentricular circulations. Several devices that are specifically designed for patients with complex CHD are in the development pipeline undergoing rigorous animal testing as readiness experiments in preparation for future clinical trials. These advances in the development of new blood pumps for patients with CHD will address a significant unmet clinical need, as well as generally improve innovation of the current state of the art in MCS technology.     

Erythropoietin and progression of CKD

In patients with primary as well as secondary chronic kidney disease (CKD), anemia has been identified as an independent risk factor for progression. In these patients anemia is thought to be a surrogate parameter for tissue hypoxia that perpetuates preexisting renal tissue injury, and treatment of anemia with recombinant human erythropoietin (rHuEPO) was therefore expected to retard progression. However, results of recently published large trials in patients with CKD did not fulfill these expectations. The reason for the discrepant findings may be distinct molecular pathways and/or EPO tissue receptor affinities that mediate the effect of EPO on erythropoiesis and tissue protection by EPO. A pivotal intracellular pathway is the activation of Akt (i.e., serine/threonine protein kinase B), but further potential pathways have been identified that may play an important role in tissue protection. In this study, we review data on the non-hematological effects of rHuEPO in different experimental settings of acute and chronic kidney injury, and discuss clinical renoprotective strategies with rHuEPO or analogue substances that are not related to anemia correction.     

From Molds and Macrophages to Mevalonate: A Decade of Progress in Understanding the Molecular Mode of Action of Bisphosphonates

Although bisphosphonates were first used as therapeutic agents to inhibit bone resorption in the early 1970s, their mode of action at the molecular level has only become fully clear within the last few years. One of the reasons for this lack of understanding was the difficulty in isolating large numbers of pure osteoclasts for biochemical studies. In the last decade, the identification of appropriate surrogate models that reflected the antiresorptive potencies of bisphosphonates, such as Dictyostelium slime molds and macrophages, helped overcome this problem and proved to be instrumental in elucidating the molecular pathways by which these compounds inhibit osteoclast-mediated bone resorption. This brief review summarizes our current understanding of these pathways.     

贫血与脑损伤：问题多，答案少

大量临床研究显示围手术期患者的脑损伤与急性贫血有关。这种损伤发生在接近于我们普遍认同的输血指征[血红蛋白（Hb）浓度7～8g/dl],但高于脑组织缺氧的血红蛋白浓度（Hb3～4g／dl）的情况下。但是,贫血引起脑损伤的缺氧和非缺氧机制仍不清楚。此外,能最大程度降低急性贫血所致脑损伤的保护性机制仍未阐明。包括一氧化氮（NO）在内的血管扩张机制,在贫血时有助于维持大脑氧供,在各种急性稀释性缺血试验模型中,3种NO合成酶（NOS）（神经型、内皮型及可诱导型NOS）都有上调。近来的实验也证实了在相当于临床缺氧Hb浓度（Hb6—7g/dl）的啮齿类动物的大脑皮质中,重要的转录因子如缺氧诱导因子（HIF）-1α有所增加。这说明急性贫血对脑氧的供需平衡可能造成威胁,在缺氧的情况下,细胞浆中的HIF-1α降解被抑制,HIF-1α积聚成二聚体,移位到细胞核中并增加许多低氧分子的转录。这些低氧分子在贫血的脑组织中的表达也被发现上调,包括红细胞生成素,血管内皮生长因子,可诱导型NOS。此外,非低氧介质,包括细胞因子和血管激素,可以增加HIF-1α的转录。而且,源于NOS的NO也可以在没有组织缺氧时稳定HIF—1α。因此,在贫血时,HIF-1α在低氧和常氧情况下能对脑细胞进行调节。实验研究发现,针对不同类型的细胞,上调的HIF-1α可以表现为神经保护作用或神经毒性作用。在本综述中,我们描述了这些细胞作用过程,对贫血引起的脑损伤和保护机制有了更清晰的认识。贫血引起损伤的可能机制包括脑栓塞、组织缺氧、炎症、活性氧和兴奋性毒性。可能的细胞保护机制包括NOS／NO依赖的细胞氧供增强和包括HIF-1α、红细胞生成素及血管内皮生长因子在内的细胞保护机制。这些激活的细胞机制的总体平衡决定着它们在贫血时的?     

Low Tidal Volume Reduces Lung Inflammation Induced by Liquid Ventilation in Piglets With Severe Lung Injury

Total liquid ventilation (TLV) is an alternative treatment for severe lung injury. High tidal volume is usually required for TLV to maintain adequate CO₂ clearance. However, high tidal volume may cause alveolar barotrauma. We aim to investigate the effect of low tidal volume on pulmonary inflammation in piglets with lung injury and under TLV. After the establishment of acute lung injury model by infusing lipopolysaccharide, 12 piglets were randomly divided into two groups, TLV with high tidal volume (25 mL/kg) or with low tidal volume (6 mL/kg) for 240 min, respectively. Extracorporeal CO₂ removal was applied in low tidal volume group to improve CO₂ clearance and in high tidal volume group as sham control. Gas exchange and hemodynamic status were monitored every 30 min during TLV. At the end of the study, pulmonary mRNA expression and plasmatic concentration of interleukin‐6 (IL‐6) and interleukin‐8 (IL‐8) were measured by collecting lung tissue and blood samples from piglets. Arterial blood pressure, PaO₂, and PaCO₂ showed no remarkable difference between groups during the observation period. Compared with high tidal volume strategy, low tidal volume resulted in 76% reduction of minute volume and over 80% reduction in peak inspiratory pressure during TLV. In addition, low tidal volume significantly diminished pulmonary mRNA expression and plasmatic level of IL‐6 and IL‐8. We conclude that during TLV, low tidal volume reduces lung inflammation in piglets with acute lung injury without compromising gas exchange.     

Hypoxia--a key regulator of angiogenesis and inflammation in rheumatoid arthritis

The importance of inflammation in rheumatoid arthritis (RA) is well understood. This knowledge has resulted in the development of anti-inflammatory therapies--either broadly acting (such as steroids) or more specific approaches (such as antibodies against TNF)--with biologic therapies (including TNF inhibitors) revolutionizing the treatment of RA. However, what is less well appreciated in RA are the links between inflammation, blood-vessel formation (angiogenesis) and cellular responses to changes in oxygen tension. Inadequate oxygenation, termed hypoxia, is thought to drive the increase in synovial angiogenesis that occurs in RA, through expression of hypoxia-inducible molecules, including vascular endothelial growth factor (VEGF). This process promotes further infiltration of inflammatory cells and production of inflammatory mediators, perpetuating synovitis. This Review highlights the molecular pathways activated by hypoxia, and how these pathways might interact with inflammatory signaling to promote and maintain synovitis in RA, with a particular focus on the response of macrophages to hypoxia in the context of RA. Successful treatment of RA, for example with anti-TNF antibodies, reduces levels of proangiogenic factors, including VEGF, and leads to normalization of the vasculature. These processes emphasise the close links between hypoxia, angiogenesis and inflammation in this disease and supports the concept that angiogenesis blockade could be of therapeutic benefit in RA.     

Management of priapism in a child with sickle cell anemia; successful outcome using epidural analgesia

PURPOSE: To describe the successful management of priapism secondary to sickle cell anemia in a child using neuraxial analgesia provided via an epidural catheter. CLINICAL FEATURES: A seven-year-old male presented with chest crisis and priapism which, following hemoglobin electrophoresis led to a new diagnosis of sickle cell anemia. Epidural management was attempted as an alternative to surgery after failure of more conventional medical and surgical methods to treat the priapism. The patient's clinical condition improved with this intervention and together with further conservative therapy resulted in complete resolution of the priapism. CONCLUSIONS: Priapism is a well described complication of sickle cell anemia that is painful and difficult to manage. Surgical intervention is the last therapeutic resort and often results in significant long-term morbidity. This case highlights how select cases of priapism can be successfully managed with epidural neuraxial blockade which not only provides superior analgesia for the often painful conservative treatments, but may also per se impart a direct and salutary therapeutic benefit.     

Advances in secondary spinal cord injury: role of apoptosis

The outcome of spinal cord injury depends on the extent of secondary damage produced by a series of cellular and molecular events initiated by the primary trauma. This article reviews the evidence that secondary spinal cord injury involves the apoptotic as well as necrotic death of neurons and glial cells. Also discussed are the major factors that can contribute to cell death, such as glutamatergic excitotoxicity, free radical damage, cytokines, and inflammation. The development of innovative therapeutic strategies to reduce secondary spinal cord injury depends on an increased understanding of secondary injury mechanisms at the molecular and biochemical level. Such therapeutic interventions may include the use of antiapoptotic drugs, free radical scavengers, and anti-inflammatory agents. These could be targeted to block key reactions on cellular and molecular injury cascades, thus reducing secondary tissue damage, minimizing side effects, and improving functional recovery.     

Effect of Anemia on Prognosis in Patients on Extracorporeal Membrane Oxygenation

Anemia is a component of the pathological triangle in cardiorenal anemia syndrome and is a risk factor for mortality in acute respiratory distress syndrome. This study assessed the predictive value of anemia for outcomes in critically ill patients receiving extracorporeal membrane oxygenation (ECMO) support. This retrospective study analyzed patients who received ECMO support at the cardiovascular surgery intensive care unit in the study institute between July 2003 and March 2012. Patient data, such as demographic information, etiologies of ECMO implementation, clinical parameters, and in‐hospital and 6‐month mortality rates, were statistically analyzed. The overall in‐hospital mortality rate among the enrolled 295 patients was 55.6%. Multivariate logistical regression analysis indicated that age, albumin levels, sequential organ failure assessment (SOFA) score, and hemoglobin (Hb) level on ECMO day 1 exhibited independent prognostic significance for predicting in‐hospital mortality rate. The SOFA score exhibited the highest areas under the receiver operating characteristic curve value (0.812 ± 0.025). The Hb level on ECMO day 1 exhibited satisfactory calibration and discriminatory power. The cumulative 6‐month survival rates differed significantly between patients with Hb levels less than and more than 8.85 g/dL (30.6 vs. 54.0%, respectively, P < 0.001). This study indicated that old age, low albumin levels, low Hb levels, and higher SOFA scores on ECMO day 1 increased the risk of mortality. The Hb level is a readily measurable parameter and with good predictive power for critical patients on ECMO.