New Applications of HBOC-201: A 25-Year Review of the Literature

If not cured promptly, tissue ischemia and hypoxia can cause serious consequences or even threaten the life of the patient. Hemoglobin-based oxygen carrier-201 (HBOC-201), bovine hemoglobin polymerized by glutaraldehyde and stored in a modified Ringer's lactic acid solution, has been investigated as a blood substitute for clinical use. HBOC-201 was approved in South Africa in 2001 to treat patients with low hemoglobin (Hb) levels when red blood cells (RBCs) are contraindicated, rejected, or unavailable. By promoting oxygen diffusion and convective oxygen delivery, HBOC-201 may act as a direct oxygen donor and increase oxygen transfer between RBCs and between RBCs and tissues. Therefore, HBOC-201 is gradually finding applications in treating various ischemic and hypoxic diseases including traumatic hemorrhagic shock, hemolysis, myocardial infarction, cardiopulmonary bypass, perioperative period, organ transplantation, etc. However, side effects such as vasoconstriction and elevated methemoglobin caused by HBOC-201 are major concerns in clinical applications because Hbs are not encapsulated by cell membranes. This study summarizes preclinical and clinical studies of HBOC-201 applied in various clinical scenarios, outlines the relevant mechanisms, highlights potential side effects and solutions, and discusses the application prospects. Randomized trials with large samples need to be further studied to better validate the efficacy, safety, and tolerability of HBOC-201 to the extent where patient-specific treatment strategies would be developed for various clinical scenarios to improve clinical outcomes.

Cholecystokinin-8 treatment reduces acinar necrosis and edema of pigs with induced pancreatitis

BACKGROUND

Acute pancreatitis is an inflammatory process of the pancreas and a leading cause of hospitalization amongst gastrointestinal disorders. Previously, cholecystokinin (CCK) has been described to play a role in regeneration of pancreas. The aim of this study was to analyse the function of cholecystokinin octapeptide (CCK-8) during induced pancreatitis in an animal model.

METHODS

Overall acute pancreatitis was induced in 38 pigs. After the induction of acute pancreatitis, half of the animals were treated with CCK-8. Intraoperative clinical data, postoperative blood parameters, 'Porcine Well-being' (PWB) and fitness score and post-mortal histopathological data were analysed.

RESULTS

At baseline, physiologically parameters of the pigs of both groups were comparable. No differences were observed regarding the overall survival of animals (p = 0.97). Postoperative PWB score were significantly enhanced in animals treated with CCK-8 as compared to the control group (p = 0.029). Moreover, histopathological analysis of the pancreatic tissue revealed that acinar necrosis and edema were significant reduced in the CCK-8 group in comparison to the control group (p = 0.016 and p = 0.019).

CONCLUSIONS

In conclusion, we found that CCK-8 treatment reduces acinar necrosis and edema of pancreatic tissue after induction of an acute pancreatitis in pigs.

The Effects of Pancreatic Microcirculatory Disturbances on Histopathologic Tissue Damage and the Outcome in Severe Acute Pancreatitis

OBJECTIVES

Severe acute pancreatitis is an inflammatory disease of the pancreas with a high morbidity and mortality. To date, no causal treatment is known. The aim of the present study was to analyze the impact of pancreatic microcirculatory disturbances in severe acute pancreatitis and to correlate the effects with histopathologic tissue damage and outcome.

METHODS

Severe acute pancreatitis was induced in 129 pigs by injection of glycodeoxycholic acid into the pancreatic duct. Pancreatic microcirculation, pancreatic tissue oxygenation, histopathologic tissue damage, and survival were measured and analyzed.

RESULTS

Our study demonstrates a strong correlation between pancreatic microcirculatory disturbances and histopathologic tissue damage (r = 0.728; P < 0.001). Furthermore, we showed a strong correlation between tissue oxygenation and the severity of the pancreatitis according to an established porcine pancreatitis score (r = 0.694; P < 0.001). In addition, disturbances of the pancreatic microcirculation were shown to be associated with an increased mortality rate in severe acute pancreatitis.

CONCLUSIONS

We found that pancreatic microcirculatory disturbances have significant effects on histopathologic tissue damage and the outcome of severe acute pancreatitis. For a better survival of severe acute pancreatitis, the treatment should focus on an improvement of pancreatic microcirculation.

Effects of hydroxyethyl starch and cell-free hemoglobin on microcirculation, tissue oxygenation, and survival in severe acute porcine pancreatitis: results of a randomized experimental trial

OBJECTIVE

Severe acute pancreatitis is a life-threatening disease with a high mortality; so far, no causal treatment is known. The aim of this study was to evaluate the therapeutic potential of hydroxyethyl starch (HES) and cell-free hemoglobin in an experimental model.

METHODS

Thirty-nine pigs were randomly assigned into 3 groups. Severe acute pancreatitis was induced by intraductal injection of glycodeoxycholic acid in combination with intravenous administration of cerulein. All animals were kept in isovolemic conditions by application of Ringer solution, 10% HES, or cell-free hemoglobin. The pancreatic microcirculation was evaluated over 8 hours. Thereafter, the animals were observed for 6 days followed by killing of the animals and histopathologic examination.

RESULTS

The administration of HES and cell-free hemoglobin led to improved microcirculation and tissue oxygenation compared with the Ringer's group. Consequently, the histopathologic damage was reduced (5.5 [3-8.5] vs 9.5 [7.5-11]; P < 0.001). In addition, the mean survival was significantly longer at 121 hours (95% confidence interval, 102-139) versus the Ringer group's 57 hours (95% confidence interval, 32-82; P < 0.001).

CONCLUSIONS

The administration of HES and cell-free hemoglobin can improve microcirculation in severe acute porcine pancreatitis, with consequent reduction in histopathologic damage and mortality. Therefore, this might represent an interesting therapeutic option in the treatment of severe acute pancreatitis.

The effects of decreasing low-molecular weight hemoglobin components of hemoglobin-based oxygen carriers in swine with hemorrhagic shock

BACKGROUND

Some hemoglobin-based oxygen carriers (HBOCs) improve outcome in animal models of hemorrhagic shock (HS) in comparison with standard asanguinous resuscitation fluids. Nevertheless, concern about intrinsic vasoactivity, linked in part to low-molecular weight (MW) hemoglobin (Hb), has slowed HBOC development. We assessed the impact of decreasing the low-MW Hb component of bovine HBOC on vasoactivity in severe HS.

METHODS

Anesthetized invasively monitored swine were hemorrhaged 55% blood volume and resuscitated with bovine HBOC containing 31% (31 TD [HBOC-301]), 2% (2 TD [HBOC-201]), or 0.4% (0.4 TD) low-MW Hb. Pigs received four 10 mL/kg infusions over 60 minutes, hospital arrival was simulated at 75 minutes, organ blood flow (BF) was evaluated by microsphere injection, and monitoring was continued for 4 hours followed by complete necrotic evaluation.

RESULTS

There were few differences between 2 TD and 0.4 TD. Thirty-one TD pigs had higher systemic and pulmonary blood pressure (BP), systemic vascular resistance index, and pulmonary artery wedge pressure, compared with 2 TD or 0.4 TD (p < 0.01); however, pigs in all groups had at least mildly elevated BP. Transcutaneous tissue oxygenation, base excess, and mixed venous oxygen saturation were similar across groups; lactate and methemoglobin were highest with 0.4 TD (p < 0.03). There were no group differences in BF. Over time, myocardial BF increased and hepatic BF decreased in all groups (for 31 TD, p < 0.05); renal BF was unchanged in all groups. There were no group differences in heart, lung, or liver histopathology, and survival.

CONCLUSIONS

Although purification from 31% to 2% low-MW Hb content significantly decreased vasoactive responses, further purification to 0.4% had no additional clinically measurable effects in severe HS. If further diminution in HBOC vasoactivity is desired for use in HS, additional technical approaches may be required.

Use of hemoglobin-based oxygen-carrying solution-201 to improve resuscitation parameters and prevent secondary brain injury in a swine model of traumatic brain injury and hemorrhage: laboratory investigation

OBJECT

Traumatic brain injury (TBI) often occurs as part of a multisystem trauma that may lead to hemorrhagic shock. Effective resuscitation and restoration of oxygen delivery to the brain is important in patients with TBI because hypotension and hypoxia are associated with poor outcome in head injury. We studied the effects of hemoglobin-based oxygen-carrying (HBOC)-201 solution compared with lactated Ringer (LR) solution in a large animal model of brain injury and hemorrhage, in a blinded prospective randomized study.

METHODS

Swine underwent brain impact injury and hemorrhage to a mean arterial pressure (MAP) of 40 mm Hg. Twenty swine were randomized to undergo resuscitation with HBOC-201 (6 ml/kg) or LR solution (12 ml/kg) and were observed for an average of 6.5 +/- 0.5 hours following resuscitation. At the end of the observation period, magnetic resonance (MR) imaging was performed. Histological studies of swine brains were performed using Fluoro-Jade B, a marker of early neuronal degeneration.

RESULTS

Swine resuscitated with HBOC-201 had higher MAP, higher cerebral perfusion pressure (CPP), improved base deficit, and higher brain tissue oxygen tension (PbtO(2)) than animals resuscitated with LR solution. No significant difference in total injury volume on T2-weighted MR imaging was observed between animals resuscitated with HBOC-201 solution (1155 +/- 374 mm(3)) or LR solution (1246 +/- 279 mm(3); p = 0.55). On the side of impact injury, no significant difference in the mean number of Fluoro-Jade B-positive cells/hpf was seen between HBOC-201 solution (61.5 +/- 14.7) and LR solution (48.9 +/- 17.7; p = 0.13). Surprisingly, on the side opposite impact injury, a significant increase in Fluoro-Jade B-positive cells/hpf was seen in animals resuscitated with LR solution (42.8 +/- 28.3) compared with those resuscitated with HBOC-201 solution (5.6 +/- 8.1; p < 0.05), implying greater neuronal injury in LR-treated swine.

CONCLUSIONS

The improved MAP, CPP, and PbtO(2) observed with HBOC-201 solution in comparison with LR solution indicates that HBOC-201 solution may be a preferable agent for small-volume resuscitation in brain-injured patients with hemorrhage. The use of HBOC-201 solution appears to decrease cellular degeneration in the brain area not directly impacted by the primary injury. Hemoglobin-based oxygen-carrying-201 solution may act by improving cerebral blood flow or increasing the oxygen-carrying capacity of blood, mitigating a second insult to the injured brain.

Resuscitation from hemorrhagic shock comparing standard hemoglobin-based oxygen carrier (HBOC)-201 versus 7.5% hypertonic HBOC-201

BACKGROUND

Hemoglobin-based oxygen carrier (HBOC) resuscitation has been associated with increased systemic and pulmonary vascular resistances (SVR, PVR), which may result in reduced blood flow and severe pulmonary hypertension. The physiologic and immunologic properties of 7.5% hypertonic saline solution (HTS), such as reduction of SVR and PVR, as well as inhibition of neutrophil and endothelial activation may be beneficial in reducing some of these undesirable effects of HBOCs. The aim of this study was to evaluate the hemodynamic effects of the HBOC and HBOC-201 suspended in 7.5% hypertonic saline solution (HT-HBOC) when compared with standard HBOC resuscitation.

METHODS

Thirty-two domestic crossbred pigs (50-60 kg) were hemorrhaged to a mean arterial pressure (MAP) of 35 mm Hg +/- 5 mm Hg for 45 minutes and resuscitated to a baseline mean arterial pressure using the following groups: (1) sham, no hemorrhage; (2) shed blood + lactated Ringer's solution; (3) standard HBOC-201; (4) hypertonic saline 7.5%; (5) hypertonic 7.5% HBOC-201. After resuscitation, observation was continued for 4 hours. Hemodynamic variables, oxygen consumption, and arterial blood gases were monitored continuously. Data were analyzed using analysis of variance.

RESULTS

SVR (p = 0.001), PVR (p = 0.001), and MPAP (p = 0.01) were significantly reduced in the HT-HBOC group compared with the standard HBOC group.

CONCLUSION

In this model of hemorrhagic shock, hypertonic HBOC-201- resuscitated pigs had significantly reduced SVR and PVR, as well as mean pulmonary artery pressure (MPAP) and increased cardiac output. HT-HBOC may be beneficial in reducing the undesirable effects of standard HBOC-201. The mechanisms of these beneficial effects need to be investigated.