Endothelial accumulation of hydroxyethyl starch and functional consequences on leukocyte-endothelial interactions

Effects of hydroxyethyl starch (HES 130/0.42) on endothelial and epithelial permeability in vitro

Hydroxyethyl starch (HES) is employed to sustain normovolemia in patients. Using a perfused organ model, we recently showed that HES impairs the intestinal barrier which is constituted of endothelial and epithelial cell layers. However, the target cells and molecular actions of HES in the intestine are mainly unknown. Employing a model of human endothelial (HUVEC) and intestinal epithelial cells (Caco-2), we investigated the impact of HES, albumin and HES/albumin on cellular integrity/permeability and evaluated underlying molecular mechanisms. Monolayers of HUVEC and Caco-2 were cultured with HES (3%), albumin (3%) or HES/albumin (1.5%/1.5%). Integrity and permeability of the cell layers were evaluated by FITC-dextran transfer, measurements of cell detachment, vitality, cell volume, LDH release and caspase-3/7 activity. Cellular mechanisms were analyzed by Westernblotting for P-akt, P-erk, claudin-3 and I-FABP. HES application resulted in higher numbers of non-adherent/floating HUVEC cells (P<0.05) but did not change vitality or cell volume. Both, HES and HES/albumin increased the permeability of HUVEC monolayers (P<0.001), while LDH release, caspase-3/7 activity, akt/erk phosphorylation and claudin-3 expression were not affected. HES and HES/albumin did not change any of the parameters in cultures of Caco-2 cells. HES is able to disturb the integrity of the endothelial but not the epithelial barrier in vitro. HES effects are unrelated to cell damage and apoptosis but may involve reduced cell-cell or cell-matrix adhesion.

Hydroxyethyl Starch 130/0.4 Binds to Neutrophils Impairing Their Chemotaxis through a Mac-1 Dependent Interaction

Several studies showed that hydroxyethyl starch (HES), a synthetic colloid used in volume replacement therapies, interferes with leukocyte-endothelium interactions. Although still unclear, the mechanism seems to involve the inhibition of neutrophils' integrin. With the aim to provide direct evidence of the binding of HES to neutrophils and to investigate the influence of HES on neutrophil chemotaxis, we isolated and treated the cells with different concentrations of fluorescein-conjugated HES (HES-FITC), with or without different stimuli (N-Formylmethionine-leucyl-phenylalanine, fMLP, or IL-8). HES internalization was evaluated by trypan blue quenching and ammonium chloride treatment. Chemotaxis was evaluated by under-agarose assay after pretreatment of the cells with HES or a balanced saline solution. The integrin interacting with HES was identified by using specific blocking antibodies. Our results showed that HES-FITC binds to the plasma membrane of neutrophils without being internalized. Additionally, the cell-associated fluorescence increased after stimulation of neutrophils with fMLP (p < 0.01) but not IL-8. HES treatment impaired the chemotaxis only towards fMLP, event mainly ascribed to the inhibition of CD-11b (Mac-1 integrin) activity. Therefore, the observed effect mediated by HES should be taken into account during volume replacement therapies. Thus, HES treatment could be advantageous in clinical conditions where a low activation/recruitment of neutrophils may be beneficial, but may be harmful when unimpaired immune functions are mandatory.

Audit of preoperative fluid resuscitation in perforation peritonitis patients using Physiological and Operative Severity Score for enUmeration of Mortality and Morbidity

Context:

Debate continues regarding fluid (crystalloid vs. colloid) of choice for resuscitation. Physiological and Operative Severity Score for enUmeration of Mortality and Morbidity (POSSUM) may be used to compare the benefits of preoperative fluid resuscitation with crystalloids and colloids in peritonitis patients.

Aims:

The aim of this study is to compare crystalloid and colloid for preoperative resuscitation using morbidity, mortality, length of hospital stay (LOS), and time taken to resuscitate as the outcome parameters.

Settings and Design:

This was a prospective randomized clinical trial.

Subjects and Methods:

One hundred and seven peritonitis patients were prospectively randomized to fluid resuscitation by crystalloid (Group A) and colloid (Group B) solutions. Physiological score component of POSSUM was recorded before and after fluid resuscitation; operative score component was recorded at discharge/death. These scores were then used to calculate the predicted morbidity and mortality before and after the fluid resuscitation.

Statistical Analysis Used:

Effect on morbidity and mortality were compared by repeated measure analysis of variance, and its significance was tested by Tukey's test. LOS and time taken to resuscitate were compared using unpaired t-test. Significance was taken at 5%.

Results:

Fluid resuscitation improved mean predicted morbidity by 0.095 and 0.137 in Group A and Group B, respectively. Similarly, fluid resuscitation improved predicted mortality by 0.145 and 0.185 in Group A and Group B, respectively. These changes were statistically significant. Improvement in morbidity and mortality appeared greater in Group B. No difference was found in the two groups for LOS and time to resuscitate.

Conclusions:

Preoperative fluid resuscitation using either crystalloid or colloidal solutions decreases morbidity as well as mortality in peritonitis patients.

Hydroxyethyl starch: a review of pharmacokinetics, pharmacodynamics, current products, and potential clinical risks, benefits, and use

OBJECTIVE

To review and summarize the pharmacokinetics and pharmacodynamics of hydroxyethyl starch (HES), as well as reported risks and benefits of HES infusion, and to provide administration and monitoring recommendations for HES use in dogs and cats.

DATA SOURCES

Veterinary and human peer-reviewed medical literature, including scientific reviews, clinical and laboratory research articles, and authors' clinical experience.

SUMMARY

HES solutions are the most frequently used synthetic colloid plasma volume expanders in human and veterinary medicine. The majority of research in human medicine has focused on the adverse effects of HES infusion, with emphasis on acute kidney injury and coagulation derangements. The studies often differ in or fail to report factors, such as the type, amount, interval, and concentration of HES administered; the patient population studied; or concurrent fluids administered. Currently, there is no definitive clinical evidence that the reported adverse effects of HES use in human medicine occur in veterinary species. There is little information available on HES administration techniques or simultaneous administration of additional fluids in human and veterinary medicine. The rationale for HES use in small animals has been largely extrapolated from human medical studies and guidelines. A controlled approach to intravenous fluid resuscitation using crystalloid and HES volumes titrated to reach desired resuscitation end point parameters is outlined for small animal practitioners.

CONCLUSION

The extrapolation of data from human studies directly to small animals should be done with the knowledge that there may be species variations and different pharmacokinetics with different HES solutions. Veterinary reports indicate that bolus and continuous rate infusions of 6% hetastarch solutions at moderate doses are well tolerated in feline and canine subjects. Further research in domesticated species is necessary to better define and expand the knowledge regarding use of HES solutions in small animal medicine.

Effect of 6% hydroxyethyl starch 130/0.4 in 0.9% sodium chloride (Voluven®) on complications after subarachnoid hemorrhage: a retrospective analysis

Background

6% Hydroxyethyl Starch 130/0.4 in 0.9% Sodium Chloride (Voluven®; 6% HES 130/0.4) is a colloid often used for fluid resuscitation in patients with subarachnoid hemorrhage (SAH), despite a lack of safety data for this use. The purpose of our study was to evaluate the effect of 6% HES 130/0.4 on major complications associated with SAH.

Methods

Medical records of all patients presenting between May 2010 and September 2012 with aneurysmal SAH were analyzed. Patients were divided in two groups based on the administration of 6% HES 130/0.4; HES group (n=57) and Non-HES group (n=72). The primary outcome included a composite of three major complications associated with SAH: Delayed Cerebral Ischemia (DCI), Hydrocephalus (HCP) requiring cerebrospinal fluid (CSF) shunting, and Rebleeding.

Results

The study groups were similar with respect to most characteristics except the incidences of hypertension, ischemic heart disease, Fisher grade and lowest hemoglobin during stay. The odds of developing the primary composite outcome was higher in the HES group [OR= 3.1(1.30-7.36), p=0.01]. The patients in the HES group had a significantly longer median duration of hospital (19 vs 14 days) and Neurointensive Care Unit stay (14 vs 10 days) compared to the Non HES group.

Conclusion

We observed increased complications after SAH with 6% HES 130/0.4 (Voluven®) administration. An adequately powered prospective randomized controlled trial into the safety of 6% HES 130/0.4 in this patient population is warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/2193-1801-2-314) contains supplementary material, which is available to authorized users.

Effect of molecular weight and substitution on tissue uptake of hydroxyethyl starch: a meta-analysis of clinical studies

BACKGROUND

Intravenously infused hydroxyethyl starch (HES) can be found in urine, plasma and tissues. HES remaining in plasma and tissues is thought to increase the risk of clinical complications. HES solutions of lower molecular weight and substitution have been developed to increase urinary excretion and reduce plasma persistence. However, their effect on tissue uptake of HES has not been investigated in human subjects.

OBJECTIVE

Our objective was to test the hypothesis that lower molecular weight and substitution decrease tissue uptake of HES.

DATA SOURCES

Computer searches were performed of MEDLINE; EMBASE; the Cochrane Library; meeting abstract databases in surgery, anaesthesiology and intensive care; ClinicalTrials.gov; and Google. Supplementary sources were reference lists and electronic tables of journal contents. No time period or language restrictions were imposed.

STUDY SELECTION

Clinical studies were eligible for inclusion in the meta-analysis, if data were reported both for cumulative urinary excretion of HES over 24 hours after infusion and for plasma HES concentration at 24 hours.

DATA EXTRACTION

Data were extracted on 24-hour urinary excretion of HES, 24-hour HES plasma concentration, plasma volume, HES molecular weight and substitution, study design, type and demographics of subjects, indication for fluid infusion, and HES infusion regimen. Tissue uptake of HES was computed as the difference between the infused dose and the sum of urinary excretion and residual plasma HES at 24 hours.

DATA SYNTHESIS

Twenty-five clinical studies totalling 287 subjects were included. Tissue uptake of low-molecular-weight HES (≤200 kD) was 42.3% (95% confidence interval [CI] 39.6, 45.0) compared with 24.6% (CI 17.8, 31.4) for high-molecular-weight HES (p < 0.001). Similarly, tissue uptake of lower-substitution HES (≤0.5) was 42.4% (CI 39.5, 45.3) versus 26.6% (CI 19.6, 33.6) for higher-substitution HES (p < 0.001). Among the three most often investigated single HES solutions, tissue uptake of 130/0.4 (42.6%; CI 35.0, 50.2) and HES 200/0.5 (43.3%; CI 39.4, 47.2) closely coincided, whereas uptake of HES 450/0.7 (22.2%; CI 14.8, 29.6) was lower (p = 0.001 and p < 0.001, respectively).

CONCLUSIONS

This meta-analysis did not support the hypothesis that lower molecular weight and substitution decrease tissue uptake of HES. Further clinical studies of HES tissue uptake are needed.

Hydroxyethylstarch in cryopreservation - mechanisms, benefits and problems

As the progress of regenerative medicine places ever greater attention on cryopreservation of (stem) cells, tried and tested cryopreservation solutions deserve a second look. This article discusses the use of hydroxyethyl starch (HES) as a cryoprotectant. Charting carefully the recorded uses of HES as a cryoprotectant, in parallel to its further clinical use, indicates that some HES subtypes are a useful supplement to dimethysulfoxide (DMSO) in cryopreservation. However, we suggest that the most common admixture ratio of HES and DMSO in cryoprotectant solutions has been established by historical happenstance and requires further investigation and optimization.

[Volume replacement in intensive care medicine]

Volume substitution represents an essential component of intensive care medicine. The amount of fluid administered, the composition and the timing of volume replacement seem to affect the morbidity and mortality of critically ill patients. Although restrictive volume strategies bear the risk of tissue hypoperfusion and tissue hypoxia in hemodynamically unstable patients liberal strategies favour the development of avoidable hypervolemia with edema and resultant organ dysfunction. However, neither strategy has shown a consistent benefit. In order to account for the heavily varying oxygen demand of critically ill patients, a goal-directed, demand-adapted volume strategy is proposed. Using this strategy, volume replacement should be aligned to the need to restore tissue perfusion and the evidence of volume responsiveness. As the efficiency of volume resuscitation for correction of tissue hypoxia is time-dependent, preload optimization should be completed in the very first hours. Whether colloids or crystalloids are more suitable for this purpose is still controversially discussed. Nevertheless, a temporally limited use of colloids during the initial stage of tissue hypoperfusion appears to represent a strategy which uses the greater volume effect during hypovolemia while minimizing the risks for adverse reactions.

Postoperative ileus: pathogenesis and treatment

Surgical manipulation of the intestines activates intestinal macrophages that release cytokines and nitric oxide, which results in inhibition of intestinal motility. Subsequent infiltration of circulating leukocytes into the intestinal wall contributes to cytokine and nitric oxide release and exacerbates ileus. Other factors contributing to ileus are endotoxemia; edema of the intestine wall subsequent to excessive fluid therapy; hypocalcemia; and long abdominal incisions. Because treatment of ileus with prokinetic drugs has not proven to be very effective, efforts should be directed at reducing its severity. Strategies which reduce the severity of ileus include pretreatment with a nonsteroidal anti-inflammatory drug, minimizing the length of the abdominal incision, reducing intestinal manipulation, intraoperative lidocaine infusion, correction of hypocalcemia, limiting the volume of intravenous fluids to prevent intestinal edema, and administration of alpha(2) antagonists.

Randomized clinical trial comparing the effects on renal function of hydroxyethyl starch or gelatine during aortic aneurysm surgery

Background

The optimal colloid for renal protection during abdominal aortic aneurysm (AAA) surgery is not known. This study compared the effects of two hydroxyethyl starch (HES) solutions and gelatine on perioperative renal function.

Methods

Sixty-two patients undergoing AAA surgery were randomized to 6 per cent HES of molecular weight 200/0·62 kDa or 130/0·4 kDa, or 4 per cent gelatine for plasma expansion. Measurements were taken of serum urea and creatinine to mark glomerular filtration, urinary immunoglobulin G : creatinine ratio to mark glomerular membrane function and α1-microglobulin : creatinine ratio to mark tubular dysfunction before, and for 5 days after, surgery.

Results

Serum urea was lower in both HES groups than the gelatine group. Serum creatinine was lower with HES 130/0·4 compared with gelatine at days 1, 2 and 5 after surgery (P = 0·020, P = 0·045 and P = 0·045 respectively). Urinary α1-microglobulin : creatinine ratio was lower with HES 200/0·62 compared with gelatine at 4 and 8 h (P &lt; 0·050) and lower with HES 130/0·4 compared with gelatine at 4 to 24 h, and on days 4 and 5 (P &lt; 0·050). Urinary immunoglobulin G : creatinine was lower in both HES groups compared with gelatine. There was no difference between the two starch groups.

Conclusion

Compared with gelatine, volume expansion with both types of HES during AAA surgery improved renal function and reduced renal injury.

Effect of synthetic colloids on major histocompatibility complex class II expression

STUDY OBJECTIVE

Synthetic colloids are used for perioperative fluid management. We hypothesized that their use may be associated with changes in major histocompatibility complex (MHC) class II expression. This could affect patients' morbidity and mortality during clinical intervention.

SETTING

University research laboratory.

SUBJECTS

Whole blood samples from healthy volunteers.

INTERVENTIONS

Whole blood samples from healthy volunteers (n = 6) were incubated with different concentrations of hydroxyethyl starch (HES) from maize and potato (pHES), dextran, and polygelin (gelatine) for 24 hours with or without 100 U/mL human interferon gamma (IFN-gamma; stimulus for MHC class II expression). The expression of human leukocyte antigen (HLA): HLA-DR, HLA-DQ, and HLA-DP was detected simultaneously by a fluoresceinisothiocyanate (FITC)-labeled antibody and analyzed by flow cytometry on lymphocytes and monocytes.

MEASUREMENTS AND MAIN RESULTS

Hydroxyethyl starch, pHES, and dextran induced a significant increase in HLA expression. The induction of MHC class II was independent of the structure (50 mg/mL: control, 8.7+/-1.4%; HES, 28 +/- 9.7%; pHES, 29.8 +/- 11.7%; and dextran, 50.2 +/- 8.1%). In contrast, polygelin increased HLA expression only at the highest concentration of gelatine (5 mg/mL, 7.8 +/- 1%; 50 mg/mL, 7.6 +/- 0.8%; 100 mg/mL, 7.3 +/- 1%; 200 mg/mL,16.2 +/- 2.3%). The addition of IFN-gamma decreased HLA expression in presence of highest concentration of HES and dextran.

CONCLUSION

In an ex vivo laboratory setting, we demonstrate that high concentrations of plasma expanders are associated with increased HLA expression on lymphocytes and monocytes. However, further in vivo studies are necessary to demonstrate the clinical significance of this observation.

Hydroxyethyl starch inhibits neutrophil adhesion and transendothelial migration

A resuscitation strategy that significantly alters the state of neutrophil (PMN) activation may impact organ function and survivability after shock. Various resuscitative fluids have been shown to elicit a severe immune activation and an upregulation of cellular injury markers, whereas other fluids have been shown to be protective. Recent studies have demonstrated that hydroxyethyl starch (HES), an artificial colloid, may exert significant anti-inflammatory effects, whereas conflicting studies with the same substance have shown an increase in PMN activation. Successful manipulation of the early immune events associated with hemorrhage and resuscitation will require a better understanding of the possible pro- or anti-inflammatory effects of resuscitation fluids. Our study investigated the effect of HES directly on PMN and cultured vascular endothelial cells in vitro. The effect of HES on PMN surface expression of CD11b and L-selectin was measured by flow cytometry. PMN activation response to HES was measured using a shape-change assay in response to formyl-methionyl-leucyl-phenylalanine (f-MLP). The effect of HES on endothelial cell surface expression of E-selectin, P-selectin, vascular cell adhesion molecule-1(VCAM-1), and intracellular adhesion molecule-1 (ICAM-1) was evaluated by enzyme-linked immunoabsorbant assay. PMN rolling, adhesion, and migration events were measured using direct microscopy under conditions simulating microvascular flow. PMN surface expression of CD11b and L-selectin in whole blood samples and isolated PMNs were unaffected by exposure to HES. HES had no effect on the normal f-MLP dose-dependent increase in PMN activation. In the absence of IL-1 stimulation, there was a small but statistically significant (P < 0.05) increase in ICAM-1 after exposure to HES. After stimulation with IL-1 (10 U/mL), HES had no effect on the expression of P-selectin, E-selectin, ICAM-1, or VCAM-1. Under simulated microvascular flow conditions in vitro, HES significantly diminished the PMN tethering rate (P < 0.05) and the transendothelial migration rate (P < 0.05) in a dose-dependent manner. HES significantly alters the function of the PMN at the interface of the PMN responding to activated endothelium. The effect occurs, surprisingly, without a coincident effect on the state of PMN activation or a significant change in the surface expression of the adhesion molecules responsible for PMN-endothelial interaction.

Pruritus precipitated by hydroxyethyl starch: a review

Hydroxyethyl starch (HES) is widely used for fluid management in broad populations of patients, particularly in the surgery and intensive care settings. Pruritus, often manifested as pruritic crises, is increasingly being recognized as a common major adverse effect of HES administration. This iatrogenic form of pruritus is frequently severe and protracted with a serious negative impact on patient quality of life, including sleep disturbance, disruption of daily routine and mental distress. Such pruritus is generally refractory to available therapies and can persist for up to 12-24 months. All currently clinically available HES solutions entail the risk of pruritus, including those of diverse molecular weights and substitutions. Although dose dependent, HES-induced pruritus nevertheless can often be provoked by relatively low routine doses. The pathophysiological basis for pruritus is the widespread tissue deposition of HES, prominently in macrophages. HES tissue deposits are long lasting and sometimes massive. Usually several weeks elapse between HES exposure and the onset of pruritus. Consequently, it is important to inquire about prior HES exposure in the diagnostic evaluation of pruritus sine materia. Awareness about the scope of the pruritus problem needs to increase among physicians administering HES. Well-designed clinical outcome studies are needed to assess more fully the incidence, dose dependency and mechanisms of pruritus with particular HES solutions.

The effects of hydroxyethyl starch on lung capillary permeability in endotoxic rats and possible mechanisms

In this study we examined the effects of hydroxyethyl starch (HES 200/0.5) on lung capillary permeability in endotoxic rats and explored the possible mechanisms. Male Wistar rats were randomly divided into seven groups treated with saline, lipopolysaccharide (LPS; 6 mg/kg), LPS plus HES (3.75, 7.5, 15, or 30 mL/kg), or HES (30 mL/kg) alone for 4 or 2 h. Lung capillary permeability, lung neutrophil accumulation, expression of CD11b on the blood neutrophil cell surface, lung cytokine-induced neutrophil chemoattractant protein level, and nuclear factor kappa B (NF-kappaB) activation in blood neutrophils and lungs were measured. HES at doses of 3.75 and 7.5 mL/kg significantly reduced LPS-induced increases of lung capillary permeability. HES was found to inhibit lung neutrophil accumulation, cytokine-induced neutrophil chemoattractant protein, and NF-kappaB activation in parallel and to inhibit CD11b expression in a dose-dependent manner. These findings demonstrate that HES has beneficial effects on capillary leak in acute lung injury and that the mechanisms underlying this action involve an antiinflammatory effect of HES, including inhibition of NF-kappaB activation.

IMPLICATIONS

A randomized, controlled laboratory experiment indicated that hydroxyethyl starch (HES) could reduce increased lung capillary permeability in endotoxemia. This effect may be due to an antiinflammatory effect of HES.