Production of human albumin solution: a continually developing colloid

Use of a Novel Buffered Hypertonic Saline Solution for Fluid Replacement and Resuscitation During Spinal Surgery in Adolescents

Background

During major orthopedic procedures, such as posterior spinal fusion (PSF), isotonic fluids, colloids, starches, or gelatins are commonly used to replace the preoperative fluid deficit and provide ongoing fluid resuscitation. Given recent concerns regarding the potential adverse physiologic effects of albumin solutions, we have modified our intraoperative practice to include the use of a novel 2% buffered hypertonic saline solution during major orthopedic procedures. We present our preliminary clinical experience with this novel fluid for intraoperative resuscitation and its impact on limiting the use of 5% albumin.

Methods

A retrospective review was performed to identify patients who received 2% buffered hypertonic saline during PSF. The intraoperative course of these patients was compared to case-matched control patients who received standard care with isotonic fluids plus 5% albumin as an adjunct for intravascular resuscitation.

Results

The study cohort included 23 patients who received 2% buffered hypertonic saline and 25 in the case-matched control group. There was no difference in the volume of intraoperative isotonic crystalloid fluids, estimated blood loss, and urine output between the two groups. In the control cohort, 19 of 25 patients (76%) received 5% albumin compared to only six of 23 patients (26%, P = 0.0005) in the 2% buffered hypertonic saline group. The final pH was higher in the patients that received 2% buffered hypertonic saline than in the control group (7.40 ± 0.03 versus 7.36 ± 0.06, P = 0.0131). Additionally, the starting and final serum sodium values were higher in the patients that received 2% buffered hypertonic saline, although no difference was noted in the mean change from the starting value (average increase of 2 mEq/L in both groups).

Conclusion

Use of a novel 2% buffered hypertonic saline solution for intraoperative resuscitation during major orthopedic procedures decreases the need for 5% albumin while avoiding the development of hyperchloremic metabolic acidosis which may occur with standard sodium chloride solutions.

Perspectives on Multiscale Colloid-Based Materials for Biomedical Applications

Colloid-based materials with tunable biophysical and chemical properties have demonstrated significant potential in a wide range of biomedical applications. The ability to manipulate these properties across various size scales, encompassing nano-, micro-, and macrodomains, is essential to enhancing current biomedical technologies and facilitating the development of novel applications. Focusing on material design, we explore various synthetic colloid-based materials at the nano- and microscales and investigate their correlation with biological systems. Furthermore, we examine the utilization of the self-assembly of colloids to construct monolithic and macroscopic materials suitable for biointerfaces. By probing the potential of spatial imaging and localized drug delivery, enhanced functionality, and colloidal manipulation, we highlight emerging opportunities that could significantly advance the field of colloid-based materials in biomedical applications.

Mass Spectrometry, Structural Analysis, and Anti-Inflammatory Properties of Photo-Cross-Linked Human Albumin Hydrogels

Albumin-based hydrogels offer unique benefits such as biodegradability and high binding affinity to various biomolecules, which make them suitable candidates for biomedical applications. Here, we report a non-immunogenic photocurable human serum-based (HSA) hydrogel synthesized by methacryloylation of human serum albumin by methacrylic anhydride (MAA). We used matrix-assisted laser desorption ionization-time-of-flight mass spectrometry, liquid chromatography-tandem mass spectrometry, as well as size exclusion chromatography to evaluate the extent of modification, hydrolytic and enzymatic degradation of methacrylated albumin macromer and its cross-linked hydrogels. The impacts of methacryloylation and cross-linking on alteration of inflammatory response and toxicity were evaluated in vitro using brain-derived HMC3 macrophages and Ex-Ovo chick chorioallantoic membrane assay. Results revealed that the lysines in HSA were the primary targets reacting with MAA, though modification of cysteine, threonine, serine, and tyrosine, with MAA was also confirmed. Both methacrylated HSA and its derived hydrogels were nontoxic and did not induce inflammatory pathways, while significantly reducing macrophage adhesion to the hydrogels; one of the key steps in the process of foreign body reaction to biomaterials. Cytokine and growth factor analysis showed that albumin-based hydrogels demonstrated anti-inflammatory response modulating cellular events in HMC3 macrophages. Ex-Ovo results also confirmed the biocompatibility of HSA macromer and hydrogels along with slight angiogenesis-modulating effects. Photocurable albumin hydrogels may be used as a non-immunogenic platform for various biomedical applications including passivation coatings.

Therapeutic solutions of human albumin - The possible effect of process-induced molecular alterations on clinical efficacy and safety

Human albumin solutions were developed as therapeutic during the Second World War to address blood loss due to battlefield injury. This indication was based on the recognition that albumin provided most of the oncotic capacity of human plasma. For the succeeding sixty years, this formed the basis for the use of albumin in traumatology and emergency medicine. In more recent times, the pharmacological properties arising from albumin's complex structure have become a focus of attention by clinical researchers. In particular, albumin, through anti-inflammatory and anti-oxidant properties, has been proposed as an agent for the treatment of sepsis, cirrhosis and other inflammatory states. Some evidence for these indications has accrued from a number of small clinical trials and observational studies. These studies have not been confirmed in other large trials. Together with other investigators, we have shown that the process of plasma fractionation results in alterations in the structure of albumin, including those parts of the molecule involved in anti-oxidant and anti-inflammatory effects. Albumin products from diverse manufacturers show heterogeneity in their ability to address these effects. In this article, we review the historical development of albumin solutions, pointing out the variations in fractionation chemistries which different manufacturers have adopted. We suggest ways by which the manufacturing processes have contributed to variations in the physico-chemical properties of molecule. We review the outcomes of clinical studies assessing the role of albumin in ameliorating conditions such as sepsis and cirrhosis, and we speculate as to the extent which heterogeneity in the products may have contributed to variable clinical outcomes. Finally, we argue for a change in the perception of the plasma product industry and its regulatory overseers. Historically, albumin has been viewed as a generic commodity, with different preparations being interchangeable in their clinical application. We suggest that this implied biosimilarity is not necessarily applicable for different albumin solutions. The use of albumin, in indications other than its historical role as a plasma expander, can only be validated by clinical investigation of each separate albumin product.

Chemically Modified Biopolymers for the Formation of Biomedical Hydrogels

Biopolymers are natural polymers sourced from plants and animals, which include a variety of polysaccharides and polypeptides. The inclusion of biopolymers into biomedical hydrogels is of great interest because of their inherent biochemical and biophysical properties, such as cellular adhesion, degradation, and viscoelasticity. The objective of this Review is to provide a detailed overview of the design and development of biopolymer hydrogels for biomedical applications, with an emphasis on biopolymer chemical modifications and cross-linking methods. First, the fundamentals of biopolymers and chemical conjugation methods to introduce cross-linking groups are described. Cross-linking methods to form biopolymer networks are then discussed in detail, including (i) covalent cross-linking (e.g., free radical chain polymerization, click cross-linking, cross-linking due to oxidation of phenolic groups), (ii) dynamic covalent cross-linking (e.g., Schiff base formation, disulfide formation, reversible Diels-Alder reactions), and (iii) physical cross-linking (e.g., guest-host interactions, hydrogen bonding, metal-ligand coordination, grafted biopolymers). Finally, recent advances in the use of chemically modified biopolymer hydrogels for the biofabrication of tissue scaffolds, therapeutic delivery, tissue adhesives and sealants, as well as the formation of interpenetrating network biopolymer hydrogels, are highlighted.

Safety verification for polysorbate 20, pharmaceutical excipient for intramuscular administration, in Sprague-Dawley rats and New Zealand White rabbits

Human serum albumin (HSA) has been widely used as a pharmaceutical excipient in Botulinum toxin serotype A (BoNT/A) products that are indicated for use in therapeutics and cosmetics. However, HSA as a human-derived material has some concerns, such as the potential risk of transmission of infectious agents, an insufficient supply, and difficulty in maintaining a certain quality. For those reasons, newly developed BoNT/A products (CORETOX^®, Medytox, Inc., Republic of Korea) contained polysorbate 20, a non-human-derived excipient, to replace the HSA. However, most safety studies of polysorbate 20 have been conducted with non-invasive routes of administration, and thus there are a few studies on the safety of polysorbate 20 when administered intramuscularly. To secure the in vivo safety profile of polysorbate 20, a four-week repeated intramuscular dose toxicity study (0.02, 0.1, and 0.4 mg/kg, one injection every two weeks for a total of three injections) was conducted in 66 Sprague-Dawley (SD) rats. An intradermal irritation study was further conducted with 18 New Zealand White (NZW) rabbits. The toxicological evaluation of HSA (0.06 and 0.12 mg/kg) was also carried out as a comparative substance. Systemic and local toxicities were not observed in any of the SD rats or NZW rabbits based on clinical signs, body weight, hematology, clinical biochemistry, macroscopic findings on necropsy, histopathology of the injection site, and allergic reactions. The current study suggested that intramuscular administration of polysorbate 20 was considered to be safe at a level similar to that of HSA, which has an in vivo safety profile accumulated over the years. This provided the basis for the in vivo safety profile of polysorbate 20 administered intramuscularly and the scientific reliability of the use of polysorbate 20 as an alternative to HSA, which is used as an excipient for various pharmaceuticals in terms of its safety.

A randomized dose-escalation study on the safety, tolerability, immunogenicity, pharmacokinetics and pharmacodynamics of a novel recombinant human albumin in healthy subjects

OBJECTIVE

Recombinant human albumin (rHA) is an alternative to human serum albumin (HSA) for treating ascites in cirrhosis patients. This study was to evaluate the safety, tolerability, immunogenicity, and pharmacokinetics/pharmacodynamics (PK/PD) of rHA in healthy subjects to guide the design for further clinical trials.

METHODS

Healthy subjects aged 18-55 years were enrolled in this double-blinded, first-in-human, placebo-controlled single ascending dose (SAD) (1.25, 5, 10, 20, or 30g) and positive-controlled multiple-dose study (3-day treatment of 10g/day for three cycles every three weeks). The safety was assessed by adverse events (AEs). Antibodies (IgE and IgD) and cytokines were analyzed for immunogenicity. Serum albumin levels and changes in plasma colloid osmotic pressure (PCOP) and hematocrit (HCT) were measured for PK/PD analysis.

RESULTS

rHA was well tolerated as all AEs were assessed as mild or moderate. No severe allergy or difference in the incidence of AEs was observed among the different cohorts in the SAD study or in the different cycles in the multiple-dose study. The incidence of AEs was similar for the rHA and HSA cohort. Antibodies or cytokines showed no changes after drug administration. As expected, serum albumin levels and PCOP increases, and HCT ratio decreases were dose-related with significant differences (p < 0.01). No differences were observed between rHA and HSA.

CONCLUSION

rHA is safe and well-tolerated in healthy Chinese subjects. rHA and HSA exhibited similar safety, tolerability, and PK/PD profiles. The results support further evaluation of rHA treatment in cirrhotic patients with ascites. The clinical trial registration numbers are CTR20191221 (http://www.chinadrugtrials.org.cn/clinicaltrials.searchlistdetail.dhtml).

Intravenous Albumin for Mitigating Hypotension and Augmenting Ultrafiltration during Kidney Replacement Therapy

Among its many functions, owing to its oversized effect on colloid oncotic pressure, intravascular albumin helps preserve the effective circulatory volume. Hypoalbuminemia is common in hospitalized patients and is found especially frequently in patients who require KRT either for AKI or as maintenance hemodialysis. In such patients, hypoalbuminemia is strongly associated with morbidity, intradialytic hypotension, and mortality. Intravenous albumin may be administered in an effort to prevent or treat hypotension or to augment fluid removal, but this practice is controversial. Theoretically, intravenous albumin administration might prevent or treat hypotension by promoting plasma refilling in response to ultrafiltration. However, clinical trials have demonstrated that albumin administration is not nearly as effective a volume expander as might be assumed according to its oncotic properties. Although intravenous albumin is generally considered to be safe, it is also very expensive. In addition, there are potential risks to using it to prevent or treat intradialytic hypotension. Some recent studies have suggested that hyperoncotic albumin solutions may precipitate or worsen AKI in patients with sepsis or shock; however, the overall evidence supporting this effect is weak. In this review, we explore the theoretical benefits and risks of using intravenous albumin to mitigate intradialytic hypotension and/or enhance ultrafiltration and summarize the current evidence relating to this practice. This includes studies relevant to its use in patients on maintenance hemodialysis and critically ill patients with AKI who require KRT in the intensive care unit. Despite evidence of its frequent use and high costs, at present, there are minimal data that support the routine use of intravenous albumin during KRT. As such, adequately powered trials to evaluate the efficacy of intravenous albumin in this setting are clearly needed.

Absence of the CXCR4 antagonist EPI-X4 from pharmaceutical human serum albumin preparations

BACKGROUND

Endogenous Peptide Inhibitor of CXCR4 (EPI-X4) is a natural antagonist of the CXC chemokine receptor 4 (CXCR4). EPI-X4 is a 16-mer peptide that is released from human serum albumin (HSA) by acidic aspartic proteases such as Cathepsin D and E. Since human serum albumin (HSA) is an important medicinal substance we asked whether different pharmaceutical HSA products contain EPI-X4 which could have been generated during manufacturing and whether HSA can serve as a substrate for cathepsins despite of the presence of stabilizers like caprylate.

METHODS

Eight pharmaceutical HSA preparations representing all currently used fractionation technologies were analyzed. The previously described specific EPI-X4 ELISA was used for quantification; in vitro EPI-X4 generation by acidification in the presence or absence of cathepsins was followed by quantification with ELISA.

RESULTS

None of the pharmaceutical HSA preparations tested contained EPI-X4. Acidification of HSA did not generate EPI-X4. Addition of cathepsins D and E to acidified HSA yielded high concentrations of EPI-X4 in all HSA preparations, indistinguishable between individual products.

CONCLUSION

Medicinal HSA preparations per se do not contain EPI-X4, but will replenish its precursor which can be cleaved to EPI-X4 in vivo, environmental conditions permitting.

Human albumin solutions in intensive care: A review

Albumin plays a key role in the critically ill patient acting as a prognostic marker and as a therapy in the form of human albumin solutions. However, the use of human albumin solution has varied over time with notable differences between health systems. Whilst its use is widely accepted for some clinical indications, its role has not always been clear in the critically ill and has been found to be harmful in some cohorts. Numerous studies have showed conflicting results and critical care clinicians have not always been guided by robust evidence. Nonetheless, at present the use of human albumin solution appears to be increasing again in the United Kingdom. Below, we discuss the latest evidence base for its use in critically ill patients.

Albumin as a drug: its biological effects beyond volume expansion

Albumin is the most abundant and perhaps most important protein in human blood. Research has identified many of albumin's possible roles in modulating acid-base balance, modifying inflammation, maintaining vascular endothelial integrity, and binding endogenous and exogenous compounds. Albumin plays a key role in the homeostasis of vascular endothelium, offering protection from inflammation and damage to the glycocalyx. Albumin binds a diverse range of compounds. It transports, delivers and clears drugs, plus it helps with uptake, storage and disposal of potentially harmful biological products. The biological effects of albumin in critical illness are incompletely understood, but may enhance its clinical role beyond use as an intravenous fluid. In this article, we summarise the evidence surrounding albumin's biological and physiological effects beyond its use for plasma volume expansion, and explore potential mechanistic effects of albumin as a disease modifier in patients with critical illness.

Serum Albumin, Lipid and Drug Binding

Albumin is widely conserved from vertebrates to invertebrates, and nature of mammalian albumins permit them to bind various endogenous ligands and drugs in the blood. It is known that at least two major ligand binding sites are present on the albumin molecule, which are referred to as Site I and Site II. These binding sites are thought to be almost completely conserved among mammals, even though the degree of binding to these sites are different depending on the physical and chemical properties of drugs and differences in the microenvironment in the binding pockets. In addition, the binding sites for medium and long-chain fatty acids are also well conserved among mammals, and it is considered that there are at least seven binding sites, including Site I and Site II. These bindings properties of albumin in the blood are also widely known to be important for transporting drugs and fatty acids to various tissues. It can therefore be concluded that albumin is one of the most important serum proteins for various ligands, and information on human albumin can be very useful in predicting the ligand binding properties of the albumin of other vertebrates.

Effects of dietary supplementation of l-methionine vs. dl-methionine on performance, plasma concentrations of free amino acids and other metabolites, and myogenesis gene expression in young growing pigs

Methionine (Met), the second or third limiting amino acid (AA) in typical swine diets, plays important roles in promoting swine health and growth, especially, muscle growth. Whereas dl-Met products have been used in swine industry for many years, l-Met products have been developed recently. This research was conducted to study the effects of supplemental l-Met or dl-Met on nutrient metabolism, muscle gene expression, and growth performance of pigs. Twenty crossbred young barrows (initial body weight [BW] 21.2 ± 2.7 kg) were randomly assigned to 20 individual pens and two dietary treatments according to a completely randomized design with pigs serving as the experiment unit (n = 10). Two corn and soybean meal-based diets (diets 1 and 2) were formulated to meet or exceed the recommended requirements for energy, AA, and other nutrients (NRC. 2012. Nutrient requirements of swine, 11th ed. Washington, DC: The National Academies Press; AMINODat 5.0). Crystalline l-Met and dl-Met were supplemented to diets 1 and 2 (both at 0.13%, as-fed basis), respectively. After 4 wk of an ad libitum feeding trial, BW and feed intake were measured to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). Blood samples were collected from the jugular vein for analyses of plasma AA and metabolite concentrations. The longissimus dorsi muscle samples were collected for analysis of myogenesis gene expression. Data were analyzed using Student's t-test. There were no differences (P = 0.56 to 0.94) in ADG, ADFI, or G:F between pigs fed the two experimental diets and no differences between diets were observed in plasma free AA concentrations. No differences were observed between pigs fed the two diets in expression of mRNA for eight myogenesis-related genes, which were myogenic differentiation 1, myogenin, myogenic factors 5, muscle regulatory factor 4 (a.k.a. myogenic factors 6), and myocyte enhancer factors 2A, 2B, 2C, and 2D. In conclusion, results of this experiment indicate that the bioefficacy of l-Met is not different from that of dl-Met, which is likely because of an efficient conversion of d-Met to l-Met by pigs.

Effects of dietary lysine levels on the concentrations of selected nutrient metabolites in blood plasma of late-stage finishing pigs

Lysine is the first-limiting amino acid (AA) in typical swine diets and plays very important roles in promoting growth performance of pigs. This research was conducted to study the effects of dietary lysine on blood plasma concentrations of protein, carbohydrate, and lipid metabolites of pigs. Eighteen crossbred finishing pigs (nine barrows and nine gilts; initial BW 92.3 ± 6.9 kg) were individually penned in an environment controlled barn. Pigs were assigned to three dietary treatments according to a randomized complete block design with gender as block and pig as experimental unit (6 pigs/treatment). Three corn and soybean meal-based diets were formulated to contain total lysine at 0.43%, 0.71%, and 0.98% (as-fed basis) for Diets I (lysine deficient), II (lysine adequate), and III (lysine excess) respectively. After 4 weeks on trial, jugular vein blood was collected and plasma was separated. The plasma concentrations of total protein, albumin, urea nitrogen (UN), triglyceride, total cholesterol, and glucose were determined using an ACE Clinical Chemistry System (Alfa Wassermann, Inc., West Caldwell, NJ, USA). Data were analysed using the GLM Procedure with PDIFF (adjust = T) option of SAS. No differences (p > 0.10) were found between barrows and gilts for any of the metabolites measured. While there were no differences (p > 0.10) between pigs fed Diets II and III in plasma concentrations of UN, albumin, and total cholesterol, the concentration of albumin in these pigs was higher (p < .05) than that of pigs fed Diet I, and the concentrations of UN and total cholesterol in these pigs were lower (p < .05) than that of pigs fed Diet I. There were no differences (p > 0.10) among the three dietary treatments in plasma concentrations of total protein, triglycerides, and glucose. These findings indicated that the plasma metabolite profile can be affected by changing dietary lysine content only. Thorough understanding how the plasma metabolite profile is alternated by dietary lysine will facilitate nutrient management for more sustainable swine production.

Fluid Composition and Clinical Effects

The range of intravenous fluids available for therapeutic use and the differing indications are diverse. A solid understanding of the composition of different types of fluids is essential to understanding the physiologic effects following administration and the appropriate clinical application. In this review, the authors describe the different fluids commonly available and discuss the potential benefits and harms depending on the clinical circumstances.

Rediscovery and Revival of Analytical Refractometry for Protein Determination: Recombining Simplicity With Accuracy in the Digital Era

Among "vintage" methods of protein determination, quantitative analytical refractometry has received far less attention than well-established pharmacopoeial techniques based on protein nitrogen content, such as Dumas combustion (1831) and Kjeldahl digestion (1883). Protein determination by quantitative refractometry dates back to 1903 and has been extensively investigated and characterized in the following 30 years, but has since vanished into a few niche applications that may not require the degree of accuracy and precision essential for pharmaceutical analysis. However, because high-resolution and precision digital refractometers have replaced manual instruments, reducing time and resource consumption, the method appears particularly attractive from an economic, ergonomic, and environmental viewpoint. The sample solution can be measured without dilution or other preparation procedures than the separation of the protein-free matrix by ultrafiltration, which might even be omitted for a constant matrix and excipient composition.

Randomised trials of human albumin for adults with sepsis: systematic review and meta-analysis with trial sequential analysis of all-cause mortality

OBJECTIVE

To assess the efficacy and safety of pooled human albumin solutions as part of fluid volume expansion and resuscitation (with or without improvement of baseline hypoalbuminaemia) in critically unwell adults with sepsis of any severity.

DESIGN

Systematic review and meta-analysis of randomised clinical trials, with trial sequential analysis, subgroup, and meta-regression analyses.

DATA SOURCES

PubMed, PubMed Central, Web of Science (includes Medline, Conference Proceedings Citation Index, Data Citation Index, Chinese Science Citation Database, CAB abstracts, Derwent Innovations Index), OvidSP (includes Embase, Ovid Medline, HMIC, PsycINFO, Maternity and Infant Care, Transport Database), Cochrane Library, clinicaltrials.gov, controlled-trials.com, online material, relevant conference proceedings, hand searching of reference lists, and contact with authors as necessary.

ELIGIBILITY CRITERIA

Prospective randomised clinical trials of adults with sepsis of any severity (with or without baseline hypoalbuminaemia) in critical or intensive care who received pooled human albumin solutions as part of fluid volume expansion and resuscitation (with or without improvement of hypoalbuminaemia) compared with those who received control fluids (crystalloid or colloid), were included if all-cause mortality outcome data were available. No restriction of language, date, publication status, or primary study endpoint was applied.

DATA EXTRACTION

Two reviewers independently assessed articles for inclusion, extracted data to assess risk of bias, trial methods, patients, interventions, comparisons, and outcome. The relative risk of all-cause mortality was calculated using a random effects model accounting for clinical heterogeneity.

PRIMARY OUTCOME MEASURE

All-cause mortality at final follow-up.

RESULTS

Eighteen articles reporting on 16 primary clinical trials that included 4190 adults in critical or intensive care with sepsis, severe sepsis, or septic shock. A median of 70.0 g daily of pooled human albumin was received over a median of 3 days by adults with a median age of 60.8 years as part of fluid volume expansion and resuscitation, with or without correction of hypoalbuminaemia. The relative risk of death was similar between albumin groups (that received a median of 175 g in total) and control fluid groups (relative risk 0.94; 95% confidence interval 0.87 to 1.01; P=0.11; I(2)=0%). Trial sequential analysis corrected the 95% confidence interval for random error (0.85 to 1.02; D(2)=0%). Eighty eight per cent of the required information size (meta-analysis sample size) of 4894 patients was achieved, and the cumulative effect size measure (z score) entered the futility area, supporting the notion of no relative benefit of albumin (GRADE quality of evidence was moderate). Evidence of no difference was also found when albumin was compared with crystalloid fluid (relative risk 0.93; 0.86 to 1.01; P=0.07; I(2)=0%) in 3878 patents (GRADE quality of evidence was high; 79.9% of required information size) or colloid fluids in 299 patients (relative risk 1.04; 0.79 to 1.38; P=0.76; I(2)=0%) (GRADE quality of evidence was very low; 5.8% of required information size). When studies at high risk of bias were excluded in a predefined subgroup analysis, the finding of no mortality benefit remained, and the cumulative z score was just outside the boundary of futility. Overall, the meta-analysis was robust to sensitivity, subgroup, meta-regression, and trial sequential analyses.

CONCLUSIONS

In this analysis, human albumin solutions as part of fluid volume expansion and resuscitation for critically unwell adults with sepsis of any severity (with or without baseline hypoalbuminaemia) were not robustly effective at reducing all-cause mortality. Albumin seems to be safe in this setting, as a signal towards harm was not detected, but this analysis does not support a recommendation for use.

Albumin administration in the acutely ill: what is new and where next?

Albumin solutions have been used worldwide for the treatment of critically ill patients since they became commercially available in the 1940s. However, their use has become the subject of criticism and debate in more recent years. Importantly, all fluid solutions have potential benefits and drawbacks. Large multicenter randomized studies have provided valuable data regarding the safety of albumin solutions, and have begun to clarify which groups of patients are most likely to benefit from their use. However, many questions remain related to where exactly albumin fits within our fluid choices. Here, we briefly summarize some of the physiology and history of albumin use in intensive care before offering some evidence-based guidance for albumin use in critically ill patients.

Reappraising the role of albumin for resuscitation

PURPOSE OF REVIEW

Fluid resuscitation is a common intervention in acute medical practice. The optimum fluid for resuscitation remains hotly debated and it is likely to vary from one clinical situation to another. Human albumin solutions have been available since the 1940s, but their use varies greatly around the world. This review examines the current evidence for and against the use of albumin as a resuscitation fluid.

RECENT FINDINGS

Fluid resuscitation with albumin has been compared to resuscitation with saline in large high-quality trials in adult ICU patients and in African children. Within overall equivalent effects, albumin may offer a slight mortality benefit in adult ICU patients with severe sepsis whilst increasing mortality in patients with traumatic brain injury. There are no recent high-quality trials comparing albumin to synthetic colloid solutions. In African children with febrile illness and compensated shock, the effects of bolus resuscitation with albumin and saline are similar, but both increase mortality compared to treatment that avoids fluid boluses.

SUMMARY

Fluid resuscitation with albumin is well tolerated and produces similar results to resuscitation with saline. Albumin should be avoided in patients with traumatic brain injury; possible benefits in adults with severe sepsis remain to be confirmed.

Effects of Storage Solutions on the Viability of Human Umbilical Cord Mesenchymal Stem Cells for Transplantation

Human umbilical cord-derived mesenchymal stem cell (UC-MSC) transplantation has shown promise for the treatment of various diseases. For clinical applications, UC-MSCs have been stored in 0.9% saline, 5% dextrose, dextrose and sodium chloride injection, Plasma-Lyte A, 1% human serum albumin (1% HSA), or 5% HSA before administration, but the effect of storage conditions on the viability and biological function of the cells remains unknown. Freshly harvested UC-MSCs were resuspended and incubated in these solutions for 2, 4, or 6 h at 4°C or room temperature (24°C). Cell viability, apoptotic/necrotic fraction, poststorage growth potential, immunophenotype, immunosuppressive capacity, and differentiation capacity were analyzed. When stored in parenteral solutions, UC-MSCs showed progressive deterioration in survival viability and adhesion ability. After 6-h storage, the best viability and attachment rate of UC-MSCs decreased to 83.0 ± 1.6% and 71.8 ± 3.2%, respectively. Our results suggested that UC-MSCs in these conditions lose their viability in a short time. However, it seems that the other biological functions of the surviving UC-MSCs were little affected. Since UC-MSCs suspended in these mediums lose their survival viability in a short time to levels significantly below the permissible limits (70%) by FDA, precautions need to be taken on using these solutions as suspension medium and further studies on the optimal methods for preservation are urgent.

Phase I Comparability of Recombinant Human Albumin and Human Serum Albumin

Recombinant human albumin (rHA) is a highly purified animal-, virus-, and prion-free product developed as an alternative to human serum albumin (HSA), to which it is structurally equivalent. The present investigation compared the safety, tolerability, and pharmacokinetics/pharmacodynamics of rHA with HSA. Two double-blind, randomized trials were performed in healthy volunteers using intramuscular (IM) and intravenous (IV) administration. The IM trial included 500 volunteers, each receiving 5 repeat doses of 5 mg (100 subjects), 15 mg (100 subjects), or 65 mg (300 subjects) of rHA or HSA. Thirty volunteers participated in the IV trial, each receiving ascending doses (10 g, 20 g, and 50 g) of either rHA or HSA. In both trials, all adverse events were recorded and conventionally classified; potential allergic responses were also monitored. Blood samples were taken in both studies to test for IgG or IgE antibodies against test products and potential impurities. For the IV study, pharmacokinetic/pharmacodynamic assessments were performed, including measurement of serum albumin, colloid osmotic pressure, and hematocrit pre- and postinfusion. Nine subjects in the IM study (4 recipients of rHA and 5 of HSA) reported drug-related, potentially allergic events; all but 2 of these were skin related. No serious or potentially allergic events were reported with either product in the IV study. There was no immunological response to either product, and dose level did not influence the study outcomes. Serum albumin, colloid osmotic pressure changes, and hematocrit ratio were as expected, with no differences between rHA and HSA. rHA and HSA exhibited similar safety, tolerability, and pharmacokinetic/pharmacodynamic profiles, with no evidence of any immunological response.

Human Albumin Solution Resuscitation in Severe Sepsis and Septic Shock

There has been a recent resurgence of interest in the use of human albumin solution (HAS) for the resuscitation of critically ill patients. In particular, it may be beneficial for patients with severe sepsis and septic shock. We outline the evidence for the biological plausibility of this effect, perform a meta-analysis of randomised controlled trials comparing the effect of HAS with other fluid resuscitation on mortality in this group of patients and discuss the likely contribution of recently completed trials in this area. We included nine trials of 1,435 patients in the meta-analysis. Although HAS resuscitation was associated with a trend to lower mortality (relative risk 0.90, 95% confidence interval 0.79–1.02), we found that most trials reported to date are small and of variable methodological quality. The questions of a potential differential effect of dose on outcome and the pharmacological variability of HAS products have not been adequately addressed to date. We conclude that the routine administration of HAS to patients with severe sepsis and septic shock is difficult to justify on the basis of current knowledge.

Removal of TSE agent from plasma products manufactured in the United Kingdom

BACKGROUND AND OBJECTIVES

The outbreak of vCJD in the UK leads to concern regarding the potential for human-to-human transmission of this agent. Plasma-derived products such as albumin, immunoglobulin and coagulation factors were manufactured by BPL from UK plasma up until 1999 when a switch to US plasma was made. In the current study, the capacity of various manufacturing processes that were in use both prior to and after this time to remove the TSE agent was tested.

MATERIALS AND METHODS

Small-scale models of the various product manufacturing steps were developed. Intermediates were spiked with scrapie brain extract and then further processed. Samples were assayed for the abnormal form of prion protein (PrP(SC) ) by Western blotting, and the reduction in the amount of scrapie agent determined.

RESULTS

Many of the manufacturing process steps produced significant reduction in the scrapie agent. Particularly effective were steps such as ethanol fractionation, depth filtration, ion-exchange and copper chelate affinity chromatography. Virus retentive filters, of nominal pore size 15 or 20 nm, removed >3 log. The total cumulative reduction capacity for individual products was estimated to range from 7 to 14 log. In the case of factor VIII (8Y), the total removal was limited to 3 log.

CONCLUSION

All the processes showed a substantial capacity to remove the TSE agent. However, this was more limited for the intermediate purity factor VIII 8Y which included fewer manufacturing steps.

Purification of IgG and albumin from human plasma by aqueous two phase system fractionation

The current shortages in human plasma products at global levels justify the development of new, cost effective plasma fractionation methods. We have developed a fractionation process to obtain immunoglobulin G (IgG) and albumin-enriched fractions based on polymer-salt aqueous two phase system (ATPS). A small-scale (0.02 L) ATPS composed of polyethyleneglycol 3350 (PEG), potassium phosphate and sodium chloride, at pH 6.1, was evaluated and subjected to 50-fold scale-up (1 L). Further purification of the fractions was performed using caprylic acid precipitation and ion exchange chromatography. Similar yield and purity were obtained at both small and large scales. IgG precipitated in the PEG rich upper phase at 83% recovery and 2.75-fold purification factor. An 81% pure albumin fraction was obtained in the salt rich bottom phase with a 91% yield. After polishing, IgG was obtained at a recovery of 70% and a purity of 92%. Corresponding values for albumin were 91% and 90%. This IgG and albumin fractionation technology deserves further evaluation as it may represent a potential alternative to conventional plasma fractionation methods.

Enhanced bonding strength of a novel tissue adhesive consisting of cholesteryl group-modified gelatin and disuccinimidyl tartarate

The bonding strength and biocompatibility of a novel tissue adhesive consisting of cholesteryl group-modified gelatin and disuccinimidyl tartarate was evaluated. The approach was based on hydrophobically-modified gelatin to enhance the penetration of an adhesive into tissue. Disuccinimidyl tartarate was used to cross-link the cholesteryl group-modified gelatin. The cholesteryl group-modified gelatin was prepared by partially converting the gelatin amino groups with cholesteryl chloroformate. The bonding strength was evaluated by mixing cholesteryl group-modified gelatin and unmodified gelatin with the fixed amino groups/active ester groups of disuccinimidyl tartarate. The bonding strength of the resulting tissue adhesive was 1.7 times greater than the commercial aldehyde-based adhesive. The level of inflammation transcription factor, nuclear factor-kappa B, of the new tissue adhesive was significantly lower compared to the aldehyde-based adhesive after subcutaneous implantation. These results indicate that hydrophobic groups, such as cholesteryl, enhance tissue penetration as well as increase the bonding strength of tissue adhesive without a negative effect on the biocompatibility.

Release of proteolytic activity following reduction in therapeutic human serum albumin containing products: detection with a new neoepitope endopeptidase immunoassay

Botulinum type A toxin (BoNT/A) is defined by its specific endopeptidase cleavage of SNAP25 between Gln(197) and Arg(198) under reducing conditions. The neurotoxin is widely used for therapeutic or cosmetic purposes, but should not contain other toxin serotypes or unwanted protease activities. Using a neoepitope endopeptidase immunoassay, additional cleavage between Arg(198) and Ala(199) was detected with a range of therapeutic BoNT/A products confirming an earlier report of an unidentified proteolytic component. By developing the assay and making it insensitive to BoNT/C1, any activity due to the type C1 toxin was excluded. Therapeutic preparations consist of ng quantities of toxin protein which are typically stabilised by 0.125-30 mg of HSA. An excellent correlation (R(2)=0.993) between HSA content per vial and measured activity was obtained within the therapeutic BoNT/A products tested. No activity was detected in any of the non-albumin formulated preparations, thereby identifying HSA as the source of the unknown protease for the first time. To investigate the cause of this activity, either as an intrinsic molecular activity of albumin or due to an albumin-associated purification contaminant, further studies on a variety of commercial plasma-derived HSA products or recombinant HSA materials free from potential plasma contaminants were carried out. The measured proteolytic levels were highly consistent amongst preparations, and could all be partially inhibited by the presence of zinc and blocked by PKSI-527 and aprotinin. By contrast, the data did not support the role of plasmin, kallikrein, trypsin, α(2)-antiplasmin-plasmin complexes or HSA purification contaminants, PKA (prekallikrein activator) or kallikrein-like activity. Taken together, these findings indicate a new intrinsic proteolytic activity of the albumin molecule revealed under reducing conditions as the source of the unexpected Arg-Ala cleaving activity.

Characterization of peptides and proteins in commercial HSA solutions

HSA solutions account for 14% of the world market for plasma products. Albumin is indicated for reestablishing and maintaining circulatory volume in situations resulting from traumatic shock, surgery, or blood loss. Albumin is also used in extracorporeal liver support devices that perform blood dialysis against this protein. However, the protein composition of therapeutic albumin is only partially known. We performed an exhaustive analysis of albumin composition using a proteomic approach. Low abundance proteins and peptides in these samples were concentrated using a strong anion exchange resin. The absorbed material was eluted with a stepwise gradient of ammonium trifluoroacetate and the protein fraction was digested and analyzed by multidimensional liquid chromatography coupled to ESI-MS/MS using a linear ion trap. A total of 1219 peptides corresponding to 141 proteins different from albumin were identified with a false discovery rate <1%. Near 50% of these proteins have been described previously as forming part of the albuminome. Some of these proteins are proteases (kallikrein) or protease inhibitors (kininogen and SRPK1) or have relevant functions in cell surface adhesion (selectin, cadherins, and ICAMs) or in immunity and defense (molecules of the complement system and attractin). Characterization of these proteins and peptides is crucial in order to understand the therapeutic and possible deleterious effects of albumin therapies, in which this solution is infused to treat different pathological conditions.

Effect of processing methods on colouration of human serum albumin preparations

Human serum albumin is a well tolerated therapeutic for the treatment of hypovolemia. Despite all commercial human albumin preparations being derived from plasma, these products can have a highly variable colour. Albumin samples derived from ethanol precipitation and chromatographic fractionation procedures were evaluated for bilirubin and biliverdin levels and by spectrophotometry. It was shown that albumin derived from a chromatographic process, which had a bilirubin:albumin ratio similar to that observed in plasma, had a vibrant yellow appearance. The albumin derived from ethanol precipitation had undetectable levels of bilirubin, and the amber colour of this product was attributed mainly to residual haem. The presence of bilirubin during pasteurisation led to oxidation to biliverdin, with a resultant colour change from yellow to yellow/green. Given that the antioxidant properties of bilirubin are well established, it is possible that bilirubin helps protect albumin from oxidation during the pasteurisation step.

A comparative pharmacokinetic study of recombinant human serum albumin with plasma-derived human serum albumin in patients with liver cirrhosis

We conducted an open-label, parallel-group study of the high purity, mass-produced recombinant human serum albumin (rHSA), derived from the methylotrophic yeast Pichia pastoris, to compare pharmacokinetics and ensure bioequivalence with plasma-derived human serum albumin (pHSA) in 22 patients with liver cirrhosis. Both rHSA and pHSA groups enrolled 11 patients each, assigned according to predose serum albumin concentrations using the minimization method. Pharmacokinetic and safety profiles for 3-day repeated intravenous infusions at a daily dose of 25 g were evaluated for 8 days. Geometric mean AUC(0-168hr) (g.hr/dL) was 637.12 and 635.93 in the rHSA and pHSA groups, respectively, with a 90% confidence interval (CI) for the difference (92.9%-108.1%) lying within the bioequivalence range. The other major parameter, geometric mean C(max) (g/dL), was 4.16 and 4.19 in the rHSA and pHSA groups, respectively, with a 90% CI for the difference (92.7%-106.4%). The pHSA group presented with 3 adverse events: 1 case of insomnia, and 2 laboratory abnormalities with no serious adverse events. Results from this study show similar pharmacokinetic profiles following intravenous administration of 25g/day of rHSA and pHSA for 3 days, indicating bioequivalence.

Ratiometric analysis of fluorescence lifetime for probing binding sites in albumin with near-infrared fluorescent molecular probes

A number of diseases have been linked to abnormal conformation of albumin, a major extracellular protein in blood. Current protein structural analysis requires pure isolated samples, thereby limiting their use for albumin analysis in blood. In this study, we report a new approach for high-throughput structure-related analysis of albumin by using the fluorescence lifetime properties of near-infrared (NIR) polymethine dyes. Based on molecular modeling, polymethine dyes are bound to two binding sites with different polarities on albumin. As a result, an NIR molecular probe exhibits two distinct lifetimes with two corresponding fluorescent fractional contributions. The distribution of fractional contributions along with individual fluorescence lifetimes represents unique parameters for characterizing albumin architecture by ratiometric analysis. After screening a small library of NIR polymethine dyes, we identified and used a polymethine dye with optimal fluorescence lifetime properties to assess structure-related differences in commercially available bovine serum albumin as model systems. The results show that changes in the lifetime of NIR dyes reflect the perturbation of the tertiary structures of albumin and that albumin prepared by different methods has slightly altered tertiary structures. Because of the reduced absorption of light by blood in the NIR region, the method developed can be used to determine structural changes in albumin in whole blood without prior isolation of the pure protein.

Safety and efficacy of albumin administration in trauma

Albumin is one of the oldest known and studied human proteins. It is characterised by diverse physiological and biochemical properties that render it relevant to many aspects of the disordered vascular and cellular functions after trauma. Apart from the ability to maintain the colloid oncotic pressure, human serum albumin has multiple effects, including antioxidant activity and binding affinity for drugs and toxic substances, inhibition of apoptosis and modulation of trauma-induced inflammatory response. According to the current state of knowledge, there are conflicting results regarding the benefits of albumin administration in critically ill patients. Further investigations are warranted to resolve the continued uncertainty about the safety and efficacy of human serum albumin in specific clinical circumstances and selected populations of severely injured patients.

Volume expansion with albumin compared to gelofusine in children with severe malaria: results of a controlled trial

OBJECTIVES

Previous studies have shown that in children with severe malaria, resuscitation with albumin infusion results in a lower mortality than resuscitation with saline infusion. Whether the apparent benefit of albumin is due solely to its colloidal properties, and thus might also be achieved with other synthetic colloids, or due to the many other unique physiological properties of albumin is unknown. As albumin is costly and not readily available in Africa, examination of more affordable colloids is warranted. In order to inform the design of definitive phase III trials we compared volume expansion with Gelofusine (succinylated modified fluid gelatin 4% intravenous infusion) with albumin.

DESIGN

This study was a phase II safety and efficacy study.

SETTING

The study was conducted at Kilifi District Hospital, Kenya.

PARTICIPANTS

The participants were children admitted with severe falciparum malaria (impaired consciousness or deep breathing), metabolic acidosis (base deficit > 8 mmol/l), and clinical features of shock.

INTERVENTIONS

The interventions were volume resuscitation with either 4.5% human albumin solution or Gelofusine.

OUTCOME MEASURES

Primary endpoints were the resolution of shock and acidosis; secondary endpoints were in-hospital mortality and adverse events including neurological sequelae.

RESULTS

A total of 88 children were enrolled: 44 received Gelofusine and 44 received albumin. There was no significant difference in the resolution of shock or acidosis between the groups. Whilst no participant developed pulmonary oedema or fluid overload, fatal neurological events were more common in the group receiving gelatin-based intervention fluids. Mortality was lower in patients receiving albumin (1/44; 2.3%) than in those treated with Gelofusine (7/44; 16%) by intention to treat (Fisher's exact test, p = 0.06), or 1/40 (2.5%) and 4/40 (10%), respectively, for those treated per protocol (p = 0.36). Meta-analysis of published trials to provide a summary estimate of the effect of albumin on mortality showed a pooled relative risk of death with albumin administration of 0.19 (95% confidence interval 0.06-0.59; p = 0.004 compared to other fluid boluses).

CONCLUSIONS

In children with severe malaria, we have shown a consistent survival benefit of receiving albumin infusion compared to other resuscitation fluids, despite comparable effects on the resolution of acidosis and shock. The lack of similar mortality benefit from Gelofusine suggests that the mechanism may involve a specific neuroprotective effect of albumin, rather than solely the effect of the administered colloid. Further exploration of the benefits of albumin is warranted in larger clinical trials.

Renal impact of fluid management with colloids: a comparative review

BACKGROUND AND OBJECTIVES

Colloids such as hydroxyethyl starch (HES), gelatin, dextran and albumin are useful for maintaining renal perfusion and function. The comparative renal effects of colloids have not been previously reviewed.

METHODS

Computer searches of the MEDLINE and EMBASE bibliographic databases and the Cochrane Library were conducted using the search terms: colloids; hetastarch; gelatin; dextrans; serum albumin; kidney failure; cardiac surgical procedures; and kidney transplantation. Relevant studies were also sought through hand searching and examination of reference lists. Results of identified studies were qualitatively summarized with account taken for potential confounding factors.

RESULTS

The three artificial colloids HES, gelatin and dextran all exhibited troublesome renal side-effects. Randomized trials have demonstrated adverse renal effects of HES in sepsis and surgery. Undesirable renal effects are common to all available HES solutions regardless of molecular weight, substitution or C2/C6 ratio. While some of its effects may be less severe than those of HES, gelatin also can adversely affect the kidney. A negative renal impact of dextran is well-established, although this colloid is now less extensively used than formerly. As the normal endogenous colloid, albumin exhibits a wide margin of renal safety, although albumin overdose needs to be avoided. Albumin also appears to exert protective effects on the kidney such as inhibition of apoptosis and scavenging of reactive oxygen species.

CONCLUSIONS

Colloids display important differences in their actions on the kidney. These contrasting renal effects should be considered in making fluid management decisions.