Synthesis and biophysical properties of polymerized human serum albumin

Abstract

The use of many plasma expanders (PEs) is often limited by undesirable side effects, such as red blood cell (RBC) aggregation (hydroxyethyl starch), nephrotoxicity (dextran), and extravasation (albumin). Despite its natural prevalence in the bloodstream, human serum albumin (HSA) can increase the risk of mortality when administered to patients with increased vascular permeability (i.e., patients suffering from burns, septic shock, and endothelial dysfunction). The harmful extravasation of HSA can be limited by polymerizing HSA to increase its molecular size. In this study, HSA was nonspecifically cross-linked with glutaraldehyde at different cross-link densities by varying the molar ratio of glutaraldehyde to HSA. The results of this study show that the weight-averaged molecular weight (MW), viscosity, and extent of RBC aggregation of polymerized HSA increases with increasing cross-link density, whereas the colloid osmotic pressure (COP) decreases with increasing cross-link density. Interestingly, circular dichroism measurements indicate that the secondary structure of HSA is unaffected by polymerization. Altogether, these results show that glutaraldehyde can effectively cross-link HSA to produce high MW polymers, yielding a novel series of potential PEs that exhibit low COP and high viscosity.

Cardiac function during resuscitation from hemorrhagic shock with polymerized bovine hemoglobin-based oxygen therapeutic

“…The design of HBOCs have evolved from an initial approach involving cell-free Hb, to a more elaborate approach, where Hb is chemically polymerized to increase its molecular size and prevent extravasation (Elmer et al 2011). Despite significant commercial efforts, recent clinical trials with polymerized hemoglobin (PolyHb) solutions hampered further development (Hess 1999, Silverman and Weiskopf 2009, Sloan et al 1999, Weiskopf 2010).…”

Small-volume resuscitation from hemorrhagic shock with polymerized human serum albumin

“…Given that volume restoration and microvascular function are special during resuscitation from hemorrhagic shock, our novel PolyHSAs, when used during small volume resuscitation, produced rapid microvascular flow and FCD and sustained recovery of blood pressure. PolyHSAs are biocompatible and do not induce RBC aggregation [10]. Our findings suggest that an increase in plasma viscosity, without necessarily restoring blood viscosity to normal with PolyHSA, is beneficial during resuscitation.…”

“…HSA polymerization has been previously published [10]. Briefly, Albuminar ® (ABO Pharmaceuticals, San Diego, CA) was diluted to 25 mg/mL with phosphate buffered saline, and 70% glutaraldehyde (Sigma Aldrich, Atlanta, GA) was then added to HSA solutions at the following molar ratios of glutaraldehyde to HSA: 24:1, 60:1, and 94:1.…”

“…Polymeric HSA (PolyHSA) MW is controlled by simply varying the molar ratio of glutaraldehyde to HSA. Payne et al was the first to increase the size of bovine serum albumin (BSA) by reacting it with various concentrations of glutaraldehyde [9, 10]. However, the resultant Schiff bases in the polymerized BSA molecules were not chemically stabilized, leaving the polymerized BSA susceptible to hydrolysis back into HSA and glutaraldehyde.…”

“…However, the resultant Schiff bases in the polymerized BSA molecules were not chemically stabilized, leaving the polymerized BSA susceptible to hydrolysis back into HSA and glutaraldehyde. Recently, PolyHSA was synthesized with chemically stabilized Schiff bases, preserving HSA secondary structure, increasing solution viscosity and decreasing COP compared to unpolymerized HSA [9, 10]. Therefore, glutaraldehyde cross-linking represents an attractive option to increase HSA size and intravascular retention.…”