Polyoxazoline-conjugated porcine serum albumin as an artificial plasma expander for dogs

Abstract

Veterinary medicine has made tremendous progress for domestic dogs, which are irreplaceable family members enriching human life. Nevertheless, no adequate supply system exists for their blood products. This study examined the synthesis, structure, safety, and efficacy of poly(2-ethyl-2-oxazoline)-conjugated porcine serum albumin (POx-PSA) as an artificial plasma expander for dogs. The aqueous POx-PSA solution showed moderately high colloid osmotic pressure and good blood cell compatibility. Actually, lyophilized powder stored for 1 year can regenerate into a homogeneous solution. The circulation half-life of POx-PSA in rats was 2.1-fold longer than that of naked PSA. Rats produced neither anti-PSA IgG antibody nor anti-POx IgG antibody, which suggests excellent immunological stealth properties of POx-PSA. Complete resuscitation of hemorrhagic shock in rats was achieved soon after injection of POx-PSA solution. Serum biochemistry tests and histopathological observations indicated no abnormality in the related organs. When POx-PSA was administered to dogs intravenously, (i) no serum biochemical or hematological alteration was observed, also (ii) no overt deterioration of animal health was observed. These results indicate that POx-PSA has potential as an artificial plasma expander for dogs.

Poly(2-ethyl-2-oxazoline)-Conjugated Hemoglobins as a Red Blood Cell Substitute

“…The diameters are markedly larger than those of the naked Hb (6.2 nm) and HbA (6.4 nm). The POx layer thickness (approximately 3 nm) was in good agreement with that of other POx-protein . The CD spectral pattern of Hb resembled that of HbA, whereas the minimum CD intensities at 208 nm were slightly different (Figure C).…”

“…The POx layer thickness (approximately 3 nm) was in good agreement with that of other POx-protein. 47 The CD spectral pattern of Hb resembled that of HbA, whereas the minimum CD intensities at 208 nm were slightly different (Figure 1C). This finding suggests that their secondary structures are not equal.…”

“…Therefore, we chose maleimide-thiol coupling. A unique sulfhydryl-group-terminated POx, POx-SH, was synthesized by the coupling of POx (Mw: 5 kDa) with 3,3′-dithiodipropionic acid followed by reduction of the middle disulfide bond (Figure A) . As a core protein, we used porcine Hb, as obtained from porcine RBCs of specific pathogen-free (SPF) swine using the procedures that we reported earlier. , A cross-linker, N -succinimidyl 3-maleimidopropionate (SMP), was reacted with Hb surface lysines to yield maleimido-activated Hb (MA-Hb).…”

“…The experiments using Wistar rats (male, 8 weeks of age, 247 ± 7 g weight, total n = 15) were conducted according to the previously reported protocols with some modifications. , Details are described in the Supporting Information.…”

“…Given that background, poly­(2-ethyl-2-oxazoline) (POx) has attracted attention as a potential alternative to PEG. , Its physicochemical features such as nonionicity, chain flexibility, and high solubility in various solvents are comparable to those of PEG. Indeed, POx-conjugated proteins and enzymes showed a long blood circulation lifetime and sufficient safety while preserving their medical effects. − Actually, the POx shielding can camouflage the immunogenicity of the protein. It is noteworthy that this polymer is excreted rapidly by kidneys with no accumulation in tissues .…”