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A serious concern of doxorubicin (DOX) therapy is that it causes severe adverse effects, particularly cardiotoxicity. Carbon monoxide (CO) possesses powerful cytoprotective effects against drug-induced organ injury and is expected to ameliorate DOX-induced cardiotoxicity. In this study, a dual carrier of DOX and CO (CO-HemoAct-DOX) was fabricated based on a haemoglobin–albumin cluster (HemoAct), which is a protein cluster with a haemoglobin core structure wrapped by serum albumin. CO-HemoAct-DOX was synthesised by binding CO to a haemoglobin core and covalently conjugating (6-maleimidocaproyl)hydrazone derivative of DOX to an albumin shell. The average DOX/cluster ratio was about 2.6. In the in vitro cytotoxicity assay against cancer cells, the anti-tumour activity of CO-HemoAct-DOX was 10-fold lower than that of DOX in a 2D-cultured model, whereas CO-HemoAct-DOX suppressed the growth of tumour spheroids to the same extent as DOX in the 3D-cultured model. In colon-26 tumour-bearing mice, CO-HemoAct-DOX achieved DOX delivery to the tumour site and alleviated tumour growth more effectively than DOX. Furthermore, CO-HemoAct attenuated DOX-induced cardiomyocyte atrophy in H9c2 cells and elevated the levels of cardiac biomarkers in mice exposed to DOX. These results suggest that the dual delivery of CO and DOX using HemoAct is a promising strategy as an anti-tumour agent to realise well-tolerated cancer therapy with minimal cardiotoxicity. [ABSTRACT FROM AUTHOR]

Apohemoprotein is focused on the field of theranostics, serving as a porphyrin carrier. Hemoglobin (Hb) consists of α2β2 tetramer with iron(II)‐protoporphyrin IX (heme) bound to each globin. However, heme‐removed Hb (apoHb) causes dissociation at αβ interfaces and aggregation under physiological conditions. We synthesized a stable apoHb derivative comprising intramolecular‐crosslinked apoHb (apoXHb) and human serum albumin (HSA), apoXHb‐HSA3. ApoXHb‐HSA3 engendered no aggregates in the physiological solutions. Moreover, apoXHb‐HSA3 was reconstituted with zinc(II)‐protoporphyrin IX (ZnP), generating ZnXHb‐HSA3, a potent photosensitizer for photodynamic therapy (PDT). The photophysical properties of ZnXHb‐HSA3 were identical to those of zinc‐substituted XHb (ZnXHb). Cellular uptake behavior was evaluated using various cancer cell lines. ZnXHb‐HSA3 released ZnP around the cells, and the free ZnP penetrated cell membranes. In contrast, protein units were not observed within the cells. ZnXHb‐HSA3 showed no cytotoxicity under dark conditions and demonstrated superior PDT activity in comparison to naked ZnXHb. ZnXHb‐HSA3 acts as an innovative porphyrin carrier for enhanced PDT. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Myoglobin combined with human serum albumin (Mb‐HSA) can be produced using yeast Pichia pastoris as a host strain, with secretion into the culture medium. This Mb‐HSA fusion protein possesses identical O2 binding affinity to that of naked Mb. The Mb unit is reconstituted with a zinc(II) protoporphyrin IX, yielding (zinc substituted Mb)‐HSA, ZnMb‐HSA. The photophysical property and singlet O2 generation ability of ZnMb‐HSA are equivalent to those of ZnMb. In vitro cell experiments revealed that ZnMb‐HSA acts as a superior photosensitizer for photodynamic cancer therapy. It is noteworthy that ZnMb‐HSA shows long circulation lifetime in vivo. [ABSTRACT FROM AUTHOR]

A bovine hemoglobin (HbBv) or human adult hemoglobin (HbA) wrapped covalently by human serum albumins (HSAs), hemoglobin–albumin clusters (HbBv–HSA3 and HbA–HSA3), are artificial O2 carriers used as a red blood cell substitute. This article describes the physicochemical properties of the HbBv–HSA3 and HbA–HSA3 solutions, and their abilities to restore the systemic condition after resuscitation from hemorrhagic shock in anesthetized rats. The HbBv–HSA3 and HbA–HSA3, which have high colloid osmotic activity, showed equivalent solution characteristics and O2 binding parameters. Shock was induced by 50% blood withdrawal. Rats exhibited hypotension and significant metabolic acidosis. After 15 min, the rats were administered shed autologous blood (SAB), HbBv–HSA3, HbA–HSA3, or Ringer's lactate (RL) solution. Survival rates, circulation parameters, hematological parameters, and blood gas parameters were monitored during the hemorrhagic shock and for 6 h after administration. All rats in the SAB, HbBv–HSA3, and HbA–HSA3 groups survived for 6 h. The HbBv–HSA3 and HbA–HSA3 groups restored mean arterial pressure after the resuscitation. No remarkable difference was observed in the time courses of blood gas parameters in any resuscitated group except for the RL group. Serum biochemical tests showed increases in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the HbBv–HSA3 and HbA–HSA3 groups compared to the SAB group. Therefore, we observed other rats awakened after resuscitation with HbA–HSA3 for 7 days. The blood cell count, AST, and ALT recovered to the baseline values by 7 days. All the results implied that HbBv–HSA3 and HbA–HSA3 clusters provide restoration from hemorrhagic shock as an alternative material for SAB transfusion. [ABSTRACT FROM AUTHOR]

The additional new mutations designed for manipulating the architecture of heme pocket in recombinant human serum albumin (rHSA)-heme complexes by altering distal amino acids are described. The replacement of polar Arg-186 with Leu or Phe has increased the hydrophobicity of the distal environment, has yielded a complex with reduced [O.sub.2] binding affinity, which is almost the same as that of human red blood cells and therefore better tuned to a role in [O.sub.2] transport.