Glutaraldehyde-polymerized hemoglobin and tempol (PolyHb-tempol) has superoxide dismutase activity that can attenuate oxidative stress on endothelial cells induced by superoxide anion

The Protection of Enzyme Activity for the Preparation of Humanized Polymerized Hemoglobin-Superoxide Dismutase-Catalase-Carbonic Anhydrase

This work finds suitable enzyme activity protectants to improve the recovery rate of enzyme activity in the preparation of human polymerized hemoglobin-superoxide dismutase-catalase-carbonic anhydrase (PolyHb-SOD-CAT-CA), including trehalose, sucrose, glucose, hydroxypropyl-β-cyclodextrin, and mannitol.Different types and concentrations of enzyme activity protective agents were added during polymerization to compare their protective ability to enzyme activity and the effect on the properties of hemoglobin. The study found that compared with trehalose, the protective effect of sucrose on CA enzyme activity is non-significant to that on hemoglobin, the recovery rate of SOD, and CAT enzyme activity has significant increased. Glucose, hydroxypropyl-β-cyclodextrin, and mannitol are unsuitable for the added enzyme activity protective agent of PolyHb-SOD-CAT-CA.The protective effect of sucrose on CA was non-significant with trehalose. The protective effect of sucrose on SOD and CAT enzyme activity was higher than trehalose, and the protective effect reached the maximum when the concentration reached 1.5%.

Ferrous hemoglobin and hemoglobin-based oxygen carriers acting as a peroxidase can inhibit oxidative damage to endothelial cells caused by hydrogen peroxide

Oxidative damage caused by the ferryl hemoglobin is one of the major clinical adverse reactions of hemoglobin-based oxygen carriers (HBOCs), while the production of reactive oxygen species in a pathological state can oxidize hemoglobin (HbFe²⁺ ) to ferryl Hb, which can then enter the pseudoperoxidase cycle, making hemoglobin highly toxic. In this study, we found that ferrous hemoglobin and polymerized porcine hemoglobin (one of the HBOCs) have the peroxidase activity different from the pseudoperoxidase activity of ferric hemoglobin. Ferrous hemoglobin can catalyze the reaction of tyrosine (Tyr) with hydrogen peroxide. In addition, the results also indicated that ferrous hemoglobin and pPolyHb have a strong inhibitory effect on the pseudoperoxidase activity of ferric hemoglobin. Therefore, hydrogen peroxide was consumed in a large amount, which greatly prevented hemoglobin from becoming oxidized and entering the pseudoperoxidase cycle, thus inhibiting ferryl Hb toxicity. We further cultured human umbilical vein endothelial cells and monitored cell morphology, viability, cell cycle, apoptosis, lactate dehydrogenase (LDH) release, and malondialdehydes (MDAs) formation when incubated with H₂ O₂ , Tyr, and HbFe²⁺ . HbFe²⁺ and pPolyHb reduced cell cycle arrest, apoptosis, LDH release, and MDA formation. These results showed that reducing oxidative damage induced by H₂ O₂ and converted hemoglobin from a molecule that is toxic to one that inhibits oxidative damage, suggesting a new strategy for development of a safer HBOCs.

Optimizing an Antioxidant TEMPO Copolymer for Reactive Oxygen Species Scavenging and Anti-Inflammatory Effects in Vivo

Oxidative stress is broadly implicated in chronic, inflammatory diseases because it causes protein and lipid damage, cell death, and stimulation of inflammatory signaling. Supplementation of innate antioxidant mechanisms with drugs such as the superoxide dismutase (SOD) mimetic compound 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) is a promising strategy for reducing oxidative stress-driven pathologies. TEMPO is inexpensive to produce and has strong antioxidant activity, but it is limited as a drug due to rapid clearance from the body. It is also challenging to encapsulate into micellar nanoparticles or polymer microparticles, because it is a small, water soluble molecule that does not efficiently load into hydrophobic carrier systems. In this work, we pursued a polymeric form of TEMPO [poly(TEMPO)] to increase its molecular weight with the goal of improving in vivo bioavailability. High density of TEMPO on the poly(TEMPO) backbone limited water solubility and bioactivity of the product, a challenge that was overcome by tuning the density of TEMPO in the polymer by copolymerization with the hydrophilic monomer dimethylacrylamide (DMA). Using this strategy, we formed a series of poly(DMA-co-TEMPO) random copolymers. An optimal composition of 40 mol % TEMPO/60 mol % DMA was identified for water solubility and O2•- scavenging in vitro. In an air pouch model of acute local inflammation, the optimized copolymer outperformed both the free drug and a 100% poly(TEMPO) formulation in O2•- scavenging, retention, and reduction of TNFα levels. Additionally, the optimized copolymer reduced ROS levels after systemic injection in a footpad model of inflammation. These results demonstrate the benefit of polymerizing TEMPO for in vivo efficacy and could lead to a useful antioxidant polymer formulation for next-generation anti-inflammatory treatments.

Stepping stones to the future of haemoglobin-based blood products: clinical, preclinical and innovative examples

Critical overview of the different oxygen therapeutics developed so far to be used when donor blood is not available.

Polymerized human hemoglobin increases the effectiveness of cisplatin-based chemotherapy in non-small cell lung cancer

Cisplatin is a promising therapeutic for the treatment of non-small cell lung cancer (NSCLC). Unfortunately, a significant portion of NSCLC patients relapse due to cisplatin chemoresistance. This chemoresistance is thought to be primarily associated with hypoxia in the tumor microenvironment. Administration of hemoglobin (Hb)-based oxygen (O2) carriers (HBOCs) is a promising strategy to alleviate hypoxia in the tumor, which may make cisplatin more effective. In this study, we administered a high O2 affinity, relaxed state (R-state) polymerized hemoglobin (PolyHb) to three different NSCLC cell lines cultured in vitro and implanted in vivo into healthy mice. The R-state PolyHb administered in this study is unable to deliver O2 unless under severe hypoxia which significantly limits its oxygenation potential. In vitro sensitivity studies indicate that the administration of PolyHb increases the effectiveness of cisplatin under hypoxic conditions. Additional animal studies revealed that co-administration of PolyHb with cisplatin attenuated tumor growth without alleviating hypoxia. Analysis of reactive O2 species production in the presence of hypoxic culture indicates that exogenous ROS production by oxidized PolyHb may the mechanism of chemosensitization. This ROS mechanism, coupled with oxygenation, may be a potential chemosensitizing strategy for use in NSCLC treatment.

Glutaraldehyde inactivation of enveloped DNA viruses in the preparation of haemoglobin-based oxygen carriers

Glutaraldehyde (GA), used medically as a disinfectant and as a crosslinker for haemoglobin (Hb)-based oxygen carriers (HBOCs), was investigated for its ability to inactivate viruses during the preparation of these artificial blood substitutes. Porcine parvovirus (PPV; a non-enveloped DNA virus) and porcine pseudorabies virus (PRV; an enveloped DNA virus) were used as the virus indicators. Upon treatment with 0.1 mM GA, the titer of PRV decreased from 9.62 log₁₀ to 2.62 log₁₀ within 0.5 h, whereas that of PPV decreased from 7.00 log₁₀ to 2.30 log₁₀ in 5 h. Following treatment with 1.0 mM GA, the titer of PRV decreased from 11.00 log₁₀ to 1.97 log₁₀ within 0.5 h, whereas that of PPV decreased from 7.50 log₁₀ to 3.43 log₁₀ in 4.5 h. During the polymerization of Hb with GA, the GA concentration decreased to 1.0 and 0.1 mM within 30 and 50 min, respectively, at a GA:Hb molar ratio of 10:1, whereas at a GA:Hb molar ratio of 30:1, GA decreased to those same concentrations in 1.5 and 2.5 h, respectively. This rapid decrease in GA concentration during its polymerization with Hb indicates that GA must be added into the Hb solution in a short time in order to get as high a initial concentration as possible. In this study, the GA can only inactivate PRV effectively, given that a longer time (4.5 h) was required for it to inactivate the PPV titer. This study therefore demonstrates that GA inactivates the enveloped DNA virus only during the preparation of HBOCs.