Ligand reactivity and allosteric regulation of hemoglobin-based oxygen carriers

Ronda, Luca; Bruno, Stefano; Abbruzzetti, Stefania; Viappiani, Cristiano; Bettati, Stefano

doi:10.1016/j.bbapap.2008.04.021

Cited by 22 publications

(12 citation statements)

References 201 publications

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“…[ 24,25 ] As a Food and Drug Administration (FDA) approved polymer for human use in drug and cosmetic applications, [ 24 ] PEG has also been widely investigated for tissue engineering, including ophthalmic applications. [ 26 ] For such applications, PEG is often combined with natural materials such as collagen or cell adhesion ligands such as RGD (Arginine-Glycine-Aspartic amino acid sequence common in proteins such as collagen and fi bronectin) for improved cell-surface interactions and attachment.…”

Section: Introductionmentioning

confidence: 99%

Biodegradable and Biocompatible Poly(Ethylene Glycol)‐based Hydrogel Films for the Regeneration of Corneal Endothelium

Özçelık

Brown

Blencowe

et al. 2014

Adv Healthcare Materials

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Corneal endothelial cells (CECs) are responsible for maintaining the transparency of the human cornea. Loss of CECs results in blindness, requiring corneal transplantation. In this study, fabrication of biocompatible and biodegradable poly(ethylene glycol) (PEG)-based hydrogel films (PHFs) for the regeneration and transplantation of CECs is described. The 50-μm thin hydrogel films have similar or greater tensile strengths to human corneal tissue. Light transmission studies reveal that the films are >98% optically transparent, while in vitro degradation studies demonstrate their biodegradation characteristics. Cell culture studies demonstrate the regeneration of sheep corneal endothelium on the PHFs. Although sheep CECs do not regenerate in vivo, these cells proliferate on the films with natural morphology and become 100% confluent within 7 d. Implantation of the PHFs into live sheep corneas demonstrates the robustness of the films for surgical purposes. Regular slit lamp examinations and histology of the cornea after 28 d following surgery reveal minimal inflammatory responses and no toxicity, indicating that the films are benign. The results of this study suggest that PHFs are excellent candidates as platforms for the regeneration and transplantation of CECs as a result of their favorable biocompatibility, degradability, mechanical, and optical properties.

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Section: Introductionmentioning

confidence: 99%

Biodegradable and Biocompatible Poly(Ethylene Glycol)‐based Hydrogel Films for the Regeneration of Corneal Endothelium

Özçelık

Brown

Blencowe

et al. 2014

Adv Healthcare Materials

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“…33 This stabilization of relaxed state by PEG's hydration shell or modifications that help the transition of Hb from T to R conformation may be responsible for the lowering of p50. 13 However, in the current method of conjugation, it is not feasible to know about which amino group perturbation is critical for lowering the p50 of Hb molecules and thus the lowering of the p50 of the final conjugates. 34 Interestingly, increasing the concentration of the PEG did not significantly lower the p50, which is contrary to our initial assumptions based on reports from the literature.…”

Section: Discussionmentioning

confidence: 99%

“…Polymerization and crosslinking offer a practical way to alter p50 that depends on the crosslinking agent and may be mediated by chemistry of the conjugation. 13 A typical approach described in the literature (glutaraldehyde as a conjugating agent) resulted in high p50, which is more relevant in normal conditions than the low p50 conditions encountered at the sites of transplantation. 14 Also, glutaraldehyde crosslinking is shown to promote unwanted effect of vasoconstriction 15 and release of the polymeric linker by degradation exhibiting cytotoxicity.…”

Section: Introductionmentioning

confidence: 98%

Hemoglobin Conjugates with Antioxidant Enzymes (Hemoglobin-Superoxide Dismutase-Catalase) via Poly(Ethylene Glycol) Crosslinker for Protection of Pancreatic Beta RINm5F Cells in Hypoxia

Nadithe

Bae

2011

Tissue Engineering Part A

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A low p50 hemoglobin (Hb) (p50 indicates O(2) tension at which Hb is half-saturated)-based oxygen carrier conjugated to antioxidant enzymes via dicarboxymethylated poly(ethylene glycol) (PEG) linker may have the beneficial effect in protecting pancreatic beta cells from severe hypoxia at transplantation sites. In this study, the oxygen dissociation curves, Hill plots, Bohr Effect, and oxygen content of Hb conjugates were measured. The protective effect due to incubation of Hb-conjugates (Hb/PEG molar ratio 1:10) with pancreatic beta cells (RINm5F) against hypoxia (6%, 3%, and 1% oxygen) was evaluated by an MTT assay and confocal microscopy. Quantitatively, Hb conjugates with antioxidant enzymes offered statistically significant protection (p<0.01, increased viability ∼80%) from hypoxia compared to control cells in 1% oxygen environment. Confocal images also showed that the low p50 Hb conjugates with antioxidants protected RINm5F cells from hypoxia.

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“…Conversely, the chemically linked Hb–SOD products described by Alagic [4] and Tarasov [5] have cross‐links introduced at different residues, as well as reactive groups, which must be blocked in a separate step. In these chemical linking approaches, usually both intra‐tetramer and inter‐tetramer bonds are introduced, with the involvement of multiple side chains [23]. In addition, it has been shown that shorter cross‐links may provide better stabilized Hb [24].…”

Section: Discussionmentioning

confidence: 99%

A superoxide dismutase–human hemoglobin fusion protein showing enhanced antioxidative properties

et al. 2009

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Much of the toxicity of Hb has been linked to its redox activity; Hb may generate reactive oxygen species, such as the superoxide anion. Superoxide is intrinsically toxic, and superoxide dismutase (SOD) provides important cellular protection. However, if the Hb molecule is located outside the red blood cell, the normal protection systems involving SOD and catalase are no longer closely associated with it, exposing Hb and its cellular surroundings to oxidative damage. In order to produce less toxic Hb molecules, we have explored gene fusion to obtain homogeneous SOD–Hb conjugates. The chimeric protein was generated by coexpressing the human Hb α‐chain/manganese SOD gene together with the β‐chain gene in Escherichia coli. We show that the engineered SOD–Hb fusion protein retains the oxygen‐binding capacity and, moreover, decreases cytotoxic ferrylHb (HbFe4+) formation when challenged with superoxide radicals. The SOD–Hb fusion protein also exhibits a 44% lower autoxidation rate and higher thermal stability than Hb alone.

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Ligand reactivity and allosteric regulation of hemoglobin-based oxygen carriers

Cited by 22 publications

References 201 publications

Biodegradable and Biocompatible Poly(Ethylene Glycol)‐based Hydrogel Films for the Regeneration of Corneal Endothelium

Biodegradable and Biocompatible Poly(Ethylene Glycol)‐based Hydrogel Films for the Regeneration of Corneal Endothelium

Hemoglobin Conjugates with Antioxidant Enzymes (Hemoglobin-Superoxide Dismutase-Catalase) via Poly(Ethylene Glycol) Crosslinker for Protection of Pancreatic Beta RINm5F Cells in Hypoxia

A superoxide dismutase–human hemoglobin fusion protein showing enhanced antioxidative properties

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