Interactions of Alginate-Deferoxamine Conjugates With Blood Components and Their Antioxidation in the Hemoglobin Oxidation Model

Fluorene methoxycarbonyl-PEG-deferoxamine conjugates "hitchhike" with albumin in situ for iron overload therapy

Although deferoxamine (DFO) has been approved for the treatment the iron overloaded diseases, its clinical application is impeded by very short circulation time and its relating toxicity. In this work, the fluorene methoxycarbonyl (FMOC) for "albumin hitchhiking" was used to prolong the plasma circulation time of DFO and reduce toxicity. The designed FMOC-PEG-DFO conjugates were found to reversible bind to albumin and gradually release DFO in vivo. Herein, the FMOC-PEG₁₀₀₀-DFO conjugates could increase 30 times the blood circulation time of DFO with the improvement of the iron elimination efficacy. Meanwhile, the conjugates markedly reduced the cytotoxicity of DFO. Taken together, the result demonstrated the FMOC-PEG₁₀₀₀-DFO conjugates could be a potential therapeutic choice for iron-overload-related diseases.

Alginate as a Promising Biopolymer in Drug Delivery and Wound Healing: A Review of the State-of-the-Art

Biopolymeric nanoparticulate systems hold favorable carrier properties for active delivery. The enhancement in the research interest in alginate formulations in biomedical and pharmaceutical research, owing to its biodegradable, biocompatible, and bioadhesive characteristics, reiterates its future use as an efficient drug delivery matrix. Alginates, obtained from natural sources, are the colloidal polysaccharide group, which are water-soluble, non-toxic, and non-irritant. These are linear copolymeric blocks of α-(1→4)-linked l-guluronic acid (G) and β-(1→4)-linked d-mannuronic acid (M) residues. Owing to the monosaccharide sequencing and the enzymatically governed reactions, alginates are well-known as an essential bio-polymer group for multifarious biomedical implementations. Additionally, alginate’s bio-adhesive property makes it significant in the pharmaceutical industry. Alginate has shown immense potential in wound healing and drug delivery applications to date because its gel-forming ability maintains the structural resemblance to the extracellular matrices in tissues and can be altered to perform numerous crucial functions. The initial section of this review will deliver a perception of the extraction source and alginate’s remarkable properties. Furthermore, we have aspired to discuss the current literature on alginate utilization as a biopolymeric carrier for drug delivery through numerous administration routes. Finally, the latest investigations on alginate composite utilization in wound healing are addressed.

Glucose-responsive multifunctional metal-organic drug-loaded hydrogel for diabetic wound healing

As the incidence of diabetes increases, its complication, diabetic foot ulcers, has become the main type of clinically chronic refractory wounds. Due to the hyperglycemic microenvironment of the diabetic wound, which leads to vascular defects and bacterial growth, the therapeutic effect of wound dressings lacking strategic design is relatively limited. In this study, we designed an injectable, "self-healing", and glucose-responsive multifunctional metal-organic drug-loaded hydrogel (DG@Gel) for diabetic wound healing. The functionalized hydrogel was prepared by phase-transfer-mediated metallo-nanodrugs, which were made by co-assembling zinc ions, organic ligands, and a small-molecule drug, deferoxamine mesylate (DFO), and the programmed loading of glucose oxidase (GOX). When injected into a diabetic wound, the GOX in DG@Gel changed the hyperglycemic wound microenvironment by decomposing excess glucose into hydrogen peroxide and glucuronic acid, which decreased the pH of the wound site. The low pH promoted the release of zinc ions and DFO, which exhibited synergistic antibacterial and angiogenesis activity for diabetic wound repair. In vitro experiments revealed the antibacterial activity and the cell proliferation, migration, and tube formation ability of DG@Gel. Moreover, in vivo experiments showed that DG@Gel can induce re-epithelialization, collagen deposition, and angiogenesis during wound healing in diabetic mice with good biocompatibility and biodegradability. The results suggest that this hydrogel is a promising innovative dressing for the treatment of diabetic wounds. STATEMENT OF SIGNIFICANCE: Diabetic ulcers, as one of the main types of chronic refractory wounds, are not treated effectively in the clinic due to a lack of strategic approach. In this study, we designed a glucose-responsive multifunctional metal-organic drug-loaded hydrogel (DG@Gel), which can change the hyperglycemic wound microenvironment by decomposing excess glucose into hydrogen peroxide and glucuronic acid. This in turn promoted the release of zinc ions and deferoxamine mesylate (DFO) in the hydrogel, which exhibited synergistic antibacterial and angiogenic activity for diabetic wound repair. Furthermore, the DG@Gel exhibited good biocompatibility and biodegradability in vivo. In general, this innovative strategy design may have great application potential in the treatment of various chronic wounds.

Synthetic Materials that Affect the Extracellular Matrix via Cellular Metabolism and Responses to a Metabolic State

In regenerative medicine and tissue engineering, many materials are developed to mimic the extracellular matrix (ECM). However, these ECM-mimicking materials do not yet completely recapitulate the diversity and complexity of biological tissue-specific ECM. In this review, an alternative strategy is proposed to generate ECM, namely synthesizing a material that functions as a drug delivery system, releasing molecules that target cellular metabolic pathways and thereby stimulate the local cells to create their own ECM. This is based on the fact that ECM synthesis, modification, composition, signaling, stiffness, and degradation are modulated by cellular metabolism. Metabolism can be targeted at different levels, ranging from modulating the availability of substrates or co-factors to regulating the activity of essential transcription factors. Depending on the drug of interest, its characteristics, mechanism of action, cellular target, and application, a different drug delivery system should be designed. Metabolic drugs modulating the ECM require cellular uptake for their function, therefore reversible linkers are recommended. Preferably the metabolic modulators are only released when needed, which will be upon a specific metabolic state, a change in ECM stiffness, or ECM remodeling. Therefore, reversible linkers that respond to an environmental stimulus could be incorporated. All in all, a novel strategy is suggested to develop a tissue-specific ECM by generating a synthetic material that releases metabolic molecules modulating the ECM. Various ways to modulate the ECM properties via the metabolism are reviewed and guidelines for the development of these materials are provided.

PEGylation of Deferoxamine for Improving the Stability, Cytotoxicity, and Iron-Overload in an Experimental Stroke Model in Rats

Deferoxamine (DFO) is a widely used drug for the treatment of iron-overload-related diseases in the clinic. However, its inherent shortcomings, such as a short plasma half-life and cytotoxicity, need to be addressed to widen its clinical utility. In this study, PEGylated DFO was first synthesized, and its chemical structure was characterized, and then in vitro and in vivo studies were performed. The metabolism assay showed that the stability of the PEGylated DFO was significantly improved, with a half-life 20 times greater than DFO. Furthermore, the PEGylated DFO exhibited significantly lower cytotoxicity compared with DFO. Additionally, the hemocompatibility assay showed that the PEGylated DFO had no significant effect on the coagulation system, red blood cells, complement, and platelets. In vivo studies indicated that PEGylated DFO was capable of reducing the iron accumulation, degeneration of neurons, and promotion of functional recovery. Taken together, PEGylated DFO improved stability, cytotoxicity, and iron-overload in an experimental stroke model in rats, making it a promising therapy for treating iron-overload conditions in the clinic.