Application Of Nitric Oxide Delivery System In Drug Combination

Nitric oxide（NO）,as an important signaling molecule in vivo,participates in the regulation of various signaling pathways in physiology and plays a vital role in the occurrence and development of numerous diseases,such as cardiovascular disease,wound,inflammation,gastrointestinal diseases,stroke,immune system,and tumors.The potential of NO in drug combinations has been the highlight.However,as a gas molecule,the poor stability and short half-life of NO limit the direct clinical application.Furthermore,the activity of NO,which relies on the delivery system,depends upon the dose,the place and the time.Due to the different microenvironments in diseases,formulating a reasonable plan for the combined application of NO delivery systems and drugs is particularly important,which can benefit NO to achieve precise treatment in diseases.Therefore,in this article,we established different NO delivery systems for tumors and wound treatments.We first explored the application of NO delivery system combined with doxorubicin in reversing multidrug-resistant tumors,which are features of rich reactive oxygen species（ROS）and over-expressive P-glycoprotein.NO can facilitate chemotherapy drugs more sensitive to tumors by reducing the expression of P-glycoprotein.Therefore,we designed a ROS-responsive multifunctional nitric oxide delivery material（TPE-RSNO）,which is composed of hydrophilic S-nitrosated peptide and hydrophobic aggregation-induced emission group,and then we combined it with doxorubicin in reversing multidrug-resistant tumors.The optical,physical and chemical characterization showed that TPE-RSNO retained the properties of NO donor and fluorescence at the same time.Besides,TPE-RSNO presented good ROS responsiveness,which could self-assemble into micelles with a weak fluorescent background in an aqueous solution.However,ROS stimulation accelerated the release of NO and the cross-linking of S-S,which drove the formation of strong fluorescent aggregates.Moreover,TPE-RSNO could detect exogenous NO while imaging the tumor due to the fluorescence intensity being closely related to the release behavior of NO.Meanwhile,TPE-RSNO showed good biocompatibility and a great effect of reversing tumor multidrug resistance in cells.The IC₅₀ of doxorubicin in drug-resistant tumor cells was 95.4μg/m L,while the IC₅₀ of TPE-RSNO combined with doxorubicin was 6.75μg/m L.The combination treatment of TPE-RSNO and doxorubicin also displayed high efficiency for inhibiting tumor growth and good safety in tumor-bearing immunodeficient mice.The results of confocal imaging and histological immunological analysis revealed that the combined application of TPE-RSNO and doxorubicin inhibited the tumor since TPE-RSNO could effectively deliver NO to the tumor for reducing the expression of P-glycoprotein,which leaded to chemotherapy sensitization and induced the accumulation of doxorubicin in the tumor.As a consequence,the combination treatment could inhibit tumor proliferation and reverse tumor drug resistance effectively.We also explored the application of NO delivery system combined with antioxidant edaravone in repairing diabetic wounds.Due to the high levels of ROS in diabetic wound microenvironment,moreover,NO and edaravone can both play a role to promote wound healing through different mechanisms,so we have developed a NO donor（S-nitrosoglutathione,GSNO）and edaravone loading nanocomposite hydrogel delivery system.The GSNO-loaded and edaravone-loaded nanoparticles were prepared by solvent replacement and solvent evaporation methods.The physical and chemical characterization presented that the nanoparticles were spherical with good distribution,and the positively charged nanoparticles could be further cross-linked with the negatively charged alginic acid to form a nanocomposite hydrogel.The release kinetics experiment indicated that the delivery system could slowly and continuously release edaravone and GSNO successively.The NO nanocomposite hydrogel and NO combined with edaravone nanocomposite hydrogel presented excellent potential to promote wound healing in diabetic mice.In further investigation,the NO delivery system performed a great behavior of accelerating wound healing in both normal and diabetic models,which could promote the nitrosation of proteins in human fibroblasts with good biocompatibility.Histological results showed that it could accelerate healing through promoting the formation of fibroblasts,new blood vessels and collagen deposition.In addition,the effect of the edaravone delivery system is connected with the concentration.Suitable dosage edaravone could remove the appropriate amount of ROS,accomplished the transition from chronic to acute wound and promoted combined application effect with NO delivery system in the wound.On the contrary,excessive edaravone was not conducive to wound healing.In summary,we have respectively developed a nitric oxide delivery system adapted to the tumor and the wound according to their characteristic microenvironment,and formulated a suitable plan for drug combination with nitric oxide delivery system.The combination treatment strategy showed good effects in the two disease models of tumor and wound,which not only offered a new treatment suggestion for wound healing and reversal of tumor multidrug resistance,but also provided a novel idea for NO in the treatment of other diseases.