A thrombus is composed of fibrin, activated platelets and leukocytes and the formation of an occlusive thrombus is a critical pathophysiological feature of numerous cardiovascular diseases. Here, self-immolative prodrug (Fu-sBR) nanoassemblies are developed for targeted on-demand therapy for thrombotic disorders. Fu-sBR nanoassemblies target P-selectin on activated platelets and exert antioxidant, anti-inflammatory and antiplatelet activities to suppress thrombus formation. This is reported by Dongwon Lee and co-workers in article number 2000273.

Mortality and morbidity after cardiac arrest remain high due to ischemia/reperfusion (I/R) injury causing multi-organ damages, even after successful return of spontaneous circulation. We previously generated H2O2-activatable antioxidant nanoparticles formulated with copolyoxalate containing vanillyl alcohol (PVAX) to prevent I/R injury. In this study, we examined whether PVAX could effectively reduce organ damages in a rat model of whole-body ischemia/reperfusion injury (WBIR). To induce a cardiac arrest, 70µl/100 g body weight of 1 mmol/l potassium chloride was administered via the jugular venous catheter. The animals in both the vehicle and PVAX-treated groups had similar baseline blood pressure. After 5.5 minutes of cardiac arrest, animals were resuscitated via intravenous epinephrine followed by chest compressions. PVAX or vehicle was injected after the spontaneous recovery of blood pressure was noted, followed by the same dose of second injection 10 minutes later. After 24 hours, multiple organs were harvested for pathological, biochemical, molecular analyses. No significant difference on the restoration of spontaneous circulation was observed between vehicle and PVAX groups. Analysis of organs harvested 24 hours post procedure showed that whole body I/R significantly increased reactive oxygen species (ROS) generation, inflammatory markers, and apoptosis in multiple organs (heart, brain, and kidney). PVAX treatment effectively blocked ROS generation, reduced the elevation of pro-inflammatory cytokines, and decreased apoptosis in these organs. Taken together, our results suggest that PVAX has potent protective effect against WBIR induced multi-organ injury, possibly by blocking ROS-mediated cell damage.

Formation of an occlusive thrombus is a critical pathophysiological feature of numerous cardiovascular diseases. Thrombosis is promoted by P‐selectin overexpressed on activated platelets and endothelium and tightly linked with the overproduction of hydrogen peroxide (H 2 O 2 ). The overexpression of P‐selectin and overproduction of H 2 O 2 become unique features of thrombosed vessels which provide a rationale for the development of targeted therapeutics for thrombosis. In this work, targeted self‐delivering and H 2 O 2 ‐activatable antithrombotic nanomedicine (Fu–sBR) composed of a self‐immolative dimeric prodrug (sBR) and a P‐selectin targeting fucoidan, are reported. In the presence of fucoidan, sBR is formulated into stable nanoassemblies that can serve as carrier‐free nanodrugs and exert antioxidant, anti‐inflammatory, and antiplatelet activities in a H 2 O 2 ‐triggered manner. In mouse models of carotid arterial thrombosis and deep vein thrombosis (DVT), Fu–sBR nanoassemblies specifically target thrombosed vessels to effectively suppress thrombus development by inhibiting the expression of tumor necrosis factor‐alpha (TNF‐α), interleukine‐1 beta (IL‐1β), and soluble CD40 ligand (sCD40L). Given their self‐delivering capability, thrombus targeting ability, and stimulus‐activatable therapeutic actions, Fu–sBR nanoassemblies have great translational potential as therapeutic agents for various thrombotic disorders.

Background Ischemia/reperfusion (I/R) injury causes overproduction of reactive oxygen species, which are the major culprits of oxidative stress that leads to inflammation, apoptosis, myocardial damage, and dysfunction. Bilirubin acts as a potent endogenous antioxidant that is capable of scavenging various reactive oxygen species. We have previously generated bilirubin nanoparticles (BRNPs) consisting of polyethylene glycol–conjugated bilirubin. In this study, we examined the therapeutic effects of BRNPs on myocardial I/R injury in mice. Methods and Results In vivo imaging using fluorophore encapsulated BRNPs showed BRNPs preferentially targeted to the site of I/R injury in the heart. Cardiac I/R surgery was performed by first ligating the left anterior descending coronary artery. After 45 minutes, reperfusion was achieved by releasing the ligation. BRNPs were administered intraperitoneally at 5 minutes before and 24 hours after reperfusion. Mice that received BRNPs showed significant improvements in their cardiac output, assessed by echocardiogram and pressure volume loop measurements, compared with the ones that received vehicle treatment. BRNPs treatment also significantly reduced the myocardial infarct size in mice that underwent cardiac I/R, compared with the vehicle‐treatment group. In addition, BRNPs effectively suppressed reactive oxygen species and proinflammatory factor levels, as well as the amount of cardiac apoptosis. Conclusions Taken together, BRNPs could exert their therapeutic effects on cardiac I/R injury through attenuation of oxidative stress, apoptosis, and inflammation, providing a novel therapeutic modality for myocardial I/R injury.

Neuropeptide-Y (NPY) leads to angiogenesis and remodeling of the ischemic myocardium. The objective of this study is to assess the therapeutic potential of NPY in a model of acute myocardial ischemia using a nanoparticles delivery system targeted to tissue with oxidative stress. NPY3-36 was loaded onto copolyoxalate containing vanillyl alcohol (PVAX) using a double emulsification strategy. Adult C57BL/J6 mice (n = 49) were randomly divided into PVAX-NPY3-36 (n = 22), Vehicle (Saline) (n = 16), and Sham (n = 11) groups. The ischemia to left anterior descending artery was induced in PVAX-NPY3-36 or vehicle groups. The tissue was collected at the end of two weeks after assessing the functional and echocardiographic data. There was a significant decrease in infarction size and mortality in PVAX-NPY3-36 group compared to the Vehicle group (P = 0.01 and P = 0.05). On echocardiography, there was significant improvement in contractility and diastolic parameters (P = 0.01). On pressure-volume loop there was significant increase in stroke volume (P = 0.01), cardiac output (P = 0.01) and ventricular stroke work (P = 0.01) in the PVAX-NPY3-36 group. On Western blot analysis, there was a significant increase in pro-angiogenic factors Ang-1, TGF-β, PDGF- β and its receptors and VEGF in the ischemic tissue treated with PVAX-NPY3-36 as compared to Vehicle ischemic tissue (P = 0.01, P = 0.0003, and P < 0.05 respectively). It may be possible to have targeted delivery of labile neurotransmitters NPY3-36 to the ischemic myocardium using nanoparticle PVAX and achieving angiogenesis and significant functional improvement.

Inflammatory responses associated with ischemia/reperfusion injury (IRI) play a central role in alloimmunity and transplant outcomes. A key event driving these inflammatory responses is the burst of reactive oxygen species (ROS), with hydrogen peroxide (H2 O2 ) as the most abundant form that occurs as a result of surgical implantation of the donor organ. Here, we used a syngeneic rat renal transplant and IRI model to evaluate the therapeutic properties of APP-103, a polyoxalate-based copolymer molecule containing vanillyl alcohol (VA) that exhibits high sensitivity and specificity toward the production of H2 O2 . We show that APP-103 is safe, and that it effectively promotes kidney function following IRI and survival of renal transplants. APP-103 reduces tissue injury and IRI-associated inflammatory responses in models of both warm ischemia (kidney clamping) and prolonged cold ischemia (syngeneic renal transplant). Mechanistically, we demonstrate that APP-103 exerts protective effects by specifically targeting the production of ROS. Our data introduce APP-103 as a novel, nontoxic, and site-activating therapeutic approach that effectively ameliorates the consequences of IRI in solid organ transplantation.

Purpose: Our data introduce APP-103 as a novel, non-toxic and site-activating therapeutic approach that effectively ameliorates the consequences of ischemia/reperfusion injury in solid organ transplantation. Methods: A key event driving inflammatory responses to ischemia/reperfusion injury (IRI) is the burst of reactive oxygen species. APP-103 exhibits a high sensitivity and specificity towards the local production of H2O2. We used an IRI and syngeneic transplant model to evaluate antioxidant and anti-inflammatory properties of APP-103 and downstream effects on alloimmunity and fibrosis. Results: In a warm ischemia model, IRI was induced in rats by clamping the left renal pedicle for 45 minutes followed by reperfusion. Control animals exhibited a dramatic increase in serum creatinine (SCrea) levels by 24 h, while animals treated with a single dose APP-103 (3 mg/kg) 10 minutes prior to IRI induction showed significantly reduced SCrea levels. Histological analysis confirmed that treated animals were protected against IRI-induced tissue injuries. We next delineated the effects of APP in more detail in a syngeneic kidney transplantation model with a cold ischemia time (CIT) of 6 h. APP-103 or phosphate buffer saline (PBS) was administered IV at 15 mg/kg 1 h prior to injury and after + 2 h. Treatment with APP-103 significantly reduced SCrea levels on post-operative day 1 (1.39±0.15 vs. 2.16±0.27 p,= 0.019). Histopathology assessment of the transplanted kidney grafts revealed tubular injury and fibrosis with extensive chronic tubule-interstitial changes, dilation of tubules, diffuse interstitial fibrosis only in vehicle-treated animals on POD 1. Mechanistically, we identified an ameliorated oxidative stress by dihydroethidium (DHE) staining in renal transplants when treating animals with APP-103 treated animals. Moreover, kidneys from APP-103 treated animals demonstrated reduced intragraft mRNA expression of relevant pro-inflammatory cytokines (pro-inflammatory cytokines TNF-a and IL-6, inhibition of T cell proliferation cytokine IL-2, and a significant increase of the anti-inflammatory cytokine IL-10). Conclusions: We demonstrate that APP-103 is safe and effectively reducing kidney function both, short and long-term. APP-103 represses local ROS and reduces pro-inflammatory cytokines following IRI. Our data support the clinical application of APP for the mitigation of delayed graft function (DGF).

Cardiovascular diseases (CVDs) have become prominent in mortality and morbidity rates. Prevalent cardiovascular conditions, such as hypertension, atherosclerosis and oxidative stress, are increasing at an alarming rate. Conventional drugs have been associated with adverse effects, suggesting a need for an alternative measure to ameliorate CVD. A number of plant- and herb-derived preventative food and therapeutic drugs for cardiovascular conditions are progressively used for their various benefits. Naturally derived food and drugs have fewer side effects because they come from natural elements; preventative food, such as grape seed, inhibits changes of histopathology and biomarkers in vital organs whereas therapeutic drugs, for instance Xanthone, improve heart functions by suppressing oxidative stress of myocyte. This review closely examines the various plant- and herb-derived drugs that have assumed an essential role in treating inflammation and oxidative stress for prevalent cardiovascular conditions. Furthermore, the use of plant-derived medicine with other synthetic particles, such as nanoparticles, for targeted therapy is investigated for its effective clinical use in the future.

You have accessJournal of UrologyTransplantation & Vascular Surgery: Renal Transplantation & Vascular Surgery I1 Apr 2018PD25-08 THE POLYMER PRO-DRUG APP-103 MITIGATES I/R INJURY AND IMPROVES GRAFT FUNCTION IN A PRE-CLINICAL RENAL TRANSPLANT MODEL Koichiro Minami, Abdallah Elkhal, Soochan Bae, Jake Reder, Brandy Houser, Peter M Kang, and Stefan G Tullius Koichiro MinamiKoichiro Minami More articles by this author , Abdallah ElkhalAbdallah Elkhal More articles by this author , Soochan BaeSoochan Bae More articles by this author , Jake RederJake Reder More articles by this author , Brandy HouserBrandy Houser More articles by this author , Peter M KangPeter M Kang More articles by this author , and Stefan G TulliusStefan G Tullius More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.1335AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Ischemia-reperfusion injury (IRI) is the strongest non-HLA factor that augments allogenicity of transplanted organs. Damage subsequent to IRI is critically linked to an abundance of reactive oxygen species (ROS), including H202 that initiates inflammation and significantly contributes to allograft loss. Antioxidant Polymer Prodrugs, or APPsTM, are potent, site-specific, self-limiting therapeutics that mitigate inflammation by reducing localized oxidative stress. APPs are innovative, highly effective, and safe antioxidative and anti-inflammatory therapies. Here we show APP-103 to mitigate IRI injury incurred during transplant surgery by reducing inflammation and improving graft function. METHODS Lew kidneys kept at 4°C until transplanted. Recipients received APP-103 (i.v./15mg/Kg) or vehicle (PBS); time for anastomosis was 25±5 minutes. Kidney function was assessed by serum creatinine (SCrea) measured at days 1 and 7 after transplantation. Local inflammation was determined by histology and qPCR for pro-and anti-inflammatory cytokines. Dosing at -1 and +2hrs after transplant was based on pharmacokinetic studies that revealed a 3-hr half-life for APP-103. RESULTS APP-103 ameliorated IRI in prior studies of warm ischemia (kidney, heart and limb injury). Here we demonstrate that APP-103 restores graft function following renal transplantation in syngeneic rat models by early mitigation of inflammatory responses. Recipients treated with APP-103 had 40% improved graft function (SCrea at days 1 and 7). Pathological analysis confirmed a significant reduction in interstitial fibrosis and tubular atrophy on POD days 1 and 7. Extended cold ischemia conditions were also mitigated by APP-103 with >50% SCrea reduction. Treatment with APP-103 resulted in reduced intragraft mRNA levels of the pro-inflammatory cytokines TNF-α and IL-6, inhibition of T cell proliferation cytokine IL-2, and a significant increase of the anti-inflammatory cytokine IL-10. Of further clinical relevance, APP-103 had no associated toxicity at the highest administrable dose. CONCLUSIONS APP-103 is a novel and safe therapeutic that targets on-site ROS showing impressive preservation of graft structure and function while dampening the initial inflammatory response linked to IRI. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e549 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Koichiro Minami More articles by this author Abdallah Elkhal More articles by this author Soochan Bae More articles by this author Jake Reder More articles by this author Brandy Houser More articles by this author Peter M Kang More articles by this author Stefan G Tullius More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Purpose Ischemia-reperfusion injury (IRI) is the strongest non-HLA factor that augments allogenicity of transplanted organs. Damage subsequent to IRI is critically linked to an abundance of reactive oxygen species (ROS), including H202 that initiates inflammation and significantly contributes to allograft loss. Antioxidant Polymer Prodrugs, or APPs™, are potent, site-specific, self-limiting therapeutics that mitigate inflammation by reducing localized oxidative stress. APPs are innovative, highly effective, and safe antioxidative and anti-inflammatory therapies. Here, we show that APP-103 is able to mitigate IRI incurred during transplant surgery by reducing inflammation and improving graft function. Methods Lew kidneys were stored at 4°C after procurement. Recipients received APP-103 (i.v./15mg/Kg) or vehicle (PBS); time for anastomosis was 25±5 minutes. Kidney function was assessed by serum creatinine (SCrea) measured at days 1 and 7 after transplantation. Local inflammation was determined by histology and qPCR for pro-and anti-inflammatory cytokines. Dosing at -1 and +2hrs after transplant was based on pharmacokinetic studies that revealed a 3-hr half-life for APP-103. Results APP-103 ameliorated IRI in prior studies of warm ischemia (kidney, heart and limb injury). Here, we demonstrate that APP-103 restores graft function following renal transplantation in syngeneic rat models by early mitigation of inflammatory responses. Recipients treated with APP-103 had 40% improved graft function (SCrea at days 1 and 7). Pathological analysis confirmed a significant reduction in interstitial fibrosis and tubular atrophy on POD days 1 and 7. Extended cold ischemia conditions were also mitigated by APP-103 with >50% SCrea reduction. Treatment with APP-103 resulted in reduced intragraft mRNA levels of the pro-inflammatory cytokines TNF-a and IL-6, inhibition of T cell proliferation cytokine IL-2, and a significant increase of the anti-inflammatory cytokine IL-10.Of further clinical relevance, APP-103 had no associated toxicity at the highest administrable dose. Flow cytometry revealed a significant decrease in surface expression of activation and maturation markers including CD40, CD80, and CD86 on DCs treated with APP-103 during stimulation with LPS. Moreover, flow cytometry indicated that frequencies of CD4+ and CD8+ IFNγ+ cells were significantly reduced when DCs were cocultivated in presence of APP-103. Conclusion APP-103 is a novel and safe therapeutic that targets on-site ROS showing impressive preservation of graft structure and function while dampening the initial inflammatory response linked to IRI.

Inami, Koichiro M. MD, PhD; Elkhal, Abdala PhD; Weins, Astrid MD, PhD; Bae, Soochan PhD; Houser, Brandy PhD; Kang, Peter M. MD; Tullius, Stefan G. MD, PhD, FACS Author Information

Wearable and implantable devices require conductive, stretchable and biocompatible materials. However, obtaining composites that simultaneously fulfil these requirements is challenging due to a trade-off between conductivity and stretchability. Here, we report on Ag–Au nanocomposites composed of ultralong gold-coated silver nanowires in an elastomeric block-copolymer matrix. Owing to the high aspect ratio and percolation network of the Ag–Au nanowires, the nanocomposites exhibit an optimized conductivity of 41,850 S cm −1 (maximum of 72,600 S cm −1 ). Phase separation in the Ag–Au nanocomposite during the solvent-drying process generates a microstructure that yields an optimized stretchability of 266% (maximum of 840%). The thick gold sheath deposited on the silver nanowire surface prevents oxidation and silver ion leaching, making the composite biocompatible and highly conductive. Using the nanocomposite, we successfully fabricate wearable and implantable soft bioelectronic devices that can be conformally integrated with human skin and swine heart for continuous electrophysiological recording, and electrical and thermal stimulation.

We generated a novel nanoparticle called PVAX, which has intrinsic antiapoptotic and anti-inflammatory properties. This nanoparticle was loaded with neuropeptide Y3-36 (NPY3-36), an angiogenic neurohormone that plays a central role in angiogenesis. Subsequently, we investigated whether PVAX-NPY3-36 could act as a therapeutic agent and induce angiogenesis and vascular remodeling in a murine model of hind limb ischemia. Adult C57BL/J6 mice (n = 40) were assigned to treatment groups: control, ischemia PBS, ischemia PVAX, ischemia NPY3-36, and Ischemia PVAX-NPY3-36 Ischemia was induced by ligation of the femoral artery in all groups except control and given relevant treatments (PBS, PVAX, NPY3-36, and PVAX-NPY3-36). Blood flow was quantified using laser Doppler imaging. On days 3 and 14 posttreatment, mice were euthanized to harvest gastrocnemius muscle for immunohistochemistry and immunoblotting. Blood flow was significantly improved in the PVAX-NPY3-36 group after 14 days. Western blot showed an increase in angiogenic factors VEGF-R2 and PDGF-β (P = 0.0035 and P = 0.031, respectively) and antiapoptotic marker Bcl-2 in the PVAX-NPY3-36 group compared with ischemia PBS group (P = 0.023). Proapoptotic marker Smad5 was significantly decreased in the PVAX-NPY3-36 group as compared with the ischemia PBS group (P = 0.028). Furthermore, Y2 receptors were visualized in endothelial cells of newly formed arteries in the PVAX-NPY3-36 group. In conclusion, we were able to show that PVAX-NPY3-36 can induce angiogenesis and arteriogenesis as well as improve functional blood flow in a murine model of hind limb ischemia.NEW & NOTEWORTHY Our research project proposes a novel method for drug delivery. Our patented PVAX nanoparticle can detect areas of ischemia and oxidative stress. Although there have been studies about delivering angiogenic molecules to areas of ischemic injury, there are drawbacks of nonspecific delivery as well as short half-lives. Our study is unique because it can specifically deliver NPY3-36 to ischemic tissue and appears to extend the amount of time therapy is available, despite NPY3-36's short half-life.

Background During myocardial ischemia/reperfusion (I/R), a large amount of reactive oxygen species (ROS) is produced. In particular, overproduction of hydrogen peroxide (H2O2) is considered to be a main cause of I/R‐mediated tissue damage. We generated novel H2O2‐responsive antioxidant polymer nanoparticles (PVAX and HPOX) that are able to target the site of ROS overproduction and attenuate the oxidative stress‐associated diseases. In this study, nanoparticles were examined for their therapeutic effect on myocardial I/R injury. Methods and Results The therapeutic effect of nanoparticles during cardiac I/R was evaluated in mice. A single dose of PVAX (3 mg/kg) showed a significant improvement in both cardiac output and fraction shortening compared with poly(lactic‐coglycolic acid) (PLGA) particle, a non‐H2O2‐activatable nanoparticle. PVAX also significantly reduced the myocardial infarction/area compared with PLGA (48.7±4.2 vs 14.5±2.1). In addition, PVAX effectively reduced caspase‐3 activation and TUNEL‐positive cells compared with PLGA. Furthermore, PVAX significantly decreased TNF‐α and MCP‐1 mRNA levels. To explore the antioxidant effect of PVAX by scavenging ROS, dihydroethidium staining was used as an indicator of ROS generation. PVAX effectively suppressed the generation of ROS caused by I/R, whereas a number of dihydroethidium‐positive cells were observed in a group with PLGA I/R. In addition, PVAX significantly reduced the level of NADPH oxidase (NOX) 2 and 4 expression, which favors the reduction in ROS generation after I/R. Conclusions Taken together, these results suggest that H2O2‐responsive antioxidant PVAX has tremendous potential as a therapeutic agent for myocardial I/R injury.

Therapeutic angiogenesis has achieved promising results for ischemic diseases or peripheral artery disease in preclinical and early-phase clinical studies. We examined the therapeutic angiogenic effects of HPOX, which is biodegradable polymer composing the antioxidant p-hydroxybenzyl alcohol (HBA), in a mouse model of hindlimb ischemia. HPOX effectively stimulated blood flow recovery, compared with its degraded compounds HBA and 1,4-cyclohexendimethanol, via promotion of capillary vessel density in the ischemic hindlimb. These effects were highly correlated with levels of angiogenic inducers, vascular endothelial cell growth factor (VEGF), heme oxygenase-1 (HO-1), and Akt/AMPK/endothelial nitric oxide synthase (eNOS) in ischemic mouse hindlimb muscle. Blood perfusion and neovascularization induced by HPOX were reduced in eNOS−/− and HO-1+/− mice. HPOX also elevated the endothelial cell markers VEGF receptor-2, CD31, and eNOS mRNAs in the ischemic hindlimb, indicating that HPOX increases endothelial cell population and angiogenesis in the ischemic muscle. However, this nanoparticle suppressed expression levels of several inflammatory genes in ischemic tissues. These results suggest that HPOX significantly promotes angiogenesis and blood flow perfusion in the ischemic mouse hindlimb via increased angiogenic inducers, along with suppression of inflammatory gene expression. Thus, HPOX can be used potentially as a noninvasive drug intervention to facilitate therapeutic angiogenesis.

Overproduction of hydrogen peroxide (H2O2) causes oxidative stress and is the main culprit in the pathogenesis of ischemia/reperfusion (I/R) injury. Suppression of oxidative stress is therefore critical in the treatment of I/R injury. Here, we report H2O2-activatable antioxidant prodrug (BRAP) that is capable of specifically targeting the site of oxidative stress and exerting anti-inflammatory and anti-apoptotic activities. BRAP with a self-immolative boronic ester protecting group was designed to scavenge H2O2 and release HBA (p-hydroxybenzyl alcohol) with antioxidant and anti-inflammatory activities. BRAP exerted potent antioxidant and anti-inflammatory activity in lipopolysaccharide (LPS)- and H2O2-stimulated cells by suppressing the generation of ROS and pro-inflammatory cytokines. In mouse models of hepatic I/R and cardiac I/R, BRAP exerted potent antioxidant, anti-inflammatory and anti-apoptotic activities due to the synergistic effects of H2O2-scavenging boronic esters and therapeutic HBA. In addition, administration of high doses of BRAP daily for 7 days showed no renal or hepatic function abnormalities. Therefore BRAP has tremendous therapeutic potential as H2O2-activatable antioxidant prodrug for the treatment of I/R injuries.

During myocardial ischemia/reperfusion (I/R), a large amount of reactive oxygen species (ROS) is produced which causes oxidative stress and leads to severe cellular and tissue damage. In particular, overproduction of hydrogen peroxide (H2O2) is considered as a main cause of I/R-mediated tissue damage by inducing inflammation and apoptosis. Therefore, rapid elimination of H2O2 and suppression of oxidative stress are thought to be reasonable strategies to treat myocardial I/R injury. Recently, we generated novel H2O2-responsive antioxidant polymer nanoparticles (PVAX and HPOX) that are able to target the site of ROS overproduction and impede the progression of oxidative stress-associated diseases. In this study, PVAX nanoparticles were selected as therapeutic agents for myocardial I/R injury based on the results of direct comparison studies in vitro and in vivo. To explore therapeutic effect of PVAX on cardiac I/R injury, cardiac function 2 weeks after reperfusion was evaluated. A single dose of PVAX (3mg/kg) showed a significant improvement in both cardiac output (8.1± 0.7 vs. 3.4±0.3) and fraction shortening (43.8± 0.9 vs. 31.2±3.8) compared with poly (lactic-co-glycolic acid) (PLGA) particle, a lacking H2O2 responsible nanoparticle. Consistent with cardiac function evaluation, PVAX significantly reduced the myocardial infarction /area at risk compared with PLGA (48.7±4.2 vs.14.5±2.1). In addition, PVAX effectively reduced caspase-3 activation (2.6±0.1 vs.1.4±0.1) and TUNEL-positive cells (8.2±1.8 vs. 2.7±0.6) compared with PLGA. Furthermore, PVAX significantly decreased TNF-α (5.5±0.4 vs. 3.0±0.3) and MCP-1 (2.3±0.1 vs. 1.4±0.1) mRNA levels. To explore the antioxidant effect of PVAX by scavenging ROS, dihydroethidium (DHE) staining was used as an indicator of ROS generation. PVAX effectively suppressed the generation of ROS caused by I/R while a number of DHE-positive cells were observed in a group of PLGA I/R. In addition, PVAX significantly reduced the level of NADPH oxidase (NOX) 2 and 4 expression, which favors the reduction in ROS generation after I/R. Taken together, these results suggest that H2O2-responsive antioxidant PVAX has tremendous potential as a therapeutic agent for myocardial I/R injury.

Combretastatin A-4 phosphate (CA4P), a tubulin depolymerizing agent, shows promise in anti-cancer therapy and is associated with dose-dependent transient hypertension. The cardiac consequence of this hypertensive effect is unknown. This study was conducted to examine the cardiotoxic effect of CA4P on a rat model of hypertension. Hypertensive rats were created by feeding a 6% high salt (HS) diet to Dahl salt sensitive (DSS) rats for 2.5weeks. Cardiac toxicity was measured using serum troponin I levels 24h after CA4P administration. In rats fed HS diet, there was a significant increase in mean arterial blood pressure (MAP) from baseline, which was further increased by 80% following CA4P administration with peak systolic blood pressure (BP) of 247mmHg. Treatment with the calcium channel blockers, diltiazem and nicardipine, completely inhibited the hypertensive effects of CA4P. Nitroglycerin or enalapril, however, failed to completely block the hypertensive effects of CA4P. CA4P injection also significantly increased the cardiac troponin I level in hypertensive rats though pretreatment with diltiazem effectively blocked troponin I increase after CA4P administration. Based on these findings, an exaggerated hypertensive response to CA4P is associated with myocardial damage in hypertensive rats. Calcium channel blockers effectively blocked both CA4P induced hypertension and cardiac damage.