Abstract 553: In Vivo Cardioprotection by Postconditioning is Mediated by Endogenous PAR2 Activation

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Rong Jiang ◽  
Jeremiah Deneve ◽  
Shady Eldaif ◽  
Ning-Ping Wang ◽  
Zhi-Qing Zhao ◽  
...  
Keyword(s):  
Infarct Size ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
List Type ◽  
Area At Risk ◽  
General Activation ◽  
Sparing Effect ◽  
Myocardial Ischemia Reperfusion ◽  
Protease Activated Receptor 2

Background : Protease activated receptor 2 (PAR2) is a member of the seven transmembrane G-protein coupled receptor (GPCR) family. Activation of PAR2 is cardioprotective in ex vivo and in vivo myocardial ischemia reperfusion model, potentially by cognate ligands released at reperfusion (R). Postconditioning (postcon), defined as alternating brief (seconds) episodes of R and ischemia applied at the onset of R , is also cardioprotective. This cardioprotection involves activation of GPCR by adenosine, bradykinin and opioids. However, the role of the GPCR PAR2 in cardioprotection by postcon has not been investigated. Hypothesis : This study tested the hypothesis that cardioprotection by postcon is mediated in part by endogenous PAR2 activation. Methods : Rats were randomly assigned to one of 5 groups with 30 min left coronary artery (LCA) occlusion followed by 3 h reperfusion: Control: no intervention was applied either before or after LCA occlusion (n =8); Postcon alone: 3 cycles of 10-s full reperfusion and 10-s re-occlusion were initiated at the onset of R (n=8); PAR2 antagonist alone: the selective PAR2 antagonist (FSLLRY-NH2, 1 mg/Kg) was injected 5 min before R (n=8); PAR2 antagonist + Postcon: PAR2 antagonist (1 mg/Kg) was administered 5 min before Postcon (n=8); Delayed PAR2 antagonist: PAR2 antagonist (1 mg/Kg) was given 5 min after the postcon protocol (n=8). Results: Area at risk (AAR) was comparable in all groups (35–38%). Compared to control, infarct size (TTC, area of necrosis/AAR, %) was significantly reduced by postcon alone (39.0% ± 1.3% vs 53.7% ± 1.5%, P<0.05). The PAR2 antagonist alone administered just before R had no effect on infarct size (57.4% ± 2.4% vs 53.7% ± 1.5%). Interestingly, the infarct sparing effect of postcon was completely reversed by PAR2 antagonist administered before postcon to control values ( 56.7% ± 2.7% *). Furthermore, the infarct sparing effect of postcon was also blocked by PAR2 antagonist given after postcon (50.3% ± 3.3% *). These results suggest that endogenous PAR2 activation induced by postcon during the early moments of R is cardioprotective. Conclusions : Cardioprotection by postcon is mediated, in part, by activation of endogenous PAR2, and suggests a general activation of GPCR. *P<0.05 vs Postcon.

PAR-2 activation at the time of reperfusion salvages myocardium via an ERK1/2 pathway in in vivo rat hearts

2007 ◽  
Vol 293 (5) ◽  
pp. H2845-H2852 ◽  
Author(s):  
Rong Jiang ◽  
Amanda Zatta ◽  
Hajime Kin ◽  
Ningping Wang ◽  
James G. Reeves ◽  
...  
Keyword(s):  
Infarct Size ◽  
Kinase Inhibitor ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Myocardial Infarct Size ◽  
Protective Effects ◽  
Rat Hearts ◽  
Sparing Effect ◽  
Myocardial Ischemia Reperfusion

Protease-activated receptor-2 (PAR-2) may have proinflammatory effects in some tissues and protective effects in other tissues. The role of PAR-2 in in vivo myocardial ischemia-reperfusion has not yet been determined. This study tested the hypothesis that PAR-2 activation with the PAR-2 agonist peptide SLIGRL (PAR-2 AP) reduces myocardial infarct size when given at reperfusion in vivo, and this cardioprotection involves the ERK1/2 pathway. Anesthetized rats were randomly assigned to the following groups with 30 min of regional ischemia and 3 h reperfusion: 1) control with saline; 2) vehicle (DMSO); 3) PAR-2 AP, 1 mg/kg given intravenously 5 min before reperfusion; 4) scrambled peptide (SP), 1 mg/kg; 5) the ERK1/2 inhibitor PD-98059 (PD), 0.3 mg/kg given 10 min before reperfusion; 6) the phosphatidylinositol 3-kinase inhibitor LY-294002 (LY), 0.3 mg/kg given 10 min before reperfusion; 7) PD + PAR-2 AP, 0.3 mg/kg PD given 5 min before PAR-2 AP; 8) LY + PAR-2 AP, 0.3 mg/kg LY given 5 min before PAR-2 AP; 9) chelerythrine (Chel) alone, 5 mg/kg given 10 min before reperfusion; and 10) Chel + PAR-2 AP, Chel was given 5 min before PAR-2 AP (10 min before reperfusion). Activation of ERK1/2, ERK5, Akt, and the downstream targets of ERK1/2 [P90 RSK and bcl-xl/bcl-2-associated death promoter (BAD)] was determined by Western blot analysis in separate experiments. PAR-2 AP significantly reduced infarct size compared with control (36 ± 2% vs. 53 ± 1%, P < 0.05), and SP had no effect on infarct size (53 ± 3%). PAR-2 AP significantly increased phosphorylation of ERK1/2, p90RSK, and BAD but not Akt or ERK5. Accordingly, the infarct-size sparing effect of PAR-2 AP was abolished by PD (PAR-2 AP, 36 ± 2% vs. PD + PAR-2 AP, 50 ± 1%; P < 0.05) and by Chel (Chel + PAR-2 AP, 58 ± 2%) but not by LY (PAR-2 AP, 36 ± 2% vs. LY + PAR-2 AP, 38 ± 3%; P > 0.05). Therefore, PAR-2 activation is cardioprotective in the in vivo rat heart ischemia-reperfusion model, and this protection involves the ERK1/2 pathway and PKC.

Long-term infusion of Met5-enkephalin fails to protect murine hearts against ischemia-reperfusion injury

2005 ◽  
Vol 288 (4) ◽  
pp. H1717-H1723 ◽  
Author(s):  
Koh Kuzume ◽  
Kazuyo Kuzume ◽  
Zhiping Cao ◽  
Lijuan Liu ◽  
Donna M. Van Winkle
Keyword(s):  
Myocardial Ischemia ◽  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Opioid Peptide ◽  
Area At Risk ◽  
Regional Myocardial Ischemia ◽  
Chronic Infusion ◽  
Myocardial Ischemia Reperfusion

Recently, we reported that exogenous administration of Met5-enkephalin (ME) for 24 h reduces infarct size after ischemia-reperfusion in rabbits. In the present study, we tested whether ME-induced cardioprotection is exhibited in murine hearts and whether chronic infusion of this peptide can render hearts tolerant to ischemia. Barbiturate-anesthetized open-chest mice (C57BL/6J) were subjected to regional myocardial ischemia-reperfusion (45 min of occlusion and 20 min of reperfusion). Mice received saline vehicle or ME for 24 h or 2 wk before undergoing regional myocardial ischemia-reperfusion or for 24 h followed by a 24-h delay before regional myocardial ischemia-reperfusion. Infarct size was measured with propidium iodide and is expressed as a percentage of the area at risk. Infarcts were smaller after infusion of ME for 24 h than with vehicle control: 49.2 ± 9.0% vs. 22.2 ± 3.2% ( P < 0.01). In contrast, administration of ME for 2 wk failed to elicit cardioprotection: 36.5 ± 9.1% and 41.4 ± 8.2% for control and ME, respectively ( P = not significant). When a 24-h delay was imposed between the end of drug treatment and the onset of the ischemic insult, cardioprotection was lost: 38.5 ± 6.1% and 42.8 ± 6.6% for control and ME, respectively ( P = not significant). Chronic sustained exogenous infusion of the endogenously produced opioid peptide ME is associated with loss of the cardioprotection that is observed with 24 h of infusion. Furthermore, in this in vivo murine model, ME failed to induce delayed tolerance to myocardial ischemia-reperfusion.

Coronary endothelial P-selectin in pathogenesis of myocardial ischemia-reperfusion injury

1998 ◽  
Vol 275 (5) ◽  
pp. H1865-H1872 ◽  
Author(s):  
Anthony J. Palazzo ◽  
Steven P. Jones ◽  
Donald C. Anderson ◽  
D. Neil Granger ◽  
David J. Lefer
Keyword(s):  
Myocardial Ischemia ◽  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Myocardial Infarct Size ◽  
Wild Type ◽  
Area At Risk ◽  
Myocardial Ischemia Reperfusion

We investigated in vivo coronary P-selectin expression and its pathophysiological consequences in a murine model of myocardial ischemia-reperfusion (MI/R) using wild-type and P-selectin deficient (−/−) mice. Coronary P-selectin expression [μg monoclonal antibody (MAb)/g tissue] was measured using a radiolabeled MAb method after 30 min of myocardial ischemia and 20 min of reperfusion. P-selectin expression in wild-type mice was significantly ( P< 0.01) elevated in the ischemic zone (0.070 ± 0.010) compared with the nonischemic zone (0.037 ± 0.008). Myocardial P-selectin expression was nearly undetectable in P-selectin −/− mice after MI/R. Furthermore, myocardial infarct size (% of area at risk) after 30 min of myocardial ischemia and 120 min of reperfusion was 42.5 ± 4.4 in wild-type mice and 24.4 ± 4.0 in P-selectin −/− mice ( P < 0.05). In additional experiments of prolonged myocardial ischemia (60 min) and reperfusion (120 min), myocardial infarct size was similar in P-selectin −/− mice and wild-type mice. Our results clearly demonstrate the involvement of coronary P-selectin in the development of myocardial infarction after MI/R.

Abstract 843: Cardiomyocyte Overexpression of the Hydrogen Sulfide Producing Enzyme Cystathioine gamma-Lyase Attenuates Myocardial Ischemia-Reperfusion Injury

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
John W Elrod ◽  
John W Calvert ◽  
Chi-Wing Chow ◽  
Joanna Morrison ◽  
Jeannette E Doeller ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Fold Increase ◽  
Area At Risk ◽  
Physiological Processes ◽  
Myocardial Ischemia Reperfusion Injury ◽  
Myocardial Ischemia Reperfusion

Background : Hydrogen sulfide (H 2 S) was recently discovered to be an endogenously produced gaseous second messenger capable of modulating many physiological processes. We have previously demonstrated that administration of a H 2 S donor limits the extent of myocardial infarction. This prompted us to investigate the potential of endogenously generated H 2 S in acute cardioprotection utilizing mice with transgenic overexpression of an H 2 S producing enzyme. Methods: Mice with cardiac-specific overexpression of murine cystathionine γ-lyase (αMHC-CGL-Tg) were generated and analyzed for increased enzyme expression and H 2 S production utilizing a H 2 S specific polarographic electrode. αMHC-CGL-Tg and WT mice were then subjected to 45 min of in vivo LCA ischemia and 72 hr reperfusion and infarct size was evaluated using TTC staining. Results: αMHC-CGL-Tg mice displayed an increased level of myocardial CGL RNA, which translated into a (15 fold) increase in protein expression. This increase in CGL enzyme resulted in a significant (2 fold) increase in H 2 S production by myocardial homogenates of αMHC-CGL-Tg mice. αMHC-CGL-Tg mice were found to have a 47% reduction in infarct size per area-at-risk (INF/AAR) as compared to WT littermates. AAR was similar between both groups. Conclusions: This is the first evidence that overexpression of a H 2 S producing enzyme can decrease infarct size following MI-R injury. These findings demonstrate that modulation of endogenous H 2 S production may be of clinical benefit in ischemic disorders and that H 2 S generating enzymes may be viable therapeutic targets.

scholarly journals A Meta-Analysis of Resveratrol Protects against Myocardial Ischemia/Reperfusion Injury: Evidence from Small Animal Studies and Insight into Molecular Mechanisms

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Zhi-Jie Mao ◽  
Hui Lin ◽  
Jian-Wen Hou ◽  
Qian Zhou ◽  
Qian Wang ◽  
...  
Keyword(s):  
Myocardial Ischemia ◽  
Infarct Size ◽  
Animal Studies ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
Meta Analysis ◽  
Small Animal ◽  
Route Of Administration ◽  
Myocardial Ischemia Reperfusion

Aims. Myocardial ischemia/reperfusion (I/R) injury is a leading cause of cardiomyocyte loss and subsequent ventricular dysfunction after restoring the coronary blood flow and contributes to considerable increase in morbidity and mortality. Resveratrol has been declared to confer cardioprotection against in vivo and ex vivo myocardial I/R injury. Here, we have sought to investigate the effects of preconditioning with resveratrol on myocardial I/R damage across the small animal studies. Methods and Results. The MEDLINE, Google Scholar, PubMed, and Cochrane databases were searched for preclinical studies investigating resveratrol vs. vehicle published from the inception to July 2018. Eventually, 10 in vivo and 7 ex vivo studies with 261 animals (130 for resveratrol; 131 for vehicle) were included for meta-analysis. Pooled estimates for primary outcomes demonstrated that pretreatment with resveratrol significantly reduced the infarct size after myocardial I/R injury irrespective of in vivo (weighted mean difference (WMD): -13.42, 95% CI: -16.63 to -10.21, P≤0.001) or ex vivo (WMD: -15.05, 95% CI: -18.23 to -11.86, P≤0.001) studies. Consistently, stratified analysis according to the reperfusion duration, route of administration, or timing regimen of pretreatment all showed the infarct-sparing benefit of resveratrol. Metaregression did not indicate any difference in infarct size based on species, sample size, state, route of administration, reperfusion duration, and timing regimen of pretreatment. Meanwhile, sensitivity analysis also identified the cardioprotection of resveratrol with robust results in spite of significant heterogeneity. Conclusions. Preconditioning with resveratrol appears to prevent the heart from I/R injury in comparison with vehicle, as evidenced by limited infarct size in a preclinical setting. Studies with large animals or randomized controlled trials will add more evidence and provide the rationale for clinical use.

scholarly journals Metoprolol blunts the time-dependent progression of infarct size

2020 ◽  
Vol 115 (5) ◽  
Author(s):  
Manuel Lobo-Gonzalez ◽  
Carlos Galán-Arriola ◽  
Xavier Rossello ◽  
Maribel González‐Del‐Hoyo ◽  
Jean Paul Vilchez ◽  
...  
Keyword(s):  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Coronary Artery Occlusion ◽  
Primary Angioplasty ◽  
Primary Outcome Measure ◽  
Artery Occlusion ◽  
Area At Risk ◽  
Perfusion Computed Tomography ◽  
Myocardial Ischemia Reperfusion

Abstract Early metoprolol administration protects against myocardial ischemia–reperfusion injury, but its effect on infarct size progression (ischemic injury) is unknown. Eight groups of pigs (total n = 122) underwent coronary artery occlusion of varying duration (20, 25, 30, 35, 40, 45, 50, or 60 min) followed by reperfusion. In each group, pigs were randomized to i.v. metoprolol (0.75 mg/kg) or vehicle (saline) 20 min after ischemia onset. The primary outcome measure was infarct size (IS) on day7 cardiac magnetic resonance (CMR) normalized to area at risk (AAR, measured by perfusion computed tomography [CT] during ischemia). Metoprolol treatment reduced overall mortality (10% vs 26%, p = 0.03) and the incidence and number of primary ventricular fibrillations during infarct induction. In controls, IS after 20-min ischemia was ≈ 5% of the area AAR. Thereafter, IS progressed exponentially, occupying almost all the AAR after 35 min of ischemia. Metoprolol injection significantly reduced the slope of IS progression (p = 0.004 for final IS). Head-to-head comparison (metoprolol treated vs vehicle treated) showed statistically significant reductions in IS at 30, 35, 40, and 50-min reperfusion. At 60-min reperfusion, IS was 100% of AAR in both groups. Despite more prolonged ischemia, metoprolol-treated pigs reperfused at 50 min had smaller infarcts than control pigs undergoing ischemia for 40 or 45 min and similar-sized infarcts to those undergoing 35-min ischemia. Day-45 LVEF was higher in metoprolol-treated vs vehicle-treated pigs (41.6% vs 36.5%, p = 0.008). In summary, metoprolol administration early during ischemia attenuates IS progression and reduces the incidence of primary ventricular fibrillation. These data identify metoprolol as an intervention ideally suited to the treatment of STEMI patients identified early in the course of infarction and requiring long transport times before primary angioplasty.

scholarly journals Cardioprotective Effect of Novel Matrix Metalloproteinase Inhibitors

2020 ◽  
Vol 21 (19) ◽  
pp. 6990
Author(s):  
Kamilla Gömöri ◽  
Tamara Szabados ◽  
Éva Kenyeres ◽  
Judit Pipis ◽  
Imre Földesi ◽  
...  
Keyword(s):  
Matrix Metalloproteinase ◽  
Infarct Size ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Positive Control ◽  
Matrix Metalloproteinase 2 ◽  
Area At Risk ◽  
Triphenyltetrazolium Chloride

Background: We recently developed novel matrix metalloproteinase-2 (MMP-2) inhibitor small molecules for cardioprotection against ischemia/reperfusion injury and validated their efficacy in ischemia/reperfusion injury in cardiac myocytes. The aim of the present study was to test our lead compounds for cardioprotection in vivo in a rat model of acute myocardial infarction (AMI) in the presence or absence of hypercholesterolemia, one of the major comorbidities affecting cardioprotection. Methods: Normocholesterolemic adult male Wistar rats were subjected to 30 min of coronary occlusion followed by 120 min of reperfusion to induce AMI. MMP inhibitors (MMPI)-1154 and -1260 at 0.3, 1, and 3 µmol/kg, MMPI-1248 at 1, 3, and 10 µmol/kg were administered at the 25th min of ischemia intravenously. In separate groups, hypercholesterolemia was induced by a 12-week diet (2% cholesterol, 0.25% cholic acid), then the rats were subjected to the same AMI protocol and single doses of the MMPIs that showed the most efficacy in normocholesterolemic animals were tested in the hypercholesterolemic animals. Infarct size/area at risk was assessed at the end of reperfusion in all groups by standard Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC) staining, and myocardial microvascular obstruction (MVO) was determined by thioflavine-S staining. Results: MMPI-1154 at 1 µmol/kg, MMPI-1260 at 3 µmol/kg and ischemic preconditioning (IPC) as the positive control reduced infarct size significantly; however, this effect was not seen in hypercholesterolemic animals. MVO in hypercholesterolemic animals decreased by IPC only. Conclusions: This is the first demonstration that MMPI-1154 and MMPI-1260 showed a dose-dependent infarct size reduction in an in vivo rat AMI model; however, single doses that showed the most efficacy in normocholesterolemic animals were abolished by hypercholesterolemia. The further development of these promising cardioprotective MMPIs should be continued with different dose ranges in the study of hypercholesterolemia and other comorbidities.

scholarly journals Comparative Effects of Verapamil, Nicardipine, and Nitroglycerin on Myocardial Ischemia/Reperfusion Injury

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Hitoshi Yui ◽  
Uno Imaizumi ◽  
Hisashi Beppu ◽  
Mitsuhiro Ito ◽  
Munetaka Furuya ◽  
...  
Keyword(s):  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Rabbit Model ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Control Group ◽  
Area At Risk ◽  
Group A

The aim of this experiment was to establish whether verapamil, nicardipine, and nitroglycerin have (1) infarct size-limiting effects and (2) antiarrhythmic effects inin vivorabbit hearts during ischemia/reperfusion. Rabbits received regional ischemia by 30 min of left anterior descending coronary artery occlusion followed by 3 hours of reperfusion under ketamine and xylazine anesthesia. The animals were randomly assigned to the following 4 treatment groups: a control group, a verapamil group, a nicardipine group, and a nitroglycerin group. A continuous infusion of verapamil, nicardipine, or nitroglycerin was initiated 5 min prior to ischemia. Infarct size/area at risk decreased in verapamil, and nitroglycerin. The incidence of ischemia-induced arrhythmia decreased in nicardipine, verapamil and nitroglycerin. The incidence of reperfusion-induced arrhythmias decreased in verapamil and nitroglycerin. From the present experimental results, verapamil and nitroglycerin rather than nicardipine did afford significant protection to the heart subjected to ischemia and reperfusion in a rabbit model.

Adrenomedullin gene delivery attenuates myocardial infarction and apoptosis after ischemia and reperfusion

2003 ◽  
Vol 285 (4) ◽  
pp. H1506-H1514 ◽  
Author(s):  
Kazuo Kato ◽  
Hang Yin ◽  
Jun Agata ◽  
Hideaki Yoshida ◽  
Lee Chao ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Gene Transfer ◽  
Gene Delivery ◽  
Infarct Size ◽  
P38 Mapk ◽  
Ischemia Reperfusion ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Area At Risk ◽  
Calcitonin Gene ◽  
Myocardial Ischemia Reperfusion

Adrenomedullin (AM) has been shown to protect against cardiac remodeling. In this study, we investigated the potential role of AM in myocardial ischemia-reperfusion (I/R) injury through adenovirus-mediated gene delivery. One week after AM gene delivery, rats were subjected to 30-min coronary occlusion, followed by 2-h reperfusion. AM gene transfer significantly reduced the ratio of infarct size to ischemic area at risk and the occurrence of sustained ventricular fibrillation compared with control rats. AM gene delivery also attenuated apoptosis, assessed by both terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay and DNA laddering. The effect of AM gene transfer on infarct size, arrhythmia, and apoptosis was abolished by an AM antagonist, calcitonin gene-related peptide [CGRP(8–37)]. Expression of human AM significantly increased cardiac cGMP levels and reduced superoxide production, superoxide density, NAD(P)H oxidase activity, p38 MAPK activation, and Bax levels. Moreover, AM increased Akt and Bad phosphorylation and Bcl-2 levels, but decreased caspase-3 activation. These results indicate that AM protects against myocardial infarction, arrhythmia, and apoptosis in I/R injury via suppression of oxidative stress-induced Bax and p38 MAPK phosphorylation and activation of the Akt-Bad-Bcl-2 signaling pathway. Successful application of this technology may have a protective effect in coronary artery diseases.

Abstract 413: Engineering Targeted Growth Factors for Selective Pro-survival Signaling in Apoptotic Cardiomyocytes Following Ischemic Injury

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Timothy R Stowe ◽  
Laura D Jennings-Antipov ◽  
Kristopher M Kuchenbecker ◽  
Yan Zhang ◽  
Shawdee Eshghi ◽  
...  
Keyword(s):  
Growth Factors ◽  
Infarct Size ◽  
Heart Function ◽  
Ischemia Reperfusion ◽  
Smart Growth ◽  
Apoptotic Cells ◽  
Area At Risk ◽  
Reduce Infarct Size ◽  
Survival Signaling

Background: Despite the benefits of reperfusion therapy after myocardial infarction (MI), most patients still progress to heart failure. MI patients suffer irreversible loss of heart function due to cardiomyocyte (CM) death and tissue scarring. Growth factors (GFs) reduce scar size and limit CM apoptosis in preclinical studies, however native GFs have poor drug-like qualities and have not been successful in the clinic. Silver Creek Pharmaceuticals is developing a new class of targeted, growth factor-based therapeutics (Smart Growth Factors) that are engineered to have optimized pharmacokinetics, dynamics and safety profiles. Our first generation of SGFs use annexin-V (AnxV) to target IGF-1 to damaged CMs and selectively activate pro-survival signaling. Methods and Results: We used biophysical simulation to design an IGF-1-based SGF that selectively activated the PI3K pathway in damaged cells. SGFs were engineered to target IGF-1 to damaged cells through the binding of AnxV to phosphatidylserine exposed on the surface of apoptotic cells. These bispecific proteins were constructed with half-life modulators and linkers, then screened for their ability to selectively increase pAKT levels in apoptotic iPSC-derived human CMs. We identified a subset of SGFs that were able to selectively increase pAKT levels in apoptotic cells as compared to healthy cells (p<0.05). Based on these data, we tested the ability of SGFs to activate pro-survival signaling and reduce infarct size in a rat ischemia/reperfusion model of acute MI (AMI). SGFs were able to selectively prolong pAKT in the infarcted region of the left ventricle without activating signaling in remote healthy tissue out to 2 hours post-reperfusion (n=3-6/group, p<0.05). For efficacy studies, rats were subjected to 60 minutes of ischemia followed by 72 hours of reperfusion. A single IV dose of SGF (600 pmol/kg) administered at time of reperfusion was able to significantly reduce infarct size relative to the area-at-risk (infarct/AAR%) as compared to controls (p<0.05; SGF 12.7±5% n=10; wt IGF-1 20.3±3% n=8 and vehicle 27.6±7% n=12). Conclusions: This work demonstrates that SGFs selectively activate pro-survival signals in distressed CMs and lead to reduced infarct size in vivo without off-target effects.

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