A Bioengineered Hydrogel System Enables Targeted and Sustained Intramyocardial Delivery of Neuregulin, Activating the Cardiomyocyte Cell Cycle and Enhancing Ventricular Function in a Murine Model of Ischemic Cardiomyopathy

Abstract

Background Neuregulin (NRG) is a member of the epidermal growth factor family possessing a critical role in cardiomyocyte development and proliferation. Systemic administration of NRG demonstrated efficacy in cardiomyopathy animal models, leading to clinical trials employing daily NRG infusions. This approach is hindered by requiring daily infusions and off-target exposure. Therefore, this study aimed to encapsulate NRG in a hydrogel (HG) to be directly delivered to the myocardium, accomplishing sustained localized NRG delivery. Methods and Results NRG was encapsulated in HG and release over 14 days confirmed by ELISA in vitro. Sprague-Dawly rats were utilized for cardiomyocyte isolation. Cells were stimulated by PBS, NRG, HG, or NRG-HG and evaluated for proliferation. Cardiomyocytes demonstrated EdU and phosphorylated histone-H3 (PH3) positivity in the NRG-HG group only. For in vivo studies, 2 month old mice (n=60) underwent LAD ligation and were randomized to the 4 treatment groups mentioned. Only NRG-HG treated mice demonstrated PH3 and Ki67 positivity along with decreased caspase-3 activity compared to all controls. NRG was detected in myocardium 6 days following injection without evidence of off-target exposure in NRG-HG animals. At 2 weeks, the NRG-HG group exhibited enhanced LVEF, decreased LV area, and augmented borderzone thickness. Conclusions Targeted and sustained delivery of NRG directly to the myocardial borderzone augments cardiomyocyte mitotic activity, decreases apoptosis, and greatly enhances LV function in a model of ICM. This novel approach to NRG administration avoids off-target exposure and represents a clinically translatable strategy in myocardial regenerative therapeutics.

Neuregulin stimulation of cardiomyocyte regeneration in mice and human myocardium reveals a therapeutic window

“…Administration of rNRG1 stimulates cardiomyocyte cycling and proliferation in vitro and myocardial repair in vivo (22, 28–30). We used rNRG1 to investigate the effect of stimulating cardiomyocyte cycling.…”

“…We (22) and others (28–30) have previously demonstrated that rNRG1 stimulates cardiomyocyte proliferation. Thus, administration of rNRG1 stimulates a cellular mechanism that may show a large benefit in pediatric patients.…”

Regulating Stem Cell Secretome Using Injectable Hydrogels with In Situ Network Formation

“…For in vivo delivery of SHIELD, male adult Wistar rats (Charles River Laboratories) were anesthetized with isoflurane and a left fourth interspace thoracotomy was performed. [25] Fifty μL of SHIELD conjugated with a Cyanine5.5 near-infrared dye (Lumiprobe) was epicardially injected into the anterolateral wall of the left ventricle. SHIELD retention was quantified at 16 days post-injection from explanted hearts (n = 3 per treatment group).…”

Striated muscle function, regeneration, and repair

“…In these studies, biomaterial injections in peri-infarct zone mainly served to reduce the compliance mismatch between the scar and remote myocardium and consequently promote cell survival and favorable remodeling of the heart. Additionally, numerous studies have demonstrated further therapeutic benefits by incorporation of growth factors (bFGF, TGF-β1, IGF-1, VEGF, Neuregulin-1β) and/or cells in the injected biomaterials [183–185]. Many of such studies continue to be performed in small animals, however, studies in larger animal models [186] are required to develop effective treatment strategies with prospect for clinical translation.…”