Ariel Wolf

Concise Review: Review and Perspective of Cell Dosage and Routes of Administration From Preclinical and Clinical Studies of Stem Cell Therapy for Heart Disease

An important stage in the development of any new therapeutic agent is establishment of the optimal dosage and route of administration. This can be particularly challenging when the treatment is a biologic agent that might exert its therapeutic effects via complex or poorly understood mechanisms. Multiple preclinical and clinical studies have shown paradoxical results, with inconsistent findings regarding the relationship between the cell dose and clinical benefit. Such phenomena can, at least in part, be attributed to variations in cell dosing or concentration and the route of administration (ROA). Although clinical trials of cell‐based therapy for cardiovascular disease began more than a decade ago, specification of the optimal dosage and ROA has not been established. The present review summarizes what has been learned regarding the optimal cell dosage and ROA from preclinical and clinical studies of stem cell therapy for heart disease and offers a perspective on future directions.

Growth Hormone–Releasing Hormone Agonists Reduce Myocardial Infarct Scar in Swine With Subacute Ischemic Cardiomyopathy

Background Growth hormone–releasing hormone agonists (GHRH‐As) stimulate cardiac repair following myocardial infarction (MI) in rats through the activation of the GHRH signaling pathway within the heart. We tested the hypothesis that the administration of GHRH‐As prevents ventricular remodeling in a swine subacute MI model. Methods and Results Twelve female Yorkshire swine (25 to 30 kg) underwent transient occlusion of the left anterior descending coronary artery (MI). Two weeks post MI, swine were randomized to receive injections of either 30 μg/kg GHRH‐A (MR‐409) (GHRH‐A group; n=6) or vehicle (placebo group; n=6). Cardiac magnetic resonance imaging and pressure–volume loops were obtained at multiple time points. Infarct, border, and remote (noninfarcted) zones were assessed for GHRH receptor by immunohistochemistry. Four weeks of GHRH‐A treatment resulted in reduced scar mass (GHRH‐A: −21.9±6.42%; P=0.02; placebo: 10.9±5.88%; P=0.25; 2‐way ANOVA; P=0.003), and scar size (percentage of left ventricular mass) (GHRH‐A: −38.38±4.63; P=0.0002; placebo: −14.56±6.92; P=0.16; 2‐way ANOVA; P=0.02). This was accompanied by improved diastolic strain. Unlike in rats, this reduced infarct size in swine was not accompanied by improved cardiac function as measured by serial hemodynamic pressure–volume analysis. GHRH receptors were abundant in cardiac tissue, with a greater density in the border zone of the GHRH‐A group compared with the placebo group. Conclusions Daily subcutaneous administration of GHRH‐A is feasible and safe in a large animal model of subacute ischemic cardiomyopathy. Furthermore, GHRH‐A therapy significantly reduced infarct size and improved diastolic strain, suggesting a local activation of the GHRH pathway leading to the reparative process.

Z-Plasty for Scar Contracture

Z-plasty is a versatile reconstructive technique used to improve the functional and aesthetic properties of scars. In addition to release wound contractures, Z-plasties are useful for primarily closing tissue defects. Z-plasties are based on tissue flaps that are marked preoperatively and raised intraoperatively to create a new central limb scar with relieved skin tension. Certain preoperative, intraoperative, and postoperative details, as described below, must be heeded to in order to prevent complications and successfully perform this procedure. Variations within this procedure exist in order to tailor to the specific needs of the reconstructive surgeon and the surrounding anatomy.