KCNQ1 suppression-replacement gene therapy in transgenic rabbits with type 1 long QT syndrome.

BACKGROUND AND AIMS Type 1 long QT syndrome (LQT1) is caused by pathogenic variants in the KCNQ1-encoded Kv7.1 potassium channels, which pathologically prolong ventricular action potential duration (APD). Herein, the pathologic phenotype in transgenic LQT1 rabbits is rescued using a novel KCNQ1 suppression-replacement (SupRep) gene therapy. METHODS KCNQ1-SupRep gene therapy was developed by combining into a single construct a KCNQ1 shRNA (suppression) and an shRNA-immune KCNQ1 cDNA (replacement), packaged into adeno-associated virus serotype 9, and delivered in vivo via an intra-aortic root injection (1E10 vg/kg). To ascertain the efficacy of SupRep, 12-lead electrocardiograms were assessed in adult LQT1 and wild-type (WT) rabbits and patch-clamp experiments were performed on isolated ventricular cardiomyocytes. RESULTS KCNQ1-SupRep treatment of LQT1 rabbits resulted in significant shortening of the pathologically prolonged QT index (QTi) towards WT levels. Ventricular cardiomyocytes isolated from treated LQT1 rabbits demonstrated pronounced shortening of APD compared to LQT1 controls, leading to levels similar to WT (LQT1-UT vs. LQT1-SupRep, P < .0001, LQT1-SupRep vs. WT, P = ns). Under β-adrenergic stimulation with isoproterenol, SupRep-treated rabbits demonstrated a WT-like physiological QTi and APD90 behaviour. CONCLUSIONS This study provides the first animal-model, proof-of-concept gene therapy for correction of LQT1. In LQT1 rabbits, treatment with KCNQ1-SupRep gene therapy normalized the clinical QTi and cellular APD90 to near WT levels both at baseline and after isoproterenol. If similar QT/APD correction can be achieved with intravenous administration of KCNQ1-SupRep gene therapy in LQT1 rabbits, these encouraging data should compel continued development of this gene therapy for patients with LQT1

Endothelialization of sirolimus-eluting stents with slow and extended drug release in the porcine overstretch model

BACKGROUND: Vascular healing of intracoronary stents has been shown to be delayed in drug-eluting stents (DES) due to the cytotoxic compounds on the stent surface that prevent stent ingrowth and endothelialization. The lack of endothelialization explains the occurrence of late and very late stent thrombosis in DES. MATERIALS AND METHODS: In 11 house swines (body weight 38-45 kg), 3 stents were implanted randomly into the 3 large epicardial coronary arteries, namely a bare-metal stent (BMS), a sirolimus-eluting stent with slow-release (SES) and a SES with extended-release (SESXR). Stent length was 18 mm, and stent diameter 3 mm. All stents were of identical design. Animals were followed for 3 (n = 3), 7 (n = 4) and 14 (n = 4) days, respectively. One animal died before implantation due to hyperthermia. On the day of explantation, the animals were euthanized and endothelialization was tested by scanning electron microscopy after drying and sputtering the samples. Endothelial coverage was determined semiquantitatively by 2 observers. RESULTS: Endothelialization was more rapid with BMS and SESXR than SES at 3 and 14 days. At 7 days there were no significant differences between the 2 SES. CONCLUSIONS: Endothelialization of intracoronary stents is faster with BMS and SESXR at 3 days than with SES. These differences persist at 14 days, suggesting delayed vascular healing with the slow-release SES

Anaesthetic and Perioperative Management of 14 Male New Zealand White Rabbits for Calvarial Bone Surgery.

Calvarial bone surgery on rabbits is frequently performed. This report aims to document a simple and practical anaesthetic and perioperative management for this procedure. Fourteen male New Zealand white rabbits were included in the study. Subcutaneous (SC) dexmedetomidine, ketamine and buprenorphine ± isoflurane vaporized in oxygen administered through a supraglottic airway device (V-gel®) provided clinically suitable anaesthesia. Supplemental oxygen was administered throughout recovery. Monitoring was clinical and instrumental (pulse-oximetry, capnography, invasive blood pressure, temperature, arterial blood gas analysis). Lidocaine was infiltrated at the surgical site and meloxicam was injected subcutaneously as perioperative analgesia. After surgery, pain was assessed five times daily (composite behavioural pain scale and grimace scale). Postoperative analgesia included SC meloxicam once daily for four days and buprenorphine every 8 h for three days (unless both pain scores were at the lowest possible levels). Rescue analgesia (buprenorphine) was administered in case of the score > 3/8 in the composite pain scale, >4/10 on the grimace scale or if determined necessary by the caregivers. Airway management with a V-gel® was possible but resulted in respiratory obstruction during the surgery in two cases. Hypoventilation was observed in all rabbits. All rabbits experienced pain after the procedure. Monitoring, pain assessments and administration of postoperative analgesia were recommended for 48 h