Cardiac gene delivery using ultrasound: State of the field.

Over the past two decades, there has been tremendous and exciting progress toward extending the use of medical ultrasound beyond a traditional imaging tool. Ultrasound contrast agents, typically used for improved visualization of blood flow, have been explored as novel non-viral gene delivery vectors for cardiovascular therapy. Given this adaptation to ultrasound contrast-enhancing agents, this presents as an image-guided and site-specific gene delivery technique with potential for multi-gene and repeatable delivery protocols-overcoming some of the limitations of alternative gene therapy approaches. In this review, we provide an overview of the studies to date that employ this technique toward cardiac gene therapy using cardiovascular disease animal models and summarize their key findings.

Stable Cavitation-Mediated Delivery of miR-126 to Endothelial Cells.

In endothelial cells, microRNA-126 (miR-126) promotes angiogenesis, and modulating the intracellular levels of this gene could suggest a method to treat cardiovascular diseases such as ischemia. Novel ultrasound-stimulated microbubbles offer a means to deliver therapeutic payloads to target cells and sites of disease. The purpose of this study was to investigate the feasibility of gene delivery by stimulating miR-126-decorated microbubbles using gentle acoustic conditions (stable cavitation). A cationic DSTAP microbubble was formulated and characterized to carry 6 µg of a miR-126 payload per 109 microbubbles. Human umbilical vein endothelial cells (HUVECs) were treated at 20−40% duty cycle with miR-126-conjugated microbubbles in a custom ultrasound setup coupled with a passive cavitation detection system. Transfection efficiency was assessed by RT-qPCR, Western blotting, and endothelial tube formation assay, while HUVEC viability was monitored by MTT assay. With increasing duty cycle, the trend observed was an increase in intracellular miR-126 levels, up to a 2.3-fold increase, as well as a decrease in SPRED1 (by 33%) and PIK3R2 (by 46%) expression, two salient miR-126 targets. Under these ultrasound parameters, HUVECs maintained >95% viability after 96 h. The present work describes the delivery of a proangiogenic miR-126 using an ultrasound-responsive cationic microbubble with potential to stimulate therapeutic angiogenesis while minimizing endothelial damage.

An Overview of Cell Membrane Perforation and Resealing Mechanisms for Localized Drug Delivery.

Localized and reversible plasma membrane disruption is a promising technique employed for the targeted deposition of exogenous therapeutic compounds for the treatment of disease. Indeed, the plasma membrane represents a significant barrier to successful delivery, and various physical methods using light, sound, and electrical energy have been developed to generate cell membrane perforations to circumvent this issue. To restore homeostasis and preserve viability, localized cellular repair mechanisms are subsequently triggered to initiate a rapid restoration of plasma membrane integrity. Here, we summarize the known emergency membrane repair responses, detailing the salient membrane sealing proteins as well as the underlying cytoskeletal remodeling that follows the physical induction of a localized plasma membrane pore, and we present an overview of potential modulation strategies that may improve targeted drug delivery approaches.

Modeling Neoplastic Growth in Renal Cell Carcinoma and Polycystic Kidney Disease.

Renal cell carcinoma (RCC) and autosomal dominant polycystic kidney disease (ADPKD) share several characteristics, including neoplastic cell growth, kidney cysts, and limited therapeutics. As well, both exhibit impaired vasculature and compensatory VEGF activation of angiogenesis. The PI3K/AKT/mTOR and Ras/Raf/ERK pathways play important roles in regulating cystic and tumor cell proliferation and growth. Both RCC and ADPKD result in hypoxia, where HIF-α signaling is activated in response to oxygen deprivation. Primary cilia and altered cell metabolism may play a role in disease progression. Non-coding RNAs may regulate RCC carcinogenesis and ADPKD through their varied effects. Drosophila exhibits remarkable conservation of the pathways involved in RCC and ADPKD. Here, we review the progress towards understanding disease mechanisms, partially overlapping cellular and molecular dysfunctions in RCC and ADPKD and reflect on the potential for the agile Drosophila genetic model to accelerate discovery science, address unresolved mechanistic aspects of these diseases, and perform rapid pharmacological screens.

Multimodal prehabilitation before major abdominal surgery: A retrospective study.

INTRODUCTION: Prehabilitation may benefit older patients undergoing major surgeries. Currently, its efficacy has not been conclusively proven. This is a retrospective review of a multimodal prehabilitation programme. METHODS: Patients aged 65 years and above undergoing major abdominal surgery between May 2015 and December 2019 in the National University Hospital were included in our institutional programme that incorporated aspects of multimodal prehabilitation and Enhanced Recovery After Surgery concepts as 1 holistic perioperative pathway to deal with issues specific to older patients. Physical therapy, nutritional advice and psychosocial support were provided as part of prehabilitation. RESULTS: There were 335 patients in the prehabilitation cohort and 256 patients whose records were reviewed as control. No difference in postoperative length of stay (P=0.150) or major complications (P=0.690) were noted. Patients in the prehabilitation group were observed to ambulate a longer distance and participate more actively with their physiotherapists from postoperative day 1 until 4. In the subgroup of patients with cancer, more patients had undergone neoadjuvant therapy in the prehabilitation group compared to the control group (21.7% versus 12.6%, P=0.009). Prehabilitation patients were more likely to proceed to adjuvant chemotherapy (prehabilitation 87.2% vs control 65.6%, P<0.001) if it had been recommended. CONCLUSION: The current study found no differences in traditional surgical outcome measures with and without prehabilitation. An increase in patient mobility in the immediate postoperative period was noted with prehabilitation, as well as an association between prehabilitation and increased adherence to postoperative adjuvant therapy. Larger prospective studies will be needed to validate the findings of this retrospective review.