Delivery of CD151 by Ultrasound Microbubbles in Rabbit Myocardial Infarction

Inducing cavitation within hollow cylindrical radially polarized transducers for intravascular applications

Thrombotic occlusions of large blood vessels are increasingly treated with catheter based mechanical approaches, one of the most prominent being to employ aspiration to extract clots through a hollow catheter lumen. A central technical challenge for aspiration catheters is to achieve sufficient suction force to overcome the resistance of clot material entering into the distal tip. In this study, we examine the feasibility of inducing cavitation within hollow cylindrical transducers with a view to ultimately using them to degrade the mechanical integrity of thrombus within the tip of an aspiration catheter. Hollow cylindrical radially polarized PZT transducers with 3.3/2.5 mm outer/inner diameters were assessed. Finite element simulations and hydrophone experiments were used to investigate the pressure field distribution as a function of element length and resonant mode (thickness, length). Operating in thickness mode (∼5 MHz) was found to be associated with the highest internal pressures, estimated to exceed 23 MPa. Cavitation was demonstrated to be achievable within the transducer under degassed water (10 %) conditions using hydrophone detection and high-frequency ultrasound imaging (40 MHz). Cavitation clouds occupied a substantial portion of the transducer lumen, in a manner that was dependent on the pulsing scheme employed (10 and 100 μs pulse lengths; 1.1, 11, and 110 ms pulse intervals). Collectively the results support the feasibility of achieving cavitation within a transducer compatible with mounting in the tip of an aspiration format catheter.

CD151 Alleviates Early Blood-Brain Barrier Dysfunction After Experimental Focal Brain Ischemia in Rats

Preservation of the blood-brain barrier (BBB) function is a potential protective strategy against cerebral ischemic injuries. CD151 has a beneficial effect in maintaining vascular stability and plays a role in pro-angiogenesis. Both vascular stability and angiogenesis can affect BBB function. Therefore, we aimed to examine the action of CD151 in regulating BBB permeability after cerebral ischemic injury in the present study. Using a transient focal cerebral ischemia (tFCI) rat model, we established that CD151 overexpression in the brain mitigated the leakage of endogenous IgG at 6-24 h after tFCI in vivo. Moreover, we found that CD151 can decrease the diffusion of macromolecules through monolayer brain microvessel endothelial cells (BMVECs) after glucose and oxygen deprivation (OGD)-reoxygenation in vitro. Furthermore, overexpression of CD151 in BMVECs suppressed OGD-reoxygenation-induced F-actin formation and RhoA activity. However, while preserving BBB integrity after tFCI, CD151 overexpression did not affect the post-stroke outcomes. Taken together, the present study demonstrated that CD151 overexpression in the brain protects BBB permeability at early phase after tFCI. CD151 may be a potential target for early BBB protection in ischemic stroke.

The present and future role of ultrasound targeted microbubble destruction in preclinical studies of cardiac gene therapy

Multiple limitations for cardiac pharmacologic therapies like intolerance, individual variation in effectiveness, side effects, and high cost still remain, despite the recent progress in diagnosis and health support. Gene therapy is poised to be an attractive alternative in various ways for the future, refractory cardiac diseases being one aspect of it. As a novel therapy to deliver the objective gene to organs of living animals, ultrasound targeted microbubble destruction (UTMD) has therapeutic potential in cardiovascular disorders. UTMD, which binds microbubbles with DNA or RNA carriers into the shell and destroys the located microbubbles with low frequency and high mechanical index ultrasound can release target agents to specific organs. UTMD has the ability to transfect markedly through sonoporation, cavitation and other effects by way of intravenous injection that is minimally invasive and highly specific for gene deliverance. Here, we have summarized the present role of UTMD in pre-clinical studies of cardiac gene therapy which covers myocardial infarction, regeneration, ischaemia/reperfusion injury, hypertension, diabetic cardiomyopathy, adriamycin cardiomyopathy and some discussion for further studies.

MiR-124 aggravates failing hearts by suppressing CD151-facilitated angiogenesis in heart

Heart failure (HF) is the final common pathway of various cardiovascular diseases. Although it is well documented that reduction of cardiac angiogenesis contributes to the progression from adaptive cardiac hypertrophy to HF, the molecular mechanisms remain unknown. In the present study, we found that cardiac expression of miR-124 was increased in patients and mice with HF. Recombinant adeno-associated virus (rAAV)-mediated miR-124 over-expression aggravated angiotensin II (Ang II) infusion-induced cardiac dysfunction and abnormal cardiac angiogenesis in mice. In vitro, transfection of miR-124 mimics significantly promoted apoptosis and reduced viability, migration, tube formation, and nitric oxide release in endothelial cells. In addition, CD151 was identified as a direct target of miR-124. Endothelial cell injury caused by CD151 silencing was mimicked by miR-124 over-expression. Re-expression of CD151 attenuated miR-124-mediated suppression of cardiac angiogenesis and cardiac dysfunction in Ang II-treated mice. Our observations suggest that miR-124 is an important negative regulator of cardiac angiogenesis and cardiac function, likely by suppressing the expression of CD151 in heart cells. Modulation of miR-124 levels may provide new strategies and targets for HF therapy.