Search

Gene therapy has great potential for human diseases. Development of efficient delivery systems is critical to its clinical translation. Recent studies have shown that microbubbles in combination with ultrasound (US) can be used to facilitate gene delivery. An aim of this study is to investigate whether the combination of US-targeted microbubble destruction (UTMD) and polyethylenimine (PEI) (UTMD/PEI) can mediate even greater gene transfection efficiency than UTMD alone and to optimize ultrasonic irradiation parameters. Another aim of this study is to investigate the biological effects of PHD2-shRNA after its transfection into H9C2 cells. pEGFP-N1 or eukaryotic shPHD2-EGFP plasmid was mixed with albumin-coated microbubbles and PEI to form complexes for transfection. After these were added into H9C2 cells, the cells were exposed to US with various sets of parameters. The cells were then harvested and analyzed for gene expression. UTMD/PEI was shown to be highly efficient in gene transfection. An US intensity of 1.5 W/cm2, a microbubble concentration of 300μl/ml, an exposure time of 45s, and a plasmid concentration of 15μg/ml were found to be optimal for transfection. UTMD/PEI-mediated PHD2-shRNA transfection in H9C2 cells significantly down regulated the expression of PHD2 and increased expression of HIF-1α and downstream angiogenesis factors VEGF, TGF-β and bFGF. UTMD/PEI, combined with albumin-coated microbubbles, warrants further investigation for therapeutic gene delivery. [ABSTRACT FROM AUTHOR]

Acute cardiac allograft rejection (ACAR) is one of the main reasons for mortality after heart transplantation. The timely diagnosis of treatment‐needed ACAR is of great importance in the clinic. Molecular imaging may make accurate diagnoses at the early stage to visualize the activity of specific pathological processes. The amount of CD4+‐lymphocyte infiltration is a crucial index in ACAR grading. CD4‐targeted nanobubbles (NBCD4) are fabricated to assess the infiltrating CD4+ lymphocytes, while isotype control nanobubbles (NBIso) are also fabricated. Animal models with ACAR grades from 0R to 3R are established. Ultrasound molecular imaging (USMI) is performed to distinguish different rejection grades with NBCD4. In the grade 2R and 3R groups, the USMI signals of NBCD4 are significantly higher than those of NBIso. The signals of NBCD4 in the 2R group are significantly lower than those in the 3R group and significantly higher than those in the 1R and 0R groups. Moreover, the signals of NBCD4 are strongly correlated with the rejection grades and the number of infiltrating CD4+ lymphocytes. As asymptomatic rejection with 2R or higher grades should be seriously treated, USMI with NBCD4 may be a new approach to timely diagnosis of treatment‐needed ACAR. [ABSTRACT FROM AUTHOR]