Ultrasound-Microbubble–Mediated Intercellular Adhesion Molecule-1 Small Interfering Ribonucleic Acid Transfection Attenuates Neointimal Formation After Arterial Injury in Mice

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.

Potentiation of anti-angiogenic eNOS-siRNA transfection by ultrasound-mediated microbubble destruction in ex vivo rat aortic rings

Nitric oxide (NO) regulates vascular homeostasis and plays a key role in revascularization and angiogenesis. The endothelial nitric oxide synthase (eNOS) enzyme catalyzes NO production in endothelial cells. Overexpression of the eNOS gene has been implicated in pathologies with dysfunctional angiogenic processes, such as cancer. Therefore, modulating eNOS gene expression using small interfering RNAs (siRNAs) represents a viable strategy for antitumor therapy. siRNAs are highly specific to the target gene, thus reducing off-target effects. Given the widespread distribution of endothelium and the crucial physiological role of eNOS, localized delivery of nucleic acid to the affected area is essential. Therefore, the development of an efficient eNOS-siRNA delivery carrier capable of controlled release is imperative for targeting specific vascular regions, particularly those associated with tumor vascular growth. Thus, this study aims to utilize ultrasound-mediated microbubble destruction (UMMD) technology with cationic microbubbles loaded with eNOS-siRNA to enhance transfection efficiency and improve siRNA delivery, thereby preventing sprouting angiogenesis. The efficiency of eNOS-siRNA transfection facilitated by UMMD was assessed using bEnd.3 cells. Synthesis of nitric oxide and eNOS protein expression were also evaluated. The silencing of eNOS gene in a model of angiogenesis was assayed using the rat aortic ring assay. The results showed that from 6 to 24 h, the transfection of fluorescent siRNA with UMMD was twice as high as that of lipofection. Moreover, transfection of eNOS-siRNA with UMMD enhanced the knockdown level (65.40 ± 4.50%) compared to lipofectamine (40 ± 1.70%). Silencing of eNOS gene with UMMD required less amount of eNOS-siRNA (42 ng) to decrease the level of eNOS protein expression (52.30 ± 0.08%) to the same extent as 79 ng of eNOS-siRNA using lipofectamine (56.30 ± 0.10%). NO production assisted by UMMD was reduced by 81% compared to 67% reduction transfecting with lipofectamine. This diminished NO production led to higher attenuation of aortic ring outgrowth. Three-fold reduction compared to lipofectamine transfection. In conclusion, we propose the combination of eNOS-siRNA and UMMD as an efficient, safe, non-viral nucleic acid transfection strategy for inhibition of tumor progression.

The Etiology and Molecular Mechanism Underlying Smooth Muscle Phenotype Switching in Intimal Hyperplasia of Vein Graft and the Regulatory Role of microRNAs

Mounting evidence suggests that the phenotypic transformation of venous smooth muscle cells (SMCs) from differentiated (contractile) to dedifferentiated (proliferative and migratory) phenotypes causes excessive proliferation and further migration to the intima leading to intimal hyperplasia, which represents one of the key pathophysiological mechanisms of vein graft restenosis. In recent years, numerous miRNAs have been identified as specific phenotypic regulators of vascular SMCs (VSMCs), which play a vital role in intimal hyperplasia in vein grafts. The review sought to provide a comprehensive overview of the etiology of intimal hyperplasia, factors affecting the phenotypic transformation of VSMCs in vein graft, and molecular mechanisms of miRNAs involved in SMCs phenotypic modulation in intimal hyperplasia of vein graft reported in recent years.

Ultrasound-Targeted Microbubble Destruction Enhances Inhibitory Effect of Apatinib on Angiogenesis in Triple Negative Breast Carcinoma Xenografts

Ultrasound-targeted microbubble destruction (UTMD) has been proven as an effective technique to assist drugs to cross the vascular wall and cell membrane. This study was aimed at evaluating the synergistic antiangiogenic and growth-inhibiting effects of apatinib (APA) and UTMD on the triple negative breast cancer (TNBC). The TNBC xenograft model was established in nude mice (n = 40) which were then randomly divided into the APA plus UTMD (APA-U) group, UTMD group, APA group, and model control (M) group (n = 10 per group). Corresponding treatment was done once daily for 14 consecutive days. The general condition and body weight of tumor-bearing nude mice were monitored. Routine blood test and detection of liver and kidney function were done after treatments. The tumor size and microcirculation were examined by two-dimensional ultrasonography (2DUS) and contrast-enhanced ultrasonography (CEUS), respectively. Then, the tumor tissues were harvested for the detection of vascular endothelial growth factor (VEGF) by immunohistochemistry and for CD31-PAS double staining to assess microvessel density (MVD) and heterogeneous vascular positivity rate. After treatments, the tumor growth and angiogenesis were significantly inhibited in the APA group and the APA-U group, and these effects were more obvious in the APA-U group. The tumor volume, CEUS parameters, VEGF expression, and MVD in the APA-U group were significantly lower than those in the APA group (P < 0.05), while there were no marked differences in the heterogeneous vascular positivity rate, body weight, and blood parameters between the two groups (P > 0.05). In the UTMD group, the tumor growth and angiogenesis were not significantly inhibited, and all the parameters were similar to those in the M group (P > 0.05). During the experiment, all mice survived and generally had good condition. In conclusion, APA combined with UTMD may exert synergistic antiangiogenic and growth-inhibiting effects on the TNBC and not increase the heterogeneous vasculature and the severity of APA-related systemic side effects.

Targeted galectin-7 inhibition with ultrasound microbubble targeted gene therapy as a sole therapy to prevent acute rejection following heart transplantation in a Rodent model

BACKGROUND

Despite significant advances in transplantation, acute cellular rejection (AR) remains a major obstacle that is most prevalent in the first months post heart transplantation (HT). Current treatments require high doses of immunosuppressive drugs followed by maintenance therapies that have systemic side effects including early infection. In this study, we attempted to prevent AR with a myocardial-targeted galectin-7-siRNA delivery method using cationic microbubbles (CMBs) combined with ultrasound targeted microbubble destruction (UTMD) to create local immunosuppression in a rat abdominal heterotopic heart transplantation acute rejection model.

METHODS AND RESULTS

Galectin-7-siRNA (siGal-7) bound to CMBs were synthesized and effective ultrasound-targeted delivery of siGal-7 into target cells confirmed in vitro. Based on these observations, three transplant rat models were tested：①isograft (ISO); ② Allograft (ALLO) +UTMD; and ③ALLO + PBS. UTMD treatments were administered at 1, 3, 5, 7 days after HT. Galectin 7 expression was reduced by 50% compared to ALLO + PBS (p < 0.005), and this was associated with significant reductions in both galectin 7 and Interleukin-2 protein levels (p < 0.001). The ALLO + UTMD group had Grade II or less inflammatory infiltration and myocyte damage in 11/12 rats using International Society For Heart and Lung Transplantation grading, compared to 0/12 rats with this grading in the ALLO + PBS group at 10 days post HT (p < 0.001).

CONCLUSIONS

Ultrasound-targeted galectin-7-siRNA knockdown with UTMD can prevent acute cellular rejection in the early period after allograft heart transplantation without the need for systemic immunosuppression.

KEY WORDS

Microbubble, Acute Rejection, Heart Transplantation, Galectin-7, RNA.

Effects of Cytotoxic T Lymphocyte-Associated Antigen 4 Immunoglobulin Combined with Microbubble-Mediated Irradiation on Hemodynamics of the Renal Artery in Rats with Diabetic Nephropathy

Cytotoxic T lymphocyte-associated antigen 4 immunoglobulin (CTLA-4-Ig) can inhibit the effect of B7-1 and improve renal hemodynamics in rats with diabetic nephropathy (DN). Nevertheless, a strategy that could increase the permeation of CTLA-4-Ig through endothelial cells and basement membrane remains to be discovered. We investigated the effect of CTLA-4-Ig combined with microbubble-mediated irradiation on the hemodynamics of renal arteries in DN rats. Rats were treated with CTLA-4-Ig and/or microbubble exposure. After 8 wk of intervention, color Doppler ultrasonography was used to detect peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (MV), systolic acceleration (SAC), pulsatility index (PI) and resistance index (RI) of the renal artery trunk. The CTLA-4-Ig + microbubble exposure group exhibited significantly higher PSV, EDV and MV than the CTLA-4-Ig group, which had significantly higher values than the non-intervention group. The CTLA-4-Ig + microbubble exposure group exhibited significantly lower SAC, PI and RI than the CTLA-4-Ig group, which had significantly lower values than the non-intervention group. Our results indicate that both CTLA-4-Ig and CTLA-4-Ig + microbubble exposure can reduce the blood flow resistance and improve the blood flow velocity of renal arteries in rats. Moreover, the effect of CTLA-4-Ig + microbubble exposure is better than that of CTLA-4-Ig alone. Our study provides a new, effective and non-invasive strategy for the treatment of DN.

Bioreducible, branched poly(β-amino ester)s mediate anti-inflammatory ICAM-1 siRNA delivery against myocardial ischemia reperfusion (IR) injury

ICAM-1 siRNA delivery mediated by bioreducible, branched BPAE-SS toward the anti-inflammatory treatment of myocardial IR injury.

Applications of Ultrasound to Stimulate Therapeutic Revascularization

Many pathological conditions are characterized or caused by the presence of an insufficient or aberrant local vasculature. Thus, therapeutic approaches aimed at modulating the caliber and/or density of the vasculature by controlling angiogenesis and arteriogenesis have been under development for many years. As our understanding of the underlying cellular and molecular mechanisms of these vascular growth processes continues to grow, so too do the available targets for therapeutic intervention. Nonetheless, the tools needed to implement such therapies have often had inherent weaknesses (i.e., invasiveness, expense, poor targeting, and control) that preclude successful outcomes. Approximately 20 years ago, the potential for using ultrasound as a new tool for therapeutically manipulating angiogenesis and arteriogenesis began to emerge. Indeed, the ability of ultrasound, especially when used in combination with contrast agent microbubbles, to mechanically manipulate the microvasculature has opened several doors for exploration. In turn, multiple studies on the influence of ultrasound-mediated bioeffects on vascular growth and the use of ultrasound for the targeted stimulation of blood vessel growth via drug and gene delivery have been performed and published over the years. In this review article, we first discuss the basic principles of therapeutic ultrasound for stimulating angiogenesis and arteriogenesis. We then follow this with a comprehensive cataloging of studies that have used ultrasound for stimulating revascularization to date. Finally, we offer a brief perspective on the future of such approaches, in the context of both further research development and possible clinical translation.

Antitumor activity of integrin αVβ3 antibody conjugated-cationic microbubbles in liver cancer

Background

The overexpression of integrin α_Vβ₃ in hepatocarcinoma (HCC) promotes tumor progression, metastasis, and clinical staging. Thus, the inhibition of integrin α_Vβ₃ might be potentially effective as an anti-cancer agent in HCC.

Methods

In this study, we aimed to investigate the antitumor effect of integrin α_Vβ₃ antibody conjugated cationic microbubbles (CMBs) in HCC model. By conjugating with integrin α_Vβ₃ antibody with non-targeting CMBs, CMBs_αvβ3 was constructed. The antitumor effect of CMBs_αvβ3 was evaluated in HepG2 cells in vitro and in HepG2 xenograft mice models. Bcl-2, p53 and CD31 mRNA level, and caspase-3 activity were examined in xenograft tumors. Cell proliferation assay and scratch test were performed to evaluate the anti-migrant effect of CMBs_αvβ3in vitro.

Results

CMBs_αvβ3 could specifically target to HCC HepG2 cells and improve pEGFP-KDRP-CD/TK plasmid transfection efficiency. In HepG2 xenograft mice models, CMBs_αvβ3 treatment significantly suppressed tumor weights and volumes. CMBs_αvβ3 treatment suppressed Bcl-2 and p53 mRNA level in tumors. In HepG2 cells, CMBs_αvβ3 significantly impaired wound healing and inhibited cell proliferation. Moreover, when combined with CD/TK double suicide gene transfection and 5-FC/GCV treatment, caspase-3 was activated and the cell proliferation was tremendously inhibited.

Conclusions

CMBs_αvβ3 not only suppresses cell migration and proliferation, but also facilitates 5-FC/GCV plus CD/TK double suicide gene-induced apoptotic cell death. CMBs_αvβ3 is a promising gene delivery agent with potential anti-tumor activity itself.

Cardiovascular Imaging and Theranostics in Cardiovascular Pharmacotherapy

Imaging plays a pivotal role in the diagnostic and prognostic assessment of cardiovascular diseases. During the past two decades, there has been an expansion of the available imaging techniques, some of which are now part of routine clinical practice. Cardiovascular imaging of atherosclerosis is a useful instrument, and it can corroborate and expand pathophysiological evidence on cardiovascular disease, providing proof of concept for medical therapy and can predict its responsiveness, and it may be able to be used as surrogate endpoints for clinical trials. Theranostics is an emerging therapy that combines imaging and therapeutic functions, using imaging-based therapeutic delivery systems. Theranostics could partially overcome current imaging limitations and translate experimental evidence and large-scale trials assessing clinical endpoints, rationalising cardiovascular drug development and paving the way to personalised medicine. The medical community cannot overlook the use of cardiovascular imaging as a complementary and supportive adjunct to trials investigating clinical endpoints, which remain the mainstay for investigating the efficacy and safety of cardiovascular pharmacotherapy.

Ultrasound-targeted microbubble destruction improved the antiangiogenic effect of Endostar in triple-negative breast carcinoma xenografts

PURPOSE

Ultrasound-targeted microbubble destruction (UTMD) has been reported to be a meritorious technique for drug targeting delivery. In this study, we aimed to evaluate the synergistic antiangiogenic effect of UTMD combined with Endostar on triple-negative breast carcinoma tumors.

MATERIALS AND METHODS

The lipid-shelled microbubbles (MBs) conjugated with Endostar were constructed using a biotin-avidin bridging chemistry method, and the morphological characteristics and drug-conjugating content were determined. MBs were administered intravenously to nude mice bearing MDA-MB-231 breast carcinoma xenografts and ultrasound exposure followed. The tumor microcirculation was observed by contrast-enhanced ultrasonography (CEUS) and the Endostar biodistribution was detected by enzyme-linked immunosorbent assay. Twenty-four breast carcinoma-bearing nude mice were divided into four groups. After treatment, every 3 days for 15 days the in vivo antitumor effects were assessed by calculating the tumor growth inhibition rate (TGIR). The tumor microcirculation was observed by CEUS, the tumor microvessel density (MVD) was calculated by immunohistochemistry under a microscope, and the vascular endothelial growth factor (VEGF) gene expression was detected by real-time quantitative polymerase chain reaction.

RESULTS

The prepared Endostar-conjugated MBs were round and well-dispersed with a mean size of 2.8 ± 0.7 µm and a drug conjugating content of 800.72 ± 70.53 µg/108 MBs. UTMD blocked the tumor microcirculation, and improved Endostar release in the targeted tumor tissue with a drug content of 1.12 ± 0.43 µg/gram protein, which was about three times higher than that in Endostar group or Endostar conjugated MBs group. Endostar-conjugated MBs combined with UTMD treatment achieved the optimal antitumor effects in vivo with a TGIR of 46.29%, and apparent antiangiogenic effects with minimal tumor blood perfusion, MVD and VEGF gene expression level.

CONCLUSION

UTMD can improve Endostar delivery in the targeting tumor tissue and mediate synergistic antiangiogenetic and antitumor effects, which may be a potential therapeutic strategy for refractory breast cancer.

Improving acute cardiac transplantation rejection therapy using ultrasound-targeted FK506-loaded microbubbles in rats

FK506-MBs combined with the UTMD technique increased drug concentrations in transplanted hearts and enhanced the therapeutic effect.

Ultrasound Technology for Molecular Imaging: From Contrast Agents to Multimodal Imaging

Ultrasound (US) takes advantage of ultrasound contrast agents (UCAs) to further increase the sensitivity and specificity of monitoring at the cellular level, which has had a considerable effect on the modern molecular imaging field. Gas-filled microbubbles (MBs) as UCAs in the bloodstream generate resonant volumetric oscillations in response to rapid variations in acoustic pressure, which are related to both the acoustic parameters of applied ultrasound and the physicochemical properties of the contrast agents. Nanoscale UCAs have been developed and have attracted much attention due to their utility in detecting extravascular lesions. Ultrasound molecular assessment is achieved by binding disease-specific ligands to the surface of UCAs, which have been designed to target tissue biomarkers in the area of interest, such as blood vessels, inflammation, or thrombosis. Additionally, the development of multimodal imaging technology is conducive for integration of the advantages of various imaging techniques to acquire additional diagnostic information. In this review paper, the present status and the critical issues for developing ultrasound contrast agents and multimodal imaging applications are described. Conventional MB UCAs are first introduced, including their research material, diagnostic applications, and intrinsic limitations. Then, recent progress in developing targeted UCAs and phase-inversion contrast agents for diagnostic purposes is discussed. Finally, we review the present status and the critical issues for developing ultrasound-based multimodal imaging applications and summarize the existing challenges and future prospects.

Ultrasound microbubble-mediated transfection of NF-κB decoy oligodeoxynucleotide into gingival tissues inhibits periodontitis in rats in vivo

Periodontitis is a chronic infectious disease for which the fundamental treatment is to reduce the load of subgingival pathogenic bacteria by debridement. However, previous investigators attempted to implement a nuclear factor kappa B (NF-κB) decoy oligodeoxynucleotide (ODN) as a suppressor of periodontitis progression. Although we recently reported the effectiveness of the ultrasound-microbubble method as a tool for transfecting the NF-κB decoy ODN into healthy rodent gingival tissue, this technique has not yet been applied to the pathological gingiva of periodontitis animal models. Therefore, the aim of this study was to investigate the effectiveness of the technique in transfecting the NF-κB decoy ODN into rats with ligature-induced periodontitis. Micro computed tomography (micro-CT) analysis demonstrated a significant reduction in alveolar bone loss following treatment with the NF-κB decoy ODN in the experimental group. RT-PCR showed that NF-κB decoy ODN treatment resulted in significantly reduced expression of inflammatory cytokine transcripts within rat gingival tissues. Thus, we established a transcutaneous transfection model of NF-κB decoy ODN treatment of periodontal tissues using the ultrasound-microbubble technique. Our findings suggest that the NF-κB decoy ODN could be used as a significant suppressor of gingival inflammation and periodontal disease progression.

A new approach to transfect NF-κB decoy oligodeoxynucleotides into the periodontal tissue using the ultrasound-microbubble method

The objective of this study is to investigate the effect of the ultrasound-microbubble technique in nuclear factor kappa B (NF-κB) decoy oligodeoxynucleotide (ODN) transfection in the gingival tissue in mice. The 6-FAM-labeled scrambled decoy ODN with microbubbles was applied to the periodontal tissue in 8-week-old male C57BL/6J mice by ultrasound radiation at low (LUM-Sc) and high (HUM-Sc) intensities to optimize the transfection condition of the ultrasound-microbubble method. Histological inspections were performed two hours after transfection to compare the expression with that in the sham-operated group without ultrasound radiation (A-Sc). Then, an NF-κB decoy was transfected into the periodontal tissue using the high-intensity ultrasound-microbubble (HUM-NF) technique to examine the anti-inflammatory effects of the decoy ODN. Western blot analysis was performed to investigate the expression of interleukin(IL)-1β, IL-6 and intercellular adhesion molecule-1 (ICAM-1) in the gingival tissues in the HUM-Sc, the HUM-NF and control groups. The fluorescence microscopy results showed that the fluorescent intensity in the periodontal tissues in the LUM-Sc and HUM-Sc groups was significantly higher than that in the A-Sc and the control groups. The fluorescent intensity in the HUM-Sc group, especially in the gingival connective tissue, was the highest of all groups. Western blot analysis indicated that the protein expression levels of IL-1β, IL-6 and ICAM-1 in the HUM-NF group were significantly lower than those in the HUM-Sc and the control groups. These findings suggest that the high-intensity ultrasound-microbubble technique is an effective tool for decoy transfection into the periodontal tissue.

Downregulation of Renal G Protein-Coupled Receptor Kinase Type 4 Expression via Ultrasound-Targeted Microbubble Destruction Lowers Blood Pressure in Spontaneously Hypertensive Rats

BACKGROUND

G protein-coupled receptor kinase type 4 (GRK4) plays a vital role in the long-term control of blood pressure (BP) and sodium excretion by regulating renal G protein-coupled receptor phosphorylation, including dopamine type 1 receptor (D1R). Ultrasound-targeted microbubble destruction (UTMD) is a promising method for gene delivery. Whether this method can deliver GRK4 small interfering RNA (siRNA) and lower BP is not known.

METHODS AND RESULTS

BP, 24-hour sodium excretion, and urine volume were measured after UTMD-targeted GRK4 siRNA delivery to the kidney in spontaneously hypertensive rats. The expression levels of GRK4 and D1R were determined by immunoblotting. The phosphorylation of D1R was investigated using immunoprecipitation. The present study revealed that UTMD-mediated renal GRK4 siRNA delivery efficiently reduced GRK4 expression and lowered BP in spontaneously hypertensive rats, accompanied by increased sodium excretion. The increased sodium excretion might be accounted for by the UTMD regulation of D1R phosphorylation and function in spontaneously hypertensive rats. Further analysis showed that, although UTMD had no effect on D1R expression, it reduced D1R phosphorylation in spontaneously hypertensive rats kidneys and consequently increased D1R-mediated natriuresis and diuresis.

CONCLUSIONS

Taken together, these study results indicate that UTMD-targeted GRK4 siRNA delivery to the kidney effectively reduces D1R phosphorylation by inhibiting renal GRK4 expression, improving D1R-mediated natriuresis and diuresis, and lowering BP, which may provide a promising novel strategy for gene therapy for hypertension.

Effects of Cationic Microbubble Carrying CD/TK Double Suicide Gene and αVβ3 Integrin Antibody in Human Hepatocellular Carcinoma HepG2 Cells

Objective

Hepatocellular carcinoma (HCC), mostly derived from hepatitis or cirrhosisis, is one of the most common types of liver cancer. T-cell mediated immune response elicited by CD/TK double suicide gene has shown a substantial antitumor effect in HCC. Integrin α_Vβ₃ over expresssion has been suggested to regulate the biology behavior of HCC. In this study, we investigated the strategy of incorporating CD/TK double suicide gene and anti-α_Vβ₃ integrin monoclonal antibodies into cationic microbubbles (CMBs_αvβ3), and evaluated its killing effect in HCC cells.

Methods

To improve the transfection efficiency of targeted CD/TK double suicide gene, we adopted cationic microbubbles (CMBs), a cationic delivery agent with enhanced DNA-carrying capacity. The ultrasound and high speed shearing method was used to prepare the non-targeting cationic microbubbles (CMBs). Using the biotin-avidin bridge method, α_Vβ₃ integrin antibody was conjugated to CMBs, and CMBs_αvβ3 was generated to specifically target to HepG2 cells. The morphology and physicochemical properties of the CMBs_αvβ3 was detected by optical microscope and zeta detector. The conjugation of plasmid and the antibody in CMBs_αvβ3 were examined by immunofluorescent microscopy and flow cytometry. The binding capacities of CMBs_αvβ3 and CMBs to HCC HepG2 and normal L-02 cells were compared using rosette formation assay. To detect EGFP fluorescence and examine the transfection efficiencies of CMBs_αvβ3 and CMBs in HCC cells, fluorescence microscope and contrast-enhanced sonography were adopted. mRNA and protein level of CD/TK gene were detected by RT-PCR and Western blot, respectively. To evaluate the anti-tumor effect of CMBs_αvβ3, HCC cells with CMBs_αvβ3 were exposed to 5-flurocytosine / ganciclovir (5-FC/GCV). Then, cell cycle distribution after treatment were detected by PI staining and flow cytometry. Apoptotic cells death were detected by optical microscope and assessed by MTT assay and TUNEL-staining assay.

Results

CMBs_αvβ3 had a regular shape and good dispersion. Compared to CMBs, CMBs_αvβ3 had more stable concentrations of α_Vβ₃ ligand and pEGFP-KDRP-CD/TK, and CMBs_αvβ3 was much sticker to HepG2 HCC cells than normal liver L-02cells. Moreover, after exposed to anti-α_Vβ₃ monoclonal antibody, the adhesion of CMBs_αvβ3 to HepG2 cells and L-02 cells were significantly reduced. Also, CMBs_αvβ3 demonstrated a substantially higher efficiency in pEGFP-KDRP-CD/TK plasmid transfection in HepG2 cells than CMBs. In addition, CMBs_αvβ3 could significantly facilitate 5-FC/GCV-induced cell cycle arrest in S phase. Moreover, treatment of 5-FC/GCV combined with CMBs_αvβ3 resulted in a marked apoptotic cell death in HepG2 and SK-Herp-1 HCC cells. In vitro, treatment of 5-FC/GCV combined with CMBs_αvβ3 suppresed cell proliferation. In nude mice model, 5-FU + GCV combined with plasmid + CMBs_αvβ3were able to significantly suppress tumor volumes.

Conclusion

Through biotin-avidin mediation system, CMBs_αvβ3 were successfully generated to specifically target HCC HepG2 cells. More importantly, CMBs_αvβ3 could significantly facilitate 5-FC/GCV-induced cell cycle arrest and apoptotic cell death in HepG2 cells. Our study demonstrated a potential strategy that could be translated clinically to improve liver tumor gene delivery.

Toll-like receptor 4 signaling has a critical role in Porphyromonas gingivalis-accelerated neointimal formation after arterial injury in mice

Recently, we reported that a periodontopathic pathogen, Porphyromonas gingivalis (P. gingivalis), infection induced neointimal hyperplasia with enhanced expression of monocyte chemoattractant protein (MCP)-1 after arterial injury in wild-type mice. Toll-like receptor (TLR) 4 is known to be a key receptor for virulence factors of P. gingivalis. The aim of this study is to assess the hypothesis that TLR4 has a critical role in periodontopathic bacteria-induced neointimal formation after an arterial injury. Wild-type and TLR4-deficient mice were used in this study. The femoral arteries were injured, and P. gingivalis or vehicle was injected subcutaneously once per week. Fourteen days after arterial injury, murine femoral arteries were obtained for histopathological and immunohistochemical analyses. The anti-P. gingivalis IgG levels in P. gingivalis-infected groups were significantly increased compared with the anti-P. gingivalis IgG levels of the corresponding non-infected groups in both wild-type and TLR4-deficient mice. TLR4 deficiency negated P. gingivalis-induced neointimal formation compared with that observed in wild-type mice and reduced the number of MCP-1 positive cells in the neointimal area. We conclude that P. gingivalis infection may promote neointimal formation after an arterial injury through TLR4 signaling.

Calreticulin Regulates Neointima Formation and Collagen Deposition following Carotid Artery Ligation

BACKGROUND/AIMS

The endoplasmic reticulum (ER) stress protein, calreticulin (CRT), is required for the production of TGF-β-stimulated extracellular matrix (ECM) by fibroblasts. Since TGF-β regulates vascular fibroproliferative responses and collagen deposition, we investigated the effects of CRT knockdown on vascular smooth-muscle cell (VSMC) fibroproliferative responses and collagen deposition.

METHODS

Using a carotid artery ligation model of vascular injury, Cre-recombinase-IRES-GFP plasmid was delivered with microbubbles (MB) to CRT-floxed mice using ultrasound (US) to specifically reduce CRT expression in the carotid artery.

RESULTS

In vitro, Cre-recombinase-mediated CRT knockdown in isolated, floxed VSMCs decreased the CRT transcript and protein, and attenuated the induction of collagen I protein in response to TGF-β. TGF-β stimulation of collagen I was partly blocked by the NFAT inhibitor 11R-VIVIT. Following carotid artery ligation, CRT staining was upregulated with enhanced expression in the neointima 14-21 days after injury. Furthermore, Cre-recombinase-IRES-GFP plasmid delivered by targeted US reduced CRT expression in the neointima of CRT-floxed mice and led to a significant reduction in neointima formation and collagen deposition. The neointimal cell number was also reduced in mice, with a local, tissue-specific knockdown of CRT.

CONCLUSIONS

This work establishes a novel role for CRT in mediating VSMC responses to injury through the regulation of collagen deposition and neointima formation.

Inhibitory effects of shRNA on expression of JNK1 and migration and invasion in mouse hepatocellular carcinoma cell lines mediated by ultrasound-targeted microbubble destruction

AIM

The inhibitory effects on expression of JNK1 in mouse hepatocellular carcinoma cell lines and cell migration and invasion were mediated by ultrasound-targeted microbubble destruction (UTMD).

MATERIALS AND METHODS

The best shRNA vector was built and screened. The hepatocellular carcinoma cell lines were cultured in vitro and divided into five groups: the group of normal Hca-F cells, the group of shRNA plasmid (already selected from the above procedure), the group of Lipofectamine, the group of UTMD (ultrasound microbubbles combined with ultrasound exposure) and the group of Lipofectamine and UTMD. The transfection rate was observed by inverted fluorescence microscope. The expression levels of JNK1 mRNA and protein were evaluated by fluorescence quantitative PCR and Western Blot respectively. The cell proliferation was detected by CCK-8. The ability of migration and invasion in vitro was detected by transwell assay.

RESULTS

The best shRNA vector was established. The comparison of the transfection rate: The group of Lipofectamine and UTMD was larger than that of the groups of shRNA plasmid, Lipofectamine lipofection and UTMD (all P<0.05). There was no significant difference between the group of Lipofectamine and the group of UTMD (P>0.05). The comparison of the expression levels of JNK1 mRNA and protein: Both of the mRNA and protein expression levels were lowest in the group of Lipofectamine and UTMD (all P<0.05). CCK-8 showed that cell viability decreased most in the group of Lipofectamine and UTMD (all P<0.05); Transwell assay showed that the abilities of migration and invasion decreased most in the group of Lipofectamine and UTMD (all P<0.05).

CONCLUSION

The transfection rate of JNK1 shRNA can be improved through the combination of lipofection and UTMD in mouse hepatocellular carcinoma cell lines, therefore enhancing the inhibitory effects of gene expression. The inhibitory effects of cell proliferation, migration and invasion can also be enhanced.

Therapeutic Angiogenesis by Ultrasound-Mediated MicroRNA-126-3p Delivery

OBJECTIVE

MicroRNAs are involved in many critical functions, including angiogenesis. Ultrasound-targeted microbubble destruction (UTMD) is a noninvasive technique for targeted vascular transfection of plasmid DNA and may be well suited for proangiogenic microRNA delivery. We aimed to investigate UTMD of miR-126-3p for therapeutic angiogenesis in chronic ischemia.

APPROACH AND RESULTS

The angiogenic potential of miR-126-3p was tested in human umbilical vein endothelial cells in vitro. UTMD of miR-126-3p was tested in vivo in Fischer-344 rats before and after chronic left femoral artery ligation, evaluating target knockdown, miR-126-3p and miR-126-5p expression, phosphorylated Tie2 levels, microvascular perfusion, and vessel density. In vitro, miR-126-3p-transfected human umbilical vein endothelial cells showed repression of sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2, negative regulators of vascular endothelial growth factor and angiopoietin-1 signaling, increased phosphorylated Tie2 mediated by knockdown of phosphatidylinositol-3-kinase regulatory subunit 2 and greater angiogenic potential mediated by both vascular endothelial growth factor/vascular endothelial growth factor R2 and angiopoietin-1 /Tie2 effects. UTMD of miR-126-3p resulted in targeted vascular transfection, peaking early after delivery and lasting for >3 days, and resulting in inhibition of sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2, with minimal uptake in remote organs. Finally, UTMD of miR-126-3p to chronic ischemic hindlimb muscle resulted in improved perfusion, vessel density, enhanced arteriolar formation, pericyte coverage, and phosphorylated Tie2 levels, without affecting miR-126-5p or delta-like 1 homolog levels.

CONCLUSIONS

UTMD of miR-126 results in improved tissue perfusion and vascular density in the setting of chronic ischemia by repressing sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2 and enhancing vascular endothelial growth factor and angiopoietin-1 signaling, with no effect on miR-126-5p. UTMD is a promising platform for microRNA delivery, with applications for therapeutic angiogenesis.

In Vivo Transfection and Detection of Gene Expression of Stem Cells Preloaded with DNA-carrying Microbubbles

PURPOSE

To determine whether (a) stem cells loaded with DNA-carrying microbubbles (MBs) can be transfected in vivo, (b) the cells remain alive to express the gene, and (c) gene expression is sufficiently robust to be detected in vivo.

MATERIALS AND METHODS

The study was approved by the Institutional Animal Care and Use Committee. Cationic MBs were prepared, characterized, and loaded with pLuciferase green fluorescent protein (GFP) plasmid. Loading was confirmed with SYBR Gold staining (Life Technologies, Carlsbad, Calif). C17.2 cells were loaded with the DNA-carrying MBs. Two hundred thousand cells suspended in 20 μL phosphate-buffered saline were mixed with 200 μL Matrigel (BD Biosciences, San Jose, Calif) and injected in both flanks of eight nude mice. One of the Matrigel (BD Biosciences) injections contained 50 000 cells pretransfected in vitro by using lipofectamine as a positive control. Nine flanks were exposed to 2.25-MHz ultrasonic pulses at 50% duty cycle for 1 minute at 1 W/cm(2) (n = 3) or 2 W/cm(2) (n = 6), and six flanks served as the negative control. Two days later, bioluminescent images were acquired in each mouse every 3 minutes for 1 hour after the intraperitoneal injection of d-luciferin (Perkin Elmer, Waltham, Mass). Differences between groups were assessed by using the nonparametric Kruskal-Wallis test with Wilcoxon rank sum tests for follow-up comparisons. Mice were then killed, plugs were explanted, and alternate sections were stained with hematoxylin-eosin or stained for GFP expression.

RESULTS

Mean DNA-loaded MB diameter ± standard deviation was 2.87 μm ± 1.69 with the DNA associated with the MB shell. C17.2 cells were associated with 2-4 MBs each, and more than 90% were viable. Peak background subtracted bioluminescent signal was fourfold higher when cells were exposed to 2 W/cm(2) pulses as compared with 1 W/cm(2) pulses (P = .02) and negative controls (P = .002). Histologic examination showed cells within the Matrigel (BD Biosciences) with robust GFP expression only after 2 W/cm(2) ultrasound exposure and lipofectamine transfection.

CONCLUSION

Stem cells loaded with DNA-carrying MBs can be transfected in vivo with ultrasonic pulses and remain alive to demonstrate robust gene expression.

Ultrasound and microbubble-induced local delivery of MicroRNA-based therapeutics

MicroRNAs are involved in many pathologic processes and are a promising target for therapeutic intervention. However, successful, localized delivery of microRNA-based therapeutics is lacking. In this study, cationic ultrasound-responsive microbubbles (MBs) were used to deliver microRNA blockers and mimics in vitro and in vivo. Cationic MBs successfully delivered microRNA blockers to human endothelial cells on ultrasound (US) exposure in vitro. This in vitro US protocol did not successfully deliver microRNA mimics to skeletal muscle of mice, whereas an US protocol that is routinely used for contrast imaging did. Additionally, we used cationic MBs and US to locally deliver antimiR and antagomiR molecules with US causing inertial cavitation. Delivery of antimiR to the extracellular compartments of the muscle was only slightly increased, whereas delivery of antagomiR to the capillaries, myocytes and extracellular space was significantly increased. AntagomiR seems to be a more suitable microRNA blocker than antimiR for use in combination with MBs and US for local delivery.

Cardiovascular drug delivery with ultrasound and microbubbles

Microbubbles lower the threshold for cavitation of ultrasound and have multiple potential therapeutic applications in the cardiovascular system. One of the first therapeutic applications to enter into clinical trials has been microbubble-enhanced sonothrombolysis. Trials were conducted in acute ischemic stroke and clinical trials are currently underway for sonothrombolysis in treatment of acute myocardial infarction. Microbubbles can be targeted to epitopes expressed on endothelial cells and thrombi by incorporating targeting ligands onto the surface of the microbubbles. Targeted microbubbles have applications as molecular imaging contrast agents and also for drug and gene delivery. A number of groups have shown that ultrasound with microbubbles can be used for gene delivery yielding robust gene expression in the target tissue. Work has progressed to primate studies showing delivery of therapeutic genes to generate islet cells in the pancreas to potentially cure diabetes. Microbubbles also hold potential as oxygen therapeutics and have shown promising results as a neuroprotectant in an ischemic stroke model. Regulatory considerations impact the successful clinical development of therapeutic applications of microbubbles with ultrasound. This paper briefly reviews the field and suggests avenues for further development.

Ultrasound and microbubble-targeted delivery of small interfering RNA into primary endothelial cells is more effective than delivery of plasmid DNA

Ultrasound and microbubble-targeted delivery (UMTD) is a promising non-viral technique for genetic-based therapy. We found that UMTD of small interfering RNA (siRNA) is more effective than delivery of plasmid DNA (pDNA). UMTD (1 MHz, 0.22 MPa) of fluorescently labeled siRNA resulted in 97.9 ± 1.5% transfected cells, with siRNA localized homogenously in the cytoplasm directly after ultrasound exposure. UMTD of fluorescently labeled pDNA resulted in only 43.0 ± 4.2% transfected cells, with localization mainly in vesicular structures, co-localizing with endocytosis markers clathrin and caveolin. Delivery of siRNA against GAPDH (glyceraldehyde-3-phosphate dehydrogenase) effectively decreased protein levels to 24.3 ± 7.9% of non-treated controls (p < 0.01). In contrast, 24 h after delivery of pDNA encoding GAPDH, no increase in protein levels was detected. Transfection efficiency, verified with red fluorescently labeled pDNA encoding enhanced green fluorescent protein, revealed that of the transfected cells, only 2.0 ± 0.7% expressed the transgene. In conclusion, the difference in localization between siRNA and pDNA after UMTD is an important determinant of the effectiveness of these genetic-based technologies.

Surfactant-free, lipo-polymersomes stabilized by iron oxide nanoparticles/polymer interlayer for synergistically targeted and magnetically guided gene delivery

Gene therapy holds promise to suppress carcinomas but still remains far removed from clinic because of the lack of a safe and effective delivery system. Besides enhancing transfection efficiency, the difficulty in gene therapy is how to deliver sufficient gene molecules to the site of interest. Herein, the rational design of surfactant-free lipo-polymersomes (LPPs) to overcome these problems is reported, simultaneously using a lipid-stabilized double emulsion approach. The LPPs are designed to conceal the cationic lipids and plasmid DNA inside the core along with iron oxide nanoparticles/polymer interlayer and a relatively neutral lipid shell to avoid the undesired interaction during circulation, leading to high accumulation in the tumors of mice. Furthermore, guided by an external magnetic field and the folic acid (FA) that target tumors via folate receptor-mediated endocytosis on the cell surface, the vectors demonstrate a 30-40-fold increase in cell uptake. Moreover, this synergistic tumor-targeted approach can enhance a 10-fold increase in in vivo transfection efficacy by promoting the delivery of LPPs to cancer cells and facilitating the endosomal escape of gene molecules. The new insights and capabilities represent a major step in nanovector engineering for safe and efficient gene delivery.

A novel cationic microbubble coated with stearic acid-modified polyethylenimine to enhance DNA loading and gene delivery by ultrasound

A novel cationic microbubble (MB) for improvement of the DNA loading capacity and the ultrasound-mediated gene delivery efficiency has been developed; it has been prepared with commercial lipids and a stearic acid modified polyethylenimine 600 (Stearic-PEI600) polymer synthesized via acylation reaction of branched PEI600 and stearic acid mediated by N, N'-carbonyldiimidazole (CDI). The MBs’ concentration, size distribution, stability and zeta potential (ζ-potential) were measured and the DNA loading capacity was examined as a function of the amount of Stearic-PEI600. The gene transfection efficiency and cytotoxicity were also examined using breast cancer MCF-7 cells via the reporter plasmid pCMV-Luc, encoding the firefly luciferase gene. The results showed that the Stearic-PEI600 polymer caused a significant increase in magnitude of ζ-potential of MBs. The addition of DNA into cationic MBs can shift ζ-potentials from positive to negative values. The DNA loading capacity of the MBs grew linearly from (5±0.2) ×10⁻³ pg/µm² to (20±1.8) ×10⁻³ pg/µm² when Stearic-PEI600 was increased from 5 mol% to 30 mol%. Transfection of MCF-7 cells using 5% PEI600 MBs plus ultrasound exposure yielded 5.76±2.58×10³ p/s/cm²/sr average radiance intensity, was 8.97- and 7.53-fold higher than those treated with plain MBs plus ultrasound (6.41±5.82) ×10² p/s/cm²/sr, (P<0.01) and PEI600 MBs without ultrasound (7.65±6.18) ×10² p/s/cm²/sr, (P<0.01), respectively. However, the PEI600 MBs showed slightly higher cytotoxicity than plain MBs. The cells treated with PEI600-MBs and plain MBs plus ultrasound showed 59.5±6.1% and 71.4±7.1% cell viability, respectively. In conclusion, our study demonstrated that the novel cationic MBs were able to increase DNA loading capacity and gene transfection efficiency and could be potentially applied in targeted gene delivery and therapy.

Gene therapy for cardiovascular disease mediated by ultrasound and microbubbles

Gene therapy provides an efficient approach for treatment of cardiovascular disease. To realize the therapeutic effect, both efficient delivery to the target cells and sustained expression of transgenes are required. Ultrasound targeted microbubble destruction (UTMD) technique has become a potential strategy for target-specific gene and drug delivery. When gene-loaded microbubble is injected, the ultrasound-mediated microbubble destruction may spew the transported gene to the targeted cells or organ. Meanwhile, high amplitude oscillations of microbubbles increase the permeability of capillary and cell membrane, facilitating uptake of the released gene into tissue and cell. Therefore, efficiency of gene therapy can be significantly improved. To date, UTMD has been successfully investigated in many diseases, and it has achieved outstanding progress in the last two decades. Herein, we discuss the current status of gene therapy of cardiovascular diseases, and reviewed the progress of the delivery of genes to cardiovascular system by UTMD.

Contrast ultrasound and targeted microbubbles: diagnostic and therapeutic applications in progressive diabetic nephropathy

Diabetic nephropathy remains one of the most common causes for end-stage renal disease worldwide. Although therapies aimed at optimizing glycemic control and systemic blood pressure have benefit, the reduction in progressive nephropathy remains modest at best. Thus, research continues to focus on newer therapies to address the unmet needs for additional renal protective strategies. The ability to noninvasively image the molecular and cellular processes that underlie diabetic nephropathy would be useful in risk stratifying patients with diabetes, and more importantly would aid in the evaluation of novel therapies to prevent and treat nephropathy. In addition, the development of ultrasound technologies that allow targeted gene delivery using high-power ultrasound and DNA-bearing microbubbles may have applicability for gene therapy to prevent diabetic nephropathy. This review highlights contrast-enhanced ultrasound imaging techniques for the evaluation of renal pathologies, including perfusion and molecular imaging techniques, and ultrasound-mediated gene delivery for therapeutic applications in diabetic nephropathy, that have potential for translation to clinical practice.

Ultrasound-mediated drug delivery for cardiovascular disease

INTRODUCTION

Ultrasound (US) has been developed as both a valuable diagnostic tool and a potent promoter of beneficial tissue bioeffects for the treatment of cardiovascular disease. These effects can be mediated by mechanical oscillations of circulating microbubbles, or US contrast agents, which may also encapsulate and shield a therapeutic agent in the bloodstream. Oscillating microbubbles can create stresses directly on nearby tissue or induce fluid effects that effect drug penetration into vascular tissue, lyse thrombi or direct drugs to optimal locations for delivery.

AREAS COVERED

The present review summarizes investigations that have provided evidence for US-mediated drug delivery as a potent method to deliver therapeutics to diseased tissue for cardiovascular treatment. In particular, the focus will be on investigations of specific aspects relating to US-mediated drug delivery, such as delivery vehicles, drug transport routes, biochemical mechanisms and molecular targeting strategies.

EXPERT OPINION

These investigations have spurred continued research into alternative therapeutic applications, such as bioactive gas delivery and new US technologies. Successful implementation of US-mediated drug delivery has the potential to change the way many drugs are administered systemically, resulting in more effective and economical therapeutics, and less-invasive treatments.

Study of the UTMD-based delivery system to induce cervical cancer cell apoptosis and inhibit proliferation with shRNA targeting Survivin

Apoptosis induction by short hairpin RNA (shRNA) expression vectors could be an efficient and promising strategy for cancer gene therapy. Ultrasound-targeted microbubble destruction (UTMD) is an appealing technique. In this study, we investigated the apoptosis induction and suppression of cell proliferation in vivo transfected by the UTMD-based shRNA delivery system. Nude mice with transplanted tumors of cervical cancer were randomly arranged into three groups: control group, plasmid injection and ultrasound (P + US), P + UTMD group. Expressions of Survivin and proliferating cell nuclear antigen (PCNA), Bcl-2, Bax, Caspase-3, Ki-67, nucleostemin (NS) were investigated by immunohistochemistry. Furthermore, microvessel density (MVD) was detected by CD34 protein expressions and apoptotic index (AI) was measured by TUNEL. As compared with those in the control and P + US groups, protein expressions of PCNA, Ki-67, Bcl-2, Survivin and NS in P + UTMD groups were down-regulated markedly, while those of Bax, Caspase-3 were up-regulated significantly (p < 0.05). MVD decreased significantly, whereas AI increased remarkably (p < 0.05). We suggested that UTMD-based shRNA delivery system could induce apoptosis and inhibit proliferation significantly, without causing any apparently adverse effect, representing a new, promising technology that would be used in the future gene therapy and research.

Ultrasound-mediated vascular gene transfection by cavitation of endothelial-targeted cationic microbubbles

OBJECTIVES

Ultrasound-mediated gene delivery can be amplified by acoustic disruption of microbubble carriers that undergo cavitation. We hypothesized that endothelial targeting of microbubbles bearing cDNA is feasible and, through optimizing proximity to the vessel wall, increases the efficacy of gene transfection.

BACKGROUND

Contrast ultrasound-mediated gene delivery is a promising approach for site-specific gene therapy, although there are concerns with the reproducibility of this technique and the safety when using high-power ultrasound.

METHODS

Cationic lipid-shelled decafluorobutane microbubbles bearing a targeting moiety were prepared and compared with nontargeted microbubbles. Microbubble targeting efficiency to endothelial adhesion molecules (P-selectin or intercellular adhesion molecule [ICAM]-1) was tested using in vitro flow chamber studies, intravital microscopy of tumor necrosis factor-alpha (TNF-α)-stimulated murine cremaster muscle, and targeted contrast ultrasound imaging of P-selectin in a model of murine limb ischemia. Ultrasound-mediated transfection of luciferase reporter plasmid charge coupled to microbubbles in the post-ischemic hindlimb muscle was assessed by in vivo optical imaging.

RESULTS

Charge coupling of cDNA to the microbubble surface was not influenced by the presence of targeting ligand, and did not alter the cavitation properties of cationic microbubbles. In flow chamber studies, surface conjugation of cDNA did not affect attachment of targeted microbubbles at microvascular shear stresses (0.6 and 1.5 dyne/cm(2)). Attachment in vivo was also not affected by cDNA according to intravital microscopy observations of venular adhesion of ICAM-1-targeted microbubbles and by ultrasound molecular imaging of P-selectin-targeted microbubbles in the post-ischemic hindlimb in mice. Transfection at the site of high acoustic pressures (1.0 and 1.8 MPa) was similar for control and P-selectin-targeted microbubbles but was associated with vascular rupture and hemorrhage. At 0.6 MPa, there were no adverse bioeffects, and transfection was 5-fold greater with P-selectin-targeted microbubbles.

CONCLUSIONS

We conclude that ultrasound-mediated transfection at safe acoustic pressures can be markedly augmented by endothelial juxtaposition.

Cyclic adenosine monophosphate response-element binding protein activation by mitogen-activated protein kinase-activated protein kinase 3 and four-and-a-half LIM domains 5 plays a key role for vein graft intimal hyperplasia

OBJECTIVE

Intimal hyperplasia (IH) is the main cause of vein graft stenosis or failure after bypass surgery. Basic investigations are proceeding in an animal model of mechanically desquamated arteries, and numerous molecules for potential IH treatments have been identified; however, neither insights into the mechanism of IH nor substantially effective treatments for its suppression have been developed. The goals of the present study are to use human vein graft samples to identify therapeutic target genes that control IH and to investigate the therapeutic efficacy of these candidate molecules in animal models.

METHODS

Using microarray analysis of human vein graft samples, we identified two previously unrecognized IH-related genes, mitogen-activated protein kinase-activated protein kinase 3 (MAPKAPK3) and four-and-a-half LIM domains 5 (FHL5).

RESULTS

Transfer of either candidate gene resulted in significantly elevated vascular smooth muscle cell (VSMC) proliferation and migration. Interestingly, cotransfection of both genes increased VSMC proliferation in an additive manner. These genes activated cyclic adenosine monophosphate response-element (CRE) binding protein (CREB), but their mechanisms of activation were different. MAPKAPK3 phosphorylated CREB, but FHL5 bound directly to CREB. A CREB dominant-negative protein, KCREB, which blocks its ability to bind CRE, repressed VSMC proliferation and migration. In a wire-injury mouse model, gene transfer of KCREB plasmid significantly repressed IH. In this vessel tissue, CRE-activated gene expression was repressed. Furthermore, we confirmed the changes in MAPKAPK3 and FHL5 expression using vein graft samples from eight patients.

CONCLUSIONS

We successively identified two previously unrecognized IH activators, MAPKAPK3 and FHL5, using human vein graft samples. Gene transfer of KCREB repressed IH in an animal model. Inhibition of CREB function is a promising gene therapy strategy for IH.

Contrast ultrasound imaging of the aorta alters vascular morphology and circulating von Willebrand factor in hypercholesterolemic rabbits

OBJECTIVES

Ultrasound contrast agents (UCAs) are intravenously infused microbubbles that add definition to ultrasonic images. Ultrasound contrast agents continue to show clinical promise in cardiovascular imaging, but their biological effects are not known with confidence. We used a cholesterol-fed rabbit model to evaluate these effects when used in conjunction with ultrasound (US) to image the descending aorta.

METHODS

Male New Zealand White rabbits (n = 41) were weaned onto an atherogenic diet containing 1% cholesterol, 10% fat, and 0.11% magnesium. At 21 days, rabbits were exposed to contrast US at 1 of 4 pressure levels using either the UCA Definity (Lantheus Medical Imaging, Inc, North Billerica, MA) or a saline control (n = 5 per group). Blood samples were collected and analyzed for lipids and von Willebrand factor (vWF), a marker of endothelial function. Animals were euthanized at 42 days, and tissues were collected for histologic analysis.

RESULTS

After adjustment for pre-exposure vWF, high-level US (in situ [at the aorta] peak rarefactional pressure of 1.4 or 2.1 MPa) resulted in significantly lower vWF 1 hour post exposure (P = .0127; P(adj) < .0762). This difference disappeared within 24 hours. Atheroma thickness in the descending aorta was lower in animals receiving the UCA compared to animals receiving saline.

CONCLUSIONS

Contrast US affected the descending aorta, as evidenced by two separate outcome measures. These results may be a first step in elucidating a previously unknown biological effect of UCAs. Further research is warranted to characterize the effects of this procedure.

In vivo temperature controlled ultrasound-mediated intracellular delivery of cell-impermeable compounds

Many chemotherapeutic drugs are characterized by high systemic toxicity and/or suffer from limited bioavailability. Thermosensitive liposomes (TSLs) encapsulating drugs in their aqueous lumen are promising activatable nanocarriers for ultrasound (US)-mediated drug delivery in response to mild hyperthermia. On the other hand, US is known to locally break biological barriers and as a consequence enable internalization of molecules. In this work, a two-step protocol for intracellular delivery of cell-impermeable molecules comprising of US-induced permeabilization followed by temperature-controlled release of the model drug from thermosensitive liposomes has been developed. TSLs containing TO-PRO-3, a cell-impermeable molecule that displays a significant increase in fluorescence upon binding to nucleic acids thus serving as a 'sensor' for internalization have been prepared and characterized in detail. US-mediated permeabilization followed by temperature-controlled release was applied to tumor bearing mice following i.v. injection of TSLs and microbubbles. The efficacy of this approach was evaluated by in vivo fluorescence imaging followed by histological analysis. A 2.4-fold increase of fluorescence signal was observed and intracellular delivery of TO-PRO-3 was confirmed by a characteristic nuclear staining. These results demonstrate the feasibility of novel drug delivery system to tumors comprising of local cell permeabilization by US followed by in situ release of the payload from thermosensitive liposomes. Possible applications include local and controlled intracellular delivery of molecules with otherwise limited bioavailability.

Adjuvant early and late cardioprotective therapy: access to the heart

Coronary heart disease is still the leading cause of death in industrialized nations, occurring either as acute coronary occlusion and myocardial infarction or as chronic ischaemic cardiomyopathy caused by continuous obstruction of one or more coronary arteries. Even after successful reperfusion, an additional loss of otherwise vital cardiomyocytes may occur in the primary ischaemic area, called lethal reperfusion injury. In experimental settings, delivery of therapeutic agents targeting the reperfusion injury reduces the infarct size by 30%. In addition to the choice of therapeutic agent and time point, the mode of application may be crucial for the therapeutic success. Therefore, this review focuses on the current and future administration techniques for early and late post-myocardial infarction therapies.

Ultrasound microbubble-mediated delivery of the siRNAs targeting MDR1 reduces drug resistance of yolk sac carcinoma L2 cells

Background

MDR1 gene encoding P-glycoprotein is an ATP-dependent drug efflux transporter and related to drug resistance of yolk sac carcinoma. Ultrasound microbubble-mediated delivery has been used as a novel and effective gene delivery method. We hypothesize that small interfering RNA (siRNA) targeting MDR1 gene (siMDR1) delivery with microbubble and ultrasound can down-regulate MDR1 expression and improve responsiveness to chemotherapeutic drugs for yolk sac carcinoma in vitro.

Methods

Retroviral knockdown vector pSEB-siMDR1s containing specific siRNA sites targeting rat MDR1 coding region were constructed and sequence verified. The resultant pSEB-siMDR1 plasmids DNA were encapsulated with lipid microbubble and the DNA release were triggered by ultrasound when added to culture cells. GFP positive cells were counted by flow cytometry to determine transfection efficiency. Quantitative real-time PCR and western blot were performed to determine the mRNA and protein expression of MDR1. P-glycoprotein function and drug sensitivity were analyzed by Daunorubicin accumulation and MTT assays.

Results

Transfection efficiency of pSEB-siMDR1 DNA was significantly increased by ultrasound microbubble-mediated delivery in rat yolk sac carcinoma L2 (L2-RYC) cells. Ultrasound microbubble-mediated siMDR1s delivery effectively inhibited MDR1 expression at both mRNA and protein levels and decreased P-glycoprotein function. Silencing MDR1 led to decreased cell viability and IC₅₀ of Vincristine and Dactinomycin.

Conclusions

Our results demonstrated that ultrasound microbubble-mediated delivery of MDR1 siRNA was safe and effective in L2-RYC cells. MDR1 silencing led to decreased P-glycoprotein activity and drug resistance of L2-RYC cells, which may be explored as a novel approach of combined gene and chemotherapy for yolk sac carcinoma.

See, reach, treat: ultrasound-triggered image-guided drug delivery

The integration of therapeutic interventions with diagnostic imaging has been recognized as one of the next technological developments that will have a major impact on medical treatments. Therapeutic applications using ultrasound, for example thermal ablation, hyperthermia or ultrasound-induced drug delivery, are examples for image-guided interventions that are currently being investigated. While thermal ablation using magnetic resonance-guided high-intensity focused ultrasound is entering the clinic, ultrasound-mediated drug delivery is still in a research phase, but holds promise to enable new applications in localized treatments. The use of ultrasound for the delivery of drugs has been demonstrated, particularly in the field of cardiology and oncology for a variety of therapeutics ranging from small-molecule drugs to biologics and nucleic acids exploiting temperature- or pressure-mediated delivery schemes.

Emerging diagnostic and therapeutic molecular imaging applications in vascular disease

Assessment of vascular disease has evolved from mere indirect and direct measurements of luminal stenosis to sophisticated imaging methods to depict millimeter structural changes of the vasculature. In the near future, the emergence of multimodal molecular imaging strategies may enable robust therapeutic and diagnostic ('theragnostic') approaches to vascular diseases that comprehensively consider structural, functional, biological and genomic characteristics of the disease in individualized risk assessment, early diagnosis and delivery of targeted interventions.This review presents a summary of recent preclinical and clinical developments in molecular imaging and theragnostic applications covering diverse atherosclerosis events such as endothelial activation, macrophage inflammatory activity, plaque neovascularization and arterial thrombosis. The main focus is on molecular targets designed for imaging platforms commonly used in clinical medicine including magnetic resonance, computed tomography and positron emission tomography. A special emphasis is given to vascular ultrasound applications, considering the important role this imaging platform plays in the clinical and research practice of the vascular medicine specialty.