Ultrasound/microbubble-mediated targeted delivery of anticancer microRNA-loaded nanoparticles to deep tissues in pigs.

In this study, we designed and validated a platform for ultrasound and microbubble-mediated delivery of FDA-approved pegylated poly lactic-co-glycolic acid (PLGA) nanoparticles loaded with anticancer microRNAs (miRNAs) to deep tissues in a pig model. Small RNAs have been shown to reprogram tumor cells and sensitize them to clinically used chemotherapy. To overcome their short intravascular circulation half-life and achieve controlled and sustained release into tumor cells, anticancer miRNAs need to be encapsulated into nanocarriers. Focused ultrasound combined with gas-filled microbubbles provides a noninvasive way to improve the permeability of tumor vasculature and increase the delivery efficiency of drug-loaded particles. A single handheld, curvilinear ultrasound array was used in this study for image-guided therapy with clinical-grade SonoVue contrast agent. First, we validated the platform on phantoms to optimize the microbubble cavitation dose based on acoustic parameters, including peak negative pressure, pulse length, and pulse repetition frequency. We then tested the system in vivo by delivering PLGA nanoparticles co-loaded with antisense-miRNA-21 and antisense-miRNA-10b to pig liver and kidney. Enhanced miRNA delivery was observed (1.9- to 3.7-fold increase) as a result of the ultrasound treatment compared to untreated control regions. Additionally, we used highly fluorescent semiconducting polymer nanoparticles to visually assess nanoparticle extravasation. Fluorescent microscopy suggested the presence of nanoparticles in the extravascular compartment. Hematoxylin and eosin staining of treated tissues did not reveal tissue damage. The results presented in this manuscript suggest that the proposed platform may be used to safely and noninvasively enhance the delivery of miRNA-loaded nanoparticles to target regions in deep organs in large animal models.

Ultrasound-guided delivery of thymidine kinase-nitroreductase dual therapeutic genes by PEGylated-PLGA/PIE nanoparticles for enhanced triple negative breast cancer therapy.

AIM: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype. Since no targeted therapy is available, gene-directed enzyme prodrug therapy (GDEPT) could be an attractive strategy for treating TNBC. MATERIALS & METHODS: Polyethylene glycol (PEG)ylated-poly(lactic-co-glycolic acid)/polyethyleneimine nanoparticles (PLGA/PEI NPs) were synthesized and complexed with TK-NTR fusion gene. Ultrasound (US) and microbubble (MB) mediated sonoporation was used for efficient delivery of the TK-NTR-DNA-NP complex to TNBC tumor in vivo for cancer therapy. Therapeutic effect was evaluated by treating TNBC cells in vitro and tumor xenograft in vivo by using prodrugs ganciclovir (GCV) and CB1954. RESULTS: TNBC cells treated with GCV/CB1954 prodrugs after transfection of TK-NTR-DNA by PEGylated-PLGA/PEI NP resulted in high apoptotic-index. US-MB image-guided delivery of TK-NTR-DNA-NP complex displayed significant expression level of TK-NTR protein and showed tumor reduction when treated with GCV/CB1954 prodrugs in TNBC xenograft in vivo. CONCLUSION: US-MB image-guided delivery of TK-NTR gene by PEGylated-PLGA/PEI NPs could be a potential prodrug therapy for TNBC in the clinic.

Longitudinal assessment of ultrasound-guided complementary microRNA therapy of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the second-leading cause of cancer related deaths worldwide and new strategies to efficiently treat HCC are critically needed. The aim of this study was to assess the longitudinal treatment effects of two complementary miRNAs (miRNA-122 and antimiR-21) encapsulated in biodegradable poly lactic-co-glycolic acid (PLGA) - poly ethylene glycol (PEG) nanoparticles (PLGA-PEG-NPs), administered by an ultrasound-guided and microbubble-mediated delivery approach in doxorubicin-resistant and non-resistant human HCC xenografts. Using in vitro assays, we show that repeated miRNA treatments resulted in gradual reduction of HCC cell proliferation and reversal of doxorubicin resistance. Optimized US parameters resulted in a 9-16 fold increase (p = 0.03) in miRNA delivery in vivo in HCC tumors after two US treatments compared to tumors without US treatment. Furthermore, when combined with doxorubicin (10 mg/kg), longitudinal miRNA delivery showed a significant inhibition of tumor growth in both resistant and non-resistant tumors compared to non-treated, and doxorubicin treated controls. We also found that ultrasound-guided miRNA therapy was not only effective in inhibiting HCC tumor growth but also allowed lowering the dose of doxorubicin needed to induce apoptosis. In conclusion, the results of this study suggest that ultrasound-guided and MB-mediated delivery of miRNA-122 and antimiR-21, when combined with doxorubicin, is a highly effective approach to treat resistant HCC while reducing doxorubicin doses needed for treating non-resistant HCC in longitudinal treatment experiments. Further refinement of this strategy could potentially lead to better treatment outcomes for patients with HCC.

Ultrasound-guided therapeutic modulation of hepatocellular carcinoma using complementary microRNAs.

Treatment options for patients with hepatocellular carcinoma (HCC) are limited, in particular in advanced and drug resistant HCC. MicroRNAs (miRNA) are non-coding small RNAs that are emerging as novel drugs for the treatment of cancer. The aim of this study was to assess treatment effects of two complementary miRNAs (sense miRNA-122, and antisense antimiR-21) encapsulated in biodegradable poly (lactic-co-glycolic acid) nanoparticles (PLGA-NP), administered by an ultrasound-guided and microbubble-enhanced delivery approach in doxorubicin-resistant and non-resistant human HCC xenografts. Proliferation and invasiveness of human HCC cells after miRNA-122/antimiR-21 and doxorubicin treatment were assessed in vitro. Confocal microscopy and qRT-PCR were used to visualize and quantitate successful intracellular miRNA-loaded PLGA-NP delivery. Up and down-regulation of miRNA downstream targets and multidrug resistance proteins and extent of apoptosis were assessed in vivo in treated human HCC xenografts in mice. Compared to single miRNA therapy, combination therapy with the two complementary miRNAs resulted in significantly (P<0.05) stronger decrease in cell proliferation, invasion, and migration of HCC cells as well as higher resensitization to doxorubicin. Ultrasound-guided delivery significantly increased in vivo miRNA-loaded PLGA-NP delivery in human HCC xenografts compared to control conditions by 5-9 fold (P<0.001). miRNA-loaded PLGA-NP were internalized in HCC cells and anti-apoptotic proteins were down regulated with apoptosis in ~27% of the tumor volume of doxorubicin-resistant human HCC after a single treatment with complementary miRNAs and doxorubicin. Thus, ultrasound-guided delivery of complementary miRNAs is highly efficient in the treatment of doxorubicin- resistant and non-resistant HCC. Further development of this new treatment approach could aid in better treatment of patients with HCC.

Ultrasound-guided delivery of microRNA loaded nanoparticles into cancer.

Ultrasound induced microbubble cavitation can cause enhanced permeability across natural barriers of tumors such as vessel walls or cellular membranes, allowing for enhanced therapeutic delivery into the target tissues. While enhanced delivery of small (<1nm) molecules has been shown at acoustic pressures below 1MPa both in vitro and in vivo, the delivery efficiency of larger (>100nm) therapeutic carriers into cancer remains unclear and may require a higher pressure for sufficient delivery. Enhanced delivery of larger therapeutic carriers such as FDA approved pegylated poly(lactic-co-glycolic acid) nanoparticles (PLGA-PEG-NP) has significant clinical value because these nanoparticles have been shown to protect encapsulated drugs from degradation in the blood circulation and allow for slow and prolonged release of encapsulated drugs at the target location. In this study, various acoustic parameters were investigated to facilitate the successful delivery of two nanocarriers, a fluorescent semiconducting polymer model drug nanoparticle as well as PLGA-PEG-NP into human colon cancer xenografts in mice. We first measured the cavitation dose produced by various acoustic parameters (pressure, pulse length, and pulse repetition frequency) and microbubble concentration in a tissue mimicking phantom. Next, in vivo studies were performed to evaluate the penetration depth of nanocarriers using various acoustic pressures, ranging between 1.7 and 6.9MPa. Finally, a therapeutic microRNA, miR-122, was loaded into PLGA-PEG-NP and the amount of delivered miR-122 was assessed using quantitative RT-PCR. Our results show that acoustic pressures had the strongest effect on cavitation. An increase of the pressure from 0.8 to 6.9MPa resulted in a nearly 50-fold increase in cavitation in phantom experiments. In vivo, as the pressures increased from 1.7 to 6.9MPa, the amount of nanoparticles deposited in cancer xenografts was increased from 4- to 14-fold, and the median penetration depth of extravasated nanoparticles was increased from 1.3-fold to 3-fold, compared to control conditions without ultrasound, as examined on 3D confocal microscopy. When delivering miR-122 loaded PLGA-PEG-NP using optimal acoustic settings with minimum tissue damage, miR-122 delivery into tumors with ultrasound and microbubbles was 7.9-fold higher compared to treatment without ultrasound. This study demonstrates that ultrasound induced microbubble cavitation can be a useful tool for delivery of therapeutic miR loaded nanocarriers into cancer in vivo.