Modified Bovine Milk Exosomes for Doxorubicin Delivery to Triple-Negative Breast Cancer Cells

Biological nanoparticles, such as exosomes, offer an approach to drug delivery because of their innate ability to transport biomolecules. Exosomes are derived from cells and an integral component of cellular communication. However, the cellular cargo of human exosomes could negatively impact their use as a safe drug carrier. Additionally, exosomes have the intrinsic yet enigmatic, targeting characteristics of complex cellular communication. Hence, harnessing the natural transport abilities of exosomes for drug delivery requires predictably targeting these biological nanoparticles. This manuscript describes the use of two chemical modifications, incorporating a neuropilin receptor agonist peptide (iRGD) and a hypoxia-responsive lipid for targeting and release of an encapsulated drug from bovine milk exosomes to triple-negative breast cancer cells. Triple-negative breast cancer is a very aggressive and deadly form of malignancy with limited treatment options. Incorporation of both the iRGD peptide and hypoxia-responsive lipid into the lipid bilayer of bovine milk exosomes and encapsulation of the anticancer drug, doxorubicin, created the peptide targeted, hypoxia-responsive bovine milk exosomes, iDHRX. Initial studies confirmed the presence of iRGD peptide and the exosomes' ability to target the αvβ3 integrin, overexpressed on triple-negative breast cancer cells' surface. These modified exosomes were stable under normoxic conditions but fragmented in the reducing microenvironment created by 10 mM glutathione. In vitro cellular internalization studies in monolayer and three-dimensional (3D) spheroids of triple-negative breast cancer cells confirmed the cell-killing ability of iDHRX. Cell viability of 50% was reached at 10 μM iDHRX in the 3D spheroid models using four different triple-negative breast cancer cell lines. Overall, the tumor penetrating, hypoxia-responsive exosomes encapsulating doxorubicin would be effective in reducing triple-negative breast cancer cells' survival.

Echogenic Exosomes as ultrasound contrast agents

Exosomes are naturally secreted extracellular bilayer vesicles (diameter 40-130 nm), which have recently been found to play a critical role in cell-to-cell communication and biomolecule delivery. Their unique characteristics-stability, permeability, biocompatibility and low immunogenicity-have made them a prime candidate for use in delivering cancer therapeutics and other natural products. Here we present the first ever report of echogenic exosomes, which combine the benefits of the acoustic responsiveness of traditional microbubbles with the non-immunogenic and small-size morphology of exosomes. Microbubbles, although effective as ultrasound contrast agents, are restricted to intravascular usage due to their large size. In the current study, we have rendered bovine milk-derived exosomes echogenic by freeze drying them in the presence of mannitol. Ultrasound imaging and direct measurement of linear and nonlinear scattered responses were used to investigate the echogenicity and stability of the prepared exosomes. A commercial scanner registered enhancement (28.9% at 40 MHz) in the brightness of ultrasound images in presence of echogenic exosomes at 5 mg/mL. The exosomes also showed significant linear and nonlinear scattered responses-11 dB enhancement in fundamental, 8.5 dB in subharmonic and 3.5 dB in second harmonic all at 40 μg/mL concentration. Echogenic exosomes injected into the tail vein of mice and the synovial fluid of rats resulted in significantly higher brightness-as much as 300%-of the ultrasound images, showing their promise in a variety of in vivo applications. The echogenic exosomes, with their large-scale extractability from bovine milk, lack of toxicity and minimal immunogenic response, successfully served as ultrasound contrast agents in this study and offer an exciting possibility to act as an effective ultrasound responsive drug delivery system.

Human papillomavirus E6/E7 mRNA expression in women younger than 30 years of age

OBJECTIVE

The prevalence of human papillomavirus (HPV) is high in women younger than 30 years of age, most infections being transient. It is not clear, however, to what extent the E6/E7 transcripts are being expressed. This may be of prognostic importance. In this study, we have determined the prevalence of HPV DNA and mRNA in 283 women younger than 30 years of age.

METHODS

E6/E7 transcripts from HPV types 16, 18, 31, 33 and 45 were detected using PreTect HPV-Proofer, while the presence of HPV DNA was detected using Gp5+/6+ consensus PCR and type-specific PCR.

RESULTS

A total of 92 women (32.5%) were positive by consensus PCR, 59 (20.8%) were positive by type-specific PCR, while 41 (14.5%) were positive by PreTect HPV-Proofer. E6/E7 mRNA expression was detected in 38 (64.4%) of the 59 HPV type-specific DNA positive women. For HPV 16, E6/E7 mRNA expression was observed in 8 (32%) of the 25 DNA positive women. No high-grade lesions were observed in the concomitant cytology.

CONCLUSIONS

Among young women having a normal Pap smear, a high HPV prevalence was found. Hence, use of consensus PCR will most probably give a low prognostic value for identifying subsequent severe dysplasia. The five HPV types 16, 18, 31, 33 and 45 accounted for the majority of infections with two out of three having a detectable E6/E7 mRNA expression. Yet, repeated type-specific testing for HPV mRNA may identify young women with a persistent transforming infection being at increased risk for severe dysplasia.

Human papillomavirus oncogenic expression in the dysplastic portio; an investigation of biopsies from 190 cervical cones

In this study, we investigated the presence of E6/E7 transcripts of seven common high-risk human papillomavirus (HPV) types in 190 cervical biopsies. The RNA-based real-time nucleic acid sequence-based amplification assay (NASBA) and type-specific PCR, both detecting HPV 16, 18, 31, 33, 45, 52, and 58, as well as consensus PCR, were performed on all 190 biopsies. High accordance between type-specific and consensus PCR confirms that the HPV types included in this study are the most common types present in cervical dysplasia. Furthermore, we see a clear increase in the incidence of HPV, both DNA and RNA, along with the histological severity of dysplasia. HPV RNA was detected in all but two PCR-positive cases, confirming that the virus exerts E6/E7 mRNA expression in cases of high-grade dysplasia. Out of 19 women given a normal or borderline diagnosis at conisation, only four were found HPV positive, which may suggest that unnecessary conisations can possibly be reduced by introducing HPV testing into the preoperative routine assessment.