Nonviral Vectors for Gene Therapy (eBook)

Physical Methods and Medical Translation

Leaf Huang, Dexi Liu, Ernst Wagner (Herausgeber)

eBook Download: PDF | EPUB

2015 | 1. Auflage
296 Seiten
Elsevier Science (Verlag)
978-0-12-802470-6 (ISBN)

The field of genetics is rapidly evolving, and new medical breakthroughs are occurring as a result of advances in our knowledge of genetics. Advances in Genetics continually publishes important reviews of the broadest interest to geneticists and their colleagues in affiliated disciplines.

Includes methods for testing with ethical, legal, and social implications
Critically analyzes future directions
Written and edited by recognized leaders in the field

The field of genetics is rapidly evolving, and new medical breakthroughs are occurring as a result of advances in our knowledge of genetics. Advances in Genetics continually publishes important reviews of the broadest interest to geneticists and their colleagues in affiliated disciplines. Includes methods for testing with ethical, legal, and social implications Critically analyzes future directions Written and edited by recognized leaders in the field

Chapter Two

Nonviral Gene Delivery Systems by the Combination of Bubble Liposomes and Ultrasound

Daiki Omata∗, Yoichi Negishi§, Ryo Suzuki∗, Yusuke Oda∗, Yoko Endo-Takahashi§ and Kazuo Maruyama∗,1 ∗Department of Drug and Gene Delivery Research, Faculty of Pharma-Sciences, Teikyo University, Itabashi, Tokyo, Japan §Department of Drug Delivery and Molecular Biopharmaceutics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
1 Corresponding author: E-mail: maruyama@pharm.teikyo-u.ac.jp

Abstract

The combination of therapeutic ultrasound (US) and nano/microbubbles is an important system for establishing a novel and noninvasive gene delivery system. Genes are delivered more efficiently using this system compared with a conventional nonviral vector system such as the lipofection method, resulting in higher gene expression. This higher efficiency is due to the gene being delivered into the cytosol and bypassing the endocytosis pathway. Many in vivo studies have demonstrated US-mediated gene delivery with nano/microbubbles, and several gene therapy feasibility studies for various diseases have been reported. In addition, nano/microbubbles can deliver genes site specifically by the control of US exposure site. In the present review, we summarize the gene delivery systems by the combination of nano/microbubbles and US, describe their properties, and assess applications and challenges of US theranostics.

Keywords

Cavitation; Microbubble; mRNA; Nanobubble; Non-viral gene delivery systems; siRNA; Sonopolation; Theranostics; Ultrasound

1. Introduction

Gene therapy has potential for treating cancer and genetic diseases. Viral vectors are investigated and shown effective for gene transduction, but some problems have become evident (Check, 2002, 2003; Marshall, 1999). Delivery vectors that are highly efficient for gene transduction must also be safe and easy to use. Nonviral vectors have recently received attention as gene carriers, but their transduction efficiency is very low, although efforts have been made to address this (Itaka et al., 2007; Kogure, Akita, Yamada, & Harashima, 2008; Liu, Conwell, Yuan, Shollenberger, & Huang, 2007). Toward this end, ultrasound (US) has been investigated for improving the efficiency of transgene delivery and holds promise as a means of generating a noninvasive gene delivery system.

Sonoporation improves the efficiency of gene delivery into tissues and cells by perturbing the cell membrane and causing transient pores to open in the membrane, thus facilitating gene entry into the cell (Fechheimer et al., 1987; Miller, Miller, & Brayman, 1996). In addition, it has been reported that microbubbles, used as US contrast agents play an important role in enhancing the efficiency of gene delivery without causing cell damage (Greenleaf, Bolander, Sarkar, Goldring, & Greenleaf, 1998). In general, cell damage is dependent on the US intensity, the exposure time, the concentration of microbubbles, and the cell type, with US intensity and exposure time being particularly important. Therefore, effective US-mediated gene delivery requires the optimization of the US exposure conditions (Feril, Ogawa, Tachibana, & Kopndo, 2006; Li, Tachibana, Kuroki, & Kuroki, 2003; Pislaru et al., 2003; Suzuki, Takizawa, Negishi, et al., 2008). Some researchers studied about the cell damage by the disruption of microbubbles with US exposure (Feril et al., 2003; Guo et al., 2006; Hassan et al., 2009, 2010; Kudo, Okada, & Yamamoto, 2009; Wells, 2010). These reports provide important information for US-mediated gene delivery utilizing microbubbles.

Microbubbles are destroyed by exposure to US, generating microstreams or microjets which result in shear stress to cells and the generation of transient holes in the cell membrane (Taniyama et al., 2002). Since this approach can be used to deliver extracellular material such as genes into cells, microbubbles could facilitate US-mediated gene delivery. In addition, submicron-sized bubbles (nanobubbles), which are smaller than conventional microbubbles, were recently reported (Gao, Kennedy, Christensen, & Rapoport, 2008; Wang, Li, Zhou, Huang, & Xu, 2010), and we have developed novel liposomal nanobubbles (bubble liposomes (BLs)) (Negishi et al., 2008; Suzuki et al., 2009, 2010; Suzuki & Maruyama, 2010; Suzuki, Takizawa, Kuwata, et al., 2008; Suzuki, Takizawa, Negishi, et al., 2008; Suzuki, Takizawa, Negishi, Hagisawa, et al., 2007; Suzuki, Takizawa, Negishi, Utoguchi, et al., 2007; Un et al., 2010; Yamashita et al., 2007). These nanobubbles can also be used to enhance the efficiency of US-mediated gene delivery. In this review, we describe US-mediated delivery systems combined with nano/microbubbles and discuss their feasibility as nonviral vector systems.

2. Microbubbles and Ultrasound

The behavior of microbubbles depends on the amplitude of the US used. Very low acoustic pressure (mechanical index (MI) < 0.05–0.1) induces linear oscillation of the microbubble, and the reflected frequency is equal to the transmitted frequency (Figure 1(A)). An increase in acoustic pressure (0.1 < MI < 0.3), referred to as low-power imaging, causes nonlinear expansion and compression of the microbubble (Figure 1(B)). The bubble is somewhat more resistant to compression than to expansion, a phenomenon known as stable or noninertial cavitation, resulting in the emission of nonlinear harmonic signals at multiples of the transmitted frequency (Unger, Hersh, Vannan, Matsunaga, & McCreery, 2001). Harmonic imaging with microbubbles enhances the bubble-to-tissue backscatter signal ratio due to insignificant harmonic backscatter from tissue in this range of MI. Therefore, this technique can improve the signal-noise ratio and be useful in left ventricular pacification imaging (Mulvagh et al., 2000). In addition, stable or noninertial cavitation can enhance transient cell membrane permeability (Figure 2(A)) (van Wamel et al., 2006). Machluf et al. reported that the exposure of cells to US (0.16 MI, 1 MHz) in the presence of microbubbles resulted in the delivery of plasmid DNA (pDNA) into the cells (Duvshani-Eshet, Adam, et al., 2006; Duvshani-Eshet, Baruch, et al., 2006).

Figure 1 Schematics showing microbubble behavior in acoustic fields. (A) Very low intensity ultrasound (US) induces the linear oscillation of the microbubble. (B) Low intensity US induces the oscillation of the microbubble, with a gradual increase in the diameter of the microbubble. Stable oscillation occurs when the microbubble reaches its resonant diameter. (C) High intensity US causes a rapid increase in the diameter of the microbubble for a few cycles, which induces bubble disruption.

Figure 2 Schematics showing pore formation in the cell membrane by oscillating or disrupting microbubbles. (A) The pushing and pulling behavior (noninertial cavitation) of microbubbles and (B) the collapse of microbubbles (inertial cavitation) rupturing the cell membrane and creating pores allowing trans-membrane flux of fluid and macromolecules such as plasmid DNA and oligonucleotides (C).

Higher acoustic pressure (MI > 0.3–0.6) causes forced expansion and compression of the microbubble and results in bubble disruption (collapse) (Figure 1(C)). Bubble disruption by this inertial cavitation is utilized as flash-replenishment in reperfusion study of diagnosis (Kalantarinia, Belcik, Patrie, & Wei, 2009). This inertial cavitation induces microstreams/microjets around the bubbles. These microstreams/microjets can enhance the permeability of the cell membrane due to the formation of transient pores (Figure 2(B)) (Taniyama et al., 2002). In the presence of nano-/microbubbles, the threshold for cavitation decreases, allowing the destruction of the microbubbles at lower US energies.

3. Bubble Liposomes

As mentioned above, microbubbles are contrast agents used in US imaging. Microbubbles can also be used to improve transfection efficiency when combined with US. Microbubbles are generally unstable and have a mean diameter of between 1 and 6 μm, making them too large for intravascular applications (Lindner, 2004). Moreover, it is difficult to modify their surface with functional molecules. Therefore, microbubbles should be small and stable, and their surface should be easily modified with functional molecules for targeting.

Liposomes have several advantages as drug, antigen and gene delivery carriers as their size can be easily controlled, and they can be modified with targeting molecules. Therefore, we used liposome technology to develop novel BLs containing the US gas, perfluoropropane (Figure 3(A)). BLs are about 500 nm in diameter, making them smaller than Sonazoid which is...

Erscheint lt. Verlag	23.1.2015
Sprache	englisch
Themenwelt	Studium ► 2. Studienabschnitt (Klinik) ► Humangenetik
	Naturwissenschaften ► Biologie ► Genetik / Molekularbiologie
	Naturwissenschaften ► Biologie ► Zellbiologie
	Technik
ISBN-10	0-12-802470-4 / 0128024704
ISBN-13	978-0-12-802470-6 / 9780128024706

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