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Gene therapy for ocular diseases meditated by ultrasound and microbubbles (Review).

Wan C, Li F, Li H - Mol Med Rep (2015)

Bottom Line: Ultrasound‑targeted microbubble destruction (UTMD), with the advantages of high safety, repetitive applicability and tissue targeting, has become a potential strategy for gene‑ and drug delivery.High‑amplitude oscillations of microbubbles act as cavitation nuclei which can effectively focus ultrasound energy, produce oscillations and disruptions that increase the permeability of the cell membrane and create transient pores in the cell membrane.In addition, appropriately powered, focused ultrasound combined with microbubbles can induce a reversible disruption of the blood‑retinal barrier with no significant side effects.

View Article: PubMed Central - PubMed

Affiliation: Department of Ultrasound, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, P.R. China.

ABSTRACT
The eye is an ideal target organ for gene therapy as it is easily accessible and immune‑privileged. With the increasing insight into the underlying molecular mechanisms of ocular diseases, gene therapy has been proposed as an effective approach. Successful gene therapy depends on efficient gene transfer to targeted cells to prove stable and prolonged gene expression with minimal toxicity. At present, the main hindrance regarding the clinical application of gene therapy is not the lack of an ideal gene, but rather the lack of a safe and efficient method to selectively deliver genes to target cells and tissues. Ultrasound‑targeted microbubble destruction (UTMD), with the advantages of high safety, repetitive applicability and tissue targeting, has become a potential strategy for gene‑ and drug delivery. When gene‑loaded microbubbles are injected, UTMD is able to enhance the transport of the gene to the targeted cells. High‑amplitude oscillations of microbubbles act as cavitation nuclei which can effectively focus ultrasound energy, produce oscillations and disruptions that increase the permeability of the cell membrane and create transient pores in the cell membrane. Thereby, the efficiency of gene therapy can be significantly improved. The UTMD‑mediated gene delivery system has been widely used in pre‑clinical studies to enhance gene expression in a site‑specific manner in a variety of organs. With reasonable application, the effects of sonoporation can be spatially and temporally controlled to improve localized tissue deposition of gene complexes for ocular gene therapy applications. In addition, appropriately powered, focused ultrasound combined with microbubbles can induce a reversible disruption of the blood‑retinal barrier with no significant side effects. The present review discusses the current status of gene therapy of ocular diseases as well as studies on gene therapy of ocular diseases meditated by UTMD.

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Related in: MedlinePlus

Microscopic images of rat conjunctiva following exposure to bubble liposomes and US. (A) Light microscopic image of hematoxylin- and eosin-stained tissue (magnification, x20). (B) Fluorescent microscopic examination showed that GFP was present in spindle- to round-shaped cells beneath the conjunctival epithelium of the area exposed to US with no obvious tissue damage (magnification, x20). Arrowheads indicate conjunctival stroma and asterisks indicate epithelium of conjunctiva. (C) Enlarged section of B marked by white square (magnification, x40). GFP was mainly located in the cytoplasm of these cells (arrow). Image taken from Yamashita et al (45). US, ultrasound; GFP, green fluorescence protein.
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f2-mmr-12-04-4803: Microscopic images of rat conjunctiva following exposure to bubble liposomes and US. (A) Light microscopic image of hematoxylin- and eosin-stained tissue (magnification, x20). (B) Fluorescent microscopic examination showed that GFP was present in spindle- to round-shaped cells beneath the conjunctival epithelium of the area exposed to US with no obvious tissue damage (magnification, x20). Arrowheads indicate conjunctival stroma and asterisks indicate epithelium of conjunctiva. (C) Enlarged section of B marked by white square (magnification, x40). GFP was mainly located in the cytoplasm of these cells (arrow). Image taken from Yamashita et al (45). US, ultrasound; GFP, green fluorescence protein.

Mentions: The cornea is an ideal tissue for studies on gene transfer, as it is transparent and avascular. Sonoda et al (9) investigated the practical efficacy and safety of ultrasound plus microbubble-mediated gene transfer to cornea in vitro and in vivo. While treatment with DNA alone did not lead to any gene transfer into the cultured corneal epithelial cell line RC-1, ultrasound slightly enhanced gene transfer, and ultrasound plus microbubbles significantly increased the gene transfer efficiency. In the in vivo study, ultrasound plus microbubbles markedly increased gene transfer efficiency without any apparent tissue damage. Green fluorescence protein (GFP)-positive cells were observed exclusively where ultrasound had been applied and GFP was mainly present in spindle-shaped cells in the targeted regions of the corneal stroma (Fig. 1) (10). Yamashita et al (45) used a novel bubble liposome (BL) composed of a polyethylenglycol (PEG)-modified liposome containing perfluoropropane gas, with ultrasound to transport GFP into rabbit RC-1 cells in vitro and conjunctiva in vivo. The study showed that BL with US effectively transferred genes into cultured corneal epithelial cells and rat sub-conjunctival tissue without causing any apparently adverse effects. Diffuse fluorescence-positive granules were present in sub-conjunctival tissues and no tissue damage was observed histologically (Fig. 2).


Gene therapy for ocular diseases meditated by ultrasound and microbubbles (Review).

Wan C, Li F, Li H - Mol Med Rep (2015)

Microscopic images of rat conjunctiva following exposure to bubble liposomes and US. (A) Light microscopic image of hematoxylin- and eosin-stained tissue (magnification, x20). (B) Fluorescent microscopic examination showed that GFP was present in spindle- to round-shaped cells beneath the conjunctival epithelium of the area exposed to US with no obvious tissue damage (magnification, x20). Arrowheads indicate conjunctival stroma and asterisks indicate epithelium of conjunctiva. (C) Enlarged section of B marked by white square (magnification, x40). GFP was mainly located in the cytoplasm of these cells (arrow). Image taken from Yamashita et al (45). US, ultrasound; GFP, green fluorescence protein.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581786&req=5

f2-mmr-12-04-4803: Microscopic images of rat conjunctiva following exposure to bubble liposomes and US. (A) Light microscopic image of hematoxylin- and eosin-stained tissue (magnification, x20). (B) Fluorescent microscopic examination showed that GFP was present in spindle- to round-shaped cells beneath the conjunctival epithelium of the area exposed to US with no obvious tissue damage (magnification, x20). Arrowheads indicate conjunctival stroma and asterisks indicate epithelium of conjunctiva. (C) Enlarged section of B marked by white square (magnification, x40). GFP was mainly located in the cytoplasm of these cells (arrow). Image taken from Yamashita et al (45). US, ultrasound; GFP, green fluorescence protein.
Mentions: The cornea is an ideal tissue for studies on gene transfer, as it is transparent and avascular. Sonoda et al (9) investigated the practical efficacy and safety of ultrasound plus microbubble-mediated gene transfer to cornea in vitro and in vivo. While treatment with DNA alone did not lead to any gene transfer into the cultured corneal epithelial cell line RC-1, ultrasound slightly enhanced gene transfer, and ultrasound plus microbubbles significantly increased the gene transfer efficiency. In the in vivo study, ultrasound plus microbubbles markedly increased gene transfer efficiency without any apparent tissue damage. Green fluorescence protein (GFP)-positive cells were observed exclusively where ultrasound had been applied and GFP was mainly present in spindle-shaped cells in the targeted regions of the corneal stroma (Fig. 1) (10). Yamashita et al (45) used a novel bubble liposome (BL) composed of a polyethylenglycol (PEG)-modified liposome containing perfluoropropane gas, with ultrasound to transport GFP into rabbit RC-1 cells in vitro and conjunctiva in vivo. The study showed that BL with US effectively transferred genes into cultured corneal epithelial cells and rat sub-conjunctival tissue without causing any apparently adverse effects. Diffuse fluorescence-positive granules were present in sub-conjunctival tissues and no tissue damage was observed histologically (Fig. 2).

Bottom Line: Ultrasound‑targeted microbubble destruction (UTMD), with the advantages of high safety, repetitive applicability and tissue targeting, has become a potential strategy for gene‑ and drug delivery.High‑amplitude oscillations of microbubbles act as cavitation nuclei which can effectively focus ultrasound energy, produce oscillations and disruptions that increase the permeability of the cell membrane and create transient pores in the cell membrane.In addition, appropriately powered, focused ultrasound combined with microbubbles can induce a reversible disruption of the blood‑retinal barrier with no significant side effects.

View Article: PubMed Central - PubMed

Affiliation: Department of Ultrasound, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, P.R. China.

ABSTRACT
The eye is an ideal target organ for gene therapy as it is easily accessible and immune‑privileged. With the increasing insight into the underlying molecular mechanisms of ocular diseases, gene therapy has been proposed as an effective approach. Successful gene therapy depends on efficient gene transfer to targeted cells to prove stable and prolonged gene expression with minimal toxicity. At present, the main hindrance regarding the clinical application of gene therapy is not the lack of an ideal gene, but rather the lack of a safe and efficient method to selectively deliver genes to target cells and tissues. Ultrasound‑targeted microbubble destruction (UTMD), with the advantages of high safety, repetitive applicability and tissue targeting, has become a potential strategy for gene‑ and drug delivery. When gene‑loaded microbubbles are injected, UTMD is able to enhance the transport of the gene to the targeted cells. High‑amplitude oscillations of microbubbles act as cavitation nuclei which can effectively focus ultrasound energy, produce oscillations and disruptions that increase the permeability of the cell membrane and create transient pores in the cell membrane. Thereby, the efficiency of gene therapy can be significantly improved. The UTMD‑mediated gene delivery system has been widely used in pre‑clinical studies to enhance gene expression in a site‑specific manner in a variety of organs. With reasonable application, the effects of sonoporation can be spatially and temporally controlled to improve localized tissue deposition of gene complexes for ocular gene therapy applications. In addition, appropriately powered, focused ultrasound combined with microbubbles can induce a reversible disruption of the blood‑retinal barrier with no significant side effects. The present review discusses the current status of gene therapy of ocular diseases as well as studies on gene therapy of ocular diseases meditated by UTMD.

Show MeSH
Related in: MedlinePlus