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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

Fluorescence and H&E staining images of the rabbit fundus oculi. (A) In the plasmid + BL without US group, no GFP-positive cells were observed. (B) In the plasmid + BL + US group, GFP-positive cells were observed exclusively in the area exposed to US and mainly located in the outer nuclear layer. (C) H&E staining showed no evident tissue damage after exposure of the intravitreal retina to BL with US. Scale bar, 100 µm. Image taken from Sonoda et al (13). H&E, hematoxylin and eosin; US, ultrasound; BL, bubble liposome; GFP, green fluorescence protein.
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f3-mmr-12-04-4803: Fluorescence and H&E staining images of the rabbit fundus oculi. (A) In the plasmid + BL without US group, no GFP-positive cells were observed. (B) In the plasmid + BL + US group, GFP-positive cells were observed exclusively in the area exposed to US and mainly located in the outer nuclear layer. (C) H&E staining showed no evident tissue damage after exposure of the intravitreal retina to BL with US. Scale bar, 100 µm. Image taken from Sonoda et al (13). H&E, hematoxylin and eosin; US, ultrasound; BL, bubble liposome; GFP, green fluorescence protein.

Mentions: Gene transfer provides a novel approach for the treatment of retinal diseases. Li et al (57) demonstrated that UTMD was able to safely and effectively deliver plasmids into RGCs in vitro. Under the optimum parameters, the average transfection rate of p enhanced (E)GFP-N1 with UTMD was 25%. Compared with the ultrasound plus plasmid group, the number of transfected cells increased by 28-fold. Another study reported that UTMD-mediated gene transfer of pigment epithelium-derived factor (PEDF) into retina and chorioids of rats inhibited the development of CNV (58). The study also demonstrated that in the short term (7 and 14 days after transfection), the transfection efficiency mediated by UTMD was not different from that achieved by liposome-based gene transfer. However, in the long term (28 days after transfection), the transfection efficiency by UTMD was significantly higher as compared with that of the liposome approach. The shock wave of UTMD promoted the delivery of the plasmid into the cell nucleus, which may partly be explained by the induction of tight binding of the target plasmid to the cell's endogenous DNA. UTMD therefore presents a solution for local gene transfection and reduces the amount of plasmid required. Sonoda et al (13) used a miniature ultrasound transducer to evaluate the efficacy of intravitreal ultrasound (SonoPore 4000) irradiation for selective GFP plasmid transfer into the rabbit retina. The ultrasound probe, as small as a 19-gauge needle, was inserted into the vitreous cavity through a scleral incision. The gene-transfer efficiency was quantified by counting the number of GFP-positive cells. The study demonstrated that the retinas that received plasmid with BL and ultrasound showed a significant increase in the number of GFP-positive cells without any apparent tissue damage (Fig. 3) (13). GFP-positive cells were observed exclusively in the area that was exposed to ultrasound, and no GFP-positive cells were observed in the control eyes that were not treated with ultrasound. These results indicated that gene delivery to the retina using intravitreal ultrasound exposure is more selective than the transcorneal method.


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

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

Fluorescence and H&E staining images of the rabbit fundus oculi. (A) In the plasmid + BL without US group, no GFP-positive cells were observed. (B) In the plasmid + BL + US group, GFP-positive cells were observed exclusively in the area exposed to US and mainly located in the outer nuclear layer. (C) H&E staining showed no evident tissue damage after exposure of the intravitreal retina to BL with US. Scale bar, 100 µm. Image taken from Sonoda et al (13). H&E, hematoxylin and eosin; US, ultrasound; BL, bubble liposome; GFP, green fluorescence protein.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3-mmr-12-04-4803: Fluorescence and H&E staining images of the rabbit fundus oculi. (A) In the plasmid + BL without US group, no GFP-positive cells were observed. (B) In the plasmid + BL + US group, GFP-positive cells were observed exclusively in the area exposed to US and mainly located in the outer nuclear layer. (C) H&E staining showed no evident tissue damage after exposure of the intravitreal retina to BL with US. Scale bar, 100 µm. Image taken from Sonoda et al (13). H&E, hematoxylin and eosin; US, ultrasound; BL, bubble liposome; GFP, green fluorescence protein.
Mentions: Gene transfer provides a novel approach for the treatment of retinal diseases. Li et al (57) demonstrated that UTMD was able to safely and effectively deliver plasmids into RGCs in vitro. Under the optimum parameters, the average transfection rate of p enhanced (E)GFP-N1 with UTMD was 25%. Compared with the ultrasound plus plasmid group, the number of transfected cells increased by 28-fold. Another study reported that UTMD-mediated gene transfer of pigment epithelium-derived factor (PEDF) into retina and chorioids of rats inhibited the development of CNV (58). The study also demonstrated that in the short term (7 and 14 days after transfection), the transfection efficiency mediated by UTMD was not different from that achieved by liposome-based gene transfer. However, in the long term (28 days after transfection), the transfection efficiency by UTMD was significantly higher as compared with that of the liposome approach. The shock wave of UTMD promoted the delivery of the plasmid into the cell nucleus, which may partly be explained by the induction of tight binding of the target plasmid to the cell's endogenous DNA. UTMD therefore presents a solution for local gene transfection and reduces the amount of plasmid required. Sonoda et al (13) used a miniature ultrasound transducer to evaluate the efficacy of intravitreal ultrasound (SonoPore 4000) irradiation for selective GFP plasmid transfer into the rabbit retina. The ultrasound probe, as small as a 19-gauge needle, was inserted into the vitreous cavity through a scleral incision. The gene-transfer efficiency was quantified by counting the number of GFP-positive cells. The study demonstrated that the retinas that received plasmid with BL and ultrasound showed a significant increase in the number of GFP-positive cells without any apparent tissue damage (Fig. 3) (13). GFP-positive cells were observed exclusively in the area that was exposed to ultrasound, and no GFP-positive cells were observed in the control eyes that were not treated with ultrasound. These results indicated that gene delivery to the retina using intravitreal ultrasound exposure is more selective than the transcorneal method.

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