Tiny capsules offer alternative to viral delivery of gene therapy


tinycapsules
A graphic description of the nanocapsule delivery system. Credit: UW-Madison

New tools for editing genetic code offer hope for new treatments for inherited diseases, some cancers, and even stubborn viral infections. But the typical method for delivering gene therapies to specific tissues in the body can be complicated and may cause troubling side effects.

Researchers at the University of Wisconsin-Madison have addressed many of those problems by packing a gene-editing payload into a tiny customizable, synthetic . They described the  and its cargo today (Sept. 9, 2019) in the journal Nature Nanotechnology.

“In order to edit a gene in a cell, the editing tool needs to be delivered inside the cell safely and efficiently,” says Shaoqin “Sarah” Gong, a professor of biomedical engineering and investigator at the Wisconsin Institute for Discovery at UW-Madison. Her lab specializes in designing and building nanoscale delivery systems for targeted therapy.

“Editing the wrong tissue in the body after injecting gene therapies is of grave concern,” says Krishanu Saha, also a UW-Madison biomedical engineering professor and steering committee co-chair for a nationwide consortium on genome editing with $190 million in support from the National Institutes of Health. “If  are inadvertently edited, then the patient would pass on the gene edits to their children and every subsequent generation.”

Most genome editing is done with , according to Gong. Viruses have billions of years of experience invading cells and co-opting the cell’s own machinery to make new copies of the virus. In gene therapy, viruses can be altered to carry genome-editing machinery rather than their own viral  into cells. The editing machinery can then alter the cell’s DNA to, say, correct a problem in the genetic code that causes or contributes to disease.

“Viral vectors are attractive because they can be very efficient, but they are also associated with a number of safety concerns including undesirable immune responses,” says Gong.

New cell targets can also require laborious alterations of viral vectors, and manufacturing tailored viral vectors can be complicated.

“It is very difficult—if not impossible—to customize many viral vectors for delivery to a specific cell or tissue in the body,” Saha says.

Gong’s lab coated a  payload—namely, a version of the gene-editing tool CRISPR-Cas9 with guide RNA designed in Saha’s lab—with a thin polymer shell, resulting in a capsule about 25 nanometers in diameter. The surface of the nanocapsule can be decorated with functional groups such as peptides which give the nanoparticles the ability to target certain .

The nanocapsule stays intact outside cells—in the bloodstream, for example—only to fall apart inside the target cell when triggered by a molecule called glutathione. The freed payload then moves to the nucleus to edit the cell’s DNA. The nanocapsules are expected to reduce unplanned genetic edits due to their short lifespan inside a cell’s cytoplasm.

This project is a collaboration combining UW-Madison expertise in chemistry, engineering, biology and medicine. Pediatrics and ophthalmology professor Bikash R. Pattnaik and comparative biosciences professor Masatoshi Suzuki and their teams worked to demonstrate gene editing in mouse eyes and skeletal muscles, respectively, using the nanocapsules.

Because the nanocapsules can be freeze-dried, they can be conveniently purified, stored, and transported as a powder, while providing flexibility for dosage control. The researchers, with the Wisconsin Alumni Research Foundation, have a patent pending on the nanoparticles.

“The , superior stability, versatility in surface modification, and high editing efficiency of the nanocapsules make them a promising platform for many types of gene therapies,” says Gong.

The team aims to further optimize the nanocapsules in ongoing research for efficient editing in the brain and the eye.


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Lipid Nanoparticles Ideal For Delivering Drugs


QDOTS imagesCAKXSY1K 8A research team from the Faculty of Pharmacy of the Basque Public University(UPV/EHU) – Spain – is using nanotechnology to develop new formulations that can be applied to drugs and gene therapy. Specifically, they are using nanoparticles to design systems for delivering genes and drugs; this helps to get the genes and drugs to the point of action so that they can produce the desired effect. The scientists have shown that lipid nanoparticles are ideal for acting as vectors in gene therapy. Gene therapy is a highly promising alternative for diseases that so far have no effective treatment. It consists of delivering a nucleic acid, for example, a therapeutic gene, to modulate the expression of a protein that is found to be altered in a specific disease, thus reversing the biological disorder.

lipid-nanoparticle

“Using lipid nanoparticles conducts to  new formulations to deliver drugs that are not particularly soluble or which are difficult to absorb”, Dr Rodriguez explained. “40% of the new pharmacologically active molecules are reckoned to be insoluble or not very soluble in water; that prevents many of these potentially active molecules from ever reaching the clinic because of the problems involved in developing a safe, effective formulation.” explains Dr Alicia Rodriguez.

Researchers show that lipid nanoparticles are ideal for delivering genes and drugs

At the Faculty of Pharmacy of the Basque Public University (UPV/EHU) the Pharmacokinetics, Nanotechnology and Gene Therapy research team is using nanotechnology to develop new formulations that can be applied to drugs and gene therapy.Specifically, they are using nanoparticles todesignsystems for delivering genes and drugs; this helps to get the genes and drugs tothe point of action so that they can produce the desired effect.

The research team has shown that lipid nanoparticles, which they have been working on for several years, are ideal for acting as vectors in gene therapy.Gene therapy is a highly promising alternative for diseases that so far have no effective treatment.It consists of delivering a nucleic acid, for example, a therapeutic gene, to modulate the expression of a protein that is found to be altered in a specific disease, thus reversing the biological disorder.

The main obstacle is that the genetic material cannot be formulated in conventional pharmaceutical ways, because it becomes degraded within the organism and cannot perform its function.To overcome this obstacle, viral vectors are normally used and they are able to deliver the therapeutic gene to the cells in which it has to act.However, as Dr Alicia Rodriguez explains, “viral vectors have a great drawback because they have a great potential to develop tumours.That is why there is a lot of interest in developing non-viral vectors, like vectors based on lipid nanoparticles.”

“In this respect,” adds Dr Rodriguez, “we have for several years been working to develop formulations for treating degenerative retina diseases, diseases for which there is currently no effective curative or palliative treatment and which causes blindness in the patients who in many cases are very young people.”The research they have done has borne fruit already, and they have in fact managed to develop a vector capable of making a protein express itself in the eyes of rats after ocular delivery.The work has produced two patents and various papers published in top scientific journals, like Human Gene Therapy.

Aim:to improve drug absorption

Another application of lipid nanoparticles is to develop new formulations to deliver drugs that are not particularly soluble or which are difficult to absorb.Dr Rodriguez explained the problem with these drugs:“40% of the new pharmacologically active molecules are reckoned to be insoluble or not very soluble in water; that prevents many of these potentially active molecules from ever reaching the clinic because of the problems involved in developing a safe, effective formulation.”

The Faculty of Pharmacy’s research team has shown that the strategy of encapsulating drugs of this type in lipid nanoparticles is effective:“They are spheres made of lipids and they have very small particleswhich encase the drug.That way, the absorption of the drug given orally can be increased,” points out Dr Rodriguez.

Part of the research was done in collaboration with the research team led by DrVéroniquePréat, of the Catholic University of Louvain in Belgium.There they studied the capacity of the nanoparticles to pass through the intestinal barrier and therefore increase the permeability of the drug.The results of this work have been published in the Journal of Controlled Release, a leading journal within the specialty.

Furthermore, while considerable advances have been made in both areas (vectors for gene therapy and improvement in insoluble drug absorption), the researchers in the Pharmacokinetics, Nanotechnology and Gene Therapy team are working in a third area linked to hepatitis C in which they also hope to achieve positive results.