A million, a million exosomes
Researchers from Ohio State University, led by Professor James Lee, have developed a new method of gene therapy based on the transformation of human cells into a source of nanoscale particles with genetic material that can potentially be used for gene therapy. The study was originally conceived to confirm the concept, but in the course of it, an experimental therapy was developed that slows down tumor growth and increases survival in mice with glioma, the most common malignant brain tumor in humans.
Exosomes are fluid–filled bubbles that cells release into the intercellular space and use as a means of removing excess molecules and communicating with other cells.
The researchers saw in exosomes biologically friendly carriers of therapeutic materials, of which there are many and which do not cause an immune reaction. The difficulty lay in the way to put relatively large genetic instructions into exosomes in an amount that would have a therapeutic effect.
The new method is based on a patented technology that forces donor human cells to release millions of exosomes. After collection and purification, they function as nanocarriers containing the drug. When these exosomes enter the bloodstream, they accurately find their target in the body, even if it is in the brain.
In 2017, in the field of regenerative medicine, the technique of "tissue nanotransfection" (TNT) was created, in which a nanochip is used to deliver biological cargo directly into the skin. This action transforms adult cells into any type of cells of interest to researchers for treatment directly in the patient's body. Investigating the mechanism of TNT, scientists from Lee's laboratory found that these exosomes deliver regenerating products to tissues located deep under the surface of the skin. In the new study, the technology was adapted to the technique of cellular nanoporation.
About 1 million donor mesenchymal cells taken from human adipose tissue were placed on a nanoscale silicon wafer and synthetic DNA was injected into them using an electric pulse. As a result of such forced filling, cells must throw out unwanted material in the form of messenger RNA molecules and repair holes that were made in their membranes. Both actions are performed by exosomes. Being the "garbage bag" of the cell, they leave it with the genetic material inside. This is how a biological drug comes out of the cell.
Electrical stimulation has increased the number of exosomes with therapeutic genes thousands of times, which means that the technology is scalable to produce enough nanoparticles for use in humans.
For any gene therapy, it is important to know which genes and where they need to be delivered. The researchers tested the effectiveness of the method for the treatment of glioma in mouse models. The PTEN gene, which is a cancer suppressor, was used as an exosome filling. Mutations in the PTEN gene are known to disable its ability to inhibit the growth of atypical cells, allowing cancer cells to divide uncontrollably.
Synthetic DNA, forcibly injected into donor cells, is copied into a messenger RNA molecule that contains instructions necessary for the production of a specific protein. Each exosomal bubble containing an RNA messenger turns into a nanoparticle ready for transportation.
The advantages of the method are the absence of toxicity, the body's immune response and problems with overcoming the blood-brain barrier. Exosomes are programmed not only to destroy cancer cells, but also to search for them.
Experiments on mice showed that pre-labeled exosomes in large numbers reached brain tumors and slowed their growth, compared with substances used as controls.
Access to the brain will in the future also allow the use of exosomes for the treatment of neurological diseases such as Alzheimer's and Parkinson's disease.
Article Z.Yang et al. Large-scale generation of functional mRNA-encapsulating exosomes via cellular nanoporation is published in the journal Nature Biomedical Engineering.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on Ohio State News: A new gene therapy strategy, courtesy of Mother Nature.