Forum for Science, Industry and Business

Gene taxi with turbo drive

Parkinson's disease, Huntington's disease, cystic fibrosis – these and many other fatal hereditary human diseases are genetically transmitted. Many cancers and cardiovascular diseases are also caused by genetic defects. Gene therapy is a promising possibility for the treatment of these diseases. With the help of genetically modified viruses, DNA is introduced into cells in order to repair or replace defective genes.

After infection with CD9-containing viruses, human HEK293 cells produce a red fluorescent reporter protein that indicates the successful transmission of viral genetic information into the cells.

Photo: Kai Böker

Dr. Jens Gruber is head of the Junior Research Group Medical RNA Biology at the German Primate Center.

Photo: Christian Kiel

By using this method, scientists from the German Primate Center (DPZ) – Leibniz Institute for Primate Research have discovered a quicker and more efficient treatment for the cells. For this purpose, the scientists changed the so-called HEK293 cell line that is used for the production of therapeutic viruses. The cells then produced a protein called CD9 in large quantities.

In addition, they modified the viruses used for gene transfer in such a way that CD9 is integrated into their envelope membrane. These genetic manipulations resulted in a faster and more efficient infection of the target cells. The resulting higher transfer rate of DNA into the target cells promises new and improved gene therapy treatment. The study was published in the journal Molecular Therapy.

The ability of viruses to introduce their genetic material into the host cells is used as a tool in gene therapy. These "gene taxis" consist of modified viruses, the so-called viral vectors. They are equipped with fully functional genes to replace the defective disease-causing genes in the cells. However, the prerequisite for this is that the viruses recognize and infect the corresponding cells. This is the point where the research of the junior research group Medical RNA Biology at the German Primate Center comes in.

Transport bubbles in the cell should increase the efficiency of gene therapy

“In our study, we wanted to find out if it was possible to improve the infection rate of viral vectors and how,” says Jens Gruber, head of the junior research group and senior author of the study. “At the moment, the infection rates, depending on the target cells, are often around 20 percent, which is not enough for certain therapies.”

To change that, the researchers looked at the production of the so-called exosomes to find out how to use this mechanism in order for the virus vectors to become more efficient. Exosomes are small membrane vesicles filled with proteins, RNA or other molecules. They are used for the transportation of cell components and for intercellular communication. “Our hypothesis was that we could improve the production of viruses and their efficiency by boosting exosome production in the cells,” explains Jens Gruber explaining the relevance of the transport vesicles for the study.

In order to produce large quantities of the CD9 protein, Jens Gruber and his team genetically engineered the HEK293 cell lines that are used for the production of viral vectors. This protein is known for its function in cell movement, cell-cell contact, and membrane fusion. The assumption was that it could also play a role in exosome production. In addition, scientists incorporated the CD9 protein into the envelope membrane of viral vectors. “We were able to observe two things,” Jens Gruber summarizes the results.

“Firstly, in comparison to the untreated HEK293 cells, exosome production in the HEK293-CD9 cells increased significantly, which suggests a crucial role of the protein in exosome formation. Secondly, the incorporation of the CD9 protein in the viral membrane has significantly improved the transfer of DNA. This was observed in an increased number of infected target cells that carried the desired gene without the implementation of additional virus vectors.”

80 percent infection rate

The increased amount of CD9 in the virus resulted in a higher infection rate that amounted to approximately 80 percent. The protein appears to have a direct impact on exosome production and virus efficiency, which has previously not been described. “The results of our study provide us with a better understanding of exosome formation as well as virus production in cells,” says Jens Gruber. “These findings can be used to make currently used virus-based gene therapies more efficient. In future, one might be able to completely abstain from using viruses and only use exosomes to transport genetic material into target cells."

Original publication

Böker KO, Lemus-Diaz N, Rinaldi Ferreira R, Schiller L, Schneider S, Gruber J (2017): The impact of the CD9 tetraspanin on lentivirus infectivity and exosome secretion. Molecular Therapy, 26(2), DOI: http://dx.doi.org/10.1016/j.ymthe.2017.11.008

Contact and notes for editors

Dr. Jens Gruber
Tel.: +49 (0) 551 3851 193
E-Mail: jgruber@dpz.eu

Dr. Sylvia Siersleben (Communication)
Phone: +49 (0) 551 3851 163
Email: ssiersleben@dpz.eu

Weitere Informationen:

http://medien.dpz.eu/webgate/keyword.html?currentContainerId=4241http://www.dpz....

Dr. Susanne Diederich | idw - Informationsdienst Wissenschaft

Im Focus: The coldest reaction

With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction

The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...

Im Focus: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

Im Focus: McMaster researcher warns plastic pollution in Great Lakes growing concern to ecosystem

Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.

In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...

Im Focus: Machine learning microscope adapts lighting to improve diagnosis

Prototype microscope teaches itself the best illumination settings for diagnosing malaria

Im Focus: Small particles, big effects: How graphene nanoparticles improve the resolution of microscopes

Conventional light microscopes cannot distinguish structures when they are separated by a distance smaller than, roughly, the wavelength of light. Superresolution microscopy, developed since the 1980s, lifts this limitation, using fluorescent moieties. Scientists at the Max Planck Institute for Polymer Research have now discovered that graphene nano-molecules can be used to improve this microscopy technique. These graphene nano-molecules offer a number of substantial advantages over the materials previously used, making superresolution microscopy even more versatile.

Microscopy is an important investigation method, in physics, biology, medicine, and many other sciences. However, it has one disadvantage: its resolution is...