Potential gene therapy technique uses artificial chromosomes

Posted Dec 2, 2011 by Albert Baer
In a paper published Nov. 28, genetic researchers describe a potential new method of gene therapy which makes use of artificial human chromosomes.
An image of a newt lung cell stained with fluorescent dyes undergoing mitosis  specifically during e...
An image of a newt lung cell stained with fluorescent dyes undergoing mitosis, specifically during early anaphase. According to NIH, "The scientists use newt lung cells in their studies because these cells are large, easy to see into, and are biochemically similar to human lung cells." The material stained green are the mitotic spindles, the material stained red is the cell membrane and some components of the cytoplasm near it, and the material stained light blue are the chromosomes. Source:Nat
National Institutes of Health
Unlike infectious diseases which are caused by invading agents, like bacteria or viruses, genetic disorders are caused by defects in the patient’s own DNA. In genetic disorders, some segments of DNA contain mutations which prevent the normal, healthy operation of the patient’s cells. Whereas infectious diseases are cured by eliminating the disease agent from the body, genetic disorders are virtually impossible to cure because the source of the problem is the patient’s own genes.
The goal of gene therapy is to insert correct, functional copies of genes into a patient’s cells in order to correct for the defective genes. Now, researchers are investigating a new method of gene therapy making use of artificial chromosomes. The complete human genome is naturally divided into 46 shorter segments called chromosomes. Each chromosome contains many genes, and also has DNA segments and associated proteins that help the cell to access the proper genes on the chromosome, as well as aid in duplicating the chromosome during cell division.
Previous methods of gene therapy have involved inserting new genes into a patient’s natural chromosomes, but this method has presented some difficulties. The new research is looking at adding whole new, artificial chromosomes to patient’s cells. These chromosomes would carry the corrective genes.
The artificial chromosome technique potentially addresses a few issues with the standard gene-insertion techniques. Adding new chromosomes reduces the chance that genes will disrupt other, functional genes when they are inserted into natural chromosomes. According to the researchers, the artificial chromosome technique also overcomes limitations to the lack of control of the number of copies of genes inserted into cells. The researchers also report that the artificial chromosomes are able to be easily deactivated, allowing greater control over the inserted genes’ activity even after they are incorporated into living cells.
The researchers are hopeful that this new study will offer more effective options both for future genetic studies and for clinical applications as a method for better gene therapy techniques.
The research is available in the Proceedings of the National Academy of Sciences.