Genetic diseases might one day be treated by adding an entirely new chromosome to people’s cells. A Canadian company has shown the approach could be a feasible method of gene therapy.

Conventional gene therapy relies on modified viruses to insert the desired bit of DNA into a cell’s genome. But viruses can carry only short sequences of DNA. And if the DNA lands in the wrong place, as happened to two boys in a French gene therapy trial, it can trigger cancer.



Adding an entirely separate chromosome, however, eliminates this risk. And rather than being limited to one or two small genes, vast chunks of DNA can be added if desired.



“For certain diseases it could be very useful to have the ability to deliver multiple therapeutic genes,” says Gil Van Bokkelen, chief executive of Athersys in Cleveland, Ohio, one of several teams worldwide trying to develop artificial chromosomes.



Most, like Athersys, are trying to create artificial chromosomes from scratch. Chromos Molecular Systems of Burnaby, British Columbia, has taken a different approach, creating its artificial chromosome by building it up from the key elements of a normal mouse chromosome.



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