Body Language

By | April 4, 2005
3 Comments

A team led by scientists at Sangamo Biosciences in Richmond, California has reported in the journal Nature that they have developed a sophisticated new process for editing DNA without bombarding the genome with foreign genetic material.

They treated the cells in test tubes with the company’s proprietary type of “zinc finger nucleases” (ZFNs)… ZFNs are proteins made up of “fingers” of around 30 amino acids and stabilised by a zinc atom. Each finger binds to a specific combination of DNA bases and is attached to a DNA-cutting enzyme called a nuclease.

By using different combinations of amino acids, they can be designed to latch on to DNA at exactly the place where the mutated gene lies and cut it. This triggers the body’s natural repair process, called homologous recombination, which corrects the gene where the DNA was cut, The researchers provided the cells with a copy of the correct gene as a template.

This could be the beginning of a huge step forward. Previous forms of genetic therapy often caused cancer. Scientists would bombard the genome with the desired information and hope it stuck in the right place. It’s like blindly lobbing paint balloons at a road sign hoping to cover graffiti without obscuring the speed limit. Sometimes it worked, often it didn’t.

This new method is more like word processing. These scientists are hopeful that this advance will yield useful therapies for single gene mutations like that which causes sickle cell anemia or the “bubble boy” disease.

This new method might ultimately have applications beyond treating genetic diseases. Recently Phil and I have been speculating about the possibility of biological cyborgs. These people would remain largely biological, but would have an implanted processor for directing the work of biological nanobots. These “nanobots” might be our own cells redirected as the processor sees fit – cleaning up arteries, compensating for poor eating habits, etc. Obviously such a system would need a sophisticated method for communicating with cells. It would have to speak the language of cells.

A DNA “word processor” might fit the bill.

UPDATE: USAToday has much more. Via KurzweilAI.

  • https://www.blog.speculist.com Phil Bowermaster

    I wonder what other tricks we could do with a genetic word processor. Could I change my eye color? Could I make myself “naturally” thin?

  • https://www.blog.speculist.com Stephen Gordon

    Phil:

    Your question brings to mind something I’ve wondered about. If a person has a disease caused by a genetic mutation, how do you correct all (or enough of) the typos?

    With a mutation that occurred at conception every single cell in the body would have a bad copy. Presumably you would not have to correct every cell in the body to improve a bubble boy’s immune system, but how much is enough, and how as a practical matter do you do this? This is a question not just for exotic genetic therapy but also the crude therapy currently used. How is one corrected cell enough? And when that cell dies and is replaced by another, wouldn’t the replacement have a bad copy?

    To change eye color I presume we’d only have to change some cells in the eye, not the whole body. Maybe you could administer that “cut and paste” correction with eye drops. How about blond gene shampoo?

  • Engineer-Poet

    IIRC, children with the “bubble boy” mutation (Severe Combined Immune Deficiency) have been cured by injection of corrected genes into bone marrow stem cells and re-implantation of the modified cells; the “fixed” stem cells appear to out-compete and replace the defective originals.  In this case, alteration of all or even many cells in the body is not required; even a small fraction will do.

    What fraction of the body’s cells would have to be modified to correct Duchenne’s Muscular Dystrophy or hypercholesteremia?  I don’t know, but it would be interesting to find out.