Gene Therapy Cures "Bubble Boy"

bofh31337 writes "NewScientist is reporting that Welsh boy Rhys Evans has been cured of the fatal severe combined immunodeficiency ("bubble boy") disease. The medical team, lead by Adrian Thrasher, was able to take the stem cells that give rise to immune cells from his bone marrow and add a normal copy of the gene to the stem cell using a retro virus. Seven months after treatment, Rhys was cured."

Comments

More coverage...

[abhinavnath]

The Guardian, and Yahoo

Re:More coverage...

[red_gnom]

And also:

Gene therapy

Cystic Fibrosis Gene Therapy

Re:Question

[glwtta]

The laws don't restrict the research itself, they restict the number of cell lines available for research. So yeah, it would've been possible in the US, provided the scientists could get their hands on the stem cells.

Re:Question

[ageitgey]

The US has laws limiting embryonic stem cell research. They don't care if use use cells from yourself (as they did with the 'bubble boy'). The issue is whether or not more break-throughs of this type could be made faster by using stem cells from all the frozen embroyos laying around (which are basically big clumps of stem cell :)

gene therapy

[borg]

The biggest problem with gene therapy is that long term expression of the target gene has been difficult to achieve. The inserted sequence, depending on the gene carrier, may or may not be inserted in to host genome. Actual insertion into the host genome is undesirable because of possible malignant transformation (insertion of the target sequence disrupts the function of a tumor supressor protein, or turns on a pro-tumor protein, etc.). Existing as a genetic sequence outside of the genome proper has also failed to achieve more than temporary expression of the desired protein.

This article describes a technique to increase the effiency of the transfer of a therapeutic gene sequence into a target cell. It does nothing to address the biggest stumbling block of gene therapy. While this is sexycool news, being cured for 3 or 7 months doesn't mean being cured for life.

Claimer: IAAMD
I don't mean to be a downer. We're just a loooong way off from real gene therapy.

retrovirus information

[jest3r]

A retrovirus is special because it contains an enzyme called reverse transcriptase. This enzyme works backwards, translating RNA into DNA. Retroviruses contain RNA within their protein coat, and use reverse transcriptase to create DNA that can be inserted into the cell it is attacking. One of the most famous (or perhaps infamous) retroviruses is the HIV retrovirus, which causes AIDS.

Retroviruses are being investigated for 3 reasons:

1) They can be used as vectors to transport genetic information into a host cell.

2) Reverse transcriptase can be used to isolate DNA sequences from a mRNA chain so that the gene can be manipulated through bioengineering techniques.

3) To find a way to genetically engineer a cure for AIDS. If the action of reverse transcriptase can be halted somehow, the HIV virus will have no way to spread its harm through the body and millions of lives could be saved.

more info

Re:Question

[nathanm]

The laws don't restrict the research itself, they restict the number of cell lines available for research.

They don't actually restrict the number of stem cell lines, they merely limit government funding to the existing lines. Anyone could start new lines with private funding.

Also, the policy only refers to embryonic stem cells. The bubble boys were cured with their own stem cells.

Re:X chromosomes

[PlatinumMac]

No, everyone has 44 autosomal chromosomes and 2 sex chromosomes (either one X and one Y or two Xs).

X chromosomes are distinctly different from the autosomal chromosomes. No human being can live with a missing autosomal chromosome (e.g. only one chromosome 21 instead of two) -- embryos with this type of defect are miscarried so early that they are not even detected, even though embryos with three copies of an autosomal chromosome (a defect arising from the same mistake in meiosis which causes the loss of an autosomal chromosome in some embryos) are detected -- some even live to adulthood (Down syndrome). On the other hand, all human beings can be said (in general) to have only one X chromosome; in females, one X chromosome is almost completely inactivated in each cell.

Other issues

[nucal]

A few reasons why this worked so well:

• This form of SCID is due to a total gene deletion - so that gene replacement was feasible. A lot of genetic diseases are due to genes expressing proteins that are mutated, but still produced. These mutant proteins can frequently have a dominant negative effect, that is, they mess up normal copies of the protein or other proteins in the cell. In this case, adding more good copies of the gene in question will not help.
• Being able to treat stem cells in isolation is a big advantage, since you don't have to target cells in the context of the whole body (needle in haystack problem). In culture, the virus to cell ratio can be really high, increasing the probability of successful infection. Also, stem cells successfully expressing the gene of interest can be selected and preferentially propagated in culture before re-introducing into the patient.
• Another big advantage in being able to treat isolated cells is that you avoid the potential problem of an immune response to the virus itself. This was a big problem recently with a different class of viruses. In some ways SCID, being an immune deficiency, is the ideal disease for viral gene therapy, since these patients are less likely to react to the virus itself.

Re:How about AIDS?

[Steve B]

Nope -- see the Straight Dope column answering that question.