In future a new method could help some couples who are childless against their will. The microscopic procedure significantly improves the success rate of 'ICSI' (intracytoplasmic sperm injection). This was discovered by scientists at the University of Bonn together with colleagues from China and industrial partners in a study of 124 women. Up to now, the desire to have a child is only fulfilled for every third couple that decides to have ICSI. In a study the artificial insemination method was twice as successful. The scientists have now published their data in the journal 'Reproductive BioMedicine'. (Online version available at http://www.rbmonline.com/Article/3161).
Improvements in artificial insemination technology are going to eventually move into the mainstream when genetic testing starts providing a big advantage for those who choose to start pregnancies with IVF. So you might think an advance like this one only applies to the small minority with fertility problems. But in fact this technique or others like it will eventually get used to start a large fraction of all pregnancies in developed nations.
In cases where they can identify 2 promising ova they can achieve a 50% success rate.
Which of the fertilised ova are finally implanted has usually been left up to chance. But today it is known that not all ova have the same quality. Using a special procedure the Bonn scientists can select the two most suitable candidates. 'For this we observe the ovule integument under a DIC microscope,' Dr. Montag explains. 'There it appears as a luminescent orange-red ring. The brighter this ring is and the more uniformly it shines, the greater the chance that it becomes a child.' The reason for this is that the ovule integument always seems to have a particularly uniform structure if the cell has matured under good conditions.
Normally every third ICSI is successful. But if medics used two 'good ' ova in their experiment, this rate increased to more than 50 per cent. With a 'good' and a 'bad' ovum the success rate was still around 40 per cent, using two 'bad' ones only 20 per cent. 'Mind you, two “good” ova are rare,' Markus Montag emphasises. 'Only with two out of ten cells does the ovule integument have an intense regular orange colour.'
If only 2 out of 10 IVF ova look good by this criteria that makes genetically-based embyro selection harder to do. Ideally one would want to be able to choose among dozens of genetically tested and viable embryos. The more you can choose between the closer you can get to your ideal combination of genes that you'll want to pass along to offspring.
To make selection of offspring by genetic testing viable we still need a few more pieces of biotechnology. First off, we need lots of information about what all the genetic variations mean. That information is now coming in a rapidly increasing torrent. Five years from now we are going to know about hundreds or thousands of genetic variations that contribute to health, size, musculature, coordination, personality, intelligence, endurance, and other characteristics. Second, we need the ability to test for thousands of genetic variations in a cell removed from an embryo. Well, the cost of testing for those genetic variations in cells removed from embryos will continue to fall rapidly. So that's not going to be an obstacle for much longer.
Our third and hard problem: The limited number of good ova. You can't test what you don't have. You can only choose among the viable fertilized embryos that can survive and develop into a baby. To solve this problem we probably need the ability to turn adult cells into eggs. Just turning adult cells into eggs isn't enough. The eggs also need all the regulatory state (called epigenetic state). They need the right genes activated and deactivated.
How long will it take to solve the problem of how to mass produce human eggs with correct epigenetic state from adult cells? Once that problem gets solved the rate of human evolution will accelerate by orders of magnitude.
|Share |||Randall Parker, 2008 February 16 12:45 PM Biotech Reproduction|