Sorter weeds out dud sperm cells

DNA damage increases the risk of infertility

Scientists have developed a machine to separate out healthy sperm from that which is damaged and unlikely to be of use in IVF.

The shoebox-sized device is based on the principle that the sperm with the most negatively charged membranes are likely to have the least DNA damage.

It filters out sperm with a type of DNA damage linked to infertility and a raised risk of childhood cancers.

Details of the Australian invention are published by New Scientist magazine.

If it works, this device sounds like a nice idea. Professor Ian Craft

The developers say the DNA damage the device is designed to weed out is particularly associated with older fathers, heavy smokers and people who have been exposed to pollution in the workplace.

At present, fertility clinics centrifuge semen to increase the concentration of the densest sperm and raise the odds of fertilising an egg.

But it is a time-consuming process and does not identify damaged sperm. It also subjects sperm to a degree of stress.

Voltage

The new machine, called Gradiflow, has been developed by Professor John Aitken and Chris Ainsworth of the University of Newcastle in New South Wales and its commercial partner Life Therapeutics of Sydney.

It consists of two chambers separated by a filter. After the sperm is injected into the first chamber a voltage is applied across the filter to move sperm to the second chamber.

In preliminary tests, using semen from medical students, the 20% of sperm that made it into the second chamber had only half as much DNA damage as the sperm left behind.

Other tests suggest it also works well when sorting the semen of men with fertility problems.

It will be further tested in two clinical trials of women undergoing IVF in Australia later this year.

Dr Moira O'Bryan, of the Monash Institute of Reproduction and Development in Melbourne, told New Scientist: "It is so simple.

"I've never seen anything like it before. You turn it on, the sperm move across and there you go.

"Only time will tell, but it might take some of the subjective nature out of picking good sperm."

Professor Ian Craft, director of the London Fertility Centre, said there was evidence to suggest that DNA damage - or fragmentation - was linked both to a lower IVF success rate, and a higher risk of miscarriage.

"If it works, this device sounds like a nice idea," he said.