Selection of DNA fragmentation negative motile sperm and high precision insemination using artificial fallopian tubes

Intracytoplasmic sperm injection (ICSI) is rapidly becoming the last resort for severe cases of male infertility. Currently, about 5 per cent of new-borns in Japan are the result of assisted reproductive technology (ART), and about 80 per cent of these fertilisations are performed with the aid of ICSI. However, this method merely compensates for deficiencies in sperm number, and not for functional deterioration.

To truly distinguish viable sperm candidates for infertility treatment as intact DNA or those who have already undergone the early stages of DNA fragmentation and deterioration, Dr Kaneko developed an innovative, new method: single-cell pulsed-field gel electrogenesis (SCPFGE). 'Firstly, the technique purifies motile sperm using the combination of density gradient centrifugations with different principals,' Dr Kaneko notes. 'The sperm is then embedded in a thin film of agarose that is subsequently broken down.' By the end of the process, elongated DNA fibres of the purified motile sperm are rendered visible, and in some cases, DNA fragments were present, gathered at the ends of these fibres, numbers and sizes varying among the sperm. 'SCPFGE revealed that merely selecting motile sperm under a microscope, the typical procedure for ICSI, would not guarantee the integrity of DNA,' observes Dr Kaneko. A portion had already begun to exhibit the early stages of DNA fragmentation. The data suggests that medical staff should obey more thorough parameters for choosing injected sperm in ICSI. However, after undergoing SCPFGE examination or an invasive staining process to expose vacuoles, sperm cannot not be used for treatment. Currently, selecting motile sperm from under the microscope is the only option. While further research is needed to overcome this challenge, SCPFGE and other examination techniques can be carried out to reveal quality of sperm. If a patient wishes to undergo ICSI, SCPFGE can inform them if the process is worthwhile. If most of their motile sperm exhibits fragmented DNA, there is good chance ICSI will not work for them. Through studying ICSI in such depth, Dr Kaneko has introduced a new term – intracytoplasmic qualified sperm injection (IQSI), referring to the injection of sperm determined to exhibit DNA integrity, or In-ICSI.