‘Spermbots’ successful in proof-of-concept fertility studies.

Semen quality is a measure of the ability of semen to accomplish fertilization and a measure of fertility in a man. It is the sperm in the semen that are of importance, and therefore semen quality involves both sperm quantity and quality. Decreased semen quality is a major factor of male infertility.  Despite advances in fertility treatment, poor semen quality, particularly abnormally low motility of spermatozoa, is still a problem.  Now, researchers at IFW Dresden have developed motorized ‘spermbots’, in a proof-of-concept study, that can deliver healthy sperm with low motility to an egg. The study is published in the journal Nano Letters.

Previous studies show that sperm that don’t swim well rank high among the main causes of male infertility.  To give these cells a boost, women trying to conceive can turn to artificial insemination or other assisted reproduction techniques.  Artificial insemination is a relatively inexpensive and simple technique that involves introducing sperm to a woman’s uterus with a medical instrument; overall, the success rate is on average under 30%. In vitro fertilization can be more effective, however it’s a complicated and expensive process. It requires removing eggs from a woman’s ovaries with a needle, fertilizing them outside the body and then transferring the embryos to her uterus or a surrogate’s a few days later; success can be elusive in both techniques.  The current study presents artificially motorized sperm cells, where customized microhelices serve as motors for transporting sperm cells with low motility to help them carry out their natural function.

The current study utilised tiny metal helices just large enough to fit around the tail of a sperm, whose movements can be controlled by a rotating magnetic field. Results show that the motors can be directed to slip around a sperm cell, drive it to an egg for potential fertilization and then release it.  Data findings show that metal-coated polymer helices are suitable for this task due to potent, controllable, and nonharmful 3D motion behavior. They go on to note that important steps toward fertilization are addressed by employing proper means of sperm selection and oocyte culturing.  The researchers also provide video imaging of the spermbots in action.

The team surmise that they were able to capture, transport, and release single immotile live sperm cells in fluidic channels that mimick physiological conditions.  For the future, the researchers state that although much more work needs to be done before their technique can reach clinical testing, the success of their initial demonstration is a promising start.

Source: American Chemical Society