Fans of the film Blade Runner may remember a scene in which the maker of an artificial snake is identified by a microscopic serial number on one of its scales. Well, in a rare case of present-day technology actually surpassing that predicted in a movie, we’ve now gone one better – bar codes on embryos. Scientists from Spain’s Universitat Autònoma de Barcelona (UAB), along with colleagues from the Spanish National Research Council, have successfully developed an identification system in which mouse embryos and oocytes (egg cells) are physically tagged with microscopic silicon bar code labels. They expect to try it out on human embryos and oocytes soon.
The purpose of the system is to streamline in vitro fertilization and embryo transfer procedures. If egg cells and embryos can be quickly and easily identified, then things should run much smoother, and success rates should be higher.
The labels, which had been declared biologically innocuous in an earlier study, are microinjected into the perivitelline space of mouse embryos – the perivitelline space is a region between the cell membrane and the zona pellucida, which is a cover that surrounds the embryo’s plasma membrane. The embryo exits the zona pellucida before entering the uterus, so the bar code would be shed at that point.
In the UAB lab studies, labeled embryos were shown to develop normally up until the blastocyst stage, which precedes implantation. The researchers also studied how well the labels stayed on throughout the development cycle, how easily they could be read with a standard microscope, how they could be eliminated after the shedding of the zona pellucida, and how well they could stand up to the freezing and thawing of their host embryo.
There were some problems with embryos being able to free themselves from the labels when they shed the zona pellucida. The scientists are therefore now looking at modifying the surface of the labels, so they could be mounted on the outside of the covering, instead of being injected into the perivitelline space. They are also working on an automated bar code reading system.
Permission has been given by the Government of Catalonia’s Department of Health for UAB to begin testing its system with human oocytes and embryos from several fertility clinics in Spain.
The research was recently published in the journal Human Reproduction.