A recent development in the laboratory at PFC is the acquisition of a laser for use in key procedures. The laser will be used to assist in the processes of Assisted Hatching (AH), Intracytoplasmic Sperm Injection (ICSI), and Pre-implantation Genetic Diagnosis/Screening (PGD/PGS).

All of these procedures require us to make a small opening in the outside shell of the egg called the Zona Pellucida (zona). Prior to laser technology this opening was made with an Acidified Solution, which would slowly dissolve away part of the zona until a small opening was achieved. Now with the laser, a beam of light creates a precise opening in the zona.

Laser use for PGD: The red “pilot light” marks target for the laser. The white circle marks a “safe zone”. The laser is usually fired 3 times for assisted hatching and 5 times for PGD embryo biopsy.

The zona pellucida is a non-living, but important part of the egg. It specifically allows only 1 sperm through to fertilize the egg, and then immediately hardens, preventing other sperm from getting in. After fertilization, the egg divides into 2 cells, and then these divide again into 4 cells. As the embryo continues through these rounds of cell division, the zona keeps all the cells together, since it encloses the embryo. After 5 or 6 days, the embryo has enough cells to begin forming a placenta and the embryo hatches from the zona and attempts to implant in the uterine lining.

Assisted hatching (AH) is a procedure that has been around for about 15 years and it is something that is often performed in the laboratory just prior to an embryo transfer procedure. It is a simple and precautionary procedure where we create a small hole in the zona just before transferring embryos to the uterus. Since the zona is not a living part of the embryo, making a hole does no harm, and in fact facilitates the embryo in hatching from the zona once it’s in the uterus. A normal embryo should be able to hatch all by itself, but in some patients we perform this procedure just to make sure a problem doesn’t arise when the embryo tries to escape from its shell. For AH, the laser will allow us to refine the procedure considerably. Firstly, we will be able to make a hole of an exact size, and secondly, the procedure will be performed more quickly and we will therefore further reduce the amount of time that an embryo is being handled. Traditionally, AH takes about 5 minutes per embryo, but with the laser this time will be reduced to less than a minute. For the process of embryo biopsy for PGD/PGS, an extremely precise opening is made in the zona to facilitate the removal of one cell. Again, the laser will speed the procedure up considerably and reduce the time that we’re working on each embryo.

By now you might be wondering if there are any harmful effects of using laser light on embryos. According to several studies and expert opinions, laser-assisted hatching is superior to chemical-assisted hatching as seen by improved development of “hatched” embryos to the blastocyst stage (the stage at which an embryo will implant in the lining of the uterus). Furthermore, laser-assisted biopsy of cells from embryos for PGD analysis does not appear to have a detrimental effect on the continued development of the embryos versus embryos not undergoing any biopsy procedures. This indicates that using a laser to do the biopsy procedure appears to be safe.

Current lasers have several built-in safety features. The laser system is equipped with a second non-laser beam of light, similar to a penlight, which allows the embryologist to observe where an opening of the zona would be created prior to firing the laser. Also, the temperature that the embryo is exposed to is controlled by the use of Isotherm rings. Isotherm rings help the embryologist prevent potential harmful thermal effects on cells adjacent to the zona due to heat from the laser beam. The rings indicate both the drill hole size and the safety region based on temperature. With this interactive feature, the user can predetermine the hole size and eliminate practically all risk of impacting cells within the embryo.

PFC’s new laser system has been tested for both accuracy and precision. In addition, the lab staff is undergoing training with Laser professionals on its use and maintenance. They will have unlimited practice time, ensuring the highest level of safety and technique when it comes time to use it on human embryos.

– Jean M. Popwell, PhD TS (AB, PFC Lab Embryologist)

Tags: Genetic Testing, IVF - In Vitro Fertilization, Lab, New Innovation, PGD - Preimplantation Genetic Diagnosis, PGS - Preimplantation Genetic Screening, What's New @ PFC?

This entry was posted on Sunday, June 20th, 2004 at 2:21 pm and is filed under From Us To You. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.