Scientists from the Małopolska Centre of Biotechnology at the Jagiellonian University in the southern city of Kraków and the Polish Academy of Sciences' Institute of Nuclear Physics say they are the first in the world to use holotomography, a laser technique used to create three-dimensional images of microscopic objects, to assess living egg cells in three dimensions.
The method allows researchers to examine the distribution of fats, or lipids, inside an egg cell.
The team believes this can help embryologists to select eggs with the best prospects for healthy development before they are fertilized.
The researchers cite an average success rate for IVF of about 35 percent, or roughly three treatment cycles for one birth.
Clinics therefore typically collect and fertilize several eggs, producing embryos that can be transferred in successive attempts.
The Polish team hopes more accurate egg selection could increase the proportion of successful pregnancies while allowing clinics to fertilize fewer eggs and create fewer surplus embryos.
During IVF treatment, hormonal stimulation causes several eggs to mature at the same time. Doctors may collect anything from a few to several dozen mature egg cells, or oocytes, but conventional microscopy provides limited information about which are most likely to develop successfully.
"Under a light microscope, all the egg cells collected by the doctor look more or less the same," said Grażyna Ptak, a professor at the Jagiellonian University.
Holotomography is a form of optical microscopy that uses differences in the way light passes through substances such as fat and water to construct a three-dimensional image.
"Holotomography allows us to see a living cell in three dimensions without using any markers," said Joanna Depciuch-Czarny of the Institute of Nuclear Physics, who helped develop the technology.
The examination takes about 10 minutes and does not require dyes or other substances to be introduced into the cell.
Ptak's team has focused on lipid droplets, structures that store energy and signaling molecules and can also collect toxic products of oxidation when a cell is under stress.
"When we see large lipid droplets, it is a signal that the cell is of lower quality," Ptak said.
In animal studies, the researchers found a strong correlation between abnormal lipid profiles in egg cells and abnormalities in the embryos, fetuses and adult offspring that developed from them.
Similar lipid changes persisted in subsequent generations of mice.
Applying holotomography to egg cells presented a technical problem. The technique had previously been used mainly to examine smaller cells attached to a surface.
An egg cell is much larger, spherical and suspended in culture medium, making it difficult to keep still while it is scanned.
The team developed a method to immobilize and image a single suspended oocyte, an approach included in its patent application.
Researchers are now developing artificial intelligence software to analyze the resulting images and automatically identify abnormal cells.
Ptak said the software component should be ready within several months. The team would then need to work with holotomographic microscope manufacturers to adapt equipment for use in fertility clinics.
Ptak said the aim was to give embryologists a practical way to select eggs with normal lipid profiles before fertilization.
"If we precisely identify the best cells, clinics and assisted reproduction centers could fertilize, for example, just two selected egg cells instead of 10," she said.
(rt/gs)
Source: naukawpolsce.pl