Selective embryo technique could lead to improved IVF

29 Apr

In a new study published in the journal Biomicrofluidics, researchers from Taiwan reveal the creation of a new technique they say could eventually lead to more effective, cheaper in vitro fertilization for couples struggling to conceive.
Microwell system
The “microwell system” allows embryos to be screened and the most promising ones to be selected for transfer.
Image credit: Chihchen Chen/National Tsing Hua University and the National Health Research Institutes

Around 1 in 8 couples in the US have problems getting pregnant or sustaining a pregnancy. While 85-90% of infertility cases can be treated with standard therapies, such as medication or surgery, in vitro fertilization (IVF) may be an option for others.

IVF is a form of assisted reproductive technology (ART) in which eggs and sperm are combined in test tubes to create embryos, which are then transferred to a woman’s uterus.

While IVF has shown huge success – with almost half of all IVF cycles performed in women aged 35 and under resulting in live births in 2013 – it does have some drawbacks.

In order to have a successful pregnancy, couples undergoing IVF often need multiple cycles. Not only can this take its toll emotionally, it can cause financial pressure; one IVF cycle in the US is estimated to cost around $12,000. This means many infertile couples cannot even afford to have the procedure.

But researchers from National Tsing Hua University and the National Health Research Institutes in Taiwan claim a new technique they have developed could not only reduce the cost of IVF – making the procedure more accessible to infertile couples – it could boost the procedure’s success rates.

‘Microwell system’ allows selection of the most promising embryos

Lead investigator Chihchen Chen and her team explain that their new technique allows each individual embryo to be assessed prior to being transferred into the uterus, meaning the ones with the highest likelihood of success can be selected.

The researchers explain that in IVF, embryos are often “pooled together” in tiny drops of fluid, known as microdrops, before they are implanted in the uterus. While effective for culturing the embryos, the viability of each individual embryo cannot be easily determined.

In their study, Chen and colleagues developed a “microwell system,” which they tested with mouse embryos. The embryos are placed on a dish of tiny open microwells, or holes, before being covered with a layer of oil. The oil stops the embryos from moving from one microwell to another, but a micropipette is still able to penetrate the layer in order to remove the embryos for uterus implantation.

The researchers explain that their microwell system gives each embryo its own environment, meaning the viability of each embryo can be assessed more easily. “Embryos are very sensitive to their environments,” explains Chen. “Understanding the microenvironment of embryos allows us to promote the growth and minimize the epigenetic manipulation of embryos.”

Blastocyst development predicted with new technique

Using high-resolution time-lapse imaging to monitor the development of each embryo, the researchers found that even when cultured in the tiny microwells, the embryos successfully developed into blastocysts – structures that form during early embryonic development.

What is more, the researchers found they were able to predict the embryo’s likelihood of developing into blastocysts by the length of time it took for them to successfully reach the 4-cell and 8-cell stages in the microwells, allowing early-stage embryos to be screened and the most promising ones to be selected for transfer.

The researchers hope it will not be too long before their newly created technique can be used in humans, though Chen notes the experimental conditions need to be optimized for human embryos and clinically validated first.

Chen and colleagues say their targeted approach would reduce the number of eggs needed for IVF, lowering the procedure’s cost and the number of cycles required.

“It will lower the stress level of patients greatly if the number of IVF cycles and embryos transferred can be reduced while maintaining a promising outcome,” she adds.

In January, Medical News Today reported on a study by researchers from the Centers for Disease Control and Prevention (CDC), which claims a form of ART called intracytoplasmic sperm injection (ICSI) is no better than IVF for infertility.