Lasers in the IVF lab
IVF is one of modern medicine’s dramatic success
stories . This is especially because of the phenomenal
advances which have occurred in the IVF laboratory ,
and infertility treatment today is largely based on
our ability to manipulate gametes and embryos in vitro
in the IVF laboratory. However, advances in IVF are
now limited by technical proficiency, which emphasizes
why we need to apply new technology which allows for
greater precision in gamete handling.
Given the fact that eggs, sperms and embryos are all
microscopic, it is hardly surprising that one of the
successful advances in recent times has been the introduction
of lasers in the IVF lab, since lasers allow the embryologist
to deliver a controlled amount of energy at a specified
spot with exquisite precision. After a considerable
amount of experience, lasers have been successfully
integrated into routine IVF practice, and are now found
in most advanced and well-equipped IVF labs the world
over. The advantages of a laser are multiple –
it is precise; atraumatic, and non-contact , which means
there is no need to touch the egg or embryo when using
the laser. At Malpani Infertility Clinic, we use the
Saturn IVF laser manufactured by Research-Instruments,
UK, one of the pioneers in this field.
The initial concerns regarding the safety of the laser
have now been put to rest after years of extensive experience
with lasers in IVF labs the world over. Lasers now allow
us to safely perform cellular microsurgery in the IVF
lab, and are routinely used for assisted hatching in
many labs. Assisted hatching involves using the laser
to create a precise opening in the shell ( zona) of
the embryo prior to transferring it. Such an opening
helps the embryo to hatch more easily, thus increasing
the chances of it implanting successfully in the uterus.
After so many years of using the laser, doctors are
now exploring new frontiers with it in the IVF lab –
what else can we do with this remarkable tool to help
infertile patients ?
We use the laser routinely in our lab for performing
embryo biopsies for preimplantation genetic diagnosis
( PGD). The laser allows to create a well-defined opening
through the zona, through which it is possible to safely
and atraumatically remove a single blastomere from the
embryo. You can see what a laser assisted embryo biopsy
at www.drmalpani.com/pgd/laserbiopsy.htm.
Researchers have also used the laser for ICSI ( intracytoplasmic
sperm injection). The trickiest part of ICSI is the
technical difficulty involved in capturing a single
motile sperm and crushing its tail in order to immobilize
it prior to injecting it into the egg. Using a laser
beam , this can be performed with much greater ease
and speed, thus dramatically reducing the time taken
to perform ICSI.
ICSI can be especially difficult to perform when there
are very few eggs, or the eggs are fragile, because
these are easily damaged when the injection pipette
is introduced through the zona into the cytoplasm of
the embryo. Laser assisted ICSI allows us to create
a very small opening in the zona, through which the
injection pipette carrying the sperm can be easily carried
into the egg. This technique has been shown to reduce
damage to fragile eggs during ICSI, and increase fertilization
rates as well.
The laser also allows us to perform cellular microsurgery
on the embryo. For example, a study has shown that it’s
possible to achieve a dramatic increase in pregnancies
from frozen embryos with laser-assisted removal of dead
cells. Researchers at the European Hospital in Rome
have shown that removing necrotic cells from frozen
thawed embryos greatly enhances a patient's chances
of becoming pregnant. Based on other researchers' work
with mouse embryos, the doctors hypothesized that removing
dead blastomeres from embryos damaged in the freezing
and thawing process would prevent their release of toxic
metabolites that are harmful to the survival and development
of healthy cells and the embryo as a whole and would
result in higher pregnancy rates for their patients.
A pilot study was organized in which 235 couples who
had frozen embryos from prior IVF cycles were randomly
assigned to two treatment groups. Both groups had transfers
utilizing their undamaged and partially damaged embryos
that survived thawing. Three surviving embryos were
selected for each couple from a maximum of ten thawed.
Laser-assisted hatching was used to drill a small hole
in the embryos' outer membranes. Undamaged embryos were
then cultured without further manipulation. In the control
group, partially damaged embryos were also cultured
without any more treatment. In the study group, embryos
that had undergone some freeze/thaw damage were treated
by removing any dead cells they contained. Embryos were
transferred to the patients after 18 to 20 hours of
culture, during which the researchers observed that
74.3% of the partially damaged embryos in the treated
group divided, while only 27.5% of the partially damaged
control embryos divided. Monitoring their patients'
progress, they found that 40% of the study group established
an ongoing pregnancy compared to 11.4% of patients in
the control group. It was clear that the removal of
necrotic blastomeres greatly improved patients' chances
of becoming pregnant from a frozen/thawed cycle. The
randomized study ended and the treatment was made standard
in the hospital's Centre for Reproductive Medicine.
The researchers followed up with an observational clinical
series confirming the improvement in pregnancy rates:
34.5% from frozen/thawed cycles in which dead cells
were removed from their embryos. Prior studies, not
using this technique, have shown that rates of pregnancy
and implantation with frozen-thawed embryos range from
10% to 30% and 5% to 15% respectively. "It's very
exciting to see this new technique significantly increase
patients' chances of becoming pregnant using their frozen-thawed
embryos. For many of them, it will reduce the number
of IVF attempts they have to go through and could also
reduce their risks of having higher order multiple pregnancies
by giving them the confidence to transfer fewer embryos,"
commented William Keye, Jr., MD, President of the American
Society for Reproductive Medicine. (Rienzi, et al, Laser-assisted
removal of necrotic blastomeres from cryopreserved embryos
that were partially damaged, Fertility and Sterility,
Vol.77, No.6, June 2002).
What of the future ? It may be possible to use the
laser to actually perform “surgery” on chromosomes
in the egg and embryo, thus allowing us to correct and
repair genetic defects (for example , it may be possible
to remove an extra 21 chromosome found in embryos with
trisomy 21). Science fiction ? perhaps, but fiction
has a way of soon becoming reality in the IVF lab !
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