In vitro and in vivo viability of human blastocysts collapsed by laser pulse or osmotic shock prior to vitrification

Abstract

Purpose This study was designed to investigate whether artificial shrinkage, induced by a laser pulse or hyperosmotic sucrose solutions, improves in vitro survival and/or implantation of vitrified-warmed human expanded blastocysts. Methods Before Cryotop vitrification, the blastocoelic cavity was collapsed either by a laser pulse or sucrose solutions. Non-treated blastocysts were used as control. Post-warm blastocyst survival and implantation after transfer were examined. Implantation rate outcome was retrospectively analyzed by morphological grading and developmental kinetics of post-warm blastocysts. Results Survival rates in the three groups were high. Implantation rates in the laser-pulse group (59.7%) were comparable with those in the sucrose group (49.3%), and were significantly higher than those in the control group (34.2%). The proportion of blastocysts showing fast development tended to be higher when the blastocysts underwent artificial shrinkage treatment before vitrification. There was no clear correlation between morphology of post-warm blastocysts and implantation rate. Conclusion Artificial shrinkage treatment before vitrification is associated with an increased probability of fast-developing embryos, resulting in higher implantation rates.

Artificial shrinkage of blastocoel using a laser pulse prior to vitrification improves clinical outcome

“…Mukaida et al [27] reported significant improvement in survival rate and pregnancy rates in 40 blastocysts collapsed by laser pulse prior to vitrification compared to a retrospective control group; additionally, the delivery of healthy babies confirmed the safety of the procedures. Data collected by Iwayama et al [40] after vitrification found a significant increase in implantation rate from 34.2 to 59.7 % following AS treatment by laser pulse. Cao et al [39] found that survival rates and pregnancy rates of 208 blastocysts subjected to laser pulse AS pre-vitrification were improved, and that the laser pulse group was associated with a significantly higher hatching rate and lower premature birth rate compared with the 29-gauge needle AS group.…”

Successful pregnancy by vitrified–warmed embryo transfer for a woman with Kallmann syndrome

“…Very high survival has been observed for vitrifiedwarmed human blastocysts [20,21] and cleavage embryos [21], in vitro, by use of the Cryotop cryodevice. The vitrification procedure was developed by Rall and Fahy [22].…”

Laser Pulse Application in IVF

“…As the efficiency of embryo culture increases, supernumerary embryos are produced and cryopreserved for transfer in a future cycle (Iwayama et al, 2010;Gardner et al, 1998). One method of cryopreservation known as "vitrification" involves high molar concentrations of cryoprotectants and rapid cooling of the embryo at rates of -20,000 C°/min (Desai et al, 2011).…”

“…Artificial shrinkage of the blastocyst to reduce fluid volume in the blastocoelic cavity before freezing was investigated as a technique to increase survival and ultimately increase clinical pregnancy and implantation rates (Vanderwalzmen et al, 2002). This has been carried out by either mechanical puncture of the blastocyst cavity with a needle and withdrawal of fluid (Vanderwalzmen et al, 2002), use of osmotic shock to draw out fluid (Iwayama et al, 2010) or by using laser pulses to collapse the blastocyst (Mukaida et al, 2006) (Figure 4). In mechanical collapse, the inner cell mass of the blastocyst is positioned at 12 o'clock or 6 o'clock position.…”

“…A glass micro needle is introduced into the cavity of the blastocoel and then withdrawn, which results in collapse of the cavity over 30 seconds to 2 minutes (Vanderwalzmen et al, 2002;Mukaida et al, 2006). During osmotic shock, the blastocyst is passed through media with high concentrations of sucrose to essentially "dehydrate" the embryo (Iwayama et al, 2010). For laser collapse, a short duration laser pulse directed at the trophectoderm in a region away from the inner cell mass is delivered, shrinking the cavity immediately without additional manipulation of the embryo (Mukaida et al, 2006).…”