The new Rapid-i carrier is an effective system for human embryo vitrification at both the blastocyst and cleavage stage

Abstract

BackgroundThe Rapid-i is a new FDA cleared closed carrier for embryo vitrification. The cooling rate of - 1220°C/min is far lower than that reported with open vitrification systems such as the cryoloop (−15,000°C/min). Little published data is currently available on this device. This study presents our initial clinical data, as well as live birth outcomes, with the Rapid-i. The efficacy of this device for the cryopreservation of cleavage, as well as blastocyst stage human embryos is also analyzed. We further compare outcomes to those achieved with the cryoloop, an “open” vitrification system routinely used in our laboratory.MethodsHuman embryos were vitrified at either the 8–10 cell stage or else the blastocyst stage. The vitrification protocol was: 7.5% DMSO/7.5% ethylene glycol (EG) (2–3 min) followed by incubation in 15% DMSO /15% EG (45 sec) before loading on the vitrification carrier. Cryoprotectant was removed during warming by sequential washes in 0.25 M and 0.125 M sucrose in culture medium. Clinical outcome data for frozen cycles between January 2011 and August 2012 were stratified according to carrier and cell stage. The student t-test and chi square test were used to compare results. P value of < 0.05 was considered significant.ResultsA total of 486 vitrified-warmed embryos were assessed and 92% of them were transferred. The clinical pregnancy rate (CPR) and implantation rate (IR) with Rapid-i vitrified blastocysts were 59% and 49%, versus 47% and 37%, respectively for cleavage stage embryos. This was not statistically different from results with the cryoloop vitrified blastocysts (CPR 46%, IR 38%) nor the cleavage stage vitrified embryos (CPR 49%, IR 35%). To date, there have been 31 deliveries of 34 healthy infants from Rapid-i vitrified embryos, with another 12 pregnancies still on-going.ConclusionsThe Rapid-i offers an excellent alternative to existing open vitrification devices for embryo cryopreservation at the 8–10 cell stage as well as the blastocyst stage. Use of this type of “closed” sealed system that prevents direct contact between the embryos and liquid nitrogen reduces the potential risk of sample cross-contamination or infection. These preliminary data and live birth outcomes have paved the way toward transitioning to a closed vitrification system in our own IVF program.

Survival, re-expansion and cell survival of human blastocysts following vitrification and warming using two vitrification systems

“…These findings confirm earlier results, which showed that warmed blastocysts that survived vitrification were not different from fresh blastocysts, in terms of quality, DNA and chromosome integrity, ultrastructure, and developmental competence [11,17,[22][23][24][25].…”

“…Others formulations are DMSO-free: some still employ small devices and require very small vitrification volumes (eg. Rapid-I™ kit, Vitro Life, Sweden, [11]), while others are volume independent, use larger straws which are easier to handle and allow for longer embryo exposure to vitrification solutions (e.g. Global Fast Freeze kit, LifeGlobal, LLC, Canada, [12,13]).…”

A closed system supports the developmental competence of human embryos after vitrification

“…For warming, only embryos and cooling device, which were not exposed to liquid nitrogen, were warmed in thawing solution, thus avoiding the risk of contamination. Recently, it has been reported that the implantation potential of human blastocyts vitrified with Rpid-i was comparable to that of counterparts with an open device [6]. However, the data was mixed with single and multiple blastocyst transfer, and the number of patients (22) was small.…”

Neonatal outcomes after the implantation of human embryos vitrified using a closed-system device

“…Therefore, these embryos are vitrified, cryopreserved, and warmed without direct exposure to liquid nitrogen. Another research group also revealed no significant difference between the use of closed and open vitrification systems in the survival rate or implantation rate [25]. Recently, a total of 114 infants were obtained from blastocysts vitrified using the same closed vitrification device [25] and another closed device [26].…”

“…Such cross-contamination could arise from direct contact of the solution containing the oocytes and embryos with the liquid nitrogen. Therefore, to avoid the possible risk of contamination, closed vitrification systems have been developed [15][16][17][18][19][20][21][22][23][24][25]. However, new concerns such as a potential rise in temperature caused by a heat sealer and a decrease in the cooling rate have emerged with these methods.…”