Successful vitrification and safe storage
In summary, these studies confirm that Rapid-i allows successful vitrification and that results post-warming are similar to those obtained by well-established open carrier devices. The studies also demonstrate that the closed system of Rapid-i allows safe storage of human embryos at all developmental stages, avoiding any potential risks related to cross-contamination in liquid nitrogen, and contribute with good success rates.
Closed system minimises risk with cross-contamination
As Rapid-i is a closed vitrification system it overcomes the concerns associated with direct liquid nitrogen contact (the risk of cross-contamination between samples valid for all open carriers). Rapid-i has been compared to well-established open systems such as CryoLoop and Cryotop. Main outcome parameters in the different studies were post-warming survival and subsequent blastocyst development. Clinical data including implantation and clinical pregnancy was also presented.4,5,6,7,8
Safe, effective and easy to use
Altogether, results using Rapid-i are excellent with survival rates ≥95%, good blastocyst development, implantation rates ranging from 31-52%, and clinical pregnancy rates of 52-57%. The authors independently conclude that Rapid-i is a safe and effective carrier for vitrification by its prevention of contamination. Desai et al. have also shown that Rapid-i gives similar results for both cleavage-stage embryos and blastocysts 7,8, and claims its technical ease of use.
Rapid-i and sperm freezing
Evaluated recovery rates from cryopreservation of small number of spermatozoa with the use of the Rapid-i have been presented 9,10 . The results suggest that the method may be suitable for sperm vitrification, especially when there is only a low number of sperm cells available.
Table 1. Summary of results from the use of Rapid-i for vitrification of embryos/blastocysts presented in meeting abstracts 2011-2012.
*Abstract includes two experiments
Abstract 1. (REF 1)
Results after vitrification of donated day 5 blastocysts using a closed (Rapid-i) are compared to an open vitrification system (Cryoloop). There were no significant differences between the groups. An important difference between the two groups is that blastocysts vitrified on Rapid-i were cryopreserved twice. The authors suggest that the Rapid-i vitrification system can be introduced for clinical use.
Abstract 2 (REF 2)
The study compares results after vitrification of pronuclear (PN)-stage oocytes and cleavage-stage embryos using a closed system (Rapid-i) and an open system (Cryotop, Kitazato BioPharma CO). Donated, cryopreserved embryos were thawed, and allocated to vitrification using Rapid-i or Cryotop. After the second warming the survival and the percentage of embryos reaching the blastocyst stage on day 5 and day 6 were compared. There were no significant differences between the groups. The authors suggest that vitrification using Rapid-i is a safe and effective method for prevention of bacterial and/or viral contamination.
Abstract 3 (REF 3)
Survival and subsequent development of embryos vitrified on a closed carrier system (Rapid-i) are compared to an open carrier (Cryotop). Donated and cryopreserved two-pronuclear oocytes (2PN) and day-3 embryos were allocated to either of the two groups, and re-vitrified. There were no significant differences between the groups. The authors suggest that the Rapid-i vitrification system is appropriate for storage of human embryos. Rapid-i does not impair the potential of 2PN and day 3 embryos after warming as compared to the currently used carrier, Cryotop.
Abstract 4 (REF 4,5,6)
Vitrified and warmed pronuclear (PN)-stage embryos and blastocysts were included and results from vitrification using a closed carrier (Rapid-i) and an open carrier (Cryotop, Kitazato BioPharma CO) were compared. Donated and vitrified PN-stage embryos were included in Experiment 1 for assessment of survival rate and developmental competence, while high grade blastocysts (≥3BB) were used in Experiment 2 for assessment of clinical outcome. In both experiments embryos were warmed, allocated to either the Rapid-i or the Cryotop group and re-vitrified. Age of the patients did not differ between any of the groups. There were no significant differences between the groups. The authors conclude that introduction of a closed system would overcome potential problems associated with direct liquid nitrogen contact without impairing the developmental competence.
Abstract 5 (REF 7,8 )
Results from vitrification of both cleavage-stage embryos and blastocysts by the use of Rapid-i are retrospectively compared to results of the Cryoloop (Hampton Research, Laguna, CA). Expanded blastocysts were mechanically collapsed prior to vitrification. DMSO and ethylene glycol (EG) were used as cryoprotectants. Embryos were warmed in culture medium containing sucrose. Pregnancy outcomes were similar between the two carriers. The clinical pregnancy rate with blastocysts mechanically collapsed before vitrification on the Rapid-i was 63%. The authors conclude that the Rapid-i is effective for both early and late stage embryos, and state that embryo loading and recovery was technically easy to use.
- Seida K, Tanaka M, Suzuki H, Oshima S, Goto A, Satou Y, Sano K, Takeuchi I, and Yoshida A. Evaluation of the ultra-rapid method for vitrification using Rapid-i™. Presented at the Japan Society for Reproductive Medicine, Kanto region, 2011.
- Hoiruchi R, Mizuno S, Ogaki A, Miyaji S, Haruki A, Fukuda A, and Morimoto Y. Development of human embryos after freezing-thawing by Rapid-i™ method. Presented at the Japanese Society of Reproduction Engineering, 2012.
- Mizuno S, Ohgaki A, Miyaji S, Haruki A, Fukuda A, and Morimoto Y. Comparison of open and closed devices for vitrification of human embryos. Presented at the 4th Congress of the Asia pacific Initiative on Reproduction (ASPIRE), 2012.
- Ohsumi K, Hama S, Hashimoto S, Amo A, Satoh M, Akamatsu Y, Nakaoka Y, and Morimoto Y. Effectiveness of the closed vitrification device in frozen-thawed embryo transfer. Presented at the 4th Congress of the Asia pacific Initiative on Reproduction (ASPIRE), 2012a.
- Amo A, Hashimoto S, Hama S, Oosumi K, Nakaoka Y, and Morimoto Y. A closed vitrification system enables a safe and an aseptic vitrification without impairing the developmental competence of human embryos. Presented at the ASRM meeting, 2012. Fertility and Sterility, 98, 3, Supplement, S124, P-40.
- Ohsumi K, Hama S, Hashimoto S, Amo A, Satoh M, Akamatsu Y, Nakaoka Y, and Morimoto Y. The search for the next-generation of cryo preservation system: Examination of the closed vitrification device. Presented at the Japanese Society of mammalian Ova Research, 2012b.
- Desai N, Goldberg J, Austin C, and Falcone T. The new Rapid-i™ carrier is an effective closed system for human embryo vitrification of both the blastocyst and cleavage stage. Presented at the ESHRE meeting, 2012. Human Reproduction, 27, Supplement 2, ii59-60, O-154, 2012a.
- Desai N, Goldberg J, and Austin C. The new Rapid-i™ closed vitrification system is technically easy to use and gives excellent outcomes with both blastocyst and cleavage stage embryos. Presented at the ASRM meeting, 2012. Fertility and Sterility, 98, 3, Supplement, S129-130, P-60, 2012b.
- Egashira A, Otsubo H, Tanaka K, Matsukuma T, Murakmi M, Nagabuchi E, Tomohara A, Mine C, Ifuku M, Shiota M, Murakami K, Otsuka M, Yoshioka N, Araki Y, and Kuramoto T. Evaluation of cryopreservation of a small number of sperm in a non-liquid nitrogen contact system. Presented at the Japan Society of Fertilization and Implantation, 2011.
- Otsubo H, Egashira A, Tanaka K, Matsuguma T, Murakami M, Murakami K, Otsuka M, Yoshioka N, Araki Y, and Kuramoto T. Croypreservation of a small number of human spermatozoa in a closed system by using Rapid-i™. Presented at the ESHRE meeting, 2011. Human Reproduction, 27, Supplement 1, i181-182, P-150, 2011.