Human Reproduction, Vol. 16, No. 8, 1777-1778,
August 2001
© 2001 European Society of Human Reproduction and Embryology
Letters to the editor |
Vitrification of embryos and oocytes with 5.5 mol/l ethylene glycol and 1.0 mol/l sucrose
Assisted Reproduction Unit, Women's Hospital, Hamad Medical Corporation, P.O. Box 3050, Doha, Qatar
Dear Sir,
Chenet al. (2000a) have erroneously cited the group of Martino et al. (1996) as the original formulators of a vitrification solution consisting of 5.5 mol/l ethylene glycol and 1.0 mol/l sucrose (Martino et al.1996
; Chen et al.2000a). This vitrification solution was in fact designed by Ali and Shelton (Ali, 1992; Ali and Shelton, 1993a, b, c).
Vitrification can only be achieved by very high, often embryotoxic concentrations of cryoprotectant solutions. Consequently, it was imperative to formulate a non-toxic and efficient vitrification solution for cryopreservation by vitrification. Ali and Shelton (1993a) undertook a systematic and extensive investigation involving over 6088 permutations and combinations of cryoprotectant solutions in an effort to identify the ideal and least toxic vitrification solution. This study led to the identification of an ethylene glycol-based solution consisting of 5.5 mol/l ethylene glycol and 1.0 mol/l sucrose (called VS14) (Ali and Shelton, 1993a) which was the least toxic and most versatile of the 6000 solutions investigated. This vitrification solution was used to cryopreserve all pre-implantation stages of in-vivo generated mouse (Ali and Shelton, 1993b) and day 6 sheep embryos (Ali and Shelton, 1993c) with insignificant loss of viability in vitro or in vivo. Subsequent investigations suggested it to be useful for the cryopreservation of in-vitro generated day 2 embryos and established cell lines in the human (Ali et al. 1995; Ali, 1996a, b). Following these reports, a number of publications appeared on cryopreservation by vitrification of mammalian oocytes and embryos—including human—with the birth of live young, using a vitrification solution consisting of 5.5 mol/l ethylene glycol and 1.0 mol/l sucrose (Papis et al.1995; Martino et al.1996; Hong et al.1999; Chen et al.2000a, b; Choi et al.2000; Chung et al.2000; Yoon et al.2000). With a notable exception (Papis et al.1995), all other workers appear to be incorrect in their citations as to the originality of the said vitrification solution.
References
Ali, J. (1992) Factors affecting the ultrarapid vitrification and cryopreservation of embryos. PhD Thesis. Australian National University, Canberra.
Ali, J. (1996a) Developmental competence of unipronuclear and triploid day-2 human embryos after vitrification with VS14. Med. Sci. Res., 24, 377–378.
Ali, J. (1996b) Highly efficient ultrarapid cryopreservation of established cell lines by vitrification with VS14. Med. Sci. Res., 24, 837–838.
Ali, J. and Shelton, J.N. (1993a) Design of vitrification solutions for the cryopreservation of embryos. J. Reprod. Fertil., 99, 471–477.
Ali, J. and Shelton, J.N. (1993b)Vitrification of preimplantation stages of mouse embryos. J. Reprod. Fertil., 98, 459–465.
Ali, J. and Shelton, J.N. (1993c) Successful vitrification of day-6 sheep embryos. J. Reprod. Fertil., 99, 65
–70.
Ali, J., Bongso, A and Ratnam, S.S. (1995) Chromosomal analysis of day-2 human embryos vitrified with VS14. Med. Sci. Res., 23, 539–540.
Chen, S.U., Lien, Y.R., Chen, H.F. et al. (2000a) Open pulled straws for vitrification of mature mouse oocytes preserve patterns of meiotic spindles and chromosomes better than conventional straws. Hum. Reprod., 15, 2598–2603.
Chen, S.U., Lien, Y.R., Chao, K.H. et al. (2000b) Cryopreservation of mature human oocytes by vitrification with ethylene glycol in straws. Fertil. Steril., 74, 804–808. [Web of Science][Medline]
Choi, D.H., Chung, H.M., Lim, J.M. et al. (2000) Pregnancy and delivery of healthy infants developed from vitrified blastocysts in an IVF-ET program. Fertil. Steril., 74, 838–834. [Web of Science][Medline]
Chung, H.M., Seung, W.H., Hong, M.S. et al. (2000) In vitro blastocyst formation of human oocytes obtained from unstimulated and stimulated cycles after vitrification at various maturational stages. Fertil. Steril., 73, 545 –551. [Web of Science][Medline]
Hong, S.W., Hyung, M.S., Chung, H.M. et al. (1999) Improved human oocyte development after vitrification: a comparison of thawing methods. Fertil. Steril., 72, 142 –146.[Web of Science][Medline]
Martino, A., Songsasen, N. and Leibo, S.P. (1996) Development into blastocysts of bovine oocytes cryopreserved by ultra-rapid cooling. Biol. Reprod., 54, 1059 –1069.[Abstract]
Papis, K., Avery, H., Holm, P. et al. (1995) The effect of vitrification solution, equilibration time, and direct dilution method on survivability of equilibrated or vitrified bovine in vitro matured oocytes. Theriogenology, 43, 293 .
Yoon, T.K., Chung, H.M., Lim, J.M. et al. (2000) Pregnancy and delivery of healthy infants developed from vitrified oocytes in a stimulated in vitro fertilization-embryo transfer program. Fertil. Steril., 74, 180 –181.[Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||