Open versus closed systems for vitrification of human oocytes and embryos

Vajta G, Rienzi L., Ubaldi F.M.

Reprod Biomed Online 2015 Apr; 30(4):325-33

Abstract: Vitrification is now the dominant approach for cryopreservation of human oocytes and embryos; however, serious dis- agreement persists, particularly about biosafety issues. Techniques are categorized as either ‘open’ or ‘closed’ according to occur- rence of direct contact between the medium and liquid nitrogen during cryopreservation. Advocates of closed systems emphasize the potential danger of disease transmission mediated through liquid nitrogen, and praise the safety of their approach; those who use the open systems refer to the lack of evidence of disease transmission and regard their systems as more consistent and effi- cient. The purpose of this review is to clarify whether open and closed systems are really open and closed; if closed systems are safe and free of any danger of contamination; if closed systems are equally efficient as open ones for cryopreservation of human embryos and oocytes by considering overall outcome; and finally, if ethical and legal concerns are sound when risks and benefits are considered in a broader sense. On the basis of these answers, implementation of rational measures to lower the theoretical danger of disease transmission are proposed while maintaining the achievements in cryopreservation that have contributed substantially to the advancement in assisted reproduction techniques during the past decade.
© 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

KEYWORDS: biosafety, closed, cryopreservation, disease transmission, open, vitrification