Storage of cryopreserved reproductive tissues: evidence that cross-contamination of infectious agents is a negligible risk

A reliable procedure for decontamination before thawing of human specimens cryostored in liquid nitrogen: three washes with sterile liquid nitrogen (SLN2)

“…We fully agree with the majority of embryologists and cryobiologists that, in human IVF cryobanks, crosscontamination of infectious agents is a negligible risk (6,(11)(12)(13). Furthermore, the increasing practice of cryostoring in hermetically sealed cryocontainers and the use of straw in straw combined with certified SLN 2 (6, 10, 19-21) allow an aseptic cryopreservation even for the riskiest procedures such as open vitrification.…”

“…For these reasons, LN 2 /NV cryostorage is potentially hazardous because it can cause the contamination of the culture environment during the thawing procedure (10). Even though, in over 25 years, there has been no direct evidence of disease transmission by transferred cryopreserved human and animal embryos (6,(11)(12)(13), at the same time we have no information regarding possible negative effects of LN 2 /NV infectious agent contamination on the outcome of IVF frozen cycles; some microorganisms able to survive in LN 2 /NV may negatively affect gametes and embryonic development at warming (4,(14)(15)(16). Furthermore, vitrification is increasingly used for human reproductive cells and tissue; this cryoprocedure appears to be riskier than slow freezing owing to the direct contact between cells/tissue and the LN 2 required for open systems.…”

Viral screening of spent culture media and liquid nitrogen samples of oocytes and embryos from hepatitis B, hepatitis C, and human immunodeficiency virus chronically infected women undergoing in vitro fertilization cycles

“…The poor performance of oocytes and embryos as vectors of pathogen agents is explicable by their nature; oocytes are isolated cells with no blood supply, and embryos contain a small number of cells, both of which marks a great difference with all other types of tissue. These aspects should be considered when establishing the guidelines and regulations for donation of cells and tissues (20).…”

Contaminação microbiológica em laboratório de reprodução humana e suas implicações no sucesso da reprodução assistida

“…Em estudo de revisão, conclui-se que há um risco negligenciado de contaminação cruzada em condiç ões de FIV. 15 Encontrou-se relação entre infertilidade e vírus da hepatite C em um grupo de casais inférteis, com prevalência de 3,2% para as mulheres e 3,6% para os homens, 16 que pode ser transmitida de uma mulher para outra pela contaminação transvaginal por equipamentos ou dos pais para o concepto. Recomendou-se que pacientes inférteis fossem rastreados antes de submetidos a técnicas de reprodução assistida.…”