Assessment of the permeability properties of cryopreservation outer bags used in NHSBT
- PDF / 722,482 Bytes
- 7 Pages / 547.087 x 737.008 pts Page_size
- 92 Downloads / 136 Views
Assessment of the permeability properties of cryopreservation outer bags used in NHSBT P. Hogg . P. Rooney . R. Lomas . J. N. Kearney
Received: 6 September 2017 / Accepted: 2 January 2018 Springer Science+Business Media B.V., part of Springer Nature 2018
Abstract This study was carried out to investigate leakage/transport across the bag material of six outer cryopreservation bags in common use within NHS Blood and Transplant. In order to do this two different leak testing procedures; coloured dye and hydrogen tracer gas, were used. The data obtained show that a coloured dye cannot permeate through the materials both at room temperature and following storage at liquid nitrogen temperature (- 196 C). In addition, when filled with the smallest elemental molecule, hydrogen, in the form of a tracer gas, all of the bags only allowed trace amounts of hydrogen to escape, either through the seal or the bag material. The data indicated that each of the bag materials tested would be capable of preventing bacterial or viral crosscontamination as long as the material remained intact. Keywords Bags Liquid nitrogen Vapour phase Dye Hydrogen Contamination
Introduction NHS Blood Transplant (NHSBT) departments use a wide range of cryopreservation bags to store and P. Hogg (&) P. Rooney R. Lomas J. N. Kearney NHS Blood Transplant, Tissue and Eye Services, Tissues Development Laboratory, 14 Estuary Banks, Speke, Liverpool L24 8RB, UK e-mail: [email protected]
preserve cells and tissues. The majority of the bags are maintained in the vapour phase of liquid nitrogen (VPLN) but a few are submerged in liquid nitrogen (LN2). It has been reported that some viral particles and bacterial and fungal spores remain viable at LN2 and VPLN temperatures (Fountain et al. 1997). In the past there were reported instances of contamination in LN2 storage followed by bacterial and viral transmission when transplanted clinically—most notably hepatitis B (Tedder et al. 1995) reviewed by Rall (2003). There are two possible explanations for the cross contamination. Following rupture of bags containing bacterial/viral material, viable microorganisms will be present throughout the nitrogen container. These could lead to recipient contamination following administration, either as a result of microbes passing through the bag materials or seals, or simply as a result of gross contamination of the outer bag surface including the delivery ports leading to contamination during the administration procedure. In order to reduce these risks, the majority of biological materials are now stored in VPLN. Ultra low temperature plastics and bag designs have improved greatly in recent years but the anxiety still remains that contamination may occur even in VPLN due to convection currents and also the permeability of the bag materials themselves allowing viruses to pass through. Possible cross-contamination of stored materials in the vapour phase does not appear to be an issue in short term storage (Bielanski 2005; Abdel Hafez et al. 2011) and a re
Data Loading...
