Quantitative measurement of cell membrane transport: technology and applications.

The transport of water and cryoprotective chemicals across cell membranes plays an absolutely fundamental role in the outcome of cryopreservation processing. The diversity of cell types as well as the remarkable range of perturbations that cells are subjected to as part of cryopreservation practices generate many interesting research questions. Simply stated, the extreme conditions typical of cryopreservation protocols extend the limits of membrane transport inquiry well beyond that considered in "normal" cell physiology. This paper provides a brief review of methods which have been used for measuring membrane transport properties, especially those methods developed during the past decade which allow us to measure coupled and uncoupled membrane transport properties of water and cryoprotective agents for individual cells in terms of classical Kedem-Katchalsky membrane transport theory. Representative results obtained from these new technologies will be offered to illustrate their utility and relevance to membrane transport issues arising in cryopreservation practice. Engineers have made significant contributions to this area of research primarily in terms of device development and the application of inverse methods to estimate membrane transport properties.