cell culture is observed. Even more pronounced decreases in cell culture health is observed at faster freezing rates, to the point that the cell culture cannot maintain a cell density. The use of cryopreservation agents is also key to the freezing process. A common cryoprotection agent used is 10% solution of DMSO, which acts to protect the cells from the rupturing caused by ice crystals during freezing and during thawing. DMSO has been observed to be toxic to cells, and requires dilution after the cells are thawed. Thawing Rapid thaws are recommend in bringing the cells out of cryopreservation and starting up their normal metabolic processes. Minimizing the exposure of the cryovial and its contents to room, or ambient temperatures is important. Rapid thaws are important to prevent the contents of the vial from melting and refreezing rapidly, which could cause ice crystals to form rupture the cells in the vial. Thaws can be performed in a few minutes within a water bath at a temperature around 37 °C. Experimentation has shown that a slower thaw in a controlled environment such as an incubator also can be used to safely thaw cryofrozen cells. Thawing in an incubator avoids the risk of contamination involved in thawing in a water bath, however takes a significantly longer amount of time and resources. Post thaw, the cells need to be transferred from the cryovial into another vessel and resuspended in media. By diluting the concentration of the cryoprotection agent present, negative effects such as toxicity from the cryprotection agents on metabolically active cells can be mitigated. History Originally, scientists kept collections of cellular material for their own use, but not for the scientific community at large. The first person accredited with making a cell bank for widespread use was Kral, a Czechoslovakian scientist who created his cell bank collection in the late 1890s. Currently, there are a large number of "culture collections and bioresource centers" that serve an individual part of the process of bioengineering. Some examples of these include the World Federation for Culture Collections and the International Society for Biological and Environmental Repositories. In January 2003, the UK Stem Cell Bank was established to serve as a central unit for specimen collection and human testing. The National Stem Cell Bank was established in October 2005 in Madison, Wisconsin in order to serve as a repository specifically for stem cell lines. It currently