User talk:Abdurahman Jewaro Kumbi Aruse/sandbox

Animal cell culture preservation
Liquid nitrogen is often used to preserve cells in tissue culture either in the liquid phase (-196 °C) or in the vapor phase (-156 °C). Freezing can be fatal to cells due to ice crystals, electrolyte changes, dehydration and pH changes. Several precautions are taken to minimize the effects of freezing. First@, a cryoprotectant that lowers the freezing temperature, such as glycerol or dimethyl sulfoxide (DMSO), is added (1). Furthermore, it is best to use whole cells growing in logarithmic phase and change the medium 24 hours before freezing. In addition, the cells are slowly cooled from room temperature to -80°C to allow water to move out of the cells before freezing. The optimal cooling rate is 1-3°C per minute. Some laboratories use isopropanol at room temperature and the vials containing the cells are placed in a container and the container in a -80°C freezer. The effect of isopropanol is that the tubes warm to freezer temperature slowly, about 1°C per minute. To maximize cell recovery during thawing, cells are warmed very quickly by placing the tube directly from the liquid nitrogen tank into a 37 °C water bath with moderate shaking. As soon as the last ice crystal has melted, the cells are immediately diluted into the preheated medium. Cultures should be examined daily by observing morphology, medium color and cell density. A tissue culture diary should be kept and should include: cell line name, media components and any changes to standard media, dates of cell division and/or feeding, calculation of cell doubling time, culture and any observations related to morphology (2). Abdurahman Jewaro Kumbi Aruse (talk) 12:43, 12 February 2024 (UTC)