Incubator (culture) - Incubator

Incubator

If a hot room is not available, it may be necessary to buy an equivalent dry incubator. Even with a hot room, it is sometimes convenient to have another incubator close to the hood for trypsinization. The incubator should be large enough, ∼50–200 L (1.5–6 ft3) per person, and should have forced-air circulation, temperature control to within ±0.2 °C, and a safety thermostat that cuts off if the incubator overheats or, better, that regulates the incubator if the first thermostat fails. The incubator should be resistant to corrosion (e.g., stainless steel, although anodized aluminum is acceptable for a dry incubator) and easily cleaned. A double chamber, or two incubators stacked, one above the other, independently regulated, is preferable to one large incubator because it can accommodate more cultures with better temperature control, and if one half fails or needs to be cleaned, the other can still be used. Many incubators have a heated water jacket to distribute heat evenly around the cabinet, thus avoiding the formation of cold spots. These incubators also hold their temperature longer in the event of a heater failure or cut in power. However, new high-efficiency insulation and diffuse surface heater elements have all but eliminated the need for a water jacket and make moving the incubator much simpler. (A water jacket generally needs to be emptied if the incubator is to be moved.) Incubator shelving is usually perforated to facilitate the circulation of air. However, the perforations can lead to irregularities in cell distribution in monolayer cultures, with variations in cell density following the pattern of spacing on the shelves. The variations may be due to convection currents generated over points of contact relative to holes in the shelf, or they may be related to areas that cool down more quickly when the door is opened. Although no problem may arise in routine maintenance, flasks and dishes should be placed on an insulated tile or metal tray in experiments in which uniform density is important.

Trypsinization Trypsinization is the process of using trypsin, a proteolytic enzyme which breaks down proteins, to dissociate adherent cells from the vessel in which they are being cultured. When added to a cell culture, trypsin breaks down the proteins which enable the cells to adhere to the vessel. Trypsinization is often used to passage cells to a new vessel. For experimental purposes, cells are often cultivated in containers that take the form of plastic flasks or plates. In such flasks, cells are provided with growth medium comprising the essential nutrients required for proliferation, and the cells adhere to the container and each other as they grow. This process of cell culture or tissue culture requires a method to dissociate the cells from the container and each other. Trypsin, an enzyme commonly found in the digestive tract, can be used to "digest" the proteins that facilitate adhesion to the container and between cells. Trypsinization is often done to permit passage of the cells to a new container, observation for experimentation, or reduction of the degree of confluency in the flask by removal of a percentage of the cells.