The laminar flow hood chosen for tissue culture work will vary with the types of tissues being handled, but a clean, sterile working area free of particulate contamination is essential.
Horizontal laminar flow hoods are useful for preparing standard cell cultures such as non-genetically modified plant tissues. However, if there is a chance of hazardous contaminants being produced, class 2 biosafety cabinets must be employed. One example would be a cell culture used to isolate and characterise the poliomyelitis virus.
Laminar flow in the viral diagnostic lab
Today, practically all the handling of polio cell cultures is carried out using class 2 biosafety cabinets. There are two reasons for this:
1. The cabinets maintain a clean, sterile working environment
2. They protect the environment and operator against air-borne contaminants
Class 1 cabinets would not be suitable, because the cultures would not be protected. Purity is essential to successful cell culture, as bacterial and fungal contamination can kill the cells and contaminate other cultures. Mycoplasmal contamination carries a particularly high risk, as mycoplasma bacteria are small enough to pass through a HEPA filter and are resistant to many of the antibiotics used to combat contamination in the lab. Viral particles are another concern, not only because they can influence virology results but because non-cytopathic contamination (in which the cells don’t die) can be hazardous to laboratory workers.
This last point shows why a normal laminar flow hood should not be used for this type of work. While the experimental area is protected, the user is at risk of contaminants from the cabinet.
List one: laminar flow hood
List two: Horizontal laminar flow /biosafety cabinets