Chapter 9: Human Tissue and Cell Culture
Working with Human Tissues and Cells
All unfixed human tissue and cells are to be assumed to be infectious (the concept of “Universal Precautions”) and must be handled using Biosafety Level 2 (BSL-2) practices and procedures. Persons who are exposed to these materials in the laboratory are considered to have potential exposure to bloodborne pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus (HBV), and must be included in the University of Nevada, Reno Bloodborne Pathogens Program. These persons must be offered the hepatitis B vaccination (they do not have to accept) and receive annual Bloodborne Pathogens Training (see Chapter 6). Cell lines, which have been characterized to be free of recognized Bloodborne pathogens, are exempt from the OSHA Bloodborne Pathogens regulations. The Institutional Biosafety Committee will make the final determination on exemption of cell lines based on evidence provided in the MOUA form submitted to the IBC.
Transmissible Spongiform Encephalopathies
Spongiform encephalopathies (Creutzfeldt-Jakob, Kuru, and related agents) are fatal prion diseases that have been demonstrated to be present in the brain and spinal cord of infected persons. Infectious prions have also been found in blood and other body fluids, and many other tissues in infected persons; however, neurological tissue contains the highest concentration and represents the highest risk of infection. Prions are resistant to conventional inactivation procedures including chemicals (e.g., formalin, alcohol), boiling, dry heat, and irradiation, and they can be present in fixed tissue from infected persons. Although neurological tissue (brain, spinal cord) represents the highest risk of infection, all tissues from humans and animals infected with these agents should be considered potentially infectious. Laboratory-associated infections have not been demonstrated; however, it is prudent to consider nerve tissue (even fixed tissue) potentially infectious. BSL-2 containment and practices are recommended for all activities utilizing known or potentially infectious tissues and fluids from infected humans and animals.
Human or animal pathogens might be associated with cell or tissue cultures. Cell cultures known (or suspected) to contain an etiologic agent or an oncogenic virus are classified at the same biosafety level as that recommended for the agent. The following cell cultures and tissues require BSL-2 or higher containment and procedures:
- All cultured cells derived from human sources, including immortalized and “well established” cell lines.
- All cultured cells derived from nonhuman primate tissue.
- All cultured cells exposed to, or transformed by, a primate oncogenic virus.
- All human clinical materials, such as samples of human tissue obtained from surgery, biopsy, or autopsy.
- All primate tissues.
- All virus-containing primate cultured cells.
- All mycoplasma containing cultured cells.
- Using cells of human origin invokes the Bloodborne Pathogens Standard and its specific training and work requirements (see the above information on working with human tissues and cells).
- Any exemption from the BSL-2 requirement must be approved by the IBC. Requests for exemption from the BSL-2 requirement must be submitted to the IBC with supporting information.