Virological issues in the use of cell therapies

The testing of cells and starting materials for biological medicinal products made from human sources has tended to focus on blood-borne viruses and those with a tropism for B lymphocytes, probably arising from the existing guidance on human monoclonal antibodies and experience with proteins fractionated from human blood. This may not be the best course although blood may contaminate starting materials. Other agents may be more likely contaminants, and it is essential to apply sound virological principles to ensure product safety, particularly in instances such as cell therapy where the product is a living cell which is intended to persist in the recipient for some time.