Primary cell cultures from human patients are an invaluable resource to study the molecular and cellular effects of particular mutations, but there are many limitations to this strategy, not least in the inaccessibility of certain tissues, for instance the brain. Even if the tissue is accessible, such cells are often challenging to culture, and cannot be maintained for extended periods of time, making genetic engineering difficult. Equally, many primary cultures consist of heterogeneous cell populations that are not necessarily consistent between samples, often complicating analysis. Although many immortalised cell lines also exist, these necessarily contain genetic aberrations that enable their continued culture, and therefore do not represent a highly physiological model of disease.
