What are the limitations of primary cells?

There are several limitations of primary cells. One limitation is that they require more time to grow than immortalized cell lines. Furthermore, they have restricted growth potential and eventually die due to this. After a certain quantity of cell divisions, it may become more difficult to culture and maintain a continuous cell line. Another drawback of primary cells is that cells which originate from different donors behave differently to the same stimuli, like pro-inflammatory cytokines. Another disadvantage of primary cells is that they are high in cost and also require a sufficient amount of handling experience. Their characteristics may change with each subsequent passage if ideal culture conditions are not maintained.