When you are starting your cell culture research, the primary requirement is having cells, and to decide whether human primary cells or cell lines will be beneficial, is a major task! If you want a cell culture model that is closer to human in vivo environment, human primary cells are a better choice. Human primary cells offer much efficient research efficacy and publication validation if you are planning to have your research work published to inform the global scientific community. On the other hand, cell lines offer a much easier model to work with and are well established in literature but lack the part of ‘mimicking human physiology’.
Human Primary Cells
Human primary cells are directly isolated from tissues and therefore retain the morphological and functional characteristics of their origin. As we can see from Pastor et al., 2010, original tumor tissue from patients preserves several tumor markers and miRNAs. Cell lines do not retain original physiology or markers.
However, human primary cells do not live forever in passages and undergo senescence. With more passage numbers, primary cells also start showing morphological and functional changes. Therefore, it is always advised to use primary cells of lower passage numbers. Furthermore, primary cells also give an advantage of not using animal models, thus having an ethical upper hand.
Human primary cells come from human donors, donated organs, surgical specimens, post-mortem donors, etc. The source limitation is always there while working with primary cell cultures and therefore major planning is crucial while handling primary cells in case of experiments. Also, primary cell cultures derived from explants often do not make homogeneous cultures and purification of specific cell types are required. Primary cells also require additional nutrition and growth factors as they are more sensitive than cell lines. Read here for primary cell culture applications.
Human Cell Lines
Since the early 20th century, researchers have relied on cell lines to gain insights into cell biology and metabolism. Cell lines or immortal cell lines have become a widely used model in cell culture literature, becoming a known and optimized entity for drug studies, biochemical assays, bioactive production, etc. Researchers are comfortable with cell lines as they are cost-effective, work-friendly, and can run for more passages than primary cells. Cell lines are easy to manipulate and expand, making it preferable for multiple screening owing to an unlimited material supply advantage.
Although cell lines are easy to work with, the physiological relevance of those studies might not be high. They do not show resemblance to human body metabolism and physiology, or even morphology. The immortalization and serial passaging cause several variations in genotype and phenotype of these cells. Due to the lack of morphological or functional features, cell lines might not be able to induce relevant biomarkers. Therefore, it is always better to validate cell lines before use to make sure they are not misidentified or contaminated.
For more info on advantages and disadvantages of primary cells in culture, read here.