Introduction to Stable Cell Lines and the Importance of its Establishment

Posted by beauty33 on June 15th, 2021

Cell lines are often used in place of primary cells to study biological processes. However, care must be taken when interpreting the results as cell lines do not always accurately replicate the primary cells. Types of cell lines including finite cell lines and infinite cell lines. Cell line development is the process of establishing a clonally-derived cell population, which has been genetically engineered to express a desirable phenotype (such as producing large amounts of recombinant protein) for a stable period.

Cell lines and cell cultures have been identified as playing an important role in the study of physiological, pathophysiological, and differentiation processes of specific cells. It allows the examination of stepwise alterations in the structure, biology, and genetic makeup of the cell under controlled environments, which provides scientists with great insights into the biological processes of human cells.

The instability of the cell line is of great concern as it may adversely affect the integrity of the product. Since 2012, Chugai, a Japanese pharmaceutical company, has successfully established the world's first stable cell line with colon cancer stem cell properties, and its great potential has attracted the attention of an increasing number of scientists and researchers. Stable cell lines have become a powerful tool for countless applications including vaccine production, testing drug metabolism and cytotoxicity, production of recombinant antibodies and proteins, the study of gene function, generation of artificial tissues (e.g., artificial skin) and synthesis of biological compounds (e.g., therapeutic proteins).

Major challenges for generation of stable cell lines are low transfection efficiency and/or integration frequency. Stable transfection requires the integration of marker genes (transgenes) into the host genome and the maintenance of transgenic expression even after host cell replication. And stable expression can be influenced by the transfection method used. The transfection method determines the cell type for stable integration.

Broadly, two steps are required to produce stable cell lines. First, the exogenous plasmid DNA is transfected into the host cell line. The next step is to apply antibiotics to select only those cells that show the desired plasmid DNA expression. The nucleic acid to be inserted may be in the form of plasmid DNA and encode microRNAs (miRNAs), short interfering RNAs (siRNAs), or full-length mRNA transcripts.

Recently, scientists from Sun Yat-sen University, China, reported and validated a newly-designed dual fluorescent reporter virus DFV-B. Its infection in primary CD4+ T cells can directly label latently infected cells and generate a latency model that was highly physiological relevant. Applying DFV-B infection in Jurkat T cells, they established a stable cell line model of HIV-1 latency with diverse viral integration sites. High-throughput compound screening with this model identified ACY-1215 as an effective latency reversal agent. This opens up a new way to explore the key events of HIV-1 incubation period and provides a valuable tool for studying the functional therapy of AIDS.

Apart from various applications, stable cell lines have an advantage over transient transfection lines because they allow the mass production of similar cells. Although a generation of transiently-transfected cells cannot pass on modifications to offspring, stably-transfected cells will pass on all genetic modifications to the next generation.