The attenuated viruses in the vaccine present the SARS-CoV-2 proteins on its surface, to which the body triggers a small immune response against these foreign invaders. Once propagated, these viruses are then purified to be used as the vaccine. This cell line is unique because they express genes necessary for the viral vectors to propagate. The HEK-293 cells will essentially act as a micro-factory for the mass production of these modified viruses. Here, attenuated viruses, such as adenovirus, are engineered to contain the genetic material for producing a SARS-CoV-2 protein: the spike protein the virus uses to hijack our own cells. To paint a picture for how this works, let’s look at AstraZeneca’s viral vector vaccine. The use of foetal cell lines by these teams has been considered crucial to their work this being because the cell lines can actually be used to produce the vaccine through the use of their intracellular machinery. Some of the most notable frontrunners, namely Oxford/AstraZeneca, CanSino and Moderna, are using the cell line HEK-293 as part of their development of a vaccine. A cure for Covid-19?Īs we speak, there is a global race to find a Covid-19 vaccine and, with the number of deaths continuing to rise worldwide, the pressure is on. It has been estimated that the vaccines developed using WI-38 and its derivatives have prevented 4.5 billion cases of disease globally. WI-38 was instrumental for the discovery of innumerable vaccines, such as for polio, rubella, measles and rabies. Along with the ease at which they can adapt to different environments and continue to grow rapidly, foetal cell lines have become a staple of the laboratory. Due to this trait, they can mimic the behaviour of different human cell types. Stem cells are cells that have yet to specialise. You might have heard of these cell lines before, but under a different name: stem cells. The physiological, structural and biochemical processes under controlled conditions could now be studied through these cells in vitro. What WI-38 cell lines made possible was our ability to instead model the activities of healthy human cells. For instance, whereas the cells in our body typically carry 46 chromosomes of DNA, HeLa cells are hyper-triploid and contain between 76-80 chromosomes. However, they came with their own limitations. Previously, tumour cells lines, such as HeLa cells, were used for experimentation of vaccines. Hayflick’s cell line WI-38 rapidly replaced testing on animal cells and tumour cells and emerged as the new protagonist in viral vaccine research. This meant that a single source of foetal cells could be cultivated to produce an infinite number of cells. Through experimentation, he found that these cells could be frozen, reconstituted and grown indefinitely. He obtained the initial tissue sample from a legal abortion of a 16-week-old foetus from Sweden. It all began in the 1960s with Leonard Hayflick’s discovery of the foetal cell line. Even though these abortions occurred with no relation to research, there is an ongoing dispute on whether we should be using them, and what moral implications this might pose on its users. The ethical opposition to their use arises from where these cells are derived, this being from the stem cells of aborted foetuses. These cell lines are incredibly useful because they are cells that have been immortalised and continuously cultured for decades. Foetal cell lines have been an essential tool for many scientific fields, especially for disease and vaccine-related research.
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