by Sophie Prosolek, Quadram Institute Bioscience, Norwich.
Cells; we’re made of trillions of them. In fact, the human body contains approximately 37.2 trillion cells, each fulfilling a specific and important function. Scientists’ ability to grow human cells outside the body has completely revolutionized our understanding of biology, helping researchers make new medicines and fight deadly diseases.
Understanding of cell biology has greatly advanced in recent years, thanks to improved cell culture techniques. By culturing cells (i.e. growing cells outside the body) scientists are able to perform experiments on living tissue, which they couldn’t possibly perform on a human being. This means they can get relevant, exciting new data without risking human life.
Growing enough cells to experiment on hasn’t always been easy. In theory, if cells are maintained in the right culture conditions, they will grow [relatively] happily outside the body. However, getting the growing conditions right is very difficult if you don’t actually know what cells do; this was a big challenge faced by historic scientists in the early days of cell biology.
Scientists have only been culturing cells since the 1950s, but cells have actually been known about for hundreds of years – we just couldn’t grow them. In 1665, the famous scientist Robert Hooke first remarked upon tiny ‘cellula’ he observed in a piece of work under a rudimentary microscope. Hooke’s ‘cellula’ were the rigid cell walls of the long-dead cork plant – no good for culturing. The first live cells were seen in 1674 by Antonie van Leeuwenhoek, the first person ever to observe microbes.
Figure 1: Leuwenhoek’s animalcules (This work is in the public domain)
Cells came to be understood as a unit of life, but still no one really understood what cells actually did. In the 1830s, two scientists (Theodor Schwann and Matthias Schleiden) came up with the first ‘cell theory’, in which they postulated that all cells must do three things:
- They must be a structural unit which builds a living being,
- They must be able to exist alone, as well as part of a larger organism, and
- They must form spontaneously – like crystals.
Of course, we now know that the third aspect of Schwann and Schleiden’s cell theory is wrong (new cells form by the division of existing cells in a process called ‘mitosis’), but nonetheless the mid-to-late 1800s saw interest peak in cell culture. Various scientists tried growing sections of living tissue outside the body, but their work was flawed and far from the cell culture of individual cells that scientists use today.
Finally, in 1951, in a miraculous, yet controversial, turn of events, Dr George Gey of John Hopkins University in Baltimore, succeeded in growing the first true culture of human cells. George Gey was the doctor of Mrs Henrietta Lacks*, a patient who arrived at John Hopkins Hospital with an extremely aggressive form of cervical cancer. Tragically Mrs Lacks didn’t outlive her cancer, but her cells did. Dr Gey removed a sliver of her cervix which he rushed straight to his lab for culture. Unlike any cells before, Henrietta’s aggressive cancer thrived in culture to become the infamous HeLa cell line from which all modern cell culture is based.
Figure 2: HeLa cells – Multiphoton fluorescence image of cultured HeLa cells with a fluorescent protein targeted to the Golgi apparatus (orange), microtubules (green) and counterstained for DNA (cyan) (Work is in the public domain).
Cultured cells have been crucial to countless scientific discoveries, including the development the first ever polio vaccine. Scientists were able to infect the new HeLa cell cultures with the inactivated polio virus and test the efficiency of the vaccine, ensuring that it was both effective and safe for human trials. This was a breakthrough for America, which had recently seen approximately 58,000 cases of polio in just one year. America was free of polio by 1994.
Cells; we now grow trillions of them. In fact, we grow all kinds of different cells outside the human body in complex culture systems. We explore their genetic make-up and exploit them for drug discovery, helping researchers create new medicines and fight disease. As a research scientist myself, I know the value of cells because I use them every day and simply could not do my work without them.
Since the first biomedical experiments on HeLa cell cultures, cell biology has advanced in leaps and bounds. Scientists are now able to grow lots of different cell types in complex 3D matrices, simulating real tissue and making experiments much more accurate. Thanks to cell culture, we are now entering a new age of biomedical research, where tissue engineering (growing new, human tissue from cultured cells) and stem cell therapy (re-programming new ‘specialised’ cells in culture) are not just a possibility, but a reality. Scientists have come a long way since Hooke saw his first ‘cellula’, but in this new golden age of cell culture, who knows what medical miracles we’ll achieve next.
*Henrietta’s battle against cancer became one of the most famous, controversial stories that modern biology has to tell. ‘The Immortal Life of Henrietta Lacks’ by Rebecca Skloot tells a detailed and compelling account of Henrietta’s battle with cancer, and the challenges her cells posed to her remaining family.
- Bianconi et al (2013) An estimation of the number of cells in the human body, Annals of Human Biology, 40(6): 463-71
- Hooke (1665) Micrographia: or, Some physiological descriptions of minute bodies made by magnifying glasses (first edition).
- Gest (2004) The discovery of microorganisms by Robert Hooke and Antoni Van Leeuwenhoek, fellows of the Royal Society, Notes and records of the Royal Society of London, 58(2):187-201
- Mazzarello (1999) A unifying concept: the history of cell theory, Nature Cell Biology, 1(1):E13-5
- Skloot, Rebecca (2010). The Immortal Life of Henrietta Lacks. New York: Crown/Random House. ISBN 978-1-4000-5217-2.
- Centers for Disease Control and Prevention (CDC) (1994). “International Notes Certification of Poliomyelitis Eradication – the Americas, 1994”. Morbidity and Mortality Weekly Report. Centers for Disease Control and Prevention. 43(39): 720–722.
My name is Sophie and I’m a 3rd year PhD student studying cell metabolism at the Quadram Institute in Norwich and a keen science communicator. As UEA SciComm Society President and a Pint of Science city coordinator, I have a particular interest in science journalism and media production. I’m also a keen amateur musician and in my spare time I enjoy writing music for myself and others. I tweet in a personal capacity as @InfraRedRum.