Theodor Schwann Bicentenary

"The treatise has now been seven years before the public, has been most acutely investigated by those best competent to test its value, and the first physiologists of our day have judged the discoveries which it unfolds as worthy to be ranked amongst the most important steps by which the science of physiology has ever been advanced"

The treatise being described here is Theodor Schwann's work of 1837, Mikroskopische Untersuchungen über die Uebereinstimmung in der Struktur und dem Wachsthum der Thiere und Pflanzen. This was translated into English in 1847 as Microscopical researches into the accordance in the structure and growth of animals and plants (the quote above comes from the Translator's Preface). But to summarise Schwann's achievements, let's just use two words: cell theory.

Schwann - who was born 200 years ago today - played a key role in our understanding that cells are the basic units of life. Schwann's associate Matthias Schleiden had examined the cellular structure of plants, but Schwann extended Schleiden's research to animal tissues. As the title of Section II of Schwann's Microscopical researches... states: "On cells as the Basis of All Tissues of the Animal Body".

Schwann's work was aided by developments in nineteenth century microscopy. Microscopical researches... includes a number of plates with figures of the cells Schwann observed under his microscope (magnified by about 450 diameters). Here were membranes from a hen's egg and cells from the tail of a tadpole, not served up as remarkable feats of magnification but as evidence to support his theory.



Aided by being part of the laboratory of the influential German physiologist Johannes Muller, Schwann's monograph caught the attention of the scientific community and he was awarded the Royal Society's Copley Medal in 1845 (two years before his work was published in English).

Although Schwann's theory was refined in later years (Rudolf Virchow showed that cells developed from themselves, rather than as Schwann argued, crystallizing out from a "blastema" or amorphous fluid) he played a vital role in the adoption and acceptance of cell theory. Considering also Schwann's earlier research - he made pioneering discoveries in both fermentation and digestion - the bicentenary of his birth seems an apt date to mark.

Henrietta Lacks and HeLa

59 years ago today, Henrietta Lacks was diagnosed with cervical cancer. Few would have guessed the impact the cells taken from her tumour would have on cancer research, drug testing, and the discovery of vaccines.

Until 1951, no researcher had been able to grow human cells in culture for more than a few weeks. But Dr George Otto Gey of Johns Hopkins Hospital, Baltimore, USA, found that cells taken from Henrietta’s tumour grew outside of her body indefinitely, no doubt due to the aggressive nature of the tumour from which they came. He named these cells HeLa, after Henrietta, and sent them to his colleagues. HeLa was seen as a breakthrough, possibly even the cure for human cancer. Within two years of their initial discovery, 600,000 cultures were shipped for use in research.

One of the first applications of HeLa cells was in the discovery of the polio vaccine. The polio virus could grow in HeLa cells, which enabled the growth of the large amounts virus required to produce the polio vaccine, subsequently developed by Jonas Salk.

HeLa cells are an immortal cell line – they can be split and proliferated as many times as required without the quality of the cells deteriorating over time. They have an active version the enzyme telomerase during cell division, which prevents the shortening of telomeres that is thought to result in eventual cell death. This results in an endless supply of cells.

HeLa is still the most widely used human cancer cell line and it is estimated that the total number of HeLa cells that have been propagated in cell culture far exceeds the total number of cells that were in Henrietta Lacks's body. Henrietta died eight months after her cells were taken, never knowing the contribution she made to scientific research, or how she indirectly saved many lives.

(Wellcome Images holds a range of HeLa images. Shown above are HeLa cancer cells undergoing mitosis: click on the image for more information).

Author: Louise Crane