All the HeLa cells used in biological research all over the world since the 50s stemmed from one sample of cells collected from one woman in 1951. That fact totally stumped me when I heard it a couple of months ago.
The book “The immortal life of Henrietta Lacks” by Rebecca Skloot is a fascinating and painful read. I had absolutely no idea that an African-American woman in her 30s from a very modest social background in Baltimore, dying of cervical cancer, was the source of the first human cell line. The name ‘HeLa’ stands for her name: Henrietta Laks, and the cell line has led to countless biomedical advances.
Nor did I know that cells could be ‘immortal’….
The story of the HeLa cells leaves you questioning the emergence of scientific ‘facts’ like that of an immortal cell line. What are the consequences of using tissue collected from one person as the basis for an overarching scientific model? Can these issues be hashed-out by using concepts from lifecourse epidemiology?
I am not a biologist, so some of the questions that I wondered about when reading the book are probably quite easily answered by biological scientists. But some of my questions are about science itself; its progress, its pretensions.
-I am a population scientist, so I ask how a baseline sample of n=1 is acceptable as the basis of so much subsequent biomedical research? Of course, I understand that the cells have since differentiated and been ‘purified’, but the original source: one individual woman’s cervical cancer cells, is surely relevant.
This brings me to my main line of questioning: Embodiment
A central tenet of lifecourse epidemiology is the notion of embodiment: how our environment literally “gets under our skin”. Nancy Krieger defined embodiment as: “a concept referring to how we literally incorporate, biologically, the material and social world in which we live” (Kreiger 2001). Embodiment occurs when experiences alter human development and biology, the way in which this happens is influenced by systematic differences in social environments that endure over time and can affect individuals over their lifecourse (Hertzman 2012). Embodiment occurs from conception via such interactions, leading to wellbeing or ill health throughout life.
The person behind the cell line, Henrietta Lacks, led a short, hard life. The book describes the structural violence experienced in her everyday life as a black girl growing up in a ‘racially’ segregated environment: little possibility of education, poor access to basic needs, physical violence, ethnic and gender oppression.
Through the process of accumulating harmful conditions from early life onwards, Henrietta Lacks embodied these hardships and ended up developing an aggressive form of cancer that cut her life short. Here, I have restricted thinking about embodiment to one generation, but of course Henrietta’s parents, grandparents and the generations of slaves she was descended from all contributed to her health trajectory. Her life and death exemplify the horrendous inequalities and social injustices of a fraction of US society throughout history.
Embodiment does not just refer to health states, but can be examined at much more detailed level. There is evidence for embodiment at the molecular level via epigenetic mechanisms. Epigenetics is the study of modifications occurring in the cellular micro-environment affecting gene expression. Social epigenetics refers to the process by which the environments in which we live influence chemical reactions converging on the cell structure (ex: chromatin) that in turn alter the ways our genes behave or are expressed.
What are the implications of taking such an extraordinary individual, and using her cells in biomedical research thereafter? Here are some of my questions.
-To what extent were Henrietta Lack’s cells, their structure, their genetic make-up, their gene expression, unique to her life experiences and family history?
-How might the uniqueness of such cells have an impact on biomedical hypothesis testing?
-How often have we made unconscious jumps between the individual and the population because of biological models?
-How far is the HeLa cell-line model now used different to the original cells collected?
Scientists can have a strong pretension that science is ‘objective’. But the HeLa cell-line story reminds us that science is created by individuals. Extraordinary individuals like Henrietta Lacks, as well as individual scientists and researchers. It makes me wonder what other human stories are behind some of our infallible scientific paradigms.
References & related
Skloot, R. The immortal life of Henrietta Lacks. 2011, Pan Books, London
Krieger N. A glossary for social epidemiology. J Epidemiol Community Health. 2001; 55: 693-700.
Hertzman C. Putting the concept of biological embedding in historical perspective. Proc Natl Acad Sci U S A. 2012; 109: 17160-7.