by: Casey O’Gradey
A Snapshot of Work Across the Sciences and Humanities
Dr. Melinda Fagan of the Rice philosophy department views her work from a unique academic vantage point. While her position is in the humanities department, she has spent much of her academic career in the sciences, obtaining her PhD in biology before moving on to study philosophy and the history of science. While she once practiced science in a laboratory, she now approaches the field exclusively as an academic. She currently teaches a course entitled “Perspectives on Stem Cells” – a joint collaboration between the bioengineering and philosophy departments. This past semester, I had the opportunity to work as a research assistant for her project in the philosophy of stem cell biology. This relatively untouched field of inquiry piqued Dr. Fagan’s scientific and philosophical interests. Connecting central concepts of stem cell biology with key issues in philosophy of biology, she takes an interdisciplinary approach that explores the horizons of both fields – drawing upon recent experimental advances in stem cell research along with innovative philosophical approaches to scientific understanding. Through a synthesis of these two sources, Dr. Fagan’s work articulates an accurate and useful model of scientific results in stem cell biology that benefits both philosophers of science and practicing experimental biologists. The following is a short expose of what I gathered to be the aims and methods of her work.
Defining Stem Cells: An Epistemological Evaluation
While stem cells have played a prominent role in modern medical research, scientists are still struggling to precisely define their status and nature within biological theory. Because they are oft perceived as objects of great promise, it is crucial that their place in modern cell biology is understood before their medical possibility assessed. Unlocking the potential for curative medical remedies make the need for a precise understanding of stem cell extremely important and urgent.
Stem cells are typically defined by two capacities – (1) production of more cells of the same type, i.e. self-renewal and (2) production of more differentiated cell types, i.e. differentiation potential. They are further categorized by the developmental stage of their host organism – embryonic, fetal, or adult. In experimental research, the most important distinction is between embryonic and adult stem cells. Experimental practices on the two types of stem cells have different standards and methods. In her epistemic criticism of stem cell biology, Dr. Fagan focuses on the experimental results of adult stem cell research, specifically research with blood stem cells, also known as hematopoetic stem cells (HSCs). These are the only stem cells routinely used in clinical practice during bone marrow transplants and are comparatively well understood by the scientific community.
Dr. Fagan’s analysis of scientific results in this area of research takes an epistemological approach. That is, an approach that seeks to evaluate how knowledge in the field is garnered through experimental and/or social practices. Her effort in this regard locates the epistemic units of blood stem cell research and traces their history and development to the present day. Drawing on the history and sociology of science, Fagan locates a crucial turning point in the field occurring in a debate between two groups of scientists both claiming to have discovered the proper method to yield all and only blood stem cells. While debate still surrounds this issue, Dr. Fagan determines the most widely accepted and used model of blood stem cells is one of cell-lineage hierarchy.
Under this model, cells are mapped according to their development from unspecialized stem cells toward fully specialized cells within an organism. Thus, at the top of this hierarchy is the unspecialized stem cell and branching off from it the different specialized cells it can potentially differentiate into. This model, while practically useful and accurately representative of the field, brings out many philosophical problems in the field that Dr. Fagan uncovers and attempts to explain.
Questions in the Philosophy of Stem Cell Biology
The model is useful because it provides a meaningful definition of stem cells using the concepts of self-renewal and differentiation. The central question that Dr. Fagan address under this model is whether stem cells have intrinsic nature; that is, whether stem cells are real ontological entities. This is a problem found in philosophy of science and philosophy of biology. In this instance, the concern is that the model fails to take into account the environmental condition under which a cell can be described as a stem cell. The model tacitly assumes that cells are selfsufficient and isolatable entities when in fact that may not be the case. Philosopher of science Nik Brown writes, “Of late, the traditional notion of stem cells as a clearly defined class of intrinsically stable biological objects that can be isolated and purified, has begun to give way to a view of ‘stem-ness’ as temporary, shifting and evanescent.”
Ultimately, whether stem-ness is an intrinsic quality of acell depends upon the explanation of biological mechanisms invoking stem-ness. Because stem cell biology is a relatively new field of experimental biology, an assessment of mechanistic explanations in this field demands not only an evaluation of biological theory, but also a social analysis of stem cell experimental practices. Through a historical survey of the field’s work, Dr. Fagan determines unification as a guiding norm of experimental practice in the field.
Ultimately, Fagan concludes that a reasonable way to conceive of objectivity in stem cell biology is to distinguish between experimental and biological mechanisms. This would allow scientists to delineate between experimental interventions and the actual nature of the biological objects on which they intervene. Dr. Fagan concludes on the matter, “For a therapy to work, it is not enough that the models it is based on mesh with our aspirations and hopes. They must also successfully predict what cells will do when let loose in the body. So it is crucial that stem cell researchers be able to distinguish between features of models of cell development that reflect our interventions and aspirations, and those that reflect ‘cell intrinsic’ pathways or stable features of physiological environments.”
Dr. Fagan is keen to note in this passage that ethical and epistemic values often intersect with medical science, particularly those of public interest, like stem cell biology. The crucial aim of her project is to demonstrate the importance of this interplay for further understanding the science in which we are working and the goals we hope for it to accomplish. Stem cell biology is a unique and constitutive case of this dynamics because it is both a relatively new area of experimental biology as well as a prominent topic of medical promise.