“We are like dwarfs standing upon the shoulders of giants, and so able to see more and see farther”
(often also attributed to Sir Isaac Newton)
Welcome, dear SIVBers, to the new year and the new decade! Frankly, I can’t say that I am too sad to see the “Naught” decade recede in the taillights; time to move on. I am ardently looking forward to a fresh decade, brimming with new potential. However, even though I am in anticipatory, forward-looking mode, I have decided to look retrospectively in this particular report.
The little homily I contributed to the last issue of In Vitro Report seemed to hit a chord with some of the membership. I received several emails regarding the topic, (which was, if you have forgotten: Nobel prizes, scientific achievement and the role of tissue culture) and I found this particularly heartening. First, I was delighted to know that someone actually reads the “President’s Report”. I rather suspected it was the sort of thing that everyone simply skipped over in the Report to get to the juicy news items inside. Secondly, I was astonished and delighted when one of those emails happened to be from Dr. Len Hayflick.
Dr. Hayflick, for those of you who don’t know, was an early member of the precursor to the current SIVB, the Tissue Culture Association. In fact, Dr. Hayflick joined the TCA shortly after it morphed from the Tissue Culture Commission (and more commonly referred to as the Tissue Culture Club). Dr. Hayflick is also a Lifetime Achievement Award recipient of the SIVB and is perhaps best known as the discoverer of the phenomenon now known as the “Hayflick Limit”. This eponymously named phenomenon refers to the fact that normal, non-cancerous cell populations have a finite capacity for cell division, approximately 50 doublings for normal human fetal fibroblasts. As Dr. Hayflick pointed out, cancer cells, in contrast, overcome this limit and hence become “immortal” in tissue culture and have the capacity for uncontrolled growth in vivo. Without Dr. Hayflick’s finding that normal cells are mortal, the concept that only cancer cells are immortal would not have been appreciated. Prior to this discovery, made by Dr. Hayflick and Dr. Paul Moorhead in 1961, it was thought that ALL cells were immortal. In fact, this discovery was so heretical at the time that it was rejected for publication by the Journal of Experimental Medicine. Luckily, the manuscript was accepted for publication by Experimental Cell Research1 and has since gone on to become one of the seminal works in cell biology, tissue culture, cancer and aging research. Having been cited over 3500 times, only one paper in 135,000 has been cited more.2 It also spawned a considerable amount of research that recently culminated in the Nobel Prizes being awarded to 3 researchers who elucidated the role of telomeres and telomerase in the Hayflick Limit and in the immortalization of normal cells into cancer cells. Truth be told, I think the Nobel Committee made a grievous error in not including Len Hayflick in the 2009 award for Medicine or Physiology, but this isn’t the first time I have felt the Nobel Committee missed a recipient, and I’m sure it won’t be the last. As Dr. Hayflick pointed out to me in his email, he graciously acknowledged that the Nobel Committee chose to recognize the “discoverers of mechanism and not the discoverer of the phenomenon”. While I am sure the snub of the Nobel Committee must have been very disappointing (and I can only dream of imagining what that would feel like), Dr. Hayflick has confided that he is “content with this” and “has no regrets”. Indeed, Dr. Hayflick has had a very rich scientific life, not limited to discovering “his” limit and working tirelessly to understand aging at a cellular level. He also established the first normal diploid human cell strains, including one, WI-38, that has been widely used in research and for human virus vaccine production, including the polio vaccine. He also discovered the cause of primary atypical pneumonia, a mycoplasma, first cultured on a medium developed by Dr. Hayflick. A rich career, indeed! The field of in vitro biology is indebted to brilliant scientists like Dr. Hayflick who have so effectively used cell cultures to address fundamental biological questions.
Receiving the email from Dr. Hayflick prompted me to look at the list of other Lifetime Achievement award winners for SIVB and it reads like a who’s who of plant and animal cell biology. Toshio Murashige, Sergey Federoff, Ian Freshney and others. I confess that some of the names were more familiar to me than others and I wondered, “How many of our younger society members know about the accomplishments of these researchers who pioneered the use of cell and tissue cultures?” So, I decided to explore the contributions of 2 early recipients of the Lifetime Achievement Award and attempt to put their work into perspective.
First, let me introduce Dr. Judah Folkman, Lifetime Award recipient in 1992. Dr. Folkman was the director of the Vascular Biology Program at the Children’s Hospital, Boston, Professor of Pediatric Surgery and Cell Biology, Harvard. He is best known, however, as being the “Father of Angiogenesis” and postulating the provocative (at the time) hypothesis that developing tumors require the formation of new blood vessels in order to grow.3 The extension of this hypothesis was that by blocking the development of new blood vessels you could “starve” tumors – the beginning of “anti-angiogenesis cancer therapy”. Naturally, when Dr. Folkman first postulated these ideas they were met with skepticism and open disdain. Not unlike Dr. Hayflick, Folkman’s first grant application to study the hypothesis was rejected outright by the National Cancer Institute. In the rejection notice, the committee noted, rather cheekily, “Therefore, tumor growth cannot be dependent upon blood vessel growth any more than infection is dependent upon pus.”4 Needless to say, Dr. Folkman and colleagues eventually proved them wrong by demonstrating that tumor growth was, in fact, angiogenesis-dependent and that tumors secrete diffusible factors that stimulate endothelial cell differentiation. In 1971, he and his team isolated the first angiogenesis tumor factor.5 The study of angiogenesis and anti-angiogenesis became one the most active areas of cancer research in the past few decades and nearly a dozen anti-cancer therapeutic drugs have been the result. Central to this research is Dr. Folkman’s and others’ use of endothelium and tumor cell cultures in the study of tumor growth, the isolation of angiogenic and anti-angiogenic compounds and the testing of therapeutic agents. In fact, one especially fortuitous discovery came from a contaminated endothelial culture that contained an interloping fungus that apparently wafted into the lab from outside, a not uncommon occurrence at the time due to construction and open lab windows. This particular fungus did not kill the endothelial cells but merely kept them at bay and Dr. Don Ingber, a post-doc in Dr. Folkman’s lab recognized the uniqueness of the response. He kept the plate instead of throwing it away (after asking Dr. Folkman’s permission) and eventually isolated a novel anti-angiogenesis compound from the fungus. Dr. Folkman and his colleagues ultimately extended the role of angiogenesis beyond cancer into other diseases and conditions, including rheumatoid arthritis and macular degeneration. Today angiogenesis is recognized as an essential component of tumor growth and “a host of other diseases”. There are a dozen drugs based on anti-angiogenic therapy, another 30+ are in clinical trials and nearly 1.5 million patients are treated with anti-angiogenic compounds annually. It is rumored that Dr. Folkman was on the short-list for the Nobel Prize for Medicine and Physiology for several years. Unfortunately, Dr. Folkman did not survive to receive that recognition, one of the few awards not in his collection. He passed away in 2008, in an airport lounge in Denver, on his way to give a talk at a conference.
The other recipient of the Lifetime Achievement Award in 1992 has had as profound an influence on plant tissue culture and plant biology as Dr. Folkman had on angiogenesis. Dr. Folke Skoog, of the University of Wisconsin, can very accurately be called one of the “Fathers of Modern Plant Tissue Culture”. Who among you plant biologists has not used Murashige and Skoog tissue culture medium?6 (Aside: Toshio Murashige is also the recipient of the very first SIVB Lifetime Achievement Award, 1991). Murashige and Skoog medium was the first fully chemically defined plant culture medium and has become the standard tissue culture medium for plant cell and tissue culture for nearly 50 years. The Plant Physiology paper that describes the media has been cited over 17,000 times and is, arguably, the most frequently cited article in the history of plant biology. That alone would have been enough to cement Folke Skoog’s reputation in the annals of plant physiology and tissue culture. But M & S medium is not Dr. Skoog’s crowning achievement. In 1955, Carlos Miller, a post-doc in Dr. Skoog’s lab, and fellow colleagues at the University of Wisconsin identified and characterized the first of a new class of plant hormones known as cytokinins.7 Purified from “aged” herring sperm DNA, the team determined the chemical structure of a specific cytokinin that they dubbed kinetin. They were able to chemically synthesize the compound and test it’s efficacy to promote cell division in a tobacco tissue culture bioassay. The cell division-promoting activity of kinetin permitted “the continuous growth of plant tissues in vitro” 8 and, in proper ratios with auxin, promoted shoot formation from callus tissue. The story of the discovery and elucidation of kinetin and cytokinin class of plant hormones is a fascinating one and is well chronicled in a 2005 Plant Physiology paper written by Richard Amasino.9 The discovery of kinetin may have been a crowning achievement of Dr. Skoog’s lab, but it certainly wasn’t the last, or the first discovery to be made. Over 20 years earlier, Dr. Skoog, working as a graduate student in Dr. Kent Thimann’s lab at Caltech, determined the role of auxin in controlling apical dominance in plants.10 His interest in plant growth hormones spanned nearly 4 decades and Dr. Skoog published a seminal work on the structure and function of cytokinins in 1967.11 I first became aware of Dr. Skoog as an undergraduate at the University of Wisconsin-Madison, while working in the Botany Department greenhouses in 1975. Of the 4 greenhouses I tended, one of them was solely devoted to growing tobacco plants. I found this somewhat mystifying as tobacco was not one of the crops I typically associated with Wisconsin. When I enquired about them I was told, “Oh, those are Dr. Skoog’s plants” Sufficient explanation for some, but still rather enigmatic to me, until the following semester when I took Plant Physiology and produced my first plant tissue cultures on Murashige and Skoog medium, using Dr. Skoog’s tobacco plants as the starting tissue. The rest, as we say, is history.
All three of the individuals I described above have had a profound influence that extends beyond their immediate labs, beyond SIVB and into society. These are individuals of greatness, clearly giants in their respective fields, whose contributions should not be forgotten or simply relegated to textbooks. And, while we may not always connect the name to the research, I argue their contributions do live on in the work that continues today as part of the scientific continuum. We see further now because of their past achievements and, to be sure, there is more greatness to come. Who among us today will be the Dr. Hayflicks, Folkmans or Skoogs of tomorrow? There are scientists among our membership today who will make contributions no less profound, no less influential and no less remarkable. There are giants walking among us. As Gerald Holton noted, “In the sciences, we are now uniquely privileged to sit side by side with the giants on whose shoulders we stand.”
Didactically yours,
Todd Jones, President
1Hayflick, L., and P. S. Moorhead. 1961. The serial cultivation of human diploid cell strains. Exp. Cell Res 25:585-621.
2Shay, J. W., and W. E. Wright. 2000. Hayflick, his limit and cellular aging. Nature Reviews Mol Cell Biol 1:72-76
3Folkman, J. 1971. Tumor angiogenesis. Therapeutic implications. N Engl J Med 285: 1182-1186
4Remembering Judah Folkman. Seeing Beyond the Headlights. http://www.childrenshospital.org/cfapps/research/data_admin/site2580
5Folkman, J., E. Merler, C. Abernathy, and G. Williams. 1971. Isolation of a tumor fraction responsible for angiogenesis. J Exp Med 133: 275-288.
6Murashige, T and F. Skoog. 1962. A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol Plant 15(3): 473-497.
7Miller, C.O., F. Skoog, F.S. Okumura, M.H. von Saltza and F.M. Strong. 1955. Structure and synthesis of kinetic. J Am Chem Soc 78: 2662-2663.
8Miller, C.O. 1956. Similarity of some Kinetin and red light effects. Plant Physiol 31: 318-319.
9Amasino, R. 2005. 1955: Kinetin arrives. The 50th anniversary of a new plant hormone. Plant Physiology 138: 1177-1184
10Thimann, K.V., and F. Skoog. 1933. Studies on the growth hormone of plants: III. The inihibiting action of the growth hormone on bed development. Proc. Natl Acad Sci USA 19: 714-716.
