The science of stem cells: some implications for law and policy.
Bibliographic record
Abstract
Introduction There are few areas of modem biomedical research that have aroused as much controversy as stem Scientists, physicians, patients and patient advocacy groups tend to emphasize the potential therapeutic benefits. Others argue that the potential benefits of stem cells have been exaggerated. Entrepreneurs, and research scientists -- who are sometimes one and the same -- envision vast medical and financial profits from stem cell therapy. Religious leaders pronounce judgments based strictly on faith and their understanding of when life begins. Those in positions of political power are eager to remain in power and seek a position wherein the fewest number of people are offended by a given policy choice. At first sight, the development of stem cells does not seem to be very different from other scientific developments, except that in the case of stem cells, an understanding of the scientific facts of stem cell technology per se, the embryology and the associated terminology is critically important to making ethically sound policy judgments. The facts, definitions and terminology are confusing and are liable to misuse by those who seek to further a particular position. It is our position that a coherent discourse needs to be initiated so that regulation in this area, if undertaken, is rational, consistent and informed by a clear understanding of the science and the terminology. In this paper we provide a concise overview of the important scientific facts related to embryology and embryonic stem cells and highlight some recent scientific developments that are salient for the purpose of regulatory development in this field. Why such Enthusiasm over Stem Cells? Stem cells are exciting to physicians, scientists and patients because of their potential to develop into many different cell types, tissues and perhaps even organs that can possibly be used to treat large numbers of patients with a variety of diseases. (1) To scientists, stem cells offer a new way of exploring fundamental questions of biology, especially those pertaining to embryonic development. (2) In the living body, stem cells are believed to exist in small numbers in most organs including the liver, blood and brain. Stem cells have two crucial capabilities: (1) they divide repeatedly into stem cells of their own type; and (2) with appropriate stimuli they can develop or differentiate either into one particular tissue, into a small number of tissues or, as m the case of pluripotent embryonic stem cells, into potentially all types of tissue. (3) Embryonic Stem Cells For years, pluripotent embryonic stem cells have been viewed as the holy grail for many scientists, particularly developmental biologists. Murine embryonic stem cells were discovered about 20 years ago, but despite intense research, human embryonic stem cells have eluded scientists until recently. In 1998, almost simultaneously, two research groups in the United States (4) discovered how to purify embryonic stem cells and maintain them in culture in the laboratory. Thomson and his colleagues purified cells from spare embryos from IVF clinics. (5) Gearheart and his colleagues purified cells, functionally the same as Thomson's cells, from the gonadal ridges of early abortuses. (6) The type of cells described by Gearheart and his colleagues have been confusingly called germ cells. Embryonic stem cells (ESCs), as they feature in much of the current debate, are those cells derived from embryos at the blastocyst stage, which is approximately five to seven days after fertilization. (7) At this stage, within the blastocyst, there is a small fluid collection (cyst) in the embryo and at one pole of the cyst a specialized clump of cells known as the inner cell mass. It is from this inner cell mass that ESCs can be obtained. (8) Several research teams have now been able to establish cell lines in the laboratory that continue to divide into succeeding generations of daughter cells that are identical to the original ESCs. …
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.016 | 0.020 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.006 | 0.036 |
| Scholarly communication | 0.014 | 0.018 |
| Open science | 0.003 | 0.005 |
| Research integrity | 0.034 | 0.017 |
| Insufficient payload (model declined to judge) | 0.010 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".