Stem cells are back in the spotlight after a Washington, D.C. district court issued a preliminary injunction halting the use of federal funding for research done using human embryonic stem cells.
|A colony of embryonic stem cells, from the H9 cell line (NIH code: WA09).
After simmering for nearly a decade on the backburner of public awareness, stem cells moved back to the forefront Aug. 23, when Judge Royce C. Lamberth of the District of Columbia District Court issued a preliminary injunction halting the use of federal funding for research done using human embryonic stem cells. In his ruling on the case of Sherley v. Sebelius, Lamberth found that using funds from the National Institutes of Health for human embryonic stem cell research violates a federal law, which states that federal funding of work resulting in the destruction of a human embryo is prohibited. Along with reigniting the ethical controversy over human embryonic stem cells, this court case promises to have far-reaching effects on the entire field of stem cell research.
A History of Stem Cells
Stem Cell Update
After a series of motions and hearings, on Sept. 28 the District of Columbia Court of Appeals permanently stayed the original preliminary injunction that barred use of federal funds for human embryonic stem cell research. This ruling means that National Institutes of Health review and funding of both new and renewing hESC grants can continue, as can intramural hESC research on the NIH campus.
Back at the district court level, both sides have submitted motions asking for summary judgment, which would allow Judge Lamberth to rule on the case in the absence of any further hearings. No date has been given for the ruling on summary judgment, though a decision is expected by the end of October. If these motions are denied, then a trial would be forthcoming.
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Stem cells have traveled a long path to the present. The idea that a cell capable of regenerating damaged tissue existed in the body originated during the 19th century. However, the first true stem cells, by definition able to both self-replicate and differentiate into other cell types, were not isolated until hematopoetic stem cells were derived from bone marrow during the 1950s. Later work identified so-called adult stem cells in various other tissue types, including neural and intestinal tissues. Though used successfully to treat ailments such as leukemia, adult stem cells generally are constrained to forming a limited subset of cell types, exist at an exceedingly low frequency and are difficult to isolate. Researchers realized that an ideal treatment would instead use a highly pure, highly plastic, easily obtainable cell source.
The search for cells that could meet these high standards began in earnest in the 1970s, when researchers turned their attention to mouse tumors known as teratocarcinomas, in which random collections of cell types, such as teeth and hair, grow. The presence of such a diverse group of cells in one location led to the idea that the tumors contained highly plastic progenitor cells that were capable of differentiating into all somatic cell types. However, initial attempts to isolate these progenitors, termed embryonic carcinoma cells, directly from teratocarcinomas were plagued by inefficient yields and variable developmental potentials.
After years of trying, the holy grail finally was obtained when embryonic stem cells were isolated directly from early stage mouse embryos in 1981. Compared with heterogeneous embryonic carcinoma cells, these cultures contained homogeneous populations of pluripotent cells able to form unique cell types from each of the primary germ layers (endoderm, mesoderm and ectoderm). Subsequent work led to the development of protocols for efficient transformation of embryonic stem cells into a plethora of somatic cell types, including pancreatic, neural and even hematopoetic cells.