Until now, many scientists have been “by and large, considering all the bones as the same organ,” says cancer biologist Xiang Zhang at Baylor College of Medicine in Houston. Greenblatt and his colleagues “clearly and beautifully show” that vSSCs and long bone stem cells are “very, very different,” says bone biologist Noriaki Ono at the University of Texas Health Science Center at Houston, who supplied mice for the study but was otherwise not involved in it. This and other evidence led them to conclude that they had uncovered vertebral skeletal stem cells, or vSSCs. The scientists inserted the vertebral cells into the muscles of mice and observed that the cells produced progeny reminiscent of the range of cells found in the spine. They found that the stem cells from the two locations expressed markedly different sets of genes.
Working in mice, scientists in Greenblatt’s laboratory isolated stem cells from both the vertebrae and what are known as the long bones, such as the femur in the leg. These features led Greenblatt and his colleagues to suspect that they form through a different mechanism than other bones.
Spines are unique to vertebrate animals, and the spinal vertebrae don’t carry some of the proteins often thought of as characteristic of bones. The work appears on 13 September in Nature. Greenblatt and his team’s results, “I would argue, overturn this very old paradigm,” he says. This idea “is still the classic dogma that’s taught in medical schools,” says Matthew Greenblatt, a pathologist at Weill Cornell Medicine in New York City and a co-author of the latest study. One theory from the1940s proposed that forceful events such as coughs can momentarily reverse blood flow and jolt cancer cells into the vicinity of the spine, where they form new tumours. Scientists have discovered a new type of stem cell that gives rise to the backbone - and that helps to drive the frequent metastasis of breast tumours and other cancers to the spine.Ĭertain cancers, including those in the breast, prostate and lung, spread preferentially to the spine, but the reasons have been unknown.
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