Researchers generate bone

Researchers at the Harvard Medical School and the Harvard School of Dental Medicine have transformed vascular endothelial cells -- which line blood vessels -- into stem-like cells with the ability to generate bone, cartilage and fat cells.

Those cells might one day be used to create more efficient tissue engineering for therapies to treat osteoporosis, osteoarthritis, muscular dystrophy or Alzheimer's disease, said Damian Medici of Harvard Medical School, the lead author of the study, which was published Sunday in the journal Nature Medicine.

In an unusual twist, the researchers looked to the genetic mutation behind a rare, grisly and incurable disease called fibrodysplasia ossificans progressiva, or FOP, to bring about the transformation in the cells.

In patients with FOP, inflammation causes tissues to turn into cartilage and bone.  Over time, the patients' bodies more or less turn to stone.  Doctors don't know how to treat or cure FOP.  But this study suggests they might be able to mimic its effects to one day engineer tissues to treat other diseases.

The Harvard team learned that FOP transforms endothelial cells into bone because a mutated form of a gene called ALK2 in patients causes the body to produce proteins that make the cells ossify. By introducing the gene and by introducing the proteins into endothelial cells in the lab, the team was able to bring about the same process and create the stem-like cells.

"To my knowledge, our discovery is the first to show that the effects of a disease-causing genetic mutation can be replicated and used to treat other diseases," Medici wrote in an e-mail.

The original goal of the research was "to identify the mechanism of how bone forms in soft tissues of FOP patients," Medici wrote.  He said that the work might help doctors find a cure for the disease.

While triggering the process could help generate tissues to treat other ailments, shutting the process down could curtail FOP.  "By inhibiting the conversion of endothelial cells to stem-like cells, it should prevent the formation of ectopic bone in FOP patients," Medici said.

The group's future work will focus on treatments for FOP, he said.