January 16, 2015

This is a schematic of the head of a femur (the thigh bone), showing OCR stem cells in red and the growth of bone (green), cartilage and stromal cells. (Credit: Mike Barnett/Columbia University Medical Center)

Brett Smith for redOrbit.com Your Universe Online

Researchers at Columbia University Medical Center (CUMC) have announced the discovery of a new stem cell in mice that is capable of regenerating both bone and cartilage, according to a new report in the journal Cell.

The study team found the new cells by following the activity of a protein called Gremlin1. When they transplanted the cells, called osteochondroreticular (OCR) stem cells, to a fracture site they saw that the cells aided in bone repair.

We are now trying to figure out whether we can persuade these cells to specifically regenerate after injury, said Dr. Siddhartha Mukherjee, assistant professor of medicine at CUMC and co-author of the new study. If you make a fracture in the mouse, these cells will come alive again, generate both bone and cartilage in the mouseand repair the fracture. The question is, could this happen in humans?

The researchers predicted that OCR stem cells will eventually be found in humans because we have a biological makeup similar to that of mice. The CUMC team said they were optimistic that their work could eventually lead to treatments for bone-degenerative diseases like osteoporosis and osteoarthritis in addition to therapy for bone fractures.

Our findings raise the possibility that drugs or other therapies can be developed to stimulate the production of OCR stem cells and improve the bodys ability to repair bone injurya process that declines significantly in old age, said Dr. Timothy C. Wang, another co-author and professor of Medicine at CUMC.

These cells are particularly active during development, but they also increase in number in adulthood after bone injury, added co-author Dr. Gerard Karsenty, a professor of genetics and development at CUMC.

The Columbia researchers were also able to show that the adult OCRs are unlike mesenchymal stem cells (MSCs), which lead to bone growth during adolescence and in adulthood. Scientists presumed that MSCs were the source of all skeletal system cells, but the latest research has revealed that these cells do not produce fresh bone and cartilage. The Columbia study implies that OCR stem cells serve this function and that both OCR stems cells and MSCs bring about bone repair in adults.

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Mice stem cells capable of regenerating bone, cartilage