Removing Marrow Improves Bone Healing

New research from Yale University suggests removal of bone marrow could make the bones stronger and speed the healing of fractures. 

The scientists said the findings could help older patients avoid major surgery, such as for hip replacement. 

Marrow produces new blood cells and is rich in stem cells that help repair bones.  Many of the human body’s large bones have a cavity in which bone marrow collects.

Scientists treated rats using a technique to remove the marrow, and found the rats recovered more quickly as a result.

Agnes Vignery led the Yale team that performed the research, in which marrow was removed from the upper leg bone of anaesthetized rats. Some of the rats were treated with a hormone, called PTH, that encourages the growth of new bone, and both groups were X-rayed to examine bone recovery.

Initially, both sets of rats began to deposit new bone material at the center of the bone, in the space formerly occupied by the marrow. However, the rats that did not receive the extra hormone treatment saw this bone disappear within weeks, with marrow returning in its place. In those given PTH, the bone continued to grow without the marrow returning, with the overall strength of the PTH-treated bones even stronger than their owner’s completely unaffected leg.

The researchers said the technique could offer rapid growth of new bone in areas weakened by bone loss, adding that the loss of some bone marrow should not result in an inadequate supply of blood cells.

The procedure could offer humans the potential for a simple procedure using a needle to remove the bone marrow in a fractured bone rather than a more complex operation.

Dr Brendan Noble, from the University of Edinburgh, said that although the loss of bone stem cells seemed “counter-intuitive” initially, it was possible that other types of cells, such as those in membranes surrounding the bones, were involved in the recovery.

“Perhaps they are sufficient to take on the role,” he told BBC News.

Peter Kay, a consultant orthopedic surgeon at the Wrightington Hospital in Wigan, said removing marrow with a needle rather than performing a major operation to fix a fracture was promising idea.

“This sort of minimally invasive technique to replace surgery sounds controversial, but if you strengthen rat’s bones maybe there is potential,” he told BBC News.

The research was reported in the April 4, 2008 edition of New Scientist magazine. A preview of the article can be viewed here.

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