New treatment boosts bone healing and regrowth

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New treatment boosts bone healing and regrowth

Findings could lead to new treatments for fractures, bone disease

and other musculoskeletal disorders

http://www.eurekalert.org/pub_releases/2008-01/uoaa-ntb010908.php

A drug originally used to treat iron poisoning can significantly

boost the body's own ability to heal and re-grow injured bones,

according to researchers at the University of Alabama at Birmingham

(UAB).

The researchers injected the drug deferoxamine (DF), which is

designed to reduce iron overload, into injured mouse bones. They

found DF triggered the growth of new blood vessels, which in turn

kicked off bone re-growth and healing.

In the study, bone density surrounding the injury more than doubled

to 2.6 cubic millimeters in treated bones compared to 1.2 cubic

millimeters in untreated bones, the researchers said. The new blood

vessel growth and bone healing was achieved through a cell pathway

that helps the body respond to low oxygen levels, a common problem

when blood supply is affected by bone fracture and disease.

Findings on this cell pathway have broad implications for improving

treatment of bone fractures, bone disease and other musculoskeletal

disorders, said Gilbert, M.D., an assistant professor of

orthopedic surgery in the UAB School of

Medicine, and Chao Wan, M.D. Ph.D., an instructor in the UAB

Department of Pathology, both co-authors on the study.

" With DF activating this pathway, we've proven a significant point –

it is possible to explore new, safe and more affordable ways kick-

start bone repair, " Gilbert said.

" Current treatments use complex proteins, which are expensive to

make and cost thousands of dollars per dose. The type of agent used

in this study is a simple, small molecule drug that costs hundreds,

not thousands, " Gilbert said.

The UAB findings are published in the online version of the journal

Proceedings of the National Academy of Sciences and will soon appear

in a print edition.

" The results from this study are a milestone for future studies

looking at other compounds and agents to improve new-blood-vessel

growth in skeletal and other tissues that need adequate blood supply

to regenerate, " Wan said.

The UAB tests were performed in conjunction with a bone lengthening

procedure commonly used in children and adults, and has proven to

aid bone healing. The study mice were anesthetized for surgery, and

one leg bone was cut clean through and a pulling device attached

temporarily to stretch the bone gap for the next 10 days.

During the stretching, the bone gap was injected with five DF doses.

Two weeks after the last DF dose, X-rays of the mice legs were taken

to measure bone regeneration.

DF is a drug that binds to excess iron in the body and helps with

excretion through the bowels and bladder, a process sometimes called

iron chelation. DF is used to treat a variety of medical conditions,

including iron overload, transfusion-related blood poisoning and in

combination with dialysis.

In the findings on post-treatment increased bone density, the UAB

researchers found significant increases in the number of new blood

vessels, and excellent connectivity between those vessels. The new

blood vessels are required regenerate bone of equal or better

strength than the original bones.

Gilbert said it follows that this cell pathway is a prime target for

future human studies using DF and other drugs to strengthen the

body's bone-healing potential, especially since poor blood supply is

common in fractures and bone disease.