A Protein Could Help Millions with Osteoporosis

By Sondra Forsyth

Administering a bone-building protein intravenously stimulates bone formation via the regenerative ability of stem cells, according to a new study by UCLA researchers.

The results of the investigation into the protein NELL-1 could one day have an impact on the development of a treatment for osteoporosis, which affects more than 200 million people worldwide, according to a news release from UCLA. It may also help those with traumatic bone injuries, such as members of the military or even astronauts who lose bone density while in space.

The study was published in the journal Nature Communications. It was led by co-senior authors Dr. Kang Ting, chair of orthodontics and the division of growth and development in the UCLA School of Dentistry and Dr. Chia Soo, professor and vice chair for research in the UCLA Division of Plastic and Reconstructive Surgery in the David Geffen School of Medicine.

“Our end goal is really to harness the bone forming properties of NELL-1 to better treat patients with diverse causes of bone loss, from trauma in military personnel to osteoporosis from age, disease or very weak gravity, which causes bone loss in astronauts,” said Ting, who discovered NELL-1 in 1996.

According to the news release, bone is constantly being broken down and resorbed into the body and then rebuilt in a process called bone remodeling. The two cell types in charge of this process are osteoblasts (which build bone) and osteoclasts (which resorb — or break down — bone). When osteoblasts and osteoclasts work in normal balance, bone remodeling is a beneficial process. But, as people age, bone resorption naturally outpaces bone formation, resulting in some loss of bone density.

“For the millions of people living with osteopenia and osteoporosis, and others with bone loss, the function of these cells is out of balance,” said Soo, who is also research director for UCLA Operation Mend, which provides medical care for wounded military personnel. “We wanted to see how balance could be restored through the use of NELL-1.”

In their study, the researchers exposed adult stem cells that have the ability to create the bone-building osteoblasts, known as mesenchymal stem cells, to NELL-1 in the laboratory. The team found that mesenchymal stem cells exposed to NELL-1 in the laboratory created osteoblasts that were much more effective at building bone.

Next, the researchers administered NELL-1 intravenously in animal models and for the first time showed that NELL-1 could have this same effect on mesenchymal stem cells within the body. Furthermore, the team found that NELL-1 reduces the ability of osteoclasts to resorb bone. The study showed that this dual effect on both cell types significantly increased bone density.

“Our findings are exciting because they have big implications for possible clinical application in the coming years,” said the study’s first author, Dr. Aaron James, chief resident in anatomic pathology in the David Geffen School of Medicine.