Two proteins could be key to regenerating bone

Scientists at the University of Wisconsin-Madison are investigating two proteins that may aid in restoring bone. Image: Michael Dorausch/CC BY-SA 2.0

Several potential therapies for regenerating bone lost to disease or trauma are under investigation, from embryonic stem cells to novel chemical compounds. Now scientists at the University of Wisconsin-Madison are adding something new to the mix: two proteins in bone marrow that they believe regulate master cells in the bone-making process.

In a study published in the journal Stem Cell Reports, the scientists describe the proteins, called lipocalin-2 and prolactin. The proteins govern the activity of bone-marrow-based mesenchymal stem cells, which are responsible for making bone and cartilage, according to a press release.

A team led by Wan-Ju Li, UW-Madison professor of orthopedics and biomedical engineering, found that when they exposed mesenchymal stem cells to lipocalin-2 and prolactin, the process by which those cells lose their power to divide and grow slowed. That means it would likely be feasible to keep the stem cells active outside of the body—a critical first step towards being able to implant them into patients and prompt them to make bone, Li says in the release.

To test that hypothesis, Li’s team implanted the protein-treated stem cells into a mouse model of bone loss. The experiment was a success, according to the release.

Other efforts to restore lost bone continue to show progress. Belgium-based Bone Therapeutics, for example, is in Phase II trials of its allogeneic cell therapy to treat lumbar spinal fusion. It hopes to produce a series of positive data readouts this year. And scientists at Scripps Research Institute have investigated a novel compound that when applied directly to mesenchymal stem cells seems to promote the growth of bone precursor cells called osteoblasts.

The next step for the UW-Madison team is to prove they can use lipocalin-2 and prolactin to generate large stores of high-quality cells in the lab, and then figure out the most effective method for implanting them into human patients and coaxing them to develop into bone. “We’re seeking better treatments for bone repair,” Li says.