How Youth Factor Can Help Repair Old Bones

As we get older things that used to heal quickly tend to take a little longer to get better. In some cases, a lot longer. Take bones for example. A fracture in someone who is in their 70’s often doesn’t heal as quickly, or completely, as in someone much younger. For years researchers have been working on ways to change that. Now we may be one step closer to doing just that.

We know that using blood stem cells can help speed up healing for bone fractures (CIRM is funding work on that) and now researchers at Duke Health believe they have figured out how that works.

The research, published in the journal Nature Communications, identifies what the Duke team call the “youth factor” inside bone marrow stem cells. It’s a type of white blood cell called a macrophage. They say the proteins these macrophages produce help stimulate bone repair.

In a news story in Medicine News Line  Benjamin Alman, senior author on the study, says:

“While macrophages are known to play a role in repair and regeneration, prior studies do not identify secreted factors responsible for the effect. Here we show that young macrophage cells play a role in the rejuvenation process, and injection of one of the factors produced by the young cells into a fracture in old mice rejuvenates the pace of repair. This suggests a new therapeutic approach to fracture rejuvenation.”

Next step, testing this in people.

A new way to track stem cells in the body

It’s one thing to transplant stem cells into a person’s body. It’s another to know that they are going to go where you want them to and do what you want them to. University of Washington researchers have invented a device that doesn’t just track where the cells end up, but also what happens to them along the way.

The device is called “CellTagging”, and in an article in Health Medicine Network, Samantha Morris, one of the lead researchers says this could help in better understanding how to use stem cells to grow replacement tissues and organs.

“There is a lot of interest in the potential of regenerative medicine — growing tissues and organs in labs — to test new drugs, for example, or for transplants one day. But we need to understand how the reprogramming process works. We want to know if the process for converting skin cells to heart cells is the same as for liver cells or brain cells. What are the special conditions necessary to turn one cell type into any other cell type? We designed this tool to help answer these questions.”

In the study, published in the journal Nature, the researchers explain how they use a virus to insert tiny DNA “barcodes” into cells and that as the cells travel through the body they are able to track them.

Morris says this could help scientists better understand the conditions needed to more effectively program cells to do what we want them to.

“Right now, cell reprogramming is really inefficient. When you take one cell population, such as skin cells, and turn it into a different cell population — say intestinal cells — only about 1 percent of cells successfully reprogram. And because it’s such a rare event, scientists have thought it is likely to be a random process — there is some correct set of steps that a few cells randomly hit upon. We found the exact opposite. Our technology lets us see that if a cell starts down the right path to reprogramming very early in the process, all of its related sibling cells and their descendants are on the same page, doing the same thing.”