To find out whether the scaffolds encourage bone formation, the researchers added human fat-derived stem cells taken during a liposuction procedure to scaffolds immersed in a nutritional broth lacking pro-bone ingredients.

After three weeks, cells grown on 70 percent bone powder scaffolds showed gene activity hundreds of times higher in three genes indicative of bone formation, compared to cells grown on pure PCL scaffolds. Cells on 30 percent bone powder scaffolds showed large but less impressive increases in the same genes.

After the scientists added the key ingredient beta-glycerophosphate to the cells' broth to enable their enzymes to deposit calcium, the primary mineral in bone, the cells on 30 percent scaffolds produced about 30 percent more calcium per cell, while those on 70 percent scaffolds produced more than twice as much calcium per cell, compared to those on pure PCL scaffolds.

Finally, the team tested their scaffolds in mice with relatively large holes in their skull bones made experimentally. Without intervention, the bone wounds were too large to heal. Mice that got scaffold implants laden with stem cells had new bone growth within the hole over the 12 weeks of the experiment. And CT scans showed that at least 50 percent more bone grew in scaffolds containing 30 or 70 percent bone powder, compared to those with pure PCL.

"In the broth experiments, the 70 percent scaffold encouraged bone formation much better than the 30 percent scaffold," says Grayson, "but the 30 percent scaffold is stronger. Since there wasn't a difference between the two scaffolds in healing the mouse skulls, we are investigating further to figure out which blend is best overall."

Although the use of "decellularized" cow bone has been FDA-approved for clinical use, in future studies, the researchers say, they hope to test bone powder made from human bone since it is more widely used clinically. They also want to experiment with the designs of the scaffolds' interior to make it less geometric and more natural. And they plan to test additives that encourage new blood vessels to infiltrate the scaffolds, which will be necessary for thicker bone implants to survive.

---

Story Source:

The above post is reprinted from materials provided by Johns Hopkins Medicine. Note: Materials may be edited for content and length.