Therapy Regenerates Bone Without Adding Cells

Richard Gawel
Photo by Jerry Mastey, University of Michigan.


Photo by Jerry Mastey, University of Michigan.

When patients lose bone, doctors typically use metallic alloys or harvested bone tissue to replace it. Yet these materials often lack biological function or risk rejection. Alternative bone regeneration techniques rely on added cells, though these processes may affect the added cells’ bone-forming abilities or even turn them into tumors.

Scientists at the University of Michigan are exploring another approach: activating the regenerative capacities of the patient’s existing cells instead of using externally added cells. The research is focusing on microRNAs, which have been recognized as cell regulators but so far have not been used to successfully regenerate tissues.

“The new technology we have been working on opens doors for new therapies using DNA and RNA in regenerative medicine and boosts the possibility of dealing with other challenging human diseases,” said Peter X. Ma, one of the researchers, the Richard H. Kingery collegiate professor of dentistry and a professor of biomedical engineering, macromolecular science and engineering, and materials science and engineering.

MicroRNAs can’t enter cells easily. They also are unstable in vivo, and they’re difficult to introduce into desired sites. The researchers, though, have developed a biodegradable polymer that can self-assemble into very stable and efficient vehicles to transport a microRNA into cells. This achieves controllable long-term release of the microRNA-loaded vehicle to enter a patient’s cells and localize the microRNA in a 3-D scaffold.

Made from biomaterials, the scaffold supports bone regeneration, so no added cells are necessary. So far, this strategy has regulated multiple bone-forming genes and fully regenerated critical-sized bone defects in osteoporotic mice. The researchers now are investigating large animals and evaluating potential human use.

The study, “Cell-Free 3D Scaffold with Two-Stage Deliver of miRNA-26a to Regenerate Critical Sized Bone Defects,” was published by Nature Communications. It was written by Ma and by Xiaojin Zhang, Yan Li, Eugene Chen, and Jihua Chen.

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