A research group from the University of Southern California (USC) School of Dentistry have identified a new stem cell population that is responsible for a particular birth defect and might someday help treat wounded soldiers, accident victims and other patients recover from disfiguring facial injuries.
“This has a lot more implication than what we initially thought,” said Yang Chai, a lead researcher on the study at the Herman Ostrow School of Dentistry of USC. “We can take advantage of these stem cells not only to repair a birth defect, but to provide facial regeneration for veterans or other people who have suffered traumatic injury.”
According to Chai, treatments of human patients that utilize the new stem cell population he and his colleagues identified could become available within the next five to 10 years, but it must pass through the intense hurdles of clinical trials with human patients.
In their mouse studies, Chai and his team noticed a stem cell population that expresses the transcription factor Gli1+. These Gli1+ stem cells appear within the tissues that eventually fuse the craniofacial bones together. However, in mice that have a shortage or even absence of the Gli1+ stem cells, the skull bones prematurely fused together to cause “craniosynostosis,” a birth defect that locks the skull into a small structure can cannot accommodate the growing brain and can hinder brain development. Chai and his colleagues also found that these Gli+ stem cells are activated when the skull is injured. Therefore, they transplanted Gli1+ stem cells into injured mice, and within weeks, it was clear that the Gli1+ stem cells had migrated to the injured parts of the skull and were repairing those damaged areas.
“It is a very minimal procedure to just cut off a strip of bone instead of cutting the entire calvaria [skull-cap],” Chai said. A stem cell treatment “will truly restore the normal anatomy, which will then be able to respond to the continuous brain growth and the patient can live a normal life.”
These findings also have upset the bone development apple cart, according to Hu Zhao, the first author of this publication. “Before our findings, people just assumed the bones all around the body are the same,” Zhao said. “We are now showing that they are all totally different, that they have a different source of stem cells and a different healing mechanism.”
The discovery of these Gli1+ stem cells and their ability to regenerate craniofacial injuries might mean that physicians will be able to use them to treat people who have suffered disfiguring facial injuries and infants diagnosed with craniosynostosis through biological means instead of multiple, high-risk surgeries.
Presently, the surgeons, unknowingly, were destroying the regenerative stem cells that could potentially help the patient when they operated on craniosynostosis patients. During a typical craniosynostosis surgery, doctors break the skull into multiple pieces, staple them together and then discard the suture tissues as waste. Zhao said the procedure, intended to aid brain growth, actually interferes with healing because the Gli1+ stem cells are lost.
According to Chai, a biological approach that transplants Gli1+ stem cells into targeted areas could give infants with craniosynostosis the flexibility that they need for their brains to grow normally. For those patients who have suffered head trauma or facial disfigurement, the Gli1+ stem cells could repair fractured or injured areas.
Chai acknowledges the need to conduct additional experiments before such a treatment is tested in clinical trials with patients.
“One of our ideas is that we could probably use those healthy sutures and the healthy pieces from them and transplant them on the injured sides,” Zhao said.