Regenerating bone: Injectable biomaterials may be on the horizon

Patients in need of dental implants often face a shared dilemma: lack of sufficient bone to support their implants. Current options to regenerate bone range from the invasive — using surgery to graft bone from other parts of the body — to minimally invasive, through the use of hydrogels.

The work of Texas A&M University Baylor College of Dentistry researcher Xiaohua Liu, Ph.D., could expand options for patients with a new type of injectable biomaterial that initiates bone regeneration. While the end goal is essentially the same as current minimally invasive methods, the material and the process are strikingly different. Compared with commercial hydrogels, which often utilize animal-derived proteins, preliminary test results indicate that the synthetic material Liu is developing may be more effective at filling irregularities and defects in craniofacial bone.

An article published in Advanced Healthcare Materials in October details the mechanism: A nanofibrous porous scaffolding — picture a tiny sphere — houses proteins that initiate bone regeneration from a patient’s own cells. Trapped within the nanosphere is a growth factor known as BMP2, or bone morphogenetic protein. This is released in specific amounts at controlled intervals to help bone tissue differentiate. As a cell inside the once porous sphere grows, the nanofibrous scaffolding slowly disintegrates, and a new bone cell is born.

“We want to use bioengineering to mimic the natural tissues. This is entirely synthetic, but it promotes growth from within your own body,” says Liu, who explains another advantage to the material. “When using materials from animals, we still have some concern about the immune response. Using synthetic materials, you don’t have that concern. The immune response will be different.”

A two-year, $210,000 grant from the National Institutes of Health – National Institute of Dental and Craniofacial Research in 2013 gave Liu the resources he needed to develop this new injectable system using the nanofibrous microsphere. With a one-year extension until June 2016, the success of subsequent testing means the injectable material could soon proceed to clinical trials. One intended end result: use in a nonsurgical version of a maxillary sinus lift, which increases the amount of bone in the upper jaw prior to placing dental implants.

Liu’s research is part of a larger trend.

Thomas Diekwisch, D.M.D., Ph.D., director of the college’s Center for Craniofacial Research and Diagnosis and chair of the Department of Periodontics, says studies such as this one are on the rise.

“Biological scaffold design has been an area of exponential growth during the recent decade,” says Diekwisch. “TAMBCD is fortunate to have experts in this field of the caliber of Dr. Xiaohua Liu, who are able to apply this technology toward craniofacial applications.”

LauraLee Hughes, executive director in the Office of Technology Translation at Texas A&M Health Science Center, has worked with Liu on commercial development for another product, a novel bioadhesive patch designed to treat canker sores. She offers one explanation for the shift toward technologies that rely on the body to regenerate tissues.

“Scaffold technologies, such as what has been developed by Dr. Liu to promote regeneration of a patient’s own cells, offer the promise of being able to more fully restore the biological function of a particular tissue or bone,” says Hughes. “The potential for this type of technology is huge. If the science around these types of technologies can be advanced to demonstrate safety and reproducibility in humans, it could broadly be applied to regenerative strategies for other types of tissues and biological materials.”