Protein drugs, which derive from biological sources, represent some of the most important and effective biopharmaceuticals on the market. Some, like insulin, have been used for decades, while many more based on cloned genes are coming to market and are valued for their precise and powerful functions.

Yet the field of dental medicine has very few such drugs due to their high costs, and the ones that are used are delivered invasively, often through surgical procedures, to gum tissues.

Now, a report by University of Pennsylvania School of Dental Medicine scientists in the journal Biomaterials suggests a new approach for delivering a protein drug to treat and prevent oral diseases, including dental caries, commonly known as cavities. Using plants to produce antimicrobial peptides, the researchers were able to rapidly kill tooth-decay-causing bacteria and thwart their ability to form biofilms on a tooth-like surface with a single topical treatment. The peptides were even more effective when combined with an enzyme that degrades the matrix, which surrounds and protects bacteria residing inside biofilms.



In addition, the researchers demonstrated that these peptides, produced in a cost-effective manner in plants, could be taken up by periodontal and gingival cells, indicating that this novel delivery method could be useful in treating diseases that affect the gum tissues, perhaps by promoting wound healing or bone regeneration. The platform is low-cost compared to the current means of producing biopharmaceuticals and presents a unique opportunity to develop an affordable therapeutic approach that simultaneously attacks disease-causing plaque and promotes gum health, the researchers said.

"As scientists we have many opportunities to develop breakthrough treatments but cost is a huge obstacle," said Hyun (Michel) Koo, co-corresponding author on the study and professor in the Department of Orthodontics and divisions of Pediatric Dentistry and Community Oral Health in Penn Dental Medicine. "What makes this approach so exciting is not only the science but, because the production costs are low, the feasibility of getting the therapy to the population who truly needs yet can't afford it."

The work arose from a partnership between Koo and co-corresponding author Henry Daniell, director of translational research and professor in Penn Dental Medicine's Department of Biochemistry. Koo was aware of Daniell's groundbreaking plant-produced therapeutics for a number of important human infectious and inherited diseases. And Daniell learned that Koo had done extensive work on caries-causing biofilms, including searching for alternative approaches to degrade them or prevent them altogether.