Establishment of an Oronasal Fistula Mice Model

Our research has focused on how to establish the stable and standardized mouse model of oronasal fistula. This protocol has also demonstrated the body weight changes, all size changes, and the histologic features of the oronasal fistula formation. The current experimental changes of establishing oronasal fistula models are the mice mortality by suffocation or blood loss, as well as the standardization of the wound size.

Our protocol significantly reduces the amount of bleeding in mice during surgery, relative to the traditional use of a biopsy punch. This reduces the risk of suffocation due to severe bleeding. Additionally, our experimental method is also simpler and less technically sensitive.

Our future research aims to focus on observing the inflammatory response during oronasal fistula formation. We also plan on developing novel strategies to reduce the inflammatory response while promoting palate wound healing to reduce the incidence of oronasal fistula. Begin by securing an anesthetized female mouse to a foam board covered with sterile sheets.

Then carefully tape the mouse in a supine position to a surgical platform. Position two needles in front of the orbital-ear plane. Place two more needles behind it.

Next place a rubber band around the needles and cross the incisors to hold the mouth open. Use microsurgical tweezers to prop open the corners of the mouth. Proceed to retrieve the heated ophthalmologic cautery.

Now position the cautery tip one millimeter from the midline intersection of the palate and first premolar to create a full thickness mucosal injury to the hard palate. Remove the cautery when the mucosa around the tip turns white. Heat the ophthalmologic cautery to 250 degrees Celsius in the Germinator for 10 minutes.

Then place it on the hard palate and enlarge the wound around the edges. Finally, use microsurgical scissors to excise any excess denatured soft tissue surrounding the wound. Afterward, apply sterile cotton to stop bleeding and prevent inhalation asphyxiation in the mouse.

Notable variability was observed in the size of the generated oronasal fistula. The wound size showed a significant variation on the seventh day post-surgery. A significant reduction in the body weights of the mice was also observed on day seven, which is approximately 25%Histological analysis of the oronasal fistula revealed a loss of hard palate mucosa, denuded bone, and oronasal fistula formation.