Characterization of mesenchymal progenitor cell populations from non-epithelial oral mucosa.

OBJECTIVES: The characteristics of cell populations extracted from oral mucosal non-epithelial tissues and their ability to differentiate were evaluated in vitro as a potential source of cells for mandibular and corneal regeneration. MATERIALS AND METHODS: Oral mucosal non-epithelial cells (OMNECs) were extracted from tissue samples and were studied by flow cytometry and RT-PCR. Cells differentiating into osteoblasts, adipocytes, chondrocytes, neurocytes, or keratocytes were characterized by RT-PCR and cell staining. RESULTS: OMNECs expressed CD44, CD90, CD105, CD166, and STRO-1 antigens, which are markers for mesenchymal stem cells. In addition, Oct3/4, c-Myc, Nanog, KLF4, and Rex, which are expressed by embryonic or pluripotent stem cells, were detected by RT-PCR. Expression of CD49d, CD56, and PDGFRα, proteins closely associated with the neural crest, was observed in OMNECs, as was expression of Twist1, Sox9, Snail1 and Snail2, which are early neural crest and neural markers. Specific differentiation markers were expressed in OMNECs after differentiation into osteoblasts, adipocytes, chondrocytes, or keratocytes. CONCLUSIONS: Populations of OMNECs may contain both mesenchymal stem cells and neural crest origin cells and are a potential cell source for autologous regeneration of mandibular or corneal stroma.

Biomechanical three-dimensional finite-element analysis of maxillary prostheses with implants. Design of number and position of implants for maxillary prostheses after hemimaxillectomy.

The present study analyzed stress distributions in craniofacial structures around implant-supported maxillary prostheses. Using post-hemimaxillectomy computed tomography (CT) of a patient, the authors constructed a three-dimensional (3D) solid model using Digital Imaging and Communications in Medicine data (DICOM data) for maxillofacial and cranial bones. The effects of different prosthesis designs on stress distributions in craniofacial bones and osseous tissues around the implants were biomechanically investigated using 3D finite-element analysis. Maxillary prostheses were designed with 2 implants in the zygoma on the affected side and 2-3 implants in the maxillary alveolar bone on the unaffected side, without using a cantilever. Zygomatic implants provided suitable stress dispersal to the zygomatic and craniofacial bones on the affected side. This information is useful for designing maxillary prostheses.

Isolation of oral epithelial progenitors using collagen IV.

OBJECTIVE: Although oral mucosal epithelial stem cells are thought to reside in the basal layer, such cells have not yet been isolated. We isolated a population of rabbit oral epithelial progenitor cells containing putative stem cells. MATERIALS AND METHODS: Epithelial cells harvested from rabbit buccal mucosa were allowed to adhere to dishes coated with collagen IV for periods ranging from 10 min to 16 h. The properties of individual cell populations were evaluated using BrdU, Ki-67, integrin beta1, integrin alpha6 and keratin 13 using colony forming efficiency (CFE). RESULTS: Cells that adhered to collagen IV-coated dishes within 10 min were enriched about sixfold in terms of BrdU incorporation, Ki-67, integrin alpha6 and integrin beta1 were strongly expressed. Interestingly, keratin 13 was faintly expressed. The CFE of rapidly adherent cells among oral epithelial cells was significant compared with other cell populations. CONCLUSIONS: These results suggested that rabbit oral epithelial cells could be isolated by depending on adhesiveness to collagen IV, especially when segregated according to progenitor cell properties. Putative progenitor cells with stem cell properties were most effectively harvested within 10 min. Our separation procedure should be a useful tool with which to isolate epithelial stem cells for regenerative medicine.

Three-dimensional finite elemental analysis of zygomatic implants in craniofacial structures.

The objective of this study was to analyse stress distribution in craniofacial structures around zygomatic osseointegrated implants. An integrated system for Digital Imaging and Communications in Medicine (DICOM) data were utilized to create a three-dimensional model of craniofacial structures. The amount and distribution of the main stresses were compared using three-dimensional finite elemental analysis. The system allowed visual confirmation and analysis of stress distribution as well as the convenient and simple construction of a digital biomechanical model that provided details of anatomical structures in the regions of interest. Zygomatic implants with or without connected implants supporting the superstructure were compared. Stresses in severely resorbed maxillae with connected implants were not concentrated around the alveolar bone supporting the zygomatic implants. Stresses where there were no connected implants tended to be generated in the zygomatic bone, at the middle part of the zygomatic implant and at the joint of the fixture-abutment. Stress due to occlusal forces is mainly supported by the zygomatic bone, is transferred predominantly through the infrazygomatic crest, and is divided between the frontal and temporal processes of the zygomatic bone in different directions.

Use of the buccal fat pad as a pedicle graft.

A technique was developed to use the pedicle buccal fat pad as method for closing an oro-antral communication. The buccal fat pad is situated in the posterior part of the maxilla and bounded by the pterygopalatine fossa, buccal muscle, and masseter muscle. It is supplied by blood from small branches of the maxillary artery, the superficial temporal artery, and the facial artery. Generally, the buccal fat pad can be easily reached by a horizontal incision over the periosteum near the maxillary third molar. As much as 60 x 50mm2 can be obtained. For reconstructive surgery, the buccal fat pad is suitable for closing the sinus near the hard and soft palate and naso-oral fistulae. In our case, graft tissues after surgery healed satisfactorily, began to epithelialize at two weeks after operation, and appeared with normal mucous-like changes at about one month. Thus, the pedicle buccal fat pad is a safe, simple, convenient, and effective grafting method, if it is applied to appropriate cases.

Microvascular free tissue transfer in oral and maxillofacial reconstruction.

Forty-two patients with head and neck cancer were submitted to microvascular reconstructive procedures. We divided patients in three groups; a first group of 30 patients, in whom the oral floor (8 patients), the part of tongue (14 patients), the lower gingiva (6 patients) and the oropharynx (2 patients) were reconstructed using various sizes of forearm flaps; a second group of 7 patients who underwent buccal mucosa reconstructions with the forearm flaps; and a third group of 5 patients who received rectus abdominis flaps for total tongue reconstruction. Three illustrative cases, one from each group, are presented in detail. Good results were obtained in 39 patients (94%), with both functional and morphological rehabilitation. There were three flap losses due to thrombosis of the microvascular anastomoses. There was no surgical mortality. The average operating time was about 10 hours in total. We concluded that there is a place for these complex procedures in the treatment of selected cases of head and neck tumors.