Human Odontoma-Derived Cells with Neural Stem Cell and Regenerative Properties

Objective: Post-natal stem cells isolated from dental pulp, periodontal ligament, Hertwig root sheath, exfoliated deciduous teeth and cementum still have limited dental regenerative properties. Complications associated with tooth-loss underscore the need for dental stem cells capable of regenerating all major tooth components including enamel, dentin, cementum and pulp tissue. These unique progenitor cells may reside in odontoma, a developmental malformations that contains normal dental tissues and undifferentiated cells in a disorganized fashion. We tested the hypothesis that human odontoma contains post-natal stem cells that commit readily to dental differentiation and retain the capacity to regenerate major dental tissues.

Methods: A group of complex odontomas were obtained from a 7 year-old female patient after written informed consent. The odontomas were broken to granules, digested with collagenase and seeded in culture using DMEM/Ham's F-12 supplemented with 100 U/ml penicillin, 100 mg/ml streptomycin sulfate, 25 µg/ml sodium L-ascorbate and 10% fetal bovine serum. Primary human odontoma-derived cells (HODCs) emerging from the odontoma granules were expanded in culture and further characterized to assess proliferative capacity and neural stem cell immunophenotype. In vivo regenerative capacity was assessed by transplanting HODCs attached to hydroxyapatite/tricalcium phosphate (HA/TCP) into immunocompromised mice or the transplantation of HODC attached to biodegradable polycaprolactone (PCL) placed in tooth root canals.

Results: HODCs were highly proliferative, expressed telomerase and neural stem cell markers that include nestin, Sox 2 and ß-tubulin. The composite of HODCs- HA/TCP transplanted into immunocompromised mice regenerated cementum-like hard tissues while a composite of HODCs-PCL packed into tooth root canals before transplantation regenerated new dentin. Newly formed dentin contained numerous dentinal tubules and an apparent dentin-pulp arrangement.

Conclusions: HODCs represent a unique population of neural crest-derived odontogenic progenitor cells. Outcome of in vivo differentiation is affected by choice of ceramic carrier (Supported by DHHS/NIH/NCI grant 5K08CA120875-02).