Studies On The Effects Of EMPs On Proliferation And Differentiation Of SHED In Vitro

Backgrounds: Tooth development involves a series of critical, sequential reciprocalinteractions between the oral epithelium and cranial neural crest-derived mesenchymal cells.Studies have demonstrated the influence of the primary epithelial band in the induction oftooth development and such interactions, involving a highly co-ordinated expression ofgrowth factors, homeobox genes and transcription factors, progressively lead to thedevelopment of the tooth primordia into a complex mineralized structure of specific size,shape and location within the dental arch. Studies using a genetic marker to follow neuralcrest cell migration and differentiation in the mouse have clearly demonstrated that in thedeveloping tooth germ, cranial neural crest derived ectomesenchyme contributes to thecondensed dental ectomesenchyme during the bud stage and subsequently to the formation ofthe dental papilla and surrounding dental follicle. Such studies have also demonstrated thatodontoblasts, dentine matrix and much of the pulpal tissue are of cranial neural crest origin.Mechanisms that contribute to dental injury include induction of apoptosis, activation ofimmune responses, and alterations in dental tissue physiology. Under most circumstances,clearance of apoptotic cells occurs with remarkable rapidity, without eliciting aninflammatory response.The mechanism of tooth tissue reconstruction is similar to the processof tooth development. A structural remodeling of the pulp chamber takes place during toothrepair with reparative dentin deposition. Apoptosis is significantly higher in the odontoblasticlayer than in the rest of the pulp. It is possible that the elimination of odontoblasts byapoptosis may produce death signals, leading to the simultaneous elimination of theneighboring progenitor cells.Upon injury, stem cells are recruited from remote storage sites toareas of wound healing, where they are engrafted in high numbers. Elimination ofodontoblasts and the neighboring odontoblast progenitors by apoptosis will elicit migrationof an important number of DPSCs to the injury site, where they will differentiate intoodontoblast-like cells, thus ensuring the regenerative capacity of the pulp. Objective: To investigate the effect of EMPs on proliferation and differentiation ofSHED in vitro. Methods: The stem cells were collected from human exfoliated dediduousteeth by Enzyme digestion and Tissue explant method.We separated EMPs from bovine teethwith acetic acid method.The proliferation activity was examed by MTT assay. ALP andDSPP,DMP-1mRNA was analyzed to exam the differentiation activity after inducement.Results: The stem cells from human exfoliated dediduous teeth showed colony growth andhave the ability of certain self renewal. EMPs have no effect on cell proliferation, but cansignificantly improve the ALP activity and showed a dose-dependent manner. And that, theexpression of DSPP and DMP1mRNA in effected cells increased. Conclusion: EMPs play apositive role in the differentiation of SHED to dentin-like cells.