Hypophosphatasia-associated Deficiencies in Mineralization and Gene Expression in Cultured Dental Pulp Cells Obtained from Human Teeth

详细信息    查看全文

• 作者：Thaisâ ; ngela L. Rodrigues ; DDS ; MS ; PhD^&lowast ; ; Brian L. Foster ; MS ; PhD^&dagger ; ; Karina G. Silverio ; DDS ; MS ; PhD^&lowast ; ; Luciane Martins ; BS ; MS ; PhD^&lowast ; ; Marcio Z. Casati ; DDS ; MS ; PhD^&lowast ; ; Enilson A. Sallum ; DDS ; MS ; PhD^&lowast ; ; Martha J. Somerman ; DDS ; PhD^&dagger ; ; Francisco H. Nociti Jr. ; DDS ; MS ; PhD^&lowast ; ; ^&dagger ; ; ^{nociti@fop.unicamp.br" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Alkaline phosphatase ; dental pulp cells ; dentin ; hypophosphatasia ; pyrophosphate
• 刊名：Journal of Endodontics
• 出版年：2012
• 出版时间：July 2012
• 年：2012
• 卷：38
• 期：7
• 页码：907-912
• 全文大小：435 K

文摘

Mutations in the gene ALPL in hypophosphatasia (HPP) reduce the function of tissue nonspecific alkaline phosphatase, and the resulting increase in pyrophosphate (PP_i) contributes to bone and tooth mineralization defects by inhibiting physiologic calcium-phosphate (P_i) precipitation. Although periodontal phenotypes are well documented, pulp/dentin abnormalities have been suggested in the clinical literature although reports are variable and underlying mechanisms remains unclear. In vitro analyses were used to identify mechanisms involved in HPP-associated pulp/dentin phenotypes.

Methods

Primary pulp cells cultured from HPP subjects were established to assay alkaline phosphatase (ALP) activity, mineralization, and gene expression compared with cells from healthy controls. Exogenous P_i was provided to the correct P_i/PP_i ratio in cell culture.

Results

HPP cells exhibited significantly reduced ALP activity (by 50%) and mineral nodule formation (by 60%) compared with the controls. The expression of PP_i regulatory genes was altered in HPP pulp cells, including reduction in the progressive ankylosis gene (ANKH) and increased ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Odontoblast marker gene expression was disrupted in HPP cells, including reduced osteopontin (OPN), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP), and matrix extracellular phosphoprotein (MEPE). The addition of P_i provided a corrective measure for mineralization and partially rescued the expression of some genes although cells retained altered messenger RNA levels for PP_i-associated genes.

Conclusions

These studies suggest that under HPP conditions pulp cells have the compromised ability to mineralize and feature a disrupted odontoblast profile, providing a first step toward understanding the molecular mechanisms for dentin phenotypes observed in HPP.