RESUMEN
The dental follicle is a mesenchymal tissue that surrounds the developing tooth germ. During tooth root formation, periodontal components, viz., cementum, periodontal ligament (PDL), and alveolar bone, are created by dental follicle progenitors. Here, we report the presence of PDL progenitors in mouse dental follicle (MDF) cells. MDF cells were obtained from mouse incisor tooth germs and immortalized by the expression of a mutant human papilloma virus type 16 E6 gene lacking the PDZ-domain-binding motif. MDF cells expressing the mutant E6 gene (MDF( E6-EGFP ) cells) had an extended life span, beyond 150 population doublings (PD). In contrast, normal MDF cells failed to proliferate beyond 10 PD. MDF( E6-EGFP ) cells expressed tendon/ligament phenotype-related genes such as Scleraxis (Scx), growth and differentiation factor-5, EphA4, Six-1, and type I collagen. In addition, the expression of periostin was observed. To elucidate the differentiation capacity of MDF( E6-EGFP ) cells in vivo, the cells were transplanted into severe combined immunodeficiency mice. At 4 weeks, MDF( E6-EGFP ) cell transplants had the capacity to generate a PDL-like tissue that expressed periostin, Scx, and type XII collagen and the fibrillar assembly of type I collagen. Our findings suggest that MDF( E6-EGFP ) cells can act as PDL progenitors, and that these cells may be a useful research tool for studying PDL formation and for developing regeneration therapies.
Asunto(s)
Saco Dental/citología , Células Madre Mesenquimatosas/citología , Ligamento Periodontal/citología , Fosfatasa Alcalina/metabolismo , Animales , Animales Recién Nacidos , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Proteínas Morfogenéticas Óseas/genética , Moléculas de Adhesión Celular/genética , Diferenciación Celular/genética , Diferenciación Celular/fisiología , Línea Celular Transformada , Colágeno Tipo I/genética , Colágeno Tipo XII/genética , Saco Dental/metabolismo , Expresión Génica , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Factor 5 de Diferenciación de Crecimiento , Incisivo/citología , Incisivo/metabolismo , Masculino , Células Madre Mesenquimatosas/metabolismo , Ratones , Ratones Endogámicos ICR , Ratones SCID , Proteínas Oncogénicas Virales/genética , Osteocalcina/genética , Osteopontina/genética , Ligamento Periodontal/metabolismo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Represoras/genéticaRESUMEN
The purpose of this study is the objective and quantitative evaluation of masticatory laterality and its daily variability. Various foods with different textures were used to investigate whether food texture influenced masticatory laterality. Ten healthy subjects and seven foods were used. Recordings of chewing movements were repeated three times at intervals of 1 week. Masticatory laterality was assessed with an Asymmetry Index [AI: (number of right side strokes - number of left side strokes)/number of total strokes]. Medians and ranges of the three recordings were calculated. The observed AI ranges in the three trials were limited with the exception of two subjects. Among the other subjects, averages of the absolute values of the medians were from 32.5 to 73.4%. Statistically significant differences between the hardest food and softer foods were observed in absolute value of AI medians. Masticatory laterality could be evaluated by an AI. Eight of 10 subjects showed limited ranges of AI in three recordings. It should be noted that a few people actually chew on either side but might chew on one side only on a particular day. Hard food evoked more masticatory laterality, and seemed more appropriate for laterality examinations.
