J Korean Assoc Maxillofac Plast Reconstr Surg.  2007 Jul;29(4):279-288.

Evaluation of osteogenic activity and mineralization of cultured human dental papilla-derived cells

• Park BW
• Byun JH
• Choi MJ
• Hah YS
• Kim DR
• Cho YC
• Sung IY
• Kim JR

Abstract

In the present study, we focused on stem cells in the dental papilla of the tooth germ. The tooth germ, sometimes called the tooth bud, is the primordial structure from which a tooth is formed. The tooth germ consists of the enamel organ, the dental papilla, and the dental follicle. The dental papilla lies below a cellular aggregation of the enamel organ. Mesenchymal cells within the dental papilla are responsible for formation of dentin and pulp of a tooth. Tooth germ disappears as a tooth is formed, but that of a third molar stays in the jawbone of a human until the age of 10 to 16, because third molars grow slowly. Impacted third molar tooth germs from young adults are sometimes extracted for orthodontic treatment. In the present study, we evaluated the osteogenic activity and mineralization of cultured human dental papilla-derived cells. Dental papillas were harvested from mandible during surgical extraction of lower impacted third molar from 3 patients aged 13-15 years. After passage 3, the dental papilladerived cells were trypsinized and subsequently suspended in the osteogenic induction DMEM medium supplemented with 10% fetal bovine serum, 50 g/ml L-ascorbic acid 2-phosphate, 10 nM dexamethasone and 10 mM -glycerophosphate at a density of 1 x 10(6) cells/dish in a 100-mm culture dish. The dental papilla-derived cells were then cultured for 6 weeks and the medium was changes every 3 days during the incubation period. Dental papilla-derived cells showed positive alkaline phosphatase (ALP) staining during 42 days of culture period. The formation of ALP stain showed its maximal manifestation at day 7 of culture period, then decreased in intensity during the culture period. ALP mRNA level was largely elevated at 1 weeks and gradually decreased with culture time. Osteocalcin mRNA expression appeared at day 14 in culture, after that its expression continuously increased in a time-dependent manner up to day 28. The expression remained constant thereafter. Runx2 expression appeared at day 7 with no detection thereafter. Von Kossa-positive mineralization nodules were first present at day 14 in culture followed by an increased number of positive nodules during the entire duration of the culture period. Osteocalcin secretion was detectable in the culture medium from 1 week. The secretion of osteocalcin from dental papilla-derived cells into the medium greatly increased after 3 weeks although it showed a shallow increase by then. In conclusion, our study showed that cultured human dental papilla-derived cells differentiated into active osteoblastic cells that were involved in synthesis of bone matrix and the subsequent mineralization of the matrix.

Keyword

Dental papilla-derived cell; Osteoblastic differentiation; Mineralization

MeSH Terms

Alkaline Phosphatase
Ascorbic Acid
Bone Matrix
Dental Papilla
Dental Sac
Dentin
Dexamethasone
Enamel Organ
Humans*
Mandible
Molar, Third
Osteoblasts
Osteocalcin
RNA, Messenger
Stem Cells
Tooth
Tooth Germ
Trypsin
Young Adult
Alkaline Phosphatase
Ascorbic Acid
Dexamethasone
Osteocalcin
RNA, Messenger
Trypsin