Research Article

Human Cell (2011) 24:43–50 DOI 10.1007/s13577-011-0010-7

RESEARCH ARTICLE

Dentinogenic potential of human adult dental pulp cells during the extended primary culture
Jin-Hee Min • Seon-Yle Ko • Yong-Bum Cho Chun-Jeih Ryu • Young-Joo Jang
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Received: 22 November 2010 / Accepted: 19 December 2010 / Published online: 22 February 2011 Ó Japan Human Cell Society and Springer 2011Abstract Despite the frequent use of primary dental pulp cells in dental regenerative research, few systematic studies of stemness for osteogenic and dentinogenic differentiation of human adult pulp cells have been reported. To investigate the stemness of human adult dental pulp cells, pulp tissues were obtained from extracted third molars and used as a source of pulp cells. In FACS analysis andimmunophenotyping, the general mesenchymal stem cell markers CD44, CD90, and CD146 were highly expressed in early passages of the pulp cell culture. The stem cell population was dramatically decreased in an expansion culture of human dental pulp cells. When pulp cells were treated with additives such as b-glycerophosphate, ascorbic acid, and dexamethasone, nodule formation was facilitated andmineralization occurred within 2 weeks. Expression of osteogenic markers such as alkaline phosphatase, osteocalcin, and osteonectin was relatively low in undifferentiated cells, but increased significantly under differentiation conditions in whole passages. Dentinogenic markers such as dentin sialophosphoprotein and dentin matrix protein-1

appeared to decrease in their expression with increasing passagenumber; however, peak levels of expression occurred at around passage 5. These data suggested that stem cells with differentiation potential might exist in the dental pulp primary culture, and that their phenotypes were changed during expansion culture over 8–9 passages. Under these conditions, a dentinogenic population of pulp cells occurred in limited early passages, whereas osteogenic cellsoccurred throughout the whole passage range. Keywords Human dental pulp cells Á Dentinogenic progenitors Á Adult stem cells Á Differentiation

Introduction Tissues in our body contain the potential for tissue-specific regeneration. For example, in the case of skin epithelium, tissue injuries are repaired and regenerated into normal tissue without restriction. Bone and connective tissues only showrestricted regeneration for very limited types of injuries. On the other hand, the regeneration process is not induced in nerve and cardiac tissues; therefore, even a very small amount of damage to these tissues can be lethal. Proper regeneration occurs in tissue-specific stem cells, which have a strong capacity for both cell proliferation and tissue-specific differentiation. Therefore, theoretically,tissue regeneration using stem cells will be a more effective therapeutic method than any other remedial strategy for the treatment of damaged tissues. However, serious problems still need to be solved, including where to obtain usable stem cells in the human body, and how to get a sufficient amount of cells to achieve complete tissue regeneration [1]. Theoretically, stem cells exist everywhere inour body, but

J.-H. Min and S.-Y. Ko contributed equally to this work. J.-H. Min Á Y.-J. Jang (&) World Class University Research Department of Nanobiomedical Science, Institute of Tissue Regeneration Engineering, Dankook University, 29 Anseo-Dong, Cheonan 330-714, Korea e-mail: yjjang@dankook.ac.kr S.-Y. Ko Á Y.-B. Cho Á Y.-J. Jang The School of Dentistry, Dankook University, 29 Anseo-Dong,Cheonan 330-714, Korea C.-J. Ryu Department of Bioscience and Biotechnology, Sejong University, 98 Gunja-Dong, Seoul 143-747, Korea

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recognizing and accessing the regions containing these cells so that they can be captured through surgery is a difficult task. Even when it is possible, surgery aimed at collecting cells can cause defects in normal tissues. However,...