Comparison between osteoblasts derived from human dental pulp stem cells and osteosarcoma cell lines Annalisa Palmieri a , Furio Pezzetti a , Antonio Graziano b , D’Aquino Riccardo b , Ilaria Zollino c , Giorgio Brunelli c , Marcella Martinelli a , Marzia Arlotti a , Francesco Carinci c, * a Centre of Molecular Genetics, CARISBO Foundation, Institute of Histology and General Embryology, School of Medicine, University of Bologna, Bologna, Italy b Dental Clinic, Second University of Naples, Naples, Italy c Chair of Maxillofacial Surgery, School of Medicine, University of Ferrara, Arcispedale S. Anna, Corso Giovecca 203, 44100 Ferrara, Italy Received 18 October 2007; revised 14 December 2007; accepted 25 February 2008 Abstract Stem cells derived from human dental pulp are able to differentiate into osteoblasts and are a potential source of autologous bone. The aim of this study was to compare genes differentially expressed in osteoblastoids from human dental pulp (OHDP) to osteosarcoma cells (OCs). Human dental pulp was extracted and immersed in a digestive solution. Cells were cultured and selected using c-kit, CD34, CD45 and STRO- 1 antibodies. In parallel, two OCs (i.e., SAOS2 and TE85) were cultured. RNA was extracted from different populations of cells and cDNA was used for the hybridisation of human 19.2 K DNA microarrays. We identified several differences in gene expression between OHDP and OCs. Some down-regulated OHDP genes, such as RUNX1, MAP4K4 and PRDM2, are involved in bone development, cell motility and transcript regulation. Gene expression in OHDP is significantly different from that in OCs, suggesting differences in cell function and activity between these cells. Ó 2008 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved. Keywords: Stem cells; Dental pulp; Autologous bone; Microarray; Tumour 1. Introduction Stem cells derived from human dental pulp are able to differentiate into osteoblastoid cells and are a potential source of autologous bone produced in vitro (Laino et al., 2005, 2006a,b). A new and highly enriched population of stem cells derived from dental pulp of both deciduous and permanent teeth was isolated, cultured and successively selected using FACS (Laino et al., 2005, 2006a,b). Cells obtained from dental pulp were cul- tured and successively selected using a fluorescence activated cell sorter (FACS). Immunoreactivity profiles of the cultured cells were performed and specific antigens for the stromal stem cells c-kit, CD34 and CD45 were detected. Mesenchymal stem/progenitor cell populations that are c-kit- and CD34- positive and CD45 negative were isolated. These cells prolifer- ate extensively under standard culture conditions, have a long life span and maintain their multipotential capabilities for generations (Laino et al., 2006a,b; Papaccio et al., 2006). Osteoblasts derived from human pulp stem cells (ODHPS) express osteocalcin and flk-1 (VEGF-R2) (D’Aquino et al., 2007; Graziano et al., 2007a,b). Interestingly, endotheliocytes that form vessel walls and stem cells synergically differentiate into osteoblasts and endotheliocytes (D’Aquino et al., 2007) When ODHPS obtained in vitro were transplanted into immunocompromised rats, they generated a tissue structure with an integral blood supply similar to that of human adult bone (D’Aquino et al., 2007). Stem cells are of great interest for tissue regeneration, tissue-based clinical therapies and transplantation, but due to * Corresponding author. Tel./fax: þ39 0532 455582. E-mail address: crc@unife.it (F. Carinci). URL: http://www.carinci.org 1065-6995/$ - see front matter Ó 2008 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.cellbi.2008.02.003 Cell Biology International 32 (2008) 733e738 www.elsevier.com/locate/cellbi