Journal of Dental Research 1–10 © International & American Associations for Dental Research 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0022034515570316 jdr.sagepub.com Research Reports: Biological Introduction Although human neural stem cells and human embryonic stem cells could be used for cell therapies to treat neurodegenerative disorders, such as Parkinson and Alzheimer diseases, several technical and ethical difficulties have limited their use in human therapies (Martino and Pluchino 2006; Lees et al. 2009). Therefore, the improvement of different therapeutic strategies for the treatment of neurologic disease using adult stem cells, such as mesenchymal stem cells (MSCs), remains a practical alternative (Chamberlain et al. 2007; Uccelli et al. 2011). MSCs are multipotent stem cells that are capable of dif- ferentiating into multiple cell types (Herzog et al. 2003; Keating 2012). The in vitro growth of undifferentiated MSCs, followed by induction of neural cell differentiation and subse- quent transplantation, is one of the most relevant methods for cell therapy to treat neurodegenerative disease (Martino et al. 2010; Maltman et al. 2011). Although MSCs can be derived from all postnatal tissues, human bone marrow (BM) has been used as the major source of MSCs to treat neurodegenerative disease (Pal et al. 2009; Yan K et al. 2013). However, there are some limitations to the clinical use of BM-MSCs; namely, cell harvesting requires an invasive method of isolation, and the cells are not abundant. Recently, different laboratories have described the isolation of human MSCs with neural plasticity from many tissues, includ- ing umbilical cold matrix (Bieback et al. 2004), amniotic fluid (Yan ZJ et al. 2013), adipose tissue (Zuk et al. 2002), and den- tal pulp (hDP; Arthur et al. 2008). Dental-derived MSCs, particularly dental pulp stem cells (DPSCs), have become an attractive source of MSCs because of their abundant availability and faster proliferation as com- pared with BM-MSCs (Gronthos et al. 2000). Dental-derived MSCs are related to BM-MSCs and are easily accessible, mak- ing them an interesting alternative for cell therapies (Morsczeck 570316 1 Unit of Maxillofacial Surgery, Calabrodental, Crotone, Italy 2 Tecnologica Research Institute, Biomedical Section, Crotone, Italy *All authors equally contributed to this article. A supplemental appendix to this article is published electronically only at http://jdr.sagepub.com/supplemental. Corresponding Author: M. Tatullo, Scientific Director, Tecnologica Research Institute, St. E. Fermi, Crotone, Italy. Email: marco.tatullo@tecnologicasrl.com Human Periapical Cyst–Mesenchymal Stem Cells Differentiate Into Neuronal Cells M. Marrelli 1* , F. Paduano 2* , and M. Tatullo 2* Abstract It was recently reported that human periapical cysts (hPCys), a commonly occurring odontogenic cystic lesion of inflammatory origin, contain mesenchymal stem cells (MSCs) with the capacity for self-renewal and multilineage differentiation. In this study, periapical inflammatory cysts were compared with dental pulp to determine whether this tissue may be an alternative accessible tissue source of MSCs that retain the potential for neurogenic differentiation. Flow cytometry and immunofluorescence analysis indicated that hPCy- MSCs and dental pulp stem cells spontaneously expressed the neuron-specific protein β-III tubulin and the neural stem-/astrocyte-specific protein glial fibrillary acidic protein (GFAP) in their basal state before differentiation occurs. Furthermore, undifferentiated hPCy-MSCs showed a higher expression of transcripts for neuronal markers (β-III tubulin, NF-M, MAP2) and neural-related transcription factors (MSX-1, Foxa2, En-1) as compared with dental pulp stem cells. After exposure to neurogenic differentiation conditions (neural media containing epidermal growth factor [EGF], basic fibroblast growth factor [bFGF], and retinoic acid), the hPCy-MSCs showed enhanced expression of β-III tubulin and GFAP proteins, as well as increased expression of neurofilaments medium, neurofilaments heavy, and neuron-specific enolase at the transcript level. In addition, neurally differentiated hPCy-MSCs showed upregulated expression of the neural transcription factors Pitx3, Foxa2, Nurr1, and the dopamine-related genes tyrosine hydroxylase and dopamine transporter. The present study demonstrated for the first time that hPCy-MSCs have a predisposition toward the neural phenotype that is increased when exposed to neural differentiation cues, based on upregulation of a comprehensive set of proteins and genes that define neuronal cells. In conclusion, these results provide evidence that hPCy-MSCs might be another optimal source of neural/glial cells for cell-based therapies to treat neurologic diseases. Keywords: dental pulp, periapical tissue, radicular cyst, regenerative medicine, stem cell research, neurogenesis by guest on February 12, 2015 For personal use only. No other uses without permission. jdr.sagepub.com Downloaded from © International & American Associations for Dental Research 2015