Biological Characteristics of Fluorescent Superparamagnetic Iron Oxide Labeled Human Dental Pulp Stem Cells

Biological Characteristics of Fluorescent Superparamagnetic Iron Oxide Labeled Human Dental Pulp Stem Cells Liang Ma,1,2 Ming-wei Li,1 Yu Bai,1 Hui-hui Guo,1 Sheng-chao Wang,3 and Qing Yu1 1State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases, Department of Operative Dentistry and Endodontics, The Fourth Military Medical University, Xi’an, China 2Department of Stomatology, No. 44 Hospital of Chinese PLA, Guiyang, Guizhou, China 3State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases, Department of Preventive Dentistry, School of Stomatology, The Fourth Military Medical University, Xi’an, China Correspondence should be addressed to Sheng-chao Wang; nc.ude.ummf@oahcgnehsgnaw and Qing Yu; nc.ude.ummf@gniquy Received 20 August 2016; Revised 8 October 2016; Accepted 23 November 2016; Published 16 February 2017 Academic Editor: Marc L. Turner Copyright © 2017 Liang Ma et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Tracking transplanted stem cells is necessary to clarify cellular properties and improve transplantation success. In this study, we investigate the effects of fluorescent superparamagnetic iron oxide particles (SPIO) (Molday ION Rhodamine-B™, MIRB) on biological properties of human dental pulp stem cells (hDPSCs) and monitor hDPSCs in vitro and in vivo using magnetic resonance imaging (MRI). Morphological analysis showed that intracellular MIRB particles were distributed in the cytoplasm surrounding the nuclei of hDPSCs. 12.5–100 μg/mL MIRB all resulted in 100% labeling efficiency. MTT showed that 12.5–50 μg/mL MIRB could promote cell proliferation and MIRB over 100 μg/mL exhibited toxic effect on hDPSCs. In vitro MRI showed that 1 × 106 cells labeled with various concentrations of MIRB (12.5–100 μg/mL) could be visualized. In vivo MRI showed that transplanted cells could be clearly visualized up to 60 days after transplantation. These results suggest that 12.5–50 μg/mL MIRB is a safe range for labeling hDPSCs. MIRB labeled hDPSCs cell can be visualized by MRI in vitro and in vivo. These data demonstrate that MIRB is a promising candidate for hDPSCs tracking in hDPSCs based dental pulp regeneration therapy. 1. Introduction Human dental pulp stem cells (hDPSCs), firstly isolated from adult human third molar dental pulp, have been described to be possess self-renewal capacity, high proliferation potential, and the ability to undergo multilineage differentiation [1]. Compared with other adult stem cells, hDPSCs exhibit a stronger proliferation potential and dentinogenic ability [2]. Recent study reported strong neurogenic potential as hDPSCs highly expressed III β-tubulin (TUBB3) and microtubule-associated protein 2 (MAP2) under inductive condition [3]. Furthermore, it has been shown that hDPSCs seem to be a particularly good choice for reconstruction of different craniomaxillofacial tissues and organs, such as cranial bones, nerves, teeth, and salivary glands [4]. Taken together, these studies provide sufficient evidence to regard hDPSCs as an important candidate for future cell-based clinical applications. For a successful stem cell therapy, an underlying prerequisite is survival and appropriate localization of the transplanted stem cells [5]. Therefore, cell tracking in vivo is important for the development of successful stem cell therapies. With superior resolution and localization, magnetic resonance imaging (MRI) has emerged as the leading modality for tracking transplanted stem cells in living animals and clinical studies [6]. The advantages of MRI are that it is noninvasive and is suitable for longitudinal studies [7]. To distinguish specific cells using MRI, transplanted cells must be labeled with a magnetic contrast agent. In recent years, various magnetic nanoparticles, such as superparamagnetic iron oxide (SPIO), have been widely applied both in cell tracking and in magnetic targeting [8–10]. However, before being applied for both experimental animals and eventually clinical use, the biological impacts of different kinds of SPIO on different types of stem cells must be investigated. Currently, MIRB (Molday ION Rhodamine B; BioPAL, Worcester, MA, USA), as a new USPIO agent, has become a new research hot spot in stem cell labeling and tracking [11–13]. Compared with other SPIOs, it has higher labeling efficiency and can be internalized by stem cells without the use of adjuvant transfection agents and can be visualized by both MRI and fluorescence microscopy [14]. A variety of cell types have been successfully labeled with MIRB and their proliferation, phenotype, and differentiation after labeling were investigated [5, 6, 12, 14, 15]. H (...truncated)