Platelet-Rich Fibrin-Conditioned Medium as an Alternative to Fetal Bovine Serum Promotes Osteogenesis of Human Dental Pulp Stem Cells.

Human dental pulp stem cells (DPSCs) exhibit multilineage differentiation capabilities and superior clonogenic and proliferative properties. However, the use of animal-derived components such as FBS raises concerns regarding the clinical application of stem-cell-based therapies. Platelet-rich fibrin (PRF) derived from human blood is rich in fibrin, platelets, and growth factors and acts as a bioactive scaffold for grafting with biomaterials. In this study, we assessed the efficacy of PRF-conditioned medium (CM) in promoting DPSCs proliferation and osteogenic differentiation compared with the standard culture medium supplemented with FBS. A comparison of DPSCs cultured in FBS and PRF-CM revealed no differences in characteristics or morphology. However, cells cultured with PRF-CM exhibited inferior proliferation rates and cell numbers during passage in comparison with those cultured with FBS. In contrast, DPSCs cultured in PRF-CM showed significantly higher levels of calcification, and RT-PCR confirmed that the gene expression levels of markers associated with osteoblast differentiation were significantly increased. The PRF-CM approach offers a convenient, straightforward, and advantageous method for culturing DPSCs, without relying on animal-derived components. In summary, this study introduces a novel application of PRF-CM for enhancing the osteogenesis of DPSCs, which provides an alternative to FBS culture medium and addresses concerns associated with the use of animal-derived components in clinical settings.

VCAM-1 and GFPT-2: Predictive markers of osteoblast differentiation in human dental pulp stem cells.

INTRODUCTION: Dental pulp stem cells (DPSCs) have high proliferative and multilineage differentiation potential in mesenchymal stem cells. However, several studies have indicated that there are individual differences in the potential for osteogenic differentiation of DPSCs, and the factors determining these differences are unknown. OBJECTIVE: To identify the genes responsible for the individual differences in the osteogenic differentiation ability of DPSCs. METHODS: We divided DPSCs into high and low osteogenic differentiation ability groups (HG or LG) with ALP and von Kossa stain, and compared the gene expression patterns using RNA-seq. In addition, genes that may affect osteogenic differentiation were knocked down using small interfering RNA (siRNA) and their effects were investigated. RESULTS: The RNA-seq patterns revealed that VCAM1 and GFPT2 were significantly expressed at higher levels in the HG than in the LG. The results of siRNA analysis showed that VCAM1 and GFPT2 knockdown significantly reduced the expression of osteogenic markers. Furthermore, we analyzed the involvement of these two genes in cell signaling in DPSC differentiation. The results indicated that the VCAM1-mediated Ras-MEK-Erk and PI3K/Akt pathways are involved in the osteogenic differentiation of DPSCs, and that GFPT2-mediated HBP signaling influences the osteogenic differentiation of DPSCs. CONCLUSIONS: These findings indicate that DPSCs that highly express VCAM1 and GFPT2 have a high capacity for osteogenic differentiation. Evaluation of VCAM1 and GFPT2 expression in undifferentiated DPSCs may predict the outcome of bone regenerative therapy using DPSCs. Moreover, the expression levels of VCAM1 and GFPT2 in DPSCs may be useful in setting criteria for selecting donors for allogeneic cell transplantation for bone regeneration.

Effects of Helioxanthin Derivative-Treated Human Dental Pulp Stem Cells on Fracture Healing.

Bone defects affect patients functionally and psychologically and can decrease quality of life. To resolve these problems, a simple and efficient method of bone regeneration is required. Human dental pulp stem cells (DPSCs) have high proliferative ability and multilineage differentiation potential. In our previous study, we reported a highly efficient method to induce osteogenic differentiation using DPSC sheets treated with a helioxanthin derivative (4-(4-methoxyphenyl)pyrido[40,30:4,5]thieno[2,3-b]pyridine-2-carboxamide (TH)) in a mouse calvarial defect model. However, the localization of the DPSCs after transplantation remains unknown. Therefore, in this study, we investigated the localization of transplanted DPSCs in a mouse fracture model. DPSCs were collected from six healthy patients aged 18-29 years, cultured in normal medium (NM), osteogenic medium (OM), or OM with TH, and fabricated them into cell sheets. To evaluate the efficacy of fracture healing using DPSCs treated with OM+TH, and to clarify the localization of the transplanted DPSC sheets in vivo, we transplanted OM+TH-treated DPSC sheets labeled with PKH26 into mouse tibiae fractures. We demonstrated that transplanted OM+TH-treated DPSCs sheets were localized to the fracture site and facilitated bone formation. These results indicated that transplanted OM+TH-treated DPSCs were localized at fracture sites and directly promoted fracture healing.

Bone Regeneration Potential of Human Dental Pulp Stem Cells Derived from Elderly Patients and Osteo-Induced by a Helioxanthin Derivative.

Human dental pulp stem cells (DPSCs) have high clonogenic and proliferative potential. We previously reported that a helioxanthin derivative (4-(4-methoxyphenyl)pyrido[40,30:4,5]thieno[2-b]pyridine-2-carboxamide (TH)) enhances osteogenic differentiation of DPSCs derived from young patients. However, in the clinical field, elderly patients more frequently require bone regenerative therapy than young patients. In this study, we examined and compared the osteogenic differentiation potential of TH-induced DPSCs from elderly patients and young patients to explore the potential clinical use of DPSCs for elderly patients. DPSCs were obtained from young and elderly patients and cultured in osteogenic medium with or without TH. We assessed the characteristics and osteogenic differentiation by means of specific staining and gene expression analyses. Moreover, DPSC sheets were transplanted into mouse calvarial defects to investigate osteogenesis of TH-induced DPSCs by performing micro-computed tomography (micro-CT). We demonstrated that osteogenic conditions with TH enhance the osteogenic differentiation marker of DPSCs from elderly patients as well as young patients in vitro. In vivo examination showed increased osteogenesis of DPSCs treated with TH from both elderly patients and young patients. Our results suggest that the osteogenic differentiation potential of DPSCs from elderly patients is as high as that of DPSCs from young patients. Moreover, TH-induced DPSCs showed increased osteogenic differentiation potential, and are thus a potentially useful cell source for bone regenerative therapy for elderly patients.

Identification of neurospheres generated from human dental pulp stem cells in xeno-/serum-free conditions.

INTRODUCTION: Cell-based therapies require an emerging alternative treatment using easily harvested cell sources. Neural stem cells derived from various tissues, including brain, bone marrow, skin and retina can give rise to both neurons and glial cells. Recently, human dental pulp stem cells (DPSCs) and stem cells from human exfoliated deciduous teeth (SHED) were demonstrated to have mesenchymal stem cell-like abilities such as self-renewal and multi-lineage differentiation, including neuron and glial cells. Moreover, DPSCs and SHED show a higher proliferation rate and a higher number of population doublings compared with adult bone marrow stromal stem cells. Therefore, DPSCs are a useful source that can be applied in cell replacement therapy for various neurological disorders. Generally, the conventional culture methods for DPSCs have used serum, therefore the undefined components in culture medium may complicate investigations of the molecular mechanisms that control the self-renewal and differentiation of DPSCs. However, neural stem cells proliferate to form 'neurospheres' in suspension in vitro in the presence of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). No study to date has obtained neurospheres from DPSCs in serum-free conditions in primary culture. Thus, the aim of this study was to establish a method for the proliferation and neural differentiation of DPSCs in xeno- and serum-free conditions in primary culture. METHODS: DPSCs were obtained from the dental pulp of wisdom teeth from healthy individuals (18-41 years old) and cultured in conventional medium containing 15% fetal bovine serum and xeno-/serum-free medium. We evaluated the proliferation of DPSCs, neurosphere generation, and neural differentiation under xeno-/serum-free conditions by flow cytometry, immunohistochemistry, and real-time polymerase chain reaction. RESULTS: In proliferation medium without xeno/serum, DPSCs can proliferate and generate neurospheres, however, the neurospheres had limited self-renewal ability. Under differentiation conditions, class III ß-tubulin (TUBB3) and microtubule-associated protein (MAP2) were more significantly expressed in neurospheres derived from DPSCs in xeno-/serum-free culture conditions than in DPSCs in conventional culture conditions. CONCLUSIONS: Our result demonstrated that neurosphere generation from DPSCs in xeno-/serum-free culture may be an accessible source for clinical cell replacement therapies for neuronal degenerative diseases.