IGF I and IGF II Induce Osteo/Odontoblastic Differentation In Vitro

Objectives: The insulin-like growth-factor (IGF) system plays an important role in the process of bone acquisition, and exfoliated deciduous teeth are great sources of stem cells(SCs) that are responsible for tooth formation. The aim of this study is to determine whether IGFI and IGFII inhibits or promotes the osteo/odontogenic differentiation in vitro.
Methods: In this study, SCs were obtained from deciduous teeth of 10 healthy subjects that are extracted for orthodontic reasons in the pediatric dental clinic of Istanbul University, Faculty of Dentistry, Istanbul. Mesenchymal SCs were isolated from the pulp-tissue and cultured, then stimulated by 50ng/mL and 100ng/mL exogenous IGFI and IGFII separately. For passage3, immunophenotypic assays were performed with flow cytometry and immunohistochemical methods. All experiments were carried out in triplicate, and means and standard deviations were determined. All statistical analysis were performed using SPSS 10.0 (SPSS Inc., Chicago, IL, USA). Data were analyzed using one-way ANOVA and paired t-test.
Results: It has been demonstrated that SCs from human exfoliated deciduous teeth (SHEDs) expressed mesenchymal cell markers such as CD13, CD105, CD73, CD44 and CD90 in high levels. Differentiation assays with various stimulants in the culture points out that SHEDs have adipogenic, neurogenic and osteogenic differentiation capacity. At the end of the 14th day, all the IGFI and IGFII stimulated groups, especially 100ng/mL IGF-I-induced group, showed significantly high levels of osteogenic differentiation compared to the control group.
Conclusions: The in vitro evidence accumulated in this study revealed that various doses of IGFI and IGFII can promote the osteogenic differentiation and osteogenesis, suggesting that IGFI and IGFII treated SHEDs can be used as a potential candidate for bone tissue-engineering. Further studies are required to explore the potential signaling pathways regulating the osteogenic differentiation of IGFI and IGFII treated SHEDs.