Insulin-like growth factor 1 (IGF1) affects proliferation and differentiation and wound healing processes in an inflammatory environment with p38 controlling early osteoblast differentiation in periodontal ligament cells

Abstract

ObjectiveThe objective of this study was to investigate effects of insulin-like growth factor 1 (IGF1) on proliferation, wound healing and differentiation processes of human periodontal ligament (PDL) cells under inflammatory conditions and whether the protective, anabolic effects of IGF1 can attenuate unfavorable effects of interleukin-1β (IL-1β). DesignInflammation was mimicked through cell stimulation with IL-1β. PDL cells were characterized in respect to the presence of components of the IGF system and the responsive potential on IL-1β incubation. Gene expression levels were analyzed by quantitative real-time PCR. Cellular localization of target proteins was visualized using fluorescent-based immunohistochemistry. Effects on cell division were investigated by proliferation assays. Wound healing was analyzed using light microscopic techniques. Differentiation was quantified by measuring biomineralization and osteoblast-specific alkaline phosphatase enzyme activity. ResultsPDL cell proliferation and wound healing were positively affected by IGF1 and the combination of IGF1 with IL-1β, while only IL-1β showed negative effects. Biomineralization was enhanced by IGF1, IL-1β, and the combination of both stimulants. Osteoblast differentiation was increased by IL-1β and the combination of IL-1β with IGF1, whereas only IGF1 negatively affected ALP activity. Phosphorylation of p38 was regulated by IL-1β and IGF1. ConclusionsThe data presented in this work showed a potential of IGF1 to improve wound healing and proliferation processes and to sustain cell differentiation under inflammatory stimuli in PDL cells.