Morphological features of osteoblasts cultured on ultraviolet-irradiated titanium plates.

BACKGROUND: Although we have recently established optimal experimental conditions of ultraviolet (UV)-irradiation for titanium plates (e.g. wavelength and exposure time) which enhanced osteoblast adhesion to the plates, the effects of UV-irradiation on cell structure are still unclear. MATERIALS AND METHODS: Digital stereomicroscopy was used to investigate morphological alterations of non-stained viable and hematoxylin-eosin (HE)-stained cells on UV-irradiated and non-UV-irradiated titanium plates for up to 24 hours. RESULTS: In 24 hours, significant expansion of HE-stained cells (area, perimeter and sprouting processes) was observed on UV-irradiated plates. The sprouting processes appeared within 40 minutes of inoculation under both conditions, however, significant cell area expansion, which occurred in 5 minutes, was observed only on UV-irradiated plates. CONCLUSION: UV-enhanced cell attachment was related to morphological alteration which occurred immediately after inoculation. Digital stereomicroscopic evaluation was able to define and quantify morphological alterations of viable cells in an opaque environment.

Modulation of branching morphogenesis of fetal mouse submandibular gland by sodium ascorbate and epigallocatechin gallate.

As an initial step to study the effect of antioxidants on the oral environment, we here investigated how sodium ascorbate and (-)-epigallocatechin 3-O-gallate (EGCG) affect the branching morphogenesis of the fetal mouse submandibular gland (SMG). When mouse SMG was prepared from the embryo at 13-day post prenatal stage and cultured, gradual development of branching morphogenesis was observed. Addition of sodium ascorbate affected this morphological change in a bimodal fashion. At lower concentrations of sodium ascorbate (0.25 approximately 2.27 mM), the branching morphogenesis was slightly but significantly (about 60%) enhanced, whereas at higher concentrations of sodium ascorbate (6.82 approximately 10.1 mM), the branching morphogenesis was inhibited. The addition of EGCG failed to stimulate, but inhibited the branching morphogenesis in a dose-dependent manner. These data support that the addition of a lower concentration of sodium ascorbate is essential to stimulate the growth of SMG, and that sodium ascorbate, but not all antioxidants, induces hormesis (beneficial action at lower concentration) in the present SMG system.

Inhibition of branching morphogenesis of mouse fetal submandibular gland by sodium fluoride--protection by epidermal growth factor.

As an initial step to study the effect of sodium fluoride on the oral environment, we investigated how sodium fluoride (NaF) affects the branching morphogenesis of fetal mouse submandibular gland (SMG). When mouse SMG was prepared from the embryo at 13 days post prenatal stage and cultured, gradual development of branching morphogenesis was observed. Addition of NaF affected this morphological change in bimodal fashions. At a lower concentration of NaF (< 2 microM), the branching morphogenesis was slightly enhanced, whereas at a higher concentration of NaF (4 - 8 microM), it was almost completely inhibited. The inhibitory effect of NaF at the higher concentration was abrogated by stimultaneous addition of epidermal growth factor (EGF), but not by 5alpha-dihydrotestosterone (DHT) or insulin-like growth factor (IGF). These data demonstrate that EGF can effectively reduce the cytotoxic activity of NaF at micromolar concentration.