The effect of biomechanical stimulation on osteoblast differentiation of human jaw periosteum-derived stem cells / 대한악안면성형재건외과학회지

BACKGROUND: This study was to investigate the effect of biomechanical stimulation on osteoblast differentiation of human periosteal-derived stem cell using the newly developed bioreactor. METHODS: Human periosteal-derived stem cells were harvested from the mandible during the extraction of an impacted third molar. Using the new bioreactor, 4% cyclic equibiaxial tension force (0.5 Hz) was applied for 2 and 8 h on the stem cells and cultured for 3, 7, and 14 days on the osteogenic medium. Biochemical changes of the osteoblasts after the biomechanical stimulation were investigated. No treatment group was referred to as control group. RESULTS: Alkaline phosphatase (ALP) activity and ALP messenger RNA (mRNA) expression level were higher in the strain group than those in the control group. The osteocalcin and osteonectin mRNA expressions were higher in the strain group compared to those in the control group on days 7 and 14. The vascular endothelial growth factor (VEGF) mRNA expression was higher in the strain group in comparison to that in the control group. Concentration of alizarin red S corresponding to calcium content was higher in the strain group than in the control group. CONCLUSIONS: The study suggests that cyclic tension force could influence the osteoblast differentiation of periosteal-derived stem cells under optimal stimulation condition and the force could be applicable for tissue engineering.

Delayed Cerebral Infarction after Resection of Craniopharyngioma

Delayed cerebral infarction after resection of craniopharyngioma is a uncommon entity, but leads to high morbidity and mortality. We present 3 such cases and discuss the etiology and pathogenesis with review of pertinent literatures. In our cases, delayed deterioration of consciousness was observed in all cases. All of them expired. The cause may be multifactorial and the surgical approach may contribute to the pathogenesis of delayed cerebral infarction. We suspect vasospasm might be the major mechanism of pathogenesis. Vessels were primed to spasm during operation due to blood in the cistern or mechanical injury. Vasoactive materials may have been liberated from the pituitary stalk or injured hypothalamus, either at the time of surgery, or later, after portions of tumor have undergone necrosis. The high degree of suspicion to detect vasospasm should be done in the case of the delayed deterioration of mental status at an early stage of craniopharyngioma surgery. Possible mechanism underlying this delayed cerebral infarction are discussed.