Integrin-ß1, not integrin-ß5, mediates osteoblastic differentiation and ECM formation promoted by mechanical tensile strain

BACKGROUND: Mechanical strain plays a great role in growth and differentiation of osteoblast. A previous study indicated that integrin-ß (ß1, ß5) mediated osteoblast proliferation promoted by mechanical tensile strain. However, the involvement of integrin-ß; in osteoblastic differentiation and extracellular matrix (ECM) formation induced by mechanical tensile strain, remains unclear. RESULTS: After transfection with integrin-ß1 siRNA or integrin-ß5 siRNA, mouse MC3T3-E1 preosteoblasts were cultured in cell culture dishes and stimulated with mechanical tensile strain of 2500 microstrain (µÎµ) at 0.5 Hz applied once a day for 1 h over 3 or 5 consecutive days. The cyclic tensile strain promoted osteoblastic differentiation of MC3T3-E1 cells. Transfection with integrin-ß1 siRNA attenuated the osteoblastic diffenentiation induced by the tensile strain. By contrast, transfection with integrin-ß5 siRNA had little effect on the osteoblastic differentiation induced by thestrain. At thesametime, theresultofECM formation promoted by the strain, was similar to the osteoblastic differentiation. CONCLUSION: Integrin-ß1 mediates osteoblast differentiation and osteoblastic ECM formation promoted by cyclic tensile strain, and integrin-ß5 is not involved in the osteoblasts response to the tensile strain.

Neurogenesis of Adipose-derived Stem Cells in Hydrogel / 华中科技大学学报（医学）（英德文版）

Adipose tissue is a readily available source of adult stem cells with multipotent properties suitable for tissue engineering and regenerative medical applications.Peptide hydrogel is a novel biomaterial which provides three-dimensional microenvironments for a variety of cells for tissue grafting.In this study,adipose-derived stem cells (ADSCs) were isolated from rats,seeded into the peptide hydrogel polymer scaffolds and cultured in Neurobasal (NB) media supplemented with B27,basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF).Ten days after the culture,some cells were expanded into clonal populations in which the expression of both Nestin and Brdu was detected but only Brdu expression was detected in the cells that were not expanded into clonal populations.Our results suggested that ADSCs in peptide hydrogel polymer scaffolds can be induced to differentiate into cells capable of expressing the neuron-associated markers,self-renewal and self-propagation.