Effect Of The Strain To The Function Of Osteoblast And It's Three-dimensional Culture

It is well recognized that mechanical strain plays a crucial role in bone remodeling,affecting activities and differentiation of osteoblast, however,little is known on how mechanical strain is transduced into cellular responses and controls the differentiation and maintains the phenotypes of osteoblastosteoblasts can be stimulated under exposed to mechanical strain with four-point-bend loading device with uniaxial strain,in our study,therefore,we loaded osteoblasts with different strain and stimulation times at physiological magnitude by this device,examine the time course of cell changes following exposed to mechanical loading.the result show that both the two different mechanical strain promoted the proliferation of the osteoblast;at the same time,as the loading going,the alkaline phosphatase(ALP) activity increase first,decrease later,restore to normal level at last;the expression of collagen I was increased first and then decreased.these results demonstrate that loaded the osteoblast at 1000 and 2000 u strain promoted the differentiation of osteoblast in the period of 6 to 12h,elevated the bone formation,and converse result was observed in the period of 12 to 24h.we also find transiently changed of Immediate early genes(such as c-fos).all these results indicated that mechanical strain affected the fuction and activity of osteoblast at molecular and cellular levels.It has been well shown by many studies that mechanical strain affected the activities and differentiation of osteoblast,regulate the production and remodeling of bone,however,cellular reactions which adapt bone tissue to the mechanical envioment are not definitively determinedproteomics is a newly emerging field in the post-genomics era.The development of knowledge and technologies in proteomics has provided a new way to understand the molecular mechanisms of the function adapted of osteoblast under mechanical loading.in our study,high resolution two-dimensional polyacrylamide gel electrophoresis(2-DE), Followed by computer-assisted image analysis was used to screen protein patterns of normal and strain-induced osteoblast for quantitative differences in protein expression. 512 + 11 proteinspots were resolved in unload osteoblast and 533 + 14 protein spots were resolved in load osteoblastthe results also showed that 9 protein spots displayed quantitative changes in expression after induction of mechanical strain,of which,2 decreased in abundance and 7 showed higher expression.thses proteins may be involved in the cellular response to mechanical strain of osteoblast,furthermore,it is helpful to the research of singal-transduction. Our research also explore the possibility of construction of the tissue engineered bone through the three-dimensional culture of osteoblastosteoblast were isolated and cultured from the parietal bone chips of Wistar mice,at the third passage ,cells were cxiltured on CHA scaffold,and then were cultured in rotary cell culture system (RCCS).The osteogenic potential of the cell-CHA scaffold constructs cultured in RCCS were investigated by Alizarin Red S(ARS) staining, MTT method and histochemistry at 14th .Through our study ,we find that osteoblast showed good biocompatibility with CHA matrix scaffold,the scaffold promoted the proliferation of osteoblast remarkably in RC.CS,staining wih ARS revealed weakly positive reaction on the 14th,at the same time,the secretion of ALP was decreased.these results showed that CHA material and RCCS provided suitable microenvironment for osteoblasts.the osteoblasts coculture with CHA in RCCS might be an ideal method for construction of tissue engineered bone in vitro.