BACKGROUND:The biological substances fixed onto the implant surface, including specific proteins, enzymes, polypeptides, could promote the proliferation and differentiation of osteogenic cells in order to achieve a good osteogenic effect.
OBJECTIVE:To introduce the biological characteristics of the arginine-glycine-aspartic acid (RGD) peptides, cellbiological behavior and implant osseointegration in osteoporosis.
METHODS:Authors retrieved the relevant articles in PubMed database (January 1984 to January 2013), Wanfang database (January 2002 to December 2012) and CHKD database (January 2002 to December 2012) using the key words“RGD peptides, osteoporosis, bone marrow mesenchymal stem cells, osseointegration, osteoblast, induced differentiation”. Papers were included concerning the biological characteristics of RGD peptides, the biological behavior of cells and the bone-implant integration in osteoporosis.
RESULTS AND CONCLUSION:Osseointegration on the surface between implant and bone tissue can be further improved by grafting biological y active substance. Bionics modification, to simulate the extracellular matrix environment in vivo, can promote celladhesion and growth, which is an effective way to improve osseointegration and is also an important direction of research in the field of tissue engineering recently. The future research is focused on designing specific and efficient polypeptides and simple and effective fixation methods.

Objective To study the effects of different implantation angles of bi-leaflet mechanical heart valve(BMHV)on swirling flow in the aorta.Methods Based on the aortic CT images of a healthy volunteer,the effects of 4 different valve implantation angles(0°,45°,90° and 135°)on the aortic swirling flow under constant flow conditions were studied by computational simulation.Results The implantation of BMHV could seriously interfere with the aortic swirling flow,affecting the structure and helicity distributions of the swirling flow in ascending aorta,thus resulting in disturbed blood flows distal to the valve.The 135° implantation angle caused the most disruption to the swirling flow,leading to the largest areas of reversed swirling flows,while the 0° and 45° implantation angles caused relatively smaller damage to the swirling flow.The areas with low wall shear stress(<0.5 Pa)were the smallest when the implantation angle of BMHV was 0°.Conclusions At the implantation angle of 0°-45°,the disruption of BMHV to the swirling flow in ascending aorta was relatively small.Therefore,for different patients,the selection of implantation angle should be individualized according to the spatial geometry of their aorta(including the aortic sinuses),and the implantation angle can be determined between 0°-45°.