Study on Osteogenic and Endothelial Differentiation Potential of Human Dermal Fibroblasts

repair and regeneration of bone defects, especially the criticalsized bone defects resulting from trauma, surgical resection and congenital deformity corrections [3].The construction of tissue engineering bone has been proved one of the most effective ways for repairing bone defects, especially the large bone defects [4].The seed cell is one of three key factors for bone tissue engineering.The ideal seed cells should be those that have the following characteristics such as abundant source, easy accessibility, less injury to body and strong proliferation ability in vitro culture.However, the insufficiency of seed cell source is a major obstacle to the clinical application of bone tissue engineering [5][6].Since the late 90s, stem cells, such as human embryonic stem cells, induced pluripotent stem cells and Mesenchymal Stem Cells (MSCs), have been considered as a potential source of seed cells for regenerative medicine and tissue engineering.Among these stem cells, MSCs show some advantages over the others, such as possible clinical application as autologous cells and low immunogenicity [7].However, the extremely low proportion of MSCs in human body leads to a complicated process and in turn a great deal of time and expense required to isolate and to expand them in vitro, thus restricting the clinical application of autologous MSCs.As such, the clinical limitation of autologous MSCs has made researchers to have to look for an alternative autologous cell source for future tissue engineering [8][9].Human Dermal Fibroblasts (hDFs) are the most widely distributed in the body and they are very simple to culture or to obtain when compared with MSCs.They are regarded as the greatest number of "seed cell banks" in the human body [10].Human Dermal Fibroblasts (hDFs), derived from the embryonic mesoderm stromal cells, have become one of the most important sort of cells in tissue repair.In recent years, there has been increased interest in dermal fibroblasts in the field of differentiation research, although, in the past, dermal fibroblasts were only regarded as fully differentiated cell terminal during the development of human body, did not have the potential of multi-directional differentiation, could only be seed cells of AbstractTissue engineering has been proved one of the most effective ways for repairing bone defects.However, the insufficiency of seed cell source is a major obstacle.Human Dermal Fibroblasts (hDFs) are the most widely distributed in the body and very simple to culture or to obtain when compared with mesenchymal stem cells, and have become one of the most important cell sources.However, there is no report on using hDFs as an autologous seed cell source.This study aimed to examine whether hDFs would possess the capacity to differentiate into osteogenic and endothelial cell lineages.Low Intensity Pulsed Ultrasound (LIPUS) was applied to stimulate osteogenic and endothelial differentiations of hDFs.The results showed that hDFs were successfully differentiated into both osteogenic and endothelial cell lineages, which have been confirmed by checking ALP activity and calcium nodules as well as expression levels of CD80, RUNX2, OCN, CD31, AGTR1 and KDR.The application of LIPUS and RGD modification indicated much higher expression levels of these markers.These results revealed that hDFs possess the capacity to differentiate into both osteogenic and endothelial cell lineages and might be an alternative autologous seed cell source for bone tissue engineering.