Abstract: Objective To study the effects of pulsed ultrasound (PUS) and pulsed electromagnetic fields (PEMF) on the secretion of extracellular matrix from a culture complex during in vitro chondrogenesis.Methods All the rat bone marrow mesenchymal stem cell pellets were cultured in achondrogenic medium. Different intensities of PUS (100, 150, and 200 mW·cm^-2) and PEMF (1, 2, and 5 mT) were applied to the cell pellets for 2 weeks. Group N was cultured without PUS and PEMF stimulation as control. The culture medium was collected after 2 weeks of culture. Enzyme-linked immunosorbent assay (ELISA) was used to detect the type of collagen and glycosaminoglycan (GAG) in the culture medium. Results PUS increased the secreting-type collagen and GAG from cell pellets compared with group N (P<0.05), whereas there was no difference in different intensities (P>0.05). PEMF had no significant effect on the secretion of the type of collagen (P>0.05). A PEMF of 1 mT had no significant effect on the secretion of GAG (P>0.05). A PEMF 2 and 5 mT decreased the secretion of GAG (P<0.05). Conclusion To prevent the secretary of extracellular matrix may play a role in chondrogenic effect of PEMF.

Key words: pulsed ultrasound, pulsed electromagnetic field, chondrogenesis, extracellular matrix