To protect the activity of transform growth factor-1(TGF-1)

the sulfated chitosan/polylysine/TGF-1(SCS/PLL/TGF-1) nanoparticles were prepared by a co-precipitation method.Along with the increase of sulfated chitosan concentration

the nanoparticles with larger size and more negatively-charged surface were obtained.Both the SCS/PLL and SCS/PLL/TGF-1 nanoparticles had a round morphology observed by transmission electron microscopy(TEM)

with a dry size of(17726) nm and(19535) nm

respectively.In vitro cell culture was performed to evaluate the differentiation of bone mesenchyrnal stem cells(BMSCs) induced by the SCS/PLL/TGF-1 nanoparticles.The result of cell proliferation showed that the addition of TGF-1 either in a free state or as nanoparticles could block the proliferation of BMSCs to some extent.However

compared to the blank

SCS/PLL and free TGF-1 groups

the SCS/PLL/TGF-1 group secreted the highest amount of glycosaminoglycans(GAGs).Moreover

the results of quantitative reverse transcription-polymerase chain reaction(qRT-PCR) also showed that the BMSCs seeded with the SCS/PLL/TGF-1 nanoparticles expressed significantly higher amount of collagen type II gene at day 14.All these results confirm that the bioactivity of TGF-1 can be largely preserved in the form of SCS/PLL/TGF-1 nanoparticles

leading to the preferential differentiation of BMSCs toward chondrocytes.