Objective To analyze the effects of 2D culture and micropellet culture on the chondrocyte phenotype . Methods High density 2D culture and micropellet culture were used to culture rabbit chondrocytes ,the cell morphology and level of matrix expression were measured .Results After 2 weeks of 2D high density culture ,multilayer chondrocyte distribution was ob‐served .HE staining showed that the cells were round in shape ,and were closely connected with each other ,alcian blue staining showed that the secretion of proteoglycan was low ;after 2 weeks of micropellet culture ,cartilage‐like white tissue was formed .HE staining showed that the cells were polygonal in shape ,and were sparsely distributed ,alcian blue staining showed that the secretion of proteoglycan was significantly higher than that in 2D culture(P<0 .05) .Conclusion Using micropellet to culture rabbit chon‐drocytes is favorable for the secretion of extracellular matrix .

OBJECTIVE:To optimize the formulation and preparation technology of Propylthiouracil(PTU)solid lipid nanopar-ticles(PTU-SLN)and to evaluate the quality of PLN-SLN. METHODS:PTU-SLN was prepared by emulsion ultrasound dispersing method. The formulation of PTU-SLN was optimized by orthogonal design with the entrapment efficacy and particle size as index, using the amount of lipid material,soybean lecithin and poloxamer 188 and ultrasonic time as factors. The quality of prepared nanoparticles was evaluated with particle size,Zeta potential,entrapment efficiency,stability and in vitro drug release rate as in-dex. RESULTS:The optimal formulation and technology was as follows as lipid material 0.6 g,soybean lecithin 1.0 g,poloxamer 188 0.8 g,ultrasonic time 10 min. The obtained PTU-SLN was round and smooth in appearance and distributed evenly in particle size with average particle size of 93.5 nm,Zeta potential of -30.8 mV and average entrapment efficiency of 74.9%. Prepared nanoparticles had no significant change after placing for 15 d at 4 ℃. Accumulative release rate of PTU-SLN was 56.1% at 4 hour in vitro and reached 98.4% at 24 hour. CONCLUSIONS:PTU-SLN is prepared successfully and reasonable in technology,and can reach sustained-release effects.