Obej ctive Knockout mice are widely used in the studies of joint diseases .This article investigated the effects of joint processing methods , collagenase types ,and collagenase digestion time on the number of primary fibroblast -like synoviocytes (FLSs) obtained from mice. Methods The hind legs of 6 of the 12 male mice were cut open from the hip joints , but not those of the other 6.FLSs were isolated using the type-Ⅳcollagenase digestion method and purified by differential digestion .Cell morphology was observed under the inverted microscope .The type, viability, and purity of the cells were determined by flow cytometry . Rse ults Significantly fewer FLSs were obtained from the mice with the hind legs cut open ( 19 133 ±115 ) than from those without (24 933 ± 503) (P<0.05).The numbers of FLSs collected from the cell suspension at 1, 2, 3, 4, 5,6 , and 7 hours after digestion were 700 ±300 , 600 ±100 , 15 200 ±900 , 5100 ±800 ,2700 ±300 , 900 ±200, and 300 ±100, respectively, the highest at 3 hours. There were statistically significant differences in the total number of FLSs obtained by type-Ⅳ and type-Ⅱ collagenase digestions (24900 ±500v s 18 100 ±400, P<0.05). Conclusion For in virt o culture of primary mouse FLSs, it is recommended that the hip joints be not cut open, and type-Ⅳcollagenase be used with cell sus-pension at 2-6hours after digestion .

OBJECTIVE： To investigate the effects of benzoxazole derivative 2-（chlorobenzoxazolyl-2-yl）-4，5，6，7-tetrahydro- dihydro-indazole-3-ol （PO-296） on the differentiation of murine bone marrow-derived dendritic cells（DC） and their related indexes as specific surface molecules and inflammatory cytokines. METHODS： Bone marrow nuclear cells of mice were isolated， and immature DC （imDC） was obtained by recombinant mice granulocyte macrophage colony-stimulating factor and recombinant mice IL-4. After pretreated with low-dose， medium-dose and high-dose （1， 5， 25 μmol/L） of PO-296， DC was obtained by lipopolysaccharide induction. Flow cytometry was used to detect the expression of DC specific surface molecules [i.e. the proportion of class Ⅱ major histocompatibility complex （MHC Ⅱ）， CD80， CD86 and chemokine receptor 7 （CCR7） positive cells]， imDC phagocytosis （i.e. the proportion of dextran positive cells） and DC survival （i.e. the proportion of survival cells）. ELISA method was used to detect the levels of inflammatory cytokines （IL-10， IL-12 and TNF-α） in cell culture medium. RESULTS： Compared with imDC group， the proportion of MHC Ⅱ， CD80 and CD86 positive cells were increased significantly in non-loading group （P＜0.05）. Compared with non-loading group， the levels of IL-10 in cell culture medium were increased significantly in PO-296 groups. The proportions of MHC Ⅱ， CD80 and CD86 positive cells in positive group and PO-296 medium-dose and high-dose groups as well as the levels of IL-12 and TNF-α in cell culture medium in administration groups were decreased significantly （P＜0.05）. There was no statistical significance in the proportion of CCR7 positive cells， dextran positive cells and survival cells in administration groups， compared with non-loading group （P＞0.05）. CONCLUSIONS： PO-296 has no obvious cytotoxicity and does not affect the phagocytic function of imDC. At the same time， the compound can inhibit the expression of DC specific surface molecules and regulate the secretion of inflammatory cytokines.