IDG-SW3 represent a non-homogenous population progressing from early osteoblasts to late osteocytic. These cells express functional SV40 large T antigen that is induced in the presence of IFN γ under permissive temperature （33°C） and express GFP under control of the dentin matrix （Dmp1） promoter. Initial culture shows osteoblastic phenotype, however when under mineralizing conditions, the cells start to express early osteocyte markers such as E11/podoplanin, followed by Dmp1 and mature markers SOST and FGF23 by 21-28 days of culture. Similar to osteocytes in vivo, these cells respond to hormonal signals such as PTH and 1,25-dihydroxyvitamin-D3. IDG-SW3 cells can be maintained in both 2D and 3D cultures and are useful for study of osteocytes at various differentiation stages. It should be noted that these cultures may contain a mixture of osteoblasts and osteocytes at different stages of differentiation and for studies requiring enriched osteocytes, the Dmp1-GFP cells should be isolated by flow cytometry （FACS）.
