OBJECTIVESeed cell study is an essential area in the research of tissue engineering. To evaluate the potentiality of marrow stromal cell(MSCs) as seed cell in the regeneration of tissue engineered cartilage, formation of cartilage nodules by culture expanded MSCs pellets under the induction of TGF-beta was investigated.

METHODSMSCs were cultured and expanded in vitro. Cell pellets containing 1 x 10(6) MSCs were obtained by centrifuging MSCs solution at 1,000 r/min in 5 ml centrifugation tube. Pellets were exposed to cell culture media containing 20 ng/ml TGF-beta for 7 days and then cultured for another 7 and 21 days. The nodules were moved out of the tube and cartilage formation was observed by stereomicroscope, light microscope and electronic microscope.

RESULTS10 days after exposure to TGF-beta, pellets contracted and formed small and round nodules on the bottom of the tubes. The nodules grew bigger slowly and reached maximal diameter of 1.8 mm in 28 days. The surface of the nodules was smooth and bright white. Histological examination showed that extra cellular matrix formed in 14 days and in some areas cells situated in lacuna. In 28 days' specimens, a lot of cells situated in lacuna could be observed and the histological appearance looked much similar to cartilage. Electronic microscope observation demonstrated that in 28 days' specimens a large amount of collagen fiber existed.

CONCLUSIONUnder the induction of TGF-beta, MSCs could differentiate into chondrogenesis cell and form cartilaginous nodules in vitro. This indicated that MSCs could be the potential seed cells in the regeneration of cartilage employing method of tissue engineering.