OBJECTIVETo study the possibility and mechanism by which the human umbilical blood mesenchymal stem cells (MSCs) are induced to differentiate into neuron in vitro by baicalin, a kind of flavonoid isolated from an important medicinal plant Scutellariae Radix.

METHODSHuman cord blood was obtained via sterile procedure with 20 U/ml of preservative-free heparin. MSCs were isolated by the two-step assay of gelatin sedimentation plus Ficoll centrifugation separation, purified and amplified in the liquid culture medium. According to the kind of antioxidants, the experiment was conducted in five groups: induction group, control group I, control group II, control group III and control group IV. Five subgroups of MSCs amplificated ex vivo for 2 weeks in each group were induced by the media containing baicalin (BC, 200 - 400 micromol/L) or baicalin-free for seven days. The media consisted of induction medium (DMEM plus 200 - 400 micromol/L of baicalin) and post-induction medium (DMEM plus 200 - 400 micromol/L of baicalin, B27). The expression of neuronal or glia specific markers was evaluated by using indirect immunofluorescence cytochemistry staining. The percentage of differentiated cells and living cells was measured by Hoechest 33,258 staining assay.

RESULTSAfter induction for 7 days, MSCs displayed neuronal morphologies, such as pyramidal cell bodies and processes formed extensive network. The undifferentiated cells did not exhibit a neuronal or glial phenotype, while the differentiating cells expressed NSE and MAP-2, the specific markers of neuron, but did not express GFAP, the specific marker of glia on the seventh day after induced by baicalin. The percentage of NSE and MAP-2 expressed on the seventh day after induced by baicalin was (76.3 +/- 9.2)% and (78.5 +/- 5.5)%, respectively, which was significantly higher compared with control group I, control group II and control group III (P < 0.01), respectively. In addition, the ratio of living cells after induced for seven days in the BC group was (85.3 +/- 4.8)%, which increased significantly compared with control group I, control group II and control group III (P < 0.01), respectively.

CONCLUSIONSBaicalin may induce the umbilical blood MSCs to neuron or neuron-alike cells in vitro in a moderate and stable manner. The mechanism of such an induction may be related with its controlling the activity of NF-kappaB which regulates the production of many kinds of cytokines, such as brain-derived neurotrophic factor (BDNF), etc.