Forced expression of Lmx1b enhances differentiation of mouse ES cells into serotonergic neurons

The LIM homeodomain transcription factor Lmx1b is a key factor in the specification of the serotonergic neurotransmitter phenotype. Here, we explored the capacity of Lmx1b to direct differentiation of mouse embryonic stem (mES) cells into serotonergic neurons. mES cells stably expressing human Lmx1b were generated by lentiviral vector infection. Clones expressing Lmx1b at a low level showed increased neurogenesis and elevated production of neurons expressing serotonin, serotonin transporter, Tryptophan hydroxylase 2, and transcription factor Pet1, the landmarks of serotonergic differentiation. To explore the role of Lmx1b in the specification of the serotonin neurotransmission phenotype further, a conditional system making use of a floxed inducible vector targeted into the ROSA26 locus and a hormone-dependent Cre recombinase was engineered. This novel strategy was tested with the reporter gene encoding human placental alkaline phosphatase, and demonstrated its capacity to drive transgene expression in nestin+ neural progenitors and in Tuj1+ neurons. When it was applied to the inducible expression of human Lmx1b, it resulted in elevated expression of serotonergic markers. Treatment of neural precursors with the floor plate signal Sonic hedgehog further enhanced differentiation of Lmx1b-overexpressing neural progenitors into neurons expressing 5-HT, serotonin transporter, Tryptophan hydroxylase 2 and Pet1, when compared to Lmx1b-non expressing progenitors. Together, our results demonstrate the capacity of Lmx1b to specify a serotonin neurotransmitter phenotype when overexpressed in mESC-derived neural progenitors

Treatment of proximal deep vein thrombosis with a novel synthetic compound (SR90107A/ORG31540) with pure anti-factor Xa activity - A phase II evaluation

Background-Patients with venous thromboembolism require initial treatment with an immediate-acting anticoagulant, low-molecular-weight heparin. We evaluated a novel synthetic factor Xa inhibitor (SR90107a/ORG31540) as an alternative treatment. Methods and Results-A randomized-parallel-group, phase II trial to assess the efficacy and safety of SR90107a/ORG31540 (5, 7.5, or 10 mg once daily) relative to low-molecular-weight heparin (dalteparin, 100 IU/kg twice daily) in symptomatic proximal deep vein thrombosis. The primary outcome measure was the change in thrombus mass, assessed by ultrasonography of the leg veins and perfusion lung scintigraphy, performed at baseline and day 7+/-1. A positive outcome was defined as improvement of the ultrasound and/or perfusion scan result without deterioration of either test. Other outcome measures included symptomatic, recurrent venous thromboembolism and major bleeding for a period of 3 months. All outcomes were interpreted with the observer unaware of treatment allocation. A positive primary outcome was observed in 46 of 100 (46%), 52 of 108 (48%), 48 of 115 (42%), and 56 of 115 (49%), respectively, of the subjects given 5, 7.5, or 10 mg SR90107a/ORG31540 or dalteparin. There were 8 recurrent thromboembolic complications (2.4%) in the 334 patients treated with SR90107a/ORG31540 and 6 (5.0%) in the 119 dalteparin patients, a difference of 2.6% in favor of SR90107a/ORG31540 (95% CI -2.1% to 10.1%). The incidence of bleeding was low and was similar among the groups. Conclusions-The factor Xa inhibitor SR90107a/ORG31540 appears to be an effective and safe treatment for patients with deep vein thrombosis across a wide range of doses. This synthetic compound merits evaluation in phase III studies