Using human pluripotent stem cells to untangle neurodegenerative disease mechanisms.

Human pluripotent stem cells, including embryonic (hES) and induced pluripotent stem cells (hiPS), retain the ability to self-renew indefinitely, while maintaining the capacity to differentiate into all cell types of the nervous system. While human pluripotent cell-based therapies are unlikely to arise soon, these cells can currently be used as an inexhaustible source of committed neurons to perform high-throughput screening and safety testing of new candidate drugs. Here, we describe critically the available methods and molecular factors that are used to direct the differentiation of hES or hiPS into specific neurons. In addition, we discuss how the availability of patient-specific hiPS offers a unique opportunity to model inheritable neurodegenerative diseases and untangle their pathological mechanisms, or to validate drugs that would prevent the onset or the progression of these neurological disorders.

Therapeutic Applications of Prostaglandins and Thromboxane A2 Inhibitors in Abdominal Aortic Aneurysms.

BACKGROUND: Abdominal aortic aneurysm (AAA) is one of the leading causes of death in western countries. Surgery is still, at the present time, the sole treatment that has however a significant mortality and cost rate. Many pharmacological agents are under investigation aiming to reduce growth and prevent AAA rupture. These drugs target different pathological pathways and, notably, the excessive production of prostanoids by cyclooxygenases (COX). Intra-aneurysmal thrombus plays an adverse key role in the progression of AAA, platelets being a primary source of prostanoids as thromboxane A2. OBJECTIVE: In this review, we summarize studies targeting prostanoids production and down-stream pathways in cardiovascular diseases, and more specifically in AAA. RESULTS AND CONCLUSION: Various inhibitors of COX or antagonists of prostanoids receptors have been investigated in AAA animal models with conflicting results. In human AAA, only a few number of studies focused on anti-platelet therapy mostly using acetylsalicylic acid (aspirin, ASA), a COX1 inhibitor. Finally, we report preliminary promising results of a model of AAA in rats receiving a thromboxane A2 inhibitor, BM-573 that induced a reduction of aneurysmal growth.

Dopaminergic neurons differentiating from LRRK2 G2019S induced pluripotent stem cells show early neuritic branching defects.

Some mutations of the LRRK2 gene underlie autosomal dominant form of Parkinson's disease (PD). The G2019S is a common mutation that accounts for about 2% of PD cases. To understand the pathophysiology of this mutation and its possible developmental implications, we developed an in vitro assay to model PD with human induced pluripotent stem cells (hiPSCs) reprogrammed from skin fibroblasts of PD patients suffering from the LRKK2 G2019S mutation. We differentiated the hiPSCs into neural stem cells (NSCs) and further into dopaminergic neurons. Here we show that NSCs bearing the mutation tend to differentiate less efficiently into dopaminergic neurons and that the latter exhibit significant branching defects as compared to their controls.

p27(Kip1) is a microtubule-associated protein that promotes microtubule polymerization during neuron migration.

The migration of cortical interneurons is characterized by extensive morphological changes that result from successive cycles of nucleokinesis and neurite branching. Their molecular bases remain elusive, and the present work describes how p27(Kip1) controls cell-cycle-unrelated signaling pathways to regulate these morphological remodelings. Live imaging reveals that interneurons lacking p27(Kip1) show delayed tangential migration resulting from defects in both nucleokinesis and dynamic branching of the leading process. At the molecular level, p27(Kip1) is a microtubule-associated protein that promotes polymerization of microtubules in extending neurites, thereby contributing to tangential migration. Furthermore, we show that p27(Kip1) controls actomyosin contractions that drive both forward translocation of the nucleus and growth cone splitting. Thus, p27(Kip1) cell-autonomously controls nucleokinesis and neurite branching by regulating both actin and microtubule cytoskeletons.