Neural stem cells: an overview.

Multipotent stem cells are present in the majority of mammalian tissues where they are a renewable source of specialized cells. According to the several biological portions from which multipotent stem cells can be derived, they are characterized as a) embryonic stem cells (ESCs) isolated from the pluripotent inner-cell mass of the pre-implantation blastocyste-stage embryo; b) multipotent fetal stem cells (FSCs) from aborted fetuses; and c) adult stem cells (ASCs) localized in small zones of several organs known as "niche" where a subset of tissue cells and extracellular substrates can indefinitely house one or more stem cells and control their self-renewal and progeny production in vivo. ECSs have an high self-renewing capacity, plasticity and pluripotency over the years. Pluripotency is a property that makes a stem cell able to give rise to all cell type found in the embryo and adult animals.

Neural stem cells. Biological features and therapeutic potential in Parkinson's disease.

AIM: Neural stem cells (NSC) are clonogenic cells, capable of self-renewal and multilineage differentiation, since, under the appropriated experimental conditions, they proliferate indefinitely as undifferentiated neurospheres or differentiate in neurons, astrocytes and oligodendrocytes. Parkinson's disease is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons. METHODS: Here we investigated the suitability of recently identified and characterized neuronal progenitor cells at eliciting functional recovery in unilateral 6HODA-lesioned mice. We describe herein that intrastriatal engraftment of stem cell-derived neurons isolated from the olfactory bulb to give rise dopaminergic-like neurons results in long lasting functional recovery in 6OHDA-injured mice. RESULTS: Unilateral injection of 6OHDA resulted in a progressive neurodegeneration of the nigro-striatal pathway. Likewise, the systemic administration of L-DOPA in these mice elicited a marked contralateral turning which was evident 1 week post, increased during the following week and than stabilize throughout the time of the experiment. Conversely, the intrastriatal implantation of partially differentiated stem cells at 14 days postlesion, resulted in a profound decrease in L-DOPA-induced circling behavior; interestingly, the effect was evident 1 week after the engraftment and was retained during the following 9 weeks. Detailed biochemical and immunohistochemical evaluation is currently under investigation in our laboratory. Conclusion. Our observation opens new perspectives for the treatment of neurodegeneration in Parkinson's disease.

Human developing motor neurons as a tool to study ALS.

Defining the basis of the selective cell vulnerability of human motor neurons (hMNs) represents a crucial step in revealing the pathogenesis of amyotrophic lateral sclerosis (ALS). Tissue culture models offer an ideal system for identification of the hMN-specific features at the single cell level. Purified hMNs and astrocytes can today be isolated from the anterior horn of the human embryonic spinal cord. Cultures can be studied at the single cell level using cDNA/mRNA amplification techniques. The effects of molecules affecting hMN survival, neurite extension, and metabolism can be tested in vitro and the expression of selective genes assayed using DNA microarray technology. Crucial information of immediate clinical application for the treatment of patients affected by ALS can be derived after testing the efficacy of candidate pharmaceutical molecules using in vitro cell models. Adult nervous tissue or progenitor cells derived from different regions of the nervous system may be used as an alternative source of human neuronal cells. HMNs in culture, combined with the application of adequate technology, can contribute greatly to identifying the primitive critical events responsible for the cell degeneration observed in ALS, bypassing the intrinsic limitations of the non-human models of the disease.