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Gene and Cell therapies have paved the way to a new era in the treatment of human diseases. Knowledge about the potentiality and limits of such therapeutical tools is of great interest. The use of antisense oligonucleotides and more recently, of small interfering RNAs (siRNAs) as selective inhibitors of gene expression, offers a rational approach to the prevention and treatment of some gene-mediated disorders. In this gene therapy approach, oligonucleotides or siRNAs block the expression of specific target genes involved in the development of the pathological processes. The use of antisense molecules to modify gene expression has been found to be variable in its efficacy and reliability, raising objections about their use as therapeutic agents. However, several antisense candidate molecules are undergoing separate clinical trials. It is still too early to tell whether the entire class of antisense drugs will prove to be clinically effective. It is, however, quite surprising that all efforts devoted to clinical trials of dozens of antisense compounds have so far produced only a commercial drug, targeted against a side effect of HIV infection and hence, with a limited market value. Nevertheless, the antisense oligonucleotides could be one of the few strategies that could be used to treat some neurodegenerative diseases. In this issue, some contributions discuss the promises and concerns linked to the development of a new generation of antisense molecules for treatment of neural diseases. Concerns about antisense therapeutics have induced researchers to focus on other gene therapy tools. Gene expression downregulation by siRNAs (the so called RNA interference) is one of the most exciting discoveries of the past decade in functional genomics. Some authors have reported that the potency, effectiveness, duration of action, and sequence specificity of siRNAs are greater than those obtained with antisense molecules. For this reason, RNA interference is rapidly becoming an important method for analyzing gene functions in eukaryotes, and promises the development of therapeutic gene silencing. This topic is also discussed in this issue. Stem cell therapy seeks to reverse the ravages of damaged tissues by injecting living stem cells from animal organs, embryos or fetuses into patients. Traditional cell therapy is founded on the belief that, when healthy cells are injected into patients, cells will automatically find their way to damaged tissues and stimulate the body's own healing process. For example, there is evidence that liver stem cells injected into the human body naturally migrate to the host liver and stimulate regeneration. Stem cell therapy is promoted as an alternative therapy for several pathologies, such as cancer, atherosclerosis, and several neurodegenerative diseases. Unfortunately, there are a number of potential side effects regarding which, the individuals considering this therapy should be made aware. Indeed, cell therapy may be dangerous and some cases in medical literature reported of patient deaths directly linked to the therapy. Patients may contract bacterial and viral infections carried by the donor cells, and have experienced life-threatening and even fatal allergic reactions. Donor cells may seriously compromise the immune system. Thus, despite extensive research, still there are problems with stem cell therapy, since in many cases, deep and exhaustive studies to find out the exact biology of stem cells are omitted, and there are increasing pressures to start with insufficiently controlled clinical trials. It is very important to address all these issues, and therefore, some contributions are focused on these key topics and give an in-depth contribution to the knowledge of the state of art in cell therapy, with particular emphasis on the treatment of neural diseases.