Efficient in vivo protection of nigral dopaminergic neurons by lentiviral gene transfer of a modified Neurturin construct

The isolation of neural stem cells from the olfactory bulb of Parkinson's disease model

Hyposmia is one of the characteristic symptoms of PD. We isolated the neurosphere forming cells (NSFCs) from the olfactory bulb (OB) after dopaminergic neuronal loss induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which is a model of Parkinson's disease. We used BrdU to label dividing cells and isolated NSFCs from the OB of adult mice with or without MPTP to confirm the function of OB in PD models. Seven days after MPTP treatment, BrdU-positive cells were significantly increased in the OB, especially in the glomerular layer (GL) and the subependymal zone (SEZ). The number of neurospheres derived from the adult OB was not decreased in groups receiving MPTP, instead, it was significantly increased at 21 days post-injection and only returned to control levels 40 days after MPTP administration. We also evaluated the differentiation of NSFCs into neural subtypes and found that these NSFCs could be well infected with retrovirus. Adult neurogenesis may be enhanced as a repair system in the tyrosine hydroxylase (TH) positive cells of the OB after MPTP administration. The isolation of neural stem cells from the OB after MPTP administration has helped to establish the cellular basis of neurogenesis and supports a role for the transplant-mediated treatment of PD.

Gene transfer therapy for neurodegenerative disorders

Recent advances in gene transfer technology have led to promising new therapies for neurodegenerative disorders. This article will review methods of gene transfer therapy and applications of these techniques to both genetic and sporadic neurodegenerative illnesses. The article will focus on Parkinson's disease, Huntington's disease, and Alzheimer's disease. Several promising gene therapy approaches to these diseases are being pursued both in animal models and in early human trials. Initial safety-tolerability results from these trials appear promising. It is therefore likely that the number of human trials of gene therapy for neurodegenerative disorders will increase over the coming years.

Autotransplantation of bone marrow-derived stem cells as a therapy for neurodegenerative diseases

Neurodegenerative diseases are characterized by a progressive degeneration of selective neural populations. This selective hallmark pathology and the lack of effective treatment modalities make these diseases appropriate candidates for cell therapy. Bone marrow-derived mesenchymal stem cells (MSCs) are self-renewing precursors that reside in the bone marrow and may further be exploited for autologous transplantation. Autologous transplantation of MSCs entirely circumvents the problem of immune rejection, does not cause the formation of teratomas, and raises very few ethical or political concerns. More than a few studies showed that transplantation of MSCs resulted in clinical improvement. However, the exact mechanisms responsible for the beneficial outcome have yet to be defined. Possible rationalizations include cell replacement, trophic factors delivery, and immunomodulation. Cell replacement theory is based on the idea that replacement of degenerated neural cells with alternative functioning cells induces long-lasting clinical improvement. It is reasoned that the transplanted cells survive, integrate into the endogenous neural network, and lead to functional improvement. Trophic factor delivery presents a more practical short-term approach. According to this approach, MSC effectiveness may be credited to the production of neurotrophic factors that support neuronal cell survival, induce endogenous cell proliferation, and promote nerve fiber regeneration at sites of injury. The third potential mechanism of action is supported by the recent reports claiming that neuroinflammatory mechanisms play an important role in the pathogenesis of neurodegenerative disorders. Thus, inhibiting chronic inflammatory stress might explain the beneficial effects induced by MSC transplantation. Here, we assemble evidence that supports each theory and review the latest studies that have placed MSC transplantation into the spotlight of biomedical research.

Emerging drugs for Parkinson’s disease

Parkinson's disease (PD) afflicts millions of people worldwide. There are numerous drugs available for PD; however, levodopa remains the gold standard of pharmacotherapy to which all other therapies are compared. Levodopa is quite effective for many motor symptoms (bradykinesia, tremor, rigidity) of PD; however, non-levodopa-responsive motor symptoms (postural instability) and nonmotor symptoms are frequently the most troublesome in middle and later stages of disease. Although motor symptoms remain an important focus for emerging drugs, current research is largely geared to identify and develop disease-slowing therapies. Another important area of focus has become treatment of the nonmotor symptoms of PD (especially depression and dementia). This review discusses emerging drugs in the management of the motor and nonmotor symptoms of PD and drugs under study as disease-slowing/neuroprotective agents.

Current and future treatments in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is an atypical parkinsonian disorder that, in spite of its growing recognition, is still underdiagnosed. For management, prognosis, and research, an accurate and early diagnosis is essential. PSP is a relentlessly progressive neurodegenerative disorder, clinically characterized by parkinsonism with prominent axial involvement and postural instability, bulbar symptoms, supranuclear ophthalmoplegia, and executive dysfunction. Abnormal neuronal and glial four-repeat tau aggregations affecting the basal ganglia and selective brainstem structures result in dysfunction of the five frontosubcortical circuits and brainstem functions. Primary therapeutic approaches are based on neurotransmitter replacement and palliative strategies. This article reviews the experience and challenges with neurotransmitter replacement and palliative strategies through an extensive literature search of studies published between 1965 and 2005. The role of and limited experience with alternative therapies, such as deep brain stimulation and pallidotomy, are also discussed. Advances in the development of biological therapies for PSP and a better understanding of its etiopathogenesis will likely result from epidemiologic studies and developed four-repeat tau-transgenic animal models. The management of patients with this disorder poses a considerable challenge and includes symptomatic and palliative strategies, as well as education and support, to improve the quality of life for patients and their caregivers.

Human gene therapy and imaging in neurological diseases

Molecular imaging aims to assess non-invasively disease-specific biological and molecular processes in animal models and humans in vivo. Apart from precise anatomical localisation and quantification, the most intriguing advantage of such imaging is the opportunity it provides to investigate the time course (dynamics) of disease-specific molecular events in the intact organism. Further, molecular imaging can be used to address basic scientific questions, e.g. transcriptional regulation, signal transduction or protein/protein interaction, and will be essential in developing treatment strategies based on gene therapy. Most importantly, molecular imaging is a key technology in translational research, helping to develop experimental protocols which may later be applied to human patients. Over the past 20 years, imaging based on positron emission tomography (PET) and magnetic resonance imaging (MRI) has been employed for the assessment and "phenotyping" of various neurological diseases, including cerebral ischaemia, neurodegeneration and brain gliomas. While in the past neuro-anatomical studies had to be performed post mortem, molecular imaging has ushered in the era of in vivo functional neuro-anatomy by allowing neuroscience to image structure, function, metabolism and molecular processes of the central nervous system in vivo in both health and disease. Recently, PET and MRI have been successfully utilised together in the non-invasive assessment of gene transfer and gene therapy in humans. To assess the efficiency of gene transfer, the same markers are being used in animals and humans, and have been applied for phenotyping human disease. Here, we review the imaging hallmarks of focal and disseminated neurological diseases, such as cerebral ischaemia, neurodegeneration and glioblastoma multiforme, as well as the attempts to translate gene therapy's experimental knowledge into clinical applications and the way in which this process is being promoted through the use of novel imaging approaches.