Novel gene therapeutic strategies for neurodegenerative diseases.

The convergent pathobiologic model of Parkinson's disease stipulates that disparate insults initiate a disease process that obligately share a common pathway leading to cell death. A combinatorial treatment which targets various steps in this pathway is likely to be the most successful therapeutic strategy. As advances are made in the field of neuroimaging and pharmacogenomics, early detection of sporadic PD will become a reality. Early intervention will likely spare more dopaminergic neurons and extend the quality of life for the patient. Continued advancements in the fields of pharmacology, neurosurgery, and gene therapy will strengthen the armamentarium available for the treatment of PD patients.

Calbindin D28k mRNA in hippocampus, superior temporal gyrus and cerebellum: comparison between control and Alzheimer disease subjects.

To further investigate the role of calbindin D28k in Alzheimer's disease (AD); hippocampus, superior temporal gyrus and cerebellum from control and AD cases were examined by quantitative in situ hybridization. We report here a decrease in CaBD28k mRNA in the CA2 region of AD hippocampus compared to control subjects. There were no significant differences between AD and control subjects in the other regions studied.

HSV vector-mediated gene delivery to the central nervous system.

The efficient and targeted transfer of genes is the goal of gene therapy. In the central nervous system (CNS), this is challenging due in part to the exquisite anatomy of the brain. Herpes simplex virus (HSV) vectors are particularly amenable to CNS therapies as they are capable of transducing a variety of cells, have a large transgene capacity and can exist as either oncolytic or non-immunogenic vectors. The versatility of this vector platform and its potential molecular therapeutic use in two CNS disorders, Alzheimer's disease and malignant brain tumors, will be discussed.

Preferential loss of preproenkephalin versus preprotachykinin neurons from the striatum of Huntington's disease patients.

Preferential loss of basal ganglia neurons and terminals occurs in Huntington's disease (HD). Terminals of preproenkephalin medium-size spiny neurons are more vulnerable than terminals of preprotachykinin neurons, but the peptidergic neurons of origin have not yet been shown to die preferentially. We sought to determine, in the striatum, whether preproenkephalin neurons were lost to a greater extent than preprotachykinin neurons and to determine whether there were decreases in specific messenger RNA (mRNA) levels of preproenkephalin, preprotachykinin, and calbindin D28k. We found a grade-related decrease in the number of preprotachykinin- and calbindin D28k-labeled neurons per measuring field in the caudate nucleus of patients with HD. Three measures of the neuronal level of preprotachykinin mRNA were all significantly reduced (6-65% of control values) in HD caudate nucleus. No decline in calbindin D28k mRNA levels per neuron were found in HD striata compared to control striata. We found a greater loss of preproenkephalin neurons per field than preprotachyknin neurons per field in the caudate nucleus of HD brains compared to control brains. Preprotachykinin neurons are lost in HD in a grade-related manner and surviving preprotachykinin neurons are impaired in function. However, preproenkephalin neurons are lost to a greater extent than preprotachykinin neurons, which may explain preferential changes found in projection regions of the striatum. Declines in neuropeptide mRNA may be specific in HD, since calbindin D28k mRNA levels were unchanged. Alterations in the levels of expression of preproenkephalin and preprotachykinin mRNA may be direct or indirect effects of the HD mutation.

Reduced expression of preproenkephalin in striatal neurons from Huntington's disease patients.

Differential loss of neurons and terminals occurs in Huntington's disease. Neurons expressing preproenkephalin (PPE) appear to be more vulnerable than neurons expressing preprotachykinin and terminals in the lateral pallidum (containing enkephalin) are more affected than terminals in the medial pallidum (containing substance P). We used in situ hybridization histochemistry and emulsion autoradiography to quantify the number of PPE expressing neurons and the neuronal levels of PPE mRNA in striatum of individuals who died with Huntington's disease and normal controls. We found a grade-related decline in the number of PPE-labeled neurons per field in the striatum of individuals with Huntington's disease compared with controls. Three measures of the neuronal level of PPE mRNA, the mean number of silver grains per PPE neuron, the median number of grains per PPE neuron, and the percentage of PPE neurons with more than 30 grains, were all significantly reduced (41 to 80% of control) in Huntington's disease striatum. The magnitude of the reduction in levels of PPE mRNA per neuron was related to the grade of lesions. These data support the notion that decreased levels of PPE mRNA may account, in part, for the greater loss of enkephalin staining in lateral pallidal terminals compared with substance P staining in medial pallidal terminals. Decreased levels of PPE mRNA may result in clinical symptoms prior to the loss of neurons. The reduction in expression of PPE mRNA suggests that surviving striatal neurons may be affected by the expression of the Huntington's disease gene prior to their imminent cell death.