ABSTRACT
Genetic diseases of the brain usually have pathologic lesions distributed throughout, thus requiring global correction. Herpes simplex virus-1 (HSV-1) vectors may be especially useful for gene delivery in these disorders since they can spread trans-synaptically along neuronal pathways to distal sites from a localized injection. We have previously shown that a nonpathogenic HSV-1 (strain 1716), which is deleted in the ICP34.5 gene, and expressing the lysosomal enzyme ß-glucuronidase (GUSB) from the latency-associated transcript (LAT) promoter, spreads within the brains of GUSB-deficient mucopolysaccharidosis VII mice to reverse the pathognomonic storage lesions throughout the diseased brain. In this study, we tested the ability of the 1716 LAT-GUSB vector to improve behavioral deficits. The treatment significantly decreased anxiogenic behaviors associated with the mutation, as indicated by open-field behavior and decreased neophobia in a novel object-recognition task. The treated mice also exhibited an improvement in cognitive function associated with the cerebral cortex in a familiar object test. The results indicate the functional therapeutic potential of the 1716 LAT-GUSB vector.
ABSTRACT
Pluripotent embryonic stem (ES) cells are the most versatile cells, with the potential to differentiate into all types of cells. However, the cellular and molecular mechanisms responsible for their differentiation into specific lineages have not been elucidated. Recent studies in human ES cells have challenged the scientific community to focus research on the basic mechanisms of stem cell differentiation for their potential applications in regenerative medicine and cell-based therapies. The majority of studies thus far have focused on cells that are already committed to specific lineages. The current studies were designed to establish a system for investigating the mechanisms of cell fate determination starting from undifferentiated ES cells, to gain insight into events during the normally inaccessible period of development. Here we demonstrate that pluripotent ES cells can be programmed to differentiate into chondrocytes, the cartilage-producing cells, by co-culture with progenitor cells from the limb buds of the developing embryo. Almost 60%-80% of the cells exhibited phenotypic characteristics of mature chondrocytes and expressed genes such as sox9, collagen type II, and proteoglycans, which was accompanied by a decrease in ES cell-specific transcription factor Oct-4. Collagen type II, which is expressed in two different forms during chondrogenic differentiation due to the alternate splicing of mRNA, was also properly regulated. The studies presented here suggest that the signals produced by progenitor cells from the developing embryo can induce lineage-specific differentiation. The system described here may serve as an in vitro model to study the mechanisms of cell fate determination by stem cells.
