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Implantation of Polymer-Encapsulated Human Nerve Growth Factor-Secreting Fibroblasts Attenuates the Behavioral and Neuropathological Consequences of Quinolinic Acid Injections into Rodent Striatum

Delivery of neurotrophic molecules to the central nervous system has gained considerable attention as a potential strategy for the treatment of neurological disorders. In the present study, a DHFR-based expression vector containing the human nerve growth factor gene (hNGF) was transfected into a baby hamster fibroblast cell line (BHK). Using an immunoisolatory polymeric device, encapsulated BHK-control cells and those secreting hNGF (BHK-hNGF) were transplanted unilaterally into rat lateral ventricles. Three days later, the same animals received unilateral injections of quinolinic acid (QA, 225 nmol) or the saline vehicle into the ipsilateral striatum. Approximately 2 weeks following surgery, animals were tested for apomorphine-induced rotation behavior. Animals which received BHK-hNGF cells rotated significantly less than those animals receiving BHK-control cells or QA alone. Histological analysis 29-30 days following capsule implantation demonstrated that BHK-hNGF cells attenuated the extent of host neural damage produced by QA as assessed by a sparing of ChAT- and NADPH-d-positive neurons. Moreover, a lessened GFAP reaction was apparent within the striatum of animals receiving BHK-hNGF cells. As measured by ELISA, hNGF was released by the encapsulated BHK-hNGF cells prior to implantation and following removal. Morphology of retrieved capsules revealed numerous viable and mitotically active BHK cells. These results suggest that implantation of polymer-encapsulated hNGF-releasing cells can be used to protect neurons from excitotoxin damage.