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Ventral mesencephalic (VM) precursor cells are of interest in the search for transplantable dopaminergic neurons for cell therapy in Parkinson's disease (PD). In the present study we investigated the survival and functional capacity of in vitro expanded, primary VM precursor cells after intrastriatal grafting to a rat model of PD. Embryonic day 12 rat VM tissue was mechanically dissociated and cultured for 4 or 8 days in vitro (DIV) in the presence of FGF2 (20 ng/ml), FGF8 (20 ng/ml) or without mitogens (control). Cells were thereafter differentiated for 6 DIV by mitogen withdrawal and addition of serum. After differentiation, significantly more tyrosine hydroxylase-immunoreactive (TH-ir), dopamine-producing neurons were found in FGF2- and FGF8-expanded cultures compared to controls. Moreover, expansion for 4 DIV resulted in significantly more TH-ir cells than expansion for 8 DIV both for FGF2 (2.4 fold; P<0.001) and FGF8 (3.8 fold; P<0.001) treated cultures. The functional potential of the expanded cells (4 DIV) was examined after grafting into striatum of aged 6-hydroxydopamine-lesioned rats. Amphetamine-induced rotations performed 3, 6 and 9 weeks postgrafting revealed that grafts of FGF2-expanded cells induced a significantly faster and better functional recovery than grafts of FGF8-expanded cells or control cells (P<0.05 for both). Grafts of FGF2-expanded cells also contained significantly more TH-ir cells than grafts of FGF8-expanded cells (P<0.05) or control cells (P<0.01). In conclusion, FGF2-mediated pregrafting expansion of primary VM precursor cells considerably improves dopaminergic cell survival and functional restoration in a rat model of PD.

Transplantation of bone marrow stromal cells (BMSC) has recently been demonstrated to provide neuroprotection in animal models of brain injuries such as ischemia and trauma. The present study was undertaken to explore whether BMSC can promote the survival of dopamine (DA) neurons in neuronal insult models in vitro. We also examined whether BMSC can increase the survival rate of embryonic DA neurons grafted into the striatum of a rat model of Parkinson's disease (PD). Treatment with conditioned media derived from BMSC cultures was found to significantly prevent the death of DA neurons in in vitro cell injury models such as serum deprivation and exposure to the neurotoxin 6-OHDA. In a transplantation study, we also found that the survival of grafted DA cells was significantly enhanced by treating donor cells with the conditioned media at the steps of both cell dissociation and implantation. The results suggest that BMSC may secrete diffusible factors able to protect DA neurons against neuronal injuries. Indeed, BMSC expressed mRNA encoding brain-derived neurotrophic factor, fibroblast growth factor-2 and glial cell line-derived neurotrophic factor, all of which have previously been shown to exhibit potent neurotrophic effects on DA cells. Enzyme-linked immunosorbent assay revealed that the cells release these growth factors into culture media. The present data indicate that BMSC may be a potential donor source of cell-based regenerative therapy for PD where the progressive loss of the midbrain DA neurons takes place.

Bilateral astroglial transplantation into the neostriatum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys resulted in significant performance improvement in a spatial delayed response task, but failed to modify perseveration in an object retrieval detour task, or to improve motor clinical rating. Results suggest that brain circuits subserving various motor and cognitive performances can be functionally dissociated, and that remaining resources for the reorganization of neural circuits involved in spatial working memory performance in parkinsonian monkeys, appear to be responsive to striatal transplantation of subcultured, fetal striatal astroglial cells.

Rats were given unilateral 6-hydroxydopamine (6-OHDA) lesions and subsequently received transplants of fetal ventral mesencephalic tissue into the denervated striatum. Four weeks later transplanted animals were tested for graft-mediated reduction of amphetamine-induced rotational behavior. Subsequently, transplanted animals received an intrastriatal injection of either GDNF (10 microg) or citrate buffer into a site lateral to the transplant, and then 6 h later received an injection of either 4.0 microg of 6-OHDA, 8.0 microg of 6-OHDA, or vehicle using the same stereotaxic coordinates that were used for the GDNF/citrate buffer injection. Animals were re-tested for amphetamine-induced rotational behavior 2 weeks later. Histological analysis revealed a significant reduction in the number of cell bodies immunostained for tyrosine hydroxylase (TH+) within the transplant for those animals pretreated with an intrastriatal injection of citrate buffer and subsequently given either dose of 6-OHDA. Transplanted animals pretreated with GDNF and subsequently administered 8.0 microg of 6-OHDA showed a significant reduction of TH+ neurons within the transplant compared to controls, however TH+ cell counts for this group remained significantly higher than the TH+ cell counts for the group of animals receiving the same dose of 6-OHDA but pretreated with citrate buffer. GDNF pretreatment completely protected TH+ cell bodies against 4.0 microg of 6-OHDA. Rotational scores indicated that GDNF provided only partial protection against 6-OHDA neurotoxicity in terms of transplant function. For both groups of transplanted animals receiving GDNF pretreatment and 6-OHDA injections, amphetamine-induced rotational scores dropped below the scores for animals pretreated with citrate buffer but remained significantly higher than the scores for transplanted animals that were not injected with 6-OHDA. Both histological and behavioral measures indicate GDNF partially protects integrated transplants against neurotoxic insult.

Recently, we have shown that rapid eye movement sleep deprivation (REM-SD) in animals with lesions of the nigro-striatal pathway facilitates turning behavior and such increase still occurred even in the presence of dopaminergic grafts. The objective of this work was to determine which DA receptors are preferentially involved. The results showed that the D2 receptor antagonist sulpiride decreases significantly turning behavior of lesioned animals, with no effect whatsoever of the D1 antagonist SCH 23390. When lesioned animals were REM sleep deprived, the D1 but not the D2 receptor antagonist prevented the increase of turning induced by REM-SD. This work suggests that the increase of post-synaptic supersensitivity induced by REM-SD in nigro-striatal lesioned animals is mediated by D1 receptors.