Background and Purpose-Choroid plexus (CP) secretes a cocktail of neurotrophic factors. In the present study, CP from neonatal pigs was encapsulated within alginate microcapsules for in vitro and in vivo neuroprotective studies. Methods-In vitro studies involved serum deprivation of rat embryonic cortical neurons and treatment with a range of concentrations of conditioned media from CP. For in vivo studies, rats received a 1-hour middle cerebral artery occlusion followed by intracranial transplantation of encapsulated or unencapsulated CP, empty capsules, or no transplant. Behavioral testing was conducted on days 1 to 3 after transplantation. Cerebral infarction was analyzed using 2,3,5-triphenyl-tetrazolium chloride staining at 3 days after transplantation. Results-Conditioned media from CP produced a significant dose-dependent protection of serum-deprived cortical neurons. Enzyme-linked immunosorbent assay confirmed secretion of GDNF, BDNF, and NGF from CP. Parallel in vivo studies showed that CP transplants improved behavioral performance and decreased the volume of infarction. Both encapsulated and unencapsulated CP transplants were effective; however, more robust benefits accompanied encapsulated transplants. Conclusions-These data are the first to demonstrate the neuroprotective potential of transplanted CP and raise the intriguing possibility of using these cells as part of the treatment regimen for stroke and other neurological disorders.

Insulin-like growth factor (IGF)-1, IGF binding protein (IGFBP)-2, and IGFBP-3 are expressed in the rat brain in regions of neuronal loss by 3 days after hypoxic- ischemic (HI) brain injury and IGF-2 somewhat later. Central administration of rh-IGF-1 after HI injury reduces neuronal loss in vivo. To clarify the mode of action of IGF-1 and the potential role of IGFBPs, the effects of IGF-1, IGF-2, des(1-3)-N-IGF-1 (des-IGF-1), an analogue of IGF-1 with low affinity for IGFBPs, and IGF-1 combined with IGF-2 were compared 2 h after administration into the lateral cerebral ventricle after an HI injury. Unilateral HI was induced in adult rats by right carotid artery ligation followed by 10- min exposure to 6%O2. The extent of neuronal loss was determined in the cortex, striatum, hippocampus, dentate gyrus, and thalamus 5 days later. Central administration of 20 micrograms IGF-1 (n = 17) reduced neuronal loss in all regions (P < 0.01). Neither 20 micrograms IGF-2 (n = 17), 2 micrograms des-IGF-1 (n = 10), nor 20 micrograms des-IGF-1 (n = 17) reduced neuronal loss. There was a trend towards a reduction in neuronal loss after 150 micrograms des-IGF-1 (n = 20). IGF-2 alone increased neuronal loss in the hippocampus and dentate gyrus compared with the same regions in vehicle-treated animals (P < 0.05). Coadministration of 30 micrograms IGF-2 blocked the neuroprotective effects of 20 micrograms IGF-1 (n = 18, P < 0.05) and reduced the accumulation of [3H]IGF-1 in the injured hemisphere (n = 4) (P < 0.05). These observations suggest a role for IGFBPs in targeting the neuroprotective actions of IGF-1. IGF-2 may antagonize the protective effect of IGF-1 by displacing it from IGFBPs.

Transforming growth factor-beta (TGF-beta) is formed in the airways and may have a role in airway remodeling in asthma. We have studied the effects of TGF-beta on bovine airway smooth muscle cells (BASMC) in vitro. Thymidine incorporation by BASMC was inhibited after a 24-h incubation with TGF-beta 1. In contrast, thymidine incorporation by BASMC was stimulated (35.1 +/- 11.2%) after a 48-h incubation with 1 ng/ml TGF-beta 1. Cell number was also increased (25.9 +/- 7.6%) after a 72-h incubation with 3 ng/ml TGF-beta 1. TGF-beta 1 also increased cell size at 72 h, with a 24.3 +/- 6.2% increase in cell, diameter. Increases in BASMC size were accompanied by increased [3H]proline incorporation into cell protein. In cells from any individual animal, there was a strong inverse correlation (r = -0.97) between changes in cell number and cell size. In cells from some animals, the main effect of TGF-beta 1 was to promote an increase in cell number, whereas in others the predominant effect was cell hypertrophy. In contrast epidermal growth factor (EGF) led to an increase in thymidine incorporation and cell number in all preparations but did not increase cell size. TGF-beta 1 also promoted secretion of glycosaminoglycans into culture medium by BASMC with a preferential increase in hyaluronan secretion (4.5-fold) after 24 h. Latent TGF-beta (0.89 +/- 0.06 ng/ml) was also detected in conditioned medium from cultured BASMC, and TGF-beta 1 expression was demonstrated with RNA extracts from BASMC. Varying degrees of both smooth muscle cell hypertrophy and hyperplasia occur in asthma. These results obtained with airway smooth muscle cells indicate that TGF-beta could play a role in the structural changes seen in asthma.

Insulin-like growth factor 1 (IGF-1) plays a critical role in CNS development. IGF-1 can block neuronal apoptosis in vitro and in vivo. IGF-1 is thought to be cleaved into des-N-(1-3)-IGF-1 and an amino terminal glycine-proline-glutamate (GPE tripeptide). Here we report a neuroprotective role for GPE tripeptide, with enhanced survival of the CA1-2 hippocampal neurons following an excitotoxic insult in vitro. Binding and displacement studies suggest uniquely distributed sites of action within the rat including the hippocampal CA1-2, pyriform cortex, amygdala, choroid plexus, blood vessels and to a lesser extent in the cortical regions. A similar pattern of binding was seen in the human. This finding could lead to new strategies to reduce neuronal death after injury and in disease.

The present study examined the neuroprotective effects of choroid plexus isolated from adult rats and encapsulated within alginate microcapsules. In vitro, conditioned media from cultured choroid plexus produced a marked, dose-dependent protection of embryonic cortical neurons against serum deprivation-induced cell death. In vivo studies demonstrated that a one-hour middle cerebral artery occlusion in adult Wistar rats produced profound motor and neurological impairments 1-3 days after stroke. In contrast, stroke animals transplanted with encapsulated choroid plexus cells displayed a significant reduction in both motor and neurological abnormalities. Histological analysis 3 days post-transplantation revealed that choroid plexus transplants significantly decreased the volume of striatal infarction. This is the first report demonstrating the therapeutic potential of transplanted choroid plexus for stroke.