Müller cells in allogeneic adult rabbit retinal transplants

Star-cross'd neurons: astroglial effects on neural repair in the adult mammalian CNS

Astroglia have long been thought to play merely a supporting role in the life of the neuron. However, these star-shaped cells have recently been the focus of intense study that has begun to emphasize remarkable and novel roles for these amazing cells. While astroglia play positive roles in the life of the neuron, they can simultaneously exert negative influences. Kinouchi et al. convincingly demonstrate and characterize an inhibitory role played by astroglia after neuronal transplantation. These findings remind us that astroglia exert positive and negative influences on neuronal survival, migration, neurite outgrowth and functional integration. Here, we review the complementary and often contradictory roles of astroglia during neuronal integration.

Robust neural integration from retinal transplants in mice deficient in GFAP and vimentin

With recent progress in neuroscience and stem-cell research, neural transplantation has emerged as a promising therapy for treating CNS diseases. The success of transplantation has been limited, however, by the restricted ability of neural implants to survive and establish neuronal connections with the host. Little is known about the mechanisms responsible for this failure. Neural implantation triggers reactive gliosis, a process accompanied by upregulation of intermediate filaments in astrocytes and formation of astroglial scar tissue. Here we show that the retinas of adult mice deficient in glial fibrillary acidic protein and vimentin, and consequently lacking intermediate filaments in reactive astrocytes and Müller cells, provide a permissive environment for grafted neurons to migrate and extend neurites. The transplanted cells integrated robustly into the host retina with distinct neuronal identity and appropriate neuronal projections. Our results indicate an essential role for reactive astroglial cells in preventing neural graft integration after transplantation.