Nina Kosi, Ivan Alic, Srecko Gajovic and Dinko Mitrecic
Laboratory for Stem Cells, Croatian Institute for Brain Research, University of Zagreb, Croatia
To reach a satisfactory level of survival and healing properties, it is hypothesized that transplanted neural stem cells (NSCs) need to enter the process of formation of synaptic contacts with both host neurons and in-between themselves. Thus we induced ischemic brain injury by middle cerebral artery occlusion in C57/Bl6 mice, labeled cells with a fluorescent dye and stereotactically injected them 5 days after injury at the dorsal cortico-callosal boundary. Animals were sacrificed at 2, 4, 8 and 14 weeks following transplantation and we analyzed expression of Cell adhesion molecule 1 (CADM1), Neuroligin 1 (NLGN1) and Synapsin I (SYN1). Migration of transplanted NSCs from the implantation site to the site of the lesion was observed and cells aggregated robustly in the ischemic core. They were positive for Nestin, and majority of them for CADM1 and Neuroligin 1. No SYN1 staining was present, even after 14 weeks. This in vivo observed pattern was similar to our in vitro results. NSCs are exhibiting a marked and early visible potential for interaction with other cells and extracellular matrix which suggests that formation of synapses contributes to survival, integration and healing properties of NSCs.
Keywords: Neural stem cells, stroke, MCAO, synapse.