Long-Term Survival of Human Neural Stem Cells in the Ischemic Rat Brain upon Transient Immunosuppression

Abstract

Understanding the physiology of human neural stem cells (hNSCs) in the context of cell therapy for neurodegenerative disorders is of paramount importance, yet large-scale studies are hampered by the slow-expansion rate of these cells. To overcome this issue, we previously established immortal, non-transformed, telencephalic-diencephalic hNSCs (IhNSCs) from the fetal brain. Here, we investigated the fate of these IhNSC's immediate progeny (i.e. neural progenitors; IhNSC-Ps) upon unilateral implantation into the corpus callosum or the hippocampal fissure of adult rat brain, 3 days after global ischemic injury. One month after grafting, approximately one fifth of the IhNSC-Ps had survived and migrated through the corpus callosum, into the cortex or throughout the dentate gyrus of the hippocampus. By the fourth month, they had reached the ipsilateral subventricular zone, CA1-3 hippocampal layers and the controlateral hemisphere. Notably, these results could be accomplished using transient immunosuppression, i.e administering cyclosporine for 15 days following the ischemic event. Furthermore, a concomitant reduction of reactive microglia (Iba1+ cells) and of glial, GFAP+ cells was also observed in the ipsilateral hemisphere as compared to the controlateral one. IhNSC-Ps were not tumorigenic and, upon in vivo engraftment, underwent differentiation into GFAP+ astrocytes, and β-tubulinIII+ or MAP2+ neurons, which displayed GABAergic and GLUTAmatergic markers. Electron microscopy analysis pointed to the formation of mature synaptic contacts between host and donor-derived neurons, showing the full maturation of the IhNSC-P-derived neurons and their likely functional integration into the host tissue. Thus, IhNSC-Ps possess long-term survival and engraftment capacity upon transplantation into the globally injured ischemic brain, into which they can integrate and mature into neurons, even under mild, transient immunosuppressive conditions. Most notably, transplanted IhNSC-P can significantly dampen the inflammatory response in the lesioned host brain. This work further supports hNSCs as a reliable and safe source of cells for transplantation therapy in neurodegenerative disorders.

Rescuing the neonatal brain from hypoxic injury with autologous cord blood

“…Lee et al 104 reported that the majority of the donor cells remained undifferentiated or became astroglia, with only about 5% and 4% differentiation into neurons and oligodendrocytes, respectively. In an adult ischemic brain injury model, under the condition of immunosuppression either transiently or throughout the experiment, Nodari et al 105 reported that immortal human NSCs could differentiate toward astroglial and neuronal lineage, but not oligodendrocytes in the ischemic brain. Thus, it appears that the injured brain microenvironment does not favor engraftment and regeneration of the transplanted cells.…”

Stem Cell Therapy for Amyotrophic Lateral Sclerosis

“…They possess the potential to differentiate into any cell type in the central nervous system (CNS) (although NSCs derived from adult tissues show a more limited differentiation capacity [19]). The integration ability and prospective therapeutic efficacy of human neural stem cells (hNSC) has been demonstrated in rodent models of neurological diseases [20][21][22][23]. Apart from regenerating lost neuronal cells, NSCs can also improve the functional outcomes of rats through auxiliary mechanisms, such as neurotrophism [24][25][26] and immunosuppression [27][28][29].…”

Low Immunogenic Potential of Human Neural Stem Cells

“…Interesting, functional recovery by NSC transplantation was mostly reached through alternative mechanisms rather than cell replacement (Pluchino et al 2005). These mechanisms include neuroprotection and reduction of host cell death (Chu et al 2004), enhancement of endogenous angiogenesis after stroke (Jiang et al 2005), immunomodulatory effects on inflammatory damage (Pluchino, et al 2005;Rota Nodari et al 2010;Ziv et al 2006a) and scavenging of neurotoxic molecules (Emsley et al 2004). Thus far, cells with stem-like properties have been identified in the mammalian CNS, including that of humans, throughout development and adulthood (Alvarez-Buylla et al 2001;Gage 2000;Temple 2001).…”

“…We already obtained some evidence of hNSCs efficacy and immunogenic tolerance upon transplantation into animal models of neurological disorders (Rota Nodari, et al 2010) such as transient global ischemia, which is a model of vascular dementia and resembles several pathological features of AD. At 3 days from global ischemic injury, hNSC were unilaterally implantated into the corpus callosum or the hippocampal fissure of adult rat brains.…”

“…At 3 days from global ischemic injury, hNSC were unilaterally implantated into the corpus callosum or the hippocampal fissure of adult rat brains. After 1 month, hNSCs were detected to migrate through the corpus callosum (Fig.3), into the cortex or throughout the dentate gyrus of the hippocampus and by the fourth month, to reach the ipsilateral subventricular zone, the CA1-3 hippocampal layers and the controlateral hemisphere, showing to be non-tumorigenic and to undergo a proper regional differentiation into GABAergic and GLUTAmatergic neurons (Rota Nodari, et al 2010). Notably, these results could be accomplished using transient immunosuppression, i.e administering cyclosporine for 15 days following the ischemic event.…”