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Induced pluripotent stem cells (iPSCs) or their progeny, derived from human somatic cells, can give rise to functional improvements after intracerebral transplantation in animal models of stroke. Previous studies have indicated that reactive gliosis, which is associated with stroke, inhibits neurogenesis from both endogenous and grafted neural stem/progenitor cells (NSPCs) of rodent origin. Here we have assessed whether reactive astrocytes affect the fate of human iPSC-derived NSPCs transplanted into stroke-injured brain. Mice with genetically attenuated reactive gliosis (deficient for GFAP and vimentin) were subjected to cortical stroke and cells were implanted adjacent to the ischemic lesion one week later. At 8 weeks after transplantation, immunohistochemical analysis showed that attenuated reactive gliosis did not affect neurogenesis or commitment towards glial lineage of the grafted NSPCs. Our findings, obtained in a human-to-mouse xenograft experiment, provide evidence that the reactive gliosis in stroke-injured brain does not affect the formation of new neurons from intracortically grafted human iPSC-derived NSPCs. However, for a potential clinical translation of these cells in stroke, it will be important to clarify whether the lack of effect of reactive gliosis on neurogenesis is observed also in a human-to-human experimental setting. [ABSTRACT FROM AUTHOR]

Apoptosis is an active process that plays a key role in many physiological and pathological conditions. One of the most important organelles involved in apoptosis regulation is the mitochondrion. An increase in intracellular Ca2+ is a general mechanism of toxicity in neurons which occurs in response to different noxious stimuli like excitotoxicity and ischemia producing apoptotic and necrotic cell death through mitochondria-dependent mechanisms. The Bcl-2 family of proteins modulate the release of pro-apoptotic factors from the mitochondrial intermembrane space during cell death induction by different stimuli. In this work, we have studied, using single-cell imaging and patch-clamp single channel recording, the mitochondrial mechanisms involved in the neuroprotective effect of Bcl-xL on Ca2+overload-mediated cell death in human neuroblastoma SH-SY5Y cells. We have found that Bcl-xL neuroprotective actions take place at mitochondria where this antiapoptotic protein delays both mitochondrial potential collapse and opening of the permeability transition pore by preventing Ca2+-mediated mitochondrial multiple conductance channel opening. Bcl-xL neuroprotective actions were antagonized by the Bcl-xL inhibitor ABT-737 and potentiated by the Ca2+ chelator BAPTA-AM. As a consequence, this would prevent free radical production, mitochondrial membrane permeabilization, release from mitochondria of pro-apoptotic molecules, caspase activation and cellular death. [ABSTRACT FROM AUTHOR]

Apoptosis is an active process that plays a key role in many physiological and pathological conditions. One of the most important organelles involved in apoptosis regulation is the mitochondrion. An increase in intracellular Ca(2+) is a general mechanism of toxicity in neurons which occurs in response to different noxious stimuli like excitotoxicity and ischemia producing apoptotic and necrotic cell death through mitochondria-dependent mechanisms. The Bcl-2 family of proteins modulate the release of pro-apoptotic factors from the mitochondrial intermembrane space during cell death induction by different stimuli. In this work, we have studied, using single-cell imaging and patch-clamp single channel recording, the mitochondrial mechanisms involved in the neuroprotective effect of Bcl-x(L) on Ca(2+) overload-mediated cell death in human neuroblastoma SH-SY5Y cells. We have found that Bcl-x(L) neuroprotective actions take place at mitochondria where this antiapoptotic protein delays both mitochondrial potential collapse and opening of the permeability transition pore by preventing Ca(2+)-mediated mitochondrial multiple conductance channel opening. Bcl-x(L) neuroprotective actions were antagonized by the Bcl-x(L) inhibitor ABT-737 and potentiated by the Ca(2+) chelator BAPTA-AM. As a consequence, this would prevent free radical production, mitochondrial membrane permeabilization, release from mitochondria of pro-apoptotic molecules, caspase activation and cellular death.