RESUMO
Neural precursor cells (NPC) are an interesting tool in experimental stroke research, but their therapeutic potential is limited due to poor long-term survival. We therefore in vitro transduced subventricular zone-(SVZ)-derived NPC with the anti-apoptotic fusion protein TAT-Bcl-x(L) and analyzed NPC survival, differentiation, and post-stroke functional deficits after experimental ischemia in mice. Survival of TAT-Bcl-x(L)-transduced NPC, which were injected at day 7 post-stroke into the ischemic striatum, was significantly increased at 4 weeks after stroke. Increased survival of NPC was associated with reduced infarct injury and decreased post-stroke functional deficits. Animals grafted with TAT-Bcl-x(L)-transduced NPC showed an increased number of immature cells expressing the neuronal marker doublecortin. Since mature neuronal differentiation of NPC was not observed, reduced post-stroke injury cannot be attributed to enhanced neuronal regeneration, but rather to indirect by-stander effects of grafted NPC. In line with this, NPC-mediated neuroprotection of cortical neurons in vitro was associated with increased secretion of growth factors. Thus, in vitro transduction of cultivated NPC with TAT-Bcl-x(L) results in enhanced resistance of transplanted NPC followed by long-term neuroprotection and ameliorated functional deficits after transient focal cerebral ischemia in mice.
Assuntos
Isquemia Encefálica/genética , Isquemia Encefálica/terapia , Células-Tronco Neurais/transplante , Transplante de Células-Tronco/métodos , Acidente Vascular Cerebral/terapia , Transdução Genética/métodos , Proteína bcl-X/genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/genética , Animais , Isquemia Encefálica/metabolismo , Isquemia Encefálica/patologia , Isquemia Encefálica/cirurgia , Sobrevivência Celular/genética , Citoproteção/genética , Modelos Animais de Doenças , Técnicas de Transferência de Genes , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/patologia , Recuperação de Função Fisiológica/genética , Acidente Vascular Cerebral/genética , Acidente Vascular Cerebral/patologia , Tempo , Proteína bcl-X/uso terapêutico , Produtos do Gene tat do Vírus da Imunodeficiência Humana/uso terapêuticoRESUMO
Cerebral ischemia activates endogenous neurogenesis in the subventricular zone (SVZ) and the dentate gyrus. Consecutively, SVZ-derived neural precursors migrate towards ischemic lesions. However, functional relevance of activated neurogenesis is limited by poor survival of new-born precursors. We therefore employed the HI-virus-derived fusion protein TAT-Bcl-x(L) to study the effects of acute anti-apoptotic treatment on endogenous neurogenesis and functional outcome after transient cerebral ischemia in mice. TAT-Bcl-x(L) treatment led to significantly reduced acute ischemic cell death (128+/-23 vs. 305+/-65 TUNEL+ cells/mm(2) in controls) and infarct volumes resulting in less motor deficits and improved spatial learning. It significantly increased survival of doublecortin (Dcx)-positive neuronal precursors (389+/-96 vs. 213+/-97 Dcx+ cells in controls) but did not enhance overall post-ischemic cell proliferation or lesion-specific neuronal differentiation 28 days after ischemia. Our data demonstrate that post-stroke TAT-Bcl-x(L)-treatment results in acute neuroprotection, improved functional outcome, and enhanced survival of lesion-specific neuronal precursor cells after cerebral ischemia in mice.
