Intracerebral Transplantation of BDNF-overexpressing Human Neural Stem Cells (HB1.F3.BDNF) Promotes Migration, Differentiation and Functional Recovery in a Rodent Model of Huntington’s Disease

Huntington’s disease (HD) is a dominantly inherited neurodegenerative disorder caused by abnormally expanded CAG repeats in the huntingtin gene. The huntingtin gene mutation leads to the progressive degeneration of striatal GABAergic medium spiny neurons (MSN) and reduces the level of brain-derived neurotrophic factor (BDNF) in HD patient’s brain. BDNF is an essential neurotrophic factor for the cortico-striatal synaptic activity and the survival of GABAergic neurons. In this study, we transplanted BDNF-overexpressing human neural stem cells (HB1.F3.BDNF) into the contra-lateral side of unilateral quinolinic acid (QA)-lesioned striatum of HD rat model. The results of in vivo transplantation were monitored using various behavioral tests, 4.7 T animal magnetic resonance imaging (MRI) and immunohistochemical staining. We observed that the QA-lesioned rats receiving HB1.F3.BDNF cells exhibited significant behavioral improvements in the stepping, rotarod and apomorphine-induced rotation tests. Interestingly, contralaterally transplanted cells were migrated to the QA-lesioned striatum and the size of lateral ventricle was reduced. Histological analyses further revealed that the transplanted cells, which had migrated to the QA lesion site, were differentiated into the cells of GABAergic, MSN-type neurons expressing DARPP-32, and neural networks were established between the transplanted cells and the host brain, as revealed by retrograde tracing. Finally, there was a significant reduction of inflammatory response in HB1.F3.BDNF-transplanted HD animal model, compared with vehicle-transplanted group. Taken together, these results suggest that HB1.F3.BDNF can be an effective therapeutic strategy to treat HD patients in the future.

In Vivo Roles of a Patient-Derived Induced Pluripotent Stem Cell Line (HD72-iPSC) in the YAC128 Model of Huntington's Disease

Induced pluripotent stem cells (iPSCs) generated from somatic cells of patients can provide immense opportunities to model human diseases, which may lead to develop novel therapeutics. Huntington's disease (HD) is a devastating neurodegenerative genetic disease, with no available therapeutic options at the moment. We recently reported the characteristics of a HD patient-derived iPSC carrying 72 CAG repeats (HD72-iPSC). In this study, we investigated the in vivo roles of HD72-iPSC in the YAC128 transgenic mice, a commonly used HD mouse model carrying 128 CAG repeats. To do this, we transplanted HD72-iPSC-derived neural precursors into the striatum of YAC128 mice bilaterally and observed a significant behavioral improvement in the grafted mice. Interestingly, the transplanted HD72-iPSC-derived neural precursors formed GABAeric neurons efficiently, but no EM48-positive protein aggregates were detected at 12 weeks after transplantation. Taken together, these results indicate no HD pathology was developed from the grafted cells, or no transmission of HD pathology from the host to the graft occurred at 12 weeks post-transplantation.

Contralaterally transplanted human embryonic stem cell-derived neural precursor cells (ENStem-A) migrate and improve brain functions in stroke-damaged rats

The transplantation of neural precursor cells (NPCs) is known to be a promising approach to ameliorating behavioral deficits after stroke in a rodent model of middle cerebral artery occlusion (MCAo). Previous studies have shown that transplanted NPCs migrate toward the infarct region, survive and differentiate into mature neurons to some extent. However, the spatiotemporal dynamics of NPC migration following transplantation into stroke animals have yet to be elucidated. In this study, we investigated the fates of human embryonic stem cell (hESC)-derived NPCs (ENStem-A) for 8 weeks following transplantation into the side contralateral to the infarct region using 7.0T animal magnetic resonance imaging (MRI). T2- and T2*-weighted MRI analyses indicated that the migrating cells were clearly detectable at the infarct boundary zone by 1 week, and the intensity of the MRI signals robustly increased within 4 weeks after transplantation. Afterwards, the signals were slightly increased or unchanged. At 8 weeks, we performed Prussian blue staining and immunohistochemical staining using human-specific markers, and found that high percentages of transplanted cells migrated to the infarct boundary. Most of these cells were CXCR4-positive. We also observed that the migrating cells expressed markers for various stages of neural differentiation, including Nestin, Tuj1, NeuN, TH, DARPP-32 and SV38, indicating that the transplanted cells may partially contribute to the reconstruction of the damaged neural tissues after stroke. Interestingly, we found that the extent of gliosis (glial fibrillary acidic protein-positive cells) and apoptosis (TUNEL-positive cells) were significantly decreased in the cell-transplanted group, suggesting that hESC-NPCs have a positive role in reducing glia scar formation and cell death after stroke. No tumors formed in our study. We also performed various behavioral tests, including rotarod, stepping and modified neurological severity score tests, and found that the transplanted animals exhibited significant improvements in sensorimotor functions during the 8 weeks after transplantation. Taken together, these results strongly suggest that hESC-NPCs have the capacity to migrate to the infarct region, form neural tissues efficiently and contribute to behavioral recovery in a rodent model of ischemic stroke.

In vivo Tracking of Human Neural Stem Cells Following Transplantation into a Rodent Model of Ischemic Stroke

BACKGROUND AND OBJECTIVES: Ischemic stroke caused by middle cerebral artery occlusion (MCAo) is the major type of stroke, but there are currently very limited options for cure. It has been shown that neural stem cells (NSCs) or neural precursor cells (NPCs) can survive and improve neurological deficits when they are engrafted in animal models of various neurological diseases. However, how the transplanted NSCs or NPCs are act in vivo in the injured or diseased brain is largely unknown. In this study, we utilized magnetic resonance imaging (MRI) techniques in order to understand the fates of human NSCs (HB1.F3) following transplantation into a rodent model of MCAo. METHODS AND RESULTS: HB1.F3 human NSCs were pre-labeled with ferumoxides (Feridex(R))-protamine sulfate complexes, which were visualized and examined by MRI up to 9 weeks after transplantation. Migration of the transplanted cells to the infarct area was further confirmed by histological methods. CONCLUSIONS: Based on these observations, we speculate that the transplanted NSCs have the extensive migratory ability to the injured site, which will in turn contribute to functional recovery in stroke.

Neuronal Differentiation of a Human Induced Pluripotent Stem Cell Line (FS-1) Derived from Newborn Foreskin Fibroblasts

Isolation of induced pluripotent stem cells (iPSCs) from fully differentiated somatic cells has revolutionized existing concepts of cell differentiation and stem cells. Importantly, iPSCs generated from somatic cells of patients can be used to model different types of human diseases. They may also serve as autologous cell sources that can be used in transplantation therapy. In this study, we investigated the neuronal properties of an iPSC line that is derived from human neonatal foreskin fibroblasts (FS-1). We initially examined the morphology and marker expression of FS-1 cells at undifferentiated stage. We then spontaneously differentiated FS-1 cells in suspension culture and examined the expression of markers representing three germ layers. We finally differentiated FS-1 cells into neuronal lineages by co-culturing them with PA6 stromal cells, and found that, under the conditions we used, they have a tendency to differentiate into more forebrain-type neurons, suggesting that FS-1 iPSC-derived neural cells will be useful to be used in cell therapy of stroke or Huntington's disease, among others. Taken together, FS-1 cells derived from human neonatal fibroblasts exhibit very similar properties with human ES cells, and can provide useful sources for cell therapy and various other applications.