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Human neural stem cells enhance structural plasticity and axonal transport in the ischaemic brain.

Andres RH, Horie N, Slikker W, Keren-Gill H, Zhan K, Sun G, Manley NC, Pereira MP, Sheikh LA, McMillan EL, Schaar BT, Svendsen CN, Bliss TM, Steinberg GK - Brain (2011)

Bottom Line: Our results show the first evidence that human neural progenitor cell treatment can significantly increase dendritic plasticity in both the ipsi- and contralesional cortex and this coincides with stem cell-induced functional recovery.Finally, we established in vitro co-culture assays in which these stem cells mimicked the effects observed in vivo.Through immunodepletion studies, we identified vascular endothelial growth factor, thrombospondins 1 and 2, and slit as mediators partially responsible for stem cell-induced effects on dendritic sprouting, axonal plasticity and axonal transport in vitro.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, Stanford Stroke Centre, Stanford Institute for Neuro-Innovation and Translational Neurosciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305-5487, USA.

ABSTRACT
Stem cell transplantation promises new hope for the treatment of stroke although significant questions remain about how the grafted cells elicit their effects. One hypothesis is that transplanted stem cells enhance endogenous repair mechanisms activated after cerebral ischaemia. Recognizing that bilateral reorganization of surviving circuits is associated with recovery after stroke, we investigated the ability of transplanted human neural progenitor cells to enhance this structural plasticity. Our results show the first evidence that human neural progenitor cell treatment can significantly increase dendritic plasticity in both the ipsi- and contralesional cortex and this coincides with stem cell-induced functional recovery. Moreover, stem cell-grafted rats demonstrated increased corticocortical, corticostriatal, corticothalamic and corticospinal axonal rewiring from the contralesional side; with the transcallosal and corticospinal axonal sprouting correlating with functional recovery. Furthermore, we demonstrate that axonal transport, which is critical for both proper axonal function and axonal sprouting, is inhibited by stroke and that this is rescued by the stem cell treatment, thus identifying another novel potential mechanism of action of transplanted cells. Finally, we established in vitro co-culture assays in which these stem cells mimicked the effects observed in vivo. Through immunodepletion studies, we identified vascular endothelial growth factor, thrombospondins 1 and 2, and slit as mediators partially responsible for stem cell-induced effects on dendritic sprouting, axonal plasticity and axonal transport in vitro. Thus, we postulate that human neural progenitor cells aid recovery after stroke through secretion of factors that enhance brain repair and plasticity.

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Human NPCs enhance axonal sprouting post-stroke. (A) Representative confocal images of biotinylated dextran amine (BDA) staining in the contra- and ipsilateral corpus callosum of human NPC- and vehicle-treated animals at 5 weeks post-transplantation. Scale bar = 100 µm. (B) Human NPC-grafted rats have significantly increased BDA-labelled fibre density at 3 weeks (n = 6) and 5 weeks (n = 12) post-transplantation in the cortex, corpus callosum and the ipsilesional striatum. At 5 weeks post-transplantation human NPC-grafted rats also have increased BDA signal in (C) the ipsi- and contralesional thalamus and (D) corticospinal fibres in the contralesional internal capsule and both the contra- and ipsilesional dorsal funiculus in the cervical spinal cord, C5 level. *P < 0.05 human NPC compared with vehicle at same time point. Red oval = BDA injection site; black oval = human NPC transplant site.
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Figure 3: Human NPCs enhance axonal sprouting post-stroke. (A) Representative confocal images of biotinylated dextran amine (BDA) staining in the contra- and ipsilateral corpus callosum of human NPC- and vehicle-treated animals at 5 weeks post-transplantation. Scale bar = 100 µm. (B) Human NPC-grafted rats have significantly increased BDA-labelled fibre density at 3 weeks (n = 6) and 5 weeks (n = 12) post-transplantation in the cortex, corpus callosum and the ipsilesional striatum. At 5 weeks post-transplantation human NPC-grafted rats also have increased BDA signal in (C) the ipsi- and contralesional thalamus and (D) corticospinal fibres in the contralesional internal capsule and both the contra- and ipsilesional dorsal funiculus in the cervical spinal cord, C5 level. *P < 0.05 human NPC compared with vehicle at same time point. Red oval = BDA injection site; black oval = human NPC transplant site.

Mentions: The anterograde axonal tracer biotinylated dextran amine (BDA) injected into the contralesional cortex was used to visualize axons. Human NPC-grafted rats, compared with vehicle-treated rats, appeared to increase axonal sprouting from the contralesional cortex to the ipsilesional hemisphere (Fig. 3A). This was first evident at 3 weeks post-transplantation with increased BDA-labelled fibre density in the corpus callosum and ipsilesional striatum of human NPC-treated animals (Fig. 3B). This effect was even more pronounced at 5 weeks post-transplantation with increased corticocortico, corticostriatal and corticothalamic sprouting as evidenced by significantly increased BDA-labelled fibre density in the relevant regions of interest as indicated in Fig. 3B and C. Unlike human NPC-treated animals, the vehicle-treated group showed no increase in BDA-positive fibres over time. Human NPC-grafted rats also showed enhanced corticospinal tract projections at 5 weeks post-transplantation with significantly increased BDA-labelled fibre density in the contralesional internal capsule and both the contra- and ipsilesional dorsal funiculus of the cervical spinal cord (Fig. 3D). Similar results were found when BDA was analysed by a second counting method (Supplementary material and Supplementary Fig. 2). To further substantiate human NPC-induced plasticity, we found that human NPC treatment significantly enhanced expression of the axonal growth cone protein GAP-43 in the corpus callosum and cortex of both hemispheres, with the largest increase in the ipsilesional cortex (Supplementary Fig. 1C). BDA labelling in the corpus callosum at 5 weeks post-transplantation positively correlated with functional recovery in the whisker-paw (Spearman correlation coefficient ρ = 0.802; P = 0.001) and cylinder tests (Spearman correlation coefficient ρ = 0.642; P = 0.028) when combining data from both vehicle and human NPC groups. Recovery in the whisker-paw test also positively correlated with the BDA signal in the injured corticospinal tract (Spearman correlation coefficient ρ = 0.631; P = 0.032). There was no correlation between lesion size and BDA signal. These data suggest that human NPC-induced axonal changes are important for human NPC-enhanced recovery.Figure 3


Human neural stem cells enhance structural plasticity and axonal transport in the ischaemic brain.

Andres RH, Horie N, Slikker W, Keren-Gill H, Zhan K, Sun G, Manley NC, Pereira MP, Sheikh LA, McMillan EL, Schaar BT, Svendsen CN, Bliss TM, Steinberg GK - Brain (2011)

Human NPCs enhance axonal sprouting post-stroke. (A) Representative confocal images of biotinylated dextran amine (BDA) staining in the contra- and ipsilateral corpus callosum of human NPC- and vehicle-treated animals at 5 weeks post-transplantation. Scale bar = 100 µm. (B) Human NPC-grafted rats have significantly increased BDA-labelled fibre density at 3 weeks (n = 6) and 5 weeks (n = 12) post-transplantation in the cortex, corpus callosum and the ipsilesional striatum. At 5 weeks post-transplantation human NPC-grafted rats also have increased BDA signal in (C) the ipsi- and contralesional thalamus and (D) corticospinal fibres in the contralesional internal capsule and both the contra- and ipsilesional dorsal funiculus in the cervical spinal cord, C5 level. *P < 0.05 human NPC compared with vehicle at same time point. Red oval = BDA injection site; black oval = human NPC transplant site.
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Figure 3: Human NPCs enhance axonal sprouting post-stroke. (A) Representative confocal images of biotinylated dextran amine (BDA) staining in the contra- and ipsilateral corpus callosum of human NPC- and vehicle-treated animals at 5 weeks post-transplantation. Scale bar = 100 µm. (B) Human NPC-grafted rats have significantly increased BDA-labelled fibre density at 3 weeks (n = 6) and 5 weeks (n = 12) post-transplantation in the cortex, corpus callosum and the ipsilesional striatum. At 5 weeks post-transplantation human NPC-grafted rats also have increased BDA signal in (C) the ipsi- and contralesional thalamus and (D) corticospinal fibres in the contralesional internal capsule and both the contra- and ipsilesional dorsal funiculus in the cervical spinal cord, C5 level. *P < 0.05 human NPC compared with vehicle at same time point. Red oval = BDA injection site; black oval = human NPC transplant site.
Mentions: The anterograde axonal tracer biotinylated dextran amine (BDA) injected into the contralesional cortex was used to visualize axons. Human NPC-grafted rats, compared with vehicle-treated rats, appeared to increase axonal sprouting from the contralesional cortex to the ipsilesional hemisphere (Fig. 3A). This was first evident at 3 weeks post-transplantation with increased BDA-labelled fibre density in the corpus callosum and ipsilesional striatum of human NPC-treated animals (Fig. 3B). This effect was even more pronounced at 5 weeks post-transplantation with increased corticocortico, corticostriatal and corticothalamic sprouting as evidenced by significantly increased BDA-labelled fibre density in the relevant regions of interest as indicated in Fig. 3B and C. Unlike human NPC-treated animals, the vehicle-treated group showed no increase in BDA-positive fibres over time. Human NPC-grafted rats also showed enhanced corticospinal tract projections at 5 weeks post-transplantation with significantly increased BDA-labelled fibre density in the contralesional internal capsule and both the contra- and ipsilesional dorsal funiculus of the cervical spinal cord (Fig. 3D). Similar results were found when BDA was analysed by a second counting method (Supplementary material and Supplementary Fig. 2). To further substantiate human NPC-induced plasticity, we found that human NPC treatment significantly enhanced expression of the axonal growth cone protein GAP-43 in the corpus callosum and cortex of both hemispheres, with the largest increase in the ipsilesional cortex (Supplementary Fig. 1C). BDA labelling in the corpus callosum at 5 weeks post-transplantation positively correlated with functional recovery in the whisker-paw (Spearman correlation coefficient ρ = 0.802; P = 0.001) and cylinder tests (Spearman correlation coefficient ρ = 0.642; P = 0.028) when combining data from both vehicle and human NPC groups. Recovery in the whisker-paw test also positively correlated with the BDA signal in the injured corticospinal tract (Spearman correlation coefficient ρ = 0.631; P = 0.032). There was no correlation between lesion size and BDA signal. These data suggest that human NPC-induced axonal changes are important for human NPC-enhanced recovery.Figure 3

Bottom Line: Our results show the first evidence that human neural progenitor cell treatment can significantly increase dendritic plasticity in both the ipsi- and contralesional cortex and this coincides with stem cell-induced functional recovery.Finally, we established in vitro co-culture assays in which these stem cells mimicked the effects observed in vivo.Through immunodepletion studies, we identified vascular endothelial growth factor, thrombospondins 1 and 2, and slit as mediators partially responsible for stem cell-induced effects on dendritic sprouting, axonal plasticity and axonal transport in vitro.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, Stanford Stroke Centre, Stanford Institute for Neuro-Innovation and Translational Neurosciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305-5487, USA.

ABSTRACT
Stem cell transplantation promises new hope for the treatment of stroke although significant questions remain about how the grafted cells elicit their effects. One hypothesis is that transplanted stem cells enhance endogenous repair mechanisms activated after cerebral ischaemia. Recognizing that bilateral reorganization of surviving circuits is associated with recovery after stroke, we investigated the ability of transplanted human neural progenitor cells to enhance this structural plasticity. Our results show the first evidence that human neural progenitor cell treatment can significantly increase dendritic plasticity in both the ipsi- and contralesional cortex and this coincides with stem cell-induced functional recovery. Moreover, stem cell-grafted rats demonstrated increased corticocortical, corticostriatal, corticothalamic and corticospinal axonal rewiring from the contralesional side; with the transcallosal and corticospinal axonal sprouting correlating with functional recovery. Furthermore, we demonstrate that axonal transport, which is critical for both proper axonal function and axonal sprouting, is inhibited by stroke and that this is rescued by the stem cell treatment, thus identifying another novel potential mechanism of action of transplanted cells. Finally, we established in vitro co-culture assays in which these stem cells mimicked the effects observed in vivo. Through immunodepletion studies, we identified vascular endothelial growth factor, thrombospondins 1 and 2, and slit as mediators partially responsible for stem cell-induced effects on dendritic sprouting, axonal plasticity and axonal transport in vitro. Thus, we postulate that human neural progenitor cells aid recovery after stroke through secretion of factors that enhance brain repair and plasticity.

Show MeSH
Related in: MedlinePlus