Jae-sung Bae

Intracerebral Transplantation of Bone Marrow‐Derived Mesenchymal Stem Cells Reduces Amyloid‐Beta Deposition and Rescues Memory Deficits in Alzheimer's Disease Mice by Modulation of Immune Responses

Alzheimers disease (AD) is characterized by the deposition of amyloid‐β peptide (Aβ) and the formation of neurofibrillary tangles. Transplantation of bone marrow‐derived mesenchymal stem cells (BM‐MSCs) has been suggested as a potential therapeutic approach to prevent various neurodegenerative disorders, including AD. However, the actual therapeutic impact of BM‐MSCs and their mechanism of action in AD have not yet been ascertained. The aim of this study was therefore to evaluate the therapeutic effect of BM‐MSC transplantation on the neuropathology and memory deficits in amyloid precursor protein (APP) and presenilin one (PS1) double‐transgenic mice. Here we show that intracerebral transplantation of BM‐MSCs into APP/PS1 mice significantly reduced amyloid β‐peptide (Aβ) deposition. Interestingly, these effects were associated with restoration of defective microglial function, as evidenced by increased Aβ‐degrading factors, decreased inflammatory responses, and elevation of alternatively activated microglial markers. Furthermore, APP/PS1 mice treated with BM‐MSCs had decreased tau hyperphosphorylation and improved cognitive function. In conclusion, BM‐MSCs can modulate immune/inflammatory responses in AD mice, ameliorate their pathophysiology, and improve the cognitive decline associated with Aβ deposits. These results demonstrate that BM‐MSCs are a potential new therapeutic agent for AD. STEM CELLS 2010;28:329–343

Human umbilical cord blood-derived mesenchymal stem cells improve neuropathology and cognitive impairment in an Alzheimer's disease mouse model through modulation of neuroinflammation

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSC) have a potential therapeutic role in the treatment of neurological disorders, but their current clinical usage and mechanism of action has yet to be ascertained in Alzheimers disease (AD). Here we report that hUCB-MSC transplantation into amyloid precursor protein (APP) and presenilin1 (PS1) double-transgenic mice significantly improved spatial learning and memory decline. Furthermore, amyloid-β peptide (Aβ) deposition, β-secretase 1 (BACE-1) levels, and tau hyperphosphorylation were dramatically reduced in hUCB-MSC transplanted APP/PS1 mice. Interestingly, these effects were associated with reversal of disease-associated microglial neuroinflammation, as evidenced by decreased microglia-induced proinflammatory cytokines, elevated alternatively activated microglia, and increased anti-inflammatory cytokines. These findings lead us to suggest that hUCB-MSC produced their sustained neuroprotective effect by inducing a feed-forward loop involving alternative activation of microglial neuroinflammation, thereby ameliorating disease pathophysiology and reversing the cognitive decline associated with Aβ deposition in AD mice.

Bone Marrow‐Derived Mesenchymal Stem Cells Promote Neuronal Networks with Functional Synaptic Transmission After Transplantation into Mice with Neurodegeneration

Recent studies have shown that bone marrow‐derived MSCs (BM‐MSCs) improve neurological deficits when transplanted into animal models of neurological disorders. However, the precise mechanism by which this occurs remains unknown. Herein we demonstrate that BM‐MSCs are able to promote neuronal networks with functional synaptic transmission after transplantation into Niemann‐Pick disease type C (NP‐C) mouse cerebellum. To address the mechanism by which this occurs, we used gene microarray, whole‐cell patch‐clamp recordings, and immunohistochemistry to evaluate expression of neurotransmitter receptors on Purkinje neurons in the NP‐C cerebellum. Gene microarray analysis revealed upregulation of genes involved in both excitatory and inhibitory neurotransmission encoding subunits of the ionotropic glutamate receptors (α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid, AMPA) GluR4 and GABAA receptor β2. We also demonstrated that BM‐MSCs, when originated by fusion‐like events with existing Purkinje neurons, develop into electrically active Purkinje neurons with functional synaptic formation. This study provides the first in vivo evidence that upregulation of neurotransmitter receptors may contribute to synapse formation via cell fusion‐like processes after BM‐MSC transplantation into mice with neurodegenerative disease.

Bone marrow-derived mesenchymal stem cells reduce brain amyloid-β deposition and accelerate the activation of microglia in an acutely induced Alzheimer's disease mouse model

The therapeutic potential of bone marrow-derived mesenchymal stem cells (BM-MSCs) has recently been explored in various pathological conditions of the central nervous system (CNS). However, the application of BM-MSCs in acutely induced Alzheimers disease (AD) has not yet been reported. Herein the feasibility of using the BM-MSCs, as a therapeutic agent for AD has been tested. To assess this possibility, an acutely induced AD model induced by injecting amyloid-beta (Abeta) into the dentate gyrus (DG) of hippocampus of C57BL/6 mice was used. Intracerebral transplantation of BM-MSCs into the brain of an induced AD model reduced their Abeta levels when compared to sham-transplanted animals. The diminution of Abeta deposits was accompanied by the activation of microglia. In addition, the activated microglia was located near the Abeta deposits, and their morphology was changed from ramified to ameboid as a sign of microglial phagocytosis. This study provides evidence that BM-MSCs can promote the reduction of Abeta through the microglial activation in this acutely induced AD brain, suggesting a potential therapeutic agent against AD.

The therapeutic potential of human umbilical cord blood-derived mesenchymal stem cells in Alzheimer's disease

The neuropathological hallmarks of Alzheimers disease (AD) include the presence of extracellular amyloid-beta peptide (Abeta) in the form of amyloid plaques in the brain parenchyma and neuronal loss. The mechanism associated with neuronal death by amyloid plaques is unclear but oxidative stress and glial activation has been implicated. Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) are being scrutinized as a potential therapeutic tool to prevent various neurodegenerative diseases including AD. However, the therapeutic impact of hUCB-MSCs in AD has not yet been reported. Here we undertook in vitro work to examine the potential impact of hUCB-MSCs treatment on neuronal loss using a paradigm of cultured hippocampal neurons treated with Abeta. We confirmed that hUCB-MSCs co-culture reduced the hippocampal apoptosis induced by Abeta treatment. Moreover, in an acute AD mouse model to directly test the efficacy of hUCB-MSCs treatment on AD-related cognitive and neuropathological outcomes, we demonstrated that markers of glial activation, oxidative stress and apoptosis levels were decreased in AD mouse brain. Interestingly, hUCB-MSCs treated AD mice demonstrated cognitive rescue with restoration of learning/memory function. These data suggest that hUCB-MSCs warrant further investigation as a potential therapeutic agent in AD.

Mesenchymal stem cells enhance autophagy and increase β-amyloid clearance in Alzheimer disease models

Current evidence suggests a central role for autophagy in Alzheimer disease (AD), and dysfunction in the autophagic system may lead to amyloid-β (Aβ) accumulation. Using in vitro and in vivo AD models, the present study investigated whether mesenchymal stem cells (MSCs) could enhance autophagy and thus exert a neuroprotective effect through modulation of Aβ clearance In Aβ-treated neuronal cells, MSCs increased cellular viability and enhanced LC3-II expression compared with cells treated with Aβ only. Immunofluorescence revealed that MSC coculture in Aβ-treated neuronal cells increased the number of LC3-II-positive autophagosomes that were colocalized with a lysosomal marker. Ultrastructural analysis revealed that most autophagic vacuoles (AVs) in Aβ-treated cells were not fused with lysosomes, whereas a large portion of autophagosomes were conjoined with lysosomes in MSCs cocultured with Aβ-treated neuronal cells. Furthermore, MSC coculture markedly increased Aβ immunoreactivity colocalized within lysosomes and decreased intracellular Aβ levels compared with Aβ-treated cells. In Aβ-treated animals, MSC administration significantly increased autophagosome induction, final maturation of late AVs, and fusion with lysosomes. Moreover, MSC administration significantly reduced the level of Aβ in the hippocampus, which was elevated in Aβ-treated mice, concomitant with increased survival of hippocampal neurons. Finally, MSC coculture upregulated BECN1/Beclin 1 expression in AD models. These results suggest that MSCs significantly enhance autolysosome formation and clearance of Aβ in AD models, which may lead to increased neuronal survival against Aβ toxicity. Modulation of the autophagy pathway to repair the damaged AD brain using MSCs would have a significant impact on future strategies for AD treatment.

Soluble CCL5 Derived from Bone Marrow‐Derived Mesenchymal Stem Cells and Activated by Amyloid β Ameliorates Alzheimer's Disease in Mice by Recruiting Bone Marrow‐Induced Microglia Immune Responses

Microglia have the ability to eliminate amyloid β (Aβ) by a cell‐specific phagocytic mechanism, and bone marrow (BM) stem cells have shown a beneficial effect through endogenous microglia activation in the brains of Alzheimers disease (AD) mice. However, the mechanisms underlying BM‐induced activation of microglia have not been resolved. Here we show that BM‐derived mesenchymal stem cells (MSCs) induced the migration of microglia when exposed to Aβ in vitro. Cytokine array analysis of the BM‐MSC media obtained after stimulation by Aβ further revealed elevated release of the chemoattractive factor, CCL5. We also observed that CCL5 was increased when BM‐MSCs were transplanted into the brains of Aβ‐deposited AD mice, but not normal mice. Interestingly, alternative activation of microglia in AD mice was associated with elevated CCL5 expression following intracerebral BM‐MSC transplantation. Furthermore, by generating an AD‐green fluorescent protein chimeric mouse, we ascertained that endogenous BM cells, recruited into the brain by CCL5, induced microglial activation. Additionally, we observed that neprilysin and interleukin‐4 derived from the alternative microglia were associated with a reduction in Aβ deposition and memory impairment in AD mice. These results suggest that the beneficial effects observed in AD mice after intracerebral SC transplantation may be explained by alternative microglia activation. The recruitment of the alternative microglia into the brain is driven by CCL5 secretion from the transplanted BM‐MSCs, which itself is induced by Aβ deposition in the AD brain. Stem Cells201230:1544–1555;

Acid sphingomyelinase modulates the autophagic process by controlling lysosomal biogenesis in Alzheimer’s disease

Acid sphingomyelinase activity is increased in brain and plasma of mice and patients with Alzheimer’s disease and its inhibition represents a potential new therapeutic intervention for this disease.

Human amniotic fluid stem cell injection therapy for urethral sphincter regeneration in an animal model

BackgroundStem cell injection therapies have been proposed to overcome the limited efficacy and adverse reactions of bulking agents. However, most have significant limitations, including painful procurement, requirement for anesthesia, donor site infection and a frequently low cell yield. Recently, human amniotic fluid stem cells (hAFSCs) have been proposed as an ideal cell therapy source. In this study, we investigated whether periurethral injection of hAFSCs can restore urethral sphincter competency in a mouse model.MethodsAmniotic fluids were collected and harvested cells were analyzed for stem cell characteristics and in vitro myogenic differentiation potency. Mice underwent bilateral pudendal nerve transection to generate a stress urinary incontinence (SUI) model and received either periurethral injection of hAFSCs, periurethral injection of Plasma-Lyte (control group), or underwent a sham (normal control group).For in vivo cell tracking, cells were labeled with silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate (MNPs@SiO2 (RITC)) and were injected into the urethral sphincter region (n = 9). Signals were detected by optical imaging. Leak point pressure and closing pressure were recorded serially after injection.Tumorigenicity of hAFSCs was evaluated by implanting hAFSCs into the subcapsular space of the kidney, followed two weeks later by retrieval and histologic analysis.ResultsFlow activated cell sorting showed that hAFSCs expressed mesenchymal stem cell (MSC) markers, but no hematopoietic stem cell markers. Induction of myogenic differentiation in the hAFSCs resulted in expression of PAX7 and MYOD at Day 3, and DYSTROPHIN at Day 7. The nanoparticle-labeled hAFSCs could be tracked in vivo with optical imaging for up to 10 days after injection. Four weeks after injection, the mean LPP and CP were significantly increased in the hAFSC-injected group compared with the control group. Nerve regeneration and neuromuscular junction formation of injected hAFSCs in vivo was confirmed with expression of neuronal markers and acetylcholine receptor. Injection of hAFSCs caused no in vivo host CD8 lymphocyte aggregation or tumor formation.ConclusionshAFSCs displayed MSC characteristics and could differentiate into cells of myogenic lineage. Periurethral injection of hAFSCs into an SUI animal model restored the urethral sphincter to apparently normal histology and function, in absence of immunogenicity and tumorigenicity.

Combined effects of hematopoietic progenitor cell mobilization from bone marrow by granulocyte colony stimulating factor and AMD3100 and chemotaxis into the brain using stromal cell-derived factor-1α in an Alzheimer's disease mouse model.

Transplantation of bone marrow‐derived stem cells (BMSCs) has been suggested as a potential therapeutic approach to prevent neurodegenerative diseases, but it remains problematic due to issues of engraftment, potential toxicities, and other factors. An alternative strategy is pharmacological‐induced recruitment of endogenous BMSCs into an injured site by systemic administration of growth factors or chemokines. Therefore, the aim of this study was to examine the effects of therapy involving granulocyte colony stimulating factor (G‐CSF)/AMD3100 (CXCR4 antagonist) and stromal cell‐derived factor‐1α (SDF‐1α) on endogenous BM‐derived hematopoietic progenitor cell (BM‐HPC) recruitment into the brain of an Alzheimers disease (AD) mouse model. To mobilize BM‐HPCs, G‐CSF was injected intraperitoneally and boosted by AMD3100. Simultaneously, these mice received an intracerebral injection with SDF‐1α to induce migration of mobilized BM‐HPCs into brain. We found that the memory deficit in the AD mice was significantly improved by these treatments, but amyloid β deposition was unchanged. Interestingly, microglial activation was increased with alternative activation of microglia to a neuroprotective phenotype. Furthermore, by generating an amyloid precursor protein/presenilin 1‐green fluorescent protein (GFP) chimeric mouse, we ascertained that the GFP positive microglia identified in the brain were BM‐derived. Additionally, increased hippocampal neurogenesis and improved memory was observed in mice receiving combined G‐CSF/AMD3100 and SDF‐1α, but not in controls or animals receiving each treatment alone. These results suggest that SDF‐1α is an effective adjuvant in inducing migration into brain of the endogenous BM‐HPCs, mobilized by G‐CSF/AMD3100, and that the two can act synergistically to produce a therapeutic effect. This approach warrants further investigation as a potential therapeutic option for the treatment of AD patients in the future. STEM CELLS 2011;29:1075–1089