GM-CSF enhances neural differentiation of bone marrow stromal cells

Neural Basis of Dental Pulp Stem Cells and its Potential Application in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease. Though significant insights into the molecular-biochemical-cellular-behavioral basis of PD have been understood, there is no appreciable treatment available till date. Current therapies provide symptomatic relief without any influence on the progression of the disease. Stem cell therapy has been vigorously explored to treat PD. In this comprehensive review, we analyze various stem cell candidates for treating PD and discuss the possible mechanisms. We advocate the advantage of using neural crest originated dental pulp stem cells (DPSC) due to their predisposition towards neural differentiation and their potential to regenerate neurons far better than commonly used bone marrow derived mesenchymal stem cells (BM-MSCs). Eventually, we highlight the current challenges in the field and the strategies which may be used for overcoming the impediments.

Effects of degradable magnesium on paracrine signaling between human umbilical cord perivascular cells and peripheral blood mononuclear cells

Human mesenchymal stem cells (MSC) interact with numerous immune cells that can promote regenerative processes and inhibit inflammatory responses. We hypothesised that the cross-talk between human umbilical cord perivascular cells (HUCPV; an alternative source of MSC) and peripheral blood mononuclear cells (PBMC) could be influenced by degradable transwell magnesium (Mg). To study the correlations between paracrine signaling and specific cellular behaviour during the host response to Mg, we used a transwell coculture system for up to 7 days. The proliferation and viability of both cell types were not significantly influenced by Mg. When HUCPV were cultured with degradable Mg, a moderate inflammation (e.g., lower secretions of pro-inflammatory interleukin 1 beta and IL2, and tumour necrosis factor alpha, interferon gamma, anti-inflammatory interleukins 4, 5, 10, 13, and 1 receptor antagonists and granulocyte colony stimulating factor), and an increased pro-healing M2 macrophage phenotype were observed. Moreover, when PBMC were cultured with degradable Mg, the expression of migration/wound healing related cytokines (interleukin 8, granulocyte-macrophage colony-stimulating factor, monocyte chemoattractant protein 1 and macrophage inflammatory protein 1α/β) was upregulated, accompanied by an increase in the migration ability of HUCPV (cell scratch assay). In addition, an increased pro-osteogenic potential was demonstrated via an increase of osteoblastic markers (e.g., alkaline phosphatase activity, specific gene expression and cytokine release). These results collectively imply that Mg possesses osteo-immunomodulatory properties. They also help to design Mg-based bone substitute biomaterials capable of exhibiting desired immune reactions and good clinical performance.

Granulocyte macrophage colony-stimulating factor shows anti-apoptotic activity via the PI3K-NF-κB-HIF-1α-survivin pathway in mouse neural progenitor cells

Granulocyte macrophage-colony stimulating factor (GM-CSF) is a hematopoietic cytokine that plays a crucial role in regulating the proliferation, differentiation, and survival of hematopoietic cells. Recent studies have shown that GM-CSF also has anti-apoptotic effects and regulates the expression of anti-apoptotic genes including Bcl-2 family proteins in neuronal cells in vitro and in vivo. However, the mechanism underlying the anti-apoptotic function of GM-CSF is not well understood. In the present work, we examined the role of phosphoinositide 3-kinase (PI3K)-AKT signal pathway in the anti-apoptotic activity of GM-CSF in mouse neural progenitor cells (NPCs). In terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, the anti-apoptotic effect of GM-CSF (apoptotic population of approximately 8.17 %) on staurosporine-induced apoptosis of NPCs (31.09 %) was significantly blocked by LY294002, an inhibitor of PI3K signal (24.04 %). We found that the PI3K-AKT signal pathway induced by GM-CSF treatment activated nuclear factor κB (NF-κB) and increased the expression of hypoxia-inducible factor 1α (HIF-1α) in normoxic conditions. Analyses using specific small interfering RNAs (siRNAs) showed that NF-κB was an upstream molecule of HIF-1α and activated its expression at the mRNA level. Further analyses using the siRNAs and chromatin immunoprecipitation (ChIP) showed that HIF-1α was responsible for the induced expression of survivin, a member of the inhibitor of apoptosis proteins (IAPs). Each of the specific siRNAs for NF-κB, HIF-1α, and survivin inhibited significantly the anti-apoptotic activity of GM-CSF on the staurosporine-induced apoptosis in NPCs in TUNEL assays. The results of this study showed the downstream signals and mechanism of PI3K/AKT-mediated anti-apoptotic activity of GM-CSF in NPCs, particularly revealing the role of the NF-κB-HIF-1α-survivin cascade.

Concise review: adult mesenchymal stem cells, adult neural crest stem cells, and therapy of neurological pathologies: a state of play

Adult stem cells are endowed with in vitro multilineage differentiation abilities and constitute an attractive autologous source of material for cell therapy in neurological disorders. With regard to lately published results, the ability of adult mesenchymal stem cells (MSCs) and neural crest stem cells (NCSCs) to integrate and differentiate into neurons once inside the central nervous system (CNS) is currently questioned. For this review, we collected exhaustive data on MSC/NCSC neural differentiation in vitro. We then analyzed preclinical cell therapy experiments in different models for neurological diseases and concluded that neural differentiation is probably not the leading property of adult MSCs and NCSCs concerning neurological pathology management. A fine analysis of the molecules that are secreted by MSCs and NCSCs would definitely be of significant interest regarding their important contribution to the clinical and pathological recovery after CNS lesions.

Memantine combined with environmental enrichment improves spatial memory and alleviates Alzheimer's disease-like pathology in senescence-accelerated prone-8 (SAMP8) mice

Memantine is a N-methyl-D-aspartate (NMDA) receptor antagonist approved for the treatment of moderate to severe Alzheimer's disease (AD). Environmental enrichment (EE) has shown significant beneficial effects on functional improvement in AD. In this study, we sought to determine whether combining these two distinct therapies would yield greater benefit than either drug used alone. We investigated the effect of memantine combined with EE on spatial learning and memory and AD-like pathology in a widely used AD model, the senescence-accelerated prone mice (SAMP8). The SAMP8 mice were randomly assigned to enriched housing (EH) or standard housing (SH), where either memantine (20 mg/kg) or saline was given by gastric lavage once daily continuously for eight weeks. Our results showed that, when provided separately, memantine and EE significantly improved spatial learning and memory by shortening escape latencies and increasing the frequency of entrance into the target quadrant. When combined, memantine and EE showed additive effect on learning and memory as evidenced by significant shorter escape latencies and higher frequency of target entrance than either drug alone. Consistent with the behavior results, pathological studies showed that both memantine and EE significantly reduced hippocampal CA1 neurofibrilliary tangles (NFTs) as well as amyloid beta precursor protein (APP) levels. Combining both therapies synergistically lessened NFTs and APP expression compared to either drug alone in SAMP8 mice, indicating that the combination of memantine with EE could offer a novel and efficient therapeutic strategy for the treatment of AD.

Granulocyte-macrophage colony-stimulating factor-transfected bone marrow stromal cells for the treatment of ischemic stroke

Adult, male, Sprague-Dawley rats were injected with granulocyte-macrophage colony-stimulating factor-transfected bone marrow stromal cells (GM-CSF-BMSCs) into the ischemic boundary zone at 24 hours after onset of middle cerebral artery occlusion. Results showed reduced infarct volume, decreased number of apoptotic cells, improved neurological functions, increased angiogenic factor expression, and increased vascular density in the ischemic boundary zone in rats that underwent GM-CSF-BMSCs transplantation compared with the BMSCs group. Experimental findings suggested that GM-CSF-BMSCs could serve as a potential therapeutic strategy for ischemic stroke and are superior to BMSCs alone.

Granulocyte macrophage-colony stimulating factor shows anti-apoptotic activity in neural progenitor cells via JAK/STAT5-Bcl-2 pathway

Recently, many studies have shown that granulocyte macrophage-colony stimulating factor (GM-CSF) has anti-apoptotic activity and regulates the expression of anti-apoptotic genes including Bcl-2 family proteins in neuronal cells in vitro and in vivo. This study investigated detailed mechanism of GM-CSF involved in its anti-apoptotic activity and regulation of Bcl-2 expression in neural progenitor cells (NPCs) as a model. NPCs were cultured from the brain of E13 ICR mouse. When NPCs were treated with staurosporine at 1 μM, apoptosis occurred in more than 30% of cells in TUNEL assay. However, apoptosis was significantly inhibited by pre-treatment with GM-CSF at 10 ng/ml. Under the same experimental condition, the expression of both Bcl-2 and Bcl-xl was clearly induced by GM-CSF regardless of staurosporine treatment in RT-PCR and Western blot analyses. GM-CSF was shown to induce the expression of Bcl-2 and Bcl-xl via Janus tyrosine kinase (JAK) but not via phosphatidylinositol 3-kinase (PI3K) or RAS-mitogen activated protein kinase kinase-1 (MEK-1) using specific signal pathway inhibitors. Further analyses showed that the expression of Bcl-2 and Bcl-xl was induced by GM-CSF via signal transducers and activators of transcription 5 (STAT5) and STAT3, respectively. In addition, JAK/STAT5-Bcl-2 pathway but not JAK/STAT3-Bcl-xl pathway was responsible for the anti-apoptotic activity of GM-CSF in NPCs in TUNEL assay. To our knowledge, this study is the first report that shows differential roles of Bcl-2 and Bcl-xl, and their regulation mechanism involved in the anti-apoptotic activity of GM-CSF in NPCs.

Dynamic changes of cell cycle elements in the ischemic brain after bone marrow stromal cells transplantation in rats

Transplantation of bone marrow stromal cells (BMSCs) improves animal neurological functional recovery after stroke. But the mechanism remains unclear. As cell cycle machinery plays an important role in stroke, we investigated the dynamic changes of cell cycle elements in a rat model of middle cerebral artery occlusion. We found the cell cycle markers, cdk4 along with its activator cyclin D1, and proliferating cell nuclear antigen (PCNA), increased after brain ischemia-reperfusion. Phosphorylation of the retinoblastoma protein (pRb, on ser-795), the cyclin D/cdk4 complex mutual target, was upregulated accordingly. However, intravenously administrated BMSCs facilitated cyclin D1, cdk4, and PCNA decrease in the ischemic cortex. Meanwhile, phospho-pRb (ser-795) was completely inhibited. On the contrary, endogenous cdk inhibitor p27 reduced before but enhanced after BMSCs treatment. These findings suggested BMSCs might modulate cell cycle progression in injured brain via downregulation of the cyclin D1/cdk4/pRb pathway as well as upregulation of p27 level. These results provide another way by which BMSCs may contribute to the recovery from stroke.