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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 451 records · Page 25

Copine1 regulates neural stem cell functions during brain development

Highlights: • Copine1 is highly expressed in neural lineage cells at early developmental stages. • Copine1 regulates the proliferation of embryonic neural stem cells (NSCs). • Copine1 regulates the differentiation of NSCs into neuronal and glial lineages. • mTOR signaling pathway is involved in Copine1-meidated neural development. Copine 1 (CPNE1) is a well-known phospholipid binding protein in plasma membrane of various cell types. In brain cells, CPNE1 is closely associated with AKT signaling pathway, which is important for neural stem cell (NSC) functions during brain development. Here, we investigated the role of CPNE1 in the regulation of brain NSC functions during brain development and determined its underlying mechanism. In this study, abundant expression of CPNE1 was observed in neural lineage cells including NSCs and immature neurons in human. With mouse brain tissues in various developmental stages, we found that CPNE1 expression was higher at early embryonic stages compared to postnatal and adult stages. To model developing brain in vitro, we used primary NSCs derived from mouse embryonic hippocampus. Our in vitro study shows decreased proliferation and multi-lineage differentiation potential in CPNE1 deficient NSCs. Finally, we found that the deficiency of CPNE1 downregulated mTOR signaling in embryonic NSCs. These data demonstrate that CPNE1 plays a key role in the regulation of NSC functions through the activation of AKT-mTOR signaling pathway during brain development.

60 APPLIED LIFE SCIENCES↗

W9 peptide enhanced osteogenic differentiation of human adipose-derived stem cells

W9 is a peptide that abrogates osteoclast differentiation via blockade of nuclear factor-κB ligand (RANKL)-RANK signaling, which activates bone formation. However, W9 stimulated osteogenesis in osteoblasts and mesenchymal stem cells. The present study demonstrated that the W9 peptide promoted osteogenic differentiation of human adipose-derived stem cells (hAdSCs) even under non-osteogenic differentiation culture conditions. W9-treated hAdSCs exhibited several osteocalcin-expressing cells and great mineralization compared to the BMP2-treated hAdSCs, which suggests that the W9 peptide had potent osteogenic potential in hAdSCs. W9 treatment also markedly enhanced the phosphorylation of p38, JNK, Erk1/2, and Akt, and BMP2 treatment only enhanced the phosphorylation of p38 and Erk1/2 in hAdSCs. hAdSCs did not express the RANKL gene, but W9 treatment upregulated Runx2, Collagen type 1A1 and TGF receptor genes and increased Akt phosphorylation. These results suggest that the W9-induced potent osteogenic induction was attributed to activation of TGF and the PI3 kinase/Akt signaling pathway in hAdSCs.

60 APPLIED LIFE SCIENCES↗

UNC-5 netrin receptor B mediates osteogenic differentiation by modulating bone morphogenetic protein signaling in human adipose-derived stem cells

Highlights: • UNC5B facilitates osteogenic differentiation of human adipose-derived stem cells. • It does so by modulation bone morphogenetic protein signaling. • UNC5B may be useful for bone tissue engineering and therapy for bone defects. UNC-5 netrin receptor B (UNC5B) is a dependence receptor of netrin-1 that plays an essential role in mediating angiogenesis and tumorigenesis. Despite its significant roles, there is limited knowledge about the role played by UNC5B in osteogenesis. In the present study, we first demonstrated that UNC5B was required for osteogenic differentiation of human adipose-derived stem cells (hASCs), both in vitro and in vivo. We also found that mechanistically, UNC5B promotes osteogenic differentiation by activating bone morphogenetic protein signaling. These findings point to a new important function of UNC5B and provide a potential basis for hASCs-mediated bone regeneration.

60 APPLIED LIFE SCIENCES↗

Generation of branching ureteric bud tissues from human pluripotent stem cells

Highlights: • Anterior intermediate mesoderm differentiates from anterior primitive streak. • An efficient 2D differentiation method for Wolffian duct (WD) cells was established. • A simplified method to form 3D WD epithelial structures was developed. • Branching ureteric bud tissues can be generated from human pluripotent stem cells. Recent progress in kidney regeneration research is noteworthy. However, the selective and robust differentiation of the ureteric bud (UB), an embryonic renal progenitor, from human pluripotent stem cells (hPSCs) remains to be established. The present study aimed to establish a robust induction method for branching UB tissue from hPSCs towards the creation of renal disease models. Here, we found that anterior intermediate mesoderm (IM) differentiates from anterior primitive streak, which allowed us to successfully develop an efficient two-dimensional differentiation method of hPSCs into Wolffian duct (WD) cells. We also established a simplified procedure to generate three-dimensional WD epithelial structures that can form branching UB tissues. This system may contribute to hPSC-based regenerative therapies and disease models for intractable disorders arising in the kidney and lower urinary tract.

60 APPLIED LIFE SCIENCES↗

Generation of three-dimensional retinal organoids expressing rhodopsin and S- and M-cone opsins from mouse stem cells

Highlights: • Modified SFEBq culture enabled the visualization of each photoreceptor subtype. • 9-cis retinoic acid (9cRA) promoted rod photoreceptor development in the 3D retina. • 3D retinas could be maintained for a longer period by 1% FBS supplementation. Three-dimensional retinal organoids can be differentiated from embryonic stem cells/induced pluripotent stem cells (ES/iPS cells) under defined medium conditions. We modified the serum-free floating culture of embryoid body-like aggregates with quick reaggregation (SFEBq) culture procedure to obtain retinal organoids expressing more rod photoreceptors and S- and M-cone opsins.

60 APPLIED LIFE SCIENCES↗

CBFA2T2 is required for BMP-2-induced osteogenic differentiation of mesenchymal stem cells

Highlights: • CBFA2T2 expression was upregulated by BMP-2 treatment during osteogenesis of MSCs. • Knockdown of CBFA2T2 blunted the BMP-2-induced osteogenic differentiation of MSCs. • Knockdown of CBFA2T2 promoted expression of EHMT1 in BMP-2-treated mBMSCs. • Knockdown of CBFA2T2 increased H3K9me2 levels at promoter of Runx2. Bone morphogenetic protein (BMP) signaling is one of the essential pathways involved in osteogenic differentiation of mesenchymal stem cells (MSCs) and regulation of bone formation. While BMP-2 has been approved for clinic use, the underlying mechanisms remain not fully understood. In this study, we found co-repressor CBFA2T2 (core-binding factor, runt domain, alpha subunit 2, translocated to, 2) expression was significantly upregulated in response to BMP-2 treatment during osteogenic differentiation of human dental pulp stem cells (hDPSCs) and mouse bone marrow stromal cells (mBMSCs). siRNA-mediated knockdown of CBFA2T2 blunted the BMP-2-induced allkaline phosphatase (ALP) activity, mineralization of extracelluar matrix (ECM), and expression of osteogenic related genes in both hDPSCs and mBMSCs. Mechanistically, knockdown of CBFA2T2 promoted expression of euchromatic histone methyltransferase 1 (EHMT1) in mBMSCs, which further led to upregulation of H3K9me2 levels at promoter of runt related transcription factor 2 (Runx2), the master regulator of osteogenesis. Collectively, our findings indicate that CBFA2T2 is required for BMP-2-induced osteogenic differentiation of MSCs through inhibition of EHMT1-mediated histone methylation at Runx2 promoter.

60 APPLIED LIFE SCIENCES↗

Knockdown of ARL4C inhibits osteogenic differentiation of human adipose-derived stem cells through disruption of the Wnt signaling pathway

Highlights: • Osteogenic differentiation of human adipose-derived stem cells was studied. • ARL4C is a regulator of osteogenic differentiation in vitro and in vivo. • ARL4C knockdown downregulates Wnt non-canonical pathway components. • Wnt canonical pathway protein LRP6 is downregulated in ARL4C knockdown cells. ADP-ribosylation factor-like 4C (ARL4C) has been shown to play an important role in cholesterol secretion, microtubule dynamics, and cell morphological changes. However, its role in osteogenesis has not been explored. In this study, we found that ARL4C is downregulated during the osteogenic differentiation of human adipose derived stem cells (hASCs). Knockdown of ARL4C suppresses osteogenesis of hASCs in vitro and in vivo. We demonstrate that ARL4C knockdown likely attenuates osteogenesis of hASCs through inhibition of the Wnt signaling pathway. These results provide new insights into the mechanisms of osteogenic differentiation and provide a potential molecular target for bone tissue engineering.

60 APPLIED LIFE SCIENCES↗

Next-generation sequencing-based miRNA expression analysis in Parp1-deficient embryonic stem cell-derived exosomes

Highlights: • This is the first report for the extracellular role of Parp1 via exosomal miRNAs. • Parp1{sup −/−} embryonic stem cell-derived exosomes were examined for miRNA regulation. • Next-generation sequencing revealed upregulated and downregulated miRNAs. • Upregulated miRNAs were associated with five signaling pathways. • Gene ontology annotation for growth/stress-related signaling and cell communication. Poly (ADP-ribose) polymerase family, member 1 (Parp1) has pleiotropic and disparate functions in multiple cellular signaling pathways through post-translational protein modification. It contributes to the regulation of various cellular processes, including DNA damage repair, cell death, and cell differentiation, genetically or epigenetically. Meanwhile, the functions of Parp1 in intercellular signaling remain to be established. To examine the functions of Parp1 in intercellular signaling, we examined microRNA (miRNA) regulation in exosomes derived from Parp1-deficient (Parp1{sup −/−}) embryonic stem (ES) cells. The percentages of miRNAs among total RNAs, including small RNAs such as miRNAs, snRNAs, snoRNAs, tRNAs, exonic RNAs, and intronic RNAs, in Parp1{sup +/+} and Parp1{sup −/−} ES cell-derived exosomes were 8.2% and 3.5%, respectively. Overall, 329 distinct miRNAs exhibited ≥2-fold changes (118 upregulated; 211 downregulated). The upregulated miRNAs targeted 810 candidate genes, and the downregulated miRNAs targeted 716 candidate genes. Pathway analyses revealed that the upregulated miRNAs were significantly associated with five pathways including MAPK signaling cascades (p Parp1{sup −/−} ES cells. In quantitative analyses of miRNA expression, miR365-3p, let-7a-5p, miR196b-5p, miR203-3p, miR98-5p, and miR146a-5p were increased by ≥ 2-fold in Parp1{sup −/−} ES cell-derived exosomes. Gene ontology enrichment analyses revealed that the upregulated miRNAs were significantly annotated for growth and stress-related cell signaling and cell communication (p Parp1 deficiency in ES cells led to inhibition of cell–cell communication, possibly by intercellular signal transduction, suggesting that Parp1 functions extracellularly by regulating exosomal miRNAs.

60 APPLIED LIFE SCIENCES↗

Exosomes secreted by placental stem cells selectively inhibit growth of aggressive prostate cancer cells

Highlights: • Detailed characterization of exosomes secreted by human placental stem cells (PLSC{sup Exo}) . • Identified anti-cancer efficacy of PLSC{sup Exo} against aggressive prostate cancer cells. • Retinoic acid receptor/Liver x receptor pathway seems central to PLSC{sup Exo} biological effects. The current paradigm in the development of new cancer therapies is the ability to target tumor cells while avoiding harm to noncancerous cells. Furthermore, there is a need to develop novel therapeutic options against drug-resistant cancer cells. Herein, we characterized the placental-derived stem cell (PLSC) exosomes (PLSC{sup Exo}) and evaluated their anti-cancer efficacy in prostate cancer (PCa) cell lines. Nanoparticle tracking analyses revealed the size distribution (average size 131.4 ± 0.9 nm) and concentration of exosomes (5.23 × 10{sup 10}±1.99 × 10{sup 9} per ml) secreted by PLSC. PLSC{sup Exo} treatment strongly inhibited the viability of enzalutamide-sensitive and -resistant PCa cell lines (C4-2B, CWR-R1, and LNCaP cells). Interestingly, PLSC{sup Exo} treatment had no effect on the viability of a non-neoplastic human prostate cell line (PREC-1). Mass spectrometry (MS) analyses showed that PLSC{sup Exo} are loaded with 241 proteins and mainly with saturated fatty acids. Further, Ingenuity Pathway Analysis analyses of proteins loaded in PLSC{sup Exo} suggested the role of retinoic acid receptor/liver x receptor pathways in their biological effects. Together, these results suggest the novel selective anti-cancer effects of PLSC{sup Exo} against aggressive PCa cells.

60 APPLIED LIFE SCIENCES↗

Adipose mesenchymal stem cell-derived exosomes stimulated by hydrogen peroxide enhanced skin flap recovery in ischemia-reperfusion injury

Highlights: • Exosomes derived from ADSCs (ADSC-exos) served as a novel therapeutic alternative for a skin flap. • ADSC-exos treatment is effective for enhancing skin flap recovery and angiogenesis following I/R injury. • ADSC-exos treatment significantly reduced inflammation and apoptosis in the skin flap in I/R injury. • Exosomes derived from ADSCs stimulated by low concentration of H{sub 2}O{sub 2} have better effects in skin flap recovery. • Low concentrations of H{sub 2}O{sub 2} stimulation may serve as a promising pretreatment for exosome-based skin flap survival. Mesenchymal stem cell (MSC)-derived exosomes have been recognized as new candidates for the treatment of ischemic disease or injury and may be an alternative treatment for cell therapy. This aim of the study was to evaluate whether exosomes derived from adipose mesenchymal stem cell (ADSC) can protect the skin flap during ischemia-reperfusion (I/R) injury and induce neovascularization.

60 APPLIED LIFE SCIENCES↗

Aging impairs beige adipocyte differentiation of mesenchymal stem cells via the reduced expression of Sirtuin 1

Highlights: • Aging impaired beige adipocyte differentiation of AT-MSC by induction of senescence. • The induced senescence in elderly AT-MSC caused by reduction of Sirt1 and Sirt3. • Sirt1 activated beige adipocyte differentiation of elderly AT-MSC via p53/p21 pathway. In the body, different types of adipose tissue perform different functions, with brown and beige adipose tissues playing unique roles in dissipating energy. Throughout life, adipocytes are regenerated from progenitors, and this process is impaired by aging. One of the progenitors of adipocytes are mesenchymal stem cells (MSCs), which have recently become a promising tool for stem cell therapy. However, whether or not aging impairs the brown/beige adipocyte differentiation of adipose tissue-derived MSCs (AT-MSCs) remains unclear. In the present study, we isolated AT-MSCs from two different age groups of donors (infants and elderly subjects) and examined the effects of aging on the AT-MSC brown/beige adipocyte differentiation ability. We found that none of the AT-MSCs expressed Myf5, which indicated the beige (not brown) differentiation ability of cells. Of note, an inverse correlation was noted between the beige adipocyte differentiation ability and age, with AT-MSCs derived from elderly donors showed the most severely reduced function due to induced cellular senescence. The impaired expression of Sirtuin 1 (Sirt1) and Sirt3 proved to be responsible for the induction of senescence in elderly AT-MSCs; however, only Sirt1 was directly involved in the regulation of beige adipocyte differentiation. The overexpression of Sirt1 impaired the p53/p21 pathway, thereby preventing elderly AT-MSCs from entering senescence and restoring the beige differentiation ability. Thus, our study represents the important role of Sirt1 and senescence in the regulation of beige adipocyte differentiation during aging.

60 APPLIED LIFE SCIENCES↗

Transplantation of CREG modified embryonic stem cells improves cardiac function after myocardial infarction in mice

Engraftment of embryonic stem cells (ESC) has been proposed as a potential therapeutic approach for post-infarction cardiac dysfunction. However, only mild function improvement has been achieved due to low survival rate and paracrine dysfunction of transplanted stem cells. Cellular repressor of E1A stimulated genes (CREG) has been reported to be a secreted glycoprotein implicated in promoting survival and differentiation of many cell types. Therefore we hypothesized that transplantation of genetically modified ESC with CREG (CREG-ESC) can improve cardiac function after myocardial infarction in mice. A total of 2 × 10{sup 5} CREG-ESC or EGFP-ESC were engrafted into the border zone in a myocardial infarction model in mice. Cardiac function, infarct size and fibrosis at 4 weeks, survival of transplanted ESC, apoptosis and cytokine level of heart tissue, and teratoma formation were assessed in vivo. Apoptosis of ESC under inflammatory stimuli and cardiac differentiation of ESC were investigated in vitro. After 4 weeks, we found transplantation of CREG-ESC could significantly improve cardiac function, ameliorate cardiac remodeling, and reduce infarct size and fibrosis area. Transplantation of CREG-ESC remarkably increased ESC survival in the border zone and inhibited apoptosis of cardiomyocytes. Furthermore, the decrease of inflammatory factors (IL-1β, IL-6 and TNF-α) and increase of anti-inflammatory factors (TGF-β, bFGF and VEGF165) in the border zone were higher in CREG-ESC transplanted hearts. Safety evaluation showed that all transplantation at 2 × 10{sup 5} per heart dose produced no teratoma. Surprisingly, the mice with 3.0 × 10{sup 6} CREG-ESC transplantation was demonstrated teratoma free without cardiac rhythm disturbances in contrast to 100% teratoma formation and rhythm abnormality for the same dose of EGFP-ESC transplantation. In addition, overexpression of CREG inhibits ESC apoptosis and enhanced their differentiation into cardiomyocytes in vitro. Transplantation of CREG-modified ESC exhibits a favorable survival pattern in infarcted hearts, which translates into a substantial preservation of cardiac function after acute myocardial infarction.

60 APPLIED LIFE SCIENCES↗

Synchronous firing patterns of induced pluripotent stem cell-derived cortical neurons depend on the network structure consisting of excitatory and inhibitory neurons

Highlights: • Induced pluripotent stem cells yielded excitatory and inhibitory cortical neurons. • Neurons spontaneously fired and functionally matured on microelectrode arrays. • Firing patterns depended on the in vitro neuronal network structure. The balance between glutamate-mediated excitation and GABA-mediated inhibition is critical to cortical functioning. However, the contribution of network structure consisting of the both neurons to cortical functioning has not been elucidated. We aimed to evaluate the relationship between the network structure and functional activity patterns in vitro. We used mouse induced pluripotent stem cells (iPSCs) to construct three types of neuronal populations; excitatory-rich (Exc), inhibitory-rich (Inh), and control (Cont). Then, we analyzed the activity patterns of these neuronal populations using microelectrode arrays (MEAs). Inhibitory synaptic densities differed between the three types of iPSC-derived neuronal populations, and the neurons showed spontaneously synchronized bursting activity with functional maturation for one month. Moreover, different firing patterns were observed between the three populations; Exc demonstrated the highest firing rates, including frequent, long, and dominant bursts. In contrast, Inh demonstrated the lowest firing rates and the least dominant bursts. Synchronized bursts were enhanced by disinhibition via GABA{sub A} receptor blockade. The present study, using iPSC-derived neurons and MEAs, for the first time show that synchronized bursting of cortical networks in vitro depends on the network structure consisting of excitatory and inhibitory neurons.

60 APPLIED LIFE SCIENCES↗

Mesenchymal stem cells drive paclitaxel resistance in ErbB2/ErbB3-coexpressing breast cancer cells via paracrine of neuregulin 1

We had previously demonstrated that increased expression of ErbB3 is required for ErbB2-mediated paclitaxel resistance in breast cancer cells. In the present study, we have explored the possible role of mesenchymal stem cells (MSCs) in regulating the paclitaxel-sensitivity of ErbB2/ErbB3-coexpressing breast cancer cells. We show that human umbilical cord-derived MSCs express significantly higher level of neuregulin-1 as compared with ErbB2/ErbB3-coexpressing breast cancer cells themselves. Coculture or treatment with conditioned medium of MSCs not only decreases the anti-proliferation effect of paclitaxel on ErbB2/ErbB3-coexpressing breast cancer cells, but also significantly inhibits paclitaxel-induced apoptosis. We further demonstrate that this MSCs-drived paclitaxel resistance in ErbB2/ErbB3-coexpressing breast cancer cells could be attributed to upregulation of Survivin via paracrine effect of NRG-1/ErbB3/PI-3K/Akt signaling, as either specific knockdown expression of ErbB3, or blocking of downstream PI-3K/Akt signaling, or specific inhibition of Survivin can completely reverse this effect. Moreover, targeted knockdown of NRG-1 expression in MSCs abrogates theirs effect on paclitaxel sensitivity of ErbB2/ErbB3-coexpressing breast cancer cells. Taken together, our study indicate that paracrine of NRG-1 by MSCs induces paclitaxel resistance in ErbB2/ErbB3-coexpressing breast cancer cells through PI-3K/Akt signaling-dependent upregulation of Survivin. Our findings suggest that simultaneously targeting mesenchymal stem cells in tumor microenvironment may be a novel strategy to overcome paclitaxel resistance in patients with ErbB2/ErbB3-coexpressing breast cancer.

60 APPLIED LIFE SCIENCES↗

Cardiac extracellular matrix hydrogel together with or without inducer cocktail improves human adipose tissue-derived stem cells differentiation into cardiomyocyte–like cells

Studies have demonstrated that differentiation of stem cells into cardiomyocytes is a complex phenomenon that requires sufficient inducing factors at various time points. Cardiac extracellular matrix (cECM) could provide tissue specific microenvironment and act as an inductive template for efficient cell differentiation. The aim of this study was to investigate the effect of cECM on differentiation of human adipose tissue-derived stem cells (hADSCs) into cardiomyocytes using cECM hydrogel in combination with a cardiac inductive cocktail. hADSCs were cultured on ECM-coated plates with and without inductive cocktail for 3weeks. qRT-PCR and western blot analysis were used to evaluate the expression pattern of special cardiac genes and proteins. When hADSCs were cultured in the presence of cECM cardiac genes including GATA4, HAND1, HAND2, NKX2.5, Troponin I, βMHC, Connexin43 were highly expressed in differentiated cells. Also Connexin43, cTnI and βMHC proteins were expressed as well. We could show that cECM by itself could affect viability, proliferation and differentiation of hADSCs. However, combination of cECM with a cardiac inducing cocktail could improve the results.

60 APPLIED LIFE SCIENCES↗

Effects of amiloride on physiological activity of stem cells of human lung cancer and possible mechanism

Lung cancer is a common malignant tumor, the cancer stem cells (CSCs) were regarded responsible for the development of cancer tissue. The effects of amiloride on lung cancer stem cells and the possible mechanism were not much investigated. In this study, human NCI-H1975 lung CSCs were selected by flow cytometry, and the effects of amiloride at different concentrations (0, 12.5, 25, 50, and 100 μmol/L) were evaluated on proliferation, migration, invasion and apoptosis of CSCs using cell counting kit-8 and Transwell migration assays as well as flow cytometry. Wstern blot analysis was performed to investigate the effect of amiloride on the level of proteins in uPA system, NF-kB pathway, and PI3K-AKT-mTOR pathway in CSCs. As a result, we found that amiloride inhibited proliferation, migration and invasion of lung CSCs, and promoted apoptosis. Further, we found that amiloride decreased levels of target proteins in the uPA system, as well as the NF-kB and PI3K-AKT-mTOR pathways. These results indicated that amiloride could inhibit proliferation, migration and invasion of lung CSCs, and promotes apoptosis, these effects may be related to decreased levels of proteins in the uPA system, the NF-kB pathway, and the PI3K-AKT-mTOR pathway.

60 APPLIED LIFE SCIENCES↗

Intravenous mesenchymal stem cell-derived exosomes ameliorate myocardial inflammation in the dilated cardiomyopathy

Mesenchymal stem cells (MSCs) have been shown to be efficacy to attenuating cardiovascular inflammation; however, there are many limitations to stem cell treatment. Present study was to prove MSC-derived exosomes (MSC-Exos) could alleviating inflammatory cardiomyopathy by improving the inflammatory microenvironment of myocardium, especially by regulating the activity of macrophages. Mice were intraperitoneal injected of doxorubicin (DOX) to establish a dilated cardiomyopathy (DCM) model, and then received intravenous injection of either MSC-Exos or PBS as control. Mice receiving MSC-Exos showed improved cardiac function via echocardiography and attenuated cardiac dilation via HE staining, as well as reduced cardiomyocytes apoptosis. Expression levels of inflammatory factors were reduced. And there was a significant decrease of the inflammatory cells infiltration in the MSC-Exos treatment group comparing to the PBS group. Meanwhile, MSC-Exos could remarkably attenuate the pro-inflammatory macrophages amount in both blood and heart, which was proved that MSC-Exos relied on the JAK2-STAT6 pathway mediating macrophages activation. MSC-Exos improved the inflammatory microenvironment of dilated cardiomyopathy by regulating the polarization of the macrophage, which may hold promise for dilated cardiomyopathy clinical therapy.

60 APPLIED LIFE SCIENCES↗

Valproic acid promotes the neuronal differentiation of spiral ganglion neural stem cells with robust axonal growth

Highlights: • Hearing loss occurs with loss of both hair cells and spiral ganglion neurons (SGNs). • SGN-neural stem cells (NSCs) may be a source of SGN regeneration. • Valproic acid (VPA) induces neural differentiation of SGNs and inhibits their proliferation. • VPA-treated SGN-NSCs show longer neurite outgrowths than those cultured without bFGF. • The effects of VPA are related to Wnt/β-catenin signaling activation. Hearing loss occurs with the loss of hair cells of the cochlea and subsequent degeneration of spiral ganglion neurons (SGNs). Regeneration of SGNs is a potentially promising therapeutic approach to hearing loss in addition to the use of a cochlear implant (CI), because this device stimulates SGNs directly to restore hearing bypassing the missing hair cells. The presence of SGN-neural stem cells (NSCs) has been reported in adult human and mice. These cells have the potential to become SGNs and thus represent a cellular foundation for regeneration therapies for hearing loss. Valproic acid (VPA) has been shown to influence the neural differentiation of NSCs through multiple signaling pathways involving glycogen synthase kinase3β (GSK3β). Our present study therefore aimed to modulate the neural differentiation potential of SGN-NSCs by treatment with VPA. We here report that a clinically relevant concentration of 1 mM VPA induced the differentiation of basic fibroblast growth factor (bFGF)-treated P1- and P14-SGN-NSCs into neuronal and glial cells, confirmed by neuronal marker (Tuj1 and MAP2) and glial cell marker (GFAP and S100β) detection. VPA-treated cells also promoted much longer neurite outgrowth compared to differentiated cells cultured without bFGF. The effects of VPA on the regulation of differentiation may be related to the activation of the Wnt/β-catenin signaling pathway, but not the inhibition of histone deacetylases (HDACs). We propose that VPA has the potential to convert SGN-NSCs into SGNs and thereby restore hearing when combined with a CI.

60 APPLIED LIFE SCIENCES↗