The Experts below are selected from a list of 4398 Experts worldwide ranked by ideXlab platform
Laura Smith A Callahan - One of the best experts on this subject based on the ideXlab platform.
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effect of laminin derived peptides ikvav and lre tethered to hyaluronic acid on hipsc derived neural stem cell morphology attachment and Neurite Extension
Journal of Functional Biomaterials, 2020Co-Authors: Hiran T Perera, Laura Smith A CallahanAbstract:Low neural tissue extracellular matrix (ECM) content has led to the understudy of its effects on neural cells and tissue. Hyaluronic acid (HA) and laminin are major neural ECM components, but direct comparisons of their cellular effects could not be located in the literature. The current study uses human-induced pluripotent stem-cell-derived neural stem cells to assess the effects of HA, laminin, and HA with laminin-derived peptides IKVAV and LRE on cellular morphology, attachment, Neurite Extension and ECM remodeling. Increased attachment was observed on HA with and without IKVAV and LRE compared to laminin. Cellular morphology and Neurite Extension were similar on all surfaces. Using a direct binding inhibitor of Cav2.2 voltage gated calcium channel activity, a known binding partner of LRE, reduced attachment on HA with and without IKVAV and LRE and altered cellular morphology on surfaces with laminin or IKVAV and LRE. HA with IKVAV and LRE reduced the fluorescent intensity of fibronectin staining, but did not alter the localization of ECM remodeling enzymes matrix metalloprotease 2 and 9 staining compared to HA. Overall, the data indicate HA, IKVAV and LRE have complementary effects on human-induced pluripotent stem-cell-derived neural stem cell behavior.
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manipulation of extracellular matrix remodeling and Neurite Extension by mouse embryonic stem cells using ikvav and lre peptide tethering in hyaluronic acid matrices
Biomacromolecules, 2019Co-Authors: Hiran T Perera, Laura Smith A Callahan, Skyler M HowellAbstract:Cellular remodeling of the matrix has recently emerged as a key factor in promoting neural differentiation. Most strategies to manipulate matrix remodeling focus on proteolytically cleavable cross-linkers, leading to changes in tethered biochemical signaling and matrix properties. Using peptides that are not the direct target of enzymatic degradation will likely reduce changes in the matrix and improve control of biological behavior. In this study, laminin-derived peptides, IKVAV and LRE, tethered to independent sites in hyaluronic acid matrices using Michael addition and strain-promoted azide-alkyne cycloaddition are sufficient to manipulate hyaluronic acid degradation, gelatinase expression, and protease expression, while promoting Neurite Extension through matrix metalloprotease-dependent mechanisms in mouse embryonic stem cells encapsulated in hyaluronic acid matrices using an oxidation-reduction reaction initiated gelation. This study provides the foundation for a new strategy to stimulate matrix remodeling that is not dependent on enzymatic cleavage targets.
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Neurite Extension and neuronal differentiation of human induced pluripotent stem cell derived neural stem cells on polyethylene glycol hydrogels containing a continuous young s modulus gradient
Journal of Biomedical Materials Research Part A, 2017Co-Authors: Matthew C Mosley, Jing Chen, Yueh Hsun Yang, Shenglan Li, Laura Smith A CallahanAbstract:Mechanotransduction in neural cells involves multiple signaling pathways that are not fully understood. Differences in lineage and maturation state are suggested causes for conflicting reports on neural cell mechanosensitivity. To optimize matrices for use in stem cell therapy treatments transplanting human induced pluripotent stem cell derived neural stem cells (hNSC) into lesions after spinal cord injury, the effects of Young's Modulus changes on hNSC behavior must be understood. The present study utilizes polyethylene glycol hydrogels containing a continuous gradient in Young's modulus to examine changes in the Young's Modulus of the culture substrate on hNSC Neurite Extension and neural differentiation. Changes in the Young's Modulus of the polyethylene glycol hydrogels was found to affect Neurite Extension and cellular organization on the matrices. hNSC cultured on 907 Pa hydrogels were found to extend longer Neurites than hNSC cultured on other tested Young's Moduli hydrogels. The gene expression of β tubulin III and microtubule-associated protein 2 in hNSC was affected by changes in the Young's Modulus of the hydrogel. The combinatory method approach used in the present study demonstrates that hNSC are mechanosensitive and the matrix Young's Modulus should be a design consideration for hNSC transplant applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 824–833, 2017.
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directed differentiation and Neurite Extension of mouse embryonic stem cell on aligned poly lactide nanofibers functionalized with yigsr peptide
Biomaterials, 2013Co-Authors: Laura Smith A Callahan, Ian A Barker, Jukuan Zheng, Darrell H Reneker, Andrew P Dove, Matthew L BeckerAbstract:End-functional PLLA nanofibers were fabricated into mats of random or aligned fibers and functionalized post-spinning using metal-free “click chemistry” with the peptide Tyr-Ile-Gly-Ser-Arg (YIGSR). Fibers that were both aligned and functionalized with YIGSR were found to significantly increase the fraction of mouse embryonic stem cells (mESC) expressing neuron-specific class III beta-tubulin (TUJ1), the level of Neurite Extension and gene expression for neural markers compared to mESC cultured on random fiber mats and unfunctionalized matrices. Precise functionalization of degradable polymers with bioactive peptides created translationally-relevant materials that capitalize on the advantages of both synthetic and natural systems, while mitigating the classic limitations of each.
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concentration dependent neural differentiation and Neurite Extension of mouse esc on primary amine derivatized surfaces
Biomaterials Science, 2013Co-Authors: Laura Smith A Callahan, Christopher M Stafford, Matthew L BeckerAbstract:Cell sourcing continues to be a significant limitation to regenerative medicine especially in neural lineages where population heterogeneity during in vitro culture prevents definitive phenotype assessment. For nearly 40 years, the biological community has worked with amine-derivated surfaces and hydrogels, especially alginate, with little quantitative assessment of how local amine concentration influences the extent of neural differentiation and Neurite Extension. In this manuscript we show that the local concentration of amines distinctly influences mouse embryonic stem cell (ESC) lineage commitment and the length of Neurite Extensions both of which are early indicators of differentiation. The well-defined amine gradients are a highly relevant tool for identifying these critical concentrations and thresholds. We feel these results will be of critical importance to researchers developing new ex vivo culture materials for neural applications as well as the community exploring nerve regeneration in vivo.
Ravi V Bellamkonda - One of the best experts on this subject based on the ideXlab platform.
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role of fibronectin in topographical guidance of Neurite Extension on electrospun fibers
Biomaterials, 2011Co-Authors: Vivek Mukhatyar, Manuel Salmeronsanchez, Soumon Rudra, Shoumit Mukhopadaya, Thomas H Barker, Andres J Garcia, Ravi V BellamkondaAbstract:Bridging of long peripheral nerve gaps remains a significant clinical challenge. Electrospun nanofibers have been used to direct and enhance Neurite Extension in vitro and in vivo. While it is well established that oriented fibers influence Neurite outgrowth and Schwann cell migration, the mechanisms by which they influence these cells are still unclear. In this study, thin films consisting of aligned poly-acrylonitrile methylacrylate (PAN-MA) fibers or solvent casted smooth, PAN-MA films were fabricated to investigate the potential role of differential protein adsorption on topography-dependent neural cell responses. Aligned nanofiber films promoted enhanced adsorption of fibronectin compared to smooth films. Studies employing function-blocking antibodies against cell adhesion motifs suggest that fibronectin plays an important role in modulating Schwann cell migration and Neurite outgrowth from dorsal root ganglion (DRG) cultures. Atomic Force Microscopy demonstrated that aligned PAN-MA fibers influenced fibronectin distribution, and promoted aligned fibronectin network formation compared to smooth PAN-MA films. In the presence of topographical cues, Schwann cell-generated fibronectin matrix was also organized in a topographically sensitive manner. Together these results suggest that fibronectin adsorption mediated the ability of topographical cues to influence Schwann cell migration and Neurite outgrowth. These insights are significant to the development of rational approaches to scaffold designs to bridge long peripheral nerve gaps.
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anisotropic scaffolds facilitate enhanced Neurite Extension in vitro
Journal of Biomedical Materials Research Part A, 2006Co-Authors: Mahesh Chandra Dodla, Ravi V BellamkondaAbstract:Tissue engineering (TE) techniques to enhance nerve regeneration following nerve damage have had limited success in matching the performance of autografts across short nerve gaps (< 10 mm). For regeneration over longer nerve gaps, TE techniques have been less successful than autografts. Most engineered scaffolds do not present directional cues to the regenerating nerves. In our efforts to design a TE scaffold to replace the autograft, we hypothesize that anisotropic hydrogel scaffolds with gradients of a growth-promoting glycoprotein, laminin-1 (LN-1), may promote directional Neurite Extension and enhance regeneration. In this study we report the engineering of three-dimensional (3D) agarose scaffolds with photoimmobilized gradients of LN-1 of differing slopes. Dorsal root ganglia (DRG) from chicken embryos were cultured in the agarose scaffolds and their Neurite Extension rate was determined. DRG Neurite Extension rates were significantly higher in the anisotropic scaffolds, with a maximal growth rate in an anisotropic scaffold twice that of the maximal growth rate in isotropic scaffolds of LN-1. We suggest that these anisotropic scaffolds, presenting an optimal gradient of LN-1, may significantly impact nerve regeneration. Such anisotropic scaffolds may represent a new generation of tissue engineered materials with built-in directional cues for guided tissue or nerve regeneration.
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cs 4 6 is differentially upregulated in glial scar and is a potent inhibitor of Neurite Extension
Molecular and Cellular Neuroscience, 2005Co-Authors: Ryan J Gilbert, Ravi V Bellamkonda, Robert J Mckeon, Aniq B Darr, Anthony Calabro, Vincent C HascallAbstract:The precise contribution of different CS-GAGs to CSPG-mediated inhibition of axonal growth after CNS injury is unknown. Quantification of the CS-GAGs in uninjured and injured brain (scar tissue) using fluorophore-assisted carbohydrate electrophoresis (FACE) demonstrated that the dominant CS-GAG in the uninjured brain is CS-4 whereas, in glial scar, CS-2, CS-6, and CS-4,6 were over-expressed. To determine if the pattern of sulfation influenced Neurite Extension, we compared the effects of CS-GAGs with dominant CS-4, CS-6, or CS-4,6 sulfation to intact CSPG (aggrecan), chondroitin (CS-0), and hyaluronan on chick DRG Neurite outgrowth. We report that CS-4,6 GAG, one of the upregulated CS-GAGs in astroglial scar, is potently inhibitory and is comparable to intact aggrecan, a CSPG with known inhibitory properties. Thus, a specific CS-GAG that is differentially over-expressed in astroglial scar is a potent inhibitor of Neurite Extension. These results may influence the design of more specific strategies to enhance CNS regeneration after injury.
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modulation of rho gtpase activity alleviates chondroitin sulfate proteoglycan dependent inhibition of Neurite Extension
Journal of Neuroscience Research, 2004Co-Authors: Anjana Jain, Ravi V Bellamkonda, Susann M BradykalnayAbstract:The central nervous system (CNS) fails to regenerate after injury. A glial scar forms at the injury site, contributing to regenerative failure partly resulting from the chondroitin sulfate proteoglycans (CSPGs) in the glial scar. The family of Rho GTPases, which includes Cdc42, Rac1, and RhoA, is involved in growth cone dynamics. Although the response of neural cells to the inactivation of Rho when contacting myelin-related substrates, or CSPG, has been investigated, Rac1's and Cdc42's abilities to modulate CSPG-dependent inhibition have yet to be explored. In this study, a stripe assay was utilized to examine the effects of modulating all three Rho GTPases on Neurite Extension across inhibitory CSPG lanes. Alternating laminin (LN) and CSPG lanes were created and NG108-15 cells and E9 chick dorsal root ganglia (DRGs) were cultured on the lanes. By using the protein delivery agent Chariot, the neuronal response to exposure of constitutively active (CA) and dominant negative (DN) mutants of the Rho GTPases, along with the bacterial toxin C3, was determined by quantifying the percentage ratio of Neurites crossing the CSPG lanes. CA-Cdc42, CA-Rac1, and C3 transferase significantly increased the number of Neurites crossing into the CSPG lanes compared with the negative controls for both the NG108-15 cells and the E9 chick DRGs. We also show that these mutant proteins require the delivery vehicle, Chariot, to enter the neurons and affect Neurite Extension. Therefore, activation of Cdc42 and Rac, as well as inhibition of Rho, helps overcome the CSPG-dependent inhibition of Neurite Extension.
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agarose gel stiffness determines rate of drg Neurite Extension in 3d cultures
Biomaterials, 2001Co-Authors: A P Balgude, A Szymanski, Ravi V BellamkondaAbstract:The optimization of scaffold mechanical properties for Neurite Extension is critical for neural tissue engineering. Agarose hydrogels can be used to stimulate and maintain three-dimensional Neurite Extension from primary sensory ganglia in vitro. The present study explores the structure-function relationship between dorsal root ganglion (DRG) Neurite Extension and agarose gel mechanical properties. A range of agarose gels of differing concentrations were generated and the corresponding rate of E9 DRG Neurite Extension was measured. Rate of Neurite Extension was inversely correlated to the mechanical stiffness of agarose gels in the range of 0.75-2.00% (wt/vol) gel concentrations. In addition, we postulate a physical model that predicts the rate of Neurite Extension in agarose gels, if gel stiffness is a known parameter. This model is based on Heidemann and Buxbaum's model of Neurite Extension. These results, if extended to scaffolds of other morphological and chemical features, would contribute significantly to the design criteria of three-dimensional scaffolds for neural tissue engineering.
Christine E Schmidt - One of the best experts on this subject based on the ideXlab platform.
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nerve growth factor immobilized polypyrrole bioactive electrically conducting polymer for enhanced Neurite Extension
Journal of Biomedical Materials Research Part A, 2007Co-Authors: Natalia Gomez, Christine E SchmidtAbstract:Biomaterials that present multiple stimuli are attractive for a number of biomedical applications. In particular, electrical and biological cues are important factors to include in interfaces with neurons for applications such as nerve conduits and neural probes. Here, we report the combination of these two stimuli, by immobilizing nerve growth factor (NGF) on the surface of the electrically conducting polymer polypyrrole (PPy). NGF was immobilized using an intermediate linker provided by a layer of polyallylamine conjugated to an arylazido functional group. Upon exposure to UV light and activation of the azido groups, NGF was fixed to the substrate. Three different surface concentrations were obtained (0.21-0.98 ng/mm(2)) and similar levels of Neurite Extension were observed on immobilized NGF as with soluble NGF. Additionally, electrical stimulation experiments were conducted with the modified polymer and revealed a 50% increase in Neurite outgrowth in PC12 cells compared to experiments without electrical stimulation. This novel modification of PPy provides both electrical and biological stimulation, by presenting tethered growth factors and only producing a small decrease in the material's properties (conductivity approximately 10 S cm(-1)) when compared to other modification techniques (conductivity approximately 10(-3)-10(-6) S cm(-1)).
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nerve growth factor immobilized polypyrrole bioactive electrically conducting polymer for enhanced Neurite Extension
Journal of Biomedical Materials Research Part A, 2007Co-Authors: Natalia Gomez, Christine E SchmidtAbstract:Biomaterials that present multiple stimuli are attractive for a number of biomedical applications. In particular, electrical and biological cues are important factors to include in interfaces with neurons for applications such as nerve conduits and neural probes. Here, we report the combination of these two stimuli, by immobilizing nerve growth factor (NGF) on the surface of the electrically conducting polymer polypyrrole (PPy). NGF was immobilized using an intermediate linker provided by a layer of polyallylamine conjugated to an arylazido functional group. Upon exposure to UV light and activation of the azido groups, NGF was fixed to the substrate. Three different surface concentrations were obtained (0.21–0.98 ng/mm2) and similar levels of Neurite Extension were observed on immobilized NGF as with soluble NGF. Additionally, electrical stimulation experiments were conducted with the modified polymer and revealed a 50% increase in Neurite outgrowth in PC12 cells compared to experiments without electrical stimulation. This novel modification of PPy provides both electrical and biological stimulation, by presenting tethered growth factors and only producing a small decrease in the material's properties (conductivity ∼10 S cm−1) when compared to other modification techniques (conductivity ∼10−3–10−6 S cm−1). © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
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effects of collagen 1 fibronectin laminin and hyaluronic acid concentration in multi component gels on Neurite Extension
Journal of Biomaterials Science-polymer Edition, 2007Co-Authors: Curt Deister, Samer Aljabari, Christine E SchmidtAbstract:Recovery after peripheral nerve injury remains a significant challenge. Extracellular matrix proteins and hydrogels of extracellular matrix components have been shown to improve regeneration in peripheral nerve entubulation models, especially over long distances. The chemical properties, ligand identity and density, and mechanical properties of the hydrogel can affect Neurite Extension. However, the importance of combinatorial effects between different components in co-gels of several extracellular matrix components is unclear. In this study, we investigated Neurite Extension from explanted dorsal root ganglia cultured within co-gels made from laminin, fibronectin, collagen 1 and hyaluronic acid. Laminin had a strong, dose-dependent effect on both Neurite length and outgrowth. Fibronectin was slightly, but generally not significantly, inhibitory to Neurite Extension. The concentration of collagen 1 and hyaluronic acid did not have significant effects on Neurite Extension. The combinatorial effects among t...
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effects of collagen 1 fibronectin laminin and hyaluronic acid concentration in multi component gels on Neurite Extension
Journal of Biomaterials Science-polymer Edition, 2007Co-Authors: Curt Deister, Samer Aljabari, Christine E SchmidtAbstract:Recovery after peripheral nerve injury remains a significant challenge. Extracellular matrix proteins and hydrogels of extracellular matrix components have been shown to improve regeneration in peripheral nerve entubulation models, especially over long distances. The chemical properties, ligand identity and density, and mechanical properties of the hydrogel can affect Neurite Extension. However, the importance of combinatorial effects between different components in co-gels of several extracellular matrix components is unclear. In this study, we investigated Neurite Extension from explanted dorsal root ganglia cultured within co-gels made from laminin, fibronectin, collagen 1 and hyaluronic acid. Laminin had a strong, dose-dependent effect on both Neurite length and outgrowth. Fibronectin was slightly, but generally not significantly, inhibitory to Neurite Extension. The concentration of collagen 1 and hyaluronic acid did not have significant effects on Neurite Extension. The combinatorial effects among the four components were additive rather than synergistic. A co-gel made with 1.5 mg/ml collagen 1 and 1.5 mg/ml laminin was optimum in this study, resulting in an average Neurite length of 1532 +/- 91 microm versus 976 +/- 32 microm for controls, and an increase in overall volume outgrowth (reflecting Neurite length and branching) of 85.9+/-9.3% over controls. This co-gel provides a mechanically stable scaffold with high ligand density and biochemical affinity. The results of this study support the use of co-gels of laminin and collagen 1 for promoting regeneration in peripheral nerve injuries and suggest that interactions among hydrogel components are not significant.
Natalia Gomez - One of the best experts on this subject based on the ideXlab platform.
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nerve growth factor immobilized polypyrrole bioactive electrically conducting polymer for enhanced Neurite Extension
Journal of Biomedical Materials Research Part A, 2007Co-Authors: Natalia Gomez, Christine E SchmidtAbstract:Biomaterials that present multiple stimuli are attractive for a number of biomedical applications. In particular, electrical and biological cues are important factors to include in interfaces with neurons for applications such as nerve conduits and neural probes. Here, we report the combination of these two stimuli, by immobilizing nerve growth factor (NGF) on the surface of the electrically conducting polymer polypyrrole (PPy). NGF was immobilized using an intermediate linker provided by a layer of polyallylamine conjugated to an arylazido functional group. Upon exposure to UV light and activation of the azido groups, NGF was fixed to the substrate. Three different surface concentrations were obtained (0.21-0.98 ng/mm(2)) and similar levels of Neurite Extension were observed on immobilized NGF as with soluble NGF. Additionally, electrical stimulation experiments were conducted with the modified polymer and revealed a 50% increase in Neurite outgrowth in PC12 cells compared to experiments without electrical stimulation. This novel modification of PPy provides both electrical and biological stimulation, by presenting tethered growth factors and only producing a small decrease in the material's properties (conductivity approximately 10 S cm(-1)) when compared to other modification techniques (conductivity approximately 10(-3)-10(-6) S cm(-1)).
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nerve growth factor immobilized polypyrrole bioactive electrically conducting polymer for enhanced Neurite Extension
Journal of Biomedical Materials Research Part A, 2007Co-Authors: Natalia Gomez, Christine E SchmidtAbstract:Biomaterials that present multiple stimuli are attractive for a number of biomedical applications. In particular, electrical and biological cues are important factors to include in interfaces with neurons for applications such as nerve conduits and neural probes. Here, we report the combination of these two stimuli, by immobilizing nerve growth factor (NGF) on the surface of the electrically conducting polymer polypyrrole (PPy). NGF was immobilized using an intermediate linker provided by a layer of polyallylamine conjugated to an arylazido functional group. Upon exposure to UV light and activation of the azido groups, NGF was fixed to the substrate. Three different surface concentrations were obtained (0.21–0.98 ng/mm2) and similar levels of Neurite Extension were observed on immobilized NGF as with soluble NGF. Additionally, electrical stimulation experiments were conducted with the modified polymer and revealed a 50% increase in Neurite outgrowth in PC12 cells compared to experiments without electrical stimulation. This novel modification of PPy provides both electrical and biological stimulation, by presenting tethered growth factors and only producing a small decrease in the material's properties (conductivity ∼10 S cm−1) when compared to other modification techniques (conductivity ∼10−3–10−6 S cm−1). © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Matthew L Becker - One of the best experts on this subject based on the ideXlab platform.
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directed differentiation and Neurite Extension of mouse embryonic stem cell on aligned poly lactide nanofibers functionalized with yigsr peptide
Biomaterials, 2013Co-Authors: Laura Smith A Callahan, Ian A Barker, Jukuan Zheng, Darrell H Reneker, Andrew P Dove, Matthew L BeckerAbstract:End-functional PLLA nanofibers were fabricated into mats of random or aligned fibers and functionalized post-spinning using metal-free “click chemistry” with the peptide Tyr-Ile-Gly-Ser-Arg (YIGSR). Fibers that were both aligned and functionalized with YIGSR were found to significantly increase the fraction of mouse embryonic stem cells (mESC) expressing neuron-specific class III beta-tubulin (TUJ1), the level of Neurite Extension and gene expression for neural markers compared to mESC cultured on random fiber mats and unfunctionalized matrices. Precise functionalization of degradable polymers with bioactive peptides created translationally-relevant materials that capitalize on the advantages of both synthetic and natural systems, while mitigating the classic limitations of each.
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concentration dependent neural differentiation and Neurite Extension of mouse esc on primary amine derivatized surfaces
Biomaterials Science, 2013Co-Authors: Laura Smith A Callahan, Christopher M Stafford, Matthew L BeckerAbstract:Cell sourcing continues to be a significant limitation to regenerative medicine especially in neural lineages where population heterogeneity during in vitro culture prevents definitive phenotype assessment. For nearly 40 years, the biological community has worked with amine-derivated surfaces and hydrogels, especially alginate, with little quantitative assessment of how local amine concentration influences the extent of neural differentiation and Neurite Extension. In this manuscript we show that the local concentration of amines distinctly influences mouse embryonic stem cell (ESC) lineage commitment and the length of Neurite Extensions both of which are early indicators of differentiation. The well-defined amine gradients are a highly relevant tool for identifying these critical concentrations and thresholds. We feel these results will be of critical importance to researchers developing new ex vivo culture materials for neural applications as well as the community exploring nerve regeneration in vivo.