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Nebulized solvent ablation of aligned PLLA fibers for the study of neurite response to anisotropic-to-isotropic fiber/film transition (AFFT) boundaries in astrocyte-neuron co-cultures. Biomaterials 2015; 46:82-94. [PMID: 25678118 DOI: 10.1016/j.biomaterials.2014.12.046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 12/01/2014] [Accepted: 12/16/2014] [Indexed: 12/18/2022]
Abstract
Developing robust in vitro models of in vivo environments has the potential to reduce costs and bring new therapies from the bench top to the clinic more efficiently. This study aimed to develop a biomaterial platform capable of modeling isotropic-to-anisotropic cellular transitions observed in vivo, specifically focusing on changes in cellular organization following spinal cord injury. In order to accomplish this goal, nebulized solvent patterning of aligned, electrospun poly-l-lactic acid (PLLA) fiber substrates was developed. This method produced a clear topographic transitional boundary between aligned PLLA fibers and an isotropic PLLA film region. Astrocytes were then seeded on these scaffolds, and a shift between oriented and non-oriented astrocytes was created at the anisotropic-to-isotropic fiber/film transition (AFFT) boundary. Orientation of chondroitin sulfate proteoglycans (CSPGs) and fibronectin produced by these astrocytes was analyzed, and it was found that astrocytes growing on the aligned fibers produced aligned arrays of CSPGs and fibronectin, while astrocytes growing on the isotropic film region produced randomly-oriented CSPG and fibronectin arrays. Neurite extension from rat dissociated dorsal root ganglia (DRG) was studied on astrocytes cultured on anisotropic, aligned fibers, isotropic films, or from fibers to films. It was found that neurite extension was oriented and longer on PLLA fibers compared to PLLA films. When dissociated DRG were cultured on the astrocytes near the AFFT boundary, neurites showed directed orientation that was lost upon growth into the isotropic film region. The AFFT boundary also restricted neurite extension, limiting the extension of neurites once they grew from the fibers and into the isotropic film region. This study reveals the importance of anisotropic-to-isotropic transitions restricting neurite outgrowth by itself. Furthermore, we present this scaffold as an alternative culture system to analyze neurite response to cellular boundaries created following spinal cord injury and suggest its usefulness to study cellular responses to any aligned-to-unorganized cellular boundaries seen in vivo.
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Venkatasubramaniam A, Drude A, Good T. Role of N-terminal residues in Aβ interactions with integrin receptor and cell surface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2568-77. [DOI: 10.1016/j.bbamem.2014.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 05/26/2014] [Accepted: 06/13/2014] [Indexed: 01/12/2023]
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Jovanov Milošević N, Judaš M, Aronica E, Kostovic I. Neural ECM in laminar organization and connectivity development in healthy and diseased human brain. PROGRESS IN BRAIN RESEARCH 2014; 214:159-78. [DOI: 10.1016/b978-0-444-63486-3.00007-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Beller JA, Kulengowski B, Kobraei EM, Curinga G, Calulot CM, Bahrami A, Hering TM, Snow DM. Comparison of sensory neuron growth cone and filopodial responses to structurally diverse aggrecan variants, in vitro. Exp Neurol 2013; 247:143-57. [PMID: 23458191 DOI: 10.1016/j.expneurol.2013.02.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 02/06/2013] [Accepted: 02/18/2013] [Indexed: 12/20/2022]
Abstract
Following spinal cord injury, a regenerating neurite encounters a glial scar enriched in chondroitin sulfate proteoglycans (CSPGs), which presents a major barrier. There are two points at which a neurite makes contact with glial scar CSPGs: initially, filopodia surrounding the growth cone extend and make contact with CSPGs, then the peripheral domain of the entire growth cone makes CSPG contact. Aggrecan is a CSPG commonly used to model the effect CSPGs have on elongating or regenerating neurites. In this study, we investigated filopodia and growth cone responses to contact with structurally diverse aggrecan variants using the common stripe assay. Using time-lapse imaging with 15-s intervals, we measured growth cone area, growth cone width, growth cone length, filopodia number, total filopodia length, and the length of the longest filopodia following contact with aggrecan. Responses were measured after both filopodia and growth cone contact with five different preparations of aggrecan: two forms of aggrecan derived from bovine articular cartilage (purified and prepared using different techniques), recombinant aggrecan lacking chondroitin sulfate side chains (produced in CHO-745 cells) and two additional recombinant aggrecan preparations with varying lengths of chondroitin sulfate side chains (produced in CHO-K1 and COS-7 cells). Responses in filopodia and growth cone behavior differed between the structurally diverse aggrecan variants. Mutant CHO-745 aggrecan (lacking chondroitin sulfate chains) permitted extensive growth across the PG stripe. Filopodia contact with the CHO-745 aggrecan caused a significant increase in growth cone width and filopodia length (112.7% ± 4.9 and 150.9% ± 7.2 respectively, p<0.05), and subsequently upon growth cone contact, growth cone width remained elevated along with a reduction in filopodia number (121.9% ± 4.2; 72.39% ± 6.4, p<0.05). COS-7 derived aggrecan inhibited neurite outgrowth following growth cone contact. Filopodia contact produced an increase in growth cone area and width (126.5% ± 8.1; 150.3% ± 13.31, p<0.001), and while these parameters returned to baseline upon growth cone contact, a reduction in filopodia number and length was observed (73.94% ± 5.8, 75.3% ± 6.2, p<0.05). CHO-K1 derived aggrecan inhibited neurite outgrowth following filopodia contact, and caused an increase in growth cone area and length (157.6% ± 6.2; 117.0% ± 2.8, p<0.001). Interestingly, the two bovine articular cartilage aggrecan preparations differed in their effects on neurite outgrowth. The proprietary aggrecan (BA I, Sigma-Aldrich) inhibited neurites at the point of growth cone contact, while our chemically purified aggrecan (BA II) inhibited neurite outgrowth at the point of filopodia contact. BA I caused a reduction in growth cone width following filopodia contact (91.7% ± 2.5, p<0.05). Upon growth cone contact, there was a further reduction in growth cone width and area (66.4% ± 2.2; 75.6% ± 2.9; p<0.05), as well as reductions in filopodia number, total length, and max length (75.9% ± 5.7, p<0.05; 68.8% ± 6.0; 69.6% ± 3.5, p<0.001). Upon filopodia contact, BA II caused a significant increase in growth cone area, and reductions in filopodia number and total filopodia length (115.9% ± 5.4, p<0.05; 72.5% ± 2.7; 77.7% ± 3.2, p<0.001). In addition, filopodia contact with BA I caused a significant reduction in growth cone velocity (38.6 nm/s ± 1.3 before contact, 17.1 nm/s ± 3.6 after contact). These data showed that neuron morphology and behavior are differentially dependent upon aggrecan structure. Furthermore, the behavioral changes associated with the approaching growth cone may be predictive of inhibition or growth.
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Affiliation(s)
- Justin A Beller
- Spinal Cord and Brain Injury Research Center, and Department of Anatomy and Neurobiology, University of Kentucky, Lexington, KY 40536, USA
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The roles of neuronal and glial precursors in overcoming chondroitin sulfate proteoglycan inhibition. Exp Neurol 2012; 235:627-37. [PMID: 22498104 DOI: 10.1016/j.expneurol.2012.03.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 03/26/2012] [Indexed: 11/23/2022]
Abstract
The extension of axons through the major inhibitory component of the glial scar, chondroitin sulfate proteoglycans (CSPGs), remains a key obstacle for regeneration following spinal cord injury (SCI). We have previously shown that transplants composed of neuronal and glial restricted precursors (NRP and GRP respectively) promote regeneration and connectivity in the injured spinal cord (Bonner et al., 2010, 2011), however, little is known about the properties of these precursors at a cellular level. We now report that NRP-derived neurons, in contrast to dorsal root ganglion (DRG) neurons, have the ability to extend axons and cross over from a permissive substratum (laminin) onto inhibitory CSPG in vitro. Growth cones of neurons derived from NRP, compared to DRG, exhibit significantly lower levels of the CSPG receptors protein tyrosine phosphatase sigma (PTPσ) and leukocyte common antigen-related phosphatase (LAR). GRP-conditioned medium prepared from the same cell densities did not affect the response of primary sensory neurons to CSPG confirming that the ability of NRP-derived neurons to cross onto CSPG is determined intrinsically. However, GRP-conditioned medium collected from high density cultures increased the probability of DRG axons to cross from LN onto CSPG and increased the length of DRG axons extending on CSPG. Collectively, these results suggest that (1) neurons derived from NRPs are intrinsically insensitive to CSPGs due to low levels of receptor expression, and (2) high levels of factors secreted by GRP can reduce the inhibitory effects of CSPG and promote axonal growth. These observations provide mechanistic insights into the specific roles of NRPs and GRPs in promoting regeneration and repair following SCI.
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Myers JP, Santiago-Medina M, Gomez TM. Regulation of axonal outgrowth and pathfinding by integrin-ECM interactions. Dev Neurobiol 2011; 71:901-23. [PMID: 21714101 PMCID: PMC3192254 DOI: 10.1002/dneu.20931] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Developing neurons use a combination of guidance cues to assemble a functional neural network. A variety of proteins immobilized within the extracellular matrix (ECM) provide specific binding sites for integrin receptors on neurons. Integrin receptors on growth cones associate with a number of cytosolic adaptor and signaling proteins that regulate cytoskeletal dynamics and cell adhesion. Recent evidence suggests that soluble growth factors and classic axon guidance cues may direct axon pathfinding by controlling integrin-based adhesion. Moreover, because classic axon guidance cues themselves are immobilized within the ECM and integrins modulate cellular responses to many axon guidance cues, interactions between activated receptors modulate cell signals and adhesion. Ultimately, growth cones control axon outgrowth and pathfinding behaviors by integrating distinct biochemical signals to promote the proper assembly of the nervous system. In this review, we discuss our current understanding how ECM proteins and their associated integrin receptors control neural network formation.
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Affiliation(s)
- Jonathan P Myers
- Department of Neuroscience, Neuroscience Training Program, University of Wisconsin, Madison, Wisconsin 53706, USA
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Loubet D, Dakowski C, Pietri M, Pradines E, Bernard S, Callebert J, Ardila-Osorio H, Mouillet-Richard S, Launay JM, Kellermann O, Schneider B. Neuritogenesis: the prion protein controls β1 integrin signaling activity. FASEB J 2011; 26:678-90. [PMID: 22038049 DOI: 10.1096/fj.11-185579] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cytoskeleton modifications are required for neuronal stem cells to acquire neuronal polarization. Little is known, however, about mechanisms that orchestrate cytoskeleton remodeling along neuritogenesis. Here, we show that the silencing of the cellular prion protein (PrP(C)) impairs the initial sprouting of neurites upon induction of differentiation of the 1C11 neuroectodermal cell line, indicating that PrP(C) is necessary to neuritogenesis. Such PrP(C) function relies on its capacity to negatively regulate the clustering, activation, and signaling activity of β1 integrins at the plasma membrane. β1 Integrin aggregation caused by PrP(C) depletion triggers overactivation of the RhoA-Rho kinase-LIMK-cofilin pathway, which, in turn, alters the turnover of focal adhesions, increases the stability of actin microfilaments, and in fine impairs neurite formation. Inhibition of Rho kinases is sufficient to compensate for the lack of PrP(C) and to restore neurite sprouting. We also observe an increased secretion of fibronectin in the surrounding milieu of PrP(C)-depleted 1C11 cells, which likely self-sustains β1 integrin signaling overactivation and contributes to neuritogenesis defect. Our overall data reveal that PrP(C) contributes to the acquisition of neuronal polarization by modulating β1 integrin activity, cell interaction with fibronectin, and cytoskeleton dynamics.
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Affiliation(s)
- Damien Loubet
- Institut National Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche en Santé (UMR-S) 747, Paris, France
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Richeri A, Bianchimano P, Crutcher KA, Brauer MM. Reduced sympathetic neurite outgrowth on uterine tissue sections from rats treated with estrogen. Cell Tissue Res 2010; 340:287-301. [DOI: 10.1007/s00441-010-0956-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 02/25/2010] [Indexed: 12/15/2022]
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Comparative screening of glial cell types reveals extracellular matrix that inhibits retinal axon growth in a chondroitinase ABC-resistant fashion. Glia 2009; 57:1420-38. [DOI: 10.1002/glia.20860] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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The glia-derived extracellular matrix glycoprotein tenascin-C promotes embryonic and postnatal retina axon outgrowth via the alternatively spliced fibronectin type III domain TNfnD. ACTA ACUST UNITED AC 2009; 4:271-83. [DOI: 10.1017/s1740925x09990020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Tenascin-C (Tnc) is an astrocytic multifunctional extracellular matrix (ECM) glycoprotein that potentially promotes or inhibits neurite outgrowth. To investigate its possible functions for retinal development, explants from embryonic day 18 (E18) rat retinas were cultivated on culture substrates composed of poly-d-lysine (PDL), or PDL additionally coated with Tnc or laminin (LN)-1, which significantly increased fiber length. When combined with LN, Tnc induced axon fasciculation that reduced the apparent number of outgrowing fibers. In order to circumscribe the stimulatory region, Tnc-derived fibronectin type III (TNfn) domains fused to the human Ig-Fc-fragment TNfnD6-Fc, TNfnBD-Fc, TNFnA1A2-Fc and TNfnA1D-Fc were studied. The fusion proteins TNfnBD-Fc and to a lesser degree TNfnA1D-Fc were stimulatory when compared with the Ig-Fc-fragment protein without insert. In contrast, the combination TNfnA1A2-Fc reduced fiber outgrowth beneath the values obtained for the Ig-Fc domain, indicating potential inhibitory properties. The monoclonal J1/tn2 antibody (clone 578) that is specific for domain TNfnD blocked the stimulatory properties of the TNfn-Fc fusions. When postnatal day 7 retinal ganglion cells were used rather that explants, Tnc and Tnc-derived proteins proved permissive for neurite outgrowth. The present study highlights a strong retinal axon growth-promoting activity of the Tnc domain TNfnD, which is modulated by neighboring domains.
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Nishida Y, Adati N, Ozawa R, Maeda A, Sakaki Y, Takeda T. Identification and classification of genes regulated by phosphatidylinositol 3-kinase- and TRKB-mediated signalling pathways during neuronal differentiation in two subtypes of the human neuroblastoma cell line SH-SY5Y. BMC Res Notes 2008; 1:95. [PMID: 18957096 PMCID: PMC2615028 DOI: 10.1186/1756-0500-1-95] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 10/28/2008] [Indexed: 11/15/2022] Open
Abstract
Background SH-SY5Y cells exhibit a neuronal phenotype when treated with all-trans retinoic acid (RA), but the molecular mechanism of activation in the signalling pathway mediated by phosphatidylinositol 3-kinase (PI3K) is unclear. To investigate this mechanism, we compared the gene expression profiles in SK-N-SH cells and two subtypes of SH-SY5Y cells (SH-SY5Y-A and SH-SY5Y-E), each of which show a different phenotype during RA-mediated differentiation. Findings SH-SY5Y-A cells differentiated in the presence of RA, whereas RA-treated SH-SY5Y-E cells required additional treatment with brain-derived neurotrophic factor (BDNF) for full differentiation. After exposing cells to a PI3K inhibitor, LY294002, we identified 386 genes and categorised these genes into two clusters dependent on the PI3K signalling pathway during RA-mediated differentiation in SH-SY5Y-A cells. Transcriptional regulation of the gene cluster, including 158 neural genes, was greatly reduced in SK-N-SH cells and partially impaired in SH-SY5Y-E cells, which is consistent with a defect in the neuronal phenotype of these cells. Additional stimulation with BDNF induced a set of neural genes that were down-regulated in RA-treated SH-SY5Y-E cells but were abundant in differentiated SH-SY5Y-A cells. Conclusion We identified gene clusters controlled by PI3K- and TRKB-mediated signalling pathways during the differentiation of two subtypes of SH-SY5Y cells. The TRKB-mediated bypass pathway compensates for impaired neural function generated by defects in several signalling pathways, including PI3K in SH-SY5Y-E cells. Our expression profiling data will be useful for further elucidation of the signal transduction-transcriptional network involving PI3K or TRKB.
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Affiliation(s)
- Yuichiro Nishida
- Computational and Experimental Systems Biology Group, RIKEN Genomic Sciences Centre, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
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Ma W, Tavakoli T, Derby E, Serebryakova Y, Rao MS, Mattson MP. Cell-extracellular matrix interactions regulate neural differentiation of human embryonic stem cells. BMC DEVELOPMENTAL BIOLOGY 2008; 8:90. [PMID: 18808690 PMCID: PMC2570688 DOI: 10.1186/1471-213x-8-90] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 09/22/2008] [Indexed: 12/21/2022]
Abstract
Background Interactions of cells with the extracellular matrix (ECM) are critical for the establishment and maintenance of stem cell self-renewal and differentiation. However, the ECM is a complex mixture of matrix molecules; little is known about the role of ECM components in human embryonic stem cell (hESC) differentiation into neural progenitors and neurons. Results A reproducible protocol was used to generate highly homogenous neural progenitors or a mixed population of neural progenitors and neurons from hESCs. This defined adherent culture system allowed us to examine the effect of ECM molecules on neural differentiation of hESCs. hESC-derived differentiating embryoid bodies were plated on Poly-D-Lysine (PDL), PDL/fibronectin, PDL/laminin, type I collagen and Matrigel, and cultured in neural differentiation medium. We found that the five substrates instructed neural progenitors followed by neuronal differentiation to differing degrees. Glia did not appear until 4 weeks later. Neural progenitor and neuronal generation and neurite outgrowth were significantly greater on laminin and laminin-rich Matrigel substrates than on other 3 substrates. Laminin stimulated hESC-derived neural progenitor expansion and neurite outgrowth in a dose-dependent manner. The laminin-induced neural progenitor expansion was partially blocked by the antibody against integrin α6 or β1 subunit. Conclusion We defined laminin as a key ECM molecule to enhance neural progenitor generation, expansion and differentiation into neurons from hESCs. The cell-laminin interactions involve α6β1 integrin receptors implicating a possible role of laminin/α6β1 integrin signaling in directed neural differentiation of hESCs. Since laminin acts in concert with other ECM molecules in vivo, evaluating cellular responses to the composition of the ECM is essential to clarify further the role of cell-matrix interactions in neural derivation of hESCs.
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Affiliation(s)
- Wu Ma
- Stem Cell Center, Developmental Biology, American Type Culture Collection, Manassas, VA, USA.
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Walton RM, Wolfe JH. In vitro growth and differentiation of canine olfactory bulb-derived neural progenitor cells under variable culture conditions. J Neurosci Methods 2008; 169:158-67. [PMID: 18261803 PMCID: PMC2377027 DOI: 10.1016/j.jneumeth.2007.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Revised: 12/05/2007] [Accepted: 12/05/2007] [Indexed: 10/22/2022]
Abstract
The dog serves as a large animal model for multiple neurologic diseases that may potentially benefit from neural progenitor cell (NPC) transplantation. In the adult brain, multipotent NPCs reside in the subventricular zone and its rostral and caudal extensions into the olfactory bulb and hippocampus. The olfactory bulb represents a surgically accessible site for obtaining cells for autologous NPC transplantation. To model conditions that would occur for ex vivo gene therapy in the postnatal brain, NPCs were isolated from the canine olfactory bulb, expanded ex vivo under different culture conditions, and compared quantitatively for growth and immunophenotype. Under standard growth conditions, canine olfactory bulb-derived NPCs (OB-cNPCs) could be expanded nearly 500-fold in the time evaluated. Canine OB-cNPCs grown on poly-d-lysine (PDL) or on PDL-fibronectin had similar growth rates, whereas supplementation with leukemia inhibitory factor (LIF) resulted in significantly slower growth. However, when OB-cNPC cultures were grown on PDL-fibronectin or PDL supplemented with LIF, a greater proportion of cells with neuronal markers were generated upon differentiation.
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Affiliation(s)
- Raquel M. Walton
- W.F. Goodman Center for Comparative Medical Genetics, School of Veterinary Medicine, University of Pennsylvania; and Stokes Research Institute, Children’s Hospital of Philadelphia, Philadelphia, PA 19104 USA
| | - John H. Wolfe
- W.F. Goodman Center for Comparative Medical Genetics, School of Veterinary Medicine, University of Pennsylvania; and Stokes Research Institute, Children’s Hospital of Philadelphia, Philadelphia, PA 19104 USA
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Hlady V, Hodgkinson G. The effects of proteoglycan surface patterning on neuronal pathfinding. MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK 2007; 38:975. [PMID: 20119506 PMCID: PMC2813059 DOI: 10.1002/mawe.200700224] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Indexed: 05/28/2023]
Abstract
Protein micropatterning techniques are increasingly applied in cell choice assays to investigate fundamental biological phenomena that contribute to the host response to implanted biomaterials, and to explore the effects of protein stability and biological activity on cell behavior for in vitro cell studies. In the area of neuronal regeneration the protein micropatterning and cell choice assays are used to improve our understanding of the mechanisms directing nervous system during development and regenerative failure in the central nervous system (CNS) wound healing environment. In these cell assays, protein micropatterns need to be characterized for protein stability, bioactivity, and spatial distribution and then correlated with observed mammalian cell behavior using appropriate model system for CNS development and repair. This review provides the background on protein micropatterning for cell choice assays and describes some novel patterns that were developed to interrogate neuronal adaptation to inhibitory signals encountered in CNS injuries.
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Affiliation(s)
- V. Hlady
- University of Utah, Salt Lake City, UT 83112, USA
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Walton RM, Wolfe JH. Abnormalities in Neural Progenitor Cells in a Dog Model of Lysosomal Storage Disease. J Neuropathol Exp Neurol 2007; 66:760-9. [PMID: 17882020 DOI: 10.1097/nen.0b013e31812571c8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Lysosomal storage disorders constitute a large group of genetic diseases, many of which are characterized by mental retardation and other neurologic symptoms. The mechanisms of neural dysfunction remain poorly understood. Because neural progenitor cells (NPCs) are fundamentally important to normal brain development and function, we investigated NPC properties in a canine model of mucopolysaccharidosis VII (MPS VII). MPS VII is a lysosomal storage disorder characterized by defects in the catabolism of glycosaminoglycans. NPCs were isolated from the olfactory bulb, cerebellum, and striatal subventricular zone of normal and MPS VII (beta-glucuronidase-deficient) postnatal dog brains. Canine NPCs (cNPCs) from normal and MPS VII brains had similar growth curves, but cerebellar-derived cNPCs grew significantly slower than those derived from other regions. In differentiation assays, MPS VII cNPCs from the striatal subventricular zone and cerebellum generated fewer mature neuronal and/or glial cells than normal, and MPS VII olfactory bulb-derived cNPCs retained significantly more phenotypically immature cells. These differences were only present at the earliest time point after isolation; at later passages, there were no differences attributable to genotype. The data suggest that MPS VII cNPCs respond differently to developmental cues in vivo, probably because of the diseased neural microenvironment rather than intrinsic cellular deficits.
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Affiliation(s)
- Raquel M Walton
- W F Goodman Center for Comparative Medical Genetics, and Department of Pathology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Hodgkinson GN, Tresco PA, Hlady V. The differential influence of colocalized and segregated dual protein signals on neurite outgrowth on surfaces. Biomaterials 2007; 28:2590-602. [PMID: 17316787 PMCID: PMC1892536 DOI: 10.1016/j.biomaterials.2007.01.038] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 01/23/2007] [Indexed: 12/01/2022]
Abstract
We present an in vitro micropatterning approach in which the density and spatial presentation of two separate protein layers can be independently controlled to form cell stripe assays through (1) the simultaneous application of microcontact printing (microCP) and microfluidic network (microFN) patterning to generate alternating stripes of pure single protein layers or (2) through microCP onto a pre-adsorbed homogeneous protein layer to generate alternating single and dual protein stripes. This approach enabled the creation of choice boundaries in which protein-protein interactions were limited and the effects of spatially segregated or colocalized dual protein signals on model primary neuronal behavior could be readily interrogated and compared on both glass and tissue culture polystyrene substrates. Dorsal root ganglion (DRG) cell body attachment was dictated largely by non-specific cell adhesion interactions and interactions between the guidance molecules laminin and aggrecan were insufficient to explain aggrecan inhibition on neurite outgrowth. The presentation of a specific laminin epitope stabilized by interactions with aggrecan and destabilized by microCP was a strong predictor of neurite promoting activity. These observations provide evidence that aggrecan is intrinsically inhibitory and that laminin-aggrecan interactions do not diminish laminin growth promoting properties.
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Affiliation(s)
- Gerald N. Hodgkinson
- Department of Bioengineering, University of Utah, 20 S. 2030 E., Rm. 108, Salt Lake City, Utah 84112
| | - Patrick A. Tresco
- Department of Bioengineering, University of Utah, 20 S. 2030 E., Rm. 108, Salt Lake City, Utah 84112
- Keck Center for Tissue Engineering, University of Utah, 20 S. 2030 E., Rm. 108, Salt Lake City, Utah 84112
| | - Vladimir Hlady
- Department of Bioengineering, University of Utah, 20 S. 2030 E., Rm. 108, Salt Lake City, Utah 84112
- * Corresponding author. Tel.: 801-581-5042; E-mail address:
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Pizzi MA, Crowe MJ. Transplantation of Fibroblasts that Overexpress Matrix Metalloproteinase-3 into the Site of Spinal Cord Injury in Rats. J Neurotrauma 2006; 23:1750-65. [PMID: 17184186 DOI: 10.1089/neu.2006.23.1750] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Growth-inhibitory chondroitin sulfate proteoglycans (CSPGs) are upregulated during glial scar formation at the site of spinal cord injury (SCI) in adult mammals. This CSPG-containing glial scar inhibits axonal regeneration. Matrix metalloproteinases (MMPs) can degrade CSPGs and other inhibitory proteins to promote neurite outgrowth. Increased MMP synthesis and secretion are observed in fibroblasts adjacent to tumor cells that express the protein EMMPRIN (Extracellular Matrix MetalloPRoteinase INducer). EMMPRIN transduction of cells provides an avenue to deliver increased levels of MMPs to the site of SCI in a sustained, localized, and moderate fashion. We explored the use of EMMPRIN-transduced cells as a mechanism to degrade CSPGs, facilitate axonal growth and improve recovery after SCI. Human dermal fibroblasts infected with a recombinant EMMPRIN adenovirus significantly increased secretion of MMP-3 compared to fibroblasts infected with a control adenovirus. Decreased CSPG immunoreactivity was observed in injured spinal cord sections when they were incubated with media from EMMPRIN-transduced fibroblasts. Conditioned media from EMMPRIN-transduced fibroblasts increased the length of neurites that were grown on a CSPG substrate. Rats that received contusive SCI and EMMPRIN-transduced fibroblast transplants demonstrated improved locomotor recovery compared to rats that received control fibroblasts, but not compared to other control groups. EMMPRIN-transplanted rats showed a significant increase in the number of retrogradely labeled cell bodies within brainstem nuclei and an increase in serotonergic fibers distal to the site of injury. EMMPRIN, and consequently MMP, delivery to the injured spinal cord may prove to be beneficial in reducing some of the physical barriers to axonal growth after SCI.
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Affiliation(s)
- Michael A Pizzi
- Department of Cell Biology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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18
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Easley CA, Faison MO, Kirsch TL, Lee JA, Seward ME, Tombes RM. Laminin activates CaMK-II to stabilize nascent embryonic axons. Brain Res 2006; 1092:59-68. [PMID: 16690036 DOI: 10.1016/j.brainres.2006.03.099] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2005] [Revised: 03/21/2006] [Accepted: 03/23/2006] [Indexed: 11/25/2022]
Abstract
In neurons, the interaction of laminin with its receptor, beta1 integrin, is accompanied by an increase in cytosolic Ca2+. Neuronal behavior is influenced by CaMK-II, the type II Ca2+/calmodulin-dependent protein kinase, which is enriched in axons of mouse embryonic neurons. In this study, we sought to determine whether CaMK-II is activated by laminin, and if so, how CaMK-II influences axonal growth and stability. Axons grew up to 200 microm within 1 day of plating P19 embryoid bodies on laminin-1 (EHS laminin). Activated CaMK-II was found enriched along the axon and in the growth cone as detected using a phospho-Thr(287) specific CaMK-II antibody. beta1 integrin was found in a similar pattern along the axon and in the growth cone. Direct inhibition of CaMK-II in 1-day-old neurons immediately froze growth cone dynamics, disorganized F-actin and ultimately led to axon retraction. Collapsed axonal remnants exhibited diminished phospho-CaMK-II levels. Treatment of 1-day neurons with a beta1 integrin-blocking antibody (CD29) also reduced axon length and phospho-CaMK-II levels and, like CaMK-II inhibitors, decreased CaMK-II activation. Among several CaMK-II variants detected in these cultures, the 52-kDa delta variant preferentially associated with actin and beta 3 tubulin as determined by reciprocal immunoprecipitation. Our findings indicate that persistent activation of delta CaMK-II by laminin stabilizes nascent embryonic axons through its influence on the actin cytoskeleton.
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Affiliation(s)
- Charles A Easley
- Department of Biology and Biochemistry, Virginia Commonwealth University, Richmond, VA 23284-2012, USA
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19
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Abstract
An enormous literature has been developed on investigations of the growth and guidance of axons during development and after injury. In this review, we provide a guide to this literature as a resource for biomedical investigators. We first review briefly the molecular biology that is known to regulate migration of the growth cone and branching of axonal arbors. We then outline some important fundamental considerations that are important to the modeling of the phenomenology of these guidance effects and of what is known of their underlying internal mechanisms. We conclude by providing some thoughts on the outlook for future biomedical modeling in the field.
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Affiliation(s)
- Susan Maskery
- Biomedical Informatics, Windber Research Institute, Windber, PA 15963, USA.
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20
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Jiang Z, Yu PH. Involvement of extracellular signal-regulated kinases 1/2 and (phosphoinositide 3-kinase)/Akt signal pathways in acquired resistance against neurotoxin of 6-hydroxydopamine in SH-SY5Y cells following cell-cell interaction with astrocytes. Neuroscience 2005; 133:405-11. [PMID: 15878643 DOI: 10.1016/j.neuroscience.2005.02.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Revised: 01/27/2005] [Accepted: 02/20/2005] [Indexed: 11/21/2022]
Abstract
Glial cells interact with neurons and play important roles in the development, differentiation, maintenance and repair of the nervous system. Human neuroblastoma cells (SH-SY5Y) became dramatically resistant to neurotoxin 6-hydroxydopamine (6-OHDA), when co-cultured with mouse astrocytes. In order to further delineate the molecular mechanism involved in the neuroprotection in this selective cell-cell interaction, we assessed the activation of two signal pathways, namely, the MAP kinases (extracellular signal-regulated kinases, ERK1/2) and phosphoinositide 3-kinase (PI3-K)/Akt signal pathways in response to 6-OHDA insult and subsequent neuronal survival. Western blot revealed that 6-OHDA significantly increased the phosphorylation of ERK1/2 and Akt in mono-cultured SH-SY5Y cells. However, the increase in ERK1/2 in SH-SY5Y cells after co-cultured with astrocytes occurred as early as 3 h after 6-OHDA treatment in oppose to the increase after 12 h in monocultures. The phosphorylation of Akt in the co-cultured SH-SY5Y cells was much pronounced 3 h after 6-OHDA treatment compared with that in the mono-cultured cells. The anti-apoptotic protein bcl-2 was also increased in the co-cultured SH-SY5Y cells 3 h after treatment with 6-OHDA. Selective inhibitor of PI3-K/Akt signal pathway blocked the acquired resistance to 6-OHDA in SH-SY5Y cells following interaction with astrocytes. Inhibition of ERK1/2 signal pathway did not affect the cell survival. Our data suggest that PI3-K/Akt signal pathway, but not ERK1/2, is involved the acquired resistance in SH-SY5Y cells following cell-cell interaction with astrocytes against the neurotoxic 6-OHDA insult.
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Affiliation(s)
- Z Jiang
- Neuropsychiatry Research Unit, Department of Psychiatry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E4
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21
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Lent R, Uziel D, Baudrimont M, Fallet C. Cellular and molecular tunnels surrounding the forebrain commissures of human fetuses. J Comp Neurol 2005; 483:375-82. [PMID: 15700272 DOI: 10.1002/cne.20427] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Glial cells and extracellular matrix (ECM) molecules surround developing fiber tracts and are implicated in axonal pathfinding. These and other molecules are produced by these strategically located glial cells and have been shown to influence axonal growth across the midline in rodents. We searched for similar cellular and molecular structures surrounding the telencephalic commissures of fetal human brains. Paraffin-embedded brain sections were immunostained for glial fibrillary acidic protein (GFAP) and vimentin (VN) to identify glial cells; for microtubule-associated protein-2 (MAP-2) and neuronal nuclear protein (NeuN) to document neurons; for neurofilament (NF) to identify axons; and for chondroitin sulfate (CS), tenascin (TN), and fibronectin (FN) to show the ECM. As in rodents, three cellular clusters surrounding the corpus callosum were identified by their expression of GFAP and VN (but not MAP-2 or NeuN) from 13 to at least 18 weeks postovulation (wpo): the glial wedge, the glia of the indusium griseum, and the midline sling. CS and TN (but not FN) were expressed pericellularly in these cell groups. The anterior commissure was surrounded by a GFAP+/VN+ glial tunnel from 12 wpo, with TN expression seen between the GFAP+ cell bodies. The fimbria showed GFAP+/VN+ cells at its lateral and medial borders from 12 wpo, with pericellular expression of CS. The fornix showed GFAP+ cells somewhat later (16 wpo). Because these structures are similar to those described for rodents, we concluded that the axon guiding mechanisms postulated for commissural formation in nonhuman mammals may also be operant in the developing human brain.
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Affiliation(s)
- Roberto Lent
- Departamento de Anatomia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil.
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22
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Yagi T, Terada N, Baba T, Ohno S. Immunolocalization of laminin-alpha1-like antigens around synapses in mouse cerebellar perineuronal nets. ACTA ACUST UNITED AC 2004; 34:559-65. [PMID: 14626346 DOI: 10.1023/a:1026044517888] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The hypothesis that extracellular matrix components may be related to neuronal development in the mouse cerebellar cortex was verified with immunohistochemistry by using an antibody against laminin-alpha1, a major extracellular matrix protein in various tissues. A commercially available polyclonal antibody, raised against the carboxyl-terminal 20-amino acid peptide of laminin-alpha1 was used. Some positive immunoreaction products were localized around large GABAergic interneurons in granular layers and others were around neurons in deep cerebellar nuclei. At the electron microscope level, diaminobenzidine immunoreaction products were localized around presynaptic boutons and in intercellular matrices around interneurons. Such immunoreaction products could be detected at postnatal day 20, when most of cerebellar synapses are assumed to be established. It has been known that a special feature of extracellular matrix, termed perineuronal nets, exists around specific subpopulation of neurons. In the mouse cerebellum, the present findings suggest that laminin itself or laminin-like-antigens exists in the perineuronal nets in relation to inhibitory neuron synapses.
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Affiliation(s)
- Takashi Yagi
- Department of Anatomy, Faculty of Medicine, University of Yamanashi, Tamaho, Yamanashi 409-3898, Japan
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Hynds DL, Spencer ML, Andres DA, Snow DM. Rit promotes MEK-independent neurite branching in human neuroblastoma cells. J Cell Sci 2003; 116:1925-35. [PMID: 12668729 DOI: 10.1242/jcs.00401] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rit, by sequence homology, is a member of the Ras subfamily of small guanine triphosphatases (GTPases). In PC6 cells, Rit signals through pathways both common to and different from those activated by Ras to promote cell survival and neurite outgrowth. However, the specific morphological changes induced by Rit in human cells are not known. Here, we show in a human neuronal model that Rit increases neurite outgrowth and branching through MEK-dependent and MEK-independent signaling mechanisms, respectively. Adenoviral expression of wild-type or constitutively active Rit increased neurite initiation, elongation and branching on endogenous matrix or a purified laminin-1 substratum of SH-SY5Y cells as assessed using image analysis. This outgrowth was morphologically distinct from that promoted by constitutively active Ras or Raf (evidenced by increased branching and elongation). Constitutively active Rit increased phosphorylation of ERK 1/2, but not Akt, and the MEK inhibitor PD 098059 blocked constitutively active Rit-induced neurite initiation but not elongation or branching. These results suggest that Rit plays a key role in human neuronal development and regeneration through activating both known and as yet undefined signaling pathways.
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Affiliation(s)
- DiAnna L Hynds
- Department of Anatomy and Neurobiology, University of Kentucky Medical Center, Lexington, KY 40536-0298, USA.
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24
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Chafik D, Bear D, Bui P, Patel A, Jones NF, Kim BT, Hung CT, Gupta R. Optimization of Schwann cell adhesion in response to shear stress in an in vitro model for peripheral nerve tissue engineering. TISSUE ENGINEERING 2003; 9:233-41. [PMID: 12740086 DOI: 10.1089/107632703764664701] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The design of nerve guidance channels (NGCs) is evolving to produce a favorable environment for neural regeneration. We created an in vitro model to evaluate the interactions between three centrally important components of this altered host environment: (1). Schwann cells, (2). substrate, and (3). sustained mechanical stimulus in the form of shear stress with laminar fluid flow. Preconfluent Schwann cells were plated on slides coated either with laminin, poly-D-lysine, type IV collagen, or fibronectin. These slides were placed into custom-designed, parallel-plate, flow chambers and were administered laminar fluid flow at a rate of 15 mL/min for 2 h. Schwann cell adhesion assays demonstrated that laminin (mean, 86.1%; SEM, 4.47%) and fibronectin (mean, 81.7%; SEM, 3.24%) were statistically superior to collagen type IV (mean, 57.7%; SEM, 3.96%) and poly-D-lysine (mean, 58.0%; SEM, 4.97%) (p < 0.001). Fibronectin (mean, 12.20%; SEM, 0.374%) induced statistically greater Schwann cell proliferation than did laminin (mean, 8.14%; SEM, 0.682%) (p < 0.001). Therefore, we recommend that fibronectin should be used as an important component of NGCs with further in vivo studies. As mechanical stress is an integral part of the host environment, our study is the first to incorporate this factor into an in vitro model for peripheral nerve tissue engineering.
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Affiliation(s)
- Dara Chafik
- Department of Orthopedic Surgery, University of California, Irvine, Irvine, California 92657, USA
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25
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Braga-de-Souza S, Lent R. Temporal and spatial regulation of chondroitin sulfate, radial glial cells, growing commissural axons, and other hippocampal efferents in developing hamsters. J Comp Neurol 2003; 468:217-32. [PMID: 14648681 DOI: 10.1002/cne.10947] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We investigated the time and space relationship between growth of hippocampal efferents, particularly those forming the hippocampal commissure, and expression of extracellular matrix components related to radial glial cells. Developing hamster brains from embryonic day (E) 13 to postnatal day (P) 7 had 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) crystals implanted into the hippocampus or were processed for fluorescent immunohistochemistry against chondroitin sulfate (CS) glycosaminoglycans and glial fibrillary acidic protein (GFAP). The first, pioneer fibers from the hippocampus were seen crossing the midline at E15 and arriving at the contralateral hippocampus 24-48 hours later (P1), followed closely by a thick front of growing fibers. Before E15, CS expression was preceded by septal fusion and was concomitant with formation of the commissural tract. On E15, CS expression formed a U-shaped border below the fimbria. From E15 to P3, CS became expressed between the hippocampal commissure and the third ventricle and at the caudal borders of the fornix columns. As the hippocampal commissure expanded, CS expression became gradually lighter to virtually disappear by P7. On E15 and P1, GFAP-positive radial glial cells were present caudal (but not rostral) to the commissure at the midline, partially overlapping CS expression. Similar cells were present dorsal to the fimbria, extending their processes perpendicularly over the growing axons. The data reveal that CS and radial glial cells form a tunnel surrounding the developing fimbria and a border at the midline caudal to the hippocampal commissure. It is suggested that these cellular and molecular borders play a role in guidance of hippocampal efferents.
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Affiliation(s)
- Suzana Braga-de-Souza
- Departamento de Anatomia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil
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26
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Hynds DL, Takehana A, Inokuchi J, Snow DM. L- and D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) inhibit neurite outgrowth from SH-SY5Y cells. Neuroscience 2002; 114:731-44. [PMID: 12220574 DOI: 10.1016/s0306-4522(02)00302-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Gangliosides and extracellular matrix molecules influence neurite outgrowth, but the combinatorial effects of these endogenous agents on outgrowth are unclear. Exogenous gangliosides inhibit neurite outgrowth from SH-SY5Y cells stimulated with platelet-derived growth factor-BB, and different isoforms of the ceramide analog threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) stimulate (L-PDMP) or inhibit (D-PDMP) glycosphingolipid biosynthesis. In this study, we determined whether altering the endogenous ganglioside levels with PDMP in SH-SY5Y cells regulates neurite outgrowth on the outgrowth-supporting extracellular matrix molecule, laminin. In cells stimulated with 20 ng/ml platelet-derived growth factor-BB to promote outgrowth, we used image analysis to evaluate neurite outgrowth from SH-SY5Y cells grown on endogenous matrix or laminin and exposed to L- or D-PDMP. Both L- and D-PDMP decreased neurite initiation (the number of neurites/cell, the percent of neurite-bearing cells), elongation (the length of the longest neurite/cell, the total neurite length/cell), and branching (the number of branch points/neurite) from SH-SY5Y cells on endogenous matrix or laminin in a dose-dependent manner in serum-free or serum-containing medium. The inhibitory effects of each PDMP isoform were reversible. Inhibition of neurite outgrowth by L-PDMP could be mimicked by addition of exogenous gangliosides or C2-ceramide. Our analyses of neurite outgrowth in SH-SY5Y cells, a model of developing or regenerating noradrenergic neurons, demonstrate that increasing or decreasing endogenous ganglioside levels decreases neurite outgrowth. These results may indicate that SH-SY5Y cells undergo tight regulation by gangliosides, possibly through modulation of growth/trophic factor- and/or extracellular matrix-activated signaling cascades.
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Affiliation(s)
- D L Hynds
- Anatomy and Neurobiology, University of Kentucky, MN232/234 UKMC, 800 Rose Street, Lexington, KY 40536-0298, USA.
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Hynds DL, Snow DM. A semi-automated image analysis method to quantify neurite preference/axon guidance on a patterned substratum. J Neurosci Methods 2002; 121:53-64. [PMID: 12393161 DOI: 10.1016/s0165-0270(02)00231-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Axon outgrowth and guidance are differentially promoted or inhibited by specific extracellular matrix (ECM) molecules. The effects of these molecules can be examined by culturing neuronal explants on patterned substrata consisting of alternating stripes adsorbed with the molecules of interest. While outgrowth on substrata adsorbed with homogenous molecules can be reliably quantified, current methods of quantifying neurite preference on patterned substrata are subjective, labor intensive, and overall less reliable. Here, we present a quick, semi-automated, lowly subjective macro-based method to quantify the effects of a change in substratum on axon extension and guidance. We plated chick dorsal root ganglion explants on a substratum consisting of alternating stripes of laminin-1 (outgrowth supportive) and chondroitin sulfate proteoglycans (CSPGs, outgrowth inhibitory). We evaluated neurite preference for laminin or CSPG-coated regions by measuring total neurite area, and produced an inhibition index. The quantitative data confirmed previous qualitative data showing that increasing concentrations of CSPGs induced increases in inhibition. The methods presented here: (1) require less stringent image capture criteria; (2) are quicker; (3) are less subjective compared to previously described methods; and (4) are versatile in that they can be used to assay neurite preference for any substratum-bound molecules in living or fixed cultures.
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Affiliation(s)
- DiAnna L Hynds
- Department of Anatomy and Neurobiology, University of Kentucky, MN 238 UKMC, 800 Rose Street, Lexington, KY 40536-0298, USA.
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Chen ZJ, Ughrin Y, Levine JM. Inhibition of axon growth by oligodendrocyte precursor cells. Mol Cell Neurosci 2002; 20:125-39. [PMID: 12056844 DOI: 10.1006/mcne.2002.1102] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The glial scar that forms at the site of injury is thought to be a biochemical and physical barrier to successful regeneration, although the molecules responsible for this barrier function are not well understood. Glia scars contain large numbers of oligodendrocyte precursor cells (OPCs) and these cells can produce several different growth-inhibitory chondroitin sulfate proteoglycans (CSPGs), including NG2, neurocan, and phosphacan. Here, we used membrane-based assays to show that the surface of OPCs is both nonpermissive and inhibitory for neurite outgrowth. Inhibition of growth by OPC is reversed by treatment with antibodies against the NG2 CSPG and the expression of NG2 is sufficient to change a growth-permissive cell surface to a nonpermissive surface. These result suggest that the OPCs that accumulate rapidly at sites of CNS injury can contribute to the creation of an environment that inhibits nerve regeneration and that NG2 is a necessary feature of that environment.
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Affiliation(s)
- Zhi Jiang Chen
- Department of Neurobiology and Behavior, SUNY at Stony Brook, New York 11794, USA
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