The impact of laminin on 3D neurite extension in collagen gels

Abstract

The primary goal of this research was to characterize the effect of laminin on three-dimensional (3D) neurite growth. Gels were formed using type I collagen at concentrations of 0.4-2.0 mg mL(-1) supplemented with laminin at concentrations of 0, 1, 10, or 100 µg mL(-1). When imaged with confocal microscopy, laminin was shown to follow the collagen fibers; however, the addition of laminin had minimal effect on the stiffness of the scaffolds at any concentration of collagen. Individual neurons dissociated from E9 chick dorsal root ganglia were cultured in the gels for 24 h, and neurite lengths were measured. For collagen gels without laminin, a typical bimodal response of neurite outgrowth was observed, with increased growth at lower concentrations of collagen gel. However, alteration of the chemical nature of the collagen gel by the laminin additive shifted, or completely mitigated, the bimodal neurite growth response seen in gels without laminin. Expression of integrin subunits, α1, α3, α6 and β1, were confirmed by PCR and immunolabeling in the 3D scaffolds. These results provide insight into the interplay between mechanical and chemical environment to support neurite outgrowth in 3D. Understanding the relative impact of environmental factors on 3D nerve growth may improve biomaterial design for nerve cell regeneration.

The influence of extracellular matrix composition on the differentiation of neuronal subtypes in tissue engineered innervated intestinal smooth muscle sheets

“…The addition of laminin did not alter the ultrastructure, because it was expected to coat collagen fibers evenly. Additionally, laminin was also not expected to alter the stiffness/viscoelasticity of the gels, given the manner of its interaction with the collagens [46-48]. The glycosaminoglycan chains of heparan sulfate are documented to cross link between laminin and collagen IV, thereby pulling fibers into a more compact structure, and slightly increasing the viscoelasticity of ECM gels [45, 49].…”

The effects of confinement on neuronal growth cone morphology and velocity

“…The most parsimonious explanation is that there exists a feedback mechanism that maintains the overall elongation rate. There are a wide range of factors that can modulate axon growth rate, for example laminin concentration [30,31]. While larger growth cones might sense more laminin, smaller growth cones might compensate with an alteration in integrin expression to sustain a necessary growth rate, as neurons have been shown to vary their expression levels of integrins based on laminin concentration in the substrate [32].…”

New View on Endothelial Cell Migration

“…6,32 Functionally, blocking several types of integrins showed that integrins that predominantly bind to laminin were responsible for maintaining the elongated phenotype in Matrigel. This finding is strengthened by the fact that supplementing collagen gels with laminin (in concentrations that were shown to have no influence on the stiffness of the hydrogel 33 ) led to a switch from the blebbing phenotype to the elongated phenotype. Thus, laminin, and not adhesion per se or matrix topography, seems to be crucial in this regard.…”