Oriented, Multimeric Biointerfaces of the L1 Cell Adhesion Molecule: An Approach to Enhance Neuronal and Neural Stem Cell Functions on 2-D and 3-D Polymer Substrates

Abstract

This article focuses on elucidating the key presentation features of neurotrophic ligands at polymer interfaces. Different biointerfacial configurations of the human neural cell adhesion molecule L1 were established on two-dimensional films and three-dimensional fibrous scaffolds of synthetic tyrosine-derived polycarbonate polymers and probed for surface concentrations, microscale organization, and effects on cultured primary neurons and neural stem cells. Underlying polymer substrates were modified with varying combinations of protein A and poly-d-lysine to modulate the immobilization and presentation of the Fc fusion fragment of the extracellular domain of L1 (L1-Fc). When presented as an oriented and multimeric configuration from protein A-pretreated polymers, L1-Fc significantly increased neurite outgrowth of rodent spinal cord neurons and cerebellar neurons as early as 24 h compared to the traditional presentation via adsorption onto surfaces treated with poly-d-lysine. Cultures of human neural progenitor cells screened on the L1-Fc/polymer biointerfaces showed significantly enhanced neuronal differentiation and neuritogenesis on all protein A oriented substrates. Notably, the highest degree of βIII-tubulin expression for cells in 3-D fibrous scaffolds were observed in protein A oriented substrates with PDL pretreatment, suggesting combined effects of cell attachment to polycationic charged substrates with subcellular topography along with L1-mediated adhesion mediating neuronal differentiation. Together, these findings highlight the promise of displays of multimeric neural adhesion ligands via biointerfacially engineered substrates to “cooperatively” enhance neuronal phenotypes on polymers of relevance to tissue engineering.

Generation and transplantation of reprogrammed human neurons in the brain using 3D microtopographic scaffolds

“…While the enhanced MAP2 expression in iN cells in thick fibre substrates is consistent with previously reported results 18 29 30 31 , the concurrent increase in excitability indicates active both phenotypic and functional maturation. We propose that the thick fibre substrates drive iN confinement 24 , leading to accelerated maturation due to increased engagement of neural cell-adhesion molecules such as L1 or N-cadherin, which have known roles in neural development 32 33 34 and neuritogenesis 29 31 . In contrast, the thin fibre substrates fail to support neuronal infiltration and aggregation, resulting in the diminished excitability relative to more 3D, thick fibre substrates.…”

Carbon Nanotube Composites as Multifunctional Substrates for In Situ Actuation of Differentiation of Human Neural Stem Cells

“…Electrospun fibrous substrates with controlled fiber architectures provide topographical cues to cells by presenting 3‐D geometries that are representative of the extracellular matrix (ECM), defined by a high surface‐to‐volume ratio and porosity, and are thus better suited for differentiation studies of neural stem cells than standard 2‐D substrates. The architecture of ECM is of special importance because it supports 3‐D cellular networks together to form a tissue, allows for the proliferation and growth of cells, and regulates cellular processes capable of enhancing neurite outgrowth and neuronal differentiation of several cell types, including embryonic stem cells and hESC‐derived NSCs . Furthermore the inherently high surface to volume ratio of electrospun polymer substrates can facilitate mass transfer of nutrients and waste, promote cell attachment, and enable drug loading, properties that are inherent to bioactive matrix microniches.…”

Molecular targeting of TRF2 suppresses the growth and tumorigenesis of glioblastoma stem cells

“…Moreover, knockdown of L1CAM levels can sensitize GSC to radiation (Cheng et al, ). On the other hand, L1CAM is upregulated upon differentiation of neural stem cells into neurons and overexpression of L1CAM can enhance neuronal differentiation and axon growth (Cherry et al, ; Cui et al, ). Future studies will be required to determine whether L1CAM enhances or antagonizes the inhibitory effects of TRF2 depletion on GSC growth and survival.…”