Extracellular matrix and biomimetic engineering microenvironment for neuronal differentiation

Abstract

Extracellular matrix (ECM) influences cell differentiation through its structural and biochemical properties. In nervous system, neuronal behavior is influenced by these ECMs structures which are present in a meshwork, fibrous, or tubular forms encompassing specific molecular compositions. In addition to contact guidance, ECM composition and structures also exert its effect on neuronal differentiation. This short report reviewed the native ECM structure and composition in central nervous system and peripheral nervous system, and their impact on neural regeneration and neuronal differentiation. Using topographies, stem cells have been differentiated to neurons. Further, focussing on engineered biomimicking topographies, we highlighted the role of anisotropic topographies in stem cell differentiation to neurons and its recent temporal application for efficient neuronal differentiation.

Keywords: biomimetic platforms; biophysical cues; contact guidance; extracellular matrix; neural regeneration; neural stem cell niche; neuronal development; neuronal differentiation; neuronal maturation; stem cell; topography.

Figure 1

Nervous system components architecture. (A) Schematic diagram of brain extracellular matrix (ECM) components and their architecture. (B) Schematic diagram of peripheral nerve cross-section and the collagen fibers.

Figure 2

Human pluripotent stem cell (hPSC) colonies and hPSC elongate along the grating axis of 2 μm gratings. (A) 2 μm gratings are reproduced with high fidelity, as demonstrated by scanning electron microscope. PSC cultured on the unpatterned control. (B) hPSC cultured on the unpatterned control exhibited a spread morphology in contrast to the elongated morphology observed on 2 μm gratings. Cells were stained for phalloidin (green) and 4′,6-diamidino-2-phenylindole (blue). Scale bars: 5 μm (left) and 200 μm (right). (C) The filopodia of hPSC on 2 μm gratings extend along, across and between gratings (white arrows). Adapted from Chan et al. (2013).

Figure 3

Morphology of tyrosine hydroxylase-positive (TH) neurons on patterned and unpatterned substrates after 21 days of differentiation. (A) Representative images of human induced pluripotent stem cell (iPSC)-derived TH neurons on unpatterned, gratings and pillared PDMS substrates. Images were digitally stitched from overlapping fields of view to capture the entire length of neurites. Cells on gratings were aligned on the gratings axis (arrows). Scale bars: 100 μm. (B) Average neurite length per neuron. TH neurons were more elongated when differentiated on gratings than pillars and unpatterned control. (C) Number of terminals per neuron. (D) Number of branch points per neuron. (E) Sholl analysis. TH neurons have significantly more branching and increased neuronal complexity when differentiated on pillars than gratings and unpatterned control. All data are represented as the mean ± SEM of three independent experiments with over 30 TH-positive neurons analyzed on each pattern. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Adapted from Tan et al. (2018).