Biomedical Engineering Reference
In-Depth Information
- Brain (aligned neurite connecting cerebral
cortex and ventricular surface)
- Skeletal muscle (aligned muscle fibers)
- Heart (aligned myocardial muscle fibers)
- Skin (organized ECM matrix
fibers in dermis)
- Vesssel (nanofibrous matrices
in basal lamina)
- Bone (brick-and-mortar like structure in cortical
bone)
- Ligament (aligned and hierarchical collagen fiber
bundles)
- Tendon (aligned and hierarchical collagen fiber
bundles)
Figure 15.2
Different nanotopographical forms in various human tissues [82].
To study the effect of different topographies and mimic the anisotropic structures of
neural cells, techniques such as electrospinning and nanolithography have been used to
design a number of micro-/nanostructures in the form of fibers or gratings [82, 83]. The
behavior of nerve cells in the context of differentiation, neurite outgrowth, attachment,
migration, and alignment has been investigated on these micro-/nanostructures.
Microgrooved substrates guide the development, differentiation, and neurite extension
of human NSCs related to the microchannel width. Small patterns not only induce proper
neurite alignment but also induce longer neurite length, whereas larger micropatterns have
been shown to hinder alignment [84]. Another study has researched the alignment and
elongation of human pluripotent stem cells (hPSCs) along the micron-sized grating axis.
While the cells exhibited random morphology on the unpatterned substrate, filopodia
aligned greatly with the introduction of 2 μm gratings and neural markers highly expressed
on this surface (Figure 15.3) [85].
Previously, it has been shown that by using 350 nm ridge/groove topographic surfaces,
human ESCs (hESCs) could be differentiated to neurons without the introduction of
chemical factors [86]. Recently, the effect of polydimethylsiloxane (PDMS) nanograting
substrates with various widths on growth and differentiation of human-induced pluripotent
stem cells (hiPSCs) showed that cellular contact-guidance enhanced considerably on the
smaller pitch. The expression of neural markers significantly upregulated on grating with a
width of 350 nm compared to the flat surface [87].
