In VitroRegulation of Neural Differentiation and Axon Growth by Growth Factors and Bioactive Nanofibers

Abstract

Human embryonic stem cell (ESC)-derived neural cells are a potential cell source for neural tissue regeneration. Understanding the biochemical and biophysical regulation of neural differentiation and axon growth will help us develop cell therapies and bioactive scaffolds. We demonstrated that basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) had different effects on human ESC differentiation into neural cells. EGF was more effective in inducing expression of neuron and glial markers and cell extensions. In addition to biochemical cues, poly(l-lactic acid) scaffolds with aligned nanofibers increased axon growth from ESC-derived neural cells, demonstrating the significant effects of biophysical guidance at nanoscale. To combine the biochemical and biophysical cues, bFGF and EGF were either adsorbed or bound to heparin on nanofibrous scaffolds. EGF, but not bFGF, was effectively adsorbed onto nanofibers. However, adsorbed EGF and bFGF did not effectively enhance axon growth. In contrast, immobilization of bFGF or EGF onto nanofibers using heparin as the adapter molecule significantly promoted axon growth. This study elucidated the effect of bFGF and EGF in neural differentiation and axon growth, and demonstrated a method to immobilize active bFGF and EGF onto aligned nanofibers to promote neural tissue regeneration.

Polymeric Nanofibers in Tissue Engineering

“…However, immobilization with a heparin linkage had high efficiency with both bFGF and EGF, and both growth factors appeared to maintain bioactivity. 82 Further, immobilization of growth factors can lead to a different signaling effect compared to a soluble form of the same factor, as the immobilization can reduce the endocytosis of growth factor receptors. 12 Human EGF chemically conjugated to the surface of nanofibers electrospun from copolymer PCL-PEG/PCL was found to be an effective tool in the treatment for diabetic ulcers.…”

“…113 hESCs cultured on aligned PLLA nanofibers displayed enhanced axon growth compared to those cultured on randomly oriented fibers. 82 Further, the diameter of fibers has been shown to influence neural stem cell behavior, as smaller diameter fibers were shown to increase the rates of proliferation and differentiation. 24,114 The conductivity of nanofibers can also be controlled, and conductive nanofibrous scaffolds with average fiber diameters ranging from 112 to 189 nm were electrospun from polyaniline, PCL, and gelatin.…”

“…Immobilizing EGF and bFGF onto the surface of PLLA fibers was shown to significantly enhance the axon growth. 82 …”

Prenatal repair of myelomeningocele with aligned nanofibrous scaffolds—a pilot study in sheep

“…They can supply the appropriate biologic cues to facilitate migration, attachment, proliferation, and differentiation into specific cell phenotypes. Furthermore, through the process of electrospinning, they can be aligned to provide directionality to cellular growth [4][5][6]. The aim of this pilot study was to evaluate the practicality and safety of using aligned biodegradable NS as a regenerative device in the sheep model of prenatal MMC.…”

Embryonic Stem Cells Maintain an Undifferentiated State on Dendrimer-Immobilized Surface with d-Glucose Display

“…So far, many researchers have paid attention to stimulation of receptors on the cytoplasmic membrane of ES cells through interactions with solid surfaces. For example, culture surfaces that can enhance cellular functions, such as ES cell growth, migration and differentiation, have been achieved through the incorporation of tethered adhesive ligands including growth factors and cytokines [10][11][12][13].…”