Neurite extension and neuronal differentiation of human induced pluripotent stem cell derived neural stem cells on polyethylene glycol hydrogels containing a continuous Young's Modulus gradient

Abstract

Mechanotransduction in neural cells involves multiple signaling pathways that are not fully understood. Differences in lineage and maturation state are suggested causes for conflicting reports on neural cell mechanosensitivity. To optimize matrices for use in stem cell therapy treatments transplanting human induced pluripotent stem cell derived neural stem cells (hNSC) into lesions after spinal cord injury, the effects of Young's Modulus changes on hNSC behavior must be understood. The present study utilizes polyethylene glycol hydrogels containing a continuous gradient in Young's modulus to examine changes in the Young's Modulus of the culture substrate on hNSC neurite extension and neural differentiation. Changes in the Young's Modulus of the polyethylene glycol hydrogels was found to affect neurite extension and cellular organization on the matrices. hNSC cultured on 907 Pa hydrogels were found to extend longer neurites than hNSC cultured on other tested Young's Moduli hydrogels. The gene expression of β tubulin III and microtubule-associated protein 2 in hNSC was affected by changes in the Young's Modulus of the hydrogel. The combinatory method approach used in the present study demonstrates that hNSC are mechanosensitive and the matrix Young's Modulus should be a design consideration for hNSC transplant applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 824-833, 2017.

Substrate stiffness affects the morphology and gene expression of epidermal neural crest stem cells in a short term culture

“…In this study, both microscopic observation and FDA staining approved that the stem cells on <1 kPa substrate extended several dendrite-like processes with filopodiaenriched morphology and formed interconnected network structures. This result is in line with the findings of numerous studies which reported that the soft substrate can enhance neuritogenesis (Cangellaris & Gillette, 2018;Mosley et al, 2017) and it has been suggested that filamentous actin (F-actin) is the key factor in neuritogenesis whose organization is strongly regulated by substrate stiffness (Tanaka, Fujii, Kasai, Okajima, & Nakashima, 2018). In addition, our microscopic observations revealed that due to fast attachment of the cells to the softest surface, the mean cell area was higher compared to the CTRL group in the first hours of culture, but as cells attached to the stiff cell culture plate surface by 24 hr, they spread further and showed higher cell surface area compared to the soft one.…”

Biomaterials for Enhancing Neuronal Repair

“…Such measurements of human brain tissue are highly dependent on frequency and region, and therefore variable. Additional studies have demonstrated that timing and duration of exposure to stiffness cues impacts stem cell differentiation to neural cell types, and that while neuritogenesis may be enhanced on soft substrates, network connectivity and signal transduction are enhanced by stiffer substrates (Balgude et al, 2001;Jiang et al, 2010;Keung et al, 2012;Zhang et al, 2014;Mosley et al, 2017). These findings emphasize that stiffness cues should be adjusted depending on the desired outcome, with close attention to the region of interest in the human body.…”

“…b Electrical References: (Jaffe and Stern, 1979;Patel and Poo, 1982;Hotary and Robinson, 1991;Davenport and McCaig, 1993;Metcalf and Borgens, 1994;Yao et al, 2008Yao et al, , 2009Yao et al, , 2011Graves et al, 2011;Koppes et al, 2014;Kim et al, 2016;Ma et al, 2016). c Mechanical Stiffness References: (Balgude et al, 2001;Discher et al, 2005;Jiang et al, 2010;Keung et al, 2012;Lee et al, 2013;Zhang et al, 2014;Mosley et al, 2017).…”

Materials for Neural Differentiation, Trans‐Differentiation, and Modeling of Neurological Disease

“…Hydrogels can be formed with different stiffness, which is one of the important parameters that affect neural differentiation. Polyethylene glycol (PEG) hydrogel was used to determine the effects of Young's modulus on neurite extension and the neural differentiation of hNSC in Mosley et al Research has investigated the effects of changes in Young's modulus (a measure of the stiffness of a solid material) on human iPSCs‐derived NSC behavior. Recently, a more systematic study reported that the PEG hydrogels that contained a continuous gradient in Young's modulus were used to examine changes in the Young's modulus of the culture substrate on neurite extension and neural differentiation.…”