Focal adhesion kinase regulation in stem cell alignment and spreading on nanofibers

Abstract

While electrospun nanofibers have demonstrated the potential for novel tissue engineering scaffolds, very little is known about the molecular mechanism of how cells sense and adapt to nanofibers. Here, we revealed the role of focal adhesion kinase (FAK), one of the key molecular sensors in the focal adhesion complex, in regulating mesenchymal stem cell (MSC) shaping on nanofibers. We produced uniaxially aligned and randomly distributed nanofibers from poly(L-lactic acid) to have the same diameters (about 130 nm) and evaluated MSC behavior on these nanofibers comparing with that on flat PLLA control. C3H10T1/2 murine MSCs exhibited upregulations in FAK expression and phosphorylation (pY397) on nanofibrous cultures as assessed by immunoblotting, and this trend was even greater on aligned nanofibers. MSCs showed significantly elongated and well-spread morphologies on aligned and random nanofibers, respectively. In the presence of FAK silencing via small hairpin RNA (shRNA), cell elongation length in the aligned nanofiber direction (cell major axis length) was significantly decreased, while cells still showed preferred orientation along the aligned nanofibers. On random nanofibers, MSCs with FAK-shRNA showed impaired cell spreading resulting in smaller cell area and higher circularity. Our study provides new data on how MSCs shape their morphologies on aligned and random nanofibrous cultures potentially via FAK-mediated mechanism.

Nanostructured TiO2 Surfaces Promote Human Bone Marrow Mesenchymal Stem Cells Differentiation to Osteoblasts

“…The evaluation of p-FAK foci indicates unequivocally cellular behavior in response to different matrices [33,34]. In our study, TiO 2 nanostructured surface promoted in a short time (24 h) the amount of hBMSCs pFAK foci with respect to common Glass (Figure 2).…”

Influence of the nanofiber chemistry and orientation of biodegradable poly(butylene succinate)-based scaffolds on osteoblast differentiation for bone tissue regeneration

“…Furthermore, cells preferentially adhered on nanofibers and their orientation was shown to be influenced by fiber alignment. [27][28][29] To quantitatively evaluate cell attachment, SAOS-2 cells seeded on the different mats and the control (TCPS) were incubated for 24 h, and the activation of signalling molecules such as FAK and phosphorylated FAK ( pY397) was evaluated ( Fig. 5B and C).…”

Lineage‐Specific Commitment of Stem Cells with Organic and Graphene Oxide–Functionalized Nanofibers

“…Indeed, surface cues are to be captured by cell surface receptors, leading to integrin conformational changes, and then regulating differentiation‐related signal transduction mechanisms such as focal adhesion kinase recruitment, phosphorylation, and subsequent signaling. A recent report has evidenced the possible upregulation of such mechanisms for SCs on aligned nanofibers, and the decrease of cell elongation along the fiber direction upon focal adhesion kinase silencing through small hairpin RNA . Evaluating the cell anisotropy in terms of the stretching‐induced elongation, namely, the short/long cell axis ratio (AR, Figure f) and the corresponding nuclear circularity (Figure g), therefore elucidates the signaling paths to differentiation.…”