We have recently developed an electrostretching method to generate hydrogel microfibers using aqueous solutions of natural polymers (Zhang, et al, 2014).  This method induces internal alignment of nanofiber bundles induced by the electric field and longitudinal stretching exerted by electrical and mechanical forces.  The facile spinning conditions that are compatible with the use of aqueous media and room temperature make it possible to encapsulate live cells into these hydrogel fibers.  In collaboration with Prof. Sharon Gerecht, we cultured human endothelial progenitor cells (EPCs) on fibrin nanofiber scaffolds and showed that surface alignment facilitates EPC differentiation and generates a tubular cell sheet mimicking the endothelial capillary with extensive secretion of extracellular matrix molecules (Barreto-Ortiz, 2013; 2015). These hydrogel fibers with internal alignment feature can be used to prepare natural polymer scaffolds to provide guidance cues for generating tissues with alignment structure.

Publications

1. Zhang S, Liu X, Barreto-Ortiz SF, Yu Y, Ginn BP, DeSantis NA, Hutton DL, Grayson WL, Cui FZ, Korgel BA, Gerecht S, Mao HQ. (2014). Creating polymer hydrogel microfibres with internal alignment via electrical and mechanical stretching. Biomaterials. 35(10): 3243-3251. PMCID: PMC3923323.
2. Barreto-Ortiz SF, Zhang S, Davenport M, Fradkin J, Ginn B, Mao HQ, Gerecht S. (2013). A novel in vitro model for microvasculature reveals regulation of circumferential ECM organization by curvature. PLoS One. 8(11): e81061. PMCID: PMC3836741.
3. Barreto-Ortiz SF, Fradkin J, Eoh J, Trivero J, Davenport M, Ginn B, Mao HQ, Gerecht S. (2015). Fabrication of 3-dimensional multicellular microvascular structures. FASEB J. 29(8): 3302–3314. PMID: 25900808.
4. Li X, Tzeng SY, Liu X, Tammia M, Cheng YH, Rolfe A, Sun D, Zhang N, Green JJ, Wen X, Mao HQ. (2016). Nanoparticle-mediated transcriptional modification enhances neuronal differentiation of human neural stem cells following transplantation in rat brain. Biomaterials. 84: 157–166. PMID: 26828681