title: Design and characterization of a synthetically accessible, photodegradable hydrogel for user-directed formation of neural networks.
abstract: Hydrogels with photocleavable units incorporated into the cross-links have provided researchers with the ability to control mechanical properties temporally and study the role of matrix signaling on stem cell function and fate. With a growing interest in dynamically tunable cell culture systems, methods to synthesize photolabile hydrogels from simple precursors would facilitate broader accessibility. Here, a step-growth photodegradable poly(ethylene glycol) (PEG) hydrogel system cross-linked through a strain promoted alkyne-azide cycloaddition (SPAAC) reaction and degraded through the cleavage of a nitrobenzyl ether moiety integrated into the cross-links is developed from commercially available precursors in three straightforward synthetic steps with high yields (>95%). The network evolution and degradation properties are characterized in response to one- and two-photon irradiation. The PEG hydrogel is employed to encapsulate embryonic stem cell-derived motor neurons (ESMNs), and in situ degradation is exploited to gain three-dimensional control over the extension of motor axons using two-photon infrared light. Finally, ESMNs and their in vivo synaptic partners, myotubes, are coencapsulated, and the formation of user-directed neural networks is demonstrated.
authors.affiliation: Department of Chemical and Biological Engineering, ‡BioFrontiers Institute, and §Howard Hughes Medical Institute, University of Colorado , Boulder, Colorado 80303, United States.
authors.forename: Daniel D
authors.initials: DD
authors.lastname: McKinnon
authors.forename: Tobin E
authors.initials: TE
authors.lastname: Brown
authors.forename: Kyle A
authors.initials: KA
authors.lastname: Kyburz
authors.forename: Emi
authors.initials: E
authors.lastname: Kiyotake
authors.forename: Kristi S
authors.initials: KS
authors.lastname: Anseth
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D018929:Cell Culture Techniques; D002460:Cell Line; D057930:Click Chemistry; D003470:Culture Media / Q000737:chemistry; D053595:Embryonic Stem Cells / Q000502:physiology; D020100:Hydrogels / Q000737:chemistry; D051379:Mice; D032446:Myoblasts / Q000502:physiology; D009415:Nerve Net / Q000166:cytology*; D010782:Photolysis; D011092:Polyethylene Glycols / Q000737:chemistry*
chemical_list: D003470:Culture Media; D020100:Hydrogels; D011092:Polyethylene Glycols