Rapid Generation of 3D Microchannels Using a Multiphoton Laser System in Blended Hydrogels to Serve as Templates for Microvascular Generation
Burtch, Stephanie Renée
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Lack of scaffold microvascularization is one of the biggest problems facing graft survival and success within current tissue engineering applications. Fortunately, techniques aiming to form microchannels within three-dimensional scaffolds have shown promise in providing templates for tube-like cell formations. Unfortunately, many current patterning approaches are limited in the types of materials the technique can be applied to and lack the ability to form capillary-sized (<10 microns in diameter) networks. In this study, a multiphoton laser was used to create channels down to the micron level within an optically-clear hydrogel scaffold. Different percentages of poly (ethylene glycol) diacryate (PEGDA) and collagen were used to create different blends of hydrogels at 0%, 1%, 2%, and 3% collagen/PEGDA (w/w). Mechanical and transmittance testing were performed on all blends in order to determine which had optimal mechanical strength and optical clarity for laser subtractive printing. Swelling and degradation were measured to confirm the scaffolds served the tissue engineering requirement of eventual degradation. All gels with PEGDA incorporation showed an increase in mechanical stability and transparency when compared to pure collagen gels. Hydrogel blends showed resistance to degradation in phosphate-buffered saline, but appeared to exhibit collagen degradation in collagenase, although no statistical significance was seen. Cell viability tests within the hydrogels showed viability in cell-seeded hydrogels when compared to dead controls, although cells lacked some markers of healthy cells, such as spreading. In conclusion, results show that hydrogel blends provide a good matrix for subtractive optical micropatterning approaches, although other types of hydrogels may improve cell spreading and other cell responses.