Rapid 3-D laser microprinting of bioscaffolds and patterning of proteins

Abstract

Tissue engineers have been developing biological substitutes to regenerate or replace damaged tissue. Tissues contain both exquisite microarchitectures and chemical cues to support cell migration, proliferation and differentiation. The majority of tissue engineering strategies use porous scaffolds containing chemical cues for culturing cells. However, these methods are unable to truly recapitulate the complexity of the in-vivo environment, limiting the effective regeneration. Several techniques have been developed to create three-dimensional patterns of proteins and 3-D print the architectures of bio-scaffolds for studying and directing cell development. Scott has developed a rapid 3-D laser microprinting system', which is able to simultaneously print the defined architecture of scaffolds and internal patterns of proteins inside scaffolds with high-speed and high-resolution. The object of this thesis is to further develop the technique of rapid 3-D laser microprinting by researching on the biological activity and functions of printed scaffolds and printed proteins. First, we constructed branched collagen microchannels containing microprinted patterns of P-selectin, a protein involved in leukocyte recruitment from blood vessels. We showed that leukocyte rolling occurred on P-selectin patterned collagen channels. Second, we presented a 3-D printed microvasculature by seeding endothelial cells into a printed collagen scaffold with capillary-like microarchitecture. Next, we performed leukocyte rolling assay within the printed microvasculature by printing the patterns of protein cues to activate the endothelium. Last, we created a 3-D microprinted collagen scaffolds for guiding and homing of cells. Cells were guided by printed P-selectin patterns and trapped in specific locations inside collagen scaffolds. All the work demonstrated that printed protein cues retain their biological activity, and the combination of printed scaffolds and patterned protein cues provides potential application for drug screening assays in biomimetic environments and cell delivery for regenerative medicine. We believe that this rapid printing technology will enable highly engineered therapeutic scaffolds for regenerative medicine applications.