Roofed grooves: Rapid layer engineering of perfusion channels in collagen tissue models

Abstract

Surface patterning (micro-moulding) of dense, biomimetic collagen is a simple tool to produce complex tissues using layer-by-layer assembly. The aim here was to channelise three-dimensional constructs for improved perfusion. Firstly, collagen fibril accumulation was measured by comparative image analysis to understand the mechanisms of structure formation in plastically compressed collagen during µ-moulding. This showed that shape (circular or rectangular) and dimensions of the template affected collagen distribution around moulded grooves and consequently their stability. In the second part, this was used for effective fabrication of multi-layered plastically compressed collagen constructs with internal channels by roofing the grooves with a second layer. Using rectangular templates of 25/50/100 µm widths and 75 µm depth, grooves were µ-moulded into the fluid-leaving surface of collagen layers with predictable width/depth fidelities. These grooves were then roofed by addition of a second plastically compressed collagen layer on top to produce µ-channels. Resulting µ-channels retained their dimensions and were stable over time in culture with fibroblasts and could be cell seeded with a lining layer by simple transfer of epithelial cells. The results of this study provide a valuable platform for rapid fabrication of complex collagen-based tissues in particular for provision of perfusing microchannels through the bulk material for improved core nutrient supply.

Fabrication of dense anisotropic collagen scaffolds using biaxial compression

“…However, while maintaining the same initial collagen concentration, gel volume, and magnitude of compression used for this study, we expect that the maximum achievable porogen concentration would not be great enough to compromise scaffold integrity. Additional surface morphologies, such as a crimp pattern similar to that observed at the fiber level of native tissues, can also be generated using multistage compression and a patterned compression surface [27, 33, 60]. Varying these parameters will facilitate the manufacture of tailored scaffolds for cell culture studies, and provide the ability to engineer tissue-specific scaffolds.…”

Robust Topographical Micro-Patterning of Nanofibrillar Collagen Gel by In Situ Photochemical Crosslinking-Assisted Collagen Embossing

“…[ 14 , 15 ]. These advantageous features of collagen gel have stimulated the development of various methods (e.g., chemical crosslinking [ 16 , 17 , 18 ], surface coating [ 19 ], air-drying [ 10 ], and collagen compression-based embossing [ 20 , 21 ]) to fabricate micro-patterned collagen constructs mimicking the complex features of native ECM. Among all of these methods, collagen compression-based embossing showed potential in the production of micro-patterned collagen constructs, due to its facile and rapid fabrication procedure compared to conventional approaches: it requires only one step of mechanical compression to achieve the compaction of collagen nanofibrils into a micro-patterned master mold with the dehydration [ 18 ].…”

“…Among all of these methods, collagen compression-based embossing showed potential in the production of micro-patterned collagen constructs, due to its facile and rapid fabrication procedure compared to conventional approaches: it requires only one step of mechanical compression to achieve the compaction of collagen nanofibrils into a micro-patterned master mold with the dehydration [ 18 ]. Moreover, the micro-patterns over the surface of the fabricated construct typically present a dense collagen nanofibrillar architecture similar to that of native tissues (e.g., skin dermis, muscle, and cornea) [ 3 , 20 , 22 , 23 ]. Nonetheless, the practical and wide-utilization of this approach in biological applications is limited, because fabricated micro-patterns can be readily disrupted by rehydration in aqueous solutions (e.g., cell culture medium or phosphate-buffered saline; PBS) and manual handling.…”

Fetal subcutaneous cells have potential for autologous tissue engineering

“…Conventional collagen‐based hydrogels have been used for tissue‐engineered constructs for various clinical conditions (Levis et al, ; Tan, Alekseeva, & Brown, ). The collagen gel supports cell proliferation and 3D environmental organization, but does not have the mechanical strength necessary for a graft (Ajalloueian, Zeiai, Rojas, Fossum, & Hilborn, ; Braziulis et al, ).…”