Complex Scaffold Design
Electrospinning is a simple method that is extensively to produce nano- and micro-fibers to fabricate scaffolds in tissue engineering and regenerative medicine. In this technique polymer solution is extruded under high electric field onto a conductive surface. The solvent evaporates as the fibers are deposited onto the substrate. The technique can be applied to a variety of polymers to produce sub-micron diameter fibers with and different spatial orientation resulting in fiber mats with very different architectures. Electrospun constructs seeded with cells have been used as scaffolds to engineer tissues such as skin, cornea, and neural tissue. Pore size and distribution are important criteria in developing strategies for the design and fabrication of these scaffolds. We recently described a procedure to fabricate a novel hybrid extracellular matrix (ECM)-synthetic scaffold biomaterial by cell-mediated deposition of ECM within an electrospun fiber mat.
Tissue engineering is an emerging field that aims to replace missing or damaged natural tissues and restore their functions. Three-dimensional (3D) printing is at the heart of the tissue engineering field which enables design and production of scaffolds with controlled shape, size and porosity specific for patients. LBR lab has a variety of different types of 3D printers which are actively used for many applications varying from tissue engineered scaffolds to surgical tools. Currently our main focus is to create a library of 3D printable novel polymers out of our huge tyrosol derived polymer library. These 3D printable polymers offers a great advantage over commercially available polymers in terms of processability and our lab has ability to create a wide range of novel polymers with varying features.
No single technique for fabricating scaffolds including electrospinning, porogen leaching and 3D printing can provide a combination of pore size distribution, favorable interaction with cells and the desired strength for any particular application. Therefore, hierarchical scaffolds constructed at different length scales are engineered to meet this diversity of challenges. One such attempt is a composite scaffold fabricated by combining 3D printed struts and airbrushed fibers. The resolution of 3D printed structures is such that the pores in 3D printed objects are too large to support cells. In contrast, dense packing of the fibers in electrospun and airbrushed fiber mats does not promote cell infiltration and nutrient transport in mats of a significant thickness. This results in limited three-dimensional volume and smaller pore sizes while also being weak mechanically and difficult to handle. To take advantage of the strengths of the two techniques while minimizing their weaknesses, we have developed hierarchical scaffolds combining airbrushed microfiber mats periodically interspersed within a FDM 3D printed support as a way to open up the fiber mat structure to allow for improved cell penetration while maintaining the rapid manufacturing and customization and improving the cell interactivity of 3D printed scaffolds.These hierarchical scaffolds show cell penetration, extensive fibronectin deposition from cells cultured on the scaffolds, durability during processing, and improved tissue integration in vivo.