Making Tissue Engineering Scaffolds Work. Review: The application of solid freeform fabrication technology to the production of tissue engineering scaffolds

Abstract

Tissue engineering is a new and exciting technique which has the potential to create tissues and organs de novo. It involves the in vitro seeding and attachment of human cells onto a scaffold. These cells then proliferate, migrate and differentiate into the specific tissue while secreting the extracellular matrix components required to create the tissue. It is evident, therefore, that the choice of scaffold is crucial to enable the cells to behave in the required manner to produce tissues and organs of the desired shape and size. Current scaffolds, made by conventional scaffold fabrication techniques, are generally foams of synthetic polymers. The cells do not necessarily recognise such surfaces, and most importantly cells cannot migrate more than 500µm from the surface. The lack of oxygen and nutrient supply governs this depth. Solid freeform fabrication (SFF) uses layer-manufacturing strategies to create physical objects directly from computer-generated models. It can improve current scaffold design by controlling scaffold parameters such as pore size, porosity and pore distribution, as well as incorporating an artificial vascular system, thereby increasing the mass transport of oxygen and nutrients into the interior of the scaffold and supporting cellular growth in that region. Several SFF systems have produced tissue-engineering scaffolds with this concept in mind, which will be the main focus of this review. We are developing scaffolds from collagen and with an internal vascular architecture using SFF. Collagen has major advantages as it provides a favourable surface for cellular attachment. The vascular system allows for the supply of nutrients and oxygen throughout the scaffold. The future of tissue engineering scaffolds is intertwined with SFF technologies.

Cell colonization in degradable 3D porous matrices

“…The fibers may be distributed randomly, as in electrospinning [103][104][105] or form a highly organized system with regular repeating pore units, as in solid freeform fabrication. 106 Thus the fiber thickness, length, width and shape (circular rectangular, etc.) must be evaluated.…”

Ink Jet printing of mammalian primary cells for tissue engineering applications

“…These techniques can fabricate scaffolds with the precision required to incorporate a complex interconnected internal architecture and the ability to tailor the structure to both the application and the individual [1][2][3]. The incorporation of cells into these scaffolds however still poses a significant problem.…”

Preclinical models for in vitro mechanical loading of bone-derived cells

“…The scaffold itself should encourage cell attachment and proliferation, be of a suitable stiffness for the required tissue and have porosity and pore interconnectivity, which allow the flow of nutrients and waste through the scaffold. [44][45][46][47] The stiffness, porosity and interconnectivity also affect the transmission of mechanical stimulation to the cells. For an open porous structure, fluid flow can pass through the scaffold and cause shear stress on the cells.…”