April 19, 2006 A team of researchers at Singapore’s Institute of Bioengineering and Nanotechnology (IBN) have successfully created artificial fibres with nanometer-sized features that can be used to grow cells and tissue structures. These ‘fibrous scaffolds’ have been imbued with features of the natural extracellular matrix, the ground substance in which cells are embedded and a vital component in the engineering of human tissues.
Scaffolds are ‘templates’ upon which the desired cell type or precursor is seeded for the growth of different tissues. Signaling molecules can also be incorporated into these structures to instruct or regulate cell growth and differentiation. Using IBN’s fibrous scaffolds, tissue engineers, for example, would be able to take a patient’s own cells, grow it into tissue in the lab, and subsequently implant the developed tissue back into the patient.
While much work has been done to engineer suitable scaffolds, conventional production methods involve the use of high temperatures, organic solvents and/or a leaching step to develop porosity. Such conditions compromise the biological activity of proteins, and thus pose problems in the incorporation of biological molecules within the scaffolds.
IBN, however, has been able to create fibers by interfacial polyelectrolyte complexation, which is a mild, aqueous-based process that takes place at ambient temperature. A method called ‘hydroentanglement’ that employs water pressure is then used to entangle the fibers into scaffolds. Previous work in this area was hampered by the tendency of the fibers to clump and form a dense monolith of low porosity.
IBN scientists solved this problem by incorporating silica, an inorganic material that is found in simple marine organisms and some forms of glass, effectively crosslinking the fibers to obtain porous 3-D scaffolds. The porosity or permeability of the scaffold is important because a scaffold with a high surface-to-volume ratio provides for better interaction of cells with the matrix, and thus a better environment for the culture of various cell types for tissue engineering.
Results have shown that cells could adhere and grow well on IBN’s fibrous scaffolds after they were incorporated with components such as collagen, fibronectin and cell-adhesion peptides. “We have created scaffolds based on natural polymers and extracellular matrix components that can be specially tailored for the adhesion and proliferation of a variety of cells,” said IBN Principal Research Scientist Dr Andrew Wan, who is the team leader of the project. “Hence, these scaffolds would have many potential applications in the engineering of tissues as implants, or as in vitro models for drug development.” This research was recently published in the March issue of the journal, Advanced Materials. The work on the “Three-Dimensional Reconstituted Extracellular Matrix Scaffolds for Tissue Engineering” also won an Outstanding Paper Award at the 12th International Conference on Biomedical Engineering in December 2005.
A US patent has been filed on the invention.