Wet extrusion of fibronectin-fibrinogen cables for application in tissue engineering

• Published in: Biotechnology and bioengineering Vol. 73; no. 4; pp. 295 - 305
• Main Authors: Underwood, S., Afoke, A., Brown, R. A., MacLeod, A. J., Shamlou, P. Ayazi, Dunnill, P.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 20.05.2001; Wiley
• Subjects: Alginates - chemistry; Biological and medical sciences; Biomedical Engineering; Biotechnology; Carboxymethylcellulose Sodium - chemistry; Coagulants - chemistry; Culture Techniques; Extracellular Matrix - chemistry; fibrinogen; Fibrinogen - chemistry; Fibrinogen - ultrastructure; fibronectin; Fibronectins - chemistry; Fibronectins - ultrastructure; Fundamental and applied biological sciences. Psychology; Glucuronic Acid; Health. Pharmaceutical industry; Hexuronic Acids; Humans; Industrial applications and implications. Economical aspects; Microscopy, Electron, Scanning; Miscellaneous; protein fibers; Rheology; tissue engineering; wet spinning; Tissue engineering; Medical application; Fibronectin; Wet spinning; Composite material; Fibrinogen
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.1062

A method for the wet extrusion of human plasma‐derived fibronectin–fibrinogen cables is described. Solutions of fibronectin and fibrinogen with and without sodium alginate and carboxymethylcellulose (CMC) are tested. The rheological properties of the protein solutions changed from Newtonian to shear thinning non‐Newtonian in the presence of small quantities of these additives, the apparent viscosity increased, and the extrusion properties of the protein solutions improved. Cables were prepared using a capillary with a diameter of 1 mm and overall length of 18 mm. Cable diameter was reduced to about 0.5 mm by drawing using a series of rollers. Cables prepared with sodium alginate were found to have suitable properties, and those made with CMC were sticky and difficult to handle. Solutions containing no sodium alginate required a minimum total protein concentration of about 70 mg/mL for extrusion. Extruded cables were prepared with solutions containing 140 mg/mL total protein with 12.9 mg/mL alginate (high protein), and 46 mg/mL total protein with 47.6 mg/mL of sodium alginate (high alginate). The mechanical strength of the extruded cables was within the range suitable for application in tissue engineering. Extrusion of the protein solutions into cables was achieved in a coagulation bath. Cables with a mechanical strength of approximately 30 N/mm2, suitable for wound repair and nerve regeneration applications, were prepared with a coagulation bath containing 0.25 M HCl, 2% CaCl2 at a pH of <0.9. These cables also had a large average elongation at break of 52%, and showed an increase in cable length after breakage (permanent set) of 20%, demonstrating the potential for drawing the cables down to a fine diameter. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 295–305, 2001.