doi:10.1038/nindia.2012.139 Published online 25 September 2012
New research has shown that silk-based scaffolds could replace a worn-out part of the intervertebral disc (IVD) in the human body. The researchers synthesized scaffolds using silk fibroin protein isolated from cocoons of the silk worm Antherea mylitta.
Such silk-based scaffolds couldhelp regenerate the annulus fibrosus (AF) tissue in IVD, alleviating low back pain and other diseases of spine.
The AF consists of 15-25 concentric layers of specially aligned collagen fibres. Age-related metabolic changes, mechanical stress and genetic disorders cause defects in AF tissue, leading to IVD degeneration. Physical exercise, painkillers, and implantation of ceramic discs are currently used to treat such disorders, but cannot fully restore the flexibility and load-bearing capacity of the original IVD.
The researchers designed the silk fibroin protein-based scaffolds as a potential alternative. They first cross-linked silk fibroin fibres with chondroitin sulphate (CS) isolated from bovine trachea. To mimic the structure of AF tissue, they used a winding machine to wrap cross-linked silk and CS around a silk fibroin protein-based hydrogel. This yielded silk-CS-conjugated scaffolds.
To probe the tissue-engineering efficacy of silk-CS scaffolds, the researchers grew human nasal chondrocytes on these scaffolds and tested their ability to support cell growth.
After two weeks, cells on the scaffolds formed clusters and produced extracellular matrix (ECM) proteins. After four weeks, the cells showed signs of redifferentiation with fibrous ECM proteins and collagen fibres resembling the structure of AF tissue.
"This new silk-based scaffold with a multi-layered architecture could be used to grow cells for simulating the precise architecture, typical micro-environment and biomechanical qualities of AF tissue," says lead researcher Sourabh Ghosh.
The authors of this work are from: Department of Textile Technology and Centre of Biomedical Engineering, Indian Institute of Technology, All India Institute of Medical Sciences and Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India, Departments of Surgery and Biomedicine, University Hospital of Basel, and Biozentrum and Swiss Nanoscience Institute, University of Basel, Switzerland, and School of Cellular & Molecular Medicine, University of Bristol, Bristol, UK.