Small intestinal submucosa as a potential bioscaffold for intervertebral disc regeneration

Study Design. To evaluate the capacity of porcine small intestine submucosa to support the in vitro proliferation of human disc cells and the synthesis of extracellular matrix that could restore the biochemical properties of the disc. Objective. To evaluate if porcine small intestine submucosa is a potential bioactive scaffold for rescuing degenerative disc cells. Summary of Background Data. Discogenic back pain is associated with alterations of the disc and abnormal turnover of the disc extracellular matrix. We hypothesize that a biodegradable and biocompatible acellular scaffold such as small intestine submucosa, which contains entrapped growth factors, may stimulate disc cells to synthesize extracellular matrix, thereby arresting the degeneration, or even promoting the regeneration, of the disc. Methods. Human degenerative anulus and nucleus cells were seeded onto small intestine submucosa scaffolds, and evaluated over a 3-month period for cell growth (proliferation assay, deoxyribonucleic acid content) and matrix composition (glycosaminoglycan and collagen contents). Results. As hematoxylin and eosin staining revealed, more than 70% of seeded cells attached to the small intestine submucosa surface and invaded throughout the scaffold. The macroscopic appearance of cell-seeded scaffolds was dramatically modified over time. Cell metabolic activity was confirmed for up to 3 months. Seeded scaffolds showed a higher glycosaminoglycan content as compared to control scaffolds. Toluidine blue staining detected large areas of proteoglycans. Positive gene expression for collagens I, II, and X, aggrecan, and Sox-9 confirmed deposition of new extracellular matrix components. Conclusions. This pilot study shows that small intestine submucosa is a promising bioactive material that could potentially serve as a temporary scaffold for intervertebral disc regeneration.