Riboflavin crosslinked high-density collagen gel for the repair of annular defects in intervertebral discs: An in vivo study.

Publication Type	Academic Article
Authors	Grunert P, Borde B, Towne S, Moriguchi Y, Hudson K, Bonassar L, Härtl R
Journal	Acta Biomater
Volume	26
Pagination	215-24
Date Published	06/23/2015
ISSN	1878-7568
Keywords	Collagen, Guided Tissue Regeneration, Intervertebral Disc Displacement, Riboflavin, Tissue Scaffolds, Total Disc Replacement
Abstract	Open annular defects compromise the ability of the annulus fibrosus to contain nuclear tissue in the disc space, and therefore lead to disc herniation with subsequent degenerative changes to the entire intervertebral disc. This study reports the use of riboflavin crosslinked high-density collagen gel for the repair of annular defects in a needle-punctured rat-tail model. High-density collagen has increased stiffness and greater hydraulic permeability than conventional low-density gels; riboflavin crosslinking further increases these properties. This study found that treating annular defects with crosslinked high-density collagen inhibited the progression of disc degeneration over 18 weeks compared to untreated control discs. Histological sections of FITC-labeled collagen gel revealed an early tight attachment to host annular tissue. The gel was subsequently infiltrated by host fibroblasts which remodeled it into a fibrous cap that bridged the outer disrupted annular fibers and partially repaired the defect. This repair tissue enhanced retention of nucleus pulposus tissue, maintained physiological disc hydration, and preserved hydraulic permeability, according to MRI, histological, and mechanical assessments. Degenerative changes were partially reversed in treated discs, as indicated by an increase in nucleus pulposus size and hydration between weeks 5 and 18. The collagen gel appeared to work as an instant sealant and by enhancing the intrinsic healing capabilities of the host tissue.
DOI	10.1016/j.actbio.2015.06.006
PubMed ID	26116448