Injectable, high-density collagen gels for annulus fibrosus repair: An in vitro rat tail model.

Publication Type	Academic Article
Authors	Borde B, Grunert P, Härtl R, Bonassar L
Journal	J Biomed Mater Res A
Volume	103
Issue	8
Pagination	2571-81
Date Published	12/29/2014
ISSN	1552-4965
Keywords	Collagen, Intervertebral Disc Displacement, Models, Biological
Abstract	A herniated intervertebral disc often causes back pain when disc tissue is displaced through a damaged annulus fibrosus. Currently, the only methods available for annulus fibrosus repair involve mechanical closure of defect, which does little to address biological healing in the damaged tissue. Collagen hydrogels are injectable and have been used to repair annulus defects in vivo. In this study, high-density collagen hydrogels at 5, 10, and 15 mg/mL were used to repair defects made to intact rat caudal intervertebral discs in vitro. A group of gels at 15 mg/mL were also cross-linked with riboflavin at 0.03 mM, 0.07 mM, or 0.10 mM. These cross-linked, high-density collagen gels maintained their presence in the defect under loading and contributed positively to the mechanical response of damaged discs. Discs exhibited increases to 95% of undamaged effective equilibrium and instantaneous moduli as well as up to fourfold decreases in effective hydraulic permeability from the damaged discs. These data suggest that high-density collagen gels may be effective at restoring mechanical function of injured discs as well as potential vehicles for the delivery of biological agents such as cells or growth factors that may aid in the repair of the annulus fibrosus.
DOI	10.1002/jbm.a.35388
PubMed ID	25504661
PubMed Central ID	PMC4465422