Table 1.
Anulus fibrosus repair
| Method | Description | Results | Reference(s) |
|---|---|---|---|
| Suture repair methods | |||
| XClose™ tissue repair | Polymeric suture with soft tissue anchors | Reduced recurrent disc herniation rate up to 2 years; no adverse events | 124 |
| Barricaid™ | Polymer mesh with titanium anchor to vertebral body rim | At 2-year follow-up, tear closure was associated with no recurrent disc herniation and maintenance of disc height | 125 |
| Patch- or void-filling methods | |||
| PTMC scaffold covered with a sutured PU membrane | Human MSCs | Restored disc height in IVD degeneration model and prevented recurrent NP herniation; MSCs seeded onto PTMC had elevated markers of AF phenotype | 126 |
| Porous silk fibroin | Bovine AF cells | Cells attached and produced matrix; conjugation with RGD peptide had no effect on cell attachment or morphology | 111 |
| Electrospun PCL | Bovine AF cells | Reproduced the anisotropic, angle-ply laminate structure of AF; cells aligned along predominant fiber direction; integration was shown with engineered NP in vivo | 80, 81, 115 |
| BMG with PPCLM | Murine AF cells | Supported AF cell survival, alignment, and matrix accumulation; stiffness and degradation was adjusted by postpolymerization time; gelatin component assisted integration and tensile strength | 127 |
| POM | Murine AF cells | Supported cell infiltration, elongation, and matrix accumulation; tensile strength and degradation time increased with polymerization time | 128 |
| PDLLA/Bioglass | Human AF cells | Foam supported cell cultures and supported cell proliferation and sGAG, collagen type I and collagen type II production | 129 |
| Electrospun PU and PCL | Bovine AF cells | Electrospinning increased “yield strain,” promoted AF cell phenotype with retention of collagen and glycosaminoglycan compared with films | 130 |
| Fibrin cross-linked with genipin | Human AF cells | Demonstrated suitable mechanical properties that restored compressive properties to IVD; promoted adhesion and elongation; maintained viability of cell population; had a slower in vitro degradation rate | 131 |
| Photochemically crosslinked collagen in shape of needle | Placed following intradiscal delivery of MSCs in microsphere carriers | Restored compressive properties to IVD, reduced cell leakage, withstood torsional push-out test. In rabbit model, needle shape revealed placement of the device | 69 |
| Collagen cross-linked with riboflavin | No cells | Retained in defect under loading and contributed to restored compressive moduli of IVD | 132 |
Abbreviations: AF, annulus fibrosus; BMG composite bone gelatin; IVD, intervertebral disc; MSC, mesenchymal stem cell; NA, not applicable; NP, nucleus pulposus PCL, poly(ε-caprolactone); PDLLA: poly-D,L-lactic acid; POM, poly(1,8-octanediol malate); PPCLM, poly(poly-caprolactone triol malate); PTMC; poly(trimethylene carbonate); PU; poly(ester-urethane); RGD, arginylglycylaspartic acid; sGAG: sulfated glycosaminoglycans.