Injection of soluble cell signaling factors into degenerated intervertebral discs (IVDs) offers a minimally invasive treatment that could limit the processes of degeneration by stimulating native matrix repair. This study evaluated the regenerative capacity of degenerated nucleus pulposus (NP) cells obtained from patients undergoing anterior interbody fusions by measuring metabolic activity, DNA content, glycosaminoglycan (GAG) content, and cellular phenotype using qRT-PCR profiling with a custom array of 42 genes. NP cells were cultured in alginate for 7 days with 4 treatment groups: transforming growth factor beta 3 (TGFβ3) + dexamethasone (Dex), soluble factors released from notochordal cells (NCs) cultured in alginate (NCA), soluble factors released from NCs in their native tissue environment (NCT), and basal media. TGFβ3 + Dex stimulated degenerated human NP cells to proliferate and exhibit an anti-catabolic gene expression profile (with a decrease in ADAMTS5 and MMP1 compared to basal, and an increase in SOX9, decrease in ADAMTS5, MMP1, collagen I and collagen III compared to day 0), while NCA stimulated the greatest GAG per cell. We conclude that degenerated human NP cells exhibit regenerative potential, and that an optimal treatment will likely require treatments, such as TGFβ3 + Dex, which were able to increase cell metabolism and reduce catabolism, as well as treatments with factors found in NC conditioned medium, that were able to produce high amounts of GAG per cell. Additional studies to optimize NC culture conditions are required to determine if NC conditioned medium can be made with the capacity to enhance NP cell proliferation and metabolism.

A larger population is necessary to characterize the range of anatomic variations in arterial supply within the foramina. Available studies support the current technique of fluoroscopic needle insertion. Yet, there is wide anatomic variation in the origin and location of these vessels, and even with strict adherence to technique, it is feasible that a properly placed needle could penetrate a radicular artery.

Study Design-In vitro and in vivo rat tail model to assess effects of torsion on intervertebral disc biomechanics and gene expression.Objective-Investigate effects of torsion on promoting biosynthesis and producing injury in rat caudal intervertebral discs.Summary of Background Data-Torsion is an important loading mode in the disc and increased torsional range of motion is associated with clinical symptoms from disc disruption. Altered elastin content is implicated in disc degeneration, but its effects on torsional loading are unknown. Although effects of compression have been studied, the effect of torsion on intervertebral disc gene expression is unknown.Methods-In vitro biomechanical tests were performed in torsion on rat tail motion segments subjected to 4 treatments: elastase, collagenase, genipin, control. In vivo tests were performed on rats with Ilizarov-type fixators implanted to caudal motion segments with five 90-minute loading groups: 1 Hz cyclic torsion to ±5°, ±15°, and ±30°, static torsion to +30°, and sham. Anulus and nucleus tissues were separately analyzed using qRT-PCR for gene expression of anabolic, catabolic, and proinflammatory cytokine markers.Results-In vitro tests showed decreased torsional stiffness following elastase treatment and no changes in stiffness with frequency. In vivo tests showed no significant changes in dynamic stiffness with time. Cyclic torsion upregulated elastin expression in the anulus fibrosus. Upregulation of TNF-α and IL-1β was measured at ±30°.Conclusion-We conclude that strong differences in the disc response to cyclic torsion and compression are apparent with torsion increasing elastin expression and compression resulting in a more substantial increase in disc metabolism in the nucleus pulposus. Results highlight the importance of elastin in torsional loading and suggest that elastin remodels in response to shearing. Torsional loading can cause injury to the disc at excessive amplitudes that are detectable biologically before they are biomechanically. ©2010, Lippincott Williams & WilkinsAddress correspondence and reprint requests to James C. Iatridis, PhD, University of Vermont, 33 Colchester Ave, 201 Perkins Hall, Burlington, VT 05405; James.iatridis@uvm.edu. NIH Public AccessAuthor Manuscript Spine (Phila Pa 1976 The causes of intervertebral disc (IVD) degeneration are multifaceted, with contributions from aging, mechanical, genetic, and nutritional factors. 1 IVD degeneration is manifested biochemically through a loss of glycosaminoglycans, regional changes in collagen matrix composition 2 as well as changes in elastin structure 3,4 and content. 5 An increase in expression of proteases and their inhibitors, 6,7 including MMP-3, ADAMTS-4, and TIMP-1 as well as cytokines IL-1β 8 and TNF-α 9 have also been associated with degeneration. Biomechanically, IVD degeneration is characterized by a decrease in intradiscal and osmotic pressure, 10,11 an altered range of motion and reduced neutral zone, 12-14 and a decrease in creep and creep rate. 15,16 Although...

Kinetics of mRNA expression following a single loading event was measured using an in vivo rat tail model. Animals were instrumented and loaded in compression for 1.5 h at 1 MPa and 1 Hz. Real-time RT-PCR was used to measure mRNA levels 0, 8, 24 and 72 h after mechanical stimulation for genes associated with matrix proteins (aggrecan, collagen-I, collagen-II), proteases (MMP-2, MMP-3, MMP-13, ADAMTS-4), and their inhibitors (TIMP-1, TIMP-3) in anulus fibrosus and nucleus pulposus regions. Baseline mRNA levels were of greatest abundance for matrix proteins and lowest for proteases. The mRNA levels reached maximum levels 24 h following mechanical stimulation for the majority of genes evaluated, but some had maximum levels 8 and 72 h following loading. The mRNA levels returned to baseline levels for all genes in the nucleus 72 h following loading, but the majority of genes in the anulus remained upregulated. Results support a coordinated strategy of relative mRNA expression that varied over time beginning with inhibition of tissue breakdown, followed by synthesis of aggrecan and matrix degrading enzymes, and eventually collagen metabolism days following loading. Consequently, optimal time for tissue harvest for mRNA measurements depends on genes of interest. Results suggest attempts at anabolic remodeling must be given adequate time for metabolic processes and protein synthesis to occur, and that changes in TIMP and MMP levels may have greater potency in affecting structural protein abundance than direct changes in the structural protein messages. Results have important implications for disc remodeling and tissue engineering. ß

No abstract