(i) Current understanding of low back pain and intervertebral disc degeneration: epidemiological perspectives and phenotypes for genetic studies

MicroRNA-223 inhibits lipopolysaccharide-induced inflammatory response by directly targeting Irak1 in the nucleus pulposus cells of intervertebral disc

This study was aimed to research the effect of miR-223 on the inflammatory responses induced by lipopolysaccharide (LPS) in nucleus pulposus (NP) cells of rat intervertebral disc. Isolated rat NP cells were induced by LPS. Reverse transcriptase quantitative real-time polymerase chain reaction was used to detect gene expression. To detect protein expression, Western blot and enzyme-linked immunosorbent assay experiments were applied. The putative targeting relationship between miR-223 and Irak1 was determined using dual-luciferase reporter gene assay. We found that miR-223 was downregulated in LPS-induced NP cells. MiR-223 upregulated the expression of extracellular matrix-related genes (Aggrecan and Collagen II). Matrix degrading enzymes (ADAMTS4, ADAMTS5, MMP3 and MMP13), NO reaction-associated proteins (PGE2, COX-2 and INOS) and the expression of nuclear factor (NF)-κB signaling-related proteins were downregulated after miR-233 overexpression. In addition, luciferase reporter assays demonstrated that miR-223 directly targeted Irak1. MiR-223 overexpression could inhibit NF-κB signaling by targeting Irak1, and finally suppress the LPS-induced inflammation in NP cells. © 2018 IUBMB Life, 70(6):479-490, 2018.

Nanocellulose reinforced gellan-gum hydrogels as potential biological substitutes for annulus fibrosus tissue regeneration

Intervertebral disc (IVD) degeneration is associated with both structural damage and aging related degeneration. Annulus fibrosus (AF) defects such as annular tears, herniation and discectomy require novel tissue engineering strategies to functionally repair AF tissue. An ideal construct will repair the AF by providing physical and biological support, facilitating regeneration. The presented strategy herein proposes a gellan gum-based construct reinforced with cellulose nanocrystals (nCell) as a biological self-gelling AF substitute. Nanocomposite hydrogels were fabricated and characterized with respect to hydrogel swelling capacity, degradation rate in vitro and mechanical properties. Rheological evaluation on the nanocomposites demonstrated the GGMA reinforcement with nCell promoted matrix entanglement with higher scaffold stiffness observed upon ionic crosslinking. Compressive mechanical tests demonstrated compressive modulus values close to those of the human AF tissue. Furthermore, cell culture studies with encapsulated bovine AF cells indicated that nanocomposite constructs promoted cell viability and a physiologically relevant cell morphology for up to fourteen days in vitro.