The Effect of Adenosine on Extracellular Matrix Production in Porcine Intervertebral Disc Cells

Abstract

Compressive loading promotes adenosine triphosphate (ATP) production and release by intervertebral disc (IVD) cells. Extracellular ATP can be rapidly hydrolyzed by ectonucleotidases. Adenosine, one of the adenine derivatives of ATP hydrolysis, can modulate diverse cellular actions via adenosine receptors. The objectives of this study were to investigate the effects of exogenous adenosine on the production of extracellular matrix (ECM; i.e., collagen type II and aggrecan) and ATP of IVD cells and explore the underlying mechanism of action. It was found that adenosine treatment significantly upregulated aggrecan and type II collagen gene expression and the ATP level in IVD cells. Dipyridamole, an adenosine transport blocker, completely suppressed the effects of adenosine on the ATP production and ECM gene expression of the IVD cells, whereas antagonists of adenosine receptors did not significantly affect adenosine-treated IVD cells. The findings suggested that elevated intracellular ATP and upregulation of ECM gene expression by adenosine treatment are mainly due to adenosine uptake rather than receptor activation. Since ECM biosynthesis is a high ATP demanding process, supplementing adenosine could be beneficial as IVD cells are able to utilize it to replenish intracellular ATP and sequentially promote ECM production, which is constantly suppressed by limited nutrition supply due to the avascular nature of the IVD.

Effects of Glucose Deprivation on ATP and Proteoglycan Production of Intervertebral Disc Cells under Hypoxia

“…IVD cells were isolated by centrifugation and re-suspended in DMEM supplemented with 10% fetal bovine serum (FBS; Invitrogen Corp., Carlsbad, CA) and 1% antibiotic-antimycotic (Invitrogen Corp, Carlsbad, CA). All freshly isolated notochordal NP cells were seeded into three-dimensional (3D) agarose gel (Low gelling temperature, Sigma Chemical, St. Louis, MO) with an established protocol [78][79][80][81] to prevent phenotypic changes as suggested in literature 22,82,83 . Based on our previous study 84 , AF cells isolated from the same region expressed aggrecan and type II collgen, indicating a chondrocyte-like phenotype.…”

Mitochondrial Dysfunction in Intervertebral Disc Degeneration: From Pathogenesis to Therapeutic Target

“…The degeneration, driven by increased proteolysis of matrix components including aggrecan and type II collagen mediated by catabolic enzymes, like matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), is closely correlated to mitochondrial dysfunction in IVD cells [84]. On the one hand, anabolism of ECM requires ATP for providing energy [85] while mitochondrial dysfunction, showing ATP depletion, indeed reduces the anabolic process in IVD cells [69,86]. On the other hand, the mitochondrial-mediated ROS generation could significantly interrupt the metabolism of ECM.…”