Osteoarthritis (OA) is a leading cause of joint pain, deformity and functional limitation. An imbalance of anabolic and catabolic activity results in destruction of the extracellular matrix of articular cartilage. While there is evidence to support the role of DNA methylation in the pathogenesis of OA, the effect of other epigenetic modifications is yet to be described. This study looks at the effect of two novel epigenetic modifiers, PFI-1, a bromodomain inhibitor, and SGC707, a histone methytransferase inhibitor, on gene expression in the pathogenesis of OA. Chondrocytes were extracted from OA femoral heads (n=6), cultured and incubated with increasing concentrations of the compounds. Cells were treated with media alone (control), interleukin 1-beta (IL-1β) plus oncostatin M (OSM) alone, or in combination with PFI-1 or SGC707. Levels of expression of iNOS, COX2, IL8, IL1B, matrix metalloproteinase-13 (MMP13), RUNX2 and COL9A1 were measured using qRT-PCR. PFI-1 (0.5 and 5µM) suppressed expression of catabolic genes in OA chondrocytes, at basal levels and when co-stimulated with IL-1β+OSM. While there was a decrease in catabolic gene expression (iNOS, COX2, IL8, IL1B and MMP13), RUNX2 expression was also supressed. There was no effect on expression of COL9A1, an anabolic chondrocytic gene. SGC707 (0.1 and 1µM) did not induce a reduction in expression of all the catabolic genes, with a less predictable effect on gene expression than PFI-1. This study has demonstrated that the BET inhibitor PFI-1 has a potent protective effect against cartilage degradation, through its action as an epigenetic modifier in modulating the expression of catabolic genes in OA chondrocytes. This further validates the role of epigenetics in OA, with potential implications for therapeutic interventions.
When transferring tissue regenerative strategies
involving skeletal stem cells to human application, consideration needs
to be given to factors that may affect the function of the cells
that are transferred. Local anaesthetics are frequently used during
surgical procedures, either administered directly into the operative
site or infiltrated subcutaneously around the wound. The aim of
this study was to investigate the effects of commonly used local anaesthetics
on the morphology, function and survival of human adult skeletal
stem cells. Cells from three patients who were undergoing elective hip replacement
were harvested and incubated for two hours with 1% lidocaine, 0.5%
levobupivacaine or 0.5% bupivacaine hydrochloride solutions. Viability
was quantified using WST-1 and DNA assays. Viability and morphology
were further characterised using CellTracker Green/Ethidium Homodimer-1
immunocytochemistry and function was assessed by an alkaline phosphatase
assay. An additional group was cultured for a further seven days
to allow potential recovery of the cells after removal of the local
anaesthetic. A statistically significant and dose dependent reduction in cell
viability and number was observed in the cell cultures exposed to
all three local anaesthetics at concentrations of 25% and 50%, and
this was maintained even following culture for a further seven days. This study indicates that certain local anaesthetic agents in
widespread clinical use are deleterious to skeletal progenitor cells
when studied
The complications of impaction bone grafting in revision hip replacement includes fracture of the femur and subsidence of the prosthesis. In this We found that the peak loads and hoop strains transmitted to the femoral cortex during graft compaction and subsidence of the stem in subsequent mechanical testing were reduced. This innovative technique has the potential to reduce the risk of intra-operative fracture and to improve graft compaction and therefore prosthetic stability.
