Insulin released from titanium discs with insulin coatings-Kinetics and biological activity.

Local administration of insulin from a titanium surface has been demonstrated to increase bone formation in non-diabetic rats. The authors hypothesized that insulin was released from the titanium surface and with preserved biological activity after the release. Thus, in the present in vitro study, human recombinant insulin was immobilized onto titanium discs, and the insulin release kinetics was evaluated using Electro-chemiluminescence immunoassay. Neutral Red uptake assay and mineralization assay were used to evaluate the biological effects of the released insulin on human osteoblast-like MG-63 cells. The results confirmed that insulin was released from titanium surfaces during a six-week period. Etching the disc prior to insulin coating, thickening of the insulin coating and incubation of the discs in serum-enriched cell culture medium increased the release. However, longer storage time decreased the release of insulin. Furthermore, the released insulin had retained its biological activity, as demonstrated by the significant increase in cell number and a stimulated mineralization process, upon exposure to released insulin. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1847-1854, 2017.

A potential role of chondroitin sulfate on bone in osteoarthritis: inhibition of prostaglandin E2 and matrix metalloproteinases synthesis in interleukin-1ß-stimulated osteoblasts.

OBJECTIVES: To determine the effect of chondroitin sulfate (CS) on inflammatory mediators and proteolytic enzymes induced by interleukin-1ß (IL-1ß) and related to cartilage catabolism in murine osteoblasts. DESIGN: Osteoblasts were obtained by enzymatic digestion of calvaria from Swiss mice and cultured for 3 weeks as a primary culture. Cells were then stimulated with IL-1ß (1 or 10 ng/ml). CS-treated osteoblasts were incubated with 100 µg/ml of CS during the last week of culture w/o IL-1ß for the last 24 h. Expressions of cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-1 (mPGES-1), 15-PG dehydrogenase (15-PGDH), matrix metalloproteinases-3 and -13 (MMP-3 and -13), osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) were determined by real-time polymerase chain reaction (PCR). PGE2, MMP-3 and MMP-13 release were assessed in the medium by enzyme-linked immunosorbent assay or western-blotting. RESULTS: IL-1ß increased COX-2, mPGES-1, MMP-3, MMP-13, RANKL expressions, decreased 15-PGDH expression, and increased PGE2, MMP-3 and MMP-13 release. Interestingly, 7 days of CS treatment significantly counteracted IL-1ß-induced expression of COX-2 (-62%, P<0.001), mPGES-1 (-63%, P<0.001), MMP-3 (-39%, P=0.08), MMP-13 (-60%, P<0.001) and RANKL (-84%, P<0.001). Accordingly, IL-1ß-induced PGE2, MMP-3 and MMP-13 releases were inhibited by 86% (P<0.001), 58%(P<0.001) and 38% (P<0.01) respectively. CONCLUSIONS: In conclusion, our data demonstrate that, in an inflammatory context, CS inhibits the production of PGE2 and MMPs. Since CS has previously been shown to counteract the production of these mediators in chondrocytes, we speculate that the beneficial effect of CS in Osteoarthritis (OA) could not only be due to its action on cartilage but also on subchondral bone.