Evaluation of the Proliferative Effects Induced by Low-Level Laser Therapy in Bone Marrow Stem Cell Culture.

OBJECTIVE: The objective of this study was to evaluate the effect of laser irradiation on dog bone marrow stem cells. BACKGROUND DATA: Low doses of low-level red laser positively affect the viability of mesenchymal stem cells, and also increase proliferation. METHODS: Low-level laser (wavelength, 660 nm; power output, 50 mW), was applied to dog bone marrow stem cell cultures (DBMSC). The energy densities delivered varied from 1 to 12J/cm(2). The effect of the laser irradiation was evaluated on cell proliferation measured with the MTT colorimetric test, cell cycle phase, and on lipidic peroxidation (free radical production). RESULTS: The results indicate that laser irradiation to DBMSC did not change the morphology of the cells, but significantly increased their viability and the number of cells at the G2/M phase with 6, 10, and 12 J/cm(2). On the other hand, malonaldehyde production was significantly enhanced with 8 J/cm(2). CONCLUSIONS: The parameters used to irradiate DBMSC increased significantly proliferation without producing high levels of reactive oxygen species (ROS).

Effects of polyethylene and alpha-alumina particles on IL-6 expression and secretion in primary cultures of human osteoblastic cells.

The effect of two biomaterials, polyethylene and alpha-alumina, on interleukin-6 (IL-6) secretion and expression has been studied in human osteoblasts in primary culture. Human osteoblastic cells were derived from fresh trabecular bone explants removed during total knee arthroplasty. On reaching confluence, cells were subcultured in 6 well plates; the resulting subcultures were incubated until confluence and polyethylene or alpha-alumina particles were added to some while the rest were left as controls. The IL-6 mRNA levels were assessed by reverse transcription (RT) followed by polymerase chain reaction (PCR). IL-6 secretion was measured in the conditioned medium. The IL-6 expression was higher in the presence of both biomaterials. Maximum expression occurred in response to a dose of 50 mg particles well with both biomaterials and was greater after polyethylene particle addition than after alpha-alumina particle addition at this dose. The maximum IL-6 secretion elicited by alpha-alumina was produced at 10 mg particles well while maximum response with polyethylene required 50 mg well. At a dose of 10 mg/well, alpha-alumina particles induced more secretion than 10 mg of polyethylene particles. Nevertheless, at a dose of 50 mg/well maximum secretion was produced with polyethylene particles. In conclusion and in our experimental conditions, polyethylene as well as alpha-alumina increased both the expression and the secretion of IL-6 in human osteoblastic cells in primary culture and stimulation from polyethylene appears stronger than that from alpha-alumina at the same dose.

Effects of MA 956 superalloy and alpha-alumina particles on some markers of human osteoblastic cells in primary culture.

One of the problems associated with the modern biomaterials used in prostheses is osteolysis, which, although its exact origin is unknown, has been associated with wear particles. Osteoblasts seem to participate directly in this phenomenon. This paper investigates in vitro cellular response to the wear particles from the metal substrate and ceramic covering (alpha-alumina) of a new titanium yttrium aluminum alloy, MA 956, that has been proposed as a biomaterial because of its exceptional mechanical and electrochemical properties. The effect of different sizes (10 and 80 microm) of MA 956 and alpha-alumina particles on osteoblast function was studied in primary human bone cell cultures. Cells were harvested from trabecular bone fragments obtained during knee arthroplasty. Osteoblastic cell response to the particles was measured by assaying C-terminal type I procollagen (PICP), alkaline phosphatase, and osteocalcin secretion, with and without 1.25(OH)(2)D(3) stimulation, in the cell-conditioned medium. Both sizes of MA 956 and alpha-alumina particles decreased PICP secretion in nonstimulated osteoblastic cells, but this secretion was not affected in the cultures stimulated with 1.25(OH)(2)D(3). Only the 10 microm alpha-alumina particles inhibited alkaline phosphatase activity in 1.25(OH)(2)D(3)-stimulated and nonstimulated cultures. The rise in osteocalcin levels after 1.25(OH)(2)D(3) stimulation was lower in the presence of the 10 microm MA 956 particles than in the presence of alpha-alumina particles. Although both materials seem to have directly affected in vitro osteoblastic cell function, the increase in osteocalcin levels after 1.25(OH)(2)D(3) stimulation was lower after exposure to MA 956 particles than the increase observed after exposure to alpha-alumina particles. Therefore, it does not seem that osteocalcin stimulated bone resorption, suggesting that MA 956 would be less likely to provoke osteolysis.