In vitro studies to evaluate the effect of varying culture conditions and IPL fluencies on tenocyte activities

Intense Pulsed Light Attenuates UV-Induced Hyperimmune Response and Pigmentation in Human Skin Cells

The skin of an organism is affected by various environmental factors and fights against aging stress via mechanical and biochemical responses. Photoaging induced by ultraviolet B (UVB) irradiation is common and is the most vital factor in the senescence phenotype of skin, and so, suppression of UVB stress-induced damage is critical. To lessen the UVB-induced hyperimmune response and hyperpigmentation, we investigated the ameliorative effects of intense pulsed light (IPL) treatment on the photoaged phenotype of skin cells. Normal human epidermal keratinocytes and human epidermal melanocytes were exposed to 20 mJ/cm² of UVB. After UVB irradiation, the cells were treated with green (525–530 nm) and yellow (585–592 nm) IPL at various time points prior to the harvest step. Subsequently, various signs of excessive immune response, including expression of proinflammatory and melanogenic genes and proteins, cellular oxidative stress level, and antioxidative enzyme activity, were examined. We found that IPL treatment reduced excessive cutaneous immune reactions by suppressing UVB-induced proinflammatory cytokine expression. IPL treatment prevented hyperpigmentation, and combined treatment with green and yellow IPL synergistically attenuated both processes. IPL treatment may exert protective effects against UVB injury in skin cells by attenuating inflammatory cytokine and melanogenic gene overexpression, possibly by reducing intracellular oxidative stress. IPL treatment also preserves antioxidative enzyme activity under UVB irradiation. This study suggests that IPL treatment is a useful strategy against photoaging, and provides evidence supporting clinical approaches with non-invasive light therapy.

In vitro tissue culture model validation-the influence of tissue culture components on IPL energy output

Intense pulsed light (IPL) has been used therapeutically in a number of clinical settings and has been shown to have a photobiomodulatory effect on connective tissue cells, such as those derived from skin and tendon. In vitro cell culture models are essential tools preclinically in investigating such treatment modalities, as they help in optimising parameters for successful treatment. However, as culture system components have been reported to absorb part of the irradiated energy, which in turn has a bearing on the amount of light reaching the cells, it is important to establish specific parameters for the particular in vitro model used. This study, therefore, investigates the effect of our tissue culture system components on the IPL energy delivered. Individual wells of multi-well plates were irradiated with IPL at different device settings and under variable culture conditions (e.g. in the absence or presence of cell culture media with or without the pH indicator dye, phenol red), and the energy lost through the culture system determined. Our data demonstrated that the IPL device delivered significantly lower outputs than those published, and energy absorption by the culture equipment would further reduce fluencies delivered to the cell monolayer. Furthermore, energy absorption by media containing phenol red was marginally greater than clear media and resulted in only a small increase in temperature, which would not be harmful to cells. The use of phenol red-containing media therefore is valid and physiologically relevant when examining light-culture system interactions.

Effect of light-emitting diodes, platelet-rich plasma, and their combination on the activity of sheep tenocytes

Healthy tendons play an important role in joint movements and subjected to a group of pathologies called tendinopathy due to multiple factors. Tendons have a slowly repairing process due to the low vascularity and cellularity. Treatment options aimed at potentiating the healing response and relieving symptoms. Phototherapy and platelet-rich plasma were novel treatment modalities in tendons based on photobiomodulation and growth factors during healing, and the results were encouraging suggesting calibrating treatment parameters. This study utilizes cell culture to explore the potential effect of light-emitting diode and/or growth factors in the form of platelet-rich plasma (PRP) on the activity of tenocytes isolated from sheep Achilles tendons by measuring the cell metabolism and cell mobility using cell viability and migration assays to proof safety and confirm activity. Results showed that sheep tenocyte-cultured groups treated with 5% platelet-rich plasma alone or combined with 4 J/cm² light-emitting diode have increased viability significantly when compared to control group after a 48 h, while light-emitting diode treatment has not decreased cell migration significantly when compared with control. Result suggests that using platelet-rich plasma alone or combined with light-emitting diode might have potential to enhance healing response at the conditions applied. PRP could enhance proliferation while LED could enhance migration and proliferation. Further research is needed at longer durations.