Plasma temperature during methylene blue/light treatment influences virus inactivation capacity and product quality.

BACKGROUND: Photodynamic treatment using methylene blue (MB) and visible light is in routine use for pathogen inactivation of human plasma in different countries. Ambient and product temperature conditions for human plasma during production may vary between production sites. The influence of different temperature conditions on virus inactivation capacity and plasma quality of the THERAFLEX MB-Plasma procedure was investigated in this study. METHODS: Plasma units equilibrated to 5 ± 2°C, room temperature (22 ± 2°C) or 30 ± 2°C were treated with MB/light and comparatively assessed for the inactivation capacity for three different viruses, concentrations of MB and its photoproducts, activity of various plasma coagulation factors and clotting time. RESULTS: Reduced solubility of the MB pill was observed at 5 ± 2°C. Photocatalytic degradation of MB increased with increasing temperature, and the greatest formation of photoproducts (mainly azure B) occurred at 30 ± 2°C. Inactivation of suid herpesvirus, bovine viral diarrhoea virus and vesicular stomatitis virus was significantly lower at 5 ± 2°C than at higher temperatures. MB/light treatment affected clotting times and the activity of almost all investigated plasma proteins. Factor VIII (-17·7 ± 8·3%, 22 ± 2°C) and fibrinogen (-14·4 ± 16·4%, 22 ± 2°C) showed the highest decreases in activity. Increasing plasma temperatures resulted in greater changes in clotting time and higher losses of plasma coagulation factor activity. CONCLUSIONS: Temperature conditions for THERAFLEX MB-Plasma treatment must be carefully controlled to assure uniform quality of pathogen-reduced plasma in routine production. Inactivation of cooled plasma is not recommended.

Effect of increased agitation speed on pathogen inactivation efficacy and in vitro quality in UVC-treated platelet concentrates.

BACKGROUND AND OBJECTIVES: Pathogen inactivation technologies require continuous development for adjustment to different blood components and products. With Theraflex UV-Platelets, a system using shortwave ultraviolet C (UVC) light (254 nm), efficient mixing of platelet concentrates (PCs) during UVC treatment is essential to ensure homogeneous illumination of the blood components. In this study, we investigated the impact of increasing the agitation speed during UVC treatment on pathogen inactivation capacity and platelet quality. MATERIAL AND METHODS: The pathogen inactivation efficacy of UVC treatment was evaluated at two agitation speeds (110 vs. 180 rpm) using four different transfusion-relevant bacteria strains and three model viruses. Using a pool-and-split design, the in vitro quality of buffy coat-derived PCs stored in SSP+ additive solution for up to 7 days was assessed in UVC-treated PCs agitated at either 110 rpm (standard speed) or 180 rpm (increased speed) and in untreated controls. RESULTS: The higher agitation speed improved bacterial inactivation but did not influence viral inactivation. Metabolic activity (glucose consumption and lactate accumulation) in UVC-treated platelets was slightly higher than in untreated controls. Increases in parameters such as CD62P expression and annexin A5 binding indicated moderate activation of UVC-treated platelets. Quality variables for UVC-treated platelets agitated at standard vs. increased agitation speed were comparable. CONCLUSION: The mixing rate during illumination may be a process parameter for further development of UVC-based pathogen inactivation procedures for PLT concentrates.

Challenge study of the pathogen reduction capacity of the THERAFLEX MB-Plasma technology.

BACKGROUND AND OBJECTIVES: Although most pathogen reduction systems for plasma primarily target viruses, bacterial contamination may also occur. This study aimed to investigate the bacterial reduction capacity of a methylene blue (MB) treatment process and its virus inactivation capacity in lipaemic plasma. MATERIALS AND METHODS: Bacterial concentrations in plasma units spiked with different bacterial strains were measured before and after the following steps of the THERAFLEX MB-Plasma procedure: leucocyte filtration, MB/light treatment and MB filtration. Virus inactivation was investigated for three virus types in non-lipaemic, borderline lipaemic and highly lipaemic plasma. RESULTS: Leucocyte filtration alone efficiently eliminated most of the tested bacteria by more than 4 logs (Staphylococcus epidermidis and Staphylococcus aureus) or to the limit of detection (LOD) (≥ 4.8 logs; Escherichia coli, Bacillus cereus and Klebsiella pneumoniae). MB/light and MB filtration further reduced Staphylococcus epidermidis and Staphylococcus aureus to below the LOD. The small bacterium Brevundimonas diminuta was reduced by 1.7 logs by leucocyte filtration alone, and to below the LOD by additional MB/light treatment and MB filtration (≥ 3.7 logs). Suid herpesvirus 1, bovine viral diarrhoea virus and human immunodeficiency virus 1 were efficiently inactivated by THERAFLEX MB-Plasma, independent of the degree of lipaemia. CONCLUSION: THERAFLEX MB-Plasma efficiently reduces bacteria, mainly via the integrated filtration system. Its virus inactivation capacity is sufficient to compensate for reduced light transparency due to lipaemia.

Laser assisted skin closure (LASC) by using a 815-nm diode-laser system accelerates and improves wound healing.

BACKGROUND AND OBJECTIVE: This study aimed to evaluate a 815-nm diode-laser system to assist wound closure to accelerate and improve healing process. STUDY DESIGN/MATERIALS AND METHODS: A total of 25 male hairless rats (mutant OFA Sprague-Dawley rats, IFFA-CREDO, L'Arbresle, France) with four dorsal skin incisions were used for the study. For each wound, the good apposition of the edges was obtained with buried absorbable suture. In the laser group, the laser beam was applied spot by spot through a transparent adhesive dressing along two incisions with the following parameters: 1.5 W; 3 seconds; spot diameter, 2 mm; fluence, 145 J/cm(2). Both control wounds were closed with conventional suture techniques. The duration of the closure procedure was noted for each group. Clinical examination, histologic study, and measurement of tensile strength were performed at 3, 7, 15, and 21 days after surgery. Determination of activation of heat shock protein 70 (Hsp70) through immunocytochemistry was performed at days 1 and 7. RESULTS: LASC was 4 times faster to process than conventional suture: 1 minute 49 +/- 20.6 seconds vs. 7 minutes 26 +/- 62.2 seconds. In the laser group, healing was accelerated resulting in a more indiscernible scar than in the control groups. Histologic aspect was better with earlier continuous epidermis and dermis and a thinner resulting scar. Tensile strength was 30 to 58% greater than in control groups at 7 and 15 days (P < 0.001). Expression of Hsp70 was markedly induced in skin structures examined after laser exposure. CONCLUSIONS: This study shows the ability of the 815-nm diode-laser system to assist wound closure leading to an acceleration and an improvement of wound healing with indiscernible resulting scar. The mechanisms of this phenomenon are still unclear but further investigations are in progress to attempt to explain them.

Laser skin resurfacing using a frequency doubled Nd:YAG laser after topical application of an exogenous chromophore.

BACKGROUND AND OBJECTIVES: Although laser skin resurfacing performed with CO(2) or Er:YAG lasers is efficient, side effects such as prolonged postoperative erythema, delayed healing, scarring, and pigmentation, have been reported. These side effects are due to skin characteristics but also to variations of the thermal effects associated with laser skin resurfacing. The study aimed to evaluate a new laser resurfacing method based on a previous topical application of an exogenous chromophore in order to have reproducible thermal effects. MATERIALS AND METHODS: Exogenous chromophore consisted in carbon dispersed and mixed with film-forming polymers and water. The resultant solution was applied to the skin surface using an airbrush. Experimental evaluation was performed in vivo on hairless rat skin using the following parameters (532 nm, 2.7 W, 1 mm, 50-200 ms, 17.2-68.8 J/cm(2), single pass). Skin biopsies were taken to evaluate histological changes and to quantify epidermis ablation and dermal coagulation depth. Wound healing was followed up during 10 days. RESULTS: Total epidermis ablation was achieved with all pulse durations used. Dermal coagulation depth increased as a function of exposure time. Scar formation was correlated with dermal coagulation depth. CONCLUSION: The concept of applying a carbon-based solution onto skin in order to obtain laser light conversion into heat followed by heat transfer to the tissue is valid for laser skin resurfacing. By selecting exposure time, the thermal effects are predictable and dermal coagulation depth can be either that observed with a Er:YAG laser or that obtained with a CO(2) laser. Moreover, frequency doubled Nd:YAG laser, already used in dermatology for angiodysplasias treatment, could be easily used for resurfacing of periorbital or perioral zones.

A new method to improve penetration depth of dyes into the follicular duct: potential application for laser hair removal.

BACKGROUND: Many persons seek to decrease hair growth and hair density. Although a variety of epilating methods are available, a practical and permanent hair removal treatment is needed. OBJECTIVE: The purpose of this study was to evaluate a new method of obtaining a better penetration depth of dyes into the follicular duct. By increasing both the quantity and the penetration depth of dye into the follicular duct, the efficacy of laser hair removal could be improved. METHODS: Dye penetration depth was assessed histologically after the use of formulations containing rhodamine-6G-loaded microspheres dispersed into two different silicones. Each formulation was tested on two hairless rats. After formulation application, dye diffusion was realized by applying ethanol on the skin to extract rhodamine-6G from microspheres. RESULTS: In all our experimental conditions follicular targeting occurred. No difference in the penetration depth of rhodamine-loaded microspheres was seen between our different silicone formulations. After ethanol application, the penetration of rhodamine-6G into the hair follicle was considerably increased by the fluid silicone vehicle (vs volatile silicone). CONCLUSION: This new galenical approach aims to transport a dye into the hair follicle specifically and deeply. By using adequate laser, the efficiency of laser hair removal could be increased.

A preliminary clinical and histopathological study of laser skin resurfacing using a frequency-doubled Nd:YAG laser after application of Chromofilm.

BACKGROUND AND OBJECTIVES: Carbon dioxide (CO2) and Er:YAG lasers are commonly used for laser skin resurfacing. In demonstrating their efficacy, intra- and interoperator variability may be important. In attempting to solve this problem, a new concept was developed which combines a previous application of an exogenous chromophore onto the skin in a standardized way (Chromofilm) and irradiation with a millisecond, low-power pulsed laser. MATERIALS AND METHODS: This study aimed to evaluate this new concept in vivo in human skin using a 532-nm Nd:YAG laser connected to a scanner using the following parameters: 532 nm, 2W, 1-mm spot size, 30-mm2 hexagonal surface irradiation and 50-120-ms pulse duration. The laser irradiation was performed both 15 h and 1 h prior to the facelift procedure. Tissue samples were examined histologically to determine the injury depth using nitroblue-tetrazolium chloride (NBTC) staining, haematoxylin-eosin staining and Masson's staining. RESULTS: Morphometric analysis of histological preparations showed that the depth of injury was dose-dependent: 50-ms pulse duration induced total epidermis ablation and fine dermal coagulation; 120-ms pulse duration induced dermal coagulation down to 120 microns. No residual carbon film was observed on histologic sections. CONCLUSION: Laser skin resurfacing using a 532-nm laser irradiation after application of a carbon film transfer is an effective method for skin resurfacing. With this new galenic approach (Chromofilm), the control of all parameters (thickness, chromophore concentration and distribution) can be achieved to predict the thermal injury obtained after laser irradiation.