Influence of wavelength, power density and exposure time of laser radiation on chondrocyte cultures – An in-vitro investigation
ABSTRACT The influence of laser radiation on human osteoarthrotically changed chondrocytes was investigated using various wavelengths, power density and dependence on the exposure time in order to confirm the positive results obtained in an animal experiment. It was manifested that, if there was a specific parameter constellation (2 W; 16 W/cm2; 60 s; 120 J), an enhanced matrix synthesis (cartilage material from 36 patients) could be achieved. The proof succeeded by applying the radioisotope marking method (3H-proline).Interestingly enough it turned out that the application of too high a power density but constant energy density resulted in a reduced matrix synthesis rate (reduction of 28%). In this study, it was demonstrated for the first time that laser radiation may have a positive influence on human cartilage thus contributing to future in-vivo application.ZusammenfassungUntersucht wurde der Einfluss von Laserstrahlung verschiedener Wellenlänge, Leistungsdichte und die Abhängigkeit der Einwirkzeit auf humane, osteoarthrotisch veränderte Chondrozyten. Ziel war es, die im Tierexperiment gezeigten positiven Ergebnisse zu bestätigen. Es konnte dargelegt werden, dass bei Vorliegen einer bestimmten Parameterkonstellation (2 W; 16 W/cm2; 60 s; 120 J) bei einem Nd:YAG-Laser eine gesteigerte Matrixsynthese (Knorpelmaterial von 36 Patienten) erzielt wurde. Der Nachweis gelang mit der Methode der Radioisotopenmarkierung (3H-Prolin).Interessant war die Beobachtung, dass bei zu hoher Leistungsdichte, aber gleich bleibender Energiedichte eine verminderte Matrixsyntheserate (ca. 28%) resultiert.In dieser Arbeit wurde erstmals der mögliche positive Einfluss von Laserstrahlung auf humanen Knorpel bewiesen. Damit könnte eine erste Voraussetzung für die In-vivo-Anwendung gegeben sein.ResúmenSe estudió la influencia de la radiación láser en condrocitos humanos osteoartríticos usando diferentes longitudes de onda, densidades de potencia y tiempos de exposición, con el fin de confirmar los resultados positivos obtenidos en experimentos con animales. Se observó que utilizando un conjunto determinado de parámetros (2 W; 16 W/cm2; 60 s; 120 J) se obtiene un aumento en la síntesis de la matriz (material de cartílago proveniente de 36 pacientes). El éxito de la prueba se alcanzó aplicando el método de marcaje con radioisótopo (3H-prolina).Resultó interesante que, utilizando una densidad de potencia muy alta, pero una densidad de energía constante, se produjo una reducción de la tasa (28%) de síntesis de la matriz. En este trabajo se ha demostrado por primera vez que la radiación láser tendría una influencia positiva sobre el cartílago humano, pudiendo contribuir a futuras aplicaciones in vivo.
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ABSTRACT: Collagen metabolism in osteoarthritic human articular cartilage was compared to that in normal cartilage and was also correlated with the degree of severity of the osteoarthritic lesion as determined by a histological-histochemical grading system. No correlation was apparent between the concentrations of DNA, hydroxyproline, and hydroxylysine and the degree of severity of the osteoarthritic lesion (except in far-advanced lesions). Similarly, there was no correlation in levels of these components in tissues from the normal vs. osteoarthritic group. The similarity of the values of the ratio hydroxylysine/hydroxyproline in osteoarthritic tissue compared with normal, and the lack of variation in these with increasing severity of the disease process argues against the possibility that osteoarthritis is associated with a major shift in the synthesis of type II collagen to type I. [3H]Proline incorporation into osteoarthritic cartilage was increased fourfold as compared to normal cartilage and varied with advancing histological-histochemical grade. Measurement of the specific activity of insolubilized hydroxyproline-containing material of the cartilage matrix, as an index of the turnover of collagen, showed a sixfold increase in osteoarthritic cartilage which also varied with grade. These data suggest that collagen synthesis in these tissues is substantially greater than in nonosteoarthritic tissues and varies directly with the severity of the disease process up to a point and then varies inversely as the lesion becomes more severe.Journal of Clinical Investigation 05/1977; 59(4):593-600. · 12.81 Impact Factor
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ABSTRACT: The purpose of the present study was to examine the effects of laser irradiation on the growth and development of fetal limb tissue. Day 14 fetal mouse limbs (n=168) were irradiated with gallium arsenide laser (904 nm, spot size=0.002 cm2, pulse duration=200 nanoseconds, peak power=30 mW) for 1 minute each day while being maintained in an organ culture system for 3 or 5 days at the following energy densities [O (control), 0.23, 1.37, 2.75, 3.66, and 4.58 J/cm2]. Computer image analysis of photographic images showed that there was a significant inhibition (P < 0.05) of new tissue growth after administration of lower energy densities of laser (0.23 and 1.37 J/cm2). These low-energy densities of laser irradiation also produced increased dermal cell number and collagen fiber thickness as assessed with qualitative histologic analysis of limb development by a blinded observer. Quantitative analysis of collagen distribution by color densitometric analysis of tissue sections stained with sirus red and fast green confirmed that there was a significantly greater (P < 0.05) amount of collagen present in the dermis of limbs treated with low-energy densities of laser (0.23 and 1.37 J/cm2). Laser irradiation directly affected the growth and development of day 14 fetal mouse limbs in an organ culture system.Lasers in Surgery and Medicine 01/1999; 24(4):285-95. · 2.46 Impact Factor
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ABSTRACT: Reports of laser energy applied to soft tissues in vitro and in vivo suggest both stimulation and inhibition of specific metabolic processes, depending on the type of laser, the energy density (ED) used, the mode of delivery, and type of tissue studied. An earlier in vitro study of Nd:YAG laser irradiation of articular cartilage indicated stimulation of both matrix and DNA synthesis for 6 days following laser exposure. In vivo reports on the ability of Nd:YAG laser energy to stimulate the healing of partial-thickness cartilage defects are conflicting. In the present study, a noncontact continuous-wave Nd:YAG laser beam of varying EDs was applied to full-thickness adult articular cartilage explants maintained in organ culture; the metabolic processes of chondrocyte DNA synthesis and matrix synthesis were followed over 2 weeks. For both canine and bovine cartilage, low-levels of laser energy (ED 51-127 J/cm2) stimulated matrix synthesis at 6-7 days following laser exposure, with a concomitant decrease in baseline DNA synthesis. By 12-14 days, however, these dose-dependent effects were no longer seen, with no significant differences from control noted for any of the laser energies studied. Histologic analysis of the cartilage explants following laser exposure showed no significant differences in cell number or morphology between sample and control groups; however, a decrease in matrix proteoglycan staining was seen in the highest laser energy group at all time points. These findings indicate that exposure to low-level noncontact Nd:YAG laser energy promotes a significant stimulation of cartilage matrix synthesis. However, a single exposure may not be sufficient to promote a sustained upregulation of cartilage metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)Arthroscopy The Journal of Arthroscopic and Related Surgery 02/1992; 8(1):36-43. · 3.10 Impact Factor