Effects of Nd:YAG laser irradiation on cultured human gingival fibroblasts

Assessment of Human Gingival Fibroblast Proliferation after Laser Stimulation In Vitro Using Different Laser Types and Wavelengths (1064, 980, 635, 450, and 405 nm)-Preliminary Report

Purpose: to assess the effect of photobiomodulation (PBM) on human gingival fibroblast proliferation. Methods: The study was conducted using the primary cell cultures of human fibroblasts collected from systemically healthy donors. Three different laser types, Nd:YAG (1064 nm), infrared diode laser (980 nm), and prototype led laser emitting 405, 450, and 635 nm were used to irradiate the fibroblasts. Due to the patented structure of that laser, it was possible to irradiate fibroblasts with a beam combining two or three wavelengths. The energy density was 3 J/cm², 25 J/cm², 64 J/cm². The viability and proliferation of cells were determined using the (Thiazolyl Blue Tetrazolium Blue) (MTT) test conducted 24, 48, and 72 h after laser irradiation. Results: The highest percentage of mitochondrial activity (MA = 122.1%) was observed in the group irradiated with the 635 nm laser, with an energy density of 64 J/cm² after 48 h. The lowest percentage of MA (94.0%) was observed in the group simultaneously irradiated with three wavelengths (405 + 450 + 635 nm). The use of the 405 nm laser at 25 J/cm² gave similar results to the 635 nm laser. Conclusions: The application of the 635 nm and 405 nm irradiation caused a statistically significant increase in the proliferation of gingival fibroblasts.

Effects of high power-pulsed Nd:YAG laser irradiation on the release of transforming growth factor-beta (TGF-β) and vascular endothelial growth factor (VEGF) from human gingival fibroblasts

The purpose of this study was to investigate the effect of different high-power energy settings of a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (1064 nm) on cell viability of human gingival fibroblasts (GFs) and release of transforming growth factor-beta (TGF-β) and vascular endothelial growth factor (VEGF) on these cells. GFs were isolated from human gingival connective tissues during the crown lengthening procedure. GFs were irradiated with different laser parameters as follows: group 1: 1 W (100 mJ, 10 Hz) 10 seconds; group 2: 1.5 W (150 mJ, 10 Hz) 10 seconds; group 3: 2 W (200 mJ, 10 Hz) 10 seconds; group 4: 1 W (100 mJ, 10 Hz) 20 seconds; group 5: 1.5 W (150 mJ, 10 Hz) 20 seconds; and group 6: 2 W (200 mJ, 10 Hz) 20 seconds. Cell viability/cell proliferation was analyzed with XTT (tetrazolium salt, cell proliferation kit) staining. The release levels of TGF-β and VEGF were analyzed by the enzyme-linked immunosorbent assay. No significant differences were observed in the different laser irradiation groups compared to the control group in terms of cell viability (p > 0.05). The release of TGF-β was not affected by different laser irradiation settings (p > 0.05). Only group 6 promoted significantly higher VEGF release from GFs in 24 hours compared to the control group (p ˂ 0.05). These findings suggest that high-power Nd:YAG laser is probably safe but has a very limited effect for wound healing.

Evaluation effect of low level Helium-Neon laser and Iranian propolis extract on Collagen Type I gene expression by human gingival fibroblasts: an in vitro study

BACK GROUND AND AIM

production of collagen by fibroblast cells is a key component in wound healing. Several studies have shown that low level laser therapy (LLLT) and propolis extract stimulate collagen Type I production. The aim of this study is to evaluation the combined effect of LLL helium neon (632.8 nm) and Iranian propolis extract on collagen Type I gene expression by human gingival fibroblasts (HGF3-PI 53).

METHODS AND MATERIALS

Human gingival fibroblasts after culturing divided into six experimental groups: G1-control group, which received no irradiation and propolis extract, G2-irradiated at1.5 J/cm², G3-irradiated at 0.15 J/cm², G4-recived extract of propolis, G5- combined extract of propolis and 1.5 J/cm² laser irradiation and G6- combined extract of propolis and 0.15 J/cm² laser irradiation. The experiments were conducted in triplicate. After 24 hour, the total RNA was extracted and cDNA synthesis was performed. Type I collagen mRNA expression was determined with real time PCR.

RESULTS

The obtained results illustrated a statistically significant difference between G3 (0.15 J/cm²) and G1 (control group) in levels of collagen Type I messenger RNA (mRNA) expression (p<0.05). The irradiated cells showed a 1.4 times increase in mRNA expression of the collagen Type I gene. Expression of this gene decreases in other groups that this difference was statistically significant.

CONCLUSION

LLLT in different dosage and propolis extract may result in decreased or increased collagen type I gene expression. However this effect should be investigated in clinical studies.

Effect of Nd:YAG Low Level Laser Therapy on Human Gingival Fibroblasts

Aim. To evaluate the effect of Low Level Laser Therapy (LLLT) on human gingival fibroblasts in terms of proliferation and growth factors' secretion (EGF, bFGF, and VEGF). Materials and Methods. Primary cultures of keratinized mucosa fibroblasts were irradiated by a Nd:YAG laser 1064 nm with the following energy densities: 2.6 J/cm², 5.3 J/cm², 7.9 J/cm², and 15.8 J/cm². Controls were not irradiated. Cultures were examined for cell proliferation and growth factors' secretion after 24, 48, and 72 hours. All experimental procedures were performed in duplicate. Data were analyzed by Student's t-test (p < 0.05). Results. All laser-irradiation doses applied promoted a higher cell proliferation at 48 hours in a dose-response relationship compared to controls. This difference reached statistical significance for the cultures receiving 15.8 J/cm² (p = 0.03). Regarding EGF, all laser irradiation doses applied promoted a higher secretion at 48 hours in a reverse dose-response pattern compared to controls. This difference reached statistical significance for the cultures receiving 2.6 J/cm² (p = 0.04). EGF levels at the other time points, bFGF, and VEGF showed a random variation between the groups. Conclusion. Within the limits of this study, LLLT (Nd:YAG) may induce gingival fibroblasts' proliferation and upregulate the secretion of EGF. Further studies are needed to confirm these results.

Effect of 1,064-nm Nd:YAG laser therapy on GCF IL-1β and MMP-8 levels in patients with chronic periodontitis

The aim of this study was to evaluate the long-term effects of a combined periodontal treatment of scaling and root planing (SRP) and Nd:YAG laser (NDL) in chronic periodontitis (CP) patients. This was accomplished by determining the periodontal indices and the interleukin-1beta (IL-1β) and matrix metalloproteinase-8 (MMP-8) levels of the gingival crevicular fluid (GCF). This study was performed according to a random split-mouth-design, controlled clinical trial for sulcular debridement on 40 teeth from 20 patients with generalized moderate chronic periodontitis. The periodontal healing outcomes were compared after periodontal treatment with either SRP + NDL at 1 W (test side) or SRP (control side). Plaque index (PI), gingival index (GI), probing pocket depth (PPD), and clinical attachment level (CAL) were recorded, and samples of gingival crevicular fluid (GCF) were taken at baseline and post-therapy (3 and 9 months after treatment). The GCF samples were analyzed for IL-1β and MMP-8. There was postoperative improvement of all clinical parameters in both groups, but test side GI, PPD, and CAL recovery was higher than that of the control side (p < 0.05). Although levels of IL-1β and MMP-8 in GCF after treatment were lower in the test side than the control side, there was not a statistically significant difference (p > 0.05). In the long term, we found that SRP + NDL treatment of periodontal pockets was more effective than SRP alone in reducing PPD, CAL, GI, and GCF values.

An experimental pathologic study of gingivectomy using dual-wavelength laser equipment with OPO

BACKGROUND AND OBJECTIVES

This study was conducted to evaluate how soft tissues respond to treatment by a tunable laser with an optical parametric oscillating (OPO) mechanism capable of simultaneously emitting two wavelengths.

MATERIALS AND METHODS

Marginal gingiva of dogs was incised by a prototype laser oscillator. The oscillator was set at two wavelengths known to effectively incise tissue and arrest hemorrhage with minimal invasiveness. Four laser irradiation conditions were set based on different combinations of the 1.67 and 2.94 microm wavelengths. The animals were sacrificed immediately after surgery, 7 days after surgery, and 28 days after surgery for histological examination.

RESULTS

When irradiation at 1.67 and 2.94 microm wavelengths was simultaneously applied, the former conferred an observable hemostatic effect and the latter incised the tissue. Wound healing was similar to that in conventional methods and no serious inflammation was observed.

CONCLUSION

Simultaneous irradiation at wavelengths of 1.67 and 2.94 microm can be an effective method in soft tissue surgery.

Photoradiation could influence the cytoskeleton organization and inhibit the survival of human hepatoma cells in vitro

Low-power laser therapy has become popular in clinical applications including promoting wound healing and pain relief. However, effects of this photoradiation on human hepatoma cells are rarely studied. Previously, we found 808 nm gallium aluminum arsenide (GaAlAs) continuous wave laser had an inhibitory effect on the proliferation of human hepatoma cell lines HepG2 and J-5 at the energy density of 5.85 and 11.7 J/cm(2), respectively. The aim of the present study was to evaluate the possible mechanism of action of this photoradiation on HepG2 and J-5 cells. HepG2 and J-5 cells were cultured in 24-well plates for 24 h. After photoradiation by 130 mW 808 nm GaAlAs continuous wave laser for different time intervals (0, 30, 60, 90, 120, 150, and 180 s), Western blot and immunofluorescent staining were used to examine the expression and distribution of histone and cytoskeletal proteins. The cell counts as well as histone and synemin expression of HepG2 and J-5 cells were reduced by photoradiation at the energy density of 5.85 and 11.7 J/cm(2), respectively. Furthermore, the architecture of cytoskeletons and the distribution of intermediate filament-associated proteins (plectin and synemin) were disorganized by photoradiation. Photoradiation by 808 nm GaAlAs continuous wave laser at the energy density of 5.85 and 7.8 J/cm(2) inhibited the survival of human hepatoma cell lines. The mechanism might reduce synthesis of histone and synemin. Reduced histone synthesis might further reduce the proliferation rate of these cells. Reduced synemin synthesis might result in the destruction of the cytoskeleton. Therefore, the net effects by this photoradiation were reduced cell survival.

Long-term effect of pulsed Nd:YAG laser irradiation on cultured human periodontal fibroblasts

BACKGROUND AND OBJECTIVES

The purpose of this study was to investigate the long-term effect of Nd:YAG laser irradiation on cultured human periodontal fibroblasts (hPF).

STUDY DESIGN/MATERIALS AND METHODS

The cultured hPF were irradiated by pulsed Nd:YAG laser. The power delivery was 50 mJ x 10 pps (pulse per second) with irradiation duration 60, 120, 180, or 240 seconds. The viability and collagen content of laser-irradiated hPF were assessed on day 5 after laser treatment. Light microscope and transmission electron microscope (TEM) were used to observe cytomorphological change. The irradiated hPF cultured in mineralizing medium for 28 days were examined by alizarin red S and Von Kossa stain.

RESULTS

The cellular viability and collagen content of hPF decreased after Nd:YAG laser irradiation. Cell damage was noted with retraction of cellular processes, loss of normal architecture, and lysis of some cells. However, survived hPF proliferated and migrated to the cell-debris-associated deposits. The electron-dense cytoplasm and amorphous organelles in laser-damaged cells was revealed by TEM. In vitro mineralization was demonstrated in the long-term laser-irradiated hPF cultured in mineralizing medium.

CONCLUSION

Nd:YAG laser irradiation induced partial loss of cellular viability and collagen content. The co-existence of viable cells and progressive degeneration of laser-damaged cells was associated with the in vitro mineralization of hPF.

Effect of Low-Level Er:YAG Laser Irradiation on Cultured Human Gingival Fibroblasts

BACKGROUND

Low-level laser irradiation has been reported to enhance wound healing. Activation of gingival fibroblasts (GF) has a potential for early wound healing in periodontal treatment. The present study aimed to investigate the direct effect of low-level Er:YAG laser irradiation on gingival fibroblasts proliferation in order to clarify the laser effect on healing.

METHODS

Cultured human gingival fibroblasts (hGF) were exposed to low-power, pulsed Er:YAG laser irradiation with different energy densities ranging from 1.68 to 5.0 J/cm(2). The cultures were analyzed by means of trypan blue staining and counted under a light microscope. The effect of Er:YAG laser on hGF was also evaluated using a transmission electron microscope (TEM).

RESULTS

Cultures irradiated with Er:YAG laser presented faster cell growth when compared with untreated controls. This difference was statistically significant. Transmission electron microscopy revealed rough endoplasmic reticulum, prominent Golgi complexes, and mitochondria after laser irradiation.

CONCLUSIONS

Our results showed that the low-level Er:YAG laser irradiation stimulates the proliferation of cultured gingival fibroblasts. The optimal stimulative energy density was found to be 3.37 J/cm(2). This result suggests that Er:YAG laser irradiation may be of therapeutic benefit for wound healing.

Chondrocyte damage following osteochondral grafting using metal and plastic punches: comparative study in an animal model

PURPOSE

Osteochondral impaction grafting to manage isolated chondral defects in femoral condyles usually uses a metal punch to impact the grafts into predrilled cavities. Damage to the chondrocytes during impaction is a concern, however, and new methods are being sought to minimise the damage. We studied if impaction with a plastic punch instead of a metal punch reduces the extent of chondrocyte damage in an animal model.

METHODS

32 osteochondral plugs were prepared from knees of 10 freshly slaughtered sheep knees; the contralateral condyles were then prepared to receive the osteochondral grafts. 20 plugs were impacted into predrilled holes: 10 using a metal punch and 10 using a plastic punch. The 12 remaining plugs were used as controls. The plugs were recovered, incubated for 24 hours in calf serum, and stained with 3-[4,5-dimethylthiazol]-2,5-diphenyltetrazolium to measure the content of viable cells. Digital photographs of the stained cartilage were then analysed on a 0-to-255 grey-scale.

RESULTS

We found no significant difference in the extent of chondrocyte damage caused by impaction using metal and plastic punches. The content of viable cells in plugs impacted by metal and plastic punches, however, was significantly lower than that in the control plugs, as reflected by higher means of light intensity of 52.9 (p<0.001) and 32.4 (p=0.005), respectively.

CONCLUSION

Impaction grafting clearly damages chondrocytes of the osteochondral plug. The use of a plastic punch does not reduce the extent of chondrocyte damage during the impaction grafting procedure.

Effect of short pulsed nonablative infrared laser irradiation on vascular cells in vitro and neointimal hyperplasia in a rabbit balloon injury model

BACKGROUND

Neointimal hyperplasia after PTCA is an important component of restenosis.

METHODS AND RESULTS

Cultures of rabbit endothelial cells and smooth muscle cells (SMCs) were irradiated with different doses of nonablative infrared (1064-nm) radiation. Normalized viability index detected with nondestructive Alamar Blue assay and direct cell count were studied. Our experiments demonstrated dose-dependent cytostatic or cytotoxic effects of laser irradiation. We also evaluated the long-term effect of endoluminal nonablative infrared laser irradiation on neointimal hyperplasia in a rabbit balloon injury model. PTCA of both iliac arteries of 23 New Zealand White rabbits was performed. One iliac artery was subjected to intra-arterial subablative infrared irradiation via a diffuse tip fiber. The contralateral vessel served as control. The diet was supplemented with 0.25% cholesterol and 2% peanut oil for 10 days before and 60 days after PTCA. Morphometry after 60 days showed that intimal areas were 0.76+/-0.18 and 1.85+/-0.30 mm(2) in the laser and control arteries, respectively (P=2.2x10(-11)).

CONCLUSIONS

We conclude that nonablative infrared laser inhibited neointimal hyperplasia after PTCA in cholesterol-fed rabbits for up to 60 days.