Can thermal lasers promote skin wound healing?

Laser-assisted cartilage reshaping (LACR) for treating ear protrusions: a clinical study in 24 patients

BACKGROUND

Protruding ears are the most common congenital ear deformity, with a frequency of 13.5%. Since 1845 and the first works of Dieffenbach, over 170 classical surgical methods have been proposed to correct it. We introduced laser-assisted cartilage reshaping (LACR) in 2004 as an alternative to invasive surgical otoplasty.

METHODS

Between January 2008 and June 2008, 24 patients underwent LACR for treatment of bilateral ear protrusion. Fourteen adults and ten children were treated (mean age = 16.0 years, range = 6-45 years). No anesthesia was used. Both sides of the entire helix and the concha were irradiated using a 1540-nm laser connected to a 4-mm spot handpiece with integrated cooling. Fluences varying from 70 up to 84 J/cm(2) were applied. Immediately after the irradiation, silicone elastomer was inserted inside the helix to give it the desired shape. After 3 minutes a solid mold was obtained. Patients were asked to keep this mold in place at all times with a bandage wrapped around the head for the first 3 weeks and then for an additional 3 weeks only during the night. A non-steroidal anti-inflammatory drug (NSAID) was prescribed to the patients for 3 days. At 1, 30, 60, and 90 days after the procedure, ears were checked and photographs were taken. Clinical follow-up at 1 year was obtained via direct patient contact or over the telephone.

RESULTS

The treatment was well tolerated. No hematomas or skin necrosis occurred. Contact dermatitis was observed in four children and two adults as a result of inappropriate mold design. These patients stopped wearing the mold and the shape of their ear did not improve. For the remaining 18 patients (6 children and 9 adults), the expected ear reshaping was obtained (fluence was 84 J/cm(2)). For three other adults, incomplete reshaping of the ears was observed and can be correlated to a lower fluence (70 J/cm(2)).

CONCLUSION

LACR, performed without any anesthesia, is a safe and less morbid approach to surgical otoplasty.

Laser-assisted skin healing (LASH) in hypertrophic scar revision

Laser-Assisted Skin Healing (LASH) is based on the therapeutic effects of controlled thermal post-conditioning. The authors have previously demonstrated on humans that an 810-nm diode-laser system could assist wound closure leading to an improvement of wound healing with a resulting indiscernible scar. A 47-year-old woman (skin type II), who developed systematically hypertrophic scars after surgery, was enrolled for a hypertrophic scar revision. Excess scar tissue was removed. Immediately after the conventional closure of the incision, laser irradiation (120 J/cm(2)) using a 0.8 cm(2) spot size (rectangular spot, length = 20 mm, width = 4 mm) was applied. Topical silicone gel sheeting (Cerederm((R))) was applied for 2 months afterwards to prevent a thick scar from reforming. No complications occurred during the course of this study. No recurrence of hypertrophic scarring was noticed 6 months after scar revision. This study reports, for the first time, the possibility of improving the appearance of hypertrophic scarring in scar revision by altering through thermal stress the wound-healing process. Since the appropriate initial management of wounds is of importance, the LASH technique could be offered as a new approach to prevent hypertrophic scarring.

Immunohistochemical investigation of wound healing in response to fractional photothermolysis

Despite growing clinical evidence of ablative fractional photothermolysis (AFP), little is known about the spatiotemporal molecular changes within the targeted compartments. Six subjects received three different single AFP treatments using a scanned 250 mum CO(2)-laser beam. Spatiotemporal changes of skin regeneration were estimated by immunohistochemical investigation (HSP70, HSP72, HSP47, TGFbeta, procollagen III, CD3, CD20, and CD68) in skin samples 1 h, 3 days, and 14 days postintervention. The remodeling was uniformly started by regrowth of the epidermal compartment followed by partial to complete replacement of the microscopic ablation zones (MAZ) by newly synthesized condensed procollagen III. From day 3 to 14, the number of macrophages as well as giant cells surrounding the MAZ increased. TGFbeta expression was highest 1 h to 3 days following AFP. HSP70 and HSP72 expressions were highest 3-14 days postintervention in the spinocellular layer leading to an upregulation of HSP47. AFP performed by a scanned CO(2)-laser results in an early epidermal remodeling, which is followed by a dermal remodeling leading to a replacement of the MAZ with newly synthesized (pro)-collagen. During this, an inflammatory infiltrate with CD3(+) and CD20(+) cells surrounds the MAZ. The count of macrophages and giant cells involved in the replacement of the necrotic zones seems to be crucial for wound healing.

Laser-induced hyperthermia for treatment of granulation tissue growth in rats

OBJECTIVE

We aimed to develop a new technique for treatment of granulation tissue (GT) growth using local hyperthermia.

METHODS

A temperature-controlled diode laser system was developed for induction of mild hyperthermia in real time. GT was generated by harvesting the skin over the gluteal fascia in rats. Histopathological analysis was used to estimate the effect of hyperthermia on the tissue.

RESULTS

In untreated rats, GT was detected within 3 days and reached maximal thickness after 12 days. Hyperthermia at 43 degrees C and above significantly decreased GT thickness (n = 8 per group). Hyperthermia at 48 degrees C for 3 minutes was the most efficient parameter for treatment of GT (51% reduction), with minimal (5%) muscle necrosis.

CONCLUSIONS

Hyperthermia can significantly inhibit GT growth, with minimal damage to surrounding structures. Our findings suggest a possible role for hyperthermia as a therapeutic model against GT. Further research and long-term studies are needed to explore the utility of laser-induced hyperthermia for inhibition of GT growth.

Role of HSP70 in cellular thermotolerance

BACKGROUND AND OBJECTIVE

Thermal pretreatment has been shown to condition tissue to a more severe secondary heat stress. In this research we examined the particular contribution of heat shock protein 70 (HSP70) in thermal preconditioning.

STUDY DESIGN/MATERIALS AND METHODS

For optimization of preshock exposures, a bioluminescent Hsp70-luciferase reporter system in NIH3T3 cells tracked the activation of the Hsp70 gene. Cells in 96-well plates were pretreated in a 43 degrees C water bath for 30 minutes, followed 4 hours later with a severe heat shock at 45 degrees C for 50 minutes. Bioluminescence was measured at 2, 4, 6, 8, and 10 hours after preshock only (PS) and at 4 hours after preshock with heatshock (PS+HS). Viability was assessed 48 hours later with a fluorescent viability dye. Preshock induced thermotolerance was then evaluated in hsp70-containing Murine Embryo Fibroblast (+/+) cells and Hsp70-deficient MEF cells (-/-) through an Arrhenius damage model across varying temperatures (44.5-46 degrees C).

RESULTS

A time gap of 4 hours between preconditioning and the thermal insult was shown to be the most effective for thermotolerance with statistical confidence of P<0.05. The benefit of preshocking was largely abrogated in Hsp70-deficient cells. The Arrhenius data showed that preshocking leads to increases in the activation energies, E(a), and increases in frequency factors, A. The frequency factor increase was significantly greater in Hsp70-deficient cells.

CONCLUSION

The data shows that HSP70 contributes significantly to cellular thermotolerance but there are other pathways that provide residual thermotolerance in cells deficient in Hsp70.

Remodeling of the rat gingiva induced by CO2 laser coagulation mode

BACKGROUND AND OBJECTIVES

This study was conducted to clarify the morphologic characteristics and subsequent repair process of coagulation necrosis produced by pulsed CO(2) laser irradiation with relatively low fluence, and thereby to evaluate the clinical efficacy of this irradiation mode.

STUDY DESIGN/MATERIALS AND METHODS

Wounding of rat gingiva to produce coagulation necrosis was done with a CO(2) laser with a fluence of 326 J/cm(2). The structural characteristics of the wound and subsequent repair process were examined by means of histology, immunohistochemistry, and electron microscopy.

RESULTS

At 6 hours after irradiation, the cells in the laser wound appeared histologically intact but had lost the immunoreactivity to antibodies against Hsp47 and exhibited various ultrastructural signs of cell death. This wound area was lined by Hsp70-positive cells. At 1-day post-irradiation, the uptake of BrdU rapidly increased in the adjacent epithelium and connective tissue. The re-epithelization commenced at 1 day and was completed by 7 days. The necrotic tissue gradually became integrated within the newly formed connective tissue and the original contour of the gingiva was retained during the repair process. The repair process of the laser-induced wound progressed more rapidly than that of a scalpel-made wound.

CONCLUSIONS

The present study suggests that the coagulation necrosis produced by the low fluence pulsed CO(2) laser does not disturb the repair process but promotes its steady progress and subsequent tissue remodeling. This laser mode will pave the way for more conservative and minimally invasive surgery for treating a wide variety of oral soft tissue disorders.

Prognostic factors influencing the patency of hemodialysis vascular access: literature review and novel therapeutic modality by far infrared therapy

In Taiwan, more than 85% of patients with end-stage renal disease undergo maintenance hemodialysis (HD). The native arteriovenous fistula (AVF) accounts for a prevalence of more than 80% of the vascular access in our patients. Some mechanical factors may affect the patency of hemodialysis vascular access, such as surgical skill, puncture technique and shear stress on the vascular endothelium. Several medical factors have also been identified to be associated with vascular access prognosis in HD patients, including stasis, hypercoagulability, endothelial cell injury, medications, red cell mass and genotype polymorphisms of transforming growth factor-beta1 and methylene tetrahydrofolate reductase. According to our previous study, AVF failure was associated with a longer dinucleotide (GT)n repeat (n > or = 30) in the promoter of the heme oxygenase-1 (HO-1) gene. Our recent study also demonstrated that far-infrared therapy, a noninvasive and convenient therapeutic modality, can improve access flow, inflammatory status and survival of the AVF in HD patients through both its thermal and non-thermal (endothelial-improving, anti-inflammatory, antiproliferative, antioxidative) effects by upregulating NF-E2-related factor-2-dependent HO-1 expression, leading to the inhibition of expression of E-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1.

Molecular imaging-assisted optimization of hsp70 expression during laser-induced thermal preconditioning for wound repair enhancement

Patients at risk for impaired healing may benefit from prophylactic measures aimed at improving wound repair. Several photonic devices claim to enhance repair by thermal and photochemical mechanisms. We hypothesized that laser-induced thermal preconditioning would enhance surgical wound healing that was correlated with hsp70 expression. Using a pulsed diode laser (lambda=1.85 microm, tau(p)=2 ms, 50 Hz, H=7.64 mJ cm(-2)), the skin of transgenic mice that contain an hsp70 promoter-driven luciferase was preconditioned 12 hours before surgical incisions were made. Laser protocols were optimized in vitro and in vivo using temperature, blood flow, and hsp70-mediated bioluminescence measurements as benchmarks. Biomechanical properties and histological parameters of wound healing were evaluated for up to 14 days. Bioluminescent imaging studies indicated that an optimized laser protocol increased hsp70 expression by 10-fold. Under these conditions, laser-preconditioned incisions were two times stronger than control wounds. Our data suggest that this molecular imaging approach provides a quantitative method for optimization of tissue preconditioning and that mild laser-induced heat shock may be a useful therapeutic intervention prior to surgery.

Effect of a new infrared light device (1100-1800 nm) on facial lifting

Laser skin resurfacing procedures can be classed into two categories - invasive and non-invasive. The last several decades have witnessed a host of advancements in ablative laser therapy and other ablative modalities for the rejuvenation of skin, including the CO(2) laser, the erbium : yttrium aluminum garnet laser, chemical peels, and dermabrasion. Despite the excellent results that can result from the practice of these techniques by experienced surgeons, the invasive nature of these devices is associated with inherent risks and patient discomfort. Therefore, much of the focus has been on non-ablative lasers and intense-pulsed light devices. We evaluated the efficacy and safety of treatment with the new infrared light device (1100-1800 nm), Titan, and assessed the degree of improvement associated with two-time laser treatments, as compared to one-time laser treatment.

Far infrared therapy inhibits vascular endothelial inflammation via the induction of heme oxygenase-1

OBJECTIVE

Survival of arteriovenous fistulas (AVFs) in hemodialysis patients is associated with both far infrared (FIR) therapy and length polymorphisms of the heme oxygenase-1 (HO-1) promoter. In this study, we evaluated whether there is an interaction between FIR radiation and HO-1 in regulating vascular inflammation.

METHODS AND RESULTS

Treatment of cultured human umbilical vein endothelial cells (ECs) with FIR radiation stimulated HO-1 protein, mRNA, and promoter activity. HO-1 induction was dependent on the activation of the antioxidant responsive element/NF-E2-related factor-2 complex, and was likely a consequence of heat stress. FIR radiation also inhibited tumor necrosis factor (TNF)-alpha-mediated expression of E-selectin, vascular cell adhesion molecule-1, intercellular cell adhesion molecule-1, monocyte chemoattractant protein-1, interleukin-8, and the cytokine-mediated adhesion of monocytes to ECs. The antiinflammatory action of FIR was mimicked by bilirubin, and was reversed by the HO inhibitor, tin protoporphyrin-IX, or by the selective knockdown of HO-1. Finally, the antiinflammatory effect of FIR was also observed in patients undergoing hemodialysis.

CONCLUSIONS

These results demonstrate that FIR therapy exerts a potent antiinflammatory effect via the induction of HO-1. The ability of FIR therapy to inhibit inflammation may play a critical role in preserving blood flow and patency of AVFs in hemodialysis patients.

The management of postacne scarring

BACKGROUND

Therapeutic intervention for postacne scarring has historically been limited by the considerable morbidity of most treatments for only marginal disease improvement. Within the past decade, however, a greater understanding of the pathogenesis of acne scarring has led to the development of techniques that offer more favorable risk-benefit profiles.

OBJECTIVE

The aims of this article are to highlight a number of newer techniques and to assign their appropriateness to particular grades of acne scarring.

MATERIALS AND METHODS

Current modalities are discussed as they relate to disease process and specific acne scar types. Techniques are presented in order of most effectual therapeutic interventions for defined grades of acne scarring. Acne scarring grades have been described previously in terms of disease load, severity, and lesion morphologies.

RESULTS

A comprehensive discussion of updated therapeutic techniques and their biologic rationales in the treatment of acne scarring is presented. These include targeted interventions of inflammatory and postinflammatory processes, angiogenesis, immunologic processes, dermal and subcutaneous fibrosis, hypertrophy, and keloid scarring.

DISCUSSION

A requirement for developing successful treatments for postacne scarring is a greater understanding of its pathogenesis, variability among afflicted individuals, and the inflammatory mediators and immunology of the scarring process. Many innovative techniques introduced in the past decade attempt to counteract these pathologic processes while keeping the procedural and postoperative risks to a minimum.

Pulsed dye laser: what's new in non-vascular lesions?

BACKGROUND AND OBJECTIVE

In dermatology, the pulsed dye laser (PDL) is the therapeutic instrument of choice for treating most superficial cutaneous vascular lesions. In addition, clinical experience over the last decade allowed us to treat patients with an ever increasing number of non-vascular indications. The purpose of this report is to summarize and critically appraise the scientific evidence that support the role of PDL in treating non-vascular skin lesions.

METHODS

A literature-based study has been conducted, including the review of publications over the period January 1995 to December 2006, using the Medline Database. We also included our own experience in managing non-vascular lesions with the PDL. Four sets of preoperative and postoperative photos are presented.

RESULTS

For viral skin lesions, PDL proved to be an alternative to other therapy options. This applies particularly to periungual warts and mollusca contagiosa. The mechanism of PDL with inflammatory dermatoses has not yet been elucidated. The effect seems to be better if there is a vascular component to the disease. With most of these indications (such as psoriasis and acne), PDL currently plays a rather minor or complementary role. Regarding collagen remodelling (hypertrophic scars, keloids, stretch marks, and skin rejuvenation), the question of whether a therapy makes sense or not has to be decided from case to case.

CONCLUSION

With PDL, it is possible to achieve good results with numerous, partly less well-known indications (i.e. lupus erythematosus). With other diseases, PDL has so far been considered to be a complementary therapy method or to be in an experimental state.

Tissue concentration of transforming growth factor beta1 and basic fibroblast growth factor in skin wounds created with a CO2 laser and scalpel: a comparative experimental study, using an animal model of skin resurfacing

Although a number of ablative-laser techniques based on CO(2) and Er: YAG laser devices have been successfully developed and used in the clinical setting, the bio-molecular processes influencing wound healing after exposure to laser energy are not well elucidated. In this study, we aim to assess the impact of the mechanism of injury on the secretion of transforming growth factor beta1 (TGF-beta1) and basic fibroblast growth factor (bFGF) in various stages of wound healing, in wounds created with a CO(2) laser and scalpel. Ten Wistar rats were used to determine the levels of growth factor proteins TGF-beta1 and bFGF after CO(2) laser- and scalpel-induced skin injury. Tissue was excised on day 0 for untreated skin (control sites), and on days 1, 10, 30, and 90 following laser and scalpel surgery. Specimens were processed for histopathological analysis and for determining the concentration of growth factors by a Western blot technique. The concentration of TGF-beta1 increased markedly, at day 1 postinjury, from a baseline of 130+/-16 mm(2) (mean surface area of blotted-protein lanes) to 261+/-23 mm(2) and 394+/-22 mm(2) for laser-inflicted injury and scalpel wounds, respectively; the latter values were found to differ significantly (p<0.001). The concentration of b-FGF on day 10 postinjury differed significantly (p<0.001) between the laser sites (553+/-45 mm(2)) and the corresponding scalpel sites (418+/-41 mm(2)). Laser energy alters local tissue secretion of TGF-beta1 and bFGF of skin injuries created with the CO(2) laser compared with wounds created with a scalpel. These differences might have an impact on various aspects of wound healing of skin injuries created by a laser.

Minimally invasive skin rejuvenation with Erbium: YAG laser used in thermal mode

BACKGROUND AND OBJECTIVES

To evaluate the efficacy and safety of a thermal mode Erbium:YAG laser several in-vivo morphological as well as clinical changes were monitored in a multi-center investigation.

STUDY DESIGN/MATERIALS AND METHODS

An Erbium:YAG laser was used at a thermal mode with sub-ablative fluences of 2.1 and 3.1 J/cm(2) with parallel air cooling to treat either periorbital, perioral rhytides or patients with post-traumatic or acne scars. Two treatments were applied 2 months apart, with follow-up at 1, 3, 6, and 12 months post-treatment. Photographs were taken before and at each follow-up visit and evaluated by three blinded independent reviewers. Histology and immunohistochemistry for pro-collagen expression were investigated. Optical coherence tomography (OCT) was performed before, and at 4, 14, and 28 days after single pass treatment with Erbium:YAG thermal pulses.

RESULTS

The improvement of rhytides at 1-3 months follow-up was graded as excellent in 19%, good in 19%, fair in 31%, and no improvement in 31%. At the 6- to 12-month follow-up, the improvement was excellent in 40%, good in 40%, fair in 20%, and no improvement in 0%. The improvement of scars at 3-6 months follow-up was graded as excellent in 50%, good in 25%, fair in 25%, and no improvement in 0%. Intra- and post-operative discomfort was described as mild by the patients. OCT, histological sections and immunohistochemistry demonstrated production of new collagen bundles.

CONCLUSIONS

Thermal Erbium:YAG pulses can induce collagen neogenesis, as proved by temperature elevation and morphological changes in the upper dermis. This leads clinically to visible and long lasting reduction of wrinkles and scars after applying multiple passes with minimal side-effects.

Immediate tight sealing of skin incisions using an innovative temperature-controlled laser soldering device: in vivo study in porcine skin

BACKGROUND

A feedback temperature-controlled laser soldering system (TCLS) was used for bonding skin incisions on the backs of pigs. The study was aimed: 1) to characterize the optimal soldering parameters, and 2) to compare the immediate and long-term wound healing outcomes with other wound closure modalities.

MATERIALS AND METHODS

A TCLS was used to bond the approximated wound margins of skin incisions on porcine backs. The reparative outcomes were evaluated macroscopically, microscopically, and immunohistochemically.

RESULTS

The optimal soldering temperature was found to be 65 degrees C and the operating time was significantly shorter than with suturing. The immediate tight sealing of the wound by the TCLS contributed to rapid, high quality wound healing in comparison to Dermabond or Histoacryl cyanoacrylate glues or standard suturing.

CONCLUSIONS

TCLS of incisions in porcine skin has numerous advantages, including rapid procedure and high quality reparative outcomes, over the common standard wound closure procedures. Further studies with a variety of skin lesions are needed before advocating this technique for clinical use.

Far-infrared therapy: a novel treatment to improve access blood flow and unassisted patency of arteriovenous fistula in hemodialysis patients

Vascular access malfunction, usually presenting with an inadequate access flow (Qa), is the leading cause of morbidity and hospitalization in hemodialysis (HD) patients. Many methods of thermal therapy have been tried for improving Qa but with limited effects. This randomized trial was designed to evaluate the effect of far-infrared (FIR) therapy on access flow and patency of the native arteriovenous fistula (AVF). A total of 145 HD patients were enrolled with 73 in the control group and 72 in the FIR group. A WS TY101 FIR emitter was used for 40 min, and hemodynamic parameters were measured by the Transonic HD(02) monitor during HD. The Qa(1)/Qa(2) and Qa(3)/Qa(4) were defined as the Qa measured at the beginning/at 40 min later in the HD session before the initiation and at the end of the study, respectively. The incremental change of Qa in the single HD session with FIR therapy was significantly higher than that without FIR therapy (13.2 +/- 114.7 versus -33.4 +/- 132.3 ml/min; P = 0.021). In comparison with control subjects, patients who received FIR therapy for 1 yr had (1) a lower incidence (12.5 versus 30.1%; P < 0.01) and relative incidence (one episode per 67.7 versus one episode per 26.7 patient-months; P = 0.03) of AVF malfunction; (2) higher values of the following parameters, including Delta(Qa(4) - Qa(3)) (36.2 +/- 82.4 versus -12.7 +/- 153.6 ml/min; P = 0.027), Delta(Qa(3) - Qa(1)) (36.3 +/- 166.2 versus -51.7 +/- 283.1 ml/min; P = 0.035), Delta(Qa(4) - Qa(2)) (99.2 +/- 144.4 versus -47.5 +/- 244.5 ml/min; P < 0.001), and Delta(Qa(4) - Qa(2)) - Delta(Qa(3) - Qa(1)) (62.9 +/- 111.6 versus 4.1 +/- 184.5 ml/min; P = 0.032); and (3) a better unassisted patency of AVF (85.9 versus 67.6%; P < 0.01). In conclusion, FIR therapy, a noninvasive and convenient therapeutic modality, can improve Qa and survival of the AVF in HD patients through both its thermal and its nonthermal effects.

Effect of a laser irradiation on the vascularisation of safety and X-ray radiated bone

Thermal preconditioning induces a cytoprotective effect and promotes tissue recovering. Laser is an appropriated method to generate a controlled and reproducible heating. Bone healing, a crucial challenge in medicine, is affected by X-ray radiation which induces a chronic antiangiogenic effect. So, this study aims to investigate the role of laser preconditioning on the vascularisation of bone after X-ray radiation. An optical bone chamber allowed the study of the vascularization process. The vascular density (VD) was determined using image processing. A longitudinal study was performed on 20 rabbits divided in four groups: #1: control group (n=5); #2: laser irradiation alone (diode laser 810nm, fluence= 48J/cm2) (n=5). #3: X-ray radiation (18.75Gy) alone (n=5), #4: laser preconditioning 24 hours before a X-ray radiation (n=5). VD remained stable during 12-week follow up for groups #1 and #2. X-ray radiation lead to an important decrease of the superficial bone vascularization in group #3. The decrease of the vascularization was limited in group #4 highlighting a different evolution between group #3 and #4. Those results were confirmed by histological analysis. Our preliminary findings show that laser preconditioning preserves vascularization in X-ray radiated bone site, outlining a novel approach for the bone healing in which the vascular supply has been injured.

The effects of pulse energy variations on the dimensions of microscopic thermal treatment zones in nonablative fractional resurfacing

BACKGROUND AND OBJECTIVES

We examined the effects of pulse energy variations on the dimensions of microscopic thermal injury zones (MTZs) created on human skin ex vivo and in vivo using nonablative fractional resurfacing.

MATERIALS AND METHODS

A Fraxel SR laser system emitting at 1,550 nm provided an array of microscopic spots at variable densities. Pulse energies ranging from 4.5 to 40 mJ were tested on human abdominal skin ex vivo and in vivo. Tissue sections were stained with hematoxylin and eosin (H&E) or nitro blue tetrazolium chloride (NBTC) and MTZ dimensions were determined. Ex vivo and in vivo results were compared. Dosimetry analyses were made for the surface treatment coverage calculation as a function of pulse energy and collagen coagulation based on H&E stain or cell necrotic zone based on NBTC stain.

RESULTS

Each MTZ was identified by histological detection of a distinct region of loss of tissue birefringence and hyalinization, representing collagen denaturation and cell necrosis within the irradiated field immediately, 1, 3, and 7 days after treatment. At high pulse energies, the MTZ depth could exceed 1 mm and width approached 200 microm as assessed by H&E. NBTC staining revealed viable interlesional tissue. In general, no statistically significant difference was found between in vivo and ex vivo depth and width measurements.

CONCLUSIONS

The Fraxel SR laser system delivers pulses across a wide range of density and energy levels. We determined that increases in pulse energy led to increases in MTZ depth and width without compromising the structure or viability of interlesional tissue.

Heat shock proteins 47 and 70 expression in rodent skin model as a function of contact cooling temperature: Are we overcooling our target?

BACKGROUND AND OBJECTIVES

The degree of protective cooling required during laser therapy to achieve an optimal result is unknown. The expression of heat shock proteins, Hsp47 and Hsp70, were examined in the epidermis and dermis as biomarkers to quantify the degree and depth of tissue affected by non-ablative laser treatment using variable protective cooling parameters.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-one male Sprague-Dawley rats were treated with a 1,319 nm Nd:YAG laser using a sapphire cooling plate attached to the hand piece. A 4 cmx4 cm area on each side of the rat was treated with the same energy and pulse settings, with variable contact cooling. Protective cooling parameters, for each degree increment, ranging from 0 to 25 degrees C were studied. Immunohistochemistry (IHC), Western blot and PCR were performed to evaluate the effects of superficial cooling on Hsp47, and Hsp70 expressions.

RESULTS

Our data showed the extent of topical cooling needed to produce a thermal effect at different depths in the dermis, quantified by the expression of Hsp47 and Hsp70. Significant Hsp expression was observed with cooling of 13 degrees C and warmer; no identifiable cellular reaction was observed when cooling below 5 degrees C. There was no evidence of epidermal injury when treating the skin with any protective cooling ranging from 0 to 25 degrees C.

CONCLUSION

Our data would suggest contact cooling temperatures 5 degrees C and below completely protects through the entire dermis. There was no evidence of epidermal injury with protective cooling at any temperature between 0 and 25 degrees C. Warmer temperatures are safe and adequately protect the epidermis in this model.

Regulation of type I procollagen and MMP-1 expression after single or repeated exposure to infrared radiation in human skin

Human skin is daily exposed to infrared (IR) radiation from natural sunlight. However, the effects of IR irradiation on collagen metabolism have not been investigated in human skin in vivo. Here, we examined whether single or repeated (three times a week for 4 weeks) exposure to IR irradiation changes the expressions of type I procollagen and interstitial collagenase (MMP-1). By using immunostaining, Western blotting, and semi-quantitative RT-PCR, we analyzed the protein and mRNA levels of type I procollagen and MMP-1 in young buttock skin. A single dose of IR to human skin increased the expression of type I procollagen within 24h, but did not change the expression of MMP-1. On the other hand, multiple IR doses reduced the expression of type I procollagen and increased the expression of MMP-1. We also found that TGF-betas may mediate type I procollagen synthesis in IR-irradiated human skin. Our results demonstrate that the regulations of the expressions of type I procollagen and MMP-1 differ in acute and chronically IR-irradiated skin. In particular, decreased collagen levels and increased MMP-1 levels in chronic IR-irradiated skin may be associated with connective tissue damage. Thus, we suggest that repeated exposure to IR irradiation might induce premature skin aging (photoaging) in human skin in vivo.

Biological effect of far-infrared therapy on increasing skin microcirculation in rats

BACKGROUND/PURPOSE

Insufficient microcirculation of skin leads to acute and chronic tissue ischemia in cases of trauma, reconstructive surgery, diabetes mellitus and peripheral arterial occlusive disease. The autonomic nervous system and nitric oxide (NO) play important roles in maintaining blood perfusion of the skin. Far-infrared (FIR) therapy provides low energy of light emitted from an artificial radiator and has been used to treat many vascular-related disorders. Nevertheless, the mechanisms through which FIR works remain unclear. The present study aims to test the hypothesis that the effect of FIR is through increasing skin microcirculation by a mechanism other than its thermal effect.

METHODS

Sixty rats were used in the present study. A WS TY301 FIR emitter was placed 20 cm above the rats. Skin temperature and blood flow were continuously measured by a K-type thermocouple. Under laboratory control, the abdominal skin temperature steadily increased from 38-39 degrees C, and was kept at constant temperature. Skin microcirculation was measured with a continuous laser Doppler flowmeter.

RESULTS

There was no significant change of skin blood flow during FIR treatment. Skin blood flow increased significantly soon after the removal of the FIR emitter. The stimulating effect on skin blood flow was more significant in the rats treated with FIR for 45 min and could be sustained as long as 60 min. These findings suggested a non-thermic biological effect of FIR on skin microcirculation. The promotive effect of FIR on increasing skin blood flow was not influenced by pretreatment of APP (atropine, propranolol and phentolamine), but was suppressed by pretreatment with NG-nitro-L-arginine methyl ester (an endothelial nitric oxide synthase inhibitor).

CONCLUSION

In conclusion, FIR therapy exerts a NO-related biological effect to increase skin microcirculation in rats. This might bring into perspective the clinical application of FIR to treat ischemic disease by augmenting L-arginine/NO pathway.

Assessing laser-tissue damage with bioluminescent imaging

Effective medical laser procedures are achieved by selecting laser parameters that minimize undesirable tissue damage. Traditionally, human subjects, animal models, and monolayer cell cultures have been used to study wound healing, tissue damage, and cellular effects of laser radiation. Each of these models has significant limitations, and consequently, a novel skin model is needed. To this end, a highly reproducible human skin model that enables noninvasive and longitudinal studies of gene expression was sought. In this study, we present an organotypic raft model (engineered skin) used in combination with bioluminescent imaging (BLI) techniques. The efficacy of the raft model was validated and characterized by investigating the role of heat shock protein 70 (hsp70) as a sensitive marker of thermal damage. The raft model consists of human cells incorporated into an extracellular matrix. The raft cultures were transfected with an adenovirus containing a murine hsp70 promoter driving transcription of luciferase. The model enables quantitative analysis of spatiotemporal expression of proteins using BLI. Thermal stress was induced on the raft cultures by means of a constant temperature water bath or with a carbon dioxide (CO2) laser (lambda=10.6 microm, 0.679 to 2.262 Wcm2, cw, unfocused Gaussian beam, omegaL=4.5 mm, 1 min exposure). The bioluminescence was monitored noninvasively with an IVIS 100 Bioluminescent Imaging System. BLI indicated that peak hsp70 expression occurs 4 to 12 h after exposure to thermal stress. A minimum irradiance of 0.679 Wcm2 activated the hsp70 response, and a higher irradiance of 2.262 Wcm2 was associated with a severe reduction in hsp70 response due to tissue ablation. Reverse transcription polymerase chain reaction demonstrated that hsp70 mRNA levels increased with prolonged heating exposures. Enzyme-linked immunosorbent protein assays confirmed that luciferase was an accurate surrogate for hsp70 intracellular protein levels. Hematoxylin and eosin stains verified the presence of the thermally denatured tissue regions. Immunohistochemical analyses confirmed that maximal hsp70 expression occurred at a depth of 150 microm. Bioluminescent microscopy was employed to corroborate these findings. These results indicate that quantitative BLI in engineered tissue equivalents provides a powerful model that enables sequential gene expression studies. Such a model can be used as a high throughput screening platform for laser-tissue interaction studies.

Short-term clinical and microbiologic effects of pocket debridement with an Er:YAG laser during periodontal maintenance

BACKGROUND

The erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser is considered a useful tool for subgingival debridement because the laser treatment creates minimal damage to the root surface and has potential antimicrobial effects. The aim of this randomized controlled clinical trial was to evaluate clinical and microbiologic effects of pocket debridement using an Er:YAG laser in patients during periodontal maintenance.

METHODS

Twenty patients at a recall visit for maintenance were consecutively recruited if presenting at least four teeth with residual probing depth (PD) > or = 5 mm. Two pockets in each of two jaw quadrants were randomly assigned to subgingival debridement using 1) an Er:YAG laser (test) or 2) an ultrasonic scaler (control). The laser beam was set at 160 mJ with a pulse frequency of 10 Hz. Clinical variables were recorded at baseline, 1 month, and 4 months after treatment. Primary clinical outcome variables were changes in PD and clinical attachment level (CAL). Microbiologic analysis of subgingival samples was performed at baseline, 2 days, and 30 days after treatment using a checkerboard DNA-DNA hybridization technique against 12 periodontal disease-associated species.

RESULTS

The mean initial PD was 6.0 mm (SD: 1.2) in the test group and 5.8 mm (SD: 0.9) in the control group. At 1 month post-treatment, the PD reduction was significantly greater for test than control sites (0.9 versus 0.5 mm; P <0.05). The CAL gain also was significantly greater (0.5 versus 0.06 mm; P <0.01). At the 4-month examination, no significant differences were detected in PD reduction (1.1 versus 1.0 mm) or CAL gain (0.6 versus 0.4 mm). Both treatments resulted in reduction of the subgingival microflora. No significant differences in microbiologic composition were identified between the treatment groups at various time intervals. Degree of treatment discomfort scored significantly lower for the test than the control treatment modality.

CONCLUSION

The results of the trial failed to demonstrate any apparent advantage of using an Er:YAG laser for subgingival debridement, except less treatment discomfort perceived by the patients.

Accelerated reduction of post-skin-resurfacing erythema and discomfort with a combination of non-thermal blue and near infrared light

The prolonged crusting and erythematic phases following chemical and laser skin resurfacing create discomfort and aggravate patients. Depending on the aggressiveness of the procedure, post-procedure erythema may last from three weeks to several months. iClearXL (CureLight Ltd) is a non-contact, non-thermal blue (405-420 nm)/near infrared (850-900 nm) dual-band light source emitting up to 60 J/cm2 on a 30 cm by 30 cm treatment area. The blue component of the light source has been proven to have a significant anti-inflammatory effect, whereas the near infrared component enhances vascular circulation as well as lymphatic drainage in the thin, necrotized papillary layer. Facial skin laser resurfacing was performed on twelve patients. Starting one day after resurfacing, six patients received a daily 20-minute treatment of blue (405-420 nm)/near infrared (850-900 nm) light for six consecutive days, and six control patients were treated with the usual topical care protocol. Twelve days after the procedure, the treated group had a weighted average erythema score of 0.33 as compared to 1.33 in the control group. Two months after the procedure, the treated group had a weighted average erythema score of 0.16 as compared to 0.83 in the control group. Twelve days after the procedure, the treated group had a weighted average discomfort score of 0.33 as compared to 0.83 in the control group. The tested combination of non-thermal blue (405-420 nm)/near infrared (850-900 nm) dual-band light was found to significantly shorten the duration of post-laser-resurfacing erythema and discomfort with no side effects.

Expression of heat-shock protein 70 during limb development and regeneration in the axolotl

Urodele amphibians (e.g., axolotls) have the unique ability, among vertebrates, to regenerate perfectly many parts of their body after amputation. The limb has been the most widely studied regenerating structure in these organisms and provides an ideal model in which to understand how vertebrates can regenerate complex tissues. The present study focuses on Hsp-70, a member of the stress-related heat-shock protein family. This protein is normally induced after a stress or trauma such as heat-shock, ultraviolet irradiation, or wounding. Thus, studying its expression during axolotl limb regeneration, a response to an important traumatic event (amputation), is of great interest to further understand how the regenerative process is mediated. Using molecular biology and biochemical techniques, we have characterized both the spatiotemporal and quantitative expression patterns of Hsp-70 in axolotl development and regeneration. Our results show that Hsp-70 is expressed and regulated during axolotl development as in other vertebrates. Our data also demonstrate an up-regulation of the RNA transcript for Hsp-70 during limb regeneration as early as 24 hr after amputation that is maintained up to early differentiation. We also demonstrate a similar pattern of expression for the protein during regeneration. Finally, we show that axolotl Hsp-70 is induced threefold after heat-shock as observed in other vertebrates.

Experimental study on the healing process following laser welding of the cornea

An experimental study evaluating the application of laser welding of the cornea and the subsequent healing process is presented. The welding of corneal wounds is achieved after staining the cut walls with a solution of the chromophore indocyanine green, and irradiating them with a diode laser (810 nm) operating at low power (60 to 90 mW). The result is a localized heating of the cut, inducing controlled welding of the stromal collagen. In order to optimize this technique and to study the healing process, experimental tests, simulating cataract surgery and penetrating keratoplasty, were performed on rabbits: conventional and laser-induced suturing of corneal wounds were thus compared. A follow-up study 7 to 90 days after surgery was carried out by means of objective and histological examinations, in order to optimize the welding technique and to investigate the subsequent healing process. The analyses of the laser-welded corneas evidenced a faster and more effective restoration of the architecture of the stroma. No thermal damage of the welded stroma was detected, nor were there foreign body reactions or other inflammatory processes.

Combined 5-Fluorouracil and Er:YAG Laser Treatment in a Case of Recurrent Giant Keratoacanthoma of the Lower Leg

BACKGROUND

Keratoacanthomas are fast-growing squamous tumors, which usually show spontaneous regression. The development of giant variants with an aggressive behavior has been described. Although surgical excision remains the treatment of choice for very large keratoacanthomas, other therapeutic options including laser surgery and topical chemotherapy may be superior in special situations.

OBJECTIVE

The objective was to evaluate the efficacy of Er:YAG laser surgery combined with topical 5-fluorouracil treatment in a case of recurrent giant keratoacanthoma.

METHODS

A 64-year-old woman presented for evaluation and treatment of recurrent tumors in her face and extremities. Despite repeated invasive surgical removal of these lesions, recurrence of fast-growing giant keratoacanthomas developed in the pretibial region of her left lower leg. Owing to recurrence after conventional surgery and the tumor size, a novel treatment method using ablative Er:YAG laser combined with topical 5-fluorouracil was performed.

RESULTS

After four treatments with excellent patient compliance, histologic analysis of punch biopsies revealed tumor-free ulcerations. Complete epithelization was obtained after 9 weeks. Six months after the treatment, no recurrence was observed.

CONCLUSION

The combined use of ablative Er:YAG laser and topical 5-fluorouracil chemotherapy may be considered as an effective treatment option in cases of giant keratoacanthoma when conventional surgery is not indicated.

Closure of skin incisions in rabbits by laser soldering: I: Wound healing pattern

BACKGROUND AND OBJECTIVES

Temperature-controlled tissue laser soldering is an innovative sutureless technique awaiting only solid experimental data to become the gold-standard surgical procedure for incision closure. The goals of the current study were: (1) to define the optimal laser soldering conditions, (2) to explore the immediate skin reparative healing events after sealing the wound, and (3) to determine the long-term trajectory of skin wound healing.

STUDY DESIGN/MATERIALS AND METHODS

Skin incisions were generated over rabbit dorsa and were closed using different wound-closure interventions, in three groups: (a) closure, using a temperature-controlled infrared fiberoptic CO2 laser system, employing 47% bovine serum albumin as a solder; (b) wound closure by cyanoacrylate glues; and (c) wound closure by sutures. The reparative outcomes were evaluated macroscopically and microscopically, employing semi-quantitative grading indices.

RESULTS

Laser soldering of incisions at T = 65 degrees C emerged as the optimal method achieving immediate wound sealing. This in turn induced accelerated reparative events characterized by a reduced inflammatory reaction, followed by minimal scarring and leading to a fine quality healing.

CONCLUSIONS

Temperature-controlled laser soldering offers an accelerated wound reparative process with numerous advantages over the conventional methods. Further investigations may reveal additional benefits in the spectrum of advantages that this innovative surgical technology has to offer. This can introduce new scientific insight that will pave the way for clinical use.

Laser cartilage reshaping in an in vivo rabbit model using a 1.54 ?m Er:Glass laser

BACKGROUND AND OBJECTIVES

The potential applications for facial laser cartilage reshaping (LCR) have generated increasing clinical interest. This study aimed to evaluate in vivo LCR of the rabbit ear using a 1.54 micro m Er:Glass laser in combination with contact cooling.

STUDY DESIGN/MATERIALS AND METHODS

LCR was performed in vivo on 12 rabbit ears using a 1.54 micro m Er:Glass laser (Aramis, Quantel Medical, Clermont Ferrand, France) connected to a 4 mm chilled (+5 degrees C) handpiece placed in contact to the skin. Ear curvature was predetermined using a perforated cylindrical guide also used to standardize laser beam delivery. The treatment consisted of 15 spots (3 millisecond, 7 pulses, 12 J/cm(2), 2 Hz, 84/cm(2) cumulative fluence) applied on 10 contiguous parallel rows along the ear. After irradiation, the aluminum jig was replaced by a holder (10 mm diameter plastic tube) maintaining the curvature. This holder was secured with sutures and covered by an adhesive gauze bandage dressing to keep new form during 7 days. In order to assess thermal damage, biopsies were taken on irradiated areas and 1 week, 3 weeks and 6 weeks and studied using haematoxylin-erythrosin-safran (HES) and orcein staining and PCNA to detect cells in cycle.

RESULTS

Using the laser with the parameters given above, no immediate visible effects were observed on the skin (no swelling, no bleaching). There were also no late visible side effects like crusting, or blistering. The laser treatment produced changes in the shape of every ear after the dressing was removed. A slight tendency to recover its initial shape was observed for each ear. However, the curvature was stabilized after 10 days and the average shape retention was 64+/-4% at 6 weeks, with a curvature radius of 7.25+/-0.75 mm, instead of 5 mm initially. Histological examination of the laser irradiated side at 1 week showed an intact epidermis. A reduced inflammation process was seen in the dermis. A modification of half of the layer of cartilage was observed at the opposite side where the laser irradiation was applied and proliferative cells were detected inside. At 3 weeks, an important chondroblastic proliferation was observed around the area of contracted cartilage. At 6 weeks, significant thickening of the cartilage layer was observed (from 300 to 490 micro m) and new chondrocytes were clearly seen.

CONCLUSIONS

Rabbit ear cartilage can be reshaped with an Er:Glass laser. This technique could offer exciting possibilities that may help patients whose cartilage-lined joints have been affected by disease or trauma. This technique could be certainly utilized to correct alar cartilage deformities and septum deviation of cleft lips.