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Any cutaneous damage triggers a cascade of biological effects in the skin responsible for re-establishing skin integrity. Wound healing is a complex biological process inducing dermal remodelling leading at least to a visible scar, and sometimes to hypertrophic or keloid scars. Recent studies suggest that using a laser generates a precisely defined thermal effect in the skin, improving the wound healing process and potentially opening the door to scarless healing.

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.

Lasers are now widely used for treating numerous cutaneous lesions, for scar revision (hypertrophic and keloid scars), for tissue welding, and for skin resurfacing and remodeling (wrinkle removal). In these procedures lasers are used to generate heat. The modulation of the effect (volatilization, coagulation, hyperthermia) of the laser is obtained by using different wavelengths and laser parameters. The heat source obtained by conversion of light into heat can be very superficial, yet intense, if the laser light is well absorbed (far-infrared:CO(2) or Erbium:Yttrium Aluminum Garnet [Er:YAG] lasers), or it can be much deeper and less intense if the laser light is less absorbed by the skin (visible or near-infrared). Lasers transfer energy, in the form of heat, to surrounding tissues and, regardless of the laser used, a 45-50 degrees C temperature gradient will be obtained in the surrounding skin. If a wound healing process exists, it is a result of live cells reacting to this low temperature increase. The generated supraphysiologic level of heat is able to induce a heat shock response (HSR), which can be defined as the temporary changes in cellular metabolism. These changes are rapid and transient, and are characterized by the production of a small family of proteins termed the heat shock proteins (HSP). Recent experimental studies have clearly demonstrated that HSP 70, which is over-expressed following laser irradiation, could play a role with a coordinated expression of other growth factors such as transforming growth factor (TGF)-beta. TGF-beta is known to be a key element in the inflammatory response and the fibrogenic process. In this process, the fibroblasts are the key cells since they produce collagen and extracellular matrix. In conclusion, the analysis of the literature, and the fundamental considerations concerning the healing process when using thermal lasers, are in favor of a modification of the growth factors synthesis after laser irradiation, induced by an HSR. An extensive review of the different techniques and several clinical studies confirm that thermal lasers could effectively promote skin wound healing, if they are used in a controlled manner.

Background and objective Selective dermal remodeling consists of inducing collagen tightening, neocollagen synthesis, or both, without damage to the overlying epidermis. This experimental study aimed to evaluate an Er:Glass laser emitting at 1.54 micrometer combined with contact cooling to target the upper dermis while protecting the epidermis. Study design/materials and methods Male hairless rats were used for the study. Different fluences (26-30 J/cm(2)) by using single 3-ms pulse irradiation or pulse train irradiation (1.1 J, 3 Hz) and different cooling temperatures (+5 degrees C, 0 degrees C, -5 degrees C) were screened with clinical examination and histologic evaluation at 1, 3, and 7 days after laser irradiation. Results The clinical effects were clearly dose and temperature cooling dependent. It seemed that single pulse irradiation led to epidermal whitening in most cases, whatever the cooling temperature. Conversely, pulse train irradiation showed reproducible epidermal preservation and confinement of the thermal damage into the dermis. New collagen synthesis was confirmed by a marked fibroblastic proliferation, detected in the lower dermis at day 3 and clearly seen in the upper dermis at day 7. Conclusion This new laser seems to be a promising new tool for the treatment of skin laxity, solar elastosis, facial rhytides, and mild reduction of wrinkles.

Normal wound healing of the skin results in a flat and flexible scar. The ideal end point would be total regeneration, with the new tissue having the same structural, aesthetic, and functional attributes as the original uninjured skin. Scars are often considered trivial, but they can be disfiguring and aesthetically unpleasant and cause severe itching, tenderness, pain, sleep disturbance, anxiety, and depression [1]. Cosmetic results obtained after skin surgery are a key component of patient satisfaction. Surgical skin scars are a type of scar that can benefit from laser therapy. Redness and telangiectasia developing in such scars usually spontaneously remit, but often slowly and incompletely. Laser can not only accelerate this decolorizing process, it can also advance the end point closer to the complete absence of redness with improvement in scar texture and pliability with minimal side effects [2]. Recently, Capon et al. [3] showed the ability of a 815-nm diode-laser system to assist wound closure leading to an acceleration and an improvement of wound healing with indiscernible resulting scar in hairless rats. The purpose of this study was to improve the appearance of scars, by improving through a thermal action the wound healing process. This thermal action was generated by an 810-nm laser source. This specific wavelength choice ensured a minimal epidermal damage as neither blood nor water can absorb at this wavelength. This pilot study aimed at evaluating the 810-nm diode-laser system to accelerate and improve the healing process in surgical scars, immediately after skin closure, of patients with Fitzpatrick skin type I–IV. Five patients (five females) with Fitzpatrick skin types I–IV and fresh surgical scars of greater than 2 cm (i.e., horizontal scars from abdominoplasty) were enrolled in this prospective pilot study (Table 1). This clinical trial has been approved by the Ethics Committee (Comite Consultatif de Protection des Personnes en Recherche Biomedicale (CCPPRB) de la region Nord Pas-de-Calais). Patients under 18 years of age, with dark skin (phototypes V or VI), pregnant women, and patients with a history of malignant tumor skin disease, bacterial or viral infectious skin disease, immunosuppression and treated by a longterm corticosteroids treatment were excluded. Patients were treated with fluence comprised between 80 and 120 J/ cm, in order to evaluate safety and performance of the 810-nm diode-laser system. Each surgical incision was divided into two fields, with 8 cm receiving an 810-nm diode-laser treatment (4 mm diameter beam, continuous wave, total exposure duration: 3–4 seconds). The other part was not treated. Treated and untreated portions were selected randomly. Scars were evaluated for pigmentation, vascularity, pliability, and height by surgeon and patient at 10 days, 3 months, and 12 months. A comparative scar evaluation based on cosmetic appearance using a visual analog scale from 5 (worst) to 5 (best) was performed by surgeon and patients. Overall appearance ratings ranging from an optimum of 1 to a minimum of 4 (11⁄4 excellent, 21⁄4 good

The use of lasers has been proposed for scar revision. A recent pilot clinical study demonstrated that lasers could also be used immediately after surgery to reduce the appearance of scars. The LASH (Laser-Assisted Skin Healing) technique induces a temperature elevation in the skin which modifies the wound-healing process. We report a prospective comparative clinical trial aimed at evaluating an 810-nm diode-laser system to accelerate and improve the healing process in surgical scars immediately after skin closure.Twenty-nine women and 1 man (mean age = 41.4 years; Fitzpatrick skin types I-IV) were included to evaluate the safety and performance of the laser system. The laser dose (or fluence in J/cm(2)) was selected as a function of phototype and skin thickness. Each surgical incision (e.g., abdominoplasty) was divided into two parts. An 8-cm segment was treated with the laser immediately after skin closure. A separate 8-cm segment was left untreated as a control. Clinical evaluations (overall appearance ratings, comparative scar scale) of all scars were conducted at 10 days, 3 months, and 12 months by both surgeon and patients. Profilometry analysis from silicone replicas of the skin was done at 12 months. Wilcoxon signed-rank test analyses were performed.Twenty-two patients were treated using a high dose (80-130 J/cm(2)) and 8 patients with a low dose (80 J/cm(2)). At 12 months in the high-dose group, both surgeon and patients reported an improvement rate of the laser-treated segment over the control area of 72.73 and 59.10%, respectively. For these patients, profilometry results showed a decrease in scar height of 38.1% (p = 0.027) at 12 months for the laser-treated segment versus control. Three patients treated with higher doses (115 J/cm(2)) experienced superficial burns on the laser-treated segment, which resolved in about 5-7 days. For the eight patients treated at low dosage (80 J/cm(2)), there was no significant difference in the treated segment versus the control segment. No side effects were observed.This prospective comparative trial demonstrates that an 810-nm diode laser treatment, performed immediately after surgery, can improve the appearance of a surgical scar. The dose plays a great role in scar improvement and must be well controlled. There is interest in LASH for hypertrophic scar revision. LASH can be used to prevent and reduce scars in plastic surgery.

Laser assisted skin closure (LASC) has been shown to accelerate wound healing and to reduce scarring. However, the mechanisms involved during the cutaneous wound repair after LASC remain unclear. This study aimed to evaluate the inflammation process and the wound repair fibroplasia, particularly the involvement of granulation tissue fibroblasts (myofibroblasts).

The authors report an original 1.9-micrometers diode laser assisted microvascular anastomosis (LAMA) in human. This technique has been applied in 20 patients during reconstructive surgery for digital replantations (nequals6), for digital revascularizations (nequals4) and for free flap transfers (nequals10). LAMA were always performed on vessel (16 arteries and 6 veins) which did not impede the chance of success of the surgical procedure in case of thrombosis. LAMA was performed with a 1.9-micrometers diode laser after placement of 2 equidistant stitches at 180 degrees. The diode spot was obtained by means of a 300-micrometers optic fiber transmitted to the vessel wall via a pencil size hand piece. The following parameters were used: spot size equals 500 micrometers , power equals 70 to 220 mW, pulse duration equals 0.7 to 3 seconds. Ten to 15 spots were applied on each face. The mechanism involved is a thermal effect on the collagen of the adventitia and media leading to a phenomenon which the authors have termed 'heliofusion'. Immediate assessment consisted in evaluating the permeability by patency test (O'Brien) and water tightness. Secondary assessment consisted in evaluating the clinical success, confirmed by Doppler at one month.

Background We previously reported that skin closure is improved by photoirradiation of the wound margins with an 815-nm diode laser system. Objectives To determine whether the beneficial effects of laser treatment involve the overexpression of the inducible 72-kDa heat shock protein, Hsp70. Methods Expression of Hsp70 was investigated by immunocytochemistry in normal hairless rat dorsal skin and compared with its expression after laser photoirradiation. Results Constitutive expression of Hsp70 was mainly confined to the upper epidermal layer. Laser irradiation further increased epidermal expression of Hsp70 while inducing de novo synthesis of the protein in dermal structures, particularly around blood vessels, hair follicles and sebaceous glands. Laser-induced expression of Hsp70 was still present 7 days after photoirradiation. Conclusions Laser-induced expression of Hsp70 might contribute to improved tissue regeneration and 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/cm2. 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

Selective dermal remodeling using diode or 1.32 micrometer Nd:YAG lasers has been recently proposed for skin rejuvenation. This new technique consists in inducing collagen tightening and/or neocollagen synthesis without significant damage of the overlying epidermis. Such an approach requires (1) a cooling system in order to target dermal collagen with relatively good protection of the epidermal layer, (2) a specific wavelength for confining the thermal damage into the upper dermis (100 to 400 micrometer). Based on previous studies, demonstrating a better water absorption and a reduced melanin absorption at 1.54 micrometer compared to the 1.32 micrometer, this experimental study aimed to evaluate a new laser (co-doped Yb-Er:phosphate glass material, Aramis, Quantel-France) emitting at 1.54 micrometer. This laser was used in combination with the Dermacool system (Dermacool, Mableton, USA) in order to achieve epidermis cooling before, during and after irradiation. Male hairless rats were used for the study. Pulse train irradiation (1.1 J, 3 Hz, 30 pulses) and different cooling temperatures (+5 degree(s)C, 0 degree(s)C, -5 degree(s)C) were screened with clinical examination and histological evaluation at 1, 3, and 7 days after laser irradiation. The clinical effects showed that pulse train irradiation produced reproducible epidermal preservation and confinement of the thermal damage into the dermis. The different cooling temperatures did not provide detectable differences in terms of size and depth of thermal damage. New collagen synthesis was confirmed by a marked fibroblastic proliferation, detected in the lower dermis at D3 and clearly seen in the upper dermis at D7. This new laser appears to be a promising new tool for the treatment of skin laxity, solar elastosis, facial rhytids and mild reduction of wrinkles.

This study aimed to evaluate a 815 nm diode-laser system to assist wound closure. It was proposed to determine an optimal fluence being able to accelerate and improve heating process without thermal damage after laser irradiation. Male hairless rats with dorsal skin incisions were used for the study. Different fluences were screened (76 to 346 J/cm2) in a first phase with clinical examination at 3, 7, 15 and 21 days after surgery. Best results were obtained for a fluence of 145 J/cm2 and 3 sec time of exposure. A second phase was conducted to valid these parameters with histological study and determination of tensile strength at 3, 7, 15 and 21 days after surgery. LASC was 4 times faster to process than conventional suture. In the laser group with an optimal fluence of 145 J/cm2, healing was accelerated. The resulting scar was more indiscernible than in the control groups. Histological aspect was better with continuous epidermis and dermis at 3 days in most cases. Tensile strength was 30 to 58% greater than in control groups (1141 g/cm2 at 7 days in the laser group versus 856 g/cm2 and 724 g/cm2 in the control groups, p < 0.001).© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.