Myofibroblasts in healing laser excision wounds.

BACKGROUND AND OBJECTIVE: The lack of myofibroblasts, cells responsible for wound contraction, has been suggested to be the underlying factor to the clinically observed minimal contraction in CO2 laser wounds. However, the histologic background to this phenomenon in laser excisions has not been thoroughly clarified. Therefore, we analyzed the expression of myofibroblasts in healing laser excisions and control excisions made by scalpel. STUDY DESIGN/MATERIALS AND METHODS: CO2 laser (continuous wave, 5 W) or scalpel excision wounds were created in the dorsal tongue mucosa of 144 rats. Sixteen additional rats were kept as untreated controls. Specimens from the tongues were cut at 16 different healing time points and fixed in 10% formalin. Immunohistochemical stainings with monoclonal antibodies to vimentin and to alpha-smooth muscle actin were done to determine microscopically the contractile type of myofibroblasts. RESULTS: The maximum amount of myofibroblasts was almost three times higher in scalpel than in laser excisions. The peak value was reached at 4 days in laser and at 3 days in scalpel wounds. The increase reverted to normal levels at 14 days in laser and at 6 days in scalpel wounds, respectively. CONCLUSION: Myofibroblasts appeared and disappeared slower in laser wounds. There were clearly fewer myofibroblasts in CO2 laser than in corresponding scalpel excisions known to heal by contraction. The lack of contractile myofibroblasts, therefore, is suggested as the reason for the minimal degree of contraction in CO2 laser excision wounds.     

Eosinophils and mastocytes in healing laser excision wounds

Eosinophils can influence fibroblasts and the extracellular matrix in vitro and can participate in tissue remodelling in vivo. Therefore; we analysed the expression of eosinophils and mastocytes in healing laser excisions and control excisions made by scalpel. Carbon dioxide (CO₂) laser (continuous wave, 5 W) or scalpel excision wounds were created in the dorsal tongue mucosa of 96 rats. Sixteen additional rats were kept as untreated controls. Specimens from the tongues were cut at 16 different healing time points and fixed in 10% formalin. Histological staining with slow Giemsa was done to determine microscopically the eosinophils and mastocytes. Mastocytes were always present, especially in large numbers around blood vessels, in scalpel and in laser wounds. The maximum number of eosinophils was almost two times higher in scalpel excisions than in laser excisions. The peak value was reached after 6 days in laser wounds and after 3 days in scalpel wounds. The increase reverted to normal levels after 10 days in laser wounds and after 6 days in scalpel wounds. The appearance and disappearance of eosinophils was slower in laser wounds. Mastocytes were always present in both groups. This identification as a potential source of transforming growth factor (TGF) α and TGF β clearly permits a role for the eosinophils and influences epithelial cell proliferation, angiogenesis and organization of the wound.     

Use of low-intensity laser irradiation in the treatment of suppurative wounds

The article presents results of treatment of 372 patients with purulent wounds. In 187 patients a helium-cadmium laser was used (main group); in 185 patients (control group) other methods were used. The comparison of terms of cleansing the wounds from pyo-necrotic masses, appearance of granulations, epithelization++ and terms of wound healing and periods of staying at the hospital has shown high efficiency of the helium-cadmium laser for the treatment of purulent wounds. The average period at the hospital was 13.1 days, 66.8% of the patients were discharged after the complete healing of the wounds.     

Enhanced healing of full-thickness burn wounds using di-rhamnolipid

The aim of this study was to investigate the properties of di-rhamnolipid [alpha-L-rhamnopyranosyl-(1-2)-alpha-L-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoic acid, also referred to as di-rhamnolipid BAC-3] relating to the process of cutaneous wound healing. Di-rhamnolipid was prepared in a eucerin ointment and applied topically on full-thickness burn wounds in normal Sprague-Dawley rats covering 5% of the total body surface area. The rate of wound closure was measured over the period of 45 days. The collagen content was evaluated microscopically, by performing densitometric analysis on Verhoeff's stained histopathological slides of wound biopsies taken at the end of 45th day of di-rhamnolipid treatment. Di-rhamnolipid toxicity was assessed with the subcutaneous multi-dose study in Swiss-Webster mice. The treatment of full-thickness-burn wounds with topical 0.1% di-rhamnolipid accelerated the closure of wounds on day 21 of the treatment by 32% compared to the control (p < 0.05). On day 35, the wounds closed in all animals-treated with 0.1% di-rhamnolipid ointment while some rats in the control group had open wounds on days 35 and even 45. Histologic comparisons have shown that di-rhamnolipid significantly decreased collagen content in burn wounds (47.5%, p < 0.05) as compared to the vehicle-treated (control) wounds. Di-rhamnolipid was well-tolerated. The results of this study raise the possibility of potential efficacy of di-rhamnolipid in accelerating normal wound healing and perhaps in overcoming defects associated with healing failure in chronic wounds.     

Monitoring the healing of combat wounds using Raman spectroscopic mapping

Soldiers wounded in modern warfare present with extensive and complicated acute wounds, confounded by an overwhelming inflammatory response. The pathophysiology of acute wounds is unknown and timing of wound closure remains subjective. Collagen gene expression profiles are presented for 24 patients. Impaired healing wounds showed a twofold decrease in the up‐regulation of COL1A1 and COL3A1 genes in the beginning of the wound healing process, compared with normal healing wounds. By the final debridement, however, collagen gene expression profiles for normal and impaired healing wounds were similar for COL1A1 and COL3A1. In addition, Raman spectroscopic maps were collected of biopsy tissue sections, from the first and last debridements of 10 wounds collected from nine patients. Tissue components obtained for the debridement biopsies were compared to elucidate whether or not a wound healed normally. Raman spectroscopy showed a loss of collagen in five patients, indicated by a negative percent difference in the 1,665/1,445 cm^?1 band area ratios. Four healed patients showed an increased or unchanged collagen content. Here, we demonstrate the potential of Raman spectroscopic analysis of wound biopsies for classification of wounds as normal or impaired healing. Raman spectroscopy has the potential to noninvasively monitor collagen deposition in the wound bed, during surgical wound debridements, to help determine the optimal time for wound closure.     

Phase treatment of suppurative wounds using ultrasonics and laser irradiation in patients with diabetes mellitus]

A result of treatment of 112 patients with diabetes mellitus and purulent surgical diseases has been analysed. In the complex of treatment, a low-frequency ultrasound and laser radiation were employed. An advantage of the use of ultrasound at the first, and laser--at the second phase of a wound process was noted. Phasic use of ultrasound and laser accelerates the course of a wound process, contributes to shortening the duration of treatment.     

Anti-inflammatory effect of low-intensity laser on the healing of third-degree burn wounds in rats

Third-degree burn wounds are considered severe injuries because they destroy all the skin layers and may affect subcutaneous tissues, fasciae, muscles, and bones. To favor the healing process of the injured tissues, it is very useful to diminish the occurrence of the inflammatory process. The present study was aimed at comparing the effect of different energetic densities of AlGaInP laser on the inflammatory process and in the healing of third-degree burn wounds in Wistar rats. This study was approved by the Ethics Committee, in which 36 adult male rats were selected and suffered the induction of third-degree burn injury. These rats were divided as follows: group 1—control (treated with silver sulfadiazine), group 2—received energy density of 3 J/cm², and group 3—received energy density of 6 J/cm². All animals daily received an occlusive bandage with silver sulfadiazine and 8 % papain. The laser therapy was performed alternatively three times a week. The animals were evaluated on the 3rd, 7th, 14th, and 21st days after the initial lesion and euthanized for the macroscopic, histologic, and morphometric analysis. A higher production of collagen was observed at 7 days and a greater re-epithelialization at 21 days in group 3 (6 J/cm²). Furthermore, the latter when compared to the other groups presented macroscopically a better aspect of the scar at 21 days with more granulation tissue and fibrosis. We conclude that the AlGaInP laser used in dosages of 3 and 6 J/cm² favors the healing of third-degree burn wounds induced in rats.     

Photobiomodulation of wound healing via visible and infrared laser irradiation

Fibroblast cells are known to be one of the key elements in wound healing process, which has been under the scope of research for decades. However, the exact mechanism of photobiomodulation on wound healing is not fully understood yet. Photobiomodulation of 635 and 809 nm laser irradiation at two different energy densities were investigated with two independent experiments; first, in vitro cell proliferation and then in vivo wound healing. L929 mouse fibroblast cell suspensions were exposed with 635 and 809 nm laser irradiations of 1 and 3 J/cm² energy densities at 50 mW output power separately for the investigation of photobiomodulation in vitro. Viabilities of cells were examined by means of MTT assays performed at the 24th, 48th, and 72nd hours following the laser irradiations. Following the in vitro experiments, 1 cm long cutaneous incisional skin wounds on Wistar albino rats (n = 24) were exposed with the same laser sources and doses in vivo. Wound samples were examined on 3rd, 5th, and 7th days of healing by means of mechanical tensile strength tests and histological examinations. MTT assay results showed that 635 nm laser irradiation of both energy densities after 24 h were found to be proliferative. One joule per square centimeter laser irradiation results also had positive effect on cell proliferation after 72 h. However, 809 nm laser irradiation at both energy densities had neither positive nor negative affects on cell viability. In vivo experiment results showed that, 635 nm laser irradiation of both energy densities stimulated wound healing in terms of tensile strength, whereas 809 nm laser stimulation did not cause any stimulative effect. The results of mechanical tests were compatible with the histological evaluations. In this study, it is observed that 635 nm laser irradiations of low energy densities had stimulative effects in terms of cell proliferation in vitro and mechanical strength of incisions in vivo. However, 809 nm laser irradiations at the same doses did not have any positive effect.     

Low-energy helium-neon laser irradiation and the tensile strength of incisional wounds in the rat

Low-level laser energy has been reported to modulate the wound healing process in some but not all studies. To examine this hypothesis, we investigated incisional wounds made on the dorsal pelt of rats for changes in the healing produced by low-level irradiation with a helium-neon laser. The incisions were made with a scalpel and closed with sutures. The rats were irradiated daily for 12 days with four levels of laser light (0.0, 0.47, 0.93, and 1.73 J/cm(2)). Analysis of wound tensile strength indicated a possible strengthening of fresh wounds at the highest levels of irradiation (1.73 J/cm(2)). No change was observed in the tensile strength of formalin-fixed wounds. The distribution of measured tensile strengths did not follow normal statistics; instead they showed a platykurtic distribution. Using resampling statistics, where no assumption is made as to the nature of the distribution, we found that the results were contrary to other studies: no biostimulatory effect was seen.     

Low level laser therapy for healing acute and chronic wounds - the extendicare experience

The purpose of the study is to assess the effectiveness of low level laser therapy for wound healing when combined with the Extendicare Wound Prevention and Management Program. Sixteen residents at a Canadian Extendicare nursing home had a total of 27 sites treated consisting of 23 open wounds and 4 'at risk' areas. Of the 23 open wounds, two wounds in between toes were not able to be 'traced' and deemed 'immeasurable' wounds, resulting in 21 open, measured wounds. The four 'at risk' (closed) areas were treated preventatively. Pressure, venous insufficiency and diabetic wounds were included. The majority (12/21) or 57.1%, of the wounds were chronic (>or=3 months duration) and 42.9% were acute (<3 months duration). The primary outcome measures included the PUSH Tool score, EZ Graph tracings and photographs. Secondary outcome measures were employed to better understand potential barriers to successful integration into clinical practice. Feedback on the effectiveness of low level laser therapy, the education program and determinations of hands-on relevance was sought from staff. At the end of the 9-week trial, the majority (61.9%) of the 21 wounds achieved significant improvement (>or=50% wound closure). Nine (42.8%) had 100% closure. Some improvement was seen in 14.3% and 23.8% of wounds demonstrated no change. Chronic and acute wounds had similar improvement. None of the wounds in this debilitated, frail population deteriorated during the study and no negative consequences of treatment were encountered. Without staff support, even if new technology has positive clinical outcomes, success would be limited. Staff rated low level laser, easy to learn and use, effective for the majority of their residents worth the additional time. Staff requested a continuation of low level laser even after study completion.