Utility of a human–mouse xenograft model and in vivo near‐infrared fluorescent imaging for studying wound healing

To study the complex cellular interactions involved in wound healing, it is essential to have an animal model that adequately mimics the human wound microenvironment. Currently available murine models are limited because wound contraction introduces bias into wound surface area measurements. The purpose of this study was to demonstrate utility of a human–mouse xenograft model for studying human wound healing. Normal human skin was harvested from elective abdominoplasty surgery, xenografted onto athymic nude (nu/nu) mice, and allowed to engraft for 3 months. The graft was then wounded using a 2‐mm punch biopsy. Wounds were harvested on sequential days to allow tissue‐based markers of wound healing to be followed sequentially. On the day of wound harvest, mice were injected with XenoLight RediJect cyclooxygenase‐2 (COX‐2) probe and imaged according to package instructions. Immunohistochemistry confirms that this human–mouse xenograft model is effective for studying human wound healing in vivo. Additionally, in vivo fluorescent imaging for inducible COX‐2 demonstrated upregulation from baseline to day 4 (P = 0·03) with return to baseline levels by day 10, paralleling the reepithelialisation of the wound. This human–mouse xenograft model, combined with in vivo fluorescent imaging provides a useful mechanism for studying molecular pathways of human wound healing.     

Light‐emitting diodes in dermatology: A systematic review of randomized controlled trials

Objective

In dermatology, patient and physician adoption of light‐emitting diode (LED) medical technology continues to grow as research indicates that LEDs may be used to treat skin conditions. The goal of this systematic review is to critically analyze published randomized controlled trials (RCTs) and provide evidence‐based recommendations on the therapeutic uses of LEDs in dermatology based on published efficacy and safety data.

Methods

A systematic review of the published literature on the use of LED treatments for skin conditions was performed on September 13th 2017.

Results

Thirty‐one original RCTs were suitable for review.

Conclusions

LEDs represent an emerging modality to alter skin biology and change the paradigm of managing skin conditions. Acne vulgaris, herpes simplex and zoster, and acute wound healing received grade of recommendation B. Other skin conditions received grade of recommendation C or D. Limitations of some studies include small patient sample sizes (n < 20), absent blinding, no sham placebo, and varied treatment parameters. Due to few incidences of adverse events, affordability, and encouraging clinical results, we recommend that physicians use LEDs in clinical practice and researchers continue to explore the use of LEDs to treat skin conditions. Lasers Surg. Med. 50:613–628, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.     

UV fluorescence excitation imaging of healing of wounds in skin: Evaluation of wound closure in organ culture model

Background and Objective

Molecules native to tissue that fluoresce upon light excitation can serve as reporters of cellular activity and protein structure. In skin, the fluorescence ascribed to tryptophan is a marker of cellular proliferation, whereas the fluorescence ascribed to cross‐links of collagen is a structural marker. In this work, we introduce and demonstrate a simple but robust optical method to image the functional process of epithelialization and the exposed dermal collagen in wound healing of human skin in an organ culture model.

Materials and Methods

Non‐closing non‐grafted, partial closing non‐grafted, and grafted wounds were created in ex vivo human skin and kept in culture. A wide‐field UV fluorescence excitation imaging system was used to visualize epithelialization of the exposed dermis and quantitate wound area, closure, and gap. Histology (H&E staining) was also used to evaluate epithelialization.

Results

The endogenous fluorescence excitation of cross‐links of collagen at 335 nm clearly shows the dermis missing epithelium, while the endogenous fluorescence excitation of tryptophan at 295 nm shows keratinocytes in higher proliferating state. The size of the non‐closing wound was 11.4 ± 1.8 mm and remained constant during the observation period, while the partial‐close wound reached 65.5 ± 4.9% closure by day 16. Evaluations of wound gaps using fluorescence excitation images and histology images are in agreement.

Conclusions

We have established a fluorescence imaging method for studying epithelialization processes, evaluating keratinocyte proliferation, and quantitating closure during wound healing of skin in an organ culture model: the dermal fluorescence of pepsin‐digestible collagen cross‐links can be used to quantitate wound size, closure extents, and gaps; and, the epidermal fluorescence ascribed to tryptophan can be used to monitor and quantitate functional states of epithelialization. UV fluorescence excitation imaging has the potential to become a valuable tool for research, diagnostic and educational purposes on evaluating the healing of wounds. Lasers Surg. Med. 48:678–685, 2016. © 2016 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.     

Comparative study of wound healing in rat skin following incision with a novel picosecond infrared laser (PIRL) and different surgical modalities

Background and Objective

As a result of wound healing the original tissue is replaced by dysfunctional scar tissue. Reduced tissue damage during surgical procedures beneficially affects the size of the resulting scar and overall healing time. Thus the choice of a particular surgical instrument can have a significant influence on the postoperative wound healing. To overcome these problems of wound healing we applied a novel picosecond infrared laser (PIRL) system to surgical incisions. Previous studies indicated that negligible thermal, acoustic, or ionization stress effects to the surrounding tissue results in a superior wound healing.

Study Design/Materials and Methods

Using the PIRL system as a surgical scalpel, we performed a prospective wound healing study on rat skin and assessed its final impact on scar formation compared to the electrosurgical device and cold steel. As for the incisions, 6 full‐thickness, 1‐cm long‐linear skin wounds were created on the dorsum of four rats using the PIRL, an electrosurgical device, and a conventional surgical scalpel, respectively. Rats were euthanized after 21 days of wound healing. The thickness of the subepithelial fibrosis, the depth and the transverse section of the total scar area of each wound were analyzed histologically.

Results

After 21 days of wound healing the incisions made by PIRL showed minor scar tissue formation as compared to the electrosurgical device and the scalpel. Highly significant differences (P < 0.001) were noted by comparing the electrosurgical device with PIRL and scalpel. The transverse section of the scar area also showed significant differences (P = 0.043) when comparing PIRL (mean: 141.46 mm²; 95%CI: 105.8–189.0 mm²) with scalpel incisions (mean: 206.82 mm²; 95%CI: 154.8–276.32 mm²). The subepithelial width of the scars that resulted from using the scalpel were 1.3 times larger than those obtained by using the PIRL (95%CI: 1.0–1.6) though the difference was not significant (P < 0.083).

Conclusions

The hypothesis that PIRL results in minimal scar formation with improved cosmetic outcomes was positively verified. In particular the resection of skin tumors or pathological scars, such as hypertrophic scars or keloids, are promising future fields of PIRL application. Lasers Surg. Med. 48:385–391, 2016. © 2016 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.     

Up‐regulation of fibroblast growth factor (FGF) 9 expression and FGF‐WNT/β‐catenin signaling in laser‐induced wound healing

Fibroblast growth factor (FGF) 9 is secreted by both mesothelial and epithelial cells, and plays important roles in organ development and wound healing via WNT/β‐catenin signaling. The aim of this study was to evaluate FGF9 expression and FGF‐WNT/β‐catenin signaling during wound healing of the skin. We investigated FGF9 expression and FGF‐WNT/β‐catenin signaling after laser ablation of mouse skin and adult human skin, as well as in cultured normal human epidermal keratinocytes (NHEKs) upon stimulation with recombinant human (rh) FGF9 and rh‐transforming growth factor (TGF)‐β1. Our results showed that laser ablation of both mouse skin and human skin leads to marked overexpression of FGF9 and FGF9 mRNA. Control NHEKs constitutively expressed FGF9, WNT7b, WNT2, and β‐catenin, but did not show Snail or FGF receptor (FGFR) 2 expression. We also found that FGFR2 was significantly induced in NHEKs by rhFGF9 stimulation, and observed that FGFR2 expression was slightly up‐regulated on particular days during the wound healing process after ablative laser therapy. Both WNT7b and WNT2 showed up‐regulated protein expression during the laser‐induced wound healing process in mouse skin; moreover, we discerned that the stimulatory effect of rhFGF9 and rhTGF‐β1 activates WNT/β‐catenin signaling via WNT7b in cultured NHEKs. Our data indicated that rhFGF9 and/or rhTGF‐β1 up‐regulate FGFR2, WNT7b, and β‐catenin, but not FGF9 and Snail; pretreatment with rh dickkopf‐1 significantly inhibited the up‐regulation of FGFR2, WNT7b, and β‐catenin. Our results suggested that FGF9 and FGF‐WNT/β‐catenin signaling may play important roles in ablative laser‐induced wound healing processes.     

Wound healing in a fetal,adult, and scar tissue model: A comparative study

Early gestation fetal wounds heal without scar formation. Understanding the mechanism of this scarless healing may lead to new therapeutic strategies for improving adult wound healing. The aims of this study were to develop a human fetal wound model in which fetal healing can be studied and to compare this model with a human adult and scar tissue model. A burn wound (10 × 2 mm) was made in human ex vivo fetal, adult, and scar tissue under controlled and standardized conditions. Subsequently, the skin samples were cultured for 7, 14, and 21 days. Cells in the skin samples maintained their viability during the 21‐day culture period. Already after 7 days, a significantly higher median percentage of wound closure was achieved in the fetal skin model vs. the adult and scar tissue model (74% vs. 28 and 29%, respectively, p<0.05). After 21 days of culture, only fetal wounds were completely reepithelialized. Fibroblasts migrated into the wounded dermis of all three wound models during culture, but more fibroblasts were present earlier in the wound area of the fetal skin model. The fast reepithelialization and prompt presence of many fibroblasts in the fetal model suggest that rapid healing might play a role in scarless healing.     

Negative‐pressure wound dressings to secure split‐thickness skin grafts in the perineum

Several researches have shown that negative‐pressure wound dressings can secure split‐thickness skin grafts and improve graft survival. However, in anatomically difficult body regions such as the perineum it is questionable whether these dressings have similar beneficial effects. In this study, we evaluated the effects of negative‐pressure wound dressings on split‐thickness skin grafts in the perineum by comparing wound healing rate and complication rate with that of tie‐over dressings. A retrospective chart review was performed for the patients who underwent a split‐thickness skin graft to reconstruct perineal skin defects between January 2007 and December 2011. After grafting, the surgeon selected patients to receive either a negative‐pressure dressing or a tie‐over dressing. In both groups, the initial dressing was left unchanged for 5 days, then changed to conventional wet gauze dressing. Graft success was assessed 2 weeks after surgery by a single clinician. A total of 26 patients were included in this study. The mean age was 56·6 years and the mean wound size was 273·1 cm². Among them 14 received negative‐pressure dressings and 12 received tie‐over dressings. Negative‐pressure dressing group had higher graft taken rate (P = 0·036) and took shorter time to complete healing (P = 0·01) than tie‐over dressing group. The patients with negative‐pressure dressings had a higher rate of graft success and shorter time to complete healing, which has statistical significance. Negative‐pressure wound dressing can be a good option for effective management of skin grafts in the perineum.     

Comparing the effects of nebivolol and dexpanthenol on wound healing: an experimental study

Wound healing is a dynamic, interactive process that is initiated in response to injury. A number of investigations and clinical studies have been performed to determine new approaches for the improvement of wound healing. The aim of this study was to compare the effects of dexpanthenol, a molecule that is widely used for improving wound healing, and nebivolol, a molecule that increases nitric oxide release, on wound healing. A total of 30 rats were divided into three equal groups (n = 10). A linear 2 cm incision was made in the rats' skin. No treatment was administered in the first (control) group. Dexpanthenol cream was administered to the rats in the second group and 5% nebivolol cream was administered to the rats in the third group. The wound areas of all of the rats were measured on certain days. On the 21^st day, all wounds were excised and histologically evaluated. The wound healing rates of the dexpanthenol and nebivolol groups were higher than those of the control group (P < 0·05). However, the wound healing rates of the dexpanthenol and nebivolol groups were not significantly different. Nebivolol and dexpanthenol have comparable effects on wound healing.     

Direct biological effects of fractional ultrapulsed CO<Subscript>2</Subscript> laser irradiation on keratinocytes and fibroblasts in human organotypic full-thickness 3D skin models

Molecular effects of various ablative and non-ablative laser treatments on human skin cells—especially primary effects on epidermal keratinocytes and dermal fibroblasts—are not yet fully understood. We present the first study addressing molecular effects of fractional non-sequential ultrapulsed CO₂ laser treatment using a 3D skin model that allows standardized investigations of time-dependent molecular changes ex vivo. While histological examination was performed to assess morphological changes, we utilized gene expression profiling using microarray and qRT-PCR analyses to identify molecular effects of laser treatment. Irradiated models exhibited dose-dependent morphological changes resulting in an almost complete recovery of the epidermis 5 days after irradiation. On day 5 after laser injury with a laser fluence of 100 mJ/cm², gene array analysis identified an upregulation of genes associated with tissue remodeling and wound healing (e.g., COL12A1 and FGF7), genes that are involved in the immune response (e.g., CXCL12 and CCL8) as well as members of the heat shock protein family (e.g., HSPB3). On the other hand, we detected a downregulation of matrix metalloproteinases (e.g., MMP3), differentiation markers (e.g., LOR and S100A7), and the pro-inflammatory cytokine IL1α.Overall, our findings substantiate the understanding of time-dependent molecular changes after CO₂ laser treatment. The utilized 3D skin model system proved to be a reliable, accurate, and reproducible tool to explore the effects of various laser settings both on skin morphology and gene expression during wound healing.     

A pre‐clinical functional assessment of an acellular scaffold intended for the treatment of hard‐to‐heal wounds

The majority of the population experience successful wound‐healing outcomes; however, 1–3% of those aged over 65 years experience delayed wound healing and wound perpetuation. These hard‐to‐heal wounds contain degraded and dysfunctional extracellular matrix (ECM); yet, the integrity of this structure is critical in the processes of normal wound healing. Here, we evaluated a novel synthetic matrix protein for its ability to act as an acellular scaffold that could replace dysfunctional ECM. In this regard, the synthetic protein was subjected to adsorption and diffusion assays using collagen and human dermal tissues; evaluated for its ability to influence keratinocyte and fibroblast attachment, migration and proliferation and assessed for its ability to influence in vivo wound healing in a porcine model. Critically, these experiments demonstrate that the matrix protein adsorbed to collagen and human dermal tissue but did not diffuse through human dermal tissue within a 24‐hour observation period, and facilitated cell attachment, migration and proliferation. In a porcine wound‐healing model, significantly smaller wound areas were observed in the test group compared with the control group following the third treatment. These data provide evidence that the synthetic matrix protein has the ability to function as an acellular scaffold for wound‐healing purposes.     

Rapid,high‐fluence multi‐pass q‐switched laser treatment of tattoos with a transparent perfluorodecalin‐infused patch: A pilot study

Background and Objectives

Perfluorodecalin (PFD) has previously been shown to rapidly dissipate the opaque, white micro‐bubble layer formed after exposure of tattoos to Q‐switched lasers [1]. The current pilot study was conducted to qualitatively determine if the use of a transparent PFD‐infused silicone patch would result in more rapid clearance of tattoos than conventional through‐air techniques.

Materials and Methods

Black or dark blue tattoos were divided into two halves in a single‐site IRB‐approved study with 17 subjects with Fitzpatrick skin types I–III. One half of each tattoo served as its own control and was treated with one pass of a standard Q‐switched Alexandrite laser (755 nm). The other half of the tattoo was treated directly through a transparent perfluorodecalin (PFD) infused patch (ON Light Sciences, Dublin, CA). The rapid whitening reduction effect of the Patch routinely allowed three to four laser passes in a total of approximately 5 minutes. Both sides were treated at highest tolerated fluence, but the optical clearing, index‐matching, and epidermal protection properties of the PFD Patch allowed significantly higher fluence compared to the control side. Standard photographs were taken at baseline, immediately prior to treatment with the PFD Patch in place, and finally before and after each treatment session. Treatments were administered at 4‐ to 6‐week intervals.

Results

In a majority of subjects (11 of 17), tattoos treated through a transparent PFD‐infused patch showed more rapid tattoo clearance with higher patient and clinician satisfaction than conventional treatment. In no case did the control side fade faster than the PFD Patch side. No unanticipated adverse events were observed.

Conclusions

Rapid multi‐pass treatment of tattoos with highest tolerated fluence facilitated by a transparent PFD‐infused patch clears tattoos more rapidly than conventional methods. Lasers Surg. Med. 47:613–618, 2015. © 2015 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals, Inc.     

New model of radiation-induced skin ulcer in rats

Abstract

Our aim was to provide a new animal model for intractable skin ulcers in irradiated rats. Twenty-four rats were irradiated with total single radiographic irradiation doses of 10, 15, 20, and 30 Gy. The skin was observed for 6 months. In the 10-Gy group, there were no visible changes to the skin. In the 15-Gy group, epilation and depigmentation were seen about 2 weeks after irradiation. In the groups over 20-Gy, minor erosion or skin ulcers appeared in most rats. The wounds healed in the 20-Gy group, but many in the 30-Gy group could not be healed. A further 36 rats were irradiated with 20 Gy, and this was followed by the creation of cutaneous full-thickness defects at different periods. The size of the wounds was measured on days 0, 3, 5, 7, 10, and 14. Delayed wound healing was found in the irradiated groups compared with the unirradiated group (p = 0.01). There were no differences in the time of ulceration, except in the Day 7 group (p = 0.03).     

Minimally Invasive Bipolar Fractional Radiofrequency Treatment Upregulates Anti‐Senescence Pathways

Background

The sirtuin gene family has been implicated in various anti‐senescence pathways. Its connection, if any, with the skin wound healing response has yet to be elucidated.

Objective

The goal of our study was to better understand the effects of FRF treatment on the sirtuin anti‐senescence pathway in skin.

Methods

Human abdominal skin was treated with FRF, and then harvested at 0, 2, 14, and 28 days post‐treatment to assess for temporal changes in gene expression levels.

Results

Decreased levels of SIRT1, 3, 5, and 7 were observed immediately post‐FRF treatment. By Day 2, SIRT1, 6, and 7 expressions increased 50–100%. SIRT6 and 7 expression continued to increase through Day 28. Expression levels of apoptosis genes FoxO3 and p53 decreased, while Bax levels increased by Day 28.

Conclusions

Our results raise the possibility that sirtuin activity may be used as an accurate corollary to clinical improvement in skin quality. Lasers Surg. Med. 9999:XX–XX, 2013. © 2013 Wiley Periodicals, Inc.     

Evaluation of Hyphecan (1‐4,2‐acetamide‐deoxy‐B‐D‐glucan polymer) on wound healing in a rodent model

Objective: To evaluate the effect of an artificial skin Hyphecan (1‐4,2‐acetamide‐deoxy‐B ‐D ‐glucan polymer) on wound healing in a rodent model. Materials and Method: The prospective study was conducted at a basic science laboratory at a tertiary teaching hospital. Two 4 cm × 4 cm full‐thickness wounds were created on the dorsal surface of 10 Spraque–Dawley rats and covered with Hyphecan and Kaltostat, respectively. Wounds were examined and measured on days 4, 10, 21 and 28, and would continue after day 28 until healed up completely. Punch biopsies (3 mm) were taken on days 4, 10 and 28 for histological examination of the response of healing and repair. Results: Despite the fact that the wound healing rate was similar for both groups on days 4, 10, 21 and 28, the average healing time for the Hyphecan group (29.1 ± 1.7 days) was significantly shorter statistically (P = 0.03) than the Kaltostat group (30.7 ± 2.8 days). Conversely, the marked healing response elicited by Hyphecan on day 4 persisted on days 10 and 28 in contrast to Kaltostat, which had only a mild degree of healing response on days 10 and 28. The study suggests that wounds treated by Hyphecan heal faster than Kaltostat. Conclusion: The findings provide basic scientific evidence supporting the clinical use of Hyphecan in different wounds and might also reduce the cost of wound management as Hyphecan is cheaper than Kaltostat and requires a shorter treatment time.      

A prospective randomized study of 980 nm diode laser‐assisted venous ulcer healing on 34 patients

Venous ulcers are chronic wounds affecting up to 1% of adults in developed countries. Considering that noncontact normothermic therapy has been shown to modify the wound healing process, we conducted a prospective comparative clinical trial aimed at evaluating 980 nm diode laser in laser‐assisted venous ulcer healing. Thirty‐four Caucasian patients with venous leg ulcers were included in the study and separated into two homogenous groups based on age, sex ratio, size, and etiologies of the ulcers. In the laser group, 980 nm InGasAs diode laser (power 15 W, spot size 8 mm, time 3 seconds, fluence 90 J/cm²) was applied weekly for 9 weeks to the ulcers in a homogenous standardized manner, resulting in a local temperature of 45–50 °C, which was controlled with a thermal infrared camera. Complete healing, reduction in size, and pain during and between each procedure were evaluated each time. Of the 18 patients in the laser group, three (16.7%) were completely healed during laser treatment. In the control group (16 patients), the healing was complete for four patients (25%). This difference was not significant (p=0.62). At the ninth follow‐up visit, in the control group, the ulcers had decreased on an average to 94.3% of the original area of the ulcers. In the laser group, the decrease was to 74.2% of the original area of the ulcers. Again, this difference was not significant (p=0.60). The mean VAS score between each treatment was 2.7 (0.5–4.4) in the laser group compared with 3.8 (2.3–5.0) in the control group (0.13<p<0.86). During the treatment, the mean VAS score was 1.8 (0.2–3.8) in the laser group compared with 3.8 (2.1–6.0) in the control group (0.08<p<0.67). 980 nm diode laser‐assisted venous ulcer healing was easy to perform and very well tolerated. However, there were no statistically significant differences in reduction of ulcer size between the two groups, suggesting that this particular laser regimen does not promote wound healing. Additional studies involving larger patient populations and an increased frequency of treatment should be performed to confirm our initial conclusions.     

A human skin equivalent burn model to study the effect of a nanocrystalline silver dressing on wound healing

In this study, a deep burn wound model was established using a 3D human skin equivalent (HSE) model and this was compared to native skin. HSEs were constructed from dermis derived from abdominoplasty/breast surgery and this dermal template was seeded with primary keratinocytes and fibroblasts. The HSE model was structurally similar to native skin with a stratified and differentiated epidermis. A contact burn (60 °C, 80 °C, 90 °C) was applied with a modified soldering iron and wounds were observed at day 1 and 7 after burn. The HSEs demonstrated re-growth with keratinocyte proliferation and formation of a neo-epidermis after burn injury, whereas the ex vivo native skin did not. To assess the suitability of the 3D HSE model for penetration and toxicity studies, a nanocrystalline silver dressing was applied to the model for 7 days, with and without burn injury. The effect of silver on skin re-growth and its penetration and subcellular localization was assessed in HSEs histologically and with laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The silver treatment delayed or reduced skin re-growth, and silver particles were detected on the top of the epidermis, and within the papillary dermis. This novel in vitro 3D multicellular deep burn wound model is effective for studying the pathology and treatment of burn wound injury and is suitable for penetration and toxicity studies of wound healing treatments.     

Fractional laser‐assisted delivery of methyl aminolevulinate: Impact of laser channel depth and incubation time

Background and Objectives

Pretreatment of skin with ablative fractional lasers (AFXL) enhances the uptake of topical photosensitizers used in photodynamic therapy (PDT). Distribution of photosensitizer into skin layers may depend on depth of laser channels and incubation time. This study evaluates whether depth of intradermal laser channels and incubation time may affect AFXL‐assisted delivery of methyl aminolevulinate (MAL).

Materials and Methods

Yorkshire swine were treated with CO₂ AFXL at energy levels of 37, 190, and 380 mJ/laser channel and subsequent application of MAL cream (Metvix®) for 30, 60, 120, and 180 minutes incubation time. Fluorescence photography and fluorescence microscopy quantified MAL‐induced porphyrin fluorescence (PpIX) at the skin surface and at five specific skin depths (120, 500, 1,000, 1,500, and 1,800 µm).

Results

Laser channels penetrated into superficial (～300 µm), mid (～1,400 µm), and deep dermis/upper subcutaneous fat layer (～2,100 µm). Similar fluorescence intensities were induced at the skin surface and throughout skin layers independent of laser channel depth (180 minutes; P < 0.19). AFXL accelerated PpIX fluorescence from skin surface to deep dermis. After laser exposure and 60 minutes MAL incubation, surface fluorescence was significantly higher compared to intact, not laser‐exposed skin at 180 minutes (AFXL‐MAL 60 minutes vs. MAL 180 minutes, 69.16 a.u. vs. 23.49 a.u.; P < 0.01). Through all skin layers (120–1,800 µm), laser exposure and 120 minutes MAL incubation induced significantly higher fluorescence intensities in HF and dermis than non‐laser exposed sites at 180 minutes (1,800 µm, AFXL‐MAL 120 minutes vs. MAL 180 minutes, HF 14.76 a.u. vs. 6.69 a.u. and dermis 6.98 a.u. vs. 5.87 a.u.; P < 0.01).

Conclusions

AFXL pretreatment accelerates PpIX accumulation, but intradermal depth of laser channels does not affect porphyrin accumulation. Further studies are required to examine these findings in clinical trials. Lasers Surg. Med. 44: 787–795, 2012. © 2012 Wiley Periodicals, Inc.     

Wound healing in Mac‐1 deficient mice

Mac‐1 (CD11b/CD18) is a macrophage receptor that plays several critical roles in macrophage recruitment and activation. Because macrophages are essential for proper wound healing, the impact of Mac‐1 deficiency on wound healing is of significant interest. Prior studies have shown that Mac‐1^?/? mice exhibit deficits in healing, including delayed wound closure in scalp and ear wounds. This study examined whether Mac‐1 deficiency influences wound healing in small excisional and incisional skin wounds. Three millimeter diameter full thickness excisional wounds and incisional wounds were prepared on the dorsal skin of Mac‐1 deficient (Mac‐1^?/?) and wild type (WT) mice, and wound healing outcomes were examined. Mac‐1 deficient mice exhibited a normal rate of wound closure, generally normal levels of total collagen, and nearly normal synthesis and distribution of collagens I and III. In incisional wounds, wound breaking strength was similar for Mac‐1^?/? and WT mice. Wounds of Mac‐1 deficient mice displayed normal total macrophage content, although macrophage phenotype markers were skewed as compared to WT. Interestingly, amounts of TGF‐β1 and its downstream signaling molecules, SMAD2 and SMAD3, were significantly decreased in the wounds of Mac‐1 deficient mice compared to WT. The results suggest that Mac‐1 deficiency has little impact on the healing of small excisional and incisional wounds. Moreover, the findings demonstrate that the effect of single genetic deficiencies on wound healing may markedly differ among wound models. These conclusions have implications for the interpretation of the many prior studies that utilize a single model system to examine wound healing outcomes in genetically deficient mice.     

Functional characterisation of bioactive peptide derived from terrestrial snail Cryptozona bistrialis and its wound‐healing property in normal and diabetic‐induced Wistar albino rats

A peptide might be an exciting biomaterial or template for the development of novel wound‐healing agents. In this report, it was isolated from the terrestrial snail Cryptozona bistrialis by enzymatic digestion and was evaluated for its in vitro wound‐healing activity in NIH/3T3 mouse fibroblasts cell line and in vivo wound‐healing activity in normal and diabetic‐induced Wistar albino rats. The C. bistrialis protein was digested by the papain enzyme, and 21.79 kDa peptide (Cb‐peptide) was purified by reversed‐phase high‐performance liquid chromatography and identified by MALDI (matrix‐assisted laser desorption/ionization)‐TOF analysis. The isolated Cb‐peptide was characterised by various analytical methods. The peptide demonstrated a capacity to prevent the development of pathogenic bacterial and fungal cultures and proved that it promotes significant wound‐healing activity in the wound scratch assay method by rapid cell migration and closure of wound. Isolated Cb‐peptide was lyophilised and formulated to ointment and analysed for in vivo wound‐healing activity in normal and diabetic (alloxan monohydrate)‐induced Wistar albino rats. Cb‐peptide ointment‐treated groups showed a greater degree of wound healing and early and complete period of epithelialisation in normal and diabetic‐induced Wistar albino rats. Cb‐peptide ointment‐treated groups showed significant excision and incision wound‐healing activity. A conclusion was reached that the peptide isolated from C. bistrialis showed greater wound‐healing activity compared with vehicle control and standard control.