Volume 49, Issue 7 pp. 675-685
Pre-Clinical Reports

Inflammatory responses, matrix remodeling, and re-epithelialization after fractional CO2 laser treatment of scars

Danielle M. DeBruler MS

Danielle M. DeBruler MS

Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio

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Britani N. Blackstone PhD

Britani N. Blackstone PhD

Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio

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Molly E. Baumann BS

Molly E. Baumann BS

Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio

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Kevin L. McFarland MS

Kevin L. McFarland MS

Department of Research, Shriners Hospitals for Children, Cincinnati, Ohio

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Brian C. Wulff PhD

Brian C. Wulff PhD

Department of Pathology, The Ohio State University, Columbus, Ohio

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Traci A. Wilgus PhD

Traci A. Wilgus PhD

Department of Pathology, The Ohio State University, Columbus, Ohio

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J. Kevin Bailey MD

J. Kevin Bailey MD

Department of Surgery, Division of Critical Care, Trauma and Burns, The Ohio State University, Columbus, Ohio

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Dorothy M. Supp PhD

Dorothy M. Supp PhD

Department of Research, Shriners Hospitals for Children, Cincinnati, Ohio

Department of Surgery, University of Cincinnati, Cincinnati, Ohio

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Heather M. Powell PhD

Corresponding Author

Heather M. Powell PhD

Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio

Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio

Correspondence to: Dr. Heather Powell, 243 Fontana Labs, 116 W. 19th Ave., Columbus, OH 43210.

E-mail: [email protected]

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First published: 10 May 2017
Citations: 44
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.

Abstract

Background and Objective

Fractional CO2 laser therapy has been used to improve scar pliability and appearance; however, a variety of treatment protocols have been utilized with varied outcomes. Understanding the relationship between laser power and extent of initial tissue ablation and time frame for remodeling could help determine an optimum power and frequency for laser treatment. The characteristics of initial injury caused by fractional CO2 laser treatment, the rates of dermal remodeling and re-epithelialization, and the extent of inflammation as a function of laser stacking were assessed in this study in a porcine scar model.

Materials and Methods

Full-thickness burn wounds were created on female Red Duroc pigs followed by immediate excision of the eschar and split-thickness autografting. Three months after injury, the resultant scars were treated with a fractional CO2 laser with 70 mJ of energy delivered as either a single pulse or stacked for three consecutive pulses. Immediately prior to laser treatment and at 1, 24, 96, and 168 hours post-laser treatment, transepidermal water loss (TEWL), erythema, and microscopic characteristics of laser injury were measured. In addition, markers for inflammatory cytokines, extracellular matrix proteins, and re-epithelialization were quantified at all time points using qRT-PCR.

Results

Both treatments produced erythema in the scar that peaked 24 hours after treatment then decreased to basal levels by 168 hours. TEWL increased after laser treatment and returned to normal levels between 24 and 96 hours later. Stacking of the pulses did not significantly increase the depth of ablated wells or extend the presence of erythema. Interleukin 6 and monocyte chemoattractant protein-1 were found to increase significantly 1 hour after treatment but returned to baseline by 24 hours post laser. In contrast, expression of transforming growth factor β1 and transforming growth factor β3 increased slowly after treatment with a more modest increase than interleukin 6 and monocyte chemoattractant protein-1.

Conclusions

In the current study, the properties of the ablative zones were not directly proportional to the total amount of energy applied to the porcine scars with the use of triple stacking, resulting in only minor increases to microthermal zone (MTZ) depth and width versus a single pulse. Re-epithelialization and re-establishment of epidermal barrier function were observed in laser treated scars by 48 hours post therapy. Finally, many of the inflammatory genes up-regulated by the laser ablation returned to baseline within 1 week. As a whole, these results suggest that microthermal zones created by FXCO2 treatment re-epithelialize rapidly with the inflammatory response to the laser induced injury largely resolved within 1 week post treatment. Further study is needed to understand the relationship between laser stacking and MTZ properties in human scars in order to evaluate the clinical applicability of the stacking technique. Lasers Surg. Med. 49:675–685, 2017. © 2017 Wiley Periodicals, Inc.

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