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01.12.2017 | Research | Ausgabe 1/2017 Open Access

European Journal of Medical Research 1/2017

Microneedle physical contact as a therapeutic for abnormal scars

Zeitschrift:
European Journal of Medical Research > Ausgabe 1/2017
Autoren:
David C. Yeo, Elizabeth R. Balmayor, Jan-Thorsten Schantz, Chenjie Xu
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​s40001-017-0269-6) contains supplementary material, which is available to authorized users.

Abstract

Background

Abnormal (keloid and hypertrophic) scars are a significant affliction with no satisfactory single modality therapy to-date. Available options are often ineffective, painful, potentially hazardous, and require healthcare personnel involvement. Herein a self-administered microneedle device based on drug-free physical contact for inhibiting abnormal scars is reported. Its therapeutic activity through microneedle contact eliminates hazards associated with toxic anti-scarring drugs while self-treatment enables administration flexibility.

Methods

The microneedle patch was fabricated with FDA-approved liquid crystalline polymer under good manufacturing practice. It was first tested to ascertain its ability to inhibit (keloid) fibroblast proliferation. Later the microneedle patch was examined on the rabbit ear hypertrophic scar model to explore its potential in inhibiting the generation of abnormal scars post-injury. Finally, the microneedle patch was applied to the caudal region of a hypertrophic scar located on a female patient’s dorsum to verify clinical efficacy.

Results

On untreated control cultures, barely any non-viable fibroblasts could be seen. After 12-h treatment with the microneedle patch, the non-viable proportion increased to 83.8 ± 11.96%. In rabbit ear hypertrophic scar model, 100% of the control wounds without the presence of patches on rabbit ears generated regions of raised dermis originating from the wound site (3/3), whereas microneedle treatment prevented dermis tissue thickening in 83.33% of the wounds (15/18). In the clinical test, the microneedle patch was well tolerated by the patient. Compared to the untreated region, microneedle treatment decreased the number of infiltrated inflammatory cells, with less disrupted dermis tissue architecture and more flattened appearance.

Conclusions

A self-administered, drug-free microneedle patch appears highly promising in reducing abnormal scarring as observed from in vitro, in vivo and clinical experiments. Larger cohort clinical studies need to be performed to validate its efficacy on abnormal scars.
Zusatzmaterial
Additional file 1: Figure S1. Microneedle contact and material cytotoxicity on fibroblasts. A) Representative phase contrast, blue and red fluorescence images of control and microneedle-treated normal fibroblasts (NF) incubated with Hoechst 33342 (blue) and propidium iodide (red). B) Fraction (%) of dead cells to total cells for the following studied groups: untreated control of normal fibroblasts (NF_C), normal fibroblasts cultured in presence of the microneedles but avoiding direct contact with the needles (NF_LCP) and microneedle-treated normal fibroblasts (NF_microneedle). The group NF_LCP aimed to evaluate the intrinsic toxicity of the material. For this, the microneedles were fixated to the walls of the well of the cell culture plate and immersed on the medium (schematically represented in B). C) Comparison of untreated control and microneedle-treated cells for keloids fibroblasts (KF) and normal fibroblasts (NF). Statistical significance has been indicated with *p < 0.01. Figure S2. Microneedles induce increased cell death. A) Representative images and B) quantification of dead Keloid Fibroblast (KF) cells per total cells in untreated controls and microneedle-treated cells. Quantification (B) was performed within the indicated (dotted lines) region of interest (ROI). The ROI was selected based on the region in which the microneedles were applied. This ROI from microneedle-treated samples was overlaid on the images of the untreated controls in order to have comparable ROI for quantification purposes. The used microscopic images were taken under identical fluorescence conditions and using the same magnification. Dead cells are propidium (PI—red)-labeled and total cells are Hoechst 33342 (blue)-labeled. Statistical significances are indicated with **p < 0.01, N = 3, values are mean ± SD. Figure S3. Quantified microneedle efficacy through the scar elevation index. A) SEI—scar elevation index measured on untreated & microneedle treated rabbit ear wounds. Representative untreated (B) and microneedle treated (C) wounds with the (---) region demarcating the raised neodermis and the (―) region signifying the original boundary where the wound was inflicted. *P < 0.01, N = 3.
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