Abstract
Excessive skin scars due to elective operations or trauma represent a challenging clinical problem. Pathophysiology of hypertrophic scars entails a prolonged inflammatory and proliferative phase of wound healing. Over expression of TGF-β1 and COX-2 play key regulatory roles of the aberrant fibrogenic responses and proinflammatory mediators. When we silenced TGF-β1 and COX-2 expression simultaneously in primary human fibroblasts, a marked increase in the apoptotic cell population occurred in contrast to those only treated with either TGF-β1 or COX-2 siRNA alone. Furthermore, using human hypertrophic scar and skin graft implant models in mice, we observed significant size reductions of the implanted tissues following intra-scar administration of TGF-β1/COX-2 specific siRNA combination packaged with Histidine Lysine Polymer (HKP). Gene expression analyses of those treated tissues revealed silencing of the target gene along with down regulations of pro-fibrotic factors such as α-SMA, hydroxyproline acid, Collagen 1 and Collagen 3. Using TUNEL assay detection, we found that the human fibroblasts in the implanted tissues treated with the TGF-β1/COX-2siRNAs combination exhibited significant apoptotic activity. Therefore we conclude that a synergistic effect of the TGF-β1/COX-2siRNAs combination contributed to the size reductions of the hypertrophic scar implants, through activation of fibroblast apoptosis and re-balancing between scar tissue deposition and degradation.
Highlights
Human hypertrophic scar reduction and management are major therapeutic challenges due to lack of in-depth understanding of the underlying mechanism and the few validated treatment strategies available [1]
We first designed scanning electron microscopy was conducted when Histidine-Lysine Polymer (HKP) (siRNA) sequences specific to human transforming growth factor-β1 (TGF-β1) and COX-2 mRNAs in silico and tested the efficacy of these sequences based on cell transfection and analysis using qRT-PCR (Tables 1–2)
When human fibroblasts isolated from the hypertrophic scar tissue were transfected with the selected siRNAs targeting either TGF-β1 or COX-2 individually or in combination, we observed an efficient siRNA entry (Supplementary Figure 1) into the cells at different stages, from initial endocytosis to endosome release of the siRNAs
Summary
Human hypertrophic scar reduction and management are major therapeutic challenges due to lack of in-depth understanding of the underlying mechanism and the few validated treatment strategies available [1]. Understanding the pathophysiology of fibrosis may lead to a novel therapeutic with improved clinical benefit [2]. Fibrosis is defined by excessive accumulation of extracellular matrix (ECM) in and around the damaged tissue, which can lead to permanent scarring [3]. Hypertrophic scar (HS) is the result of a disrupted balance between ECM protein deposition and degradation during the dermal wound healing process [4]. It is characterized by the prolonged inflammatory response to injury resulting in an increased vascularization, hypercellularity and excessive collagen www.impactjournals.com/oncotarget deposition from local fibroblasts [5]. Fibroblasts are the most common cells in connective tissue, playing a key role in the wound healing process and can differentiate into myofibroblasts that results in increased ECM synthesis and tissue contraction [6, 7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
