Chuan Cao

Investigating the role of P311 in the hypertrophic scar.

The mechanisms of hypertrophic scar formation are not fully understood. We previously screened the differentially expressed genes of human hypertrophic scar tissue and identified P311 gene as upregulated. As the activities of P311 in human fibroblast function are unknown, we examined the distribution of it and the effects of forced expression or silencing of expression of P311. P311 expression was detected in fibroblast-like cells from the hypertrophic scar of burn injury patients but not in peripheral blood mononuclear cells, bone marrow mesenchymal stem cells, epidermal cells or normal skin dermal cells. Transfection of fibroblasts with P311 gene stimulated the expression of alpha-smooth muscle actin (α-SMA), TGF-β1 and α1(I) collagen (COL1A1), and enhanced the contraction of fibroblast populated collagen lattices (FPCL). In contrast, interference of fibroblast P311 gene expression decreased the TGF-β1 mRNA expression and reduced the contraction of fibroblasts in FPCL. These results suggest that P311 may be involved in the pathogenesis of hypertrophic scar via induction of a myofibroblastic phenotype and of functions such as TGF-β1 expression. P311 could be a novel target for the control of hypertrophic scar development.

Genistein inhibits proliferation and functions of hypertrophic scar fibroblasts.

Hypertrophic scarring is abnormal proliferation of dermal fibroblasts and excessive deposition of extracellular matrix. To date, despite many studies, treatments have not been satisfactory. Genistein, a potent, specific inhibitor of tyrosine protein kinases (TPKs), has been proved to inhibit many kinds of tumour and some fibrotic diseases. The purpose of this study was to investigate the effects of genistein on the proliferation and functions of hypertrophic scar fibroblasts (HSFBs) and the mechanism by which genistein inhibits TPK signal transduction. The first effect was observed by methyl-thiazol-diphenyl-tetrazolium assay and the second by [gamma-(32)p] adenosine triphosphate incorporation assay. The results demonstrated that genistein inhibits the proliferation and function of HSFBs and changes the TPK signal transduction pathway, which can provide an experimental basis for treating HS with genistein.

Stromal cell-derived factor 1 (SDF-1) accelerated skin wound healing by promoting the migration and proliferation of epidermal stem cells

Epidermal stem cells could contribute to skin repair through the migration of cells from the neighboring uninjured epidermis, infundibulum, hair follicle, or sebaceous gland. However, little is known about the factors responsible for the complex biological processes in wound healing. Herein, we will show that the attracting chemokine, SDF-1/CXCR4, is a major regulator involved in the migration of epidermal stem cells during wound repair. We found that the SDF-1 levels were markedly increased at the wound margins following injury and CXCR4 expressed in epidermal stem cells and proliferating epithelial cells. Blocking the SDF-1/CXCR4 axis resulted in a significant reduction in epidermal stem cell migration toward SDF-1 in vitro and delayed wound healing in vivo, while an SDF-1 treatment enhanced epidermal stem cell migration and proliferation and accelerated wound healing. These results provide direct evidence that SDF-1 promotes epidermal stem cell migration, accelerates skin regeneration, and makes the development of new regenerative therapeutic strategies for wound healing possible.

shRNA targeting SFRP2 promotes the apoptosis of hypertrophic scar fibroblast

Hypertrophic scars result from a dysregulated process in wound healing. Although the basic mechanism is unclear, increased proliferation and decreased cell apoptosis are noticed in the development of hypertrophic scar. In previous study, we found that secreted frizzled-related protein 2 (SFRP2), which was associated with cell proliferation, apoptosis, and differentiation, was dramatically upregulated in hypertrophic scar (HS) tissue. In this study short hairpin RNA (shRNA) targeting SFRP2 was employed to characterize SFRP2 function in hypertrophic scar-derived fibroblasts (HSFb). Cell proliferation was assessed by MTT, dynamic growth curves, and BRDU assays. Meanwhile, Cell apoptosis was detected using fluorescence-activated cell sorting (FACS). Caspase-3 activity was assayed by spectrophotometry. Fibroblast populated collagen lattice (FPCL) model was employed to evaluate the contractility of HSFb. Further, real-time PCR and western blot were used to measure the mRNA and protein expressions of α-SMA in HSFb. In addition, mRNA levels of type I and III procollagen were assayed by quantitative real-time PCR. The results revealed that shRNA targeting SFRP2 significantly promoted the apoptosis of HSFb, while it had no effect on the cell proliferation. Decreased synthesis of a-smooth muscle actin (α-SMA) in HSFb and reduced contraction of fibroblasts in the FPCL model were observed. Quantitative RT-PCR suggested that the mRNAs of type I and III procollagen were significantly downregulated. In conclusion, as a novel anti-apoptosis gene, SPRP2 was present in hypertrophic scars. Importantly, shRNA targeting SFRP2 may provide a new approach to preventing the formation of HS.

MicroRNA-98 inhibits the cell proliferation of human hypertrophic scar fibroblasts via targeting Col1A1

BackgroundHypertrophic scarring (HS) is a severe disease, and results from unusual wound healing. Col1A1 could promote the hypertrophic scar formation, and the expression of Col1A1 in HS tissue was markedly higher than that in the normal. In present study, we aimed to identify miRNAs as post-transcriptional regulators of Col1A1 in HS.MethodsMicroRNA-98 was selected as the key miRNA comprised in HS. The mRNA levels of miR-98 in HS tissues and the matched normal skin tissues were determined by qRT-PCR. MTT and flow cytometry were used to determine the influence of miR-98 on cell proliferation and apoptosis of HSFBs, respectively. Col1A1 was found to be the target gene of miR-98 using luciferase reporter assay. Luciferase assay was performed to determine the relative luciferase activity in mimic NC, miR-98 mimic, inhibitor NC and miR-98 inhibitor with Col1A13′-UTR wt or Col1A13′-UTR mt reporter plasmids. The protein expression of Col1A1 in HSFBs after transfection with mimic NC, miR-98 mimic, inhibitor NC and miR-98 inhibitor were determined by western blotting.ResultsThe mRNA level of miR-98 in HS tissues was much lower than that in the control. Transfection of HSFBs with a miR-98 mimic reduced the cell viability of HSFBs and increased the apoptosis portion of HSFBs, while inhibition of miR-98 increased cell viability and decreased apoptosis portion of HSFBs. miR-98 inhibitor increased the relative luciferase activity significantly when cotransfected with the Col1A1-UTR reporter plasmid, while the mutant reporter plasmid abolished the miR-98 inhibitor-mediated increase in luciferase activity. Western blotting revealed that overexpression of miR-98 decreased the expression of Col1A1.ConclusionsOverexpression of miR-98 repressed the proliferation of HSFBs by targeting Col1A1.

High glucose inhibits ClC-2 chloride channels and attenuates cell migration of rat keratinocytes

Background Accumulating evidence has demonstrated that migration of keratinocytes is critical to wound epithelialization, and defects of this function result in chronic delayed-healing wounds in diabetes mellitus patients, and the migration has been proved to be associated with volume-activated chloride channels. The aim of the study is to investigate the effects of high glucose (HG, 25 mM) on ClC-2 chloride channels and cell migration of keratinocytes. Methods Newborn Sprague Dawley rats were used to isolate and culture the keratinocyte in this study. Immunofluorescence assay, real-time polymerase chain reaction, and Western blot assay were used to examine the expression of ClC-2 protein or mRNA. Scratch wound assay was used to measure the migratory ability of keratinocytes. Transwell cell migration assay was used to measure the invasion and migration of keratinocytes. Recombinant lentivirus vectors were established and transducted to keratinocytes. Whole-cell patch clamp was used to perform the electrophysiological studies. Results We found that the expression of ClC-2 was significantly inhibited when keratinocytes were exposed to a HG (25 mM) medium, accompanied by the decline of volume-activated Cl− current (ICl,vol), migration potential, and phosphorylated PI3K as compared to control group. When knockdown of ClC-2 by RNAi or pretreatment with wortmannin, similar results were observed, including ICl,vol and migration keratinocytes were inhibited. Conclusion Our study proved that HG inhibited ClC-2 chloride channels and attenuated cell migration of rat keratinocytes via inhibiting PI3K signaling.

RhoA promotes epidermal stem cell proliferation via PKN1-cyclin D1 signaling.

Objective Epidermal stem cells (ESCs) play a critical role in wound healing, but the mechanism underlying ESC proliferation is not well defined. Here, we explore the effects of RhoA on ESC proliferation and the possible underlying mechanism. Methods Human ESCs were enriched by rapid adhesion to collagen IV. RhoA(+/+)(G14V), RhoA(-/-)(T19N) and pGFP control plasmids were transfected into human ESCs. The effect of RhoA on cell proliferation was detected by cell proliferation and DNA synthesis assays. Induction of PKN1 activity by RhoA was determined by immunoblot analysis, and the effects of PKN1 on RhoA in terms of inducing cell proliferation and cyclin D1 expression were detected using specific siRNA targeting PKN1. The effects of U-46619 (a RhoA agonist) and C3 transferase (a RhoA antagonist) on ESC proliferation were observed in vivo. Results RhoA had a positive effect on ESC proliferation, and PKN1 activity was up-regulated by the active RhoA mutant (G14V) and suppressed by RhoA T19N. Moreover, the ability of RhoA to promote ESC proliferation and DNA synthesis was interrupted by PKN1 siRNA. Additionally, cyclin D1 protein and mRNA expression levels were up-regulated by RhoA G14V, and these effects were inhibited by siRNA-mediated knock-down of PKN1. RhoA also promoted ESC proliferation via PKN in vivo. Conclusion This study shows that the effect of RhoA on ESC proliferation is mediated by activation of the PKN1-cyclin D1 pathway in vitro, suggesting that RhoA may serve as a new therapeutic target for wound healing.

Inactivation of Beclin-1-dependent autophagy promotes ursolic acid-induced apoptosis in hypertrophic scar fibroblasts

A hypertrophic scar (HS) is caused by abnormal proliferation of dermal fibroblasts. Thus, promoting hypertrophic scar fibroblast (HSFB) apoptosis is an effective strategy for HS therapy. Ursolic acid (UA) has been widely used as an inducer of apoptosis in diverse cancers. However, whether UA plays an inhibitory role in HS formation is still unknown. In our study, UA was used to treat HSFBs and the cell viability, apoptosis, and collagen synthesis were determined by a Cell Counting Kit 8 assay, flow cytometry, and an H3‐proline incorporation assay, respectively. Autophagy activity was detected by LC3 immunoblotting and electron microscopy, and siRNAs targeting Beclin‐1 were used to inhibit autophagy. Western blotting was performed to investigate the molecular changes in HSFBs after various treatments. We found that UA inhibited collagen synthesis and induced cell apoptosis in HSFBs, evidenced by the deregulated expression of Bim, Bcl‐2 and Cyto C. Furthermore, we demonstrated that UA induced autophagy and inactivation of autophagy promoted UA‐induced apoptosis and collagen synthesis inhibition in HSFBs. Molecular investigation indicated that UA‐induced autophagy through upregulation of Beclin‐1 and knockdown of Beclin‐1 prevent UA‐induced autophagy. Overexpression of Bcl‐2 prevents UA‐induced autophagy, Beclin‐1 upregulation, apoptosis and collagen synthesis inhibition in HSFBs. Collectively, our study demonstrated that UA is a novel agent for inhibiting HS formation by promoting apoptosis, especially in combination with an autophagy inhibitor. Our results provide strong evidence of the application of UA in clinical HS treatment.

Down-Regulation of ClC-3 Expression Reduces Epidermal Stem Cell Migration by Inhibiting Volume-Activated Chloride Currents

ClC-3, a member of the ClC chloride (Cl−) channel family, has recently been proposed as the primary Cl− channel involved in cell volume regulation. Changes in cell volume influence excitability, contraction, migration, pathogen-host interactions, cell proliferation, and cell death processes. In this study, expression and function of ClC-3 channels were investigated during epidermal stem cell (ESC) migration. We observed differential expression of CLC-3 regulates migration of ESCs. Further, whole-cell patch-clamp recordings and image analysis demonstrated ClC-3 expression affected volume-activated Cl− current (ICl,Vol) within ESCs. Live cell imaging systems, designed to observe cellular responses to overexpression and suppression of ClC-3 in real time, indicated ClC-3 may regulate ESC migratory dynamics. We employed IMARIS software to analyze the velocity and distance of ESC migration in vitro to demonstrate the function of ClC-3 channel in ESCs. As our data suggest volume-activated Cl− channels play a vital role in migration of ESCs, which contribute to skin repair by migrating from neighboring unwounded epidermis infundibulum, hair follicle or sebaceous glands, ClC-3 may represent a new and valuable target for stem cell therapies.

Novel bilayer wound dressing composed of SIS membrane with SIS cryogel enhanced wound healing process

Full-thickness skin damage is a server issue and sometimes even dangerous to life. Many researches have been done toward full-thickness wound dressing. In this study, we demonstrated a facile and one-step procedure of SIS bilayer wound dressing. The top layer could protect the wound from bacterial infection and provide a moist environment suitable for wound healing, while the cryogel layer could promote cell proliferation. The SIS bilayer wound dressing has sufficient mechanical properties to protect wound from second damage and can maintain a moist environment for cell proliferation and migration at wound site. Bacterial permeation testing demonstrated that the bilayer scaffold had high efficiency in blocking bacteria at the wound site. In vivo tests and qRT-PCR results revealed that the bilayer group possessed a higher tendency toward keratinocyte proliferation and migration. The SIS bilayer has a high potential to use as full-thickness wound dressing.