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Year : 2018  |  Volume : 32  |  Issue : 2  |  Page : 87-90

Therapeutic potential of silicone gel sheet treatment and alteration in transforming growth factor beta gene expression in hypertrophic scars

Department of Plastic Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India

Date of Web Publication25-Oct-2018

Correspondence Address:
Dr. Pradeep Jain
Department of Plastic Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221 005, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jms.jms_12_17

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Background: The management and prevention of hypertrophic scars is a challenging problem. Various efforts are made by the researchers to understand the mechanism of the abnormal healing and also to offer better therapy to control these unusual scars. Silicone gel sheet is widely used as the first-line therapy for hypertrophic scars.
Objective: The present study has been designed to find out the efficacy of silicone gel sheet treatment on transforming growth factor beta gene(s) expression.
Subjects and Methods: The total RNA was isolated from forty hypertrophic scar cases with median age of 42 years before starting the treatment and at 6 months after the silicone gel sheet therapy using Trizol. The cDNA was synthesized for the quantitative gene expression analysis of transforming growth factor beta gene (1, 2, and 3) by real-time polymerase chain reaction.
Results: The observations showed that the mRNA expression of transforming growth factor beta (TGF β)-1 and -2 gene in hypertrophic scars was much higher, i.e., 2.6- and 3.8-fold, respectively, when evaluated and compared with controls. The present study also evaluated the efficiency of silicone gel sheet treatment therapy in hypertrophic scars in relation to altered expression of TGF-beta genes. After 6 months of therapy, the mRNA expression of TGF β-2 gene was significantly downregulated (P = 0.01) and β-3 insignificantly upregulated. Patients' assessment scale showed complete cure in 12.5% of cases, and major improvement was observed in 45% of cases.
Conclusion: The silicone gel sheet therapy is useful for treating the hypertrophic scars by downregulating expression of profibrotic TGF β-1 and -2 genes.

Keywords: Hypertrophic scar, silicone gel sheet, transforming growth factor beta

How to cite this article:
Gupta J, Jain V, Jain P. Therapeutic potential of silicone gel sheet treatment and alteration in transforming growth factor beta gene expression in hypertrophic scars. J Med Soc 2018;32:87-90

How to cite this URL:
Gupta J, Jain V, Jain P. Therapeutic potential of silicone gel sheet treatment and alteration in transforming growth factor beta gene expression in hypertrophic scars. J Med Soc [serial online] 2018 [cited 2021 Oct 26];32:87-90. Available from:

  Introduction Top

Hypertrophic scarring results from aberrant behavior of the normal process of wound healing. In human skin, it is characterized by excessive deposition of collagen in the dermis. However, in burn victims, the wound healing process may lead to the production of overabundant extracellular matrix, resulting in a raised hypertrophic scar. They are easily identified by color mismatch, stiffness, and rough texture. Hypertrophic scars affect 1.5%–4.5% of the general population. However, the exact prevalence of hypertrophic scarring in burn victims is really unknown. The incidence of hypertrophic scar following injuries has been reported in a range varying from 32% to 94%; 40%–94% following surgery and 30%–91% following burns.[1],[2],[3] The prevalence of hypertrophic scar is more in developing countries like India due to delayed surgical intervention, poor economy, and less literacy.[4] Many factors that influence the severity of hypertrophic scar are genetic predisposition, race, anatomical location of the burn, age, and depth of the burn.[5]

Growth factors are the substances that promote tissue repair and influence the reactivity of vascular and other blood cells in angiogenesis and inflammation. Cytokines play important role primarily as mediators of inflammatory and immunomodulatory reactions. Transforming growth factor beta (TGF-β) isoforms have different biological activities in wound healing and also play an important role in the pathogenesis of hypertrophic scarring through distinct molecular mechanisms.[6],[7],[8] Both TGF β-1 and TGF β-2 promote fibrosis and scar formation, whereas TGF β-3 is neither scar inducing nor reducing.[9],[10],[11],[12]

Burn injury outcome has improved significantly in recent years in relation to survival and patient rehabilitation. However, the treatment of hypertrophic scars still remains a major problem for clinicians. In the present era, various treatment modalities are available for the prevention and management of hypertrophic scar. Silicone gel sheets are widely used as the first-line therapy for hypertrophic scars as published in international guidelines on scar management.[13] Silicone materials are synthetic polymers based generally on a dimethylsiloxane monomer. The treatment with silicone gel sheet should begin about 2 weeks after complete healing of wound.[14],[15] It is applied directly on the scar without any pressure and remains in contact with the skin surface as long as possible.[16] The duration of silicone gel sheet application usually ranges from 12 to 24 h daily, after which it needs to be washed and reapplied.[17] It has no effect on oxygen tension, pressure, and scar temperature. The silicone gel sheet is impermeable to water, increased skin hydration probably is responsible for decrease in capillary activity and reduced collagen deposition and scar hypertrophy.[18]

The present study was carried out to demonstrate the molecular changes in hypertrophic scars following the use of silicone gel sheet treatment, i.e., alteration in expression of transforming growth factor β which is considered largely to be profibrotic.

  Subjects and Methods Top

We studied forty cases (median age 42 years, range 10–70 years) of postburn hypertrophic scar. The control group consisted of thirty unrelated, age- and sex-matched healthy individuals. All the patients with hypertrophic scar ≥18 months old in duration were included in the study and were followed up for 6 months with the silicone gel sheet application. Tissue biopsies before and after the therapy were collected from tertiary care teaching institute. The Institute's Ethical Committee approved the protocol, and informed written consent was obtained from the attendants/patients in each case.

Silicone gel sheet (Nagor, USA) was applied over the hypertrophic scar continuously with an ½ h break before and after bath for the period of 23 h in a day. The patients were taught how to apply, clean, and maintain the integrity of gel sheet.

Real-time polymerase chain reaction (RT-PCR) analyses were performed in a fluorescence temperature thermal cycler (Minicycler, Biored, USA) according to the manufacturer's instructions. Total RNA from tissue biopsies was isolated using Trizol reagent (Sigma, USA). 2 μg of total RNA was reverse transcribed using standard reagents (Invitrogen, USA). The cDNA served as a template in a 10 μl reaction containing 0.5 mM of each primer of TGF-beta gene (1, 2, and 3) and 2x Sybergreen mix (Biored, USA). Samples were incubated for an initial denaturing at 95°C for 10 min. It was followed by 45 cycles with each cycle consisting of 95°C for 10 s, 60°C for 10 s, and 72°C for 10s. Cycle-to-cycle fluorescence emission readings were monitored at 72°C at the end of each cycle. Melting curves were generated after each run to confirm amplification of specific gene(s). All quantifications were normalized to the housekeeping gene β-actin.

The gene expression data are reported as means ± standard deviation. The mean difference between pre- and post-treatment data was analyzed using paired t-test. All statistical analyses were performed using SPSS version 21.0 (IBM Corp., Armonk, NY, USA). Values were considered significant at P < 0.05.

The patients were asked to rate their scars as per “Patient and Observer Scar Assessment Scale (POSAS)”[19] on the basis of six parameters: pain, itching, color, stiffness, thickness, and surface irregularity. Each parameter was assessed by using a ten-point scoring system with our little modification, 1 representing the score at the beginning of treatment with worst symptoms and 10 representing cure/utmost satisfaction. The patients who rated the results of the treatment as Grade 10 on the scale in the overall opinion were considered as cured/utmost satisfied, 9 to 6 grade as major improvement, 5 to 3 grade as minor improvement, and 1 to 2 as no response.

  Results Top

Expression of TGF β-1, -2, and -3 mRNA was investigated in hypertrophic scars and controls by RT-PCR as shown in [Figure 1]. The study showed that the pretreatment mRNA expression of TGF β-1 and TGF β-2 was increased up to 2.6- and 3.8-fold, respectively, in the hypertrophic scars when compared with controls, whereas the TGF β-3 gene had lower expression.
Figure 1: Real-time polymerase chain reaction was performed to detect the mRNA expression of transforming growth factor beta genes in cases (black bars) and in controls (white bars). The mRNA expression of transforming growth factor beta-2 gene was highest while β-3 gene showed lower expression data were normalized to β-actin endogenous control. Data are represented as means ± standard deviation

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In the posttreatment evaluation, the mRNA expression of TGF β-2 gene was found to be downregulated and it showed significant (P = 0.01) difference in the mean average (1.43-fold change) between pre- and post-therapy expression. The mRNA expression of TGF β-1 gene was not significantly decreased. Conversely, we observed that the mRNA expression of TGF β-3 gene was insignificantly upregulated as shown in [Table 1] and [Figure 2].
Table 1: Descriptive statistical results of t-test in hypertrophic scars before and after silicone gel sheets therapy

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Figure 2: Real-time polymerase chain reaction was performed to detect the relative expression of transforming growth factor beta (1, 2, and 3) genes in pretreatment (white bars) and after silicone gel sheet treatment (black bars) hypertrophic scar cases. Our study observed that after the treatment, the expression of β-2 was decreased significantly

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The Patients' Assessment Scale at 6 months of treatment showed complete cure in 12% of cases and major improvement was observed in 45% of cases [Figure 3].
Figure 3: After the treatment with silicone gel sheet, the patients showed different rate of response. 12% of cases cured completely while major improvement observed in 45% cases

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  Discussion Top

Understanding of the molecular and biological mechanisms involved in hypertrophic scar formation increased in recent years, and it also allowed the development of more specific therapeutic options for these lesions. The present study demonstrates the expression of TGF-β gene family in the hypertrophic scar before using any treatment modality and also after treatment with silicone gel sheet. Our investigations showed that the expression of TGF β-1 and -2 genes was increased, while that of TGF β-3 gene had low expression in hypertrophic scars before treatment when compared with controls. These findings are consistent with those of Lu et al.[20] who also showed an increased expression of TGF β-1 and -2 and a decreased expression of TGF β-3 in hypertrophic scars. The therapeutic effect of silicone gel sheeting in flattening, softening, and increasing the pliability of the scar and in keeping the skin adequately hydrated but not overhydrated due to impermeability to water has been well studied.[21],[22],[23],[24] Therefore, it was pertinent for us to find out the changes at the molecular level by measuring the TGF-β gene expression by quantitative gene expression analysis before and after treatment with silicone gel sheet. Our study observed that the mRNA expression of TGF β-2 was downregulated significantly (P < 0.05) but there was an insignificant decrease of β-1 and increase of β-3 gene expression following the silicone gel sheet application. Kuhn et al.[25] also showed that application of silicone gel sheet downregulated the expression of TGF β-2 gene. The different patterns of expression were observed between cases before and after 6 months of therapy. The discrepancy of the results observed could be due to different location of hypertrophic scars, age, sex, and duration. The hypertrophic scars, before the therapy, were reddish-pink, thick, and hard and became pale, flattened, and softer 6 months later in 92% of the patients with gel sheet application. It is hypothesized that there is decreased capillary activity which downregulates fibroblasts' activity, reduces collagen deposition and scar thickness.[24]

Contrary to the original scoring described in POSAS scale by Draaijers et al. in the year 2004, where 1 is the best and 10 the worst for each parameter, we reversed the order to enable the patients to easily assess and describe the degree of improvement. However, most of the patients were more concerned with the pain, itching, thickness, and color and therefore rated their overall response to the treatment accordingly.

  Conclusion Top

In the burn victims, the treatment and prevention of hypertrophic scars by the use of silicone gel sheet has become very imperative. Silicone gel sheet application does bring relief to the patients with hypertrophic scars by favorably altering the expression of profibrotic TGF β-1 and -2 with some increase in antifibrotic TGF β-3. In our opinion, the key to the success of this therapy is ensuring good hygiene by proper cleaning of the sheet and the scar. This helps in preventing irritation and infection at the site of gel sheet application and in prolonging the life of the sheet and also in reducing the cost of treatment.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Bombaro KM, Engrav LH, Carrougher GJ, Wiechman SA, Faucher L, Costa BA, et al. What is the prevalence of hypertrophic scarring following burns? Burns 2003;29:299-302.  Back to cited text no. 1
Li-Tsang CW, Lau JC, Chan CC. Prevalence of hypertrophic scar formation and its characteristics among the Chinese population. Burns 2005;31:610-6.  Back to cited text no. 2
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Gupta J, Patel A, Jain P. Alteration in transforming growth factor-β1gene expression in hypertrophic scar. Indian J Biotech 2014;13:314-7.  Back to cited text no. 4
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Roberts AB, Sporn MB, Assoian RK, Smith JM, Roche NS, Wakefield LM, et al. Transforming growth factor type beta: Rapid induction of fibrosis and angiogenesis in vivo and stimulation of collagen formation in vitro. Proc Natl Acad Sci U S A 1986;83:4167-71.  Back to cited text no. 10
Yang EY, Moses HL. Transforming growth factor beta 1-induced changes in cell migration, proliferation, and angiogenesis in the chicken chorioallantoic membrane. J Cell Biol 1990;111:731-41.  Back to cited text no. 11
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Mustoe TA, Cooter RD, Gold MH, Hobbs FD, Ramelet AA, Shakespeare PG, et al. International clinical recommendations on scar management. Plast Reconstr Surg 2002;110:560-71.  Back to cited text no. 13
Gilman TH. Silicone sheet for treatment and prevention of hypertrophic scar: A new proposal for the mechanism of efficacy. Wound Repair Regen 2003;11:235-6.  Back to cited text no. 14
Ricketts CH, Martin L, Faria DT, Saed GM, Fivenson DP. Cytokine mRNA changes during the treatment of hypertrophic scars with silicone and nonsilicone gel dressings. Dermatol Surg 1996;22:955-9.  Back to cited text no. 15
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Chan KY, Lau CL, Adeeb SM, Somasundaram S, Nasir-Zahari M. A randomized, placebo-controlled, double-blind, prospective clinical trial of silicone gel in prevention of hypertrophic scar development in median sternotomy wound. Plast Reconstr Surg 2005;116:1013-20.  Back to cited text no. 17
Niessen FB, Spauwen PH, Robinson PH, Fidler V, Kon M. The use of silicone occlusive sheeting (Sil-K) and silicone occlusive gel (Epiderm) in the prevention of hypertrophic scar formation. Plast Reconstr Surg 1998;102:1962-72.  Back to cited text no. 18
Draaijers LJ, Tempelman FR, Botman YA, Tuinebreijer WE, Middelkoop E, Kreis RW, et al. The patient and observer scar assessment scale: A reliable and feasible tool for scar evaluation. Plast Reconstr Surg 2004;113:1960-5.  Back to cited text no. 19
Lu L, Chen YL, Zhang QG. Distribution and expression of transforming growth factor beta and their receptors in hypertrophic scar. Zhonghua Shao Shang Za Zhi 2004;20:30-3.  Back to cited text no. 20
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Fulton JE Jr. Silicone gel sheeting for the prevention and management of evolving hypertrophic and keloid scars. Dermatol Surg 1995;21:947-51.  Back to cited text no. 22
Suetak T, Sasai S, Zhen YX, Tagami H. Effects of silicone gel sheet on the stratum corneum hydration. Br J Plast Surg 2000;53:503-7.  Back to cited text no. 23
Quinn KJ, Evans JH, Courtney JM, Gaylor JD, Reid WH. Non-pressure treatment of hypertrophic scars. Burns Incl Therm Inj 1985;12:102-8.  Back to cited text no. 24
Kuhn MA, Moffit MR, Smith PD, Lyle WG, Ko F, Meltzer DD, et al. Silicone sheeting decreases fibroblast activity and downregulates TGFbeta2 in hypertrophic scar model. Int J Surg Investig 2001;2:467-74.  Back to cited text no. 25


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]

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