Uremic pruritus and burn wounds
A randomized, double-blind, placebo-controlled 6-week study in 2012 conducted by Aramwit et al. assessed the use of sericin cream versus a cream base placebo in the treatment of uremic pruritus in 50 hemodialysis patients, 47 of whom completed the study. Significant differences in the creams were identified, with hydration vastly improved in patients using the sericin cream. Significant reductions in pruritus and dyspigmentation were also observed in the treatment group, with an overall quality of life improvement noted in relation to pain score.10
Gail Hampshire/Wikimedia Commons CC BY 2.0
The ensuing year, Aramwit et al. showed that silk sericin promoted wound healing in vitro and, when added to silver sulfadiazine cream and evaluated in a randomized, double-blind, standard-controlled study, demonstrated clinical efficacy in healing burn wounds.11
Wound healing
An expanding body of research suggests the role of sericin in wound healing. In 2007, Aramwit et al. found that sericin, which boasts notable hydrophilic qualities, was effective as a wound-healing agent in rats. The tested sericin cream successfully reduced wound size and wound healing time was substantially shorter than in animals treated with control formula. Treatment for 15 days yielded complete healing, no ulceration, and higher collagen levels, as determined by histologic examination, in comparison with control.12 Other studies using sericin hydrogel as well as a sericin-based nanofibrous matrix with chitosan have demonstrated success in wound healing in mice.13,14
Human studies
In 2018, Napavichayanun et al. reported on the clinical efficacy and safety of bacterial cellulose wound dressings including silk sericin and PHMB as compared with Bactigras (an antiseptic dressing) as a control in split-thickness skin graft donor-site wound treatment. In this single-blinded, randomized, controlled study of 21 patients, pain scores were significantly lower and wound quality higher in the skin treated with the sericin product. The test formulation was protected against infection without inducing adverse effects.15
Previously, a silk sericin–releasing wound dressing introduced in 2014 was found to significantly diminish pain and promote more rapid healing in patients with split-thickness skin graft donor sites as compared with treatment with the Bactigras wound dressing.16
Sericin in tissue repair and as a drug delivery carrier
Sericin is associated with antioxidant and moisturizing properties as well as a mitogenic influence on mammalian cells, with a particular impact on keratinocytes and fibroblasts that render it useful in biomaterials designed for skin tissue repair.17
Dr. Leslie S. Baumann
Wang et al. have cross-linked dialdehyde carboxymethyl cellulose with silk sericin derived from the B. mori cocoon to develop a film with impressive blood compatibility and cytocompatibility that shows potential for use as a wound dressing, artificial skin, and in tissue engineering.18
Similarly, Liang et al. have been successful in preparing a medical tissue glue incorporating a gelatin, sericin, and carboxymethyl chitosan blend solution, cross-linked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. The tissue glue has been found to offer notable biocompatibility and structural traits at low cost.19
Sericin protein also evinces potential as a biocompatible, bioviable carrier for drug delivery. Suktham et al. showed that resveratrol-loaded sericin nanoparticles robustly hindered growth of colorectal adenocarcinoma cells while cytotoxic to skin fibroblasts, suggesting the viability or potential of sericin nanoparticles as bionanocarriers in a drug delivery system.20 In addition, Tao et al. found silk sericin to be effective when blended with poly(vinyl alcohol) in a hydrogel with antibacterial properties as a drug delivery carrier with potential for use as wound dressing.21
Conclusion
Much more research is necessary, though, to explore how the antioxidant and moisturizing activities of the protein may be harnessed to confer skin-protective effects, especially against UV damage.
Dr. Baumann is a private practice dermatologist, researcher, author, and entrepreneur who practices in Miami. She founded the Cosmetic Dermatology Center at the University of Miami in 1997. Dr. Baumann wrote two textbooks: “Cosmetic Dermatology: Principles and Practice” (New York: McGraw-Hill, 2002), and “Cosmeceuticals and Cosmetic Ingredients” (New York: McGraw-Hill, 2014), and a New York Times Best Sellers book for consumers,“The Skin Type Solution” (New York: Bantam Dell, 2006). Dr. Baumann has received funding for advisory boards and/or clinical research trials from Allergan, Evolus, Galderma, and Revance. She is the founder and CEO of Skin Type Solutions Franchise Systems. Write to her at dermnews@mdedge.com
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