ABSTRACT
BACKGROUND: Hyaluronic acid (HA), a naturally occurring polysaccharide, is used in the production of dermal fillers for esthetic purposes. As it has a few days of half-life in human tissues, HA-based dermal filler is chemically modified to increase its lifetime in the body. The most common modification used in commercial HA-based filler is the cross-linking of HA chains using 1,4-butanediol diglycidyl ether (BDDE) as cross-linking agent. Residual, or unreacted, BDDE is considered nontoxic when it is <2 parts per million (ppm); therefore, the quantification of residual BDDE in the final dermal filler is mandatory to ensure the safety of the patients. MATERIALS AND METHODS: The present study describes the detection and characterization of one by-product of the cross-linking reaction between BDDE and HA in alkaline conditions by combining both liquid chromatography and mass spectroscopy (LC-MS). RESULTS: After different analyses, it was found that the alkaline conditions and the high temperatures employed to sterilize the HA-BDDE hydrogel promote the formation of this new by-product, a "propene glicol-like" compound. LC-MS analysis confirmed that this by-product have the same monoisotopic mass as that of BDDE, a different retention time (tR), and also a different UV absorbance (λ=200 nm) pattern. Unlike BDDE, it was observed in the LC-MS analysis that this by-product had a higher detection at 200 nm in the same assay conditions. CONCLUSION: These results suggest that this new compound does not have an epoxide on its structure. The discussion is open to assess the risk of this new by-product found in the production of HA-BDDE hydrogels (HA dermal fillers) for commercial purposes.
ABSTRACT
INTRODUCTION: Silanol (organic silicon) has been used for decades in the treatment of skin photoaging as it stabilizes and maintains skin structures through hydrogen bonding electrostatic interaction with extracellular matrix (ECM) proteins or glycosaminoglycans. Organic silicon-based products are often presented as silanol derivatives which are currently associated to other structural molecules such as orthohydroxybenzoate, carboxymethyl theophylline alginate, ascorbate, acetyltyrosine, sodium lactate or mannuronate. Consequently, organic silicon formulations may differ substantially between the medical devices available on the market, which may result in additional effect on the skin. Therefore, there is a real need for a better characterization of the products in terms of their action on human skin and in vitro skin model. MATERIALS AND METHODS: In this in vitro study, the effect of RRS® Silisorg was analyzed. RRS® Silisorg is a dermal implant (CE Class III medical device) containing monomethylsilanol mannuronate associated to an antioxidant resveratrol. Skin fibroblast viability and capacity to induce the production of key ECM genes were evaluated in the presence of different concentrations of RRS® Silisorg. The key ECM genes selected were collagen type I, elastin and hyaluronan synthase type 2 (HAS2), which is the cellular enzyme responsible for high-molecular weight hyaluronic acid (HA) production. Viability was evaluated through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and expression was quantified by quantitative polymerase chain reaction. RESULTS: RRS® Silisorg increased fibroblast gene expression of HAS2 in the first 24 hours, 25 times in the presence of 1 mg/mL of solution, followed by a collagen type I gene expression (4.7 times) and elastin expression (2.5 times) increase after 48 hours. CONCLUSION: These results demonstrate that the silanol-based medical device RRS® Silisorg sustains HA, collagen and elastin production in human skin fibroblasts in vitro.
ABSTRACT
Mesotherapy/biorevitalization with hyaluronic acid (HA) is a treatment approach currently used for skin rejuvenation. Various products with a wide range of polycomponent formulations are available on the market. Most of these formulations contain noncross-linked HA in combination with a biorevitalization cocktail, formed by various amounts of vitamins, minerals, amino acids, nucleotides, coenzymes, and antioxidants. Although ingredients are very similar among the different products, in vitro and clinical effects may vary substantially. There is a real need for better characterization of these products in terms of their action on human skin or in vitro skin models. In this study, we analyzed the effect of the RRS(®) (Repairs, Refills, Stimulates) HA injectable medical device on human skin fibroblasts in vitro. Skin fibroblast viability and its capacity to induce the production of key extracellular matrix were evaluated in the presence of different concentrations of RRS HA injectable. Viability was evaluated through colorimetric MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, and key extracellular matrix genes, type I collagen and elastin, were quantified by quantitative polymerase chain reaction. Results demonstrated that RRS HA injectable could promote human skin fibroblast viability (+15%) and increase fibroblast gene expression of type I collagen and elastin by 9.7-fold and 14-fold in vitro, respectively. These results demonstrate that mesotherapy/biorevitalization products can, at least in vitro, effectively modulate human skin fibroblasts.
