Novel dermo-epidermal equivalents on silk fibroin-based formic acid-crosslinked three-dimensional nonwoven devices with prospective applications in human tissue engineering/regeneration/repair

Abstract

Biologically well-tolerated materials are at the core of intense research. In this study, we report both the intrinsic features of formic acid (FA)-crosslinked threedimensional (3D) nonwoven scaffolds consisting of sericindeprived, Bombyx mori silk fibroin (SF) in ß-sheet form and the long-term co-culture of adult human epidermal keratinocytes (HEKs) and dermal fibroblasts (HDFs) on them. The results of scanning electron microscopy, differential scanning calorimetry, and thermogravimetric and tensile strength studies showed that such scaffolds are made by a composite material, in which anisotropic SF fibres are enclosed within an isotropic matrix of SF in film form. Both fibres and films are firmly crosslinked by FA treatment and water-insoluble owing to their ß-sheet crystalline structure. Moreover, while a certain strength of the material in the dry state may favour its manufacturing, handling, and shaping, the dramatic loss of hardiness under wet conditions renders the scaffolds softer, mechanically more compliant and, hence, more apt for implantation. Normal HEKs and HDFs could be successfully co-cultured on such nonwovens for up to 75-95 days in vitro, thus forming a novel kind of dermo-epidermal equivalent, in which the cells were metabolically active and performed specific functions (e.g. the de novo production and assembly of collagen fibres), but never released urea nitrogen (an index of protein catabolism) or proinflammatory interleukin-1ß (IL-1ß). In keeping with the results of previous studies in animals (Dal Pra I, et al, Biomaterials 26: 1987-1989, 2005), these findings support the view that 3D SF-based nonwovens may be excellent candidates for beneficial applications in the field of human tissue engineering/regeneration/repair.

Novel bilayer wound dressing composed of silicone rubber with particular micropores enhanced wound re-epithelialization and contraction

“…4), hence good biosecurity and biocompatibility of the large pore lower layer were demonstrated. More importantly, the capability of the wound dressing to promote cell adhesion and proliferation represents the potential effect of the dressing on promoting wound healing [24,25]. In our study, the lower layer was designed to contact the wound directly, and pore size of lower layer was designed to be larger than that of upper layer ( Fig.…”

Strategies for improving the physiological relevance of human engineered tissues

“…On the other hand, adipose differentiation was analyzed over a 6 month period by secretion of leptin and glycerol [7], while bone differentiation over a 46 day period was assessed by the presence of osteocalcin in the supernatant [8]. Additionally, glucose consumption (4 weeks [93], 10 weeks [94]), and lactate released [94] in the culture medium were non-invasive methods used to track cell metabolism over long culture periods.…”

In-vitro Characterization of Silk Sericin as an Anti-aging Agent

“…This study investigated one waste product from the silk industry, silk sericin, which is known to have moisturizing properties (Padamwar et al, 2005), protect against UV exposure and oxidation (Dash et al, 2008), form a protective film on the skin, hair, and nails (Dal-Pra et al, 2006;Zhang, 2002), aid in the wound-healing process (Aramwit & Sangcakul, 2007), and protect against cell death (Takahashi et al, 2003). Many products use this protein for various applications in the textile industry, cosmetics and cosmeceutical products, and food supplements (Zhang, 2002).…”