An in vitro priming step increases the expression of numerous epidermal growth and migration mediators in a tissue-engineering construct.

An FDA-approved, prototypic, living, bilayered skin construct (BSC) has been used for non-healing wounds. Using this particular construct as proof of principle, we hypothesized that an in vitro 'priming' step may enhance its repertoire of expression of key mediators and genes. The priming step used here was incubation in Dulbecco's modified Eagle's medium (DMEM) for 24 h at 37°C and 5% CO2 , with or without construct meshing. Microarray and ingenuity pathway analysis (IPA) showed that >1000 genes were overexpressed by the priming step, including interleukin 6 (IL-6), which plays important roles in wound healing. Genes highly overexpressed by priming were those involved in epidermal proliferation and migration. Quantitative real-time PCR (qRT-PCR), immunostaining and western blots verified the results. An epiboly assay (epidermal migration over dermis) showed that BSC epiboly was inhibited by IL-6 neutralizing antibody. Back wounds of nude mice were treated with primed or control BSCs for 3 days prior to harvesting; primed BSCs showed a significantly (p = 0.006) greater level of epidermal migration vs unprimed. Our study demonstrates that an in vitro priming step induces wound healing-related genes in the BSC, leading to a construct that could prove more effective in stimulating wound healing. Copyright © 2014 John Wiley & Sons, Ltd.

Evaluation of dermal pericapillary fibrin cuffs in venous ulceration using confocal microscopy.

Dermal pericapillary fibrin is a hallmark of venous disease and is thought to play a pathogenic role in the development of ulceration. However, the actual spatial configuration of pericapillary fibrin is unknown, and it remains unclear whether it truly represents a barrier that can impair physiological exchanges between the blood and dermis. Using confocal microscopy on tissue specimens taken from the edges of venous ulcers in six patients, we report a detailed analysis of dermal pericapillary fibrin deposits. Sections were evaluated with an antibody to human fibrinogen/fibrin and viewed, vertically and horizontally, with confocal microscopy. The distribution of fibrin deposition was highly variable and patchy, with areas of great intensity next to others of marginal intensity. Vertical cut sections showed the highest concentration of fluorescent material next to the lumen of dermal capillaries. Horizontal sections showed that maximal fluorescence was distributed at random. Our findings indicate that fibrin deposits in venous ulcers are patchy and discontinuous around dermal vessels. As such, these deposits are unlikely to act as a true and stable anatomic barrier as originally proposed. However, pericapillary fibrin may still act as a physiological barrier under conditions of poor blood flow where even marginal or patchy fibrin deposition might have a greater effect on the exchange of oxygen and other nutrients between blood and dermis.

Identity of Mesophilic Anaerobic Sporeformers Cultured from Recycled Cannery Cooling Water.

Chlorinated, recycled water for cooling of containers in still retorts was sampled over a 27-month period at one food processing plant. Of 274 samples taken, 28 contained mesophilic, anaerobic spores in numbers that ranged from 0.04-4.6/ml (MPN). Though all isolates were characterized as Clostridium species, 11% could not be matched with named species. Clostridium butyricum and Clostridium barati (synonyms: C. paraperfringens , C. perenne ) comprised 55% of isolates. Excepting Clostridium sticklandii , which is neither proteolytic nor saccharolytic, all isolates were saccharolytic. This contrasted with the finding of both proteolytic and saccharolytic clostridial spores in the municipal water feeding the recycle water reservoir. An apparent selection for saccharolytic strains could not be explained on the basis of published resistance of anaerobic spores to free available chlorine.