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Hammer T.R.,Hohenstein Institutes | Mucha H.,Hohenstein Institutes | Hoefer D.,Hohenstein Institutes
Mycopathologia | Year: 2011

In the developed countries infections of the feet (tinea pedis, athlete's foot) and nails (onychomycosis) with the anthropophile fungus Trichophyton rubrum are most common. We examined the propagation of dermatophytes before and during domestic laundering. About 10% of the infectious material was transferred from contaminated textiles to sterile textiles during storage in a clothes basket simulation indicating a high infection risk during storage. This was evaluated with two quantification techniques: cultivation with subsequent colony counting and tracing of radioactively labelled propagating units. Both approaches reliably revealed similar results with the latter method reducing experimental time to few minutes compared to 2 weeks with the traditional method. The tracer technique allowed favourably to directly reflect the textile-bound infectious material at the moment of skin contact. To address the infection risk during domestic laundry, bioindicators with T. rubrum or the yeast Candida albicans were introduced into common domestic washing procedures with different temperature courses. While C. albicans did not survive any of the tests, T. rubrum could be recovered after washing at 30°C, indicating the risk potential of dermatophyte infections at home. Up to 16% of the initial fungus load was detected in the rinsing water. Washing at 60°C however, eliminated both pathogens, T. rubrum and C. albicans. © 2010 Springer Science+Business Media B.V. Source


Handel M.,Hohenstein Institutes | Hammer T.R.,Hohenstein Institutes | Hoefer D.,Hohenstein Institutes
Biomedical Materials (Bristol) | Year: 2012

Adipose tissue engineering, instead of tissue substitution, often uses autologous adipose tissue-derived stem cells (hASC). These cells are known to improve graft integration and to support neovascularization of scaffolds when seeded onto biomaterials. In this study we thought to engineer adipose tissue using scaffold-bound hASC, since they can be differentiated into the adipocyte cell lineage and used for soft tissue regeneration. We show here by microscopy and gene expression of the peroxysome proliferator-activated receptor gene (PPARγ2) that hASC growing on polypropylene fibrous scaffolds as well as on three-dimensional nonwoven scaffolds can be turned into adipose tissue within 19 days. Freshly isolated hASC displayed a higher differentiation potential than hASC cultured for eight passages. In addition, we proved a modified alginate microcapsule to directly induce adipogenic differentiation of incorporated hASC. The results may help to improve long-term success of adipose tissue regeneration, especially for large-scale soft tissue defects, and support the development of cell-scaffold combinations which can be shaped individually and directly induce the adipogenic differentiation of incorporated hASC at the site of implantation. © 2012 IOP Publishing Ltd. Source


Handel M.,Hohenstein Institutes | Hammer T.R.,Hohenstein Institutes | Nooeaid P.,Friedrich - Alexander - University, Erlangen - Nuremberg | Boccaccini A.R.,Friedrich - Alexander - University, Erlangen - Nuremberg | Hoefer D.,Hohenstein Institutes
Tissue Engineering - Part A | Year: 2013

Poor vascularization is the key limitation for long-term acceptance of large three-dimensional (3D) tissue engineering constructs in regenerative medicine. 45S5 Bioglass® was investigated given its potential for applications in bone engineering. Since native Bioglass® shows insufficient angiogenic properties, we used a collagen coating, to seed human adipose tissue-derived stem cells (hASC) confluently onto 3D 45S5 Bioglass ®-based scaffolds. To investigate vascularization by semiquantitative analyses, these biofunctionalized scaffolds were then subjected to in vitro human umbilical vein endothelial cells formation assays, and were also investigated in the chorioallantoic membrane (CAM) angiogenesis model, an in vivo angiogenesis assay, which uses the CAM of the hen's egg. In their native, nonbiofunctionalized state, neither Bioglass®-based nor biologically inert fibrous polypropylene control scaffolds showed angiogenic properties. However, significant vascularization was induced by hASC-seeded scaffolds (Bioglass® and polypropylene) in the CAM angiogenesis assay. Biofunctionalized scaffolds also showed enhanced tube lengths, compared to unmodified scaffolds or constructs seeded with fibroblasts. In case of biologically inert hernia meshes, the quantification of vascular endothelial growth factor secretion as the key angiogenic stimulus strongly correlated to the tube lengths and vessel numbers in all models. This correlation proved the CAM angiogenesis assay to be a suitable semiquantitative tool to characterize angiogenic effects of larger 3D implants. In addition, our results suggest that combinations of suitable scaffold materials, such as 45S5 Bioglass ®, with hASC could be a promising approach for future tissue engineering applications. © 2013 Mary Ann Liebert, Inc. Source


Hoefer D.,Hohenstein Institutes | Schnepf J.K.,Hohenstein Institutes | Hammer T.R.,Hohenstein Institutes | Fischer M.,University of Ulm | Marquardt C.,Regionale Kliniken Holding RKH GmbH
Journal of Materials Science: Materials in Medicine | Year: 2015

Marine alginate fibre dressings are well established in wound management. Alginate fibres can absorb plenty of wound exudate due to their gel forming abilities and ion exchange. Alginates from bacteria have never been studied for medical applications so far, although the microbial polymer raises expectations for improved gelling capacity due to its unique O-acetylation. To prove the gelling capacity of bacterial alginate, we extracted the co-polymer from fermentation of the soil bacterium Azotobacter vinelandii ATCC 9046, cultivated on crude glycerol as an alternative carbon source. Bacterial alginate was isolated in high purity and extruded by a wet spinning method. Fibre structure and properties were characterised by infrared spectroscopy, NMR, GPC, scanning electron microscopy and tensile testing. The fibres could be processed into biocompatible needle web dressings, which showed more than twice the gel formation in saline compared to commercial dressings made of marine alginates. Gelled dressings of bacterial alginate formed stable hydrogels of sufficient shape and strength for wound healing applications. This work suggests that the increased gel formation of bacterial alginate from A. vinelandii may be optimal for the preparation of novel wound dressings. © 2015, Springer Science+Business Media New York. Source


Hoefer D.,Hohenstein Institutes | Hohn G.,Hohenstein Institutes | Berner-Dannenmann N.,Hohenstein Institutes | Schulze T.,Thueringisches Institute fuer Textil und Kunststoff Forschung e.V. | And 2 more authors.
Open Medical Devices Journal | Year: 2011

Medicated wound dressings incorporate chemicals which have therapeutic value. The objective of this study was to investigate the in vitro model drug release from a biodegradable needle web, based on medicated cellulosic hollow fibres, which self-dissolve in the presence of aqueous solutions. Cellulose hollow fibres were prepared by a standard dry-wet phase inversion spinning process. Dressings were made using established techniques in the nonwoven industry. Two sets of hollow fibres were filled with different drug solutions: One set contained the enzyme cellulase and the second set was filled with either antibacterial Pseudomonas aeruginosaspecific bacteriophages, or the wound debriding enzyme Krillase ®. Both fibre sets were freeze-dried to (i) inactivate the spontaneous biodegradation of the fibres by cellulase and (ii) to preserve the wound healing activities of the biotherapeutic model drugs. Needle webs containing different mixing ratios of the two sets of hollow fibres were made. Whereas bacteriophages were released after rewetting the webs in in-vitro experiments with high burst effect, Krillase ® showed a sustained drug release over 20 h, which was found to be dependent on the mixing ratio of cellulase versus Krillase ®-hollow fibres. Possible release mechanisms and therapeutic benefits are discussed. In summary, needle webs of medicated cellulosic hollow fibres are a new self-dissolving drug delivery system. © Hoefer et al. Source

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