H. Worch

Max Bergmann Center of Biomaterials (MBC), Dresden, Saxony, Germany

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Publications (146)274.88 Total impact

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    ABSTRACT: Chitosan textile scaffolds are novel promising biomaterials for application in tissue engineering. The intro­duction of sulphate groups in the chitosan molecule leads to a biomaterial that combines two important features. At first it's an excellent material in order to build scaffolds for tissue engineering, and at second it is able to mimic the beneficial interaction of natural occurring sulphated polysaccharides with growth factors. Known sul­phating methods, developed for the sulphation of chitosan in solutions (homogeneous phase reactions), were adapted to apply them on solid chitosan surfaces (heterogeneous phase reactions). Surface reactions preventing the chitosan's dissolution were funda­mentally necessary to keep the predetermined geometric structure of the scaffolds during derivatization reactions. Model studies were carried out on chitosan particles as well as chitosan textiles. Points of interests were the control of the regio­selectivity of the sulphation reactions and the adjustment of the degree of sulphation. It was shown that a partial cross‐linking of chitosan is a key tool to keep the geometric structure of the chitosan particles and fibres during the subsequent sulphation reaction. The modified samples were comprehen­sively characterized by means of X‐ray photoelectron spectroscopy and elemental analysis.
    Macromolecular Symposia 12/2014; 346(1). DOI:10.1002/masy.201400067
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    ABSTRACT: In this study we investigated the potential of artificial extracellular matrix (aECM) coatings containing collagen II and two types of glycosaminoglycan (GAGs) with different degrees of sulphation to promote human bone formation in biomedical applications. To this end their impact on growth and osteogenic differentiation of human mesenchymal stem cells (hMSCs) was assessed. The cell proliferation was found to be significantly retarded in the first 14 days of culture on surfaces coated with collagen II and GAGs (coll-II/GAG) as compared to tissue culture polystyrol (TCPS) and those coated with collagen II. At later time points it only tended to be retarded on coll-II/sHya3.1. Heat-inactivation of the serum significantly reduced cell numbers on collagen II and coll-II/sHya3.1. Alkaline phosphatase (ALP) activity and calcium deposition, on the other hand, were higher for coatings containing sHya3.1 and were not significantly changed by heat-inactivation of the serum. Expression levels of the bone matrix proteins bone sialoprotein (BSP-II) and osteopontin (OP) were also increased on aECM coatings as compared to TCPS, which further validated the differentiation of hMSCs towards the osteogenic lineage. These observations reveal that aECM coatings, in particular those containing sHya3.1, are suitable to promote the osteogenic differentiation of hMSCs. Copyright © 2012 John Wiley & Sons, Ltd.
    Journal of Tissue Engineering and Regenerative Medicine 04/2014; 8(4). DOI:10.1002/term.1528 · 4.43 Impact Factor
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    ABSTRACT: In order to investigate the effects of different degrees of bioactivity of xerogels on connexin 43 (cx43) signaling of osteoclasts a cell culture approach was developed. Cells isolated from peripheral blood mononuclear cells were cultured in combination with the xerogels and were harvested for further investigations on day 1, day 5, and day 10. By means of quantitative PCR increased cx43 mRNA levels and coincident decreasing mRNA levels of the calcium sensing receptor, TRAP, and Cathepsin K were detected with increasing bioactivity of the xerogel samples. Additionally, osteoclasts cultured on tissue culture plates were used to perform principle investigations on cell differentiation by means of transmission electron microscopy, life cell imaging, and immunofluorescence, and the results demonstrated that cx43-signaling could be attributed to migration and fusion of osteoclast precursors. Therefore, the positive correlation of cx43 expression with high xerogel bioactivity was caused by proceeding differentiation of the osteoclasts. Finally, the presently observed pattern of cx43 signaling refers to strong effects regarding bioactivity on cx43-associated cell differentiation of osteoclasts influenced by extracellular calcium ions.
    Biomaterials 11/2013; DOI:10.1016/j.biomaterials.2013.11.002 · 8.31 Impact Factor
  • 01/2013; 14(3-4). DOI:10.1515/bnm-2013-0022
  • 01/2013; 14(3-4). DOI:10.1515/bnm-2013-0018
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    ABSTRACT: A human co-culture model of osteoblasts and osteoclasts, derived from bone marrow stromal cells and monocytes respectively, was used to characterize the influence of biomaterial modification on the bioactivity and ultimately the ratio of bone-forming to bone-resorbing cells cultivated directly on the surface. Nanocomposites of silica and collagen have been shown to function as skeletal structures in nature and were reproduced in vitro by using a sol-gel approach. The resulting xerogels exhibit a number of features that make it a valuable system for the development of innovative materials for bone substitution applications. In the present study, the incorporation of different calcium phosphate phases in silica/collagen-based gels was demonstrated to enhance the bioactivity of these samples. This ability of the biomaterial to precipitate calcium phosphate on the surface when incubated in simulated body fluids or cell culture medium is generally considered to an advantageous property for bone substitution materials. By co-cultivating human osteoblasts and osteoclasts up to 42days on the xerogels, we demonstrate that the long-term ratio of these cell types depends on the level of bioactivity of the substrate samples. Biphasic silica/collagen xerogels exhibited comparably low bioactivity but encouraged proliferation of osteoblasts in comparison to osteoclast formation. A balanced ratio of both cell types was detected for moderately bioactive triphasic xerogels with 5% calcium phosphate. However, enhancing the bioactivity of the xerogel samples by increasing the calcium phosphate phase percentage to 20% resulted in a diminished number of osteoblasts in favor of osteoclast formation. Quantitative evaluation was carried out by biochemical methods (calcium, DNA, ALP, TRAP 5b) as well as RT-PCR (ALP, BSP II, OC, RANKL, TRAP, CALCR, VTNR, CTSK), and was supported by confocal laser scanning microscopy (cell nuclei, actin, CD68, TRAP) as well as scanning electron microscopy.
    Acta biomaterialia 10/2012; DOI:10.1016/j.actbio.2012.10.010 · 5.68 Impact Factor
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    Chemie Ingenieur Technik 08/2012; 84(8). DOI:10.1002/cite.201250378 · 0.66 Impact Factor
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    ABSTRACT: Coatings of orthopedic implants are investigated to improve the osteoinductive and osteoconductive properties of the implant surfaces and thus to enhance periimplant bone formation. By applying coatings that mimic the extracellular matrix a favorable environment for osteoblasts, osteoclasts and their progenitor cells is provided to promote early and strong fixation of implants. It is known that the early bone ongrowth increases primary implant fixation and reduces the risk of implant failure. This review presents an overview of coating titanium and hydroxyapatite implants with components of the extracellular matrix like collagen type I, chondroitin sulfate and RGD peptide in different small and large animal models. The influence of these components on cells, the inflammation process, new bone formation and bone/implant contact is „summarized.
    07/2012; 2(3):149-157. DOI:10.4161/biom.21563
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    ABSTRACT: This study demonstrates that the modification of hyaluronan (hyaluronic acid; Hya) and chondroitin sulfate (CS) with sulfate groups leads to different binding affinities for recombinant human transforming growth factor-β1 (TGF-β1) for comparable average degrees of sulfation (DS). In general, Hya derivates showed higher binding strength than CS derivatives. In either case, a higher degree of sulfation leads to a stronger interaction. The high-sulfated hyaluronan sHya3 (average DS≈3) exhibited the tightest interaction with TGF-β1, as determined by surface plasmon resonance and enzyme-linked immunosorbent assay. The binding strength was significantly weakened by carboxymethylation. Unmodified Hya and low-sulfated, native CS showed weak or no binding affinity. The interaction characteristics of the different sulfated glycosaminoglycans are promising for incorporation into bioengineered coatings of biomaterials to modulate growth factor binding in medical applications.
    Acta biomaterialia 03/2012; 8(6):2144-52. DOI:10.1016/j.actbio.2012.03.021 · 5.68 Impact Factor
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    ABSTRACT: Biocorrodible iron foams were coated with different calcium phosphate phases (CPP) to obtain a bioactive surface and controlled degradation. Further adhesion, proliferation and differentiation of SaOs-2 and human mesenchymal stem cells were investigated under both static and dynamic culture conditions. Hydroxyapatite (HA; [Ca10(PO4)6OH2]) coated foams released 500 μg/g iron per day for Dulbecco's modified eagle medium (DMEM) and 250 μg/g iron per day for McCoys, the unmodified reference 1000 μg/g iron per day for DMEM and 500 μg/g iron per day for McCoys, while no corrosion could be detected on brushite (CaHPO4) coated foams. Using a perfusion culture system with conditions closer to the in vivo situation, cells proliferated and differentiated on iron foams coated with either brushite or HA while in static cell culture cells could proliferate only on Fe-brushite. We conclude that the degradation behaviour of biocorrodible iron foams can be varied by different calcium phosphate coatings, offering opportunities for design of novel bone implants. Further studies will focus on the influence of different modifications of iron foams on the expression of oxidative stress enzymes. Additional information about in vivo reactions and remodelling behaviour are expected from testing in implantation studies.
    Materials Science and Engineering B 12/2011; 176(20):1767–1772. DOI:10.1016/j.mseb.2011.06.004 · 2.12 Impact Factor
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    ABSTRACT: The combination of silica and collagen was identified in natural composites and recently recognized to be a valuable system for the preparation of innovative biomaterials for bone substitution applications. The present study reports on the development of silica/collagen composites, investigation of the underlying formation processes as well as further interactions with hydroxyapatite as a third phase. The possibilities and limitations of the material concept based on the sol-gel strategy were screened and characteristic composition ranges were identified. The gelation determining the processing time is strongly linked to the pH of silicic acid and collagen suspension mixtures as well as the buffer used and collagen concentration. The templating activity of collagen for silica formation is driven by primary amine groups as suggested by biochemical analysis and scanning electron microscopy. A high solid concentration in the initial hydrogels is essential in order to maintain the sample shape during transformation into monolithic and compact xerogels. The presence of fibrillar collagen significantly enhances the compressive strength of the xerogels up to 200 MPa and strain to fracture of up to 11%. The modular concept of the composite xerogel formation process allows incorporation of further phases such as calcium phosphate phases or prospectively drugs for the treatment of local or systemic diseases, opening large perspectives for the development of multifunctional bone implants.
    Composites Science and Technology 11/2011; 71(16). DOI:10.1016/j.compscitech.2011.08.023 · 3.63 Impact Factor
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    ABSTRACT: Zusammenfassung Wenn erworbene oder angeborene Knochendefekte aufgrund überkritischer Größe oder spezieller Krankheitsbilder (z. B. Osteoporose) nicht durch den natürlichen Regenerationsprozess geheilt werden können, ist der Einsatz von Knochenersatzmaterialien (KEM) notwendig. Hierbei handelt es sich um Materialien, die alleine oder im Zusammenwirken mit anderen Substanzen fehlenden Knochen im Empfängergewebe ersetzen und durch mechanische und strukturelle Unterstützung den Knochenheilungsprozess fördern. Diese unterstützende Wirkung kann sowohl von natürlichen als auch von artifiziellen KEM ausgehen und auf verschiedene Weise erfolgen. Oftmals wird die biologische Leistungsfähigkeit eines KEM mittels der Begriffe osteogene, osteokonduktive sowie osteoinduktive Stimulation diskutiert. Im Realfall kommt es jedoch meist zur Überschneidung mehrerer Wirkprinzipien. Aufgrund der begrenzten Verfügbarkeit von autologem Knochen und der mit dessen Entnahme verbundenen Nachteile für den Patienten wird intensiv an artifiziellen Alternativen geforscht. Der vorliegende Übersichtsartikel hat zum Ziel, durch systematische Darstellung der verschiedenen KEM, geordnet nach Werkstofftyp, etwas Orientierung in diesem zunehmend unübersichtlichen Feld zu bieten.
    Der Orthopäde 09/2011; DOI:10.1007/s00132-011-1748-z · 0.67 Impact Factor
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    ABSTRACT: When acquired or inborn bony defects cannot heal by the natural regeneration process due to being above the critical size or to particular diseases, e.g. osteoporosis, it becomes necessary to use bone substitute materials. These are materials which replace the missing bone tissue in host tissue and stimulate the bone healing process by mechanical and structural support either alone or in combination with other substances. This supporting effect can be attended by natural as well as artificial bone substitute materials and in a variety of ways. The biological efficiency of a bone substitute material is often classified with respect to the terms osteogenic, osteoconductive and osteoinductive stimulation. In reality however there is an overlap of several effective principles. Due to the limited availability of autologous bone and the disadvantages for the patient associated with the removal, intensive research is being carried out into artificial alternatives. The present article aims to offer some orientation in this confusing field by a systematic description of the various bone substitute materials.
    Der Orthopäde 03/2011; 40(9):761-73. · 0.51 Impact Factor
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    ABSTRACT: The communication of bone-forming osteoblasts and bone-resorbing osteoclasts is a fundamental requirement for balanced bone remodelling. For biomaterial research, development of in vitro models is necessary to investigate this communication. In the present study human bone marrow stromal cells and human monocytes were cultivated in order to differentiate into osteoblasts and osteoclasts, respectively. Finally, a cultivation regime was identified which firstly induces the differentiation of the human bone marrow stromal cells followed by the induction of osteoclastogenesis through the osteoblasts formed--without the external addition of the factors RANKL and M-CSF. As a feedback on osteoblasts enhanced gene expression of BSP II was detected for modifications which facilitated the formation of large multinuclear osteoclasts. Phenotype characterization was performed by biochemical methods (DNA, LDH, ALP, TRAP 5b), gene expression analysis (ALP, BSP II, RANKL, IL-6, VTNR, CTSK, TRAP, OSCAR, CALCR) as well as light microscopy, confocal laser scanning microscopy, and scanning electron microscopy. After establishing this model on polystyrene, similar positive results were obtained for cultivation on a relevant bone substitution material--a composite xerogel of silica, collagen, and calcium phosphate.
    European cells & materials 01/2011; 21:80-93. · 4.89 Impact Factor
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    ABSTRACT: The minerals involved in the formation of metazoan skeletons principally comprise glassy silica, calcium phosphate or carbonate. Because of their ancient heritage, glass sponges (Hexactinellida) may shed light on fundamental questions such as molecular evolution, the unique chemistry and formation of the first skeletal silica-based structures, and the origin of multicellular animals. We have studied anchoring spicules from the metre-long stalk of the glass rope sponge (Hyalonema sieboldi; Porifera, Class Hexactinellida), which are remarkable for their size, durability, flexibility and optical properties. Using slow-alkali etching of biosilica, we isolated the organic fraction, which was revealed to be dominated by a hydroxylated fibrillar collagen that contains an unusual [Gly-3Hyp-4Hyp] motif. We speculate that this motif is predisposed for silica precipitation, and provides a novel template for biosilicification in nature.
    Nature Chemistry 12/2010; 2(12):1084-8. DOI:10.1038/nchem.899 · 21.76 Impact Factor
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    ABSTRACT: Biological materials are a rewarding area of modern materials science, yielding both evolutionary insights and inspiration for biomimetic research. In particular, biocomposite structures are valuable sources of novel structures with unusual chemical properties, and they are very informative for the mechanisms of biomineralization. Here we describe a unique biocomposite of amorphous silica, crystalline aragonite, and chitin from species of the order Verongida, a group of marine sponges. The structures have been analyzed with a diverse suite of techniques, revealing a chitinous template for siliceous overgrowth containing aragonite-based crystal aggregates. Sponge chitin is an example of a specific template where two minerals in amorphous and crystalline forms are formed together with an organic molecule.
    Chemistry of Materials 08/2010; 22:1462-1471. DOI:10.1021/cm9026607 · 8.54 Impact Factor
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    ABSTRACT: Marine invertebrate organisms including sponges (Porifera) not only provide an abundant source of biologically active secondary metabolites but also inspire investigations to develop biomimetic composites, scaffolds and templates for practical use in materials science, biomedicine and tissue engineering. Here, we presented a detailed study of the structural and physico-chemical properties of three-dimensional skeletal scaffolds of the marine sponges Aiolochroia crassa, Aplysina aerophoba, A. cauliformis, A. cavernicola, and A. fulva (Verongida: Demospongiae). We show that these fibrous scaffolds have a multilayered design and are made of chitin. (13)C solid-state NMR spectroscopy, NEXAFS, and IR spectroscopy as well as chitinase digestion and test were applied in order to unequivocally prove the existence of alpha-chitin in all investigated species.
    International journal of biological macromolecules 08/2010; 47(2):132-40. DOI:10.1016/j.ijbiomac.2010.05.007 · 2.37 Impact Factor
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    ABSTRACT: In order to evaluate the biomedical potential of three-dimensional chitinous scaffolds of poriferan origin, chondrocyte culturing experiments were performed. It was shown for the first time that freshly isolated chondrocytes attached well to the chitin scaffold and synthesized an extracellular matrix similar to that found in other cartilage tissue engineering constructs. Chitin scaffolds also supported deposition of a proteoglycan-rich extracellular matrix of chondrocytes seeded bioconstructs in an in vivo environment. We suggest that chitin sponge scaffolds, apart from the demonstrated biomedical applications, are highly optimized structures for use as filtering systems, templates for biomineralization as well as metallization in order to produce catalysts.
    International journal of biological macromolecules 08/2010; 47(2):141-5. DOI:10.1016/j.ijbiomac.2010.05.009 · 2.37 Impact Factor

Publication Stats

2k Citations
274.88 Total Impact Points

Institutions

  • 2004–2014
    • Max Bergmann Center of Biomaterials (MBC)
      Dresden, Saxony, Germany
  • 1980–2013
    • Technische Universität Dresden
      • Institute of Materials Science
      Dresden, Saxony, Germany
  • 2008
    • Max Planck Institute of Biochemistry
      • Department of Membrane Biochemistry
      München, Bavaria, Germany
  • 1999
    • University of Leipzig
      • Institute of Experimental Physics
      Leipzig, Saxony, Germany