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Featured researches published by Solvig Lenz.


Folia Histochemica Et Cytobiologica | 2011

A preliminary study in osteoinduction by a nano-crystalline hydroxyapatite in the mini pig.

Werner GÜtz; Solvig Lenz; Christoph Reichert; Kai-Olaf Henkel; Volker Bienengrä ber; Laura Pernicka; Karsten K.H. Gundlach; Tomasz Gredes; Thomas Gerber; Tomasz Gedrange; Friedhelm Heinemann

To test the probable osteoinductive properties of NanoBone, a new highly non-sintered porous nano-crystalline hydroxylapatite bone substitute embedded into a silica gel matrix, granules were implanted subcutaneously and intramuscularly into the back region of 18 mini pigs. After periods of 5 and 10 weeks as well as 4 and 8 months, implantation sites were investigated using histological and histomorphometric procedures. Signs of early osteogenesis could already be detected after 5 weeks. The later periods were characterized by increasing membranous osteogenesis in and around the granules leading to the formation of bone-like structures showing periosteal and tendon-like structures with bone marrow and focal chondrogenesis. Bone formation was better in the subcutaneous than in the intramuscular implantation sites. This ectopic osteogenesis is discussed with regard to the nanoporosity and microporosity of the material, physico-chemical interactions at its surface, the differentiation of osteoblasts, the role of angiogenesis and the probable involvement of growth factors. The results of this preliminary study indicate that this biomaterial has osteoinductive potential and induces the formation of bone structures, mainly in subcutaneous adipose tissue in the pig.


International Journal of Nanomedicine | 2012

Osteogenic capacity of nanocrystalline bone cement in a weight-bearing defect at the ovine tibial metaphysis

Christoph Harms; Kai Helms; Tibor Taschner; Ioannis Stratos; Anita Ignatius; Thomas Gerber; Solvig Lenz; Stefan Rammelt; Brigitte Vollmar; Thomas Mittlmeier

The synthetic material Nanobone® (hydroxyapatite nanocrystallines embedded in a porous silica gel matrix) was examined in vivo using a standardized bone defect model in the ovine tibial metaphysis. A standardized 6 × 12 × 24-mm bone defect was created below the articular surface of the medial tibia condyles on both hind legs of 18 adult sheep. The defect on the right side was filled with Nanobone®, while the defect on the contralateral side was left empty. The tibial heads of six sheep were analyzed after 6, 12, and 26 weeks each. The histological and radiological analysis of the defect on the control side did not reveal any bone formation after the total of 26 weeks. In contrast, the microcomputed tomography analysis of the defect filled with Nanobone® showed a 55%, 72%, and 74% volume fraction of structures with bone density after 6, 12, and 26 weeks, respectively. Quantitative histomorphological analysis after 6, and 12 weeks revealed an osteoneogenesis of 22%, and 36%, respectively. Hematoxylin and eosin sections demonstrated multinucleated giant cells on the surface of the biomaterial and resorption lacunae, indicating osteoclastic resorptive activity. Nanobone® appears to be a highly potent bone substitute material with osteoconductive properties in a loaded large animal defect model, supporting the potential use of Nanobone® also in humans.


International Journal of Molecular Sciences | 2014

Evaluation of Osseointegration of Titanium Alloyed Implants Modified by Plasma Polymerization

Carolin Gabler; Carmen Zietz; Rebecca Göhler; Andreas Fritsche; Tobias Lindner; Maximilian Haenle; Birgit Finke; Jürgen Meichsner; Solvig Lenz; Bernhard Frerich; Frank Lüthen; J. Barbara Nebe; Rainer Bader

By means of plasma polymerization, positively charged, nanometre-thin coatings can be applied to implant surfaces. The aim of the present study was to quantify the adhesion of human bone cells in vitro and to evaluate the bone ongrowth in vivo, on titanium surfaces modified by plasma polymer coatings. Different implant surface configurations were examined: titanium alloy (Ti6Al4V) coated with plasma-polymerized allylamine (PPAAm) and plasma-polymerized ethylenediamine (PPEDA) versus uncoated. Shear stress on human osteoblast-like MG-63 cells was investigated in vitro using a spinning disc device. Furthermore, bone-to-implant contact (BIC) was evaluated in vivo. Custom-made conical titanium implants were inserted at the medial tibia of female Sprague-Dawley rats. After a follow-up of six weeks, the BIC was determined by means of histomorphometry. The quantification of cell adhesion showed a significantly higher shear stress for MG-63 cells on PPAAm and PPEDA compared to uncoated Ti6Al4V. Uncoated titanium alloyed implants showed the lowest BIC (40.4%). Implants with PPAAm coating revealed a clear but not significant increase of the BIC (58.5%) and implants with PPEDA a significantly increased BIC (63.7%). In conclusion, plasma polymer coatings demonstrate enhanced cell adhesion and bone ongrowth compared to uncoated titanium surfaces.


Journal of Biomedical Materials Research Part B | 2009

Early matrix change of a nanostructured bone grafting substitute in the rat.

Weiguo Xu; Gerd Holzhüter; Heiko Sorg; Daniel Wolter; Solvig Lenz; Thomas Gerber; Brigitte Vollmar

A nanocrystalline bone substitute embedded in a highly porous silica gel matrix (NanoBone) has previously been shown to bridge bone defects by an organic matrix. As the initial host response on the bone graft substitute might be a determinant for subsequent bone formation, our present purpose was to characterize the early tissue reaction on this biomaterial. After implantation of 80 mg of NanoBone into the adipose neck tissue of a total of 35 rats, grafts were harvested for subsequent analysis at days 3, 6, 9, 12, and 21. The biomaterial was found encapsulated by granulation tissue which partly penetrated the implant at day 3 and completely pervaded the graft at day 12 on implantation. Histology revealed tartrate-resistant acid phosphatase (TRAP)-positive giant cells covering the biomaterial. ED1 (CD68) immunopositivity of these cells further indicated their osteoclast-like phenotype. Scanning electron microscopy revealed organic tissue components within the periphery of the graft already at day 9, whereas the central hematoma region still presented the silica-surface of the biomaterial. Energy dispersive X-ray spectroscopy further demonstrated that the silica gel was degraded faster in the peripheral granulation tissue than in the central hematoma and was replaced by organic host components by day 12. In conclusion, the silica gel matrix is rapidly replaced by carbohydrate macromolecules. This might represent a key step in the process of graft degradation on its way toward induction of bone formation. The unique composition and structure of this nanoscaled biomaterial seem to support its degradation by host osteoclast-like giant cells.


Macromolecular Rapid Communications | 2010

Ring‐Opening Metathesis Polymerization‐Based Synthesis of CaCO3 Nanoparticle‐Reinforced Polymeric Monoliths for Tissue Engineering

Franziska Weichelt; Bernhard Frerich; Solvig Lenz; Stefanie Tiede; Michael R. Buchmeiser

Porous monolithic materials have been prepared via ring-opening metathesis polymerization from norborn-2-ene and a 7-oxanorborn-2-ene-based cross-linker in the presence of porogenic solvents (i.e., 2-propanol and toluene) and norborn-2-enephosphonate surface-modified CaCO(3) nanoparticles, using the 3(rd) -generation Grubbs-initiator RuCl(2) (Py)(2) (IMesH(2) )(CHPh). The experimental setup and the conditions chosen allowed for the manufacturing of polymeric monoliths characterized by a homogeneous distribution of the inorganic nanoparticles throughout the polymeric monolith. Depending on the nanoparticle content, the macropore diameters could be varied in the 30-120 µm regime. Noteworthy, the addition of nanoparticles did not affect the phase separation-triggered formation of the monolithic matrix nor the meso- and microporosity as evidenced by N(2) -adsorption experiments.


Beilstein Journal of Organic Chemistry | 2010

ROMP-Derived cyclooctene-based monolithic polymeric materials reinforced with inorganic nanoparticles for applications in tissue engineering

Franziska Weichelt; Solvig Lenz; Stefanie Tiede; Ingrid Reinhardt; Bernhard Frerich; Michael R. Buchmeiser

Summary Porous monolithic inorganic/polymeric hybrid materials have been prepared via ring-opening metathesis copolymerization starting from a highly polar monomer, i.e., cis-5-cyclooctene-trans-1,2-diol and a 7-oxanorborn-2-ene-derived cross-linker in the presence of porogenic solvents and two types of inorganic nanoparticles (i.e., CaCO3 and calcium hydroxyapatite, respectively) using the third-generation Grubbs initiator RuCl2(Py)2(IMesH2)(CHPh). The physico-chemical properties of the monolithic materials, such as pore size distribution and microhardness were studied with regard to the nanoparticle type and content. Moreover, the reinforced monoliths were tested for the possible use as scaffold materials in tissue engineering, by carrying out cell cultivation experiments with human adipose tissue-derived stromal cells.


Key Engineering Materials | 2005

Comparison of a New Kind of Calcium Phosphate Formula Versus Conventional Calciumphosphate Matrices in Treating Bone Defects – A Long-Term Investigation in Pigs

Kai-Olaf Henkel; V. Bienengräber; Solvig Lenz; Th. Gerber

In clinical practice arises an increasing need for bone substitute materials. The main inorganic part of bone is the hydroxyapatite (HA). A new hydroxyapatite formula was created by a sol-gel-process at low temperature level [4]. The aim of this investigation was to test the biodegradation and the induction of bone formation by this new material and to compare these versus conventional fabricated HA and ß-TCP. 30 one-year-old Goettingen minipigs were divided into five groups. Critical size defect (>5 m3) in the mandible was treated differently in all 5 groups:-group I- filling with pure HA, which was fabricated by sol-gel-technique, group II- control, only gelatinous material was given, group III- conventional ß-TCP [Cerasorb®], in group IV- conventional HA [Endobone®] and in group V [Targobone®], a non denatureted bovine collagen matrix was used. Macroscopical and microscopical investigations of the former defects were made eight months postoperatively. The bone formation was superior in the sol-gel-HA-group (group I) in comparison with the control groups (group II) and the conventional fabricated ceramics groups (III and IV). In the sol-gel-HA group, the biodegradation of this new biomaterial was considered to very good with a resorption rate of more than 98%; eight months postoperatively. In this group complete bone formation was seen in former defects. In the control group, only an incomplete bone formation with 48.4% of the defect area was noted. This difference was significant (p<0,001). A less bone formation was also observed in group III and IV with 57.6% and 56.9%. The bovine non-denaturated collagen matrix (group V) leads to only 20% of new formed bone. The new calcium phosphate formula made by a sol-gel method seems to be superior and suitable for filling bone defects.


Journal of Biomedical Materials Research Part B | 2011

Lateral augmentation of the mandible in minipigs with a synthetic nanostructured hydroxyapatite block

Mark Kirchhoff; Solvig Lenz; Kai-Olaf Henkel; Bernhard Frerich; Gerd Holzhüter; Sven Radefeldt; Thomas Gerber

The purpose of this study was to evaluate biomaterial degradation and new bone formation after implantation of a nanostructured hydroxyapatite (HA) grafting block. Furthermore, physical characteristics of the biomaterial were measured. The biomaterial consists of nanostructured HA embedded in a porous matrix of silica (SiO(2) ) gel. The blocks with two different contents of silica (group A: 24 wt % and group B: 39 wt %) were fixed with titanium screws at the lateral aspect of the mandible of minipigs (n = 5). The specific surface areas of both blocks were measured using Brunauer-Emmett-Teller (BET) equation and mercury intrusion. In all animals, the wound healing was uneventful. After 5 weeks, the biomaterial percentage was 51.5% ± 12.1% for group A and 33.2% ± 5.9% for group B (p = 0.017). New bone formation accounted to 7.6% ± 6.0% for group A and 15.3% ± 8.3% for group B (p = 0.126) after 5 weeks. After 10 weeks, further resorption of the biomaterial led to percentages of 30.6% ± 10.0% for group A and 12.1% ± 6.7% for group B (p = 0.000). After 10 weeks, new bone formations were measured to be 34.1% ± 10.8% in group A and 39.9% ± 13.5% in group B (p = 0.383). The rate of degradation of the biomaterial is controlled by the composition of the material. A higher content of silica gel matrix leads to faster degradation of the biomaterial. The formation of new bone failed to show a significant difference between both groups.


Key Engineering Materials | 2011

Nanostructured Bone Grafting Substitutes – A Pathway to Osteoinductivity

Thomas Gerber; Solvig Lenz; Gerd Holzhüter; Werner Götz; Kai Helms; Christoph Harms; Th. Mittlmeier

The comparative investigation of a highly nanoporous bone grafting material (NanoBone S, NBS) and a sintered hydroxyapatite ceramic (Cerabone, CB) aimed to show the influence of the structure of the material on osteoinductivity.NBS consists of synthetic nanocrystalline hydroxyapatite embedded in a porous silica gel matrix. Its specific surface amounts 206 m2/g in contrast to CB with a specific surface of 0.4 m2/g.The biomaterials were implanted in the neck region of 18 sheep and left there for the periods of 6, 12 and 26 weeks. In each case granulate was implanted superficially into the trapezius muscle and into the subcutaneous adipose tissue respectively. The samples were analysed by micro-CT, histochemistry, immunohistochemistry and histomorphometry. In the case of NBS ossicles had developed. An intensive remodelling process was verifiable. The bone formation in CB was marginal.As a basic phenomenon in NBS, the substitution of the original SiO2 gel matrix by organic molecules forming an organic matrix around the embedded hydroxyapatite seams to be the key event causing these results.


Key Engineering Materials | 2012

Bone Grafting Putty – Animal Experiments and Clinical Applications

Thomas Gerber; Cornelia Ganz; Weiguo Xu; F. Maier; Bernhard Frerich; Solvig Lenz

The aim of the described study was to generate and evaluate a putty-like bone graft substitute ready to use for dental and orthopedic surgery. According to the asking of clinicians the new material should avoid the necessity of mixing blood and bone graft during the surgical process. Therefor the granulous material NanoBone® has been combined with a hydrogel based on Polyvinylpyrrolidone (PVP) and tested in standardized rat tibia defect over a period of 12 weeks and evaluated histologically. The results showed no limitations of the granulate characteristics in matrix change and hence a high level of vascularization and bone formation. An example for dental application shows the outcome in the case of socket preservation.

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Kai Helms

University of Rostock

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