S Grässel

Publications (11)25.13 Total impact

• Article: The impact of chemical synovectomy with sodium morrhuate on human chondrocytes and cartilage in vitro.

  S Winkler, S Grässel, C Baier, S Anders, P Lechler, J Grifka, J Schaumburger
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  ABSTRACT: The vessel sclerosing property of sodium morrhuate is useful in treatment of recurrent joint effusions particularly in cases of knee joint effusions. It also can be employed as an addition to surgical synovectomy. Little is known about the effects of this drug on cartilage. This study was designed to investigate the cytotoxic impact of sodium morrhuate on human chondrocytes and cartilage tissue in vitro. Primary chondrocytes from 13 patients were isolated and cultivated in three-dimensional alginate cultures. Furthermore, femoral cartilage explants of 10 patients were cultivated in vitro. Both chondrocytes and cartilage explants were exposed to mixture of sodium morrhuate and mepivacaine in different concentrations simulating chemical synovectomy. After 48 h, cell proliferation, viability, and cytotoxicity were measured. The cartilage specimens were analyzed for apoptosis by immunohistochemistry. Up to a dilution of 1:600, cells were found to be 100 % viable with a proliferation rate of 74 % compared to controls. From 1:400 onwards, a significant increase in LDH release was measured which reached at dilution of 1:200 74 % of high control, whereas histological examination showed no proof of apoptosis or necrosis in cartilage tissue. The results of this in vitro study demonstrate that the cytotoxic effects of sodium morrhuate on human chondrocytes, which lack their original extracellular matrix, manifest between dilutions of 1:500 and 1:400 and increase with higher concentrations of the drug. This effect was not found for cartilage explants, though.
  Rheumatology International 09/2012; · 1.88 Impact Factor
• Article: [Cell-based therapy options for osteochondral defects. Autologous mesenchymal stem cells compared to autologous chondrocytes].

  S Grässel, S Anders
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  ABSTRACT: Cartilage defects are multifactorial and site-specific and therefore need a clear analysis of the underlying pathology as well as an individualized therapy so that cartilage repair lacks a one-for-all therapy. The results of comparative clinical studies using cultured chondrocytes in autologous chondrocyte implantation (ACI) have shown some superiority over conventional microfracturing under defined conditions, especially for medium or large defects and in long-term durability. Adult mesenchymal stem cells can be isolated from bone marrow, have the potency to proliferate in culture and are capable of differentiating into the chondrogenic pathway. They represent a promising versatile cell source for cartilage repair but the ideal conditions for cultivation and application in cartilage repair are not yet known or have not yet been characterized. Adding a scaffold offers mechanical stability and advances chondrogenic differentiation for both possible cell sources.
  Der Orthopäde 05/2012; 41(5):415-28; quiz 429-30. · 0.51 Impact Factor
• Article: A μCT analysis of the femoral bone stock in osteonecrosis of the femoral head compared to osteoarthrosis

  J. Beckmann, M. Matsuura, S. Grässel, F. Köck, J. Grifka, M. Tingart
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  ABSTRACT: IntroductionLong-term results of resurfacing in osteonecrosis of the femoral head (ONFH) are lacking and migration of the femoral component, necrosis of the femoral head and fracture of the femoral neck or head have been depicted. The aim of this study was to analyse the bone quality and 3-dimensional microarchitecture of the femoral head and neck in patients with ONFH compared to a group of patients with primary osteoarthritis (OA). Materials and methodsμCT was used to compare the microarchitecture of the femoral head and neck in patients with ONFH (n=10) and a control group of patients with primary OA (n=10). ResultsNo statistical significant differences were found for bone volume and the bone volume fraction, the connectivity density and the structure model index in patients with ONFH and those with OA (P>0.05). Patients with ONFH and those with OA had a similar trabecular number, thickness and separation (P>0.05). ConclusionBased on our findings, we might conclude that hip resurfacing arthroplasty is a possible therapeutic option in the treatment of ONFH of the young and active patient and that an insufficient bone stock in ONFH seems not to be the deciding factor for failure. However, we just focussed on one of probably various factors. Further studies are needed to support these findings.
  Archives of Orthopaedic and Trauma Surgery 04/2012; 129(4):501-505. · 1.37 Impact Factor
• Article: The transcription factor AP-2ɛ regulates CXCL1 during cartilage development and in osteoarthritis.

  A-K Wenke, S Niebler, S Grässel, A K Bosserhoff
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  ABSTRACT: Recently, the transcription factor AP-2ɛ was shown to be a regulator of hypertrophy in cartilage and to be differentially expressed in osteoarthritis (OA). However, the only known target gene of AP-2ɛ up to date is integrin alpha10. To better characterize the function of AP-2ɛ in cartilage we screened for additional target genes. Promoter analysis, ChIP-assays and electrophoretic mobility shift assay were used to characterize the regulation of a new AP-2ɛ target gene in detail. In this study, we determined the chemokine CXCL1, already known to be important in osteoarthritis (OA), as a new target gene of AP-2ɛ. We could confirm that CXCL1 is expressed in chondrocytes and significantly over-expressed in OA-chondrocytes. Transient transfection of chondrocytes with an AP-2ɛ expression construct led to a significant increase of the CXCL1 mRNA level in these cells. We identified three potential AP-2 binding sites within the CXCL1 promoter and performed luciferase assays, indicating that an AP-2 binding motif (AP-2.2) ranging from position -135 to -144 bp relative to the translation start is responsive to AP-2ɛ. This result was further addressed by site-directed mutagenesis demonstrating that activation of the CXCL1 promoter by AP-2ɛ is exclusively dependent on AP-2.2. Chromatin immunoprecipitation and electromobility shift assays confirmed the direct binding of AP-2ɛ to the CXCL1 promoter in OA-chondrocytes at this site. These findings revealed CXCL1 as a novel target gene of AP-2ɛ in chondrocytes and support the important role of AP-2ɛ in cartilage.
  Osteoarthritis and Cartilage 02/2011; 19(2):206-12. · 3.90 Impact Factor
• Article: Biomechanical forces exert anabolic effects on osteoblasts by activation of SMAD 1/5/8 through type 1 BMP receptor.

  B Rath, J Nam, J Deschner, J Schaumburger, M Tingart, S Grässel, J Grifka, S Agarwal
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  ABSTRACT: Osteoblasts are mechanosensitive cells, which respond to biomechanical stimuli to regulate the bone structure through anabolic and catabolic gene regulation. To examine the effects of mechanical forces on the osteogenic responses through the SMAD signaling in osteoblasts, the cells were cultured in well-characterized mechanoresponsive 3-D scaffolds and exposed to 10% dynamic compressive strain (Cmp) at 1 Hz. Subsequently, SMAD phosphorylation and osteogenic gene induction was examined. Osteoblasts cultured in 3-D scaffolds exhibited increased constitutive SMAD 1/5/8 phosphorylation, as compared to monolayers cultures. This SMAD 1/5/8 phosphorylation was further upregulated after 10, 30 and 60 min in response to Cmp, exhibiting a peak activation at 30 min. No significant changes in SMAD2 phosphorylation were observed, suggesting signals generated by Cmp may not activate the Transforming Growth Factor-β signaling cascade. Subsequently, biomechanical stimulation-induced SMAD 1/5/8 phosphorylation upregulated the expression of osteogenic genes such as Osteoprotegrin, Msx2 and Runx2. Dorsomorphin, a selective inhibitor of the bone morphogenetic protein (BMP) receptor type 1 (BMPR1), blocked Cmp-induced SMAD 1/5/8 phosphorylation, as well as Osteoprotegrin, Msx2 and Runx2 gene expression. Collectively, the present findings demonstrate that biomechanical stimulation of osteoblasts activates SMAD 1/5/8 in the BMP signaling pathway through BMPR1 and may enhance osteogenesis by upregulating SMAD-dependent osteogenic genes.
  Biorheology 01/2011; 48(1):37-48. · 1.93 Impact Factor
• Source

  Available from: PubMed Central

  Article: Enhanced cartilage regeneration in MIA/CD-RAP deficient mice.

  R Schmid, S Schiffner, A Opolka, S Grässel, T Schubert, M Moser, A-K Bosserhoff
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  ABSTRACT: Melanoma inhibitory activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP) is a small soluble protein secreted from chondrocytes. It was identified as the prototype of a family of extracellular proteins adopting an SH3 domain-like fold. In order to study the consequences of MIA/CD-RAP deficiency in detail we used mice with a targeted gene disruption of MIA/CD-RAP (MIA-/-) and analyzed cartilage organisation and differentiation in in vivo and in vitro models. Cartilage formation and regeneration was determined in models for osteoarthritis and fracture healing in vivo, in addition to in vitro studies using mesenchymal stem cells of MIA-/- mice. Interestingly, our data suggest enhanced chondrocytic regeneration in the MIA-/- mice, modulated by enhanced proliferation and delayed differentiation. Expression analysis of cartilage tissue derived from MIA-/- mice revealed strong downregulation of nuclear RNA-binding protein 54-kDa (p54(nrb)), a recently described modulator of Sox9 activity. In this study, we present p54(nrb) as a mediator of MIA/CD-RAP to promote chondrogenesis. Taken together, our data indicate that MIA/CD-RAP is required for differentiation in cartilage potentially by regulating signaling processes during differentiation.
  Cell Death & Disease 01/2010; 1:e97. · 5.33 Impact Factor
• Article: Synergistic effects of growth and differentiation factor-5 (GDF-5) and insulin on expanded chondrocytes in a 3-D environment.

  B Appel, J Baumer, D Eyrich, H Sarhan, S Toso, C Englert, D Skodacek, S Ratzinger, S Grässel, A Goepferich, T Blunk
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  ABSTRACT: To investigate the effects of growth and differentiation factor-5 (GDF-5) alone or in combination with insulin on engineered cartilage from primary or expanded chondrocytes during 3-dimensional in vitro culture. Juvenile bovine chondrocytes were seeded either as primary or as expanded (passage 2) cells onto polyglycolic acid fiber meshes and cultured for 3 weeks in vitro. Additionally, adult human chondrocytes were grown in pellet culture after expansion (passage 2). The culture medium was supplemented either with GDF-5 in varying concentrations or insulin alone, or with combinations thereof. For primary chondrocytes, the combination of GDF-5 and insulin led to increased proliferation and construct weight, as compared to either factor alone, however, the production of glycosaminoglycans (GAG) and collagen per cell were not affected. With expanded bovine chondrocytes, the use of GDF-5 or insulin alone led to only very small constructs with no type II collagen detectable. However, the combination of GDF-5 (0.01 or 0.1 microg/ml) and insulin (2.5 microg/ml) yielded cartilaginous constructs and, in contrast to the primary cells, the observed redifferentiating effects were elicited on the cellular level independent of proliferation (increased production of GAG and collagen per cell, clear shift in collagen subtype expression with type II collagen observed throughout the construct). The synergistic redifferentiating effects of the GDF-5/insulin combination were confirmed with expanded adult human cells, also exhibiting a clear shift in collagen subtype expression on the mRNA and protein level. In combination with insulin, GDF-5 appears to enable the redifferentiation of expanded chondrocytes and the concurrent generation of cartilaginous constructs. The demonstration of these synergistic effects also for adult human chondrocytes supports the clinical relevance of the findings.
  Osteoarthritis and Cartilage 06/2009; 17(11):1503-12. · 3.90 Impact Factor
• Article: Differential transcriptome analysis of intraarticular lesional vs intact cartilage reveals new candidate genes in osteoarthritis pathophysiology.

  M Geyer, S Grässel, R H Straub, G Schett, R Dinser, J Grifka, S Gay, E Neumann, U Müller-Ladner
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  ABSTRACT: To elucidate disease-specific molecular changes in osteoarthritis (OA) by analyzing the differential gene expression profile of damaged vs intact cartilage areas within the same joint of patients with OA of the knee using a combination of a novel RNA extraction technique and whole-genome oligonucleotide arrays. The transcriptome of macroscopically affected vs intact articular cartilage as determined by visual assessment was analyzed using an optimized mill-based total RNA isolation directly from the tissue and high density synthetic oligonucleotide arrays. Articular cartilage samples were obtained from patients with OA of the knee. Expression of differentially regulated genes was validated by real-time quantitative polymerase chain reaction and immunohistochemistry. The amount of RNA obtained by the optimized extraction procedure was at least 1 microg per 500 mg of cartilage and fulfilled the common quality requirements. After hybridization onto HG-U133 Plus 2.0 GeneChips (Affymetrix), 28.6-51.7% of the probe sets on the microarray showed a detectable signal above the signal threshold in the individual samples. A subset of 411 transcripts, which appeared to be differentially expressed, was obtained when applying predefined filtering criteria. Of these, six genes were found to be up-regulated in the affected cartilage of all patients, including insulin-like growth factor binding protein 3 (IGFBP-3), wnt-1-inducible signaling protein 1 (WISP-1), aquaporin 1 (AQP-1), delta/notch-like EGF-repeat containing transmembrane (DNER), decay accelerating factor (DAF), complement factor I (IF). The optimized methodical approach reported here not only allows to determine area-specific gene expression profiles of intraindividually different low-RNA containing OA cartilage specimens. In addition, this study also revealed novel genes not yet reported to play a role in the pathophysiology of joint destruction in OA.
  Osteoarthritis and Cartilage 10/2008; 17(3):328-35. · 3.90 Impact Factor
• Article: A muCT analysis of the femoral bone stock in osteonecrosis of the femoral head compared to osteoarthrosis.

  J Beckmann, M Matsuura, S Grässel, F Köck, J Grifka, M Tingart
  [show abstract] [hide abstract]
  ABSTRACT: Long-term results of resurfacing in osteonecrosis of the femoral head (ONFH) are lacking and migration of the femoral component, necrosis of the femoral head and fracture of the femoral neck or head have been depicted. The aim of this study was to analyse the bone quality and 3-dimensional microarchitecture of the femoral head and neck in patients with ONFH compared to a group of patients with primary osteoarthritis (OA). muCT was used to compare the microarchitecture of the femoral head and neck in patients with ONFH (n = 10) and a control group of patients with primary OA (n = 10). No statistical significant differences were found for bone volume and the bone volume fraction, the connectivity density and the structure model index in patients with ONFH and those with OA (P > 0.05). Patients with ONFH and those with OA had a similar trabecular number, thickness and separation (P > 0.05). Based on our findings, we might conclude that hip resurfacing arthroplasty is a possible therapeutic option in the treatment of ONFH of the young and active patient and that an insufficient bone stock in ONFH seems not to be the deciding factor for failure. However, we just focussed on one of probably various factors. Further studies are needed to support these findings.
  Archives of Orthopaedic and Trauma Surgery 06/2008; 129(4):501-5. · 1.37 Impact Factor
• Article: [Use of bone marrow mesenchymal stem cells for ex vivo cartilage regeneration].

  S Grässel, N Ahmed
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  ABSTRACT: Articular cartilage disorders and injuries often result in lifelong chronic pain and compromised quality of life. When it comes to local articular cartilage defects, modern medicine is limited to short-term pain relief and inflammation control. In extreme cases the affected tissue is surgically removed and replaced by a synthetic prosthesis of limited durability. Cell-based therapies to regenerate articular cartilage have been in use since 1994. Such therapies provide a healthy population of cells to the injured site and require differentiated chondrocytes from the uninjured site as base material. Their usage often leads to donor site morbidity and they generate rigid fibrous cartilage where more flexible hyaline cartilage is required. The major restrictive factors for such methods are inadequate number and limited proliferation capacity of chondrocytes in vitro. Tissue engineering of adult marrow stromal cells/mesenchymal stem cells (MSCs) with their almost unlimited proliferation potential and proven capability to differentiate into chondrocytes for ex vivo generation of cartilage tissue still remains a vision. For optimal harnessing of MSCs as chondroprogenitor cells, basic background information regarding commitment to the lineage, cartilage differentiation and the regulatory factors and molecules involved is essential.
  Der Orthopäde 04/2007; 36(3):227-35. · 0.51 Impact Factor
• Article: Einsatz von mesenchymalen Knochenmarkstammzellen für die Ex-vivo-Knorpelregeneration

  S. Grässel, N. Ahmed
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  ABSTRACT: Krankheiten und Verletzungen des artikulren Knorpels fhren hufig zu lebenslangen chronischen Schmerzzustnden. Bei fokalen Knorpeltraumata ist die moderne Medizin auf kurzzeitige Schmerzentlastung und Entzndungskontrolle begrenzt. In extremen Fllen wird das betroffene Gewebe operativ entfernt und durch synthetische Prothesen mit begrenzter Lebensdauer ersetzt. Seit 1994 werden zustzlich zellbasierte Therapien zur artikulren Knorpelregeneration eingesetzt. Diese therapeutischen Anstze stellen eine gesunde Zellpopulation fr den fokalen Defekt bereit und bentigen differenzierte Chondrozyten von einer unverletzten, wenig belasteten Stelle des Gelenks als Basismaterial. Deren Verwendung fhrt hufig zu Donormorbiditt, zustzlich produzieren diese Chondrozyten rigiden fibrsen Knorpel anstelle einer flexiblen hyalinen Knorpelmatrix. Der wichtigste restriktive Faktor hier ist die inadquate Zellzahl, sowie die limitierte Proliferationskapazitt differenzierter Chondrozyten in vitro.Das tissue engineering adulter stromaler Knochenmarkstammzellen bzw. mesenchymaler Stammzellen (MSZ) mit ihrem fast unbegrenzten Proliferationspotential und ihrer chondrogenen Differenzierungskapazitt zur Ex-vivo-Generierung von Knorpelgewebe ist noch eine Vision. Denn um MSZ als Chondroprogenitorzellen optimal zu nutzen, ist ein profundes Basiswissen bezglich ihrer Linienbestimmung, Knorpeldifferenzierungskapazitt und der involvierten regulatorischen Faktoren essentiell.Articular cartilage disorders and injuries often result in lifelong chronic pain and compromised quality of life. When it comes to local articular cartilage defects, modern medicine is limited to short-term pain relief and inflammation control. In extreme cases the affected tissue is surgically removed and replaced by a synthetic prosthesis of limited durability. Cell-based therapies to regenerate articular cartilage have been in use since 1994. Such therapies provide a healthy population of cells to the injured site and require differentiated chondrocytes from the uninjured site as base material. Their usage often leads to donor site morbidity and they generate rigid fibrous cartilage where more flexible hyaline cartilage is required. The major restrictive factors for such methods are inadequate number and limited proliferation capacity of chondrocytes in vitro.Tissue engineering of adult marrow stromal cells/mesenchymal stem cells (MSCs) with their almost unlimited proliferation potential and proven capability to differentiate into chondrocytes for ex vivo generation of cartilage tissue still remains a vision. For optimal harnessing of MSCs as chondroprogenitor cells, basic background information regarding commitment to the lineage, cartilage differentiation and the regulatory factors and molecules involved is essential.
  Der Orthopäde 02/2007; 36(3):227-235. · 0.51 Impact Factor