Chantal Pauli

Gulhane Military Medical Academy, Ankara, Ankara, Turkey

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Publications (16)62.74 Total impact

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    ABSTRACT: Many studies in the field of cell-based cartilage repair have focused on identifying markers associated with the differentiation status of human articular chondrocytes (HAC) that could predict their chondrogenic potency. A previous study from our group showed a correlation between the expression of S100 protein in HAC and their chondrogenic potential. The aims of the current study were to clarify which S100 proteins are associated with HAC differentiation status and to provide an S100-based assay for measuring HAC chondrogenic potential. The expression patterns of S100A1 and S100B were investigated in cartilage and in HAC cultured under conditions promoting dedifferentiation (monolayer culture) or redifferentiation (pellet culture or BMP4 treatment in monolayer culture), using characterized antibodies specifically recognizing S100A1 and S100B, by immunohistochemistry, immunocytochemistry, Western blot, and gene expression analysis. S100A1 and S100B were expressed homogeneously in all cartilage zones, and decreased during dedifferentiation. S100A1, but not S100B, was re-expressed in pellets and co-localized with collagen II. Gene expression analysis revealed concomitant modulation of S100A1, S100B, collagen type II, and aggrecan: down-regulation during monolayer culture and up-regulation upon BMP4 treatment. These results strongly support an association of S100A1, and to a lesser extent S100B, with the HAC differentiated phenotype. To facilitate their potential application, we established an S100A1/B-based flow cytometry assay for accurate assessment of HAC differentiation status. We propose S100A1 and S100B expression as a marker to develop potency assays for cartilage regeneration cell therapies, and as a redifferentiation readout in monolayer cultures aiming to investigate stimuli for chondrogenic induction. J. Cell. Physiol. © 2014 Wiley Periodicals, Inc.
    Journal of Cellular Physiology 01/2014; · 4.22 Impact Factor
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    ABSTRACT: OBJECTIVE.: Identify novel genes and pathways specific to superficial (SZ), middle (MZ) and deep zones (DZ) of normal articular cartilage. METHODS.: Articular cartilage was obtained from knees of 4 normal human donors. The cartilage zones were dissected on a microtome. RNA was analyzed on human genome arrays. Data obtained with human tissue were compared to bovine cartilage zone specific DNA arrays. Genes differentially expressed between zones were evaluated using direct annotation for structural or functional features, and by enrichment analysis for integrated pathways or functions. RESULTS.: The greatest differences were observed between SZ and DZ in both human and bovine cartilage. The MZ was transitional between the SZ and DZ and thereby shared some of the same pathways as well as structural/functional features of the adjacent zones. Cellular functions and biological processes enriched in the SZ relative to the DZ, include most prominently ECM receptor interactions, cell adhesion molecules, regulation of actin cytoskeleton, ribosome-related functions and signaling aspects such as Interferon gamma, IL4, CDC42Rac and Jak-Stat. Two pathways were enriched in the DZ relative to the SZ, including PPARG and EGFR/SMRTE. CONCLUSION.: These differences in cartilage zonal gene expression identify new markers and pathways that govern the unique differentiation status of chondrocyte subpopulations. © 2012 American College of Rheumatology.
    Arthritis & Rheumatology 11/2012; · 7.48 Impact Factor
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    ABSTRACT: To correlate short and long T2* water fractions, derived from ultrashort-echo time (TE) magnetic resonance (MR) imaging, with semiquantitative histopathologic and polarized light microscopic (PLM) assessment of human cadaveric patellae cartilage. Twenty human cadaveric patellae were evaluated by using ultrashort-TE imaging, spin-echo imaging, histopathologic analysis, and PLM, with institutional review board approval. Short and long T2* water components were evaluated for each patella by using bicomponent fitting of ultrashort-TE signal decay. Four to six regions of interest (ROIs) within each patella were chosen for correlation between ultrashort-TE bicomponent analysis, histopathologic grading (Mankin score), and PLM grading (Vaudey score). Ultrashort-TE imaging with bicomponent analysis showed two distinct water components with a short T2* and a longer T2* in all patellae. ROI analysis showed that the short T2* fraction was correlated significantly with the Mankin (ρ = 0.66, P < .001) and Vaudey (ρ = 0.68, P < .001) scores. The Mankin scores were weakly positively correlated with T2 (ρ = 0.28, P = .13) and short T2* (ρ = 0.24, P = .14) but were negatively correlated with long T2* (ρ = -0.55, P < .01). The Vaudey scores were weakly positively correlated with T2 (ρ = 0.18, P = .16) and short T2* (ρ = 0.22, P = .14) but were negatively correlated with long T2* (ρ = -0.55, P < .01). Short T2* water fraction derived from ultrashort-TE imaging with bicomponent analysis correlates significantly with both the Mankin and Vaudey scores and may serve as a biomarker of cartilage degeneration.
    Radiology 05/2012; 264(2):484-93. · 6.34 Impact Factor
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    ABSTRACT: Dynamic loading and perfusion culture environments alone are known to enhance cartilage extracellular matrix (ECM) production in dedifferentiated articular chondrocytes. In this study, we explored whether a combination of these factors would enhance these processes over a free-swelling (FS) condition using adult human articular chondrocytes embedded in 2% alginate. The alginate constructs were placed into a bioreactor for perfusion (P) only (100 μL/per minute) or perfusion and dynamic compressive loading (PL) culture (20% for 1 h, at 0.5 Hz), each day. Control FS alginate gels were maintained in six-well static culture. Gene expression analysis was conducted on days 7 and 14, while cell viability, immunostaining, and mechanical property testing were performed on day 14 only. Total glycosaminoglycan (GAG) content and GAG synthesis were assessed after 14 days. Col2a1 mRNA expression levels were significantly higher (at least threefold; p<0.05) in both bioreactor conditions compared with FS by days 7 and 14. For all gene studies, no significant differences were seen between P and PL treatments. Aggrecan mRNA levels were not significantly altered in any condition although both GAG/DNA and (35)S GAG incorporation studies indicated higher GAG retention and synthesis in the FS treatment. Collagen type II protein deposition was low in all samples, link protein distribution was more diffuse in FS condition, and aggrecan deposition was located in the outer regions of the alginate constructs in both bioreactor conditions, yet more uniformly in the FS condition. Catabolic gene expression (matrix metalloproteinase 3 [MMP3] and inducible nitric oxide synthase [iNOS]) was higher in bioreactor conditions compared with FS, although iNOS expression levels decreased to approximately fourfold less than the FS condition by day 14. Our data indicate that conditions created in the bioreactor enhanced both anabolic and catabolic responses, similar to other loading studies. Perfusion was sufficient alone to promote this dual response. PL increased the deposition of aggrecan surrounding cells compared with the other conditions; however, overall low GAG retention in the bioreactor system was likely due to both perfusion and catabolic conditions created. Optimal conditions, which permit appropriate anabolic and catabolic processes for accumulation of ECM and tissue remodeling for neocartilage development, specifically for humans, are needed.
    Tissue Engineering Part A 04/2012; 18(17-18):1784-92. · 4.64 Impact Factor
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    ABSTRACT: The development and patterns of spontaneous age-related changes in the anterior cruciate ligament (ACL) and their relationship to articular cartilage degeneration are not well characterized. This study was undertaken to investigate the types and temporal sequence of age-related ACL changes and to determine their correlation with cartilage lesion patterns at all stages of osteoarthritis (OA) development in human knee joints without prior joint trauma. Human knee joints (n = 120 from 65 donors ages 23-92) were obtained at autopsy, and ACLs and cartilage were graded macroscopically and histologically. Inflammation surrounding the ACL was assessed separately. Histologic ACL substance scores and ligament sheath inflammation scores increased with age. Collagen fiber disorganization was the earliest and most prevalent change. The severity of mucoid degeneration and chondroid metaplasia in the ACL increased with the development of cartilage lesions. A correlation between ACL degeneration and cartilage degeneration was observed, especially in the medial compartment of the knee joint. Our findings indicate that ACL degeneration is highly prevalent in knees with cartilage defects and may even precede cartilage changes. Hence, ACL deficiencies may not only be important in posttraumatic OA, but may also be a feature associated with knee OA pathogenesis in general.
    Arthritis & Rheumatology 03/2012; 64(3):696-704. · 7.48 Impact Factor
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    ABSTRACT: To compare the MANKIN and OARSI cartilage histopathology assessment systems using human articular cartilage from a large number of donors across the adult age spectrum representing all levels of cartilage degradation. Human knees (n=125 from 65 donors; age range 23-92) were obtained from tissue banks. All cartilage surfaces were macroscopically graded. Osteochondral slabs representing the entire central regions of both femoral condyles, tibial plateaus, and the patella were processed for histology and Safranin O - Fast Green staining. Slides representing normal, aged, and osteoarthritis (OA) tissue were scanned and electronic images were scored online by five observers. Statistical analysis was performed for inter- and intra-observer variability, reproducibility and reliability. The inter-observer variability among five observers for the MANKIN system showed a similar good Intra-class correlation coefficient (ICC>0.81) as for the OARSI system (ICC>0.78). Repeat scoring by three of the five readers showed very good agreement (ICC>0.94). Both systems showed a high reproducibility among four of the five readers as indicated by the Spearman's rho value. For the MANKIN system, the surface represented by lesion depth was the parameter where all readers showed an excellent agreement. Other parameters such as cellularity, Safranin O staining intensity and tidemark had greater inter-reader disagreement. Both scoring systems were reliable but appeared too complex and time consuming for assessment of lesion severity, the major parameter determined in standardized scoring systems. To rapidly and reproducibly assess severity of cartilage degradation, we propose to develop a simplified system for lesion volume.
    Osteoarthritis and Cartilage 02/2012; 20(6):476-85. · 4.26 Impact Factor
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    ABSTRACT: Manipulation of cell patterns in three dimensions in a manner that mimics natural tissue organization and function is critical for cell biological studies and likely essential for successfully regenerating tissues--especially cells with high physiological demands, such as those of the heart, liver, lungs, and articular cartilage.(1, 2) In the present study, we report on the feasibility of arranging iron oxide-labeled cells in three-dimensional hydrogels using magnetic fields. By manipulating the strength, shape, and orientation of the magnetic field and using crosslinking gradients in hydrogels, multi-directional cell arrangements can be produced in vitro and even directly in situ. We show that these ferromagnetic particles are nontoxic between 0.1 and 10 mg/mL; certain species of particles can permit or even enhance tissue formation, and these particles can be tracked using magnetic resonance imaging. Taken together, this approach can be adapted for studying basic biological processes in vitro, for general tissue engineering approaches, and for producing organized repair tissues directly in situ.
    Tissue Engineering Part C Methods 02/2012; 18(7):496-506. · 4.64 Impact Factor
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    ABSTRACT: PURPOSE Determine if quantitative conventional and Ultrashort Time-to-Echo (UTE) MR imaging is sensitive to meniscus degeneration, in an in vitro model using enzymatic collagen degradation. METHOD AND MATERIALS Cadaveric knees (n=3, 1F, 80±6.1 yrs) were sectioned sagittally to obtain ~mid-medial 5-mm slices. Triangular meniscus samples were taken, and submerged in saline (n=1) or collagenase (n=3) solution for 0, 4, 8 or 12 hrs. At each time point, samples were imaged using conventional multi-echo T2 (TR=2000 ms, TE=10-90 ms) and novel UTE T2* (TR=300 ms, TE=0.012 to 20 ms) techniques. MR properties were normalized to values at time 0 to determine percent increase in value with time. Bathing solutions were collected and analyzed for collagen content using Sircol assay. RESULTS Collagenase treatment resulted in increasing loss of collagen with time (Fig.A). SE T2 and UTE T2* values of the meniscus samples were 14~21 ms and 3~16 ms, respectively, prior to the collagenase treatment. After 12 hr of treatment, SE T2 values increased ~60% (Fig.B) to 22~32 ms, while UTE T2* values increased ~400% (Fig.C) to 17~20 ms. In contrast, the saline-treated control did not show marked changes in the values. CONCLUSION These results suggest a higher sensitivity of quantitative UTE technique, relative to conventional technique, to a loss of collagen in human menisci. CLINICAL RELEVANCE/APPLICATION Higher sensitivity of UTE MRI is useful for early and quantitative evaluation of meniscal degeneration and injury that can lead to osteoarthritis, as well as follow up after therapeutic interventions.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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    ABSTRACT: PURPOSE The purpose of this study was to investigate the free and bound water components in human cadaveric meniscus using ultrashort TE (UTE) imaging and bi-component analysis. METHOD AND MATERIALS A two-dimensional (2D) UTE imaging sequence was implemented on a 3T Signa TwinSpeed scanner (GE Healthcare Technologies, Milwaukee, WI). The 2D UTE sequence employed half-pulse radiofrequency (RF) excitation, radial ramp sampling and fast transmit/receive switching to reduce nominal TE to 8 μs. 12 fresh lateral and medial menisci were collected one to two days after death. Each meniscus was placed in a plastic container filled with perfluorooctyl bromide (PFOB) solution to minimize susceptibility effects at tissue air interface. The following UTE imaging parameters were used: TR=200 ms, FOV = 6-8 cm, matrix=512x512, flip angle = 45°, BW = 62.5 kHz, slice = 1.7 mm, 16 TEs ranged from 8 μs to 40 ms. In-house developed bi-component fitting software was used to calculate T2* and the fractions of the bound and free water components in each meniscus. RESULTS Excellent fitting was generated in each case with residual signal less than 3%. As shown in Figure 1, there was a significant increase in bound water T2*, from 1.54 ± 0.14 ms for a normal meniscus to 10.56 ± 1.42 ms for a torn meniscus (586% increase). The free water T2* increased from 13.57 ± 0.83 ms for the normal meniscus to 56.45 ± 4.83 ms for the torn meniscus. Nearly half the meniscus water is bound to the collagen matrix. CONCLUSION This result indicates the shorter T2* component, or water bound to the meniscal collagen matrix is sensitive to degeneration. The quantitative information on free and bound water T2* and their fractions may be used as bio-markers for early degeneration of the meniscus and other joint tissues. CLINICAL RELEVANCE/APPLICATION UTE imaging combined with bi-component analysis allows quantitative evaluation of both the free and bound water in the meniscus. The bound component may be more sensitive to degeneration.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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    ABSTRACT: PURPOSE In this study an ultrashort TE (UTE) pulse sequence was used with bi-component analysis to quantify both the short (water bound to collagen and proteoglycan) and long T2 (free water) components in articular cartilage and the meniscus of the knee joint in vivo. METHOD AND MATERIALS A two-dimensional (2D) multi-echo UTE imaging sequence with a minimal TE of 8 μs was implemented on a 3T Signa TwinSpeed scanner (GE Healthcare Technologies, Milwaukee, WI). Four-echo UTE acquisitions were performed with four sets of TEs: (0.008, 4.4, 20, 40 ms); (0.4, 6.6, 25, 50 ms); (0.8, 11, 30, 60 ms); and (2.2, 16, 35, 70 ms), which covered both the short T2 (T2* < 3 ms) and long T2 (T2* > 20 ms) range. Other imaging parameters include: FOV = 14 cm, 2 mm slice thickness, TR = 200 ms, 320 readout, 455 projections, 512×512 reconstruction matrix size, bandwidth = 125 kHz, flip angle = 45º, scan time = 3 min. The total quantification time was 3×4 = 12 minutes. In-house developed bi-component fitting software was used to calculate T2* and fractions of the bound and free water components. Five healthy volunteers were recruited. RESULTS High quality UTE images were achieved in all five volunteers without noticeable motion or streak artifact. Excellent bi-component fitting was achieved for femoral and tibial cartilage as well as meniscus. Figure 1A-H shows selected multi-echo UTE images, as well as bi-component analysis at regions of interest drawn in articular cartilage and meniscus with excellent curve-fitting. The bi-component analysis shows predominantly long T2 nature of articular cartilage, which comprises 18% short T2* component (T2*~0.5 ms) and 82% long T2* component (T2*~39 ms), and predominantly short T2 nature of the meniscus, which comprises 47% short T2* component (T2*~2.4 ms) and 53% long T2* component (T2*~24 ms). CONCLUSION Free and bound water quantification of the articular cartilage and meniscus is feasible in vivo by using repeated multi-echo UTE acquisitions with varied TE delays to cover both the short and long T2 ranges. Bi-component analysis provides fast and reliable quantification of the short and long T2* values and the corresponding fractions of each component. CLINICAL RELEVANCE/APPLICATION UTE bi-component analysis provides robust evaluation of the short T2* component, which may be important for early evaluation of osteoarthritis.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
  • Osteoarthritis and Cartilage 09/2011; 19. · 4.26 Impact Factor
  • Osteoarthritis and Cartilage 09/2011; · 4.26 Impact Factor
  • Osteoarthritis and Cartilage 09/2011; 19. · 4.26 Impact Factor
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    ABSTRACT: Meniscus lesions following trauma or associated with osteoarthritis (OA) have been described, yet meniscus aging has not been systematically analyzed. The objectives of this study were to (1) establish standardized protocols for representative macroscopic and microscopic analysis, (2) improve existing scoring systems, and (3) apply these techniques to a large number of human menisci. Medial and lateral menisci from 107 human knees were obtained and cut in two different planes (triangle/cross section and transverse/horizontal section as well) in three separate locations (middle portion, anterior and posterior horns). All sections included vascular and avascular regions and were graded for (1) surface integrity, (2) cellularity, (3) matrix/fiber organization and collagen alignment, and (4) Safranin-O staining intensity. The cartilage in all knee compartments was also scored. The new macroscopic and microscopic grading systems showed high inter-reader and intra-reader intraclass correlation coefficients. The major age-related changes in menisci in joints with no or minimal OA included increased Safranin-O staining intensity, decreased cell density, the appearance of acellular zones, and evidence of mucoid degeneration with some loss of collagen fiber organization. The earliest meniscus changes occurred predominantly along the inner rim. Menisci from OA joints showed severe fibrocartilaginous separation of the matrix, extensive fraying, tears and calcification. Abnormal cell arrangements included decreased cellularity, diffuse hypercellularity along with cellular hypertrophy and abnormal cell clusters. In general, the anterior horns of both medial and lateral menisci were less affected by age and OA. New standardized protocols and new validated grading systems allowed us to conduct a more systematic evaluation of changes in aging and OA menisci at a macroscopic and microscopic level. Several meniscus abnormalities appear to be specific to aging in the absence of significant OA. With aging the meniscal surface can be intact but abnormal matrix organization and cellularity were observed within the meniscal substance. The increased Safranin-O staining appears to represent a shift from fibroblastic to chondrocytic phenotype during aging and early degeneration.
    Osteoarthritis and Cartilage 06/2011; 19(9):1132-41. · 4.26 Impact Factor
  • Osteoarthritis and Cartilage 01/2011; 19. · 4.26 Impact Factor
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    ABSTRACT: To use the ultrashort time-to-echo magnetic resonance imaging (UTE MRI) technique to quantify short T2* properties (obtained through gradient echo) of a disc from the human temporomandibular joint (TMJ) and to corroborate regional T2* values with biomechanical properties and histologic appearance of the discal tissues. A cadaveric human TMJ was sliced sagittally and imaged by conventional and UTE MRI techniques. The slices were then subjected to either biomechanical indentation testing or histologic evaluation, and linear regression was used for comparison to T2* maps obtained from UTE MRI data. Feasibility of in vivo UTE MRI was assessed in two human volunteers. The UTE MRI technique of the specimens provided images of the TMJ disc with greater signal-to-noise ratio (~3 fold) and contrast against surrounding tissues than conventional techniques. Higher T2* values correlated with lower indentation stiffness (softer) and less collagen organization as indicated by polarized light microscopy. T2* values were also obtained from the volunteers. UTE MRI facilitates quantitative characterization of TMJ discs, which may reflect structural and functional properties related to TMJ dysfunction.
    Journal of orofacial pain 01/2011; 25(4):345-53. · 2.39 Impact Factor

Publication Stats

84 Citations
62.74 Total Impact Points

Institutions

  • 2011
    • Gulhane Military Medical Academy
      • Department of Radiology
      Ankara, Ankara, Turkey
    • The Scripps Research Institute
      • Department of Molecular and Experimental Medicine
      La Jolla, CA, United States