Bio-Medical Materials and Engineering - Volume 20, issue 6

Authors: Kambe, Yusuke | Takeda, Yuji | Yamamoto, Koji | Kojima, Katsura | Tamada, Yasushi | Tomita, Naohide

Article Type: Research Article

Abstract: Initial chondrocyte-material interactions are important for cell behaviors such as proliferation, phenotypic expression and matrix synthesis. Previously, we showed that chondrocytes cultured in/on silk fibroin scaffolds proliferate without dedifferentiating into fibroblast-like cells and that RGDS sequences genetically interfused in the fibroin light chain protein enhance cartilage tissue formation. In the present study, the adhesive force of chondrocytes was measured on fibroin substrates containing RGDS-expressing fibroin molecules produced by transgenic silkworms at the different densities of 0, 0.6, 1.5 and 3.0 mol%. The degree of chondrocyte attachment to fibroin substrates increased with the number of RGDS-expressing fibroin molecules. Moreover, the adhesive …force per unit spreading area of a single cultured chondrocyte exhibited a peak that was higher with increased RGDS concentrations. The results of this study indicate that the RGDS sequences genetically interfused in the fibroin light chain protein exert effects on chondrocytes' adhesive behavior and can enhance cartilage tissue organization. Show more

Keywords: Adhesive force, cartilage regeneration, concentration dependence, RGD peptide, transgenic silkworms

DOI: 10.3233/BME-2010-0644

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 309-316, 2010

Authors: Mueller-Rath, Ralf | Gavénis, Karsten | Andereya, Stefan | Mumme, Torsten | Albrand, Monique | Stoffel, Marcus | Weichert, Dieter | Schneider, Ulrich

Article Type: Research Article

Abstract: Three-dimensional autologous chondrocyte implantation based on collagen gel as matrix scaffold has become a clinically applied treatment for focal defects of articular cartilage. However, the low biomechanical properties of collagen gel makes intraoperative handling difficult and creates the risk of early damages to the vulnerable implant. The aim of the study was to create a stabilized form of collagen gel and to evaluate its biomechanical and biochemical properties. Collagen type-I gel was seeded with human articular chondrocytes. 20 samples were subject to condensation which was achieved mechanically by compression and filtration. Control samples were left uncondensed. From both types …of gels 10 samples were used for initial biomechanical evaluation by means of unconfined compression and 10 samples were cultivated under standard conditions in vitro. Following cultivation the samples were evaluated by conventional histology and immunohistochemistry. The proliferation rate was calculated and matrix gene expression was quantified by real-time PCR. The biomechanical tests revealed a higher force carrying capacity of the condensed specimens. Strain rate dependency and relaxation was seen in both types of collagen gel representing viscoelastic material properties. Cells embedded within the condensed collagen gel were able to produce extracellular matrix proteins and showed proliferation. Condensed collagen gel represents a mechanically improved type of biomaterial which is suitable for three-dimensional autologous chondrocyte implantation. Show more

Keywords: Condensed collagen gel, cartilage, tissue engineering, biomechanics, chondrocyte

DOI: 10.3233/BME-2010-0645

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 317-328, 2010

Authors: Bhattacharya, Sanghita | Nayak, Aniruddh | Goel, Vijay K. | Warren, Chris | Schlaegle, Steve | Ferrara, Lisa

Article Type: Research Article

Abstract: Dynamic stabilization systems are emerging as an alternative to fusion instrumentation. However, cyclic loading and micro-motion at various interfaces may produce wear debris leading to adverse tissue reactions such as osteolysis. Ten million cycles of wear test was performed for PercuDyn™ in axial rotation and the wear profile and the wear rate was mapped. A validation study was undertaken to assess the efficiency of wear debris collection which accounted for experimental errors. The mean wear debris measured at the end of 10 million cycles was 4.01 mg, based on the worst-case recovery rate of 68.2%. Approximately 40% of the particulates …were less than 5 μm; 92% less than 10 μm. About 43% of particulates were spherical in shape, 27% particulates were ellipsoidal and the remaining particles were of irregular shapes. The PercuDyn™ exhibited an average polymeric wear rate of 0.4 mg/million cycles; substantially less than the literature derived studies for other motion preservation devices like the Bryan disc and Charité disc. Wear debris size and shape were also similar to these devices. Show more

Keywords: Wear debris, wear mechanism, osteolysis, SEM

DOI: 10.3233/BME-2010-0646

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 329-338, 2010

Authors: Rozman, Janez | Mrvar, Primož | Drevenšek, Martina | Pečlin, Polona

Article Type: Research Article

Abstract: The purpose of this investigation was to assess mechanical properties of Superelastic Retraction Coil Springs for orthodontic use. To reach a goal, a test frame, comprising measuring force transducers was developed. To perform metallographic analyses of the nickel–titanium wire the samples of Superelastic Retraction Coil Springs were observed by scanning electron microscope. For in vivo testing, twenty male Wistar rats, 11–12 weeks of age, were used (Group I with Superelastic Retraction Coil Springs, Group II controls). To simulate human distraction as close as possible, all the applied Superelastic Retraction Coil Springs were modified. The Superelastic Retraction Coil Springs creating a …constant force of 25 cN were then attached between the upper left first molars and upper left incisors. Results showed that the reproducible force of 25 cN was shown over a range of 1–11 mm extension. Results also showed that the distance between aforementioned teeth, measured on days 0, 7, 14, 21, 24, 32, 37 and 40, decreased in Group I. Contrary, in Group II the distance between the teeth increased during the study (p<0.001). Show more

Keywords: Distraction osteogenesis, in vivo testing, metallographic analysis, shape memory alloys, Superelastic Retraction Coil Springs

DOI: 10.3233/BME-2010-0647

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 339-348, 2010

Authors: Li, Yuan | Lewis, Gladius

Article Type: Research Article

Abstract: For patients who are suffering debilitating and persistent pain due to vertebral compression fracture(s) and for whom conservative therapies have not provided relief, balloon kyphoplasty (BKP) is used as a surgical option. There are only a very few literature reports on the use of the finite element analysis (FEA) method to obtain biomechanical parameters of models of spine segments that include BKP augmentation at a given level. In each of these studies, the applied loading used was quasi-static. During normal activities of daily living, the patient's spine would be subject to dynamically-applied loading. Thus, the question of the influence of …the characteristics of a dynamically-applied loading cycle on biomechanical parameters of a spine that includes BKP-augmented segment(s) is germane; however, a study of this issue is lacking. We investigated this issue in the present FEA work, with the spine segment model being the L1–L3 motion segment units (MSUs) (a segment that is commonly augmented using BKP) and prophylactic BKP simulated at L2. The dynamic load was the compressive load-versus-time cycle to which the L3–L4 MSU is subjected during gait. Four cases of the cycle were considered, corresponding to slow-, normal-, fast- and very fast-paced gait. The loading cycle was applied to the superior surface of L1 while the inferior surface of L3 was fully constrained. It was found that (1) the global mean von Mises stress during the loading cycle (σVMG ), in each tissue in the model increased in going from a slow-paced gait cycle to a very fast-paced gait cycle; and (2) for the slow-paced gait cycle, with increase in frequency of the cycle, f (1≤f≤3 Hz), σVMG in each of these tissues increased. Potential uses of the present findings are identified. Show more

Keywords: Balloon kyphoplasty, finite element analysis, von Mises stress

DOI: 10.3233/BME-2010-0648

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 349-359, 2010

Authors: Lopez-Garcia, M.D.C. | Beebe, D.J. | Crone, W.C.

Article Type: Research Article

Abstract: Collagen is a key structural component of extracellular matrix and its mechanical properties, particularly its stiffness, have been shown to influence cell function. This study explores the mechanical behavior of type I collagen gels at low rates relevant to that of cell motion. The Young's modulus, E, was obtained for collagen samples of concentrations 1.3, 2 and 3 mg/ml at varying crosshead displacement rates: 0.01, 0.1 and 1 mm/min. Local strain measurement in the gage section were used for both the strain and strain rate determination. The power law models for the modulus at these low strain rates show that …the values converge as the displacement rate approaches a quasistatic state. This study provides data that was unavailable in the past on the Young's modulus of collagen at rates relevant to the cell. Show more

Keywords: Collagen, Young's modulus, strain rate, extracellular matrix

DOI: 10.3233/BME-2010-0649

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 361-369, 2010

Authors: Kahle, Maren | Wiesmann, Hans-Peter | Berr, Karin | Depprich, Rita A. | Kübler, Norbert R. | Naujoks, Christian | Cohnen, Matthias | Ommerborn, Michelle A. | Meyer, Ulrich | Handschel, Jörg

Article Type: Research Article

Abstract: Background: Surgery often leads to massive destruction of the skeleton. Cell-based bone reconstruction therapies promise new therapeutic opportunities for the repair of bone. Embryonic stem cells (ESCs) can be differentiated into osteogenic cells and are a potential cell source for bone tissue engineering. The purpose of this in vivo study was to investigate the bone formation in various constructs containing ESCs (with and without micromass technology) and insoluble collagenous bone matrix (ICBM). Methods: Murine ESCs were cultured as monolayer cultures as well as micromasses and seeded on ICBM. These constructs were implanted in immunodeficient rats. After one week, one, …two and three months CT-scans were performed to detect any calcifications and the rats were sacrificed. Results: The radiological examination shows a steep increase of the mineralized tissue in group 1 (ICBM+seeded ESC). This increase can be considered as statistical significant. In contrast, the volume of the mineralization in group 2 (ICBM+ESC-spheres) and group 3 (ESC-spheres) does not increase significantly during the study. Conclusion: ESCs in combination with ICBM do promote ectopic bone formation in vivo. Thus, this cell population as well as the biomaterial ICBM might be promising components for bone tissue engineering. Show more

Keywords: Embryonic stem cells, bone tissue engineering, ectopic bone formation, bone regeneration

DOI: 10.3233/BME-2010-0650

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 371-380, 2010

Article Type: Correction

Abstract: Related article: http://iospress.metapress.com/content/yg7112162w085863/

DOI: 10.3233/BME-2011-651

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 381-381, 2010

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 383-389, 2010

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 20, no. 6, pp. 391-392, 2010