Bio-Medical Materials and Engineering - Volume 18, issue 3

Authors: Pidaparti, Ramana M. | Dhanaraj, Nandhini | Meiss, Richard A.

Article Type: Research Article

Abstract: The objective of the present study is to investigate the peak forces for a tracheal smooth muscle tissue subjected to an applied longitudinal vibration following isotonic shortening. A non-linear finite element analysis was carried out to simulate the vibratory response under experimental conditions that corresponds to forced length oscillations at 33 Hz for 1 second. The stiffness change and hysteresis estimated from the experimental data was used in the analysis. The finite element results of peak forces are compared to the experimental data obtained. The comparison of results indicate that the approach and the vibratory response obtained may be useful …for describing the cross-bridge de-attachements within the cells as well as connective tissue connections characteristic of tracheal smooth muscle tissue. Show more

DOI: 10.3233/BME-2008-0514

Citation: Bio-Medical Materials and Engineering, vol. 18, no. 3, pp. 107-118, 2008

Authors: Şaşmazel, Hilal Türkoğlu | Gümüşderelioğlu, Menemşe | Gürpınar, Aylin | Onur, Mehmet Ali

Article Type: Research Article

Abstract: In this contribution, PCL (poly-ε caprolactone) scaffolds were prepared by solvent-casting/particle-leaching technique in the presence of two pore formers, PEG4000 or sucrose molecules in different quantities (0, 10, 20, 30, 40, 50, 55 w/w% PEG4000 /PCL; 10, 20 w/w% Sucrose/PCL). The surface and bulk properties of the resulting scaffolds were studied by SEM, DSC and FTIR. SEM photographs showed that, macroporosity was obtained in the PCL structures prepared with sucrose crystals while microporous structure was obtained in the presence of PEG4000 molecules. Average pore diameters calculated from SEM photographs were 40.1 and 191.2 μm for 40% PEG4000 /PCL …and 10% Sucrose/PCL scaffolds, respectively. The DSC and FTIR results confirmed that there is no any interaction between pore formers and PCL during structural formation, and both pore formers, PEG4000 and sucrose, remained independently in the scaffolds. L929 mouse fibroblast cells were seeded onto PCL structures and maintained during 7 days to evaluate cell proliferation. Cell culture results showed that, 10% Sucrose/PCL scaffold was the most promising substrate for L929 cell growth due to 3-D architecture and macroporous structure of the scaffold. Show more

Keywords: Poly(ε-caprolactone), poly(ethylene glycol), sucrose, porous structures, L929 mouse fibroblasts, tissue engineering

DOI: 10.3233/BME-2008-0515

Citation: Bio-Medical Materials and Engineering, vol. 18, no. 3, pp. 119-128, 2008

Authors: Nakamura, Sayaka | Yamada, Yoichi | Baba, Shunsuke | Kato, Harumi | Kogami, Hiroyuki | Takao, Makoto | Matsumoto, Naoyuki | Ueda, Minoru

Article Type: Research Article

Abstract: Mesenchymal stem cells (MSCs) are multipotent cells that have potential to differentiate into various phenotypes and appear useful for therapeutic applications in regenerative medicine. Mesenchymal Stem Cell Basal Medium (MSCBM; Cambrex® ) is a widespread and suitable medium used in MSC cultivation, but it is extremely difficult to use generally for clinical treatment because of its unclear traceability and cost. Assessment of cost-effectiveness is a critical issue for successful practical application; therefore, we have evaluated the effects of a generally used medium, Dulbecco's Modified Eagle's Medium (D-MEM) on the expansion of MSCs in comparison with MSCBM. To isolate human MSCs, …bone marrow aspirates were taken and cultured in MSCBM or D-MEM. Proliferation assay indicated that MSCs isolated in both media showed a similar growth rate. When supplemented with osteo-inductive reagents, alkaline phosphatase activity was not significantly different between cells in D-MEM and MSCBM. Moreover, the cells expressed identical mesenchymal lineage markers, but not endothelial and hematopoietic lineage markers. Our findings suggest that cells obtained from bone marrow and cultured in D-MEM might possess proliferative capacity and the potential to differentiate into an osteogenic lineage. In conclusion, D-MEM might be a suitable basal medium for the cultivation of MSCs for clinical applications. Show more

Keywords: Mesenchymal stem cells, clinical translation, practical use, culture conditions, Dulbecco's Modified Eagle's Medium

DOI: 10.3233/BME-2008-0516

Citation: Bio-Medical Materials and Engineering, vol. 18, no. 3, pp. 129-136, 2008

Authors: Visco, A.M. | Campo, N. | Torrisi, L. | Cristani, M. | Trombetta, D. | Saija, A.

Article Type: Research Article

Abstract: Ultra high molecular weight polyethylene, both pure and electron beam irradiated, was exposed to air and hyaluronic acid. Physical and mechanical analyses were performed in order to check the polymeric change due to the treatment. Pure UHMWPE, in fact, was modified by the hyaluronic acid that plasticizes the polymer. The electron irradiation cross links the chains and prevents their sliding in acid presence. A low irradiation dose is preferable rather than an high one. Low doses induce low amount of free radicals, witch react with oxygen and hyaluronic acid inducing low polymer degrade maintaining the initial mechanical performance. High doses …degrade significantly the polymer properties.100 kGy irradiation in air can be applicable on the polyethylene as well as a compromise between the low mechanical performance improving and the material degradation. Show more

Keywords: UHMWPE, electron beam, degradation, mechanical characterization

DOI: 10.3233/BME-2008-0517

Citation: Bio-Medical Materials and Engineering, vol. 18, no. 3, pp. 137-148, 2008

Authors: Crowley, J. | Chalivendra, V.B.

Article Type: Research Article

Abstract: An experimental study of Ultra-High Molecular Weight Polyethylene (UHMWPE) and hydroxyapatite (HAP) nanocomposites for the purpose of joint prosthesis is investigated under quasi-static and dynamic loading conditions. By employing compression mold process, five different volume fractions of hydroxyapatite nanoparticle reinforced nanocomposites are made. Quasi-static tension and compression tests are performed using ASTM test methods. Dynamic compression characterization is performed using split Hopkinson pressure bar technique. The nanocomposite performance as a function of volume fraction under a typical loading rate is investigated. The results of the fabricated nanocomposites are compared with currently employed UHMWPE in the joint implants. For comparison purposes, …separate sets of tests are performed on currently employed UHMWPE. This comparison provides a valid measure to identify the optimum volume fraction of hydroxyapatite that can be used without compromising the integrity of the UHMPWPE in joint prosthesis. Show more

Keywords: UHMWPE, hydroxyapatite, nanocomposite, split Hopkinson pressure bar, hip replacement prosthesis, knee prosthesis

DOI: 10.3233/BME-2008-0518

Citation: Bio-Medical Materials and Engineering, vol. 18, no. 3, pp. 149-160, 2008

Authors: Asano, Takuji | Tsuru, Kanji | Hayakawa, Satoshi | Osaka, Akiyoshi

Article Type: Research Article

Abstract: Among the clinical treatments of Familial Hyper cholesterolemia patients to reduce the concentration of low density lipoprotein (LDL), blood purification therapy is most suitable in which a blood-compatible adsorbent is employed. In the present study, alumina powders were prepared via a sol–gel route to develop a LDL-adsorbent Aluminum tri2-propoxide was hydrolyzed and subsequently calcined up to 1200°C. Surface charge density and pore size distribution were measured, and the phases were identified. The alumina calcined above 400°C had excellent blood compatibility in terms of endogenous clotting parameters, i.e., partial thromboplastin time: (PTT), prothrombin time: (PT), and the amount of fibrinogen: (Fib). …The amount of LDL-adsorption (ΔWLDL ) increased with the calcining temperature, showing a good linear correlation to surface charge density. The 1200°C sample consisted only of α-alumina, and was greatest in ΔWLDL . All samples involved pores smaller than 20 nm but not the pores large enough to accommodate LDL molecules (20–25 nm). From those results, it was concluded for the present alumina particles that the surface charge density was the primary factor and that the chemical activity of α-alumina also contributed to the excellent LDL-adsorption for the 1200°C sample, while entrapping LDL in the pores was not an active mechanism. Show more

Keywords: Alumina, low density lipoprotein, adsorbents, charge density, sol–gel method

DOI: 10.3233/BME-2008-0519

Citation: Bio-Medical Materials and Engineering, vol. 18, no. 3, pp. 161-170, 2008