Bio-Medical Materials and Engineering - Volume 5, issue 4

Authors: Lafrance, Hugues | Yahia, L'Hocine | Germain, Lucie | Guillot, Michel | Auger, François A.

Article Type: Research Article

Abstract: The living skin equivalent is one of the more advanced clinical applications in the field of tissue engineering. It is a promising therapeutic option for bum victims and a strong potential for manifold in vitro experiments. However, researchers have encountered major drawbacks in the reconstruction of the dermal layer. Peripheral anchorage of the dermal equivalent component has been a valuable solution to many of these problems. In this work, we have carried out the mechanical analysis of skin equivalent models, based on this dermal anchoring technique, with a study of their biaxial tensile properties. Differences between models were related to …the origin of collagen, either bovine or human, and on the culture techniques: immersion or at the air-liquid interface. The study was accomplished in vitro using 25.4-mm-diameter disk-shaped specimens with an indentation test. In appropriate wet condition, the specimens were punctured with a spherical tip at a quasi-static rate. We measured the load applied against the tip vs deflection up to the breaking point. Our results show that skin equivalents presented a typical exponential load-deflection relationship. All skin equivalents presented large extensibility up to 1.41 expressed in a ratio of deflection vs specimen's radius. The maximum tensile strength (0.871–1.169 Newton) and energy calculations (3.75–6.432 N·mm) was offered by living skin equivalent, made with human types I and III collagens, cultured at the air-liquid interface. In these conditions, our results suggest the tensile properties of living skin equivalents were enhanced due to the development of well stratified stratum corneum. Show more

Keywords: human collagen, dermal equivalent, skin substitute, mechanical properties, tissue engineering

DOI: 10.3233/BME-1995-5401

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 4, pp. 195-208, 1995

Authors: Yokobori, Jr., A. Toshimitsu | Miyasaka, Yoshinori | Sakurai, Minoru

Article Type: Research Article

Abstract: Osteogenesis is completed by the nucleation mechanism on crystal nuclei formation and growth after amorphous calcium phostate accretion to collagen fibers. For nuclei formation, it is necessary to have preliminary ionic diffusion such as that of Ca2+ and PO4 3− ions to this part. Therefore, promotion of ionic diffusion to this part is the first essential condition for osteogenesis. We have considered this phenomenon as the nucleation mechanism accompanied by preliminary diffusion behavior and shown the optimum mechanical condition on promoting this ionic diffusion. Furthermore, we noticed callus by callotasis as the typical example which fits this …mechanical condition and investigated its histology. However, necking occurs at the site of callus sandwiched by cortical bones due to tensile stress, three axial tensile stress in radial and tangential directions, in addition to the tensile stress occurs at the netsection of the callus due to the constraint of cortical bones. Therefore, the size of pore along the collagen lamination and hole zone becomes large under this mechanical condition and ionic diffusion such as Ca2+ , PO4 3− is liable to occur at this part. By solving the partial differential equation of the stress-induced diffusion, diffusive particles are shown to concentrate at the high three axial tensile stress region. Therefore, a high concentrated region of Ca, PO4 is achieved and selective osteogenesis due to hydroxyapatite nucleation is considered to progress in this region. Histological investigation of the callus of rabbit showed that mineralization occurs at this site and supports the theory of stress-induced diffusion on osteogenesis behavior. Show more

Keywords: osteogenesis, mineralization, calcium diffusion, tensile stress, callus

DOI: 10.3233/BME-1995-5402

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 4, pp. 209-217, 1995

Authors: Fukuchi, Noriyuki | Akao, Masaru | Sato, Atsushige

Article Type: Research Article

Abstract: Hydroxyapatite (HAp) microcrystals were synthesized by a neutralization reaction of Ca(OH)2 suspension and H3 PO4 solution using an ultrasonic homogenizer. The in vitro interaction of HAp microcrystals with rat peritoneal macrophages was investigated by measuring the viability, acid phosphatase (ACP) activity, lactate dehydrogenase (LDH) activity and intracellular calcium content. HAp calcined at 800°C and α-alumina particles (alumina) were used as comparative materials. Macrophages actively phagocytosed HAp microcrystals by dissolving them. However, no damage in macrophages exposed to HAp microcrystals was observed by transmission electron microscopy. Macrophages in the presence of HAp microcrystals showed less ACP and LDH activity …and higher intracellular calcium content than those in the presence of calcined HAp and alumina. HAp microcrystals had excellent biocompatibility to macrophages as well as sintered HAp. Show more

Keywords: hydroxyapatite microcrystals, macrophage, viability, acid phosphatase, intracellular Ca content

DOI: 10.3233/BME-1995-5403

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 4, pp. 219-231, 1995

Authors: Tada, Yoshio | Kawano, Fumiaki | Kon, Masayuki | Matsumoto, Naoyuki | Asaoka, Kenzo

Article Type: Research Article

Abstract: The mechanical properties, color and transparency of glass-ceramics are highly dependent on the ceramming temperature and/or amount of the crystal phase in the glass matrix. In this study, the influence of crystallization on the strength and color, translucency of castable ceramics containing crystalline apatite and magnesium titanate were measured. It was concluded that magnesium titanate precipitated during ceramming, appeared to be an important factor in decreasing total transmittance and in determination of the color of glass-ceramics.

Keywords: castable ceramics, color, transparency, strength, ceramming temperature

DOI: 10.3233/BME-1995-5404

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 4, pp. 233-243, 1995

Authors: Khang, Gilson | Lee, Hai Bang | Park, Joon B.

Article Type: Research Article

Abstract: Surface treatments by nonionic surfactant (Brij®) coating and air-plasma glow discharge treatment onto polysulfone have been investigated to improve its surface properties. Surface treated samples were characterized by measurement of contact angle by a goniometer, Fourier transform infrared spectroscopy in the attenuated total reflectance mode (FTIR-ATR), and electron spectroscopy for chemical analysis (ESCA). The contact angles of the nonionic surfactant coated films decreased from 66.6 ± 2.1° to nearly 0° due to hydrophilic polyethylene oxide (PEO) chain segment of the nonionic surfactant, and those of air-plasma treated films also decreased from 66.6° to about 22° with a treatment time of …less than 5 s. ESCA analysis of air-plasma treated films indicates the incorporation of oxygen molecules onto polysulfone surface lowers the water contact angle. These modified techniques can be used to prevent platelet adhesion onto polysulfone surfaces. Show more

Keywords: surface modification, polysulfone, nonionic surfactant, air-plasma treatment, water contact angle, FTIR-ATR, ESCA

DOI: 10.3233/BME-1995-5405

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 4, pp. 245-258, 1995

Authors: Khang, Gilson | Jeong, Bong Jin | Lee, Hai Bang | Park, Joon B.

Article Type: Research Article

Abstract: Expelimental results on the platelet adhesion, and CHO cell adhesion and growth onto nonionic surfactant which is composed of a long alkyl chain (n = 12~18) as the hydrophobic part, and a polyethyleneoxide (PEO) segment (n = 10~23) as the hydrophilic part coated and air-plasma treated PSf surfaces are presented in terms of PEOs functionality and surface wettability to improved blood- and cell-compatibility of polysulfone. Platelet adhesion experiments on surface treated PSf films were carried out with platelet enriched plasma (PRP) in the parallel flow chamber in vitro. Number and morphology of adhered platelets were observed by scanning electron …microscope. The number of adhered platelets on non ionic surfactant coated surfaces decreased significantly compared to the control. Also, the adhesion of platelets on to PSf substrate decreased with increasing coating concentration of nonionic surfactant. In the dry air-plasma exposed PSf sample, the adhesion of platelets decreased independently of plasma exposure time, and significant diminution of platelet adhesion was observed below about 40° of the contact angle. It is believed that less platelet adhesion is preceded by less protein adsorption due to hydrophobic dehydration interaction. In Chinese hamster ovary (CHO) cell, adhesion and growth cells grew better on the air-plasma treated PSf surfaces. From these results, it can be proposed that surface wettability of PSf is very important for cell adhesion and growth. Show more

Keywords: polysulfone, nonionic surfactant, air-plasma treatment, platelet adhesion, Chinese hamster ovary (CHO), cell, cell attachment and growth, polyethylene oxide functionality, surface wettability

DOI: 10.3233/BME-1995-5406

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 4, pp. 259-273, 1995

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 5, no. 4, pp. 275-282, 1995