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Biomedical subjects

S M Malmonge

Publications and source records attributed to S M Malmonge.

7 recordsLinked to original sources
PubMed2002

Adhesion and morphology of fibroblastic cells cultured on different polymeric biomaterials.

Cell adhesion is influenced by the physical and chemical characteristics of the materials used as substrate for cell culturing. In this work, we evaluated the influence of the morphological and chemical characteristics of different polymeric substrates on the adhesion and morphology of fibroblastic cells. Cell growth on poly (L-lactic acid) [PLLA] membranes and poly(2-hydroxy ethyl methacrylate) [polyHEMA], poly(2-hydroxy ethyl methacrylate)-cellulose acetate [polyHEMA-CA] and poly(2-hydroxy ethyl methacrylate)-poly(methyl methacrylate-co-acrylic acid) [polyHEMA-poly(MMA-co-AA)] hydrogels of different densities and pore diameters was examined. Cells adhered preferentially to more negatively charged substrates, with polyHEMA hydrogels being more adhesive than the other substractes. The pores present in PLLA membranes did not interfere with adhesion, but the cells showed a distinctive morphology on each membrane.

Journal Article↗
PubMed2000

PolyHEMA and polyHEMA-poly(MMA-co-AA) as substrates for culturing Vero cells.

Poly (2-hydroxyethyl methacrylate), polyHEMA, is known to prevent cellular attachment and spreading. This hydrogel is used to culture cells not dependent on anchorage. Blending polyHEMA with a copolymer of methyl methacrylate and acrylic acid introduces negative charges to the hydrogel and improves its mechanical characteristics. PolyHEMA and the blend were tested for attachment and proliferation of Vero cells. Dense and porous samples of the hydrogels were used. Attachment assays included cellular quantification with MTT photometry and cellular morphology with the scanning electron microscopy after 2 h culture. Proliferation assays were carried out with 5 and 10 days culture. Cellular morphology included cytochemistry of resin sections and scanning electron microscope observations. Hydrogels allowed a few cells to attach and proliferate. The cells growing on the surface of hydrogels were organized in various layers and showed a differential morphology. Cells located inside the pores remained rounded. The hydrogels showed the possibility of inducing differentiated phenotypic expression.

Journal Article↗
PubMed2000

Devices for use as an artificial articular surface in joint prostheses or in the repair of osteochondral defects.

The covering of ultra high molecular weight polyethylene (UHMWPE) and calcium hydroxyapatite (HA)/tricalcium phosphate (TCP) porous solid substrate with polyHEMA hydrogel has been studied aiming at the development of devices to be used as artificial articular surfaces in joint prosthesis or osteochondral repair grafts. Commercial porous UHMWPE was used. Ceramic porous substrate was prepared by load compaction of an HA and TCP powder mixture obtained by aqueous precipitation technique. Two different compaction loads and grain size distribution was used. Polymer particles were added to the powder mixture in order to increase the substrate porosity after the sintering process. The porous substrate was covered with polyHEMA hydrogel by in situ polymerization. Morphological analysis (SEM) showed that a hydrogel layer formed in the porous solid top surface was fixed to the substrate by mechanical interlocking because the porous surface was filled by the hydrogel. After hydrogel covering, the resultant devices showed a decrease in the compressive elastic modulus that was influenced by the porous substrate material.

Calcium Phosphates↗
PubMed2000

Artificial articular cartilage: mechanoelectrical transduction under dynamic compressive loading.

The search for biomaterials to be used as an artificial articular cartilage in joint restoration is a challenging research area. Because the articular cartilage plays a fundamental role in joint function, the biomaterial has to be able to mimic the behavior of the natural healthy surface. Articular cartilage is a biphasic material composed by a solid extracellular matrix and a fluid phase, the synovial fluid. When the tissue is pressed, there is a mechanoelectrical transduction that is believed to modulate the cellular activity of chondrocytes, being fundamental for tissue repair. This work aimed at the development of hydrogels for use as an artificial articular cartilage. Hydrogels with negative groups fixed in the macromolecular network were obtained by copolymerizing 2-hydroxyethyl methacrylate with acrylic acid. The obtained hydrogels showed a mechanoelectrical transduction under dynamic compressive loading with potential amplitude increasing with fixed charge density values.

Acrylates↗
PubMed2000

Biomechanical and histological evaluation of hydrogel implants in articular cartilage.

We evaluated the mechanical behavior of the repaired surfaces of defective articular cartilage in the intercondylar region of the rat femur after a hydrogel graft implant. The results were compared to those for the adjacent normal articular cartilage and for control surfaces where the defects remained empty. Hydrogel synthesized by blending poly(2-hydroxyethyl methacrylate) and poly(methyl methacrylate-co-acrylic acid) was implanted in male Wistar rats. The animals were divided into five groups with postoperative follow-up periods of 3, 5, 8, 12 and 16 weeks. Indentation tests were performed on the neoformed surfaces in the knee joint (with or without a hydrogel implant) and on adjacent articular cartilage in order to assess the mechanical properties of the newly formed surface. Kruskal-Wallis analysis indicated that the mechanical behavior of the neoformed surfaces was significantly different from that of normal cartilage. Histological analysis of the repaired defects showed that the hydrogel implant filled the defect with no signs of inflammation as it was well anchored to the surrounding tissues, resulting in a newly formed articular surface. In the case of empty control defects, osseous tissue grew inside the defects and fibrous tissue formed on the articular surface of the defects. The repaired surface of the hydrogel implant was more compliant than normal articular cartilage throughout the 16 weeks following the operation, whereas the fibrous tissue that formed postoperatively over the empty defect was stiffer than normal articular cartilage after 5 weeks. This stiffness started to decrease 16 weeks after the operation, probably due to tissue degeneration. Thus, from the biomechanical and histological point of view, the hydrogel implant improved the articular surface repair.

Animals↗
PubMed2000

Morphology of fibroblastic cells cultured on poly(HEMA-co-AA) substrates.

Fibroblastic cells in culture are characteristically elongated and grow in monolayers. This growth pattern can be modified by different factors, such as substrate interaction. It is characteristic of hydrogels made of poly(2-hydroxyethylmethacrylate) (polyHEMA) that they inhibit cellular attachment and spreading. Vero cells were cultured on porous samples of polyHEMA and the copolymer poly(HEMA-co-AA) with 7.5% (w/w) and 15% (w/w) acrylic acid. Cultures were maintained for 2 and 10 days in HAM F10 medium with 10% foetal calf serum. Hydrogel samples were processed for light microscopy and scanning electron microscopy. The round Vero cells proliferated on the hydrogels and were principally located inside the pores. Some cells were aggregated, but no extracellular matrix was found. The copolymer with 15% (w/w) acrylic acid was the most suitable substrate and should be used in future tests of morphological differentiation and induction of cellular function.

Animals↗