Biomedical subjects

Natalia Serrano

Publications and source records attributed to Natalia Serrano.

5 recordsLinked to original sources

PubMed2005

[Composite prostheses for the repair of abdominal wall defects: comparative study of physical and/or chemical barriers].

INTRODUCTION: Composite biomaterials designed for the repair of abdominal wall defects are usually composed of a reticular component and a second component, or barrier, which is laminar (absorbable or non-reabsorbable) and which is placed in contact with the visceral peritoneum. This study was designed to evaluate how the composition of this second component affects the biological behavior of the biomaterial and the formation of adhesions. MATERIAL AND METHODS: Defects (7 x 5 cm) comprising all the tissue planes except the skin were created in the anterior abdominal wall of white, New Zealand rabbits. In group A (n = 12) the defects were then repaired with composite prostheses with a non-reabsorbable physical barrier, polypropylene + ePTFE (PL + ePTFE) and PL + polyurethane (PL + PU). In group B (n = 12) the defects were repaired with a reabsorbable chemical barrier, polyester + a polyethyleneglycol/glycerol film (PO + gl) and PL + hyaluronate (PL + hy). Fourteen days after surgery, the animals were sacrificed and specimens were taken for light and scanning electron microscopy and immunohistochemical labeling for macrophages (RAM-11). Adhesions forming at the prostheses/visceral peritoneum interface were quantified. RESULTS: All the materials showed optimal tissue infiltration and mesothelialization. Adhesion formation was similar in prostheses with a physical barrier (PL + ePTFE, 0.49 +/- 0.14%; PL-PU, 0.29 +/- 0.2%). In contrast, those with a chemical barrier showed a significant difference in adhesion formation (PO + gl, 0.55 +/- 0.06%; PL + hy, 18.55 +/- 4.96%; p < 0.05). CONCLUSIONS: Physical barriers seem to induce similar adhesions, while adhesions formed to prostheses with chemical barriers can vary considerably, possibly depending on the chemical composition of the barrier.

Animals↗

PubMed2005

[Polypropylene and polydioxanone show similar biomechanical efficacy in midline closure].

INTRODUCTION: After laparotomy, the incidence of incisional hernia is high, especially when the abdomen in opened along the linea alba, a weak structure of the abdominal wall. This study was designed to evaluate the biomechanical resistance of midline closure using the same surgical technique but two different types of suture material, a long-lasting absorbable material and a non-absorbable material. MATERIAL AND METHODS: A 7.5 cm midline laparotomy was performed in 48 New Zealand White rabbits. The surgical wound was then repaired with an en masse running suture using polypropylene 4/0 or polydioxanone 4/0. Animals not subjected to surgery were used as controls. Morphological, immunohistochemical and biomechanical tests were undertaken 3 weeks, 6 weeks and 6 months after surgery. RESULTS: Both types of suture gave rise to scar tissue composed of collagen fibers concentrically arranged around the suture filaments. Six months after surgery, the polydioxanone suture had almost completely degraded. The macrophage response steadily diminished over time, although it was significantly greater in wounds closed by polydioxanone suture. No significant differences were found in the biomechanical strength provided by the two types of suture. CONCLUSIONS: After laparotomy closure at the linea alba, both suture materials showed optimal biological behavior. The composition of the suture material did not affect the tensile strength of the repair zone.

Animals↗

PubMed2004

Improved biomechanical resistance using an expanded polytetrafluoroethylene composite-structure prosthesis.

We designed a composite-structure (laminar-reticular) prosthesis using expanded polytetrafluoroethylene (ePTFE) as the biomaterial in an attempt to improve the biomechanical resistance of the same biomaterial in the form of a single lamina. Defects (7 x 5 cm) were created in the abdominal wall of male white New Zealand rabbits (n = 24). The defects, which comprised all the wall layers except the skin, were then repaired with one of two types of ePTFE prosthesis. One was a latest generation laminar prosthesis (DualMesh, or Gore-Tex) and the other was a composite of in-house design (CV-4 mesh composite) made by suturing a mesh woven out of ePTFE thread to an ePTFE lamina. After sacrificing the animals at 14 or 90 days after surgery, implant specimens were subjected to morphologic analysis (light microscopy and scanning electron microscopy); and adhesion formation, neoperitoneal thickness, and biomechanical strength were evaluated. No significant differences were recorded between the two prosthesis regarding the consistency of adhesions or the area occupied by adhesions (DM 0.17 +/- 0.06; CV-4 mesh composite 0.18 +/- 0.08 cm2) (p > 0.05). Notably, improved tissue integration was achieved using the composite prosthesis; its reticular side became infiltrated by dense connective tissue that enveloped the mesh filaments. In contrast, the DM prosthesis became encapsulated by host tissue. The neoperitoneum induced by both prostheses was homogeneous and orderly, with a layer of typical mesothelial cells lining its inner surface. The thickness of the neoperitoneum was similar (p > 0.05) for the two implants (385.0 +/- 3.4 vs. 390 +/- 3.1 microm), although significantly higher (p < 0.05) mechanical resistance values were recorded for the composite prosthesis (26.75 +/- 3.71 vs. 14.11 +/- 3.71 N). Our findings suggest that the use of a reticular and a laminar ePTFE layer in the same prosthesis leads to better repair and biomechanical behavior compared to the use of a single-structure laminar implant.

Abdominal Wall↗

PubMed2004

Temporary closure of the abdomen using a new composite prosthesis (PL-PU99).

BACKGROUND: Temporary abdominal wound closure is sometimes desirable when tension-free approximation of the wound edges is impractical or when reexploration is planned. METHODS: The behavior of a composite prosthesis (PL-PU99) designed by our group was evaluated as a method of temporary abdominal closure in white New Zealand rabbits. After a 7 cm long midline laparotomy, a spindle-shaped 4 cm (maximum width) by 7 cm (length) fragment of PL-PU99 was sutured to the edges of the peritoneal, muscular, and fascial abdominal tissues, so that the biomaterial remained in contact with the exterior. The PL-PU99 composite is composed of a polypropylene mesh adhered to a sheet of polyurethane with an acrylic cement. At 7 and 14 days after implant, animals were sacrificed and specimens taken for morphological, ultrastructural, morphometry of the neoperitoneum, and immunohistochemical (macrophage reaction, RAM-11) analysis. RESULTS: No death or signs of infection or rejection of the prostheses were recorded. No adhesions could be macroscopically observed between the composite and the intestinal loops. The biomaterial achieved a good seal, no leakage of fluids being detected. Fourteen days after implant, the neoperitoneum formed on the prosthesis was of an even structure and was made up of organized, vascularized connective tissue covered by an uninterrupted mesothelium. CONCLUSIONS: The PL-PU99 prosthesis shows optimal behavior at the prosthesis/visceral peritoneum interface, making it ideal for its use in the temporary closure of the abdomen. The implanted composite may also prove useful for the permanent repair of the abdominal wall.

Abdominal Wall↗

PubMed2004

Restoring the endothelium of cryopreserved arterial grafts: co-culture of venous and arterial endothelial cells.

The use of arterial homografts in clinical practice is becoming increasingly common, yet there is an urgent need to address one of the most well-established problems associated with their use: the loss of integrity of the endothelium following cryopreservation. The partial lack of endothelium causes contact between the extracellular matrix and blood flow, which, in turn, often gives rise to thrombosis and/or restenosis. Our objective was first to attempt to replace the arterial endothelial cells lost during the cryopreservation process by seeding autologous venous endothelial cells, and to evaluate the behaviour of venous and arterial endothelial cells in co-culture. The idea was to establish whether venous endothelial cells would be accepted by arterial endothelial cells and could therefore be used to restore the endothelial lining for the subsequent use of these vessels in in vivo grafting procedures. For the co-culture experiments, endothelial cells were obtained from the jugular vein and both iliac arteries of the minipig by treatment with 0.1% type I collagenase. The venous endothelial cells were fluorescently labelled with the membrane intercalating dye PKH26. Equal numbers of venous and arterial endothelial cells were mixed and co-cultured for 24h, 48h or 4 days. Cell viability, determined by 2% trypan blue staining and the TUNEL method, was established before and after fluorescence labelling. Cellular activity was determined by estimating PGI2 levels in the cultures. The proliferation index was established by [H(3)]thymidine (1muCi/ml) in the cell culture medium. For the in vivo tests, 5 cm length segments of minipig iliac artery were used to establish the groups: control (n = 6), fresh arterial segments; group I (n = 16), cryopreserved arterial segments and group II (n = 16), cryopreserved arterial segments seeded with autologous venous endothelial cells. The cryopreserved vessels in group II were seeded by flooding with a labelled venous endothelial cell suspension. Once seeded, the arterial segments were included in an in vitro flow circuit. All the specimens were processed for fluorescence and light microscopy, and scanning electron microscopy. The denuded endothelial surface was determined in each group. Cell death was evaluated by the TUNEL method. We confirmed the existence of intercellular PECAM1-type junctions between venous (PKH26+) and arterial cells in co-culture and the functional activity of the cells. The cryopreserved arterial segments showed a well-preserved wall structure. However, different size areas of marked endothelial denudation were detected. After seeding with labelled cells (PKH26+), these denuded areas of the cryopreserved artery were entirely covered by fluorescent cells. After seeding, a drop in the proportion of damaged endothelial cells was recorded. Despite some loss of seeded cells after inclusion in the in vitro flow circuit, the endothelial cell count was not significantly different to those recorded for control, non-cryopreserved specimens. In conclusion arterial and venous endothelial cells growing in co-culture modify their behaviour to form multilayers. The two cell populations form normal PECAM1 junctions and preserve their functional properties. Seeding autologous venous endothelial cells on the luminal surface of cryopreserved arterial segments serves to restore the integrity of the endothelial layer.

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