Search PubMed⌕ Search

Biomedical subjects

A Hernando

Publications and source records attributed to A Hernando.

At least 55 records · Page 3Linked to original sources
PubMed1995

Assessment of cyclosporine A-induced ultrastructural changes in vascular wall using an experimental arterial autograft model.

The objective of this ultrastructural study was to assess the effects of cyclosporine A (CsA) in an experimental model of arterial autograft. Fifty female Sprague-Dawley rats weighing 250-300 g were employed. Using a microsurgical technique, an arterial autograft measuring approximately 5 mm in length was placed in the right common iliac artery. Two groups were established: group I (control), consisting of 25 animals subjected only to arterial autograft; and group II (pre- and postoperative CsA), also consisting of 25 animals which received a daily subcutaneous dose of 5 mg/kg CsA (Sandimmun, Sandoz) on the four days preceding the surgery and thereafter, until sacrifice. The animals were sacrificed on postoperative day 7, 14, 21, 30 and 50. The specimens (autografts) obtained were studied under transmission and scanning electron microscopes. In the control group, the process of endothelialization of the graft was completed by day 14. In the CsA-treated group, restoration of the endothelium took 50 days. The development of intimal hyperplasia was delayed in the treated group. There were no morphological changes in its structure when compared to the control group. The tunica media had thinned in the treated grafts, with loss of smooth muscle cells, fragmentation and lysis of the elastic lamina, presence of lipid-filled macrophages, and muscle cells with cytoplasmic lipid vacuoles. In our opinion, these results suggest that the action of CsA mainly targets on the endothelium and smooth muscle cells, exerting a toxic effect in an in vivo arterial graft model.

Animals↗
PubMed1995

Use of a fibroblastic matrix improves the results of mesothelial-cell seeding on vascular prostheses of polytetrafluoroethylene.

Mesothelial cells (MC) obtained from the human omentum are a good alternative to the use of endothelial cells (EC) as a covering for vascular prostheses of polytetrafluoroethylene (PTFE), given the antithrombogenic properties and good behavior in vitro of mesothelial cells. We studied the behaviour of mesothelial cells seeded on PTFE prostheses with an interposed fibroblastic matrix for seeding. The mesothelial cells were extracted from 30-40 g fragments of human omentum by enzymatic digestion with collagenase. The cells extracted were seeded onto small disks of PTFE to which a matrix composed of fibroblastic cells had been fixed with 5% glycerol after the fibroblasts reached convergence. Interposition of a fibroblastic matrix fixed with glycerol notably improved the adherence of the seeded mesothelial cells and the stability and durability of the cell layer formed on the prosthetic surface. The effectiveness of seeding mesothelial cells was confirmed by labelling the cells with 111In-oxine. This showed that once the cell layer had formed (24 h after seeding), the fibroblastic matrix favoured the maintenance of a stable layer of mesothelial cells 4 hours after uptake of the radioactive substance.

Blood Vessel Prosthesis↗
PubMed1994

Coatings for vascular prostheses: mesothelial cells express specific markers for muscle cells and have biological activity similar to that of endothelial cells.

The use of human omentum as an alternative to veins as a source of cells for seeding onto small-caliber vascular prostheses has awakened controversy as to the identification of the predominant cell type derived from this source. Mesothelial cells from omentum were extracted by collagenase digestion, and cultured until a monolayer was formed. These cells showed positivity for monoclonal antibodies specific for endothelial cells (anti-CD34 QBEND10), antibodies to intermediate filaments (anti-vimentin and anti-desmin) and anti-smooth muscle cell antibodies (anti-actin and anti-total actin). The mesothelial cells behaved like endothelial cells derived from vein when seeded onto polytetrafluoroethylene prostheses, showing high levels of prostacyclin production. This report provides additional evidence of the non-endothelial origin of the cells derived from human omentum.

Actins↗
PubMed1994

Arterial autografts and PTFE vascular microprostheses: similarities in the healing process.

A comparative study has been carried out dealing with the vascular healing process in two experimental vascular graft models to determine the differences or similarities between the two. One of the models consisted of the use of arterial autografts and the other of the implantation of vascular microprostheses of polytetrafluoroethylene (PTFE). The common iliac artery of female Sprague-Dawley rats was used. The length of the grafts in both models was 5 mm. A microsurgical technique was employed, and anticoagulant and antibiotic therapies were not used. The results were studied using light microscopy, transmission and scanning electron microscopies, autoradiography, and immunohistochemistry. A patency of 100% was obtained in the arterial autografts, and 87.6% in the PTFE implants. The histopathological findings were as follows: a) the mechanisms of immediate postgrafting response were similar, with marked presence of fibrin and platelet deposition in the form of a nonthrombogenic monolayer; b) a "neoadventitia" formed over the implant in both models; c) the endothelialisation was complete in both types of grafts 2 to 3 weeks after implantation; d) an intimal hyperplastic response appeared in both, although at different times (in the first week in the autografts and at one month with the PTFE); e) white cell accumulation was significantly greater on the PTFE luminal surface than on the autograft. The intimal hyperplasia was formed mainly by secretory myocytes in the autografts, while in the PTFE implants, fibrosis predominated.

Animals↗
PubMed1994

Macrophage response to experimental implantation of polypropylene prostheses.

We have assessed the macrophage response to polypropylene mesh (Marlex) implanted into the abdominal wall of New Zealand white rabbits, using RAM-11, a monoclonal antibody specific for rabbit macrophages. The response diminishes during the course of the first 90 days after implantation, although the presence of other cell types typical of foreign-body reactions increases. We have also confirmed the high degree of integration of the biomaterial into the wall achieved after 9 weeks. This has been determined using light and scanning electron microscopy. Likewise, we have observed the formation of numerous adhesions between the polypropylene mesh and the viscera of the abdominal cavity.

Animals↗
PubMed1993

Endothelial cell seeding of polytetrafluoroethylene vascular prostheses coated with a fibroblastic matrix.

One of the most serious problems with endothelial cell (EC) seeding of prosthetic materials is the poor adhesion and stability of the cells. Although several substrates that improve the initial adhesion have been assayed, the EC are lost within a limited period of time. In this study we attempted to modify the hydrophobic conditions of expanded polytetrafluoroethylene (ePTFE) by treating it with ethanol prior to seeding. In addition, we created a fibroblastic matrix that was also fixed by ethanol to the prosthetic material. In vitro studies were carried out at intervals of 24 hours and 15 days after seeding. EC from umbilical cord vein and fibroblasts from skin were seeded onto disks of PTFE with a porosity of 30 microns. The results obtained show that treatment of ePTFE with ethanol prior to EC seeding modified its permeability, preventing cellular adhesion. The seeding of fibroblasts onto ePTFE allows a coating to form at 24 hours. The EC seeded onto this matrix adhere to it, forming a monolayer that persisted throughout the entire study period. The fibroblastic matrix allows the long-term survival of the EC on ePTFE.

Blood Vessel Prosthesis↗