Biomedical subjects

A Pavesio

Publications and source records attributed to A Pavesio.

8 recordsLinked to original sources

PubMed2003

Clinical aspects and strategy for biomaterial engineering of an auricle based on three-dimensional stereolithography.

At the present time, the partial and/or complete reconstruction of an auricle from autologous rib cartilage is one of most widely published techniques. In the field of tissue engineering, different techniques have been described to generate cartilage tissue using isolated chondrocytes. The basis of these tissue-engineering techniques is bioresorbable or non-bioresorbable biomaterials, which serve as a three-dimensional cell carrier. Tissue engineering of an auricle requires preformed bioresorbable biomaterials designed to fit the form of a patient's auricular defect. Three-dimensional imaging acquired from computed tomography scans or laser surface scanning has become an important tool in modern medicine. This study represents the preoperative procedures for the reconstruction of an auricle through tissue engineering in accordance with the clinical aspects. Hyaff 11, a hyaluronic acid derivative, was used as a three-dimensional cell carrier for isolated human nasoseptal chondrocytes. The chondrocytes were amplified in a conventional monolayer culture before the cells were seeded on a hyaluronic non-woven mesh and cultured in vitro for 4 weeks. The chondrogenic potential of human nasal chondrocytes in Hyaff 11 was investigated by confocal laser scanning microscopy, histology (toluidine blue) and immunohistochemistry (collagen type II). Computer-aided design (CAD) and manufacture of an auricle model with stereolithographical methods were used for the prefabrication of a bioresorbable three-dimensional cell carrier designed in the form of a patient's auricular defect. The cell carrier used was Hyaff 11, a fully benzyl-esterified hyaluronic acid derivative. Confocal laser scanning microscopy has shown good cell attachment, a homogenous distribution of amplified chondrocytes and a viability of more than 90%. After 4 weeks in vitro culture the human nasoseptal chondrocytes synthesized new cartilage with the expression of cartilage-specific collagen type II. In order to shape a patient's designed scaffold the auricle model was fitted exactly and symetrically to the contralateral side. Subsequently, the mirror image patient-specific model was used to prepare an identical scaffold model made of a fully benzyl-esterified hyaluronic acid derivative. The bioresorbable scaffold that was produced gave a satisfactory representation of auricle structure. Bioresorbable preformed biomaterials in the form of a patient's auricle defect represent an important prerequisite for the tissue engineering of autologous auricle grafts. Hyaff 11 seems to be a promising material for tissue engineering of cartilage transplants, and the application of this approach will improve conventional reconstructive surgery in the future.

Absorbable Implants↗

PubMed2001

Prevention of postsurgical adhesions with an autocrosslinked hyaluronan derivative gel.

BACKGROUND: ACP gel is a new crosslinked derivative of hyaluronic acid (HA) that displays the biocompatibility properties of its original polymer but has a higher viscosity. It has been demonstrated in an animal model that the gel reduces adhesions after gynecological surgery. The aim of the present study was therefore to investigate the efficacy of ACP gel in increasing viscosity for the prevention of adhesions after abdominal surgery. METHODS: The antiadhesive effect of ACP gel was tested in a controlled randomized study using a standardized animal model of abdominal surgery involving the creation of defects in the parietal peritoneum and muscular fascia and cecal abrasion. The animals (100 female New Zealand white rabbits) were randomly allocated into five treatment groups to receive: ACP gel (1, 2, 4, and 6%) on the injured area or no ACP gel (control). The incidence of adhesions and their grade (score 0-11) were blindly evaluated 10 weeks after surgery. RESULTS: The percentages of adhesion-free animals were 60, 84, 90, and 84% in the 1, 2, 4, and 6% ACP gel concentration groups, respectively, versus 15% in the control group (P = 0.001). The mean adhesion scores were 3.00 +/- 0.91, 1.37 +/- 0.75, 0.65 +/- 0.45, and 1.16 +/- 0.64 in the 1, 2, 4, and 6% ACP gel groups, respectively, versus 7.70 +/- 0.83 in the control group (P < 0.001). CONCLUSION: ACP gel prevents postsurgical abdominal adhesions even at a 1% concentration. This finding may be of clinical importance in situations in which large volumes of antiadhesive solution are required.

Abdomen↗

PubMed2001

Efficacy of a hyaluronan derivative gel in postsurgical adhesion prevention in the presence of inadequate hemostasis.

BACKGROUND: We previously demonstrated that an auto-cross-linked hyaluronan-based antiadhesion agent (auto-cross-linked polysaccharide [ACP] gel) was effective in postsurgical adhesion prevention after open laparotomy and laparoscopic surgery with adequate hemostasis in animal models. This study assessed the ability of different preparations of ACP gel to prevent adhesions in the presence of bleeding or inadequate hemostasis. METHODS: Ninety-seven female rabbits were subjected to a standardized surgical lesion with subsequent exudative abdominal bleeding (oozing model), and 97 animals were subjected to a standardized surgical lesion with severe abdominal bleeding (bleeding model). After injury, the animals were randomly assigned to 5 groups of treatment: 3 different preparations of ACP gel (20, 40, and 60 mg/mL), a hyaluronan-carboxymethylcellulose film, and no treatment. Three weeks after operation, the animals were killed, and the adhesions were assessed by a blinded observer who measured the length and area of the adhesions and who used the Blauer scoring system. RESULTS: All 3 preparations of ACP gel and the hyaluronan-carboxymethylcellulose film reduced adhesion formation in both models (P <.01) as measured by the number of adhesion-free animals, mean Blauer score, and the mean length and surface area of the adhesions. There were no statistical differences between the different treatment groups. CONCLUSIONS: These data suggest that different hyaluronan based agents in the presence of severe bleeding or exudative abdominal bleeding reduce de-novo postsurgical adhesion formation.

Animals↗

PubMed2000

Evaluation of interfacial properties of hyaluronan coated poly(methylmethacrylate) intraocular lenses.

Polymethylmethacrylate intraocular lenses (IOLs) were surface-modified by the linking of a overlayer of hyaluronan. In vitro experiments show that the hydrophilic HA overlayer prevents fibroblasts adhesion and greatly reduces Staphyloccous epidermidis adhesion to the IOL surface. To gain insights into the interfacial properties of untreated and hyaluronan-coated PMMA IOLs, force-distance curves were obtained by atomic force microscopy, using standard and modified tips. These measurements allow clear appreciation of the marked difference between the mechanical and chemico-physical properties at the aqueous interface of the uncoated and hyaluronan-coated lenses.

Animals↗

PubMed1998

Cartilage tissue engineering with novel nonwoven structured biomaterial based on hyaluronic acid benzyl ester.

The aim of this study was to investigate the possibility of using the benzyl ester of hyaluronic acid (HYAFF 11), a recently developed semisynthetic resorbable material, as a scaffold for the culture of human nasoseptal chondrocytes in tissue-engineering procedures of cartilage reconstruction. Different techniques such as immunohistochemistry, scanning electron microscopy, and confocal laser scanning microscopy were used to study the behavior, morphology, and phenotype expression of the chondrocytes, which were initially expanded and then seeded on the material. The nonwoven cell carrier allowed good viability and adhesivity of the cells without any surface treatment with additional substances. Furthermore, the cultured cells expressed cartilage-specific collagen type II, indicating that they were able to redifferentiate within the scaffold of HYAFF 11 and were able to retain a chondrocyte phenotype even after a long period of in vitro conditions. Nevertheless, the expression of collagen type I, which was produced by dedifferentiated or incompletely redifferentiated chondrocytes, was noticeable. Additional data were obtained by subcutaneous implantation of samples seeded with human cells in the in vivo model of the athymic nude mouse. The results after 1 month revealed the development of tissue similar to hyaline cartilage. This study is promising for the use of this scaffold for tissue engineering of cartilage replacements.

Animals↗

PubMed1998

A novel hyaluronan-based gel in laparoscopic adhesion prevention: preclinical evaluation in an animal model.

OBJECTIVE: To evaluate the effectiveness of a crosslinked hyaluronan solution (ACP gel) in the prevention of postsurgical adhesions in laparoscopic surgery. DESIGN: A randomized blinded study using a rabbit model in laparoscopic surgery. SETTING: A standardized surgical trauma in the rabbit uterine horn to induce adhesion formation. ANIMALS: Sixty-four sexually matured female New Zealand white rabbits weighing 2.5 to 3.0 kg and aged 3-4 months. INTERVENTION(S): After trauma, group 1 (n = 22) received no treatment, group 2 animals (n = 20) received oxidized-regenerated cellulose (Interceed [TC7]) in group 3 (n = 22) 5 mL of ACP gel were applied on the lesion. MAIN OUTCOME MEASURE(S): Six weeks after laparoscopy, a laparotomy was performed and the adhesions were scored according to Blauer's scoring system. RESULT(S): 66% of the untreated animals and 85% of the animals treated with Interceed presented with severe adhesions, whereas only 35% of the ACP gel treatment group had significant adhesions. The mean ( +/- SEM) increased adhesion score was 2.24 +/- 0.26 in the untreated group, 2.45 +/- 0.22 in the Interceed group, and was 1.25 +/- 0.28 in the ACP gel group. CONCLUSION(S): This study revealed that ACP gel holds promise as a novel resorbable biomaterial for the reduction of postoperative adhesions after laparoscopic surgery.

Animals↗

PubMed1997

Anti-adhesive surfaces through hyaluronan coatings.

The ability to resist adhesion of proteins, bacteria, cells and tissue is an important requirement for the surfaces of medical devices. This article describes a surface-modification process that imparts anti-adhesive properties to the surfaces of biomedical materials through the covalent binding of hyaluronan. It can be applied to a wide range of materials to yield anti-adhesive surfaces on plastics, metals and ceramics.

Bacterial Adhesion↗

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History of Pharmacy↗