Biomedical subjects

B Ziegelaar

Publications and source records attributed to B Ziegelaar.

4 recordsLinked to original sources

PubMed2004

[Tissue-engineered cartilage in a prefabricated microvascularized flap].

INTRODUCTION: In reconstructive surgery, the integration of tissue-engineered cartilage in a prefabricated free flap may make it possible to generate flaps combining a variety of tissue components to meet the special requirements of a particular defect. The aim of the present study was to establish the technique of prefabricating a microvascular free flap by implanting a vessel loop under a skin flap in a rabbit model. The second aim was to gather experience with prelaminating the flap with autologous tissue-engineered cartilage in terms of matrix development, inflammatory reaction and host-tissue interaction. METHODS: The microvascular flap was created by implanting a vessel loop under a random pattern abdominal skin flap. The tissue-engineered cartilage constructs were made by isolating chondrocytes from auricular biopsies. Following a period of amplification, the cells were seeded onto a non-woven scaffold made of a hyaluronic acid derivative and cultivated for 2-3 weeks. One cell-biomaterial construct was placed beneath the prefabricated flap, and the others were placed subcutaneously under the abdominal skin and intermuscularly at the lower extremity. In addition, a biomaterial sample without cells was placed subcutaneously as a control. All implanted specimens were left in position for 6 or 12 weeks. After explantation, the specimens were examined by histological and immunohistological methods. The prefabricated flap was analyzed by angiography. RESULTS: The prefabricated flaps showed a well-developed network of blood vessels formed by neovascularization between the implanted vessel loop and the original random-pattern blood supply. The tissue-engineered constructs remained stable in size and showed signs of tissue similar to hyaline cartilage, as evidenced by the expression of cartilage-specific collagen type II and proteoglycans. No hints of inflammatory reactions were observed. CONCLUSION: These results show the potential of prefabricated flaps as custom-made flaps for reconstructive surgery in difficult circumstances, more or less independent of anatomical prerequisites. Cartilage tissue engineering provides a 3-dimensional structure with minimal donor-site morbidity.

Animals↗

PubMed2002

[Mesenchymal stem cells--a new pathway for tissue engineering in reconstructive surgery].

INTRODUCTION: Mesenchymal stem cells (MSC) have the capacity to differentiate into chondrocytes with the synthesis of cartilage. This report presents the use of human adult bone marrow derived mesenchymal stem cells for tissue engineering of autologous cartilage grafts. METHODS: Human bone marrow aspirates were obtained from the iliac crest and fractionated on a Percoll gradient. The isolated hMSC were plated at 20 x 10 (6) cells per 100 mm (2) culture dish. After 21 days in culture at 37 degrees C with 5 % CO 2, the adherent multiplied MSC were trypsinized, counted, and tested for viability by trypan blue assay. The hMSCs were loaded into a sterile 15 ml polypropylene tube (0.5 Mio cells/ml) and centrifuged on the bottom of the tube at 500 g for 5 minutes. The MSC were cultivated for 3 weeks in vitro in a specific chondrogenetic medium composed of Dulbecco's Modified Eagles Medium-High Glucose supplemented with 10 ng/ml transforming growth factor-beta 1, 1 % ITS-Premix medium, 80 micro M ascorbic acid, and 100 nM dexamethasone. RESULTS: Histological and immunohistochemical studies performed after 3 weeks in three dimensional culture demonstrated the expression of cartilage specific collagen type II and X as well as proteoglycans. CONCLUSION: Human adult mesenchymal stem cells derived from bone marrow aspirates have the ability to differentiate into chondrocytes under specific culture conditions by growth factors. The use of adult mesenchymal stem cells may be a promising tool for tissue engineering of autologous cartilage grafts in reconstructive surgery in the future.

Adult↗

PubMed2000

Development and clinical assessment of an artificial cornea.

Keratoprosthesis research has been a gradual, rather fragmentary process with advances being made by isolated groups of researchers. This has arisen partly because of poor funding in the area; research groups which have achieved commercial support have often had constraints upon the full disclosure of their findings. Despite these difficulties there has been real progress over the last decade by several independent groups. This article concentrates upon our own development of a hydrogel core-and-skirt keratoprosthesis, the Chirila KPro, in order to illustrate the scientific and clinical problems common to keratoprosthesis research. Pilot data from a clinical trial is presented and the priorities for future research are discussed.

Animals↗

PubMed1998

Clinical results of implantation of the Chirila keratoprosthesis in rabbits.

AIMS/BACKGROUND: An ideal keratoprosthesis (KPro) would closely resemble a donor corneal button in terms of its surgical handling, optics, and capacity to heal with host tissue in order to avoid many of the complications associated with the KPros which are currently in clinical use. This study was carried out to assess the long term clinical outcomes on implantation of the core and skirt poly(2-hydroxyethyl methacrylate) KPro in animals. METHODS: 20 KPros were made and implanted as full thickness corneal replacements into rabbits and followed for up to 21 months to date. RESULTS: 80% of the prostheses have been retained, with a low incidence of complications such as cataract, glaucoma, and retroprosthetic membrane formation which are frequently associated with KPro surgery. CONCLUSIONS: KPros of this type may offer promise in the treatment of patients for whom penetrating keratoplasty with donor material carries a poor prognosis. Refinement of the KPro and further animal trials, including implantation into abnormal corneas, are however mandatory before human implantation could be planned.

Animals↗