[Show abstract][Hide abstract] ABSTRACT: Subcutaneously implanted, in vitro engineered tissue is generally affected by the immune system of the host even in autogenous transplantation. The aim of this study was to investigate immunomodulation of subcutaneously implanted tissue-engineered cartilage transplants by intramuscular methylprednisolone application. Transplants consisted of auricular rabbit chondrocytes, polylactide-polyglycolide co-polymer fleeces and species-specific fibrin or agarose. The transplants were subcutaneously implanted in the ridge. Thereafter, animals were separated into two groups, one with and one without methylprednisolone treatment. The specimens were histologically investigated after 6 and 12 weeks. Fleece fiber degradation was complete after 12 weeks, and all transplants showed areas of calcification. The corticosteroid-treated group presented pronounced trabecular bone generation without fibrous tissue infiltration. The untreated group showed sporadic islets of calcification without coherent bone formation, and adjacent fibrous tissue had infiltrated the transplants. Native controls and corticoid-treated transplants did not exhibit bone generation or signs of fibrous tissue infiltration. This study found that immunomodulation by intramuscular methylprednisolone application protects tissue-engineered autogenous chondrocyte transplants from fibrous tissue infiltration and induces trabecular bone formation.
Full-text · Article · May 2004 · Archiv für Klinische und Experimentelle Ohren- Nasen- und Kehlkopfheilkunde
[Show abstract][Hide abstract] ABSTRACT: Tissue engineering of an elastic cartilage graft that meets the criterion for both structural and functional integration into host tissue, as well as allowing for a clinically tolerable immune response, is a challenging endeavour. Conventional scaffold technologies have limitations in their ability to design and fabricate complex-shaped matrix architectures of structural and mechanical equivalence to elastic cartilage found in the body. We attempted to investigate the potential of conventionally isolated and passaged chondrocytes (2D environment) when seeded and cultured in combination with a biomimetic hydrogel in a mechanically stable and biomimetic composite matrix to form elastic cartilage within ectopic implantation sites. In vitro cultured scaffold/hydrogel/chondrocytes constructs showed islets of cartilage and mineralized tissue formation within the cell-seeded specimens in both pig and rabbit models. Specimens with no cells seeded showed only vascularized fibrous tissue ingrowth. These studies demonstrated the potential of such scaffold/hydrogel/cell constructs to support chondrogenesis in vivo. However, it also showed that even mechanically stable scaffolds do not allow regeneration of a large mass of structural and functional cartilage within a matrix architecture seeded with 2D passaged chondrocytes in combination with a cell biomimetic carrier. Hence, future experiments will be designed to evaluate an initial 3D culture of chondrocytes, effect on cell phenotype and their subsequent culture within biomimetic 3D scaffold/cell constructs.
[Show abstract][Hide abstract] ABSTRACT: Large mandibular defects caused by trauma, infection or resection of a tumour are still a major problem for plastic and maxillofacial surgeons. The modern concept of tissue engineering combines the osteoinductive effects of osteogenic cells with a suitable scaffold structure to promote differentiation of osteoblasts and optimal matrix production. Critical size mandibular bone defects were therefore made to investigate the osteogenic potential of periosteal cells and a bioabsorbable polymer fleece (Ethisorb 510) in minipigs. Periosteal cells were isolated from four minipigs, expanded in vitro and seeded with fibrin glue into Ethisorb 510 fleeces. Tissue constructs were used to repair critical size mandibular defects and compared with two minipigs with untreated bone defects. Bone healing was evaluated after 90 and 180 days by radiographs and a histological scoring system. The radiographs showed increased radiodensity of defects filled with the cell-fibrin-fleece-constructs compared with the untreated control group after 90 and 180 days in vivo. The defects repaired by the cell-fibrin-scaffolds (180 days in vivo) obtained the highest histological mean score 2.9 (range 2-3), while defects filled by cell-fibrin-scaffolds (90 days in vivo) achieved a mean score of 2.1 (range 2-3). In contrast, the control group (n = 2) scored 1 and 2. The results show that a combination of periosteal cells and polymer fleeces may be a promising approach for clinical mandibular augmentation.
Full-text · Article · Feb 2003 · Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery
[Show abstract][Hide abstract] ABSTRACT: The established surgical methods of external ear reconstruction using autogenous tissue represent the current state of the art. Because of the limited possibilities for shaping conventional harvested autogenous rib cartilage, the cosmetic results of auricular reconstruction are frequently unsatisfactory. Tissue engineering could represent an alternative technique for obtaining a precisely shaped cartilage implant that avoids donor site morbidity and unsatisfactory cosmetic results. In this study, the reliability and quality of a tissue-engineering model for the manufacture of auricular-shaped human cartilage implants was investigated, focusing on the feasibility of the manufacturing process and the in vivo and in vitro maturation of an extracellular cartilage-like matrix. Implants were molded within an auricular-shaped silicone cylinder, and human nasal septal chondrocytes crosslinked by human fibrin within bioresorbable PGLA-PLLA polymer scaffolds were used. After an in vitro incubation of up to 6 weeks, defined fragments of the prefabricated auricular-shaped construct were implanted subcutaneously on the backs of nude mice for at least 6 to 12 weeks ( n=7). Scaffolds without cell loading served as controls. Macroscopic and histochemical examination after 3 and 6 weeks in vitro showed a solid compound of homogenously distributed chondrocytes within the polymer scaffold, leading only to a limited pericellular matrix formation. Analysis after 6 and 12 weeks of in vivo maturation demonstrated a solid tissue compound and neocartilage formation with the presence of cartilage-specific matrix components. Implants obtained shape and size during the entire period of implantation. The model of cartilage implant manufacturing presented here meets all biocompatible requirements for in vitro prefabrication and in vivo maturation of autogenous, individually shaped cartilage transplants.
Full-text · Article · Aug 2002 · Archiv für Klinische und Experimentelle Ohren- Nasen- und Kehlkopfheilkunde