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Biomedical subjects

O Schultz

Publications and source records attributed to O Schultz.

16 recordsLinked to original sources
PubMed2006

[Acute mesenteric ischemia in a patient with relapsing polychondritis].

We report about a 43-year old woman with relapsing polychondritis, admitted with progressive malaise, fatigue, anorexia and profound weight loss. Two years ago a nasal chondritis with characteristic changes of the nasal profil, scleritis, laryngitis and unspecific general symptoms (fever, fatigue, signs of a systemic inflammation) developed and relapsing polychondritis was diagnosed. The patient was treated initially with azathioprine followed by methotrexate in combination with ciclosporine and glucocorticoids. During the hospitalization her condition slowly worsened, and crampy abdominal pain developed subsequently with massive tenderness, rebound and guarding. The clinically presumed diagnosis of ileus and peritonitis was radiomorphologically confirmed with signs of enteric perforation and a laparatomy was performed. A complete occlusion of the A. mesenterica superior and stenosis of the truncus coeliacus were diagnosed followed by a revascularization with an aorto-mesenteric bypass and subsequent resection of the necrotic ischemic ileum. An association with various autoimmune disorders including vasculitic syndromes is well known for relapsing polychondritis. The case demonstrated a progressive mesenteric ischemia with the acute exacerbation caused by a vasculitic mesenterial occlusion. The unusual presentation should be considered in the differential diagnosis of uncommon abdominal symptoms during the course of relapsing polychondritis.

Acute Disease↗
PubMed2001

[Establishment of an in vitro model for rheumatoid arthritis as test system for therapeutical substances].

In our Tissue Engineering group a 3D in vitro model for rheumatoid Arthritis (in vitro pannus) was established with the aim to develop a standardized drug-screening test to analyze the effects of drugs and different biological substances. The advanced model consists of chondrocyte pellet cultures interacting with rheumatoid arthritis (RA) synovial cell cultures. To establish interactive 3D co-cultures defined rheumatoid arthritis synovial cell populations were centrifuged directly on chondrocyte pellet cultures. Histochemical stainings during time of co-culture revealed obvious invasion by RA synovial cell populations into the chondrocyte matrix. Gene expression analysis showed a downregulation of collagen type II expression in chondrocytes within 2 weeks after co-culture with RA synovial cells. Those interactive co-cultures allow the study of single cell populations as well as the cellular interactions in this system under in vitro conditions. Thus, the established co-culture model may be suitable for routine screening tests, which can be useful in supplementing animal experiments in basic research and drug testing.

Animal Testing Alternatives↗
PubMed2000

The influence of transforming growth factor beta1 on mesenchymal cell repair of full-thickness cartilage defects.

To repair full-thickness articular cartilage defects in rabbit knees, we transplanted periosteal cells in a fibrin gel and determined the influence of transforming growth factor beta (TGF-beta) in vitro. Alginate served as a temporary supportive matrix component and was removed prior to transplantation. The defects were analyzed macroscopically, histologically, and electron microscopically, and evaluated with a semi-quantitative score system. Periosteal cell transplants showed a chondrogenic differentiation, which results in the development of embryonic-like cartilage tissue after 4 weeks and complete resurfacing of the patellar groove after 12 weeks. In the control groups, no repair was observed. Under the influence of TGF-beta1 we observed a reduction of the cartilage layer, whereas the osteochondral integration and the zonal architecture were improved. Periosteal cell-beads are stable cartilage transplants and have stiffness and elasticity enough for easy and sufficient transplant fixation. Further investigations are necessary to optimize the application of TGF-beta1 for cartilage repair.

Alginates↗
PubMed2000

Emerging strategies of bone and joint repair.

The advances in biomedicine over the past decade have provided revolutionary insights into molecules that mediate cell proliferation and differentiation. Findings on the complex interplay of cells, growth factors, matrix molecules and cell adhesion molecules in the process of tissue patterning have vitalized the revolutionary approach of bioregenerative medicine and tissue engineering. Here we review the impact of recent work in this interdisciplinary field on the treatment of musculoskeletal disorders. This novel concept combines the transplantation of pluripotent stem cells, and the use of specifically tailored biomaterials, arrays of bioactive molecules and gene transfer technologies to direct the regeneration of pathologically altered musculoskeletal tissues.

Bone Diseases↗
PubMed2000

Matrix-mixed culture: new methodology for chondrocyte culture and preparation of cartilage transplants.

For cartilage engineering a variety of biomaterials were applied for 3-dimensional chondrocyte embedding and transplantation. In order to find a suitable carrier for the in vitro culture of chondrocytes and the subsequent preparation of cartilage transplants we investigated the feasibility of a combination of the well-established matrices fibrin and alginate. In this work human articular chondrocytes were embedded and cultured either in alginate, a mixture of alginate and fibrin, or in a fibrin gel after the extraction of the alginate component (porous fibrin gel) over a period of 30 days. Histomorphological analysis, electron microscopy, and immunohistochemistry were performed to evaluate the phenotypic changes of the chondrocytes, as well as the quality of the newly formed cartilaginous matrix. Our experiments showed that a mixture of 0.6% alginate with 4.5% fibrin promoted sufficient chondrocyte proliferation and differentiation, resulting in the formation of a specific cartilage matrix. Alginate served as a temporary supportive matrix component during in vitro culture and can be easily removed prior to transplantation. The presented tissue engineering method on the basis of a mixed alginate-fibrin carrier offers the opportunity to create stable cartilage transplants for reconstructive surgery.

Alginates↗
PubMed2000

[Chondrocyte transplantation in PGLA/polydioxanone fleece].

The transplantation of chondrogenic cells in a supportive carrier structure proved to be a promising alternative for the treatment of cartilage defects. In the study presented we focused on the transplantation of allogeneic chondrocytes in a biodegradable polymer scaffold (PGLA/Polydioxanon) in articular cartilage defects in a rabbit defect model. Isolated allogeneic chondrocytes embedded in a PGLA polymer scaffold were transplanted into osteochondrogenic defects of the patellar groove and compared with empty defects and transplants of polymer scaffolds without cells. The histological and histochemical analysis was performed after 4 and 12 weeks. The transplant integration and the architecture of the newly formed cartilage were evaluated with a semiquantitative score. After 4 weeks the development of a hyaline-like cartilage tissue of the cell-polymer-transplants was observed, after 12 weeks the defects were nearly completely filled with hyaline-like cartilage. The biodegradation of the polymer construct did not affect the histological structure of the transplant area. Defects of the groups with empty defect and polymer transplants without cells revealed no or insufficient healing indices. The study demonstrated that biodegradable polymers served as suitable carriers for the chondrocyte transplantation, which is due to the in-vitro establishment of a semi-solid cartilage transplant and the resulting effective transplant fixation into the defect. In-vivo the polymer cell transplants seem to provide a supportive microenvironment for the development of hyaline cartilage. The controlled release of morphogenic factors or bioactive molecules and the use of pluripotent mesenchymal progenitor cells opens new perspectives for the optimization of cartilage repair procedures.

Animals↗
PubMed2000

Segmental bone repair by tissue-engineered periosteal cell transplants with bioresorbable fleece and fibrin scaffolds in rabbits.

The biological bone healing depends on the presence of osteochondral progenitors and their ability for proliferation. Isolated periosteal cells were seeded into biodegradable PGLA polymer fleece or fibrin beads and cultivated for 14 days after prior monolayer culture. On 12 New Zealand white rabbits 8 mm metadiaphyseal ulna defects were created bilaterally and subsequently filled with cell-fibrin beads, with polymers seeded with cells compared to controls with fibrin beads and polymers alone and untreated defects. A semiquantitative grading score was applied for histomorphological and radiological analysis after 28 days. Histologically intense bone formation was observed in both experimental groups with cell transplants only. The histological and radiological scoring was superior for both experimental groups. Control groups revealed only poor healing indices and untreated defects did not heal. The highest histological score was noted in the group with polymer fleeces containing periosteal cells. Applying the radiographic score system we determined a significant difference between experimental groups and controls without cells. The radiographic and histological scores for both experimental groups containing periosteal cells differed not significantly. The results strongly encourage the approach of the transplantation of pluripotent mesenchymal cells within a suitable carrier structure for the reconstruction of critical size bone defects.

Animals↗
PubMed2000

Cultivation of porcine cells from the nucleus pulposus in a fibrin/hyaluronic acid matrix.

Use of multiplied viable cells from the nucleus pulposus in altered discs, following in vitro cultivation, may be a promising therapy for degenerative disc disease. Up till now, alginate has been used as a three-dimensional cell carrier to cultivate nucleus pulposus cells. However, the biocompatibility of the alginate, which depends on the composition and purity of alginate materials used, has not been considered for in vivo application so far. In this study, we cultured porcine cells from the nucleus pulposus in a mixture of fibrin and hyaluronic acid (HA). The DNA content and proteoglycan synthesis were compared to those measured in an alginate matrix. Although the increase in DNA content was 2.5-fold higher in the alginate culture after 3 weeks, the proteoglycan synthesis in relation to the DNA content was significantly higher in the fibrin/HA matrix. We found that the fibrin/hyaluronic acid matrix can be used as a substrate for in vitro cultivation.

Animals↗
PubMed2000

Tissue engineered cartilage repair using cryopreserved and noncryopreserved chondrocytes.

The objective of this study was to reconstruct full thickness cartilage defects in rabbit knees with in vitro engineered cartilage tissue based on noncryopreserved and cryopreserved chondrocytes in polymer fleece scaffolds. Osteochondral defects in rabbits were filled with polymer cylinders with noncryopreserved or cryopreserved allogeneic chondrocytes and compared with empty defects and defects filled with polymers alone. The defects were evaluated macroscopically and histologically 4 and 12 weeks after surgery. Transplant samples were graded using a semiquantitative score system. Successful healing was defined as complete integration of a hyalinelike and structurally intact cartilage into the defect and occurred in 71% of the group with noncryopreserved chondrocytes after 4 weeks and 100% of the rabbit knees after 12 weeks, whereas hyalinelike cartilage was seen in 71% of the group with cryopreserved chondrocytes after 4 weeks, and in 85% after 12 weeks. No newly formed cancellous bone was present in the subchondral bone. In the control groups, no cartilagelike tissue was seen. Transplantation of chondrocytes in polymer fleece constructs is a suitable approach for joint cartilage repair. Noncryopreserved chondrocytes are preferred to cryopreserved chondrocytes because of their regenerative potential. In vitro engineered cartilage offers broad opportunities for optimization of cartilage transplantation based on the controlled use of morphogenic and biologically active factors such as transforming growth factor-beta and bone morphogenetic proteins.

Animals↗
PubMed1999

Joint cartilage regeneration by tissue engineering.

The research field of tissue engineering combines cells biology, biomaterial science, and surgery. Major long-term goals are tissue and organ replacement therapies using the patients' own cells. Our work is focused on the treatment of severe joint defects and on plastic surgery using in vitro engineered cartilage tissues. The practical approaches in cartilage engineering face problems with three-dimensional cell distribution or cell immobilization raising biocompatibility problems. The tissue engineering of cartilage is based on combining biocompatible cell embedding substances such as fibrin, agarose, alginate, hyaluronic acid and fiber fleece scaffolds of poly alpha-hydroxy acids (PLLA/PGLA). Different technical approaches were established: a) three-dimensional in vitro cultures of chondrocytes for the development of vital tissue transplants and b) interacting three-dimensional cultures consisting of different cell populations, such as BMP-transfected mesenchymal cells. The preshaped artificial tissue constructs were cultured in perfusion chambers to maintain a stable diffusion of nutrients during the in vitro pre-formation step. Subsequently, pre-formed tissues were implanted into nude mice and into 4 mm articular joint defects of rabbits. Transplants were found to produce cartilage typic morphological patterns and matrix. 80% of the transplants remained stable in vivo. However, 20% of the tissues are resorbed or replaced by a fibrous tissue. These results demonstrate that current artificial cartilage transplants are already feasible for plastic reconstruction. The treatment of severe joint defects, however, faces additional problems which are addressed in ongoing studies: (a) the fixation of engineered cartilage in joints, (b) the protection against chronic inflammatory degradation, and (c) the required enormous mechanical stability.

Animals↗
PubMed1999

Bone engineering on the basis of periosteal cells cultured in polymer fleeces.

Large bone defects caused by severe trauma, infection or tumor resection are still a major challenge for orthopaedic surgery. The key concept for successful bone regeneration consists of combining the osteoinductive effect of osteogenic cells with a suitable carrier structure to promote osteoblastic differentiation and optimal matrix production. Therefore, periosteal cells cultured in polyglycolic-polylactid acid (PGLA) fleeces were investigated for their osteogenic differentiation and used to repair critical size bone defects in a rabbit model. Periosteal cells were isolated from New Zealand White rabbits and expanded in vitro. Osteogenic differentiation was investigated by analysis of alkaline phosphatase and osteocalcin production in vitro depending on culture conditions and passage number. Cells were seeded into PGLA fleeces. After further cultivation, tissue constructs were examined histologically and by immunohistochemistry for cell distribution and osteogenic differentiation. These constructs of defined size were used to repair critical size calvarial defects (group I) in rabbits compared to a defect repair with polymers only (group II) or to untreated defects (group III). Bone healing was evaluated after 4 weeks by radiodensitometry and a special histological scoring system. For early evaluation, radiodensitometry was not sensitive enough to detect differences in calcification. However, on histologic examination the group with cell/fleece constructs revealed intense formation of uncalcified bone. The mean defect closure of the experimental group I was 65%, compared to control groups II and III with 31% and 22%, respectively. The established methods of 3-D-cell culture and ex-vivo transplant assessment proved to be a valuable tool for quality assurance. The results demonstrate that the combination of periosteal cells and polymer fleeces is a tissue engineering approach, which may have clinical applications in various fields of reconstructive surgery.

Journal Article↗
PubMed1997

Development of in vitro model systems for destructive joint diseases: novel strategies for establishing inflammatory pannus.

OBJECTIVE: To establish a novel 3-dimensional (3-D) in vitro model for the investigation of destructive processes in rheumatoid arthritis (RA). METHODS: Two distinct culture systems were developed, consisting of RA synovial membrane and articular cartilage explants or interactive RA synovial cell/chondrocyte cultures embedded in 3-D fibrin matrices. The expression of proteolytic enzymes, chondrocyte matrix architecture, and matrix degradation parameters was analyzed by immunohistochemistry. RESULTS: Of 28 RA explant cultures, 16 displayed an invasion of synovial tissue into the cartilage explants, compared with 1 of 8 osteoarthritis explants. The expression of collagenase and vascular cell adhesion molecule 1 could be demonstrated at the cartilage-pannus junction. Of 20 interactive cell cultures, 18 revealed invasive behavior and remained vital for extended periods of time. CONCLUSION: The models presented allow us to study distinct aspects of destructive joint diseases under in vitro conditions that resemble human pathology. Moreover, our model is able to supplement animal experiments in basic research and drug testing.

Animals↗
PubMed1997

Artificial tissues in perfusion culture.

In the stagnant environment of traditional culture dishes it is difficult to generate long term experiments or artificial tissues from human cells. For this reason a perfusion culture system with a stable supply of nutrients was developed. Human chondrocytes were seeded three-dimensionally in resorbable polymer fleeces. The cell-polymer tissues were then mounted in newly developed containers (W.W. Minuth et al, Biotechniques, 1996) and continuously perfused by fresh medium for 40 days. Samples from the effluate were analyzed daily, and the pH of the medium and glucose concentration remained stable during this period. The lactid acid concentration increased from 0.17 mg/ml to 0.35 mg/ml, which was influenced by the degradation of the resorbable polymer fibers used as three dimensional support material for the cells. This perfusion system proved to be reliable especially in long term cultures. Any components in the culture medium of the cells could be monitored without disturbances as caused by manual medium replacement. These results suggest the described perfusion culture system to be a valuable and convenient tool for many applications in tissue engineering, especially in the generation of artificial connective tissue.

Adult↗
PubMed1996

[Tissue engineering of human cartilage tissue for reconstructive surgery using biocompatible resorbable fibrin gel and polymer carriers].

Current practical approaches in cartilage engineering still face problems with three dimensional cell distribution or require components for cell immobilization, raising biocompatibility problems. In this study, we present a new model using cells cross-linked by fibrin within biocompatible resorbable polymers. Both components have been in clinical use for a long time. Immunohistochemical procedures showed that this model provides optimal requirements for in vitro cartilage production. Immunochemically, cartilage-specific extracellular components such as proteoglycan, chondroitin sulfate and collagen II were characterized. Histomorphological methods showed a mechanically stable tissue compound that lasted for at least 5 weeks. This model may be the first to provide all biocompatible requirements for in vitro production of autologous cartilage transplants for reconstructive surgery.

Biocompatible Materials↗
PubMedDate not supplied

Joint cartilage repair with transplantation of embryonic chondrocytes embedded in collagen-fibrin matrices.

OBJECTIVE: The objective of this study was to assess the feasibility of transplanting embryonic chondrogenic cells within a collagen-fibrin substrate for the reconstitution of full-thickness cartilage defects in chicken knee joints. METHODS: Full-thickness cartilage defects were created mechanically on the weight-bearing surface of the tibial condyle in 45 adult chickens and subsequently filled with chondrocytes embedded in a chondrocyte-collagen-fibrin gel. The transplants were compared to untreated defects and collagen-fibrin transplants without cells. The results were analyzed using histochemical and morphometrical methods after 3, 12 and 24 weeks. A semiquantitative histological grading system was applied to evaluate the transplant integration and the newly formed cartilage architecture. RESULTS: Chondrocyte-gel grafts developed to hyaline-like cartilage without any granulation tissue in the interface after 3 weeks. After 12 weeks the defects in the experimental group were filled completely with hyaline cartilage. The defects in the control groups in all cases healed with fibrous repair tissue. CONCLUSION: Fibrin-collagen gel allowed stable graft fixation and provided an adequate microenvironment for embryonic chondrocytes to generate hyaline-like neocartilage in a full-thickness cartilage defect.

Animals↗