Helga Bergmeister

Repair of local bone erosions and reversal of systemic bone loss upon therapy with anti-tumor necrosis factor in combination with osteoprotegerin or parathyroid hormone in tumor necrosis factor-mediated arthritis.

Local bone erosion and systemic bone loss are hallmarks of rheumatoid arthritis and cause progressive disability. Tumor necrosis factor (TNF) is a key mediator of arthritis and acts catabolically on bone by stimulating bone resorption and inhibiting bone formation. We hypothesized that the concerted action of anti-TNF, which reduces inflammation and parathyroid hormone (PTH), which stimulates bone formation, or osteoprotegerin (OPG), which blocks bone resorption and could lead to repair of local bone erosions and reversal of systemic bone loss. To test this, human TNF-transgenic mice with established erosive arthritis and systemic bone loss were treated with PTH, OPG, and anti-TNF, alone or in combination. Local bone erosions almost fully regressed, on combined treatment with anti-TNF and PTH and/or OPG, suggesting repair of inflammatory skeletal lesions. In contrast, OPG and anti-TNF alone led to arrest of bone erosions but did not achieve repair. Treatment with PTH alone had no influence on the progression of bone erosions. Local bone erosions all showed signs of new bone formation such as the presence of osteoblasts, osteoid formation, and mineralization. Furthermore, systemic bone loss was completely reversed on combined treatment and this effect was mediated by osteoblast stimulation and osteoclast blockade. In summary, we conclude that local joint destruction and systemic inflammatory bone loss because of TNF can regress and that repair requires a combined approach by reducing inflammation, blocking bone resorption, or stimulating bone formation.

Biocompatibility and Performance of the Wallstent and Several Covered Stents in a Sheep Iliac Artery Model

PURPOSE To compare the biocompatibility and performance of various stent-grafts to those of a bare stent in an ovine model with a subchronic (3 months) endpoint. MATERIALS AND METHODS Three different types of stent-grafts (ePTFE/nitinol, n = 8; polyester/nitinol, n = 8; and polycarbonate urethane/cobalt-alloy, n = 8) and a bare stent as a control (Ni-Co-Ti-steel-alloy, n = 8) were implanted in the iliac arteries in eight female sheep. One type of each stent-graft was implanted per animal, two implants at each side. The implantation sites for each type varied from animal to animal. Angiographic control and intravascular ultrasound (IVUS) imaging were performed before and after implantation, after 2 months, and before explantation at 3 months and were used to characterize patency and to assess intimal hyperplasia. After 3 months, the implants were retrieved and subjected to histologic evaluation (after methacrylate embedding, cutting, and histologic staining) to characterize the biologic response. RESULTS Implantation was technically successful in all procedures. At 2 and 3 months after implantation, all segments in which stents had been implanted were patent. Marked neointima formation was found in the polyester-covered stent-graft that showed significant luminal narrowing of 50%, compared to the ePTFE-covered (24%) and polycarbonate urethane-covered endoprostheses (22%), as well as the bare stent (Wallstent; 9%; P < .001). A minimal inflammatory vessel wall reaction was demonstrated for the polyester-covered and ePTFE-covered endoprostheses; the polycarbonate urethane-covered stent-grafts response was demonstrable but not significantly different from that of the Wallstent. At 3 months, the ePTFE-covered stent-graft showed incomplete (>90%) endothelial coverage; in the other endoprostheses, complete but partially immature endothelialization was found. CONCLUSION All stent-grafts induced an inflammatory vessel wall reaction with neointimal hyperplasia. The polyester-covered endoprosthesis caused a marked reaction with 50% luminal stenosis. Endothelialization was retarded with the ePTFE-covered stent-graft. The bare stent performed best in regard to neointimal formation and caused the least inflammatory response.

Cell therapy using microencapsulated 293 cells transfected with a gene construct expressing CYP2B1, an ifosfamide converting enzyme, instilled intra-arterially in patients with advanced-stage pancreatic carcinoma: a phase I/II study.

Matthias Lohr (principal investigator) · Zoltan Tibor Bago · Helga Bergmeister · Manfred Ceijna · Mathias Freund · Wolfgang Gelbmann · Walter H. Gunzburg · Ralf Jesnowski · Johannes Hain · Karlheinz Hauenstein Wolfgang Henninger · Anne Hoffmeyer · Peter Karle · Jens-Christian Kroger · Gunther Kundt · Stefan Liebe Udo Losert · Petra Muller · Alexander Probst · Katrin Puschel · Matthias Renner · Renate Renz · Robert Saller Brian Salmons · Maximilian Schuh · Ilse Schwendenwein · Kerstin von Rombs · Thomas Wagner · Ingrid Walter (coinvestigators)

Intraarterial instillation of microencapsulated cells in the pancreatic arteries in pig.

JENS C. KROGER,a,f HELGA BERGMEISTER,b ANNE HOFFMEYER,c,d MANFRED CEIJNA,b PETER KARLE,d,e ROBERT SALLER,d ILSE SCHWENDENWEIN,b KERSTIN VON ROMBS,d STEFAN LIEBE,c WALTER H. GUNZBURG,e BRIAN SALMONS,d KARLHEINZ HAUENSTEIN,a UDO LOSERT,b AND MATTHIAS LOHRc aDepartment of Diagnostic and Interventional Radiology, University of Rostock, Germany bCenter for Biomedical Research, General Hospital, University of Vienna, Austria cDepartment of Medicine, University of Rostock, Germany dBavarian Nordic Research Institute, Munich, Germany eInstitute of Virology, University of Veterinary Sciences, Vienna, Austria

Endothelialization of biosynthetic vascular prostheses after laser perforation

OBJECTIVE This study was undertaken to investigate the feasibility of transmural capillary ingrowth into the inner surface of biosynthetic vascular prostheses (Omniflow, BioNova, Melbourne, Australia) through perforations created by an excimer laser, thus inducing an endothelial cell coverage. METHOD Biosynthetic vascular prostheses (Omniflow, 10 cm length, 6 mm diameter) were perforated with an excimer laser (diameter of the holes 50 to 100 microm, distance 4 mm) and implanted into the carotid arteries of eight sheep. They were compared to untreated Omniflow prostheses implanted at the contralateral side. Three months after implantation the prostheses were explanted and evaluated by gross morphology, histologic examination, scanning electron microscopy, and immunohistochemical staining for factor VIII to identify endothelial cells. RESULTS All grafts remained patent. Gross morphologic examination revealed no significant difference in the thrombus-free surface between perforated and untreated prostheses. However, scanning electron microscopy showed endothelial cells in the midgraft portion of all perforated prostheses, whereas collagen fibers, fibrin meshwork, and activated platelets formed the inner layer in six of eight untreated Omniflow prostheses. Transmural capillary ingrowth in the laser group was verified by positive factor VIII staining for endothelial cells in the laser channels. CONCLUSION Spontaneous endothelialization of biosynthetic vascular prostheses can be achieved by transmural capillary ingrowth through perforations in the wall of the prostheses in an experimental sheep model.

Intra-arterial instillation of microencapsulated, ifosfamide-activating cells in the pig pancreas for chemotherapeutic targeting

Background: The therapeutic efficacy of intratumoral instillation of genetically engineered, CYP2B1-expressing, microencapsulated cells in combination with ifosfamide had been previously demonstrated in xenografted human pancreatic ductal carcinomas [Gene Ther 1998;5:1070–1078]. Prior to a clinical study, the feasibility of an intra-arterial application of microencapsulated cells to the pancreas and its consequences to the organ had to be evaluated. Material and Methods: Microencapsulated, CYP2B1-producing cells were instilled both in vivo (transfemoral angiographical access) and in vitro (perfusion model) in the splenic lobe of the pig pancreas. In vivo, animals were monitored clinically for 7 days, then treated with ifosfamide and sacrificed. In vitro, ifosfamide was administered intra-arterially. Results: In all animals, 100 microcapsules could be instilled safely via the femoral route without clinical, biochemical or histological signs of pancreatitis. Histological examination revealed partial obstruction of small arteries by the capsules, without causing any parenchymal damage. In vitro, instillation reduced blood flow by half. Ifosfamide, also in combination with the capsules, did not add any damage to the pancreas. Conclusion: Intra-arterial instillation of microencapsulated cells to the pig pancreas is feasible and safe. Neither pancreatitis, foreign body reactions nor circulatory disturbances were observed. Clinical application of this genetically enhanced chemotherapeutic method seems possible.

Zoledronic acid protects from local and systemic bone loss in tumor necrosis factor-mediated arthritis

Increased osteoclast activity is a key factor for bone loss in rheumatoid arthritis (RA). This suggests that osteoclast-targeted therapies could effectively prevent skeletal damage in RA. Zoledronic acid (ZA) is one of the most potent agents to block osteoclast function. We therefore investigated whether ZA can inhibit inflammatory bone loss. Human tumor necrosis factor transgenic (hTNFtg) mice, which develop severe destructive arthritis as well as osteoporosis, were treated with PBS, single or repeated doses of ZA, calcitonin or anti-tumor necrosis factor at the onset of arthritis. Synovial inflammation was not affected by ZA. In contrast, bone erosion was retarded by single administration (-60%) and almost completely blocked by repeated administration (-95%) of ZA. Cartilage damage was partly inhibited (-40%), and synovial osteoclast counts were significantly reduced upon ZA treatment. Systemic bone mass dramatically increased in hTNFtg mice upon ZA administration, which was due to an increase of trabecular number and connectivity. In addition, bone resorption parameters were significantly lowered after ZA. Calcitonin had no effect on synovial inflammation, bone erosions, cartilage damage or systemic bone mass. Anti-tumor necrosis factor entirely blocked synovial inflammation, bone erosion, synovial osteoclast formation and cartilage damage, but had only minor effects on systemic bone mass. ZA appears as an effective tool to protect bone from arthritic damage. In addition to antiinflammatory drug therapy, modern bisphosphonates are promising candidates to maintain joint integrity and to reverse systemic bone loss in arthritis.

Isolated and combined inhibition of TNF-, IL-1 and RANKL-pathways in TNF-induced arthritis: effects on synovial inflammation, bone erosion and cartilage destruction

To investigate the efficacy of isolated and combined blockade of TNF-, IL-1- and RANKL-pathways on synovial inflammation, bone erosion and cartilage destruction in a TNF-driven arthritis model, human TNF transgenic (hTNFtg) mice were treated with anti-TNF (infliximab), IL-1 receptor antagonist (IL-1Ra) or osteoprotegerin (OPG). In addition, each of three possible double combination therapies and a triple combination therapy was applied. Therapy was followed by histological assessment of synovial inflammation, bone erosion and cartilage damage. Synovial inflammation was inhibited by anti-TNF (-51%), but not IL-1Ra or OPG monotherapy. Combinations of anti-TNF with IL-1Ra (-91%) or OPG (-81%) were additive and almost completely blocked inflammation. Bone erosion was effectively blocked by anti-TNF (-79%) and also by OPG (-60%), but not by IL-1Ra monotherapy. Combination of anti-TNF and IL-1Ra, however, completely blocked bone erosion (-98%). The effects on inhibition of bone erosion were accompanied by reduction of osteoclast numbers within synovial tissue. Cartilage destruction was inhibited by anti-TNF (-43%), weakly, but not significantly by IL-1Ra, and not at all by OPG monotherapy. Combination of anti-TNF with IL-1Ra was the most effective double combination therapy in preventing cartilage destruction (-80%). In all analyses, a triple combination of anti-TNF, IL-1Ra and OPG was not superior to double combination therapy with anti-TNF and IL-1Ra. Articular changes caused by chronic TNF overexpression are not completely blockable by monotherapies, which target TNF, IL-1 or RANKL. However, combined approaches that reduce TNF load and block IL-1 or RANKL as downstream mediators of TNF can lead to a complete remission. Differences in their efficacy to block synovial inflammation, bone erosion and cartilage destruction further strengthen the rationale for combined blockade of more than one proinflammatory pathway.