Abstracts 4. Gemeinsamer Jahreskongress der ... - SWISS KNIFE

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Bern/CH, 4 Vchk, Inselspital, 3011 Bern/CH, 5 Institute of Clinical Pharmacology, University of
Bern, Bern/CH, 6 Vchk, Inselspital, Bern/CH, 7 Clinic of Visceral- and Transplant Surgery,
University Hospital of Berne, 3010 Berne/CH
Tumor monitoring in animal models by the tissue inhibitor of metalloproteinases (TIMP-1)
Objective: TIMP-1, a soluble 28kDa protein of the inhibitors of matrix metalloproteinases
(MMP’s) family, has been shown to have additional tumor promoting activity. High serum
levels of TIMP-1 in patients with colorectal cancer correlated with worse prognosis. This is why
we evaluated if TIMP-1 could be used to monitor tumor growth in animal models.
Methods: TIMP-1 levels of various colorectal cancer cell lines (SW620, CT26) have been
determined in vitro by ELISA and Western blot. Tissue from colorectal and hepato-cellular cancer
models (mice and rat) were tested for TIMP-1 expression by Imunohistochemistry (IHC),
PCR and Western blot analysis. Ultimately, serum levels of TIMP-1, as determined by ELISA
were compared with tumor size of sacrificed animals.
Results: Whole cell lysates and supernatant from colorectal cancer cell cultures (human: SW
620, mouse: CT26) showed high levels of TIMP-1, which correlated with anti-tumor treatment.
Tissue from a syngeneic orthotopic mouse model for peritoneal carcinosis showed treatment
dependent expression of TIMP-1 in IHC and Western blot. Accordingly, serum levels of TIMP-1
in these mice correlated with tumor size of treated and control mice (r=0.74 and 0.758,
Pearson). TIMP-1 serum levels of rats bearing Morris hepatoma liver tumors also correlated
with tumor size at time of scarification (r=0.774).
Conclusion: Serum levels of TIMP-1 may be used to monitor tumor growth and treatment
response repeatedly without the need to sacrifice the animals. This method would allow to
use orthotopic tumor models and reduce the amount of animals necessary to evaluate the
efficacy of novel anti-tumor treatments.
31.06
M. Cikirikcioglu 1 , Y.B. Cikirikcioglu 1 , J. Tille 2 , A. Kalangos 1 , B.H. Walpoth 1
1 Department of Cardiovascular Surgery, University Hospital of Geneva, 1211 Geneva/CH,
2 Department of Clinical Pathology, University Hospital of Geneva, 1211 Geneva/CH
Does size matter? Better endothelialisation in well matched ePTFE grafts
Objective: Intimal hyperplasia and endothelialisation correlate inversely with shear stress and
flow characteristics. Therefore, mismatch between native artery and graft diameter may
affect intimal hyperplasia formation and endothelial coverage. The aim of this study is to compare
mismatched (1 mm) and well matched (2mm) ePTFE grafts after implantation in the rat
abdominal aorta with regard to angiographic dimensions and morphologic changes.
Methods: In 16 male Sprague Dawley rats (415 ± 60 gr), 1 mm (n=8) and 2 mm ePTFE (n=8)
grafts were interposed in the infrarenal abdominal aorta. The proximal and distal anastomoses
were performed with 10/0 interrupted nylon sutures with an operative microscope.
Anastomosis quality was evaluated intra-operatively with a transit time flowmeter. Animals
were followed for 3 weeks and angiography was performed via right carotid artery before
sacrifice. We measured midgraft, proximal and distal aorta diameters using quantitative
abdominal aortography (QAA). Grafts were then harvested for computed morphometric analysis.
Statistics were performed using Mann Whitney U test.
Results: Intraoperative flow amounts were similar for two groups. After 3 weeks of implantation
patency rate was 87% and 100% for 1 mm and 2 mm ePTFE grafts, respectively. Intimal
hyperplasia was similar for both groups (11 ± 9 vs 10 ± 16 μm2/μm for 1 mm and 2 mm
grafts, respectively) but endothelial coverage was significantly better in well matched 2 mm
grafts (440 ± 233 vs 659 ± 239 μm for 1 mm and 2 mm grafts, respectively; p=0.008).
Conclusion: In well-matched grafts we find a significantly better endothelialisation. This may
influence long-term results despite early similar patency rates.
31.07
A. Demirag 1 , N. Guvener 2 , P. Morel 3 , S. Richter 4 , S. Deng 5 , C. Toso 6 , J. Philippe 4 , T. Berney 7 , J.
Vallee 8 , L. Bühler 6
1 Surgery&transplantation, YED TEPE UNIVERSITY HOSPITALS, 34752 ISTANBUL/TR, 2 Endocrinology
and Metabolism, Baskent University Hospital, ankara/TR, 3 Visceral/transplantation
Surgery, Geneva University Hospitals, Geneva 14/CH, 4 Internal Medicine, University of Geneva,
Geneva/CH, 5 Surgery, University of Pennsylvannia, Pennsylvannia/US, 6 Digestive Surgery and
Transplantation, University of Geneva, Geneva 14/CH, 7 Visceral/transplantation Surgery,
Geneva University Hospitals, 1211 Geneva/CH, 8 Radiology, University of Geneva, Geneva/CH
Long-term effects of intra-hepatic islet auto- and allografts on liver parenchyma
Objective: Liver is considered the optimal implantation site for islet grafts. Recent reports described
periportal steatosis by magnetic resonance (MRI) in recipients of functioning islet allografts.
No data exist on long-term effects of intra-hepatic islet auto- and allografts on liver
parenchyma and no clear explanation for this phenomenon is available. The aim of the present
study was to analyze liver parenchyma of patients previously transplanted with islet autoand
allografts.
Methods: Patients who underwent islet transplantation over a 12 years period were evaluated
for the study. They were divided as Group 1 (allograft) and Group 2 (autograft). Islet function
was assessed by daily insulin requirement, fasting and stimulated C-peptide, HbA1c at time
of imaging. All patients were investigated by abdominal ultrasound, MRI, liver function tests,
and lipid profile.
Results: In Gr.1, steatosis was observed on MRI in 3/16 patients, and in Gr.2 in 3/6 patients.
In Gr.1, patients with steatosis had higher basal (476vs.289 pmol/L, p85%), there was no
significant difference between patients with or without steatosis.
Conclusion: Hepatic steatosis can be associated with both islet auto- and allografts. In islet
allograft recipients, steatosis was correlated to better graft function, and may be induced by
a functional islet mass, i.e. paracrine effects of insulin released by transplanted islets on surrounding
liver parenchyma.
31.08
I. Inci 1 , W. Zhai 1 , S. Arni 2 , S. Hillinger 2 , W. Weder 2
1 Department of Thoracic Surgery, University of Zurich, 8091 Zurich/CH, 2 Department of
Thoracic Surgery, University of Zurich, Zurich/CH
N-Acetyl cysteine attenuates ischemia-reperfusion injury after lung transplantation
Objective: Early acute graft dysfunction continuous to be a problem after lung transplantation
resulting in significant postoperative morbidity and mortality. The purpose of this study was to
assess the protective effect of N-acetyl cysteine on post-transplant lung ischemia-reperfusion
injury.
Methods: Rat single-lung transplantation was performed in two (n=5) experimental groups
after 18 hours of cold (4 C) ischemia. Group I animals consisted the ischemic control group.
In group II, donor and recipient animals were treated with intraperitoneal injection of 150
mg/kg N-acetyl cysteine 15 minutes prior to harvest and reperfusion, respectively. After 2
hours of reperfusion, oxygenation was measured. Lung tissue was assessed for lipid peroxidation,
neutrophil infiltration and reduced glutathione level. Peak airway pressure (PawP)
was recorded throughout the reperfusion period.
Results: N-acetyl cysteine treated group showed significantly better oxygenation (184.5 ±
83.3 mmHg versus 67.3 ± 16.4 mmHg, p=0.016), reduced lipid peroxidation (7.34 ± 1.9
micromol/g versus 17.46 ± 10.6 micromol/g, p=0.016). Lung tissue reduced glutathione
levels in IC and NAC groups were 6.8±0.9 μM and 20.6±2.4 μM, respectively (p=0.004).
Peak airway pressures at the end of the reperfusion period was 14.4±1.6 cm H2O in NAC
group, and 19.2±2.2 cmH2O in IC group (p=0.008). Myeloperoxidase activity and wt to dry
weight ratio not differ between the groups.
Conclusion: In this model, exogenously administered N-acetyl cysteine effectively protected
lungs from reperfusion injury after prolonged ischemia.
31.09
D.J. Schaefer 1 , O. Scheufler 1 , C. Jaquiery 1 , D.J. Wendt 2 , A. Braccini 2 , P. Ingold 3 , J.A. Gasser 3 , M.
Jakob 4 , G. Pierer 1 , I. Martin 2 , M. Heberer 5
1 Reconstructive Surgery, University Hospital Basel, 4031 Basel/CH, 2 Surgical Research,
University Hospital Basel, 4031 Basel/CH, 3 Musculoskeletal Diseases, Novartis Institutes for
Biomedical Research, Basel/CH, 4 Orthopedic Surgery, University Hospital Basel, 4031 Basel/
CH, 5 Surgical Research and Hospital Management, University Hospital Basel, 4031 Basel/CH
Size limits in autologous cell-based ectopic prefabrication of engineered bone flaps in
rabbits
Objective: Flap prefabrication and bone tissue engineering concepts could be combined to
overcome limited availability and donor site morbidity of autologous bone flaps. In this study,
we aimed at determining the depth of tissue ingrowth and bone tissue formation within an
ectopic engineered bone flap model in rabbits.
Methods: Autologous bone marrow stromal cells (BMSC) from 12 New Zealand White rabbits
were expanded and uniformly seeded into two porous hydroxyapatite scaffolds (55 mio cells
per 15 mm diameter, 30 mm height cylinder) using a perfusion bioreactor. One cell-scaffold
construct was wrapped in a panniculus carnosus flap and covered by a semipermeable
membrane (vascularized condition), whereas the second was only covered by the membrane
and inserted under the contralateral panniculus carnosus, as control (non-vascularized
condition). Constructs were explanted after 12 weeks and assessed by MRI, μCT and histology.
Results: No connective or bone tissue formation were detected under non-vascularized conditions.
Under vascularized conditions, constructs were filled by vascularized connective tissue
in the outer 4.2 ± 0.3 mm and contained bone tissue in the outer 2.5 ± 0.3 mm, resulting
in significant differences in all histomorphometric parameters assessed.
Conclusion: A panniculus carnosus flap supported ectopic prefabrication of large engineered
bone flaps in rabbits. The finding that bone tissue was restricted to the outer region of the flaps
could be explained by insufficient vascularization of the central core of the constructs upon
implantation and prompts for the development of strategies to improve vessel ingrowth from
the flap.
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32.01
D. Schmidt 1 , A. Mol 2 , C. Breymann 3 , B. Odermatt 4 , M. Gössi 5 , R. Prêtre 6 , M. Genoni 7 , G. Zund 8 ,
S.P. Hoerstrup 8
1 Klinik für Herz-und Gefässchirurgie, UniversiätsSpital Zürich, 8091 Zürich/CH, 2 Department of
Biomedical Engineering, Eindhoven University of Technology, The Netherlands, Eindhoven/NL,
3 Department of Gynaecology and Obstetrics, University Hospital, Zurich, Switzerland, 8091
Zürich/CH, 4 Institute for Clinical Pathology, UniversiätsSpital Zürich, 8091 Zurich/CH, 5 Institute
of Polymers, ETH, 8091 Zürich/CH, 6 Congenital Cardiovascular Surgery, University Children's
Hospital Zürich, Zürich/CH, 7 Herz Chirurgie, Stadtspital Triemli, 8063 Zürich/CH, 8 Klinik für
Herz-und Gefässchirurgie, UniversiätsSpital Zürich, Zürich/CH
A novel concept: engineering of living autologous pediatric cardiovascular tissue replacements
using prenatal progenitors
Objective: Here, a novel concept using human prenatal progenitor cells for cardiovascular
engineering is presented, in order to generate living autologous implants with the potential of
growth, remodeling and regeneration for the repair of congenital malformation ready to use
at birth.
Methods: Prenatal progenitor cells were isolated from either placenta, Wharton’s jelly or cord
blood. After differentiation and characterization cells were expanded in vitro. For fabrication of
cardiovascular tissues, biodegradable scaffolds (PGA/P4HB) were seeded with either placenta-derived
cells or with Wharton’s Jelly-derived cells. Constructs were implanted in an in
vitro perfusion-strain bioreactor and exposed to biochemical and/or mechanical stimulation.
After 21d, the surfaces of constructs were endothelialized with blood-derived EPC and cultured
for additional 5d. Tissue formation was analyzed by histology, immunohistochemistry,
and scanning electron microscopy. Extracellular matrix elements and cell amount were quantified
by biochemistry.
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