Bo Risberg

Engineering microporosity in bacterial cellulose scaffolds.

The scaffold is an essential component in tissue engineering. A novel method to prepare three‐dimensional (3D) nanofibril network scaffolds with controlled microporosity has been developed. By placing paraffin wax and starch particles of various sizes in a growing culture of Acetobacter xylinum, bacterial cellulose scaffolds of different morphologies and interconnectivity were prepared. Paraffin particles were incorporated throughout the scaffold, while starch particles were found only in the outermost area of the resulting scaffold. The porogens were successfully removed after culture with bacteria and no residues were detected with electron spectroscopy for chemical analysis (ESCA) or Fourier transform infra‐red spectroscopy (FT–IR). Resulting scaffolds were seeded with smooth muscle cells (SMCs) and investigated using histology and organ bath techniques. SMC were selected as the cell type since the main purpose of the resulting scaffolds is for tissue engineered blood vessels. SMCs attached to and proliferated on and partly into the scaffolds. Copyright

Co‐culture of endothelial cells and smooth muscle cells affects gene expression of angiogenic factors

Endothelial cells (EC) are in contact with the underlying smooth muscle cells (SMC). The interactions between EC and SMC in the vessel wall are considered to be involved in the control of growth and function of blood vessels. A co‐culture system of EC and SMC and a method for separation of these cells was developed in order to investigate whether the presence of physical contact between EC and SMC affected the gene expression of angiogenic factors. Human EC and SMC were prepared from the great saphenous veins. Autologous EC were added on top of the confluent layer of SMC. After 72 h in co‐culture, the EC were magnetically separated from SMC with the use of superparamagnetic beads. RT‐PCR products for bFGF, bFGFR, VEGF, PDGF‐AA, PDGF‐BB, TGF‐β, and β‐actin were analyzed to study the mRNA expressions. The protein level of selected factors was studied by ELISA technique. In co‐cultured SMC there was a statistically significant higher gene expression of VEGF, PDGF‐AA, PDGF‐BB, and TGF‐β and significant lower gene expression of bFGF and its receptor than in single cultured SMC. The protein level of PDGF‐BB and TGF‐β was also significantly higher in co‐cultured SMC. In co‐cultured EC there were no significant differences in gene expression of PDGF‐AA, PDGF‐BB, and TGF‐β compared with single cultured EC. The gene expression and protein synthesis of VEGF was significantly higher in co‐cultured EC. The findings from the present study suggest that cell‐cell interactions of EC and SMC affect the gene and protein expression of angiogenic factors.

Experimental Models for Quantitative Studies on Adhesion Formation in Rats and Rabbits

Postoperative formation of adhesions is a common complication in abdominal surgery. The aim of the present study was to develop standardized experimental models for quantitative studies of the formation of adhesions in rats and rabbits. In rats the suturing of a peritoneal wound increased adhesion formation significantly compared to leaving it open, 77.9 +/- 4.8 and 5.3 +/- 2.8%, respectively (p < 0.001). The suturing technique, when comparing the interrupted and continuous method after 1 week, had no influence, 84.5 +/- 6.3% and 73.1 +/- 11.2%, respectively (p > 0.05). Different types of trauma resulted in differences in adhesion formation to noninjured parts in the abdominal cavity, adhesions in 17.5 and 2.5% of the animals, respectively (p < 0.05). In rabbits adhesions formed more frequently (p < 0.001) to visceral peritoneum (59.3 +/- 3.7%) than to the parietal one (22.3 +/- 1.6%) indicating a different propensity of tissues to have adhesions. These models enable detailed quantitative studies on experimental formation of adhesions.

A comparison of the Nottingham Health Profile and Short Form 36 Health Survey in patients with chronic lower limb ischaemia in a longitudinal perspective

BackgroundDifferent generic quality of life instruments such as the Nottingham Health Profile (NHP) and the Short Form 36 Health Survey (SF-36) have revealed conflicting results in patients with chronic lower limb ischaemia in psychometric attributes in short-term evaluations. The aim of this study was to compare the NHP and the SF-36 regarding internal consistency reliability, validity, responsiveness and suitability as outcome measures in patients with lower limb ischaemia in a longitudinal perspective.Methods48 patients with intermittent claudication and 42 with critical ischaemia were included. Assessment was made before and one year after revascularization using comparable domains of the NHP and the SF-36 questionnaires.ResultsThe SF-36 was less skewed and more homogeneous than the NHP. There was an average convergent validity in three of the five comparable domains one year postoperatively. The SF-36 showed a higher internal consistency except for social functioning one-year postoperatively and was more responsive in detecting changes over time in patients with intermittent claudication. The NHP was more sensitive in discriminating among levels of ischaemia regarding pain and more able to detect changes in the critical ischaemia group.ConclusionBoth SF-36 and NHP have acceptable degrees of reliability for group-level comparisons, convergent and construct validity one year postoperatively. Nevertheless, the SF-36 has superior psychometric properties and was more suitable in patients with intermittent claudication. The NHP however, discriminated better among severity of ischaemia and was more responsive in patients with critical ischaemia.

Aneurysm Sac Hygroma: A Cause of Endotension

Purpose: To describe a new pathophysiological mechanism for endotension. Case Reports: Four patients developed aneurysm sac expansion after repair of abdominal aortic aneurysms, one with a conventional polytetrafluoroethylene (PTFE) graft and the others with a variety of commercially made endografts (2 PTFE, 1 Dacron). Pressures within the sacs were nonpulsatile and approximately half the systemic blood pressure. Attenuation on computed tomography (CT) was significantly less in the sac than in the graft in 3 of the patients. A clear, highly viscous fluid was aspirated from all 4 sacs, supporting the diagnosis of aneurysm sac hygroma. Prominent local hyperfibrinolysis in the sac was combined with signs of local coagulation activation. Conclusions: A new mechanism for continued sac expansion based on aneurysm sac hygroma is proposed. Measurement of attenuation may be of diagnostic value. It is further proposed that local hyperfibrinolysis/coagulation may promote rebleeding, liquefaction, and continued expansion analogous to the chronic subdural hematoma.

Postoperative fever, bowel ischaemia and cytokine response to abdominal aortic aneurysm repair — a comparison between endovascular and open surgery

OBJECTIVES To study bowel ischaemia in transfemorally placed endoluminal grafting (TPEG) for abdominal aortic aneurysms, and any relation to cytokine response or postoperative fever. DESIGN Prospective not randomised. University hospital setting. MATERIAL Fourteen cases of conventional surgery and 23 cases of endovascular technique for infrarenal abdominal aortic aneurysm repair. METHODS Tonometry was used for sigmoid colon pH, and ELISAs for serum IL-6. RESULTS Mucosal pH in the sigmoid colon fell significantly during clamping and reperfusion in both groups. Lowest measured sigmoid colon pH was 7.10 in the open group, compared to 7.22 in the TPEG group (p < 0.05). The IL-6 levels in serum peaked after 4 h of reperfusion; 249 pg/ml in the open group, compared to 89 pg/ml in the TPEG group (p < 0.05). High levels of IL-6 in the postoperative period and persisting low sigmoidal pH were associated with serious complications. Postoperative temperature did not differ significantly between the groups, and no significant correlation could be found with sigmoid colon pH or IL-6 levels. CONCLUSIONS The less pronounced perioperative bowel ischaemia in TPEG patients indicates an advantage of the TPEG technique. Splanchnic ischaemia was not related to postoperative fever, nor the IL-6 or TNF response.

Endograft therapy for diseases of the descending thoracic aorta: results in 43 high-risk patients.

Purpose: To report an initial experience with endovascular stent-graft implantation for diseases of the descending thoracic aorta in high-risk patients. Methods: Forty-three patients (28 men; mean age 67 years, range 17–82) with 16 descending thoracic aortic dissections, 14 aneurysms, 7 contained ruptures, 3 mycotic aneurysms, 2 posttraumatic pseudoaneurysms, and an aneurysm of an anomalous right subclavian artery were treated between June 1999 and July 2001. Twenty-three (53%) patients were treated emergently. Results: There were no conversions to open repair, but 3 (7%) patients died during the first 30 days (pneumonia, multiorgan failure, and acute bowel ischemia). Thirteen (30%) patients suffered 18 major complications (8 strokes, paraplegia in 3, respiratory insufficiency in 6, and 1 renal failure). Of 7 (16%) endoleaks detected in the early postoperative period, 3 required additional stents, while the other 4 were treated conservatively. Follow-up, which averaged 19 ± 6 months (median: 13; range 0–34), was 100% complete. Five (12%) patients died: 3 of aortic rupture at 34, 47, and 139 days, respectively, and 2 from heart failure at 3 and 15 months, respectively. No late migration or endoleaks have been detected in the remaining 35 patients; however, 1 (2%) patient showed progressive aortic dissection proximal to the stent-graft. In all other cases, the size of the aneurysm or the false lumen was unchanged or diminished. Conclusions: Treatment of descending thoracic aortic diseases with an endovascular approach has acceptable early mortality and morbidity in high-risk patients. In selected cases, stent-grafts may afford the best therapy.

Characterization and fibrinolytic properties of mesothelial cells isolated from peritoneal lavage

Human peritoneal mesothelial cells were harvested from patients undergoing open or laparoscopic surgery for non-septic conditions using three different approaches: (1) from a peritoneal biopsy, (2) from peritoneal fluid, and (3) from lavage fluid collected from peritoneal cavity. When these different methods were compared, cells derived from peritoneal fluid or lavage were more likely to result in established cultures than those obtained from biopsies. The cells displayed morphological, immunohistochemical and ultrastructural characteristics of mesothelial cells. The cultured mesothelial cells produced tissue type plasminogen activator (t-PA), urokinase plasminogen activator (uPA), and plasminogen activator inhibitor type-1 and type-2 (PAI-1 and PAI-2) during unstimulated conditions. Treatment with the proinflammatory mediators LPS and TNF-alpha resulted in an overall decreased fibrinolytic capacity with a decrease in the release of t-PA and an increase in plasminogen activator inhibitors PAI-1 and PAI-2. TNF-alpha had a more profound effect than LPS, especially on the release of t-PA. This may be an important mechanism by which inflammatory mediators disrupt the fibrin degradation. In conclusion, peritoneal lavage is a convenient and reproducible source of mesothelial cells for culture.

Prospective Randomized Study Comparing Ultrasound-Guided Thrombin Injection to Compression in the Treatment of Femoral Pseudoaneurysms

Purpose: To compare in a randomized prospective study the treatment of femoral pseudoaneurysms with ultrasound-guided thrombin injection versus ultrasound-guided compression. Methods: Thirty consecutive patients (22 men; mean age 67±8 years, range 53–82) with iatrogenic femoral pseudoaneurysms were randomized to treatment with either ultrasound-guided compression (n=15) or injection of bovine thrombin (n = 15). The primary outcome measure was thrombosis of the pseudoaneurysm within 24 hours. Secondary outcome measures were complications and hospitalization time (LOS). Results: Thrombosis within 24 hours was achieved in 15 (100%) patients given thrombin versus 2 (13%) in the compression group (p<0.001). Of 13 pseudoaneurysms failing the initial compression treatment, 7 were retreated, 4 successfully. Thus, only 6 (40%) lesions were thrombosed within 48 hours after 1 or 2 compression sessions. The other 9 cases were successfully treated with thrombin injection. LOS was 2.8±1.5 days and 3.5±2.4 days in the thrombin and compression groups, respectively (p>0.05). No complications were noted in either group. Conclusions: Ultrasound-guided thrombin injection induces a fast, effective, and safe thrombosis of postcatheterization pseudoaneurysms. The technique is clearly superior to compression treatment and is recommended as the therapy of choice.

Preserved Pelvic Circulation after Stent-Graft Treatment of Complex Aortoiliac Artery Aneurysms: A New Approach

Purpose: To describe an endovascular technique that allows stent-graft treatment of aortoiliac aneurysmal disease affecting both common iliac arteries (CIA), with maintenance of pelvic circulation on one side. Technique: For patients with aortoiliac aneurysms, both common femoral arteries (CFA) were surgically exposed. One internal iliac artery (IIA) was initially embolized with coils. A bifurcated stent-graft main body was deployed with the proximal end just below the renal arteries. On the ipsilateral side, the stent-graft limb was extended 3 cm beyond the orifice of the embolized IIA into the external iliac artery (EIA) using stent-graft limb extenders. On the contralateral side, the stent-graft limb was deployed so that the distal end was 10 to 15 mm proximal to the patent IIA orifice. Via a left brachial artery access, the IIA was catheterized, and stent-grafts were deployed from the distal end of the contralateral AAA stent-graft limb into the IIA. A femorofemoral crossover graft provided circulation to the leg ipsilateral to the IIA stent-graft, and the EIA on the same side was ligated. The technique can also be modified to treat isolated bilateral CIA aneurysms. Conclusions: By extending the distal aspect of the stent-graft into an IIA, bilateral CIA aneurysms can be excluded while preserving pelvic circulation on one side.