Maciej Patrzyk

In vivo investigation of the inflammatory response against allylamine plasma polymer coated titanium implants in a rat model

Titanium (Ti) is an established biomaterial for bone replacement. However, facilitation of osteoblast attachment by surface modification with chemical groups could improve the implant performance. Therefore, this study aimed to evaluate the effect of a plasma polymerized allylamine (PPAAm) layer on the local inflammation in a rat model. Three series (RM76AB, RM78AB, RM77AB) of PPAAm-treated Ti plates were prepared using different plasma conditions. Twelve male LEW.1A rats received one plate of each series and one uncoated control plate implanted into the back musculature. After 7, 14 and 56 days, four rats were euthanized to remove the implants with surrounding tissue. Total monocytes/macrophages, tissue macrophages, T-cells and MHC-class-II-positive cells were morphometrically counted. On day 14, the macrophage/monocyte number was significantly higher for the controls than for the PPAAm samples. On day 56, the RM76AB and RM78AB samples had significantly lower numbers than RM77AB and the controls. The same was found for the tissue macrophages. No change over time and no differences between the implants were found for the T-cells. For the number of MHC-class-II-positive cells, a significant decrease was found only for the RM78AB implants between day 14 and day 56. Physico-chemical analysis of the PPAAm implants revealed that the RM77AB implants had the lowest water absorption, the highest nitrogen loss and the lowest oxygen uptake after sonication. These results demonstrate that the PPAAm samples and the controls were comparable regarding local inflammation, and that different plasma conditions lead to variations in the material properties which influence the tissue reaction.

Digital image analysis for morphometric evaluation of tissue response after implanting alloplastic vascular prostheses.

The aim of this study was to examine the suitability of digital image analysis, using the KS400 software system, for the morphometric evaluation of the tissue response after prosthesis implantation in an animal model. Twenty-four female pigs aged 10 weeks were implanted with infrarenal Dacron(R) prostheses for 14, 21, 28, and 116 days. Following the explantation and investigation of the neointima region, the expression of beta-1-integrin, the proliferation rate by means of Ki-67 positive cells, and the intima thickness were evaluated as exemplary parameters of the tissue response after implantation. Frozen tissue sections were immunohistochemically stained and subsequently examined using computer-aided image analysis. A maximum expression of 32.9% was observed for beta-1-integrin 14 days after implantation, gradually declining over time to 9.8% after 116 days. The proliferation rate was found to be 19% on day 14, increasing to 39% on day 21 with a subsequent gradual decline to 5% after 116 days. The intima thickness increased from 189.9 microm on day 14 to 1228.0 microm on day 116. In conclusion, digital image analysis was found to be an efficient and reproducible method for the morphometric evaluation of a peri-prosthetic tissue response.

Single-port versus standard laparoscopic resection for a gastric benign tumor in gastroscopic-laparoscopic rendezvous procedures using a laser-supported diaphanoscopy.

In this study, the standard laparoscopic technique versus the single-port approach was evaluated for the excision of benign gastric tumors using tissue-sparing laser-supported diaphanoscopy for localization. The first group consisted of 10 patients suffering from benign gastric tumors treated by standard laparoscopic resection. The second group included 10 patients treated using the single-port technique. All procedures were successfully completed. Histopathologic examination confirmed 15 cases of gastrointestinal stromal tumor, 3 cases of lipoma, 1 case of leiomyoma, and 1 case of high-grade dysplasia. There was no statistically significant difference for the operation times between both groups. Comparison of the largest and smallest resection margins achieved using the standard laparoscopic technique and single-port techniques showed no statistically significant differences between the groups. During follow-up, all patients were evaluated using the total body image and cosmesis questionnaire. Although scores of all body-image functions were similar, independent of laparoscopic technique, scores of all cosmetic functions in patients operated using the single-port technique showed a statistically significant higher degree of satisfaction with the scar (P<0185). The postoperative pain scores evaluated by the visual analog scale score were not significantly different between 2 groups. The single-port technique was found to be a feasible option for the resection of submucosal or mucosal tumors. However, this method is not intended to replace standard laparoscopic resections.

Murine Distal Colostomy, A Novel Model of Diversion Colitis in C57BL/6 Mice

Diversion colitis (DC) is a frequent clinical condition occurring in patients with bowel segments excluded from the fecal stream as a result of a diverting enterostomy. The etiology of this disease remains ill-defined but appears to differ from that of classical inflammatory bowel diseases such as Crohns disease and ulcerative colitis. Research aimed to decipher the pathophysiological mechanisms leading to the development of this disease has been severely hampered by the lack of an appropriate murine model. This protocol generates a murine model of DC that facilitates the study of the immune systems role and its interaction with the microbiome in the development of DC. In this model using C57BL/6 animals, distal parts of the colon are excluded from the fecal stream by creating a distal colostomy, triggering the development of mild to moderate inflammation in the excluded bowel segments and reproducing the hallmark lesions of human DC with a moderate systemic inflammatory response. In contrast to the rat model, a large number of genetically-modified murine models on the C57BL/6 background are available. The combination of these animals with our model allows the potential roles of individual cytokines, chemokines, or receptors of bioactive molecules (e.g., interleukin (IL)-17; IL-10, chemokine CXCL13, chemokine receptors CXCR5 and CCR7, and the sphingosine-1-phosphate receptor 4) to be assessed in the pathogenesis of DC. The availability of congenic mouse strains on the C57BL/6 background largely facilitates transfer experiments to establish the roles of distinct cell types involved in the etiology of DC. Finally, the model offers the opportunity to assess the influences of local interventions (e.g., modification of the local microbiome or local anti-inflammatory therapy) on mucosal immunity in affected and non-affected bowel segments and the on systemic immune homeostasis.

A Cell-Adhesive Plasma Polymerized Allylamine Coating Reduces the In Vivo Inflammatory Response Induced by Ti6Al4V Modified with Plasma Immersion Ion Implantation of Copper

Copper (Cu) could be suitable to create anti-infective implants based on Titanium (Ti), for example by incorporating Cu into the implant surface using plasma immersion ion implantation (Cu-PIII). The cytotoxicity of Cu might be circumvented by an additional cell-adhesive plasma polymerized allylamine film (PPAAm). Thus, this study aimed to examine in vivo local inflammatory reactions for Ti6Al4V implants treated with Cu-PIII (Ti-Cu), alone or with an additional PPAAm film (Ti-Cu-PPAAm), compared to untreated implants (Ti). Successful Cu-PIII and PPAAm treatment was confirmed with X-ray Photoelectron Spectroscopy. Storage of Ti-Cu and Ti-Cu-PPAAm samples in double-distilled water for five days revealed a reduction of Cu release by PPAAm. Subsequently, Ti, Ti-Cu and Ti-Cu-PPAAm samples were simultaneously implanted into the neck musculature of 24 rats. After 7, 14 and 56 days, peri-implant tissue was retrieved from 8 rats/day for morphometric immunohistochemistry of different inflammatory cells. On day 56, Ti-Cu induced significantly stronger reactions compared to Ti (tissue macrophages, antigen-presenting cells, T lymphocytes) and to Ti-Cu-PPAAm (tissue macrophages, T lymphocytes, mast cells). The response for Ti-Cu-PPAAm was comparable with Ti. In conclusion, PPAAm reduced the inflammatory reactions caused by Cu-PIII. Combining both plasma processes could be useful to create antibacterial and tissue compatible Ti-based implants.

Retrieval of a self-expanding metal stent after migration and incorporation in the omental bursa, using a gastroscopic-transgastric laparoscopic rendezvous technique.

Endoscopic drainage is a widely used treatment for pancreatic pseudocysts. Drainage-related complications may be related directly to the procedure or may occur later as stents migrate or erode into adjacent structures. Migration of a self-expanding metal stent into peritoneal cavity and incorporation in the omental bursa is rare. When endoscopic retrieval fails a combined laparoscopic-endoscopic (rendezvous technique) approach offers an alternative to open surgery. We report a case of successful gastroscopic-transgastric laparoscopic removal of a stent that was dislocated into the omental bursa after a ΍ year observation period.

Time course of fibronectin in the peri-implant tissue and neointima formation after functional implantation of polyester-based vascular prostheses with different porosity in pigs

Intima hyperplasia, resulting from extracellular matrix (ECM) secretion, can lead to vascular prosthesis occlusion and is a major problem in vascular surgery. Fibronectin might contribute to ongoing ECM secretion. However, the exact role of fibronectin and its influence on neointima formation remains unclear. This study was aimed at investigating the time course of the fibronectin area fraction and neointima formation following the functional implantation of three different polyester vascular prostheses into pigs. The infrarenal aorta from 15 animals (n = 5/group) was replaced by prosthesis segments with low, medium and high primary porosity. After 7, 14, 21, 28 and 116 days, the prostheses were morphometrically examined. Overall, the fibronectin area fraction was inversely correlated with the neointima thickness, demonstrating high fibronectin levels in the early phase (days 7 and 14) and low levels in the later phase with almost complete neointima formation (days 21-116). Throughout the study, fibronectin levels were highest at the proximal anastomosis region. The low porosity prosthesis had the highest fibronectin area fraction and a delayed neointima formation in the middle phase (days 21 and 28) but the highest neointima lining on day 116. The results indicate a relationship between fibronectin and neointima formation with the prosthesis porosity, demonstrating the importance of the textile design for tissue reactions following implantation.

Differenzierung der humoralen Immunantwort gegen Bestandteile von Kollagen-imprägnierten Dacron-Gefäßprothesen im Tiermodell Schwein

Background/Aim: Recent studies have shown the induction of specific antibodies after repeated implantation of polymeric biomaterials such as Dacron vascular prostheses in rats and mice. The present study was aimed at further differentiating the humoral immune response against components of prostheses after single functional implantation of Dacron vascular prostheses in pigs. Methods: The infrarenal aortas of 22 female pigs weighing 24-29 kg were resected and replaced by a segment of a collagen-impregnated Dacron vascular prosthesis (Meadox hemashield, length 5 cm, diameter 0.8 cm). Serum samples were drawn at days 1 (day of implantation), 10,17,24,62,116. Detection of polymer antibodies was performed by modified enzyme immunoassay using the prosthesis as an antigenic target. Furthermore, antibodies against the coating substance bovine collagen and serum IgG content of samples were determined by ELISA. Results: A significant antibody formation against the polymer matrix was already determined at experimental day 10 (p<0.05 vs day 1). The highest antibody prevalences were obtained at days 10 and 17 with 40.9% (9/22) antibody-positive animals. Circulating polymer antibodies were detected in 36.4% (8/22) of pigs at day 62, whereas only 3/22 had polymer antibodies at day 116. The prevalence of antibodies against native bovine collagen varied between 40.9% (9/22 animals) at day 24 and 68.2% (15/22 animals) at experimental day 116. No correlation was found between polymer antibodies and collagen antibodies as well as time course of serum IgG concentration. Conclusion: IgG antibodies against the prosthesis matrix and the prosthesis impregnation were induced after single functional implantation of a Dacron vascular prosthesis in a pig animal model. The time course of antibody formation as well as antibody titers have shown a high variability in individual animals. The detection of specific antibodies against components of implants reflecting the individual inflammatory response might be a parameter of individual bio(in)compatibility and in appropriate vascular prosthesis selection.