The influence of a multifunctional, polymeric biomaterial on the concentration of acute phase proteins in an animal model.

The concentrations of the acute phase proteins alpha1-Acid Glycoprotein (AAG) and haptoglobin were determined in Sprague-Dawley-rats after implantation of a novel biodegradable multifunctional polymeric biomaterial for the reconstruction of a gastric wall defect (polymer group; n=42). For comparison, the concentrations of AAG and haptoglobin were measured as well after primary wound closure of the gastric wall defect without biomaterial implantation (control group; n=21) and in rats without any surgical procedure (baseline group; n=21). The implantation periods were 1 week, 4 weeks and 6 months. The concentrations of AAG and haptoglobin were measured by an ELISA assay. Gastrointestinal complications like fistula, perforation or peritonitis did not occur in any of the animals. No statistically significant differences in the concentrations of AAG and haptoglobin were detected between the polymer and the control group. An adequate mechanical stability of the polymeric biomaterial was detectable under the extreme pathophysiological conditions of the stomach milieu. In further examinations the correlation between the intraperitoneal cytokine levels of the animals and the following systemic inflammatory markers should be analysed. Further investigations are needed to analyse the mechanisms of the tissue integration of a biomaterial as well as the process of the tissue remodeling and the influence of the immune system on these mechanisms. The knowledge of these processes is necessary to adapt the multifunctional biomaterial and prepare it thus for the use and implantation in different body locations and to develop novel therapeutical options in medicine.

[First results of the investigation of the stability and tissue integration of a degradable, elastomeric copolymer in an animal model]. / Erste Ergebnisse zur Untersuchung der Stabilität und Gewebeintegration eines abbaubaren, elastischen Copolymers im Tiermodell.

The stability and tight integration into adjacent tissue of a novel, degradable, elastic copolymer were examined in an animal model. The biomaterial was used for the reconstruction of a gastric wall defect in Sprague-Dawley rats (n=42) to test the polymeric material under the extreme chemical, enzymatical and mechanical conditions of the stomach. In the control group (n=21) the same defect of the gastric wall was primarily closed without biomaterial implantation. In the baseline group (n=21) the animals were kept under standard conditions without any surgical procedure. The implantation periods were 1 week, 4 weeks and 6 months. The animals' weight was determined preoperatively and before explantation. After explantation, air was pumped into the stomach and the pressure was measured by using a pressure-gauge in order to test whether the surgically produced union of the stomach wall and the polymer patch was gas-tight. After 1 week of implantation time a statistically significant increase of the body weight of the animals was found only in the baseline group. Four weeks and 6 months after the abdominal surgical procedure, a statistically significant increase of the animals' weight was found in the implantation group, the control and the baseline group. Gastrointestinal complications like fistula, perforation or peritonitis did not occur in any of the animals. The measurement of the stomach pressure after maximal gas insufflation did not show significant differences between the implantation group, the control and the baseline group in any of the time periods investigated. Despite very high strains of the gastric wall, no gas leakage was detected. There was a tight connection between the polymer and the adjacent stomach wall in all animals investigated. An adequate mechanical stability of the biomaterial was detectable under the extreme pathophysiological conditions of the stomach milieu. A fast and unfavourable degradation of the degradable polymer was not found in any of the animals. Further investigations are needed to analyse the mechanisms of the tissue integration of the biomaterial as well as the degradation kinetic of the polymer and the process of the tissue remodeling. The knowledge of these processes is necessary to adapt the novel biomaterial and thus prepare it for the use and implantation in different body locations and to develop novel therapeutical options in medicine.