Comparative Study of Bovine Pericardium and Gore-Tex in Tissual Interaction with Wistar Rats Diaphragm

Introduction: Simple suture isn’t always possible in large congenital diaphragmatic hernia (cdh) defects. Synthetic materials are used for correction such as Silastic&reg, Gore-Tex&reg (GT), Teflon&reg or biological, such as autologous muscle patches. It was shown that bovine pericardium (bp) was effective to correct those large defects with many positive outcomes when compared with syntactic materials. Aim: This study aims to establish an experimental model of correction for large diaphragmatic defect with PB and GT patches to compare histologically the tissue interaction between them and diaphragm in young Wistar rats. Materials & Methods: 15 wistar rats were divided in 3 groups: Rats that used BP was named G1;Rats that used GT was named G2;and rats with only scraping in the diphragm, named G3 (control). Animals were submited to a laparotomy and fixed pathces to diaphragms and harvested 3 weeks later. Area between normal diaphragm and patches were isolated and separated for histological analysis, such as lymphocytic infiltration (inflammation), neovascularization and fibrosis. Results: G1 presented inflammation between BP and Diaphragm In 5 Samples. G2 Presented Neovascularization In 5 Samples, But No inflammation. Fibrotic tissue overlapping GT patches occurred in 3 samples in G2. Comparing G1 with G2 there was a significant statistical difference concerning inflammation (P = 0.0079), in G1. Comparing neovascularization there is no significant statistical difference (P = 0.4444), despite a slight higher incidence in G2. Fibrosis in both groups presented no significant statistical difference (P = 0.4444), despite a slight higher incidence in G2. There were no alterations in G3. Discussion: Despite the statistical difference in the inflammatory process was more frequent in G1 (P = 0.0079), neovascularization and fibrosis were more frequent in G2. Conclusion: The proposed experimental model was satisfactory to reproduce suture of patches in the diaphragm. These results suggests that inflammation, neovascularization and fibrosis indeed contribute to a benign healing process that reacts differently in each group but can drive to a more lasting and permanent results when biological patch is considered. Statistical report suggests that this study should be continued with a larger sample of animals and a wider period of time before harvest.

A Biosurfactant-containing TSD Strategy to Modify Bovine Pericardial Bioprosthetic Valves for Anticalcification

Bioprosthetic heart valves(BHVs)are important for transcatheter valve replacement.Current commercial BHVs on the market are basically porcine or bovine pericardium(BP)crosslinked with glutaraldehyde(GA).Simply applying GA to BHVs can enhance mechanical stability,but cannot alleviate in vivo calcification.In this work,we developed a two-step decellularization(TSD)strategy to modify this biomacromolecular network,in which BP was post-treated,as the second step of decellularization,with a mild biosurfactant n-dodecyl-β-D-maltoside in a mixture of isopropanol and phosphate-buffered saline after the first step of traditional decellularization and GA cross-linking.The TSD-treated BP exhibited not only low cytotoxicity and excellent mechanical properties in vitro,but also low immune responses and significant anticalcification in vivo.After 60 days of subcutaneous implantation in the back of Wistar rats,the calcium content was,as quantified with an inductively coupled plasma optical emission spectrometer,only 1.1µg/mg compared to 138.6µg/mg in the control group without the post-treatment.In addition,collagen fibrils were observed with field emitting scanning electron microscopy(SEM),and the morphology and composition of the calcified sites resulting from in vivo biomineralization were studied with SEM with energy dispersive spectroscopy and also X-ray diffraction.This study proposes a facile yet effective anticalcification strategy for the modification of the bovine pericardial bioprosthetic heart valve,a natural biomacromolecular network.

Calcification of Pericardium Treated with Different Phospholipids

Tissue calcification is one of the major factors in the failure of heart valves made of biological tissue materials. The mechanism by which phospholipids function in calcification was studied by lipid removal and lipid addition to investigate the different effects of neutral phosphatidylcholine (PC), negatively charged phosphatidylserine (PS), positively charged phosphatidylethanolamine lysine (PL) and cationic lipid stearylamine (SA) on the calcification. Calcification of bovine pericardium (BP) in a simulated serum was used as a model. The addition of the three phospholipids promoted the calcification of pericardium untreated with glutaraldehyde (GA). However, none of the lipids promoted calcification of the GA treated pericardium. In addition, PL and SA obviously inhibited calcification on GA treated pericardium. The results also showed that alkaline phosphatase (ALP) directly promoted the calcification of pericardium.

Quasi-isothermal modulated DSC as a valuable characterisation method for soft tissue biomaterial crosslinking reactions

Glutaraldehyde(Glut)is an extensively used sterilant and fixative for the crosslinking of natural soft tissue biomaterials like bovine pericardium(BP)to provide stability and is required for its application in vivo.There is plenty of debate around the reaction mechanism of Glut with natural biomaterials.Differential scanning calorimetry(DSC)is a commonly used technique that is typically used to measure the thermal profile of polymers.However,a variation known as quasi-isothermal modulated differential scanning calorimetry(QiMDSC)has been utilised for the analysis of polymorphic transformations in both the pharmaceutical and food industries.This communication will address QiMDSC as a method for analysing soft tissue biomaterials and their crosslinking mechanisms and how it can be applied to other biomaterial applications.