Engineering of a bilayer antibacterial wound dressing from bovine pericardium and electrospun chitosan/PVA/antibiotics for infectious skin wounds management: An in vitro and in vivo study

Tissue deterioration and post-injury infections are the primary cause of skin diseases. Tissue engineering has developed various synthetic and natural polymers to generate bioactive scaffolds that can closely replicate the natural extracellular matrix (ECM). Decellularized tissues have emerged as a potential solution for reconstructing cutaneous lesions due to their ability to preserve the intricate protein structure and provide essential functional domains for cellular differentiation. In this study, we selected bovine pericardium and subjected it to diverse decellularization methods to optimize ECM preservation. Polyvinyl alcohol (PVA)/chitosan (CS) infused with two clinically important antibiotics (colistin and meropenem) was directly electrospun onto the decellularized bovine pericardium (DBPS) to endow the dual-layer scaffold (DBPS-Abs) an antibacterial property. Both DBPS-Abs and DBPS demonstrated a consistent 3D microstructure with interlinked pore networks, minimal degradation, and robust mechanical stability. The DBPS-Abs group exhibited a potent antibacterial effect against standard and clinical strains of Escherichia coli. Moreover, implanting the constructs into full-thickness skin wounds in mice confirmed enhanced wound regeneration in cases treated with DBPS-Abs compared to other groups, observed over a 7- and 21-day post-implantation period. These findings highlight DBPS-Abs as a superior antibacterial wound dressing, requiring further clinical evaluations.

Freezing and bioreactor in the low-concentration detergents: A novel approach in the decellularization of small-diameter arteries

Using decellularized small-diameter vascular bypass substitutes (<6 mm) is an efficient method for bypass grafting. A solution containing 0.5% SDS (weight/volume) is commonly used for extended periods to generate acellular tissues. However, this solution causes damage to the microfibril structure and alters the mechanical forces. Hence, the objective of this study is to reduce the concentration of SDS to preserve the structure and achieve efficient decellularization. The study employs a diluted solution of 0.3% SDS (weight/volume) to treat fresh and frozen swine small-diameter arteries, utilizing physical methods such as freezing and thawing. The effectiveness of cell removal was evaluated using histological analysis and the remaining DNA content of the sample. Furthermore, the acellular circuit also assesses the cytotoxicity and proliferation of HUVECs to gauge their safety. Through the use of 0.3% SDS, a bioreactor system, and freezing-thawing, the pig arteries are successfully decellularized, resulting in residual DNA levels of less than 50 ng/mg dry weight. This process does not cause any major changes to the biomechanical or structural properties of the arteries. The acellular samples exhibit no toxicity on the L929 cell line and promote the growth of HUVECs at their highest rate on the fourth day. This allows for the placement of acellular vascular grafts to evaluate physiological processes within the animal body. This is an important requirement in clinical blood vessel transplantation.

Comparison of Bovine- and Porcine-Derived Decellularized Biomaterials: Promising Platforms for Tissue Engineering Applications

Animal-derived xenogeneic biomaterials utilized in different surgeries are promising for various applications in tissue engineering. However, tissue decellularization is necessary to attain a bioactive extracellular matrix (ECM) that can be safely transplanted. The main objective of the present study is to assess the structural integrity, biocompatibility, and potential use of various acellular biomaterials for tissue engineering applications. Hence, a bovine pericardium (BP), porcine pericardium (PP), and porcine tunica vaginalis (PTV) were decellularized using a Trypsin, Triton X (TX), and sodium dodecyl sulfate (SDS) (Trypsin + TX + SDS) protocol. The results reveal effective elimination of the cellular antigens with preservation of the ECM integrity confirmed via staining and electron microscopy. The elasticity of the decellularized PP (DPP) was markedly (p < 0.0001) increased. The tensile strength of DBP, and DPP was not affected after decellularization. All decellularized tissues were biocompatible with persistent growth of the adipose stem cells over 30 days. The staining confirmed cell adherence either to the peripheries of the materials or within their matrices. Moreover, the in vivo investigation confirmed the biocompatibility and degradability of the decellularized scaffolds. Conclusively, Trypsin + TX + SDS is a successful new protocol for tissue decellularization. Moreover, decellularized pericardia and tunica vaginalis are promising scaffolds for the engineering of different tissues with higher potential for the use of DPP in cardiovascular applications and DBP and DPTV in the reconstruction of higher-stress-bearing abdominal walls.

PROSPECTS FOR APPLICATION OF BOVINE PERICARDIAL SCAFFOLD FOR CARDIAL SURGERY

The aim of the\* study was to estimate the properties of the scaffold obtained by decellularization of bovine pericardium with a 0.1% solution of sodium dodecyl sulfate. The experiment included standard histological, microscopic, molecular genetic, and biomechanical methods. Scaffold was tested in vitro for cytotoxicity and in vivo for biocompatibility. A high degree of removal of cells and their components from bovine pericardium-derived matrix was shown. Biomechanical characteristics of artificial scaffold were the same as those of the native pericardium. With prolonged contact, no cytotoxic effect on human cells was observed. The biointegration of the scaffold in laboratory animals tissues was noted, which confirms the potential possibility of the implant applicationin cardiac surgery.

Effect of Modified Bovine Pericardium on Human Gingival Fibroblasts in vitro

Supportive membranes have recently been applied to treat periodontal disease in order to achieve periodontal tissue regeneration. The crucial role of these membranes is to facilitate the restoration of the structural and functional periodontium. Bovine pericardium (BP) is mainly composed of collagen type I, which was demonstrated to have good mechanical properties and biological regenerative potential. Our research aimed to extend the application of membrane derived from BP to periodontal disease treatment. However, the fabrication method to achieve a xenogenic-free membrane with the mechanical properties required for periodontal treatment is rarely mentioned. Therefore, a procedure for the extraction and modification of BP using sodium dodecyl sulfate (SDS) and glutaraldehyde (GA) was developed. BP was harvested and decellularized using different SDS concentrations (0.05-0.3%). GA was used to further modify the membranes to achieve suitable thickness, mechanical strength, and pore size. A combination protocol of 0.15% SDS treatment for 12 h with continuous agitation combined with 0.1% GA for 6 h for membrane fabricating was applied. The modified BP (mBP) had the targeted characteristics, such as 0.2-0.5 mm thickness, approximately 10 MPa in tensile strength, 30% in strain force, and a pore size <5 µm, which is comparable to commercially available collagen membranes. Findings from this study demonstrated that the established method was effective in preparing BP membrane for periodontal treatment while decreasing the concentration of reagents and processing time. Moreover, our modified membrane was found to have no cytotoxicity but supports the migration, attachment, and proliferation of human gingival fibroblasts in vitro. Taken together, these results confirmed that mBP is suitable for application in periodontal disease treatment and regeneration.

Preparation of high bioactivity multilayered bone-marrow mesenchymal stem cell sheets for myocardial infarction using a 3D-dynamic system

Cell sheet techniques offer a promising future for myocardial infarction (MI) therapy; however, insufficient nutrition supply remains the major limitation in maintaining stem cell bioactivity in vitro. In order to enhance cell sheet mechanical strength and bioactivity, a decellularized porcine pericardium (DPP) scaffold was prepared by the phospholipase A2 method, and aspartic acid was used as a spacer arm to improve the vascular endothelial growth factor crosslink efficiency on the DPP scaffold. Based on this scaffold, multilayered bone marrow mesenchymal stem cell sheets were rapidly constructed, using RAD16-I peptide hydrogel as a temporary 3D scaffold, and cell sheets were cultured in either the 3D-dynamic system (DCcs) or the traditional static condition (SCcs). The multilayered structure, stem cell bioactivity, and ultrastructure of DCcs and SCcs were assessed. The DCcs exhibited lower apoptosis, lower differentiation, and an improved paracrine effect after a 48 h culture in vitro compared to the SCcs. Four groups were set to evaluate the cell sheet effect in rat MI model: sham group, MI control group, DCcs group, and SCcs group. The DCcs group improved cardiac function and decreased the infarcted area compared to the MI control group, while no significant improvements were observed in the SCcs group. Improved cell survival, angiogenesis, and Sca-1⁺ cell and c-kit⁺ cell amounts were observed in the DCcs group. In conclusion, the DCcs maintained higher stem cell bioactivity by using the 3D-dynamic system to provide sufficient nutrition, and transplanting DCcs significantly improved the cardiac function and angiogenesis.

STATEMENT OF SIGNIFICANCE

This study provides an efficient method to prepare vascular endothelial growth factor covalent decellularized pericardium scaffold with aspartic acid, and a multilayered bone marrow mesenchymal stem cell (BMSC) sheet is constructed on it using a 3D-dynamic system. The dynamic nutrition supply showed a significant benefit on BMSC bioactivity in vitro, including decreasing cell apoptosis, reducing stem cell differentiation, and improving growth factor secretion. These favorable bioactivity improved BMSC survival, angiogenesis, and cardiac function of the infarcted myocardium. The study highlights the importance of dynamic nutrition supply on maintaining stem cell bioactivity within cell sheet, and it stresses the necessity and significance of setting a standard for assessing cell sheet products before transplantation in the future application.

A novel surgical technique for a rat subcutaneous implantation of a tissue engineered scaffold

Objectives

Subcutaneous implantations in small animal models are currently required for preclinical studies of acellular tissue to evaluate biocompatibility, including host recellularization and immunogenic reactivity.

Methods

Three rat subcutaneous implantation methods were evaluated in six Sprague Dawley rats. An acellular xenograft made from porcine pericardium was used as the tissue-scaffold. Three implantation methods were performed; 1) Suture method is where a tissue-scaffold was implanted by suturing its border to the external oblique muscle, 2) Control method is where a tissue-scaffold was implanted without any suturing or support, 3) Frame method is where a tissue-scaffold was attached to a circular frame composed of polycaprolactone (PCL) biomaterial and placed subcutaneously. After 1 and 4 weeks, tissue-scaffolds were explanted and evaluated by hematoxylin and eosin (H&E), Masson’s trichrome, Picrosirius Red, transmission electron microscopy (TEM), immunohistochemistry, and mechanical testing.

Results

Macroscopically, tissue-scaffold degradation with the suture method and tissue-scaffold folding with the control method were observed after 4 weeks. In comparison, the frame method demonstrated intact tissue scaffolds after 4 weeks. H&E staining showed progressive cell repopulation over the course of the experiment in all groups with acute and chronic inflammation observed in suture and control methods throughout the duration of the study. Immunohistochemistry quantification of CD3, CD 31, CD 34, CD 163, and αSMA showed a statistically significant differences between the suture, control and frame methods (P < 0.05) at both time points. The average tensile strength was 4.03 ± 0.49, 7.45 ± 0.49 and 5.72 ± 1.34 (MPa) after 1 week and 0.55 ± 0.26, 0.12 ± 0.03 and 0.41 ± 0.32 (MPa) after 4 weeks in the suture, control, and frame methods; respectively. TEM analysis showed an increase in inflammatory cells in both suture and control methods following implantation.

Conclusion

Rat subcutaneous implantation with the frame method was performed with success and ease. The surgical approach used for the frame technique was found to be the best methodology for in vivo evaluation of tissue engineered acellular scaffolds, where the frame method did not compromise mechanical strength, but it reduced inflammation significantly.