Isolation of multipotent progenitor cells from pleura and pericardium for tracheal tissue engineering purposes

Functional outcome of cell seeded tracheal scaffold after mechanical stress in vitro

Tracheal tissue engineering is still facing major challenges: realization of efficient vascularization and mechanical properties comparable to native trachea need to be achieved. In this study, we present a strategy for the manufacturing of a construct for tracheal tissue engineering by conditioning through cell seeding followed by mechanical stimulation in vitro. Scaffolds derived from porcine trachea decellularized with supercritical carbon dioxide were seeded with stem cells of different tissue sources and cultured in a bioreactor for 21 days under mechanical stimulation. Enhanced chondrogenic development was demonstrated, with improved sulphated glycosaminoglycan secretion and cellular alignment which resulted in mechanical properties resembling native trachea. This method may provide a useful addition to tracheal tissue engineering strategies aimed at optimizing cartilage formation.

Biomechanical evaluation of a sheep tracheal scaffold

Tissue engineering is a set of techniques for producing or reconstructing tissue that primarily aims to restore or improve the function of tissues in the human body. The aim of the present study was to evaluate the mechanical and histological characteristics of decellularized tracheal scaffolds prepared in comparison with fresh trachea for use in tracheal repair. In order to prepare the scaffold, sheep's trachea was prepared and after cleaning the waste tissues, they were decellularized. Then decellularized scaffolds were evaluated histologically and laboratory and numerical study of the nonlinear mechanical behavior of tracheal tissue and scaffold and their comparison. Examining the results of histological evaluations showed that the decellularization of the scaffolds was completely done. These results were confirmed by hematoxylin-eosin staining. Also, the exact hyperelastic properties of tracheal tissue and scaffold were used in biomechanical models, and according to the presented results, the five-term Mooney-Rivlin strain energy density function became a suitable behavioral model for modeling the hyperelastic behavior of trachea and scaffold. In total, the results of this research showed that the scaffolds obtained from decellularization by preserving the main compositions of the desired tissue can be a suitable platform for investigating cell behaviors.

Scaffold-based tissue engineering: Supercritical carbon dioxide as an alternative method for decellularization and sterilization of dense materials

Development of ready-to-use biomaterials and scaffolds is vital for further advancement of scaffold-based tissue engineering in clinical practice. Scaffolds need to mimic 3D ultrastructure, have adequate mechanical strength, are biocompatible, non-immunogenic and need to promote tissue regeneration in vivo. Although decellularization of native tissues seems promising to deliver scaffolds that meet these criteria, adequate decellularization of hard, poorly penetrable and poorly diffusible tissues remains challenging whilst being a very time-consuming process. In this study, a method to decellularize hard, dense tissues using supercritical carbon-dioxide preceded by a freeze/thaw cycle and followed by several washing steps is presented, demonstrating decellularisation efficiency and substantially reduced production/handling time. Additionally, supercritical carbon-dioxide treatment was used as sterilization method, further reducing the time required to produce the final scaffold. Histological evaluation showed that, after fine-tuning of the process, a partially acellular scaffold was obtained, with preservation of glycosaminoglycans and collagen fibers, albeit that the amount of residual dsDNA was still higher then chemically decellularized tissue. Biomechanical properties of the scaffold were similar to the native, non-decellularized tissue. After sterilization with supercritical carbon-dioxide the simulated functional outcome was more similar to native trachea, when compared to sterilization using gamma irradiation. Thus, decellularization and sterilization using supercritical carbon-dioxide with washing steps is an effective method for dense cartilaginous materials, and tuneable to meet different demands in other applications, but further optimization may be required. STATEMENT OF SIGNIFICANCE: Further advancement of the use of tissue engineered tracheal constructs is restricted by the lack of the ideal scaffold. Decellularized trachea is considered a promising scaffold, but the hard, poorly diffusible tissue remains challenging while forming a very time consumable process. Decellularization using supercritical carbon dioxide (scCO₂) seems promising, resulting in efficient removal of cellular material while reducing production and handling time. Addition of scCO₂ as a sterilization method resulted in further time reduction while improving functional outcome in comparison with traditional sterilization methods. This study presents an promising alternative method for decellularization and sterilization of dense materials, which can be tuned to meet different demands in other applications.

Poly (L-Lactic Acid) Cell-Laden Scaffolds Applied on Swine Model of Tracheal Fistula

INTRODUCTION

Tracheal fistula (TF) treatments may involve temporary orthosis and further ablative procedures, which can lead to infection. Thus, TF requires other therapy alternatives development. The hypothesis of this work was to demonstrate the feasibility of a tissue-engineered alternative for small TF in a preclinical model. Also, its association with suture filaments enriched with adipose tissue-derived mesenchymal stromal stem cells (AT-MSCs) was assessed to determine whether it could optimize the regenerative process.

METHODS

Poly (L-Lactic acid) (PLLA) membranes were manufactured by electrospinning and had morphology analyzed by scanning electron microscopy. AT-MSCs were cultured in these scaffolds and in vitro assays were performed (cytotoxicity, cellular adhesion, and viability). Subsequently, these cellular constructs were implanted in an animal small TF model. The association with suture filaments containing attached AT-MSCs was present in one animal group. After 30 d, animals were sacrificed and regenerative potential was evaluated, mainly related to the extracellular matrix remodeling, by performing histopathological (Hematoxylin-Eosin and trichrome Masson) and immunohistochemistry (Collagen I/II/III, matrix metalloproteinases-2, matrix metalloproteinases-9, vascular endothelial growth factor, and interleukin-10) analyses.

RESULTS

PLLA membranes presented porous fibers, randomly oriented. In vitro assays results showed that AT-MSCs attached were viable and maintained an active metabolism. Swine implanted with AT-MSCs attached to membranes and suture filaments showed aligned collagen fibers and a better regenerative progress in 30 d.

CONCLUSIONS

PLLA membranes with AT-MSCs attached were useful to the extracellular matrix restoration and have a high potential for small TF treatment. Also, their association with suture filaments enriched with AT-MSCs was advantageous.

Inflammation of the Pleural Cavity: A Review on Pathogenesis, Diagnosis and Implications in Tumor Pathophysiology

Pleural effusions are a common respiratory condition with many etiologies. Nonmalignant etiologies explain most pleural effusions and despite being nonmalignant, they can be associated with poor survival; thus, it is important to understand their pathophysiology. Furthermore, diagnosing a benign pleural pathology always harbors the uncertainty of a false-negative diagnosis for physicians and pathologists, especially for the group of non-specific pleuritis. This review aims to present the role of the inflammation in the development of benign pleural effusions, with a special interest in their pathophysiology and their association with malignancy.