Scaffold-Free Tracheal Engineering via a Modular Strategy Based on Cartilage and Epithelium Sheets

The effect of bioactivity of airway epithelial cells using methacrylated gelatin scaffold loaded with exosomes derived from bone marrow mesenchymal stem cells

The current evidence provides support for the involvement of bone marrow mesenchymal stem cells (BMSCs) in the regulation of airway epithelial cells. However, a comprehensive understanding of the underlying biological mechanisms remains elusive. This study aimed to isolate and characterize BMSC-derived exosomes (BMSC-Exos) and epithelial cells (ECs) through primary culture. Subsequently, the impact of BMSC-Exos on ECs was assessed in vitro, and sequencing analysis was conducted to identify potential molecular mechanisms involved in these interactions. Finally, the efficacy of BMSC-Exos was evaluated in animal models in vivo. In this study, primary BMSCs and ECs were efficiently isolated and cultured, and high-purity Exos were obtained. Upon uptake of BMSC-Exos, ECs exhibited enhanced proliferation (p < .05), while migration showed no difference (p > .05). Notably, invasion demonstrated significant difference (p < .05). Sequencing analysis suggested that miR-21-5p may be the key molecule responsible for the effects of BMSC-Exos, potentially mediated through the MAPK or PI3k-Akt signaling pathway. The in vivo experiments showed that the presence of methacrylated gelatin (GelMA) loaded with BMSC-Exos in composite scaffold significantly enhanced epithelial crawling in the patches in comparison to the pure decellularized group. In conclusion, this scheme provides a solid theoretical foundation and novel insights for the research and clinical application of tracheal replacement in the field of tissue engineering.

Bioengineering autologous cartilage grafts for functional posterior lamellar eyelid reconstruction: A preliminary study in rabbits

The reconstruction of posterior lamellar eyelid defects remains a significant challenge in clinical practice due to anatomical complexity, specialized function, and aesthetic concerns. The ideal substitute for the posterior lamellar should replicate the native tarsoconjunctival tissue, providing both mechanical support for the eyelids and a smooth surface for the globe after implantation. In this study, we present an innovative approach utilizing tissue-engineered cartilage (TEC) grafts generated from rabbit auricular chondrocytes and a commercialized type I collagen sponge to reconstruct critical-sized posterior lamellar defects in rabbits. The TEC grafts demonstrated remarkable mechanical strength and maintained a stable cartilaginous phenotype both in vitro and at 6 months post-implantation in immunodeficient mice. When employed as autografts to reconstruct tarsal plate defects in rabbits' upper eyelids, these TEC grafts successfully restored normal eyelid morphology, facilitated smooth eyelid movement, and preserved the histological structure of the conjunctival epithelium. When applied in bilayered tarsoconjunctival defect reconstruction, these TEC grafts not only maintained the normal contour of the upper eyelid but also supported conjunctival epithelial cell migration and growth from the defect margin towards the centre. These findings highlight that auricular chondrocyte-based TEC grafts hold great promise as potential candidates for clinical posterior lamellar reconstruction. STATEMENT OF SIGNIFICANCE: The complex structure and function of the posterior lamellar eyelid continue to be significant challenges for clinical reconstructive surgeries. In this study, we utilized autologous auricular chondrocyte-based TEC grafts for posterior lamellar eyelid reconstruction in a preclinical rabbit model. The TEC grafts exhibited native cartilaginous histomorphology and comparable mechanical strength to those of the native human tarsal plate. In rabbit models with either tarsal plate defects alone or bilayered tarsoconjunctival defects, TEC grafts successfully restored the normal eyelid contour and movement, as well as supported preservation and growth of conjunctival epithelium. This is the first study to demonstrate autologous TEC grafts can be employed for repairing tarsal plate defects, thereby offering an alternative therapeutic approach for treating posterior lamellar defects in clinic settings.

Global Bibliometric and Visualized Analysis of Tracheal Tissue Engineering Research

The development of tracheal tissue engineering (TTE) has seen a rapid growth in recent years. The purpose of this study was to investigate the global status, trends, and hotspots of TTE research based on bibliometrics and visualization analysis. Publications related to TTE were retrieved and included in the Web of Science Core Collection. VOSviewer and CiteSpace were used to generate knowledge maps. Six hundred fifty-five publications were identified, and the quantity of the annual publications worldwide was on the increase. International collaboration is a widespread reality. The United States led the world in the field of trachea tissue engineering, whereas University College London was the institution with the greatest contribution. In addition, Biomaterials had a great influence in this field, attracting the largest number of papers. Moreover, the topics of TTE research largely concentrated on the biomechanical scaffold preparation, the vascularization and epithelialization of scaffold, the tracheal cartilage regeneration, and the tissue-engineered tracheal transplantation. And the research on the application of decellularization and 3D printing for the construction of a tissue-engineered trachea was likely to receive more widespread attention in the future. Impact statement In recent years, tracheal tissue engineering (TTE) has experienced rapid growth. In this study, we investigated the worldwide status and trends of TTE research, and revealed the countries, institutions, journals, and authors that had made significant contributions to the field of TTE. Moreover, the possible research hotspots in the future were predicted. According to our research, researchers can gain a better understanding of the trends in this field, and stay informed of the most current research by tracking key journals, institutions, and authors.

Instant trachea reconstruction using 3D-bioprinted C-shape biomimetic trachea based on tissue-specific matrix hydrogels

Currently, 3D-bioprinting technique has emerged as a promising strategy to offer native-like tracheal substitutes for segmental trachea reconstruction. However, there has been very limited breakthrough in tracheal repair using 3D-bioprinted biomimetic trachea owing to the lack of ideal bioinks, the requirement for precise structural biomimicking, and the complexity of multi-step surgical procedures by mean of intramuscular pre-implantation. Herein, we propose a one-step surgical technique, namely direct end-to-end anastomosis using C-shape 3D-bioprinted biomimetic trachea, for segmental trachea defect repair. First, two types of tissue-specific matrix hydrogels were exploited to provide mechanical and biological microenvironment conducive to the specific growth ways of cartilage and fibrous tissue respectively. In contrast to our previous O-shape tracheal design, the tubular structure of alternating C-shape cartilage rings and connecting vascularized-fibrous-tissue rings was meticulously designed for rapid 3D-bioprinting of tracheal constructs with optimal printing paths and models. Furthermore, in vivo trachea regeneration in nude mice showed satisfactory mechanical adaptability and efficient physiological regeneration. Finally, in situ segmental trachea reconstruction by direct end-to-end anastomosis in rabbits was successfully achieved using 3D-bioprinted C-shape biomimetic trachea. This study demonstrates the potential of advanced 3D-bioprinting for instant and efficient repair of segmental trachea defects.

Surgical Innovations in Tracheal Reconstruction: A Review on Synthetic Material Fabrication

Background and Objectives: The aim of this review is to explore the recent surgical innovations in tracheal reconstruction by evaluating the uses of synthetic material fabrication when dealing with tracheomalacia or stenotic pathologies, then discussing the challenges holding back these innovations. Materials and Methods: A targeted non-systematic review of published literature relating to tracheal reconstruction was performed within the PubMed database to help identify how synthetic materials are utilised to innovate tracheal reconstruction. Results: The advancements in 3D printing to aid synthetic material fabrication have unveiled promising alternatives to conventional approaches. Achieving successful tracheal reconstruction through this technology demands that the 3D models exhibit biocompatibility with neighbouring tracheal elements by encompassing vasculature, chondral foundation, and immunocompatibility. Tracheal reconstruction has employed grafts and scaffolds, showing a promising beginning in vivo. Concurrently, the integration of resorbable models and stem cell therapy serves to underscore their viability and application in the context of tracheal pathologies. Despite this, certain barriers hinder its advancement in surgery. The intricate tracheal structure has posed a challenge for researchers seeking novel approaches to support its growth and regeneration. Conclusions: The potential of synthetic material fabrication has shown promising outcomes in initial studies involving smaller animals. Yet, to fully realise the applicability of these innovative developments, research must progress toward clinical trials. These trials would ascertain the anatomical and physiological effects on the human body, enabling a thorough evaluation of post-operative outcomes and any potential complications linked to the materials or cells implanted in the trachea.

Pre-epithelialized cryopreserved tracheal allograft for neo-trachea flap engineering

Background: Tracheal reconstruction presents a challenge because of the difficulty in maintaining the rigidity of the trachea to ensure an open lumen and in achieving an intact luminal lining that secretes mucus to protect against infection. Methods: On the basis of the finding that tracheal cartilage has immune privilege, researchers recently started subjecting tracheal allografts to "partial decellularization" (in which only the epithelium and its antigenicity are removed), rather than complete decellularization, to maintain the tracheal cartilage as an ideal scaffold for tracheal tissue engineering and reconstruction. In the present study, we combined a bioengineering approach and a cryopreservation technique to fabricate a neo-trachea using pre-epithelialized cryopreserved tracheal allograft (ReCTA). Results: Our findings in rat heterotopic and orthotopic implantation models confirmed that tracheal cartilage has sufficient mechanical properties to bear neck movement and compression; indicated that pre-epithelialization with respiratory epithelial cells can prevent fibrosis obliteration and maintain lumen/airway patency; and showed that a pedicled adipose tissue flap can be easily integrated with a tracheal construct to achieve neovascularization. Conclusion: ReCTA can be pre-epithelialized and pre-vascularized using a 2-stage bioengineering approach and thus provides a promising strategy for tracheal tissue engineering.