Preclinical assessment of resorbable silk splints for the treatment of pediatric tracheomalacia

Establishing Benchmarks for Airway Replacement: Long-Term Outcomes of Tracheal Autografts in a Large Animal Model

OBJECTIVE

Airway replacement is a challenging surgical intervention and remains an unmet clinical need. Due to the risk of airway stenosis, anastomotic separation, poor vascularization, and necrosis, it is necessary to establish the gold-standard outcomes of tracheal replacement. In this study, we use a large animal autograft model to assess long-term outcomes following tracheal replacement.

METHODS

Four New Zealand White rabbits underwent tracheal autograft surgery and were observed for 6 months. Clinical and radiographic surveillance were recorded, and grafts were analyzed histologically and radiographically at endpoint.

RESULTS

All animals survived to the endpoint with minimal respiratory symptoms and normal growth rates. No complications were observed. Computed tomography scans of the post-surgical airway demonstrated graft patency at all time points. Histological sections showed no sign of stenosis or necrosis with preservation of the native structure of the trachea.

CONCLUSION

We established benchmarks for airway replacement. Our findings suggest that a rabbit model of tracheal autograft with direct reimplantation is feasible and does not result in graft stenosis or airway collapse.

Renal tissue engineering for regenerative medicine using polymers and hydrogels

Chronic Kidney Disease (CKD) is a growing worldwide problem, leading to end-stage renal disease (ESRD). Current treatments for ESRD include haemodialysis and kidney transplantation, but both are deemed inadequate since haemodialysis does not address all other kidney functions, and there is a shortage of suitable donor organs for transplantation. Research in kidney tissue engineering has been initiated to take a regenerative medicine approach as a potential treatment alternative, either to develop effective cell therapy for reconstruction or engineer a functioning bioartificial kidney. Currently, renal tissue engineering encompasses various materials, mainly polymers and hydrogels, which have been chosen to recreate the sophisticated kidney architecture. It is essential to address the chemical and mechanical aspects of the materials to ensure they can support cell development to restore functionality and feasibility. This paper reviews the types of polymers and hydrogels that have been used in kidney tissue engineering applications, both natural and synthetic, focusing on the processing and formulation used in creating bioactive substrates and how these biomaterials affect the cell biology of the kidney cells used.

Novel Therapy for Acquired Tracheomalacia with a Tissue-Engineered Extraluminal Tracheal Splint and Autologous Mesenchymal-Derived Chondrocytes

Introduction Acquired tracheomalacia (ATM) is characterized by a loss of structural strength of the tracheal framework, resulting in airway collapse during breathing. Near half of the patients undergoing prolonged invasive mechanical ventilation will suffer tracheal lesions. Treatment for ATM includes external splinting with rib grafts, prosthetic materials, and tracheal resection. Failure in the use of prosthetic materials has made reconsidering natural origin scaffolds and tissue engineering as a suitable alternative.

Objective To restore adequate airway patency in an ovine model with surgically-induced ATM employing a tissue-engineered extraluminal tracheal splint (TE-ETS).

Methods In the present prospective pilot study, tracheal rings were partially resected to induce airway collapse in 16 Suffolk sheep (Ovis aries). The TE-ETS was developed with autologous mesenchymal-derived chondrocytes and allogenic decellularized tracheal segments and was implanted above debilitated tracheal rings. The animals were followed-up at 8, 12, and 16 weeks and at 1-year postinsertion. Flexible tracheoscopies were performed at each stage. After sacrifice, a histopathological study of the trachea and the splint were performed.

Results The TE-ETS prevented airway collapse for 16 weeks and up to 1-year postinsertion. Tracheoscopies revealed a noncollapsing airway during inspiration. Histopathological analyses showed the organization of mesenchymal-derived chondrocytes in lacunae, the proliferation of blood vessels, and recovery of epithelial tissue subjacent to the splint. Splints without autologous cells did not prevent airway collapse.

Conclusion It is possible to treat acquired tracheomalacia with TE-ETS without further surgical removal since it undergoes physiological degradation. The present study supports the development of tissue-engineered tracheal substitutes for airway disease.

Resorbable airway splint, stents, and 3D reconstruction and printing of the airway in tracheobronchomalacia

Tracheobronchomalacia (TBM) is the most common tracheobronchial obstruction. Most cases are mild to moderate; therefore, they do not need surgical treatment. Severe tracheomalacia, however, represents a diagnostic and therapeutic challenge since they are very heterogeneous. In the armamentarium of resources for the treatment of dynamic airway collapse, splints and stents are two underused strategies and yet, they may represent the best alternative in selected cases. Lately, computed tomography 3D reconstruction of the airway has been used for the design of virtual models that can be 3D-printed for the creation of novel devices to address training, simulation, and biotechnological implants for refractory and severe airway malformations. This manuscript examines the role of resorbable stents, splints, and the 3D reconstruction and printing of the pediatric airway in tracheobronchomalacia.