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Objectives: This study evaluated the effect of intratracheal administration of basic fibroblast growth factor (bFGF) on tracheal healing following implantation of a novel layered polyglycolic acid (PGA) material to replace a critical-size defect in rat trachea., Methods: A critical-size defect in the rat cervical trachea was covered with PGA. Distilled water (DW) or 3.125, 6.25, 12.5 or 25 µg bFGF was administered into the trachea for 2 weeks (n = 6 for each of 5 groups). Regenerated areas of cilia, ciliary beat frequency and ciliary transport function (CTF) in the centre of the PGA were measured. To examine potential side effects of intratracheal administration of bFGF, the right lower lobe was pathologically evaluated., Results: All rats survived during the study period. Histological examination showed ciliated epithelization on the PGA material after 2 weeks. Bronchoscopy revealed stenosis due to granulation following administration of high concentrations of bFGF (12.5 and 25 µg). Compared with the DW group, groups administered 3.125, 6.25, 12.5 and 25 µg bFGF had significantly larger areas of regenerated cilia (15.2%, 27.0%, 41.3%, 33.1% and 31.0%, respectively; P = 0.00143), improved ciliary beat frequency (7.10, 8.18, 10.10, 9.50 and 9.50 Hz, respectively), and improved CTS (6.40, 9.54, 16.89, 16.41 and 14.29 µm/sec, respectively). Pathological examination of the right lower lobe revealed pulmonary fibrosis and hyperplasia with high concentrations of bFGF (12.5 and 25 µg)., Conclusions: Intratracheal administration of bFGF effectively promoted tracheal regeneration at an optimal dose of 6.25 µg following implantation of an artificial trachea., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Objectives: Polyglycolic acid (PGA) sheets are difficult to adapt to the central airway because of poor durability against high air pressure. Therefore, we developed a novel layered PGA material to cover the central airway and examined its morphologic traits and functional performance as a potential tracheal replacement., Methods: A critical-size defect in rat cervical tracheas was covered with the material. Morphologic changes were bronchoscopically and pathologically evaluated. Functional performance was evaluated by regenerated ciliary area, ciliary beat frequency and ciliary transport function determined by measuring the moving distance of microspheres dropped onto the trachea (µm/s). The evaluation time points were 2 weeks, 1 month, 2 months and 6 months after surgery (n = 5, respectively)., Results: Forty rats underwent implantation, and all survived. Histological examination confirmed ciliated epithelization on the luminal surface after 2 weeks. Neovascularization was observed after 1 month, tracheal glands after 2 months and chondrocyte regeneration after 6 months. Although the material was gradually replaced by self-organization, tracheomalacia was not bronchoscopically observed at any time point. The area of regenerated cilia significantly increased between 2 weeks and 1 month (12.0% vs 30.0%; P = 0.0216). The median ciliary beat frequency significantly improved between 2 weeks and 6 months (7.12 vs 10.04 Hz; P = 0.0122). The median ciliary transport function was significantly improved between 2 weeks and 2 months (5.16 vs 13.49 µm/s; P = 0.0216)., Conclusions: The novel PGA material showed excellent biocompatibility and tracheal regeneration both morphologically and functionally 6 months after tracheal implantation., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Background: Critical obstacles must be addressed before clinical application of artificial tracheas. The major complications of long tracheal replacement include anastomotic dehiscence and stenosis owing to poor vascularity and incomplete reepithelialization. The objective of this report was to clarify whether preincubation of the prosthesis in the omentum could be applicable for reconstruction of a long segment of the intrathoracic trachea in a canine model., Methods: The framework of an artificial trachea was fabricated from a polypropylene mesh tube and coated with 1% neutral atelocollagen inside and outside the lumen. The prosthesis was placed in the omentum of 9 healthy male beagle dogs for 3 weeks. Then, the pedicled prosthesis was used to replace a 50-mm-long section of intrathoracic trachea. Results were evaluated bronchoscopically, macroscopically, and histologically., Results: After 3 weeks of abdominal incubation, the prostheses were incorporated into the host tissue. None of the dogs showed dehiscence of the anastomosis or infection of the prostheses during the postoperative period. Seven of the 9 dogs survived for more than 1 year. One dog died of a bowel obstruction resulting from a diaphragmatic hernia 3 months after replacement, and another died due to reasons unrelated to the prosthesis at 6 months. Bronchoscopic examination revealed no stenosis or dehiscence, and microscopic examination of all dogs showed that the luminal surface was covered by newly regenerated connective tissue and respiratory epithelium., Conclusions: Pedicled omentum-prosthesis complexes may allow successful reconstruction of a long segment of the intrathoracic trachea., (Copyright © 2022 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Objectives: It is unclear whether the movement and function of the regenerated cilia on collagen-conjugated artificial trachea are the same as those of normal cilia. This study assessed the ciliary beat frequency (CBF) and ciliary transport functions (CTFs) of regenerated cilia in a canine model., Methods: A tracheal defect introduced into the anterior portion of the cervical trachea of an adult beagle dog was covered with a collagen-conjugated prosthesis. Two months later, the trachea was harvested along the long axis, both from normal and regenerated regions. The cilia were stained with isothiocyanate-conjugated wheat germ agglutinin, and their movement was monitored with a high-speed camera to analyse CBF and CTF. Four samples each were obtained from the regenerated and normal regions for CBF analysis and 7 samples each were obtained for CTF analysis., Results: The wheat germ agglutinin-stained cells showed well-regulated beats in both the regenerated and normal regions of the trachea. Mean CBF in the regenerated and normal regions did not differ significantly (7.11 ± 0.41 vs 7.14 ± 1.09 Hz; P = 981). By contrast, CTF was significantly lower in the regenerated region than in the normal region (30.0 ± 6.62 vs 7.43 ± 0.58 μm/s; P = 0.005)., Conclusions: Mean CBF in the regenerated and normal regions did not differ significantly at 2 months. The CTF in the regenerated region recovered partially but remained lower than those in the normal region. Methods are needed to improve the CTF of regenerated cilia., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Background: Tracheal reconstruction is complicated by the short length to which a trachea can be resected. We previously developed a biocompatible polypropylene frame artificial trachea, but it lacked the strength and flexibility of the native trachea. In contrast, nitinol may provide these physical characteristics. We developed a novel nitinol frame artificial trachea and examined its biocompatibility and safety in canine models., Methods: We constructed several nitinol frame prototypes and selected the frame that most closely reproduced the strength of the native canine trachea. This frame was used to create a collagen-coated artificial trachea that was implanted into 5 adult beagle dogs. The artificial trachea was first implanted into the pedicled omentum and placed in the abdomen. Three weeks later, the omentum-wrapped artificial trachea was moved into the thoracic cavity. The thoracic trachea was then partially resected and reconstructed using the artificial trachea. Follow-up bronchoscopic evaluation was performed, and the artificial trachea was histologically examined after the dogs were sacrificed., Results: Stenosis at the anastomosis sites was not observed in any dog. Survival for 18 months or longer was confirmed in all dogs but 1, which died after 9 months due to reasons unrelated to the artificial trachea. Histological examination confirmed respiratory epithelial regeneration on the artificial trachea's luminal surface. Severe foreign body reaction was not detected around the nitinol frame., Conclusions: The novel nitinol artificial trachea reproduced the physical characteristics of the native trachea. We have confirmed cell engraftment, good biocompatibility, and survival of 18 months or longer for this artificial trachea in canine models., (Copyright © 2018 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)