Composite cervical skin and cartilage flap provides a novel large airway substitute after long-segment tracheal resection

The Growing Medical Need for Tracheal Replacement: Reconstructive Strategies Should Overcome Their Limits

Breathing, being predominantly an automatic action, is often taken for granted. However, respiratory diseases affect millions of people globally, emerging as one of the major causes of disability and death overall. Among the respiratory dysfunctions, tracheal alterations have always represented a primary challenge for clinicians, biologists, and engineers. Indeed, in the case of wide structural alterations involving more than 50% of the tracheal length in adults or 30% in children, the available medical treatments are ineffective or inapplicable. So far, a plethora of reconstructive approaches have been proposed and clinically applied to face this growing, unmet medical need. Unfortunately, none of them has become a well-established and routinely applied clinical procedure to date. This review summarizes the main clinical reconstructive attempts and classifies them as non-tissue engineering and tissue engineering strategies. The analysis of the achievements and the main difficulties that still hinder this field, together with the evaluation of the forefront preclinical experiences in tracheal repair/replacement, is functional to promote a safer and more effective clinical translation in the near future.

Tracheal reconstruction with pedicled tandem grafts engineered by a radial stretch bioreactor

The engineering of tracheal substitutes is pivotal in improving tracheal reconstruction. In this study, we aimed to investigate the effects of biomechanical stimulation on tissue engineering tracheal cartilage by mimicking the trachea motion through a novel radial stretching bioreactor, which enables to dynamically change the diameter of the hollow cylindrical implants. Applying our bioreactor, we demonstrated that chondrocytes seeded on the surface of Poly (ε-caprolactone) scaffold respond to mechanical stimulation by improvement of infiltration into implants and upregulation of cartilage-specific genes. Further, the mechanical stimulation enhanced the accumulation of cartilage neo-tissues and cartilage-specific extracellular macromolecules in the muscle flap-remodeled implants and reconstructed trachea. Nevertheless, the invasion of fibrous tissues in the reconstructed trachea was suppressed upon mechanical loading.

Large animal models for long-segment tracheal reconstruction: a systematic review

BACKGROUND

The reconstruction of extensive tracheal defects is an unresolved problem. Despite decades of research, a reliable and practical substitute remains to be found. While there have been clinical reports of successful long-segment tracheal reconstruction, reproducibility and widespread applicability of these techniques have yet to be achieved. Large animals such as the dog, pig, sheep, and goat have comparable tracheal morphology and physiology to humans making them useful preclinical models to screen potential therapeutic strategies.

MATERIALS AND METHODS

The literature was reviewed to identify large animal models commonly used for tracheal reconstruction. A systematic search of PubMed and EMBASE was performed for large animal studies reporting on the reconstruction of long-segment tracheal and carinal defects. Fifty-seven studies were identified for analysis.

RESULTS

There is no standard large animal model available for tracheal research. In recent years, livestock species have gained favor over dogs as animal models in this field. The minimum requirements for successful tracheal replacement are rigidity, vascularity, and epithelial lining. Early attempts with synthetic prostheses were met with disappointing results. An autologous tracheal substitute is ideal but hindered by limited donor site availability and the lack of a dominant vascular pedicle for microsurgical reconstruction. Although tracheal allotransplantation enables like-for-like replacement, there are unresolved issues relating to graft vascularity, immunosuppression, and graft preservation. Tissue engineering holds great promise; however, the optimal combination of scaffold, cells, and culture conditions is still indeterminate.

CONCLUSIONS

Despite impressive advances in tracheal reconstruction, a durable substitute for extended tracheal defects continues to be elusive.

Surgical management of children presenting with surgical-needed tracheal stenosis

OBJECTIVES

The purpose of this work was to assess epidemiological aspects, surgical approach, morbidity and mortality rates of patients presenting with tracheal stenosis requiring surgery, and the evolution of surgical techniques over the last years.

METHODS

We performed a retrospective observational study from 1990 to 2017 in a pediatric tertiary-care center with needing surgery for tracheal stenosis. We analyzed clinical patients' characteristics, type of stenosis, type of surgery and follow-up.

RESULTS

Twenty-eight children presented with tracheal stenosis, half of them with congenital stenosis (complete tracheal rings) and the other half with acquired stenosis (neoplasic or post intubation injury). 39.3% of these stenoses were associated with a vascular ring (61.5% in case of congenital stenosis). Depending on the extent of the stenosis and its origin, the surgery could be performed endoscopically or by an external approach. Enlargement tracheoplasty with an autograft (14.3%) was replaced by slide tracheoplasty with Cardio Pulmonary By-Pass (CPBP, 28.6%) with improved results for the treatment of long segment tracheal stenosis, involving more than 30% of the tracheal length (all were congenital in our study). Slide tracheoplasty has been performed since the late 90's in our institution. 25% of children have had a resection and anastomosis of the trachea because they had a stenosis involving less than 30% of tracheal length. Endoscopic surgery was performed for membranous stenoses, which were often seen after intubation or tracheotomy (32.1% of patients).

CONCLUSION

Effective treatment of surgical tracheal stenosis was performed in 28 children between 1990 and 2015. Surgical techniques have evolved over time, leading to a better management of this rare and serious disease.

Tracheal replacement

Tracheal reconstruction is one of the greatest challenges in thoracic surgery when direct end-to-end anastomosis is impossible or after this procedure has failed. The main indications for tracheal reconstruction include malignant tumours (squamous cell carcinoma, adenoid cystic carcinoma), tracheoesophageal fistula, trauma, unsuccessful surgical results for benign diseases and congenital stenosis. Tracheal substitutes can be classified into five types: 1) synthetic prosthesis; 2) allografts; 3) tracheal transplantation; 4) tissue engineering; and 5) autologous tissue composite. The ideal tracheal substitute is still unclear, but some techniques have shown promising clinical results. This article reviews the advantages and limitations of each technique used over the past few decades in clinical practice. The main limitation seems to be the capacity for tracheal tissue regeneration. The physiopathology behind this has yet to be fully understood. Research on stem cells sparked much interest and was thought to be a revolutionary technique; however, the poor long-term results of this approach highlight that there is a long way to go in this research field. Currently, an autologous tissue composite, with or without a tracheal allograft, is the only long-term working solution for every aetiology, despite its technical complexity and setbacks.

Advances in tracheal reconstruction

SUMMARY

A recent revival of global interest for reconstruction of long-segment tracheal defects, which represents one of the most interesting and complex problems in head and neck and thoracic reconstructive surgery, has been witnessed. The trachea functions as a conduit for air, and its subunits including the epithelial layer, hyaline cartilage, and segmental blood supply make it particularly challenging to reconstruct. A myriad of attempts at replacing the trachea have been described. These along with the anatomy, indications, and approaches including microsurgical tracheal reconstruction will be reviewed. Novel techniques such as tissue-engineering approaches will also be discussed. Multiple attempts at replacing the trachea with synthetic scaffolds have been met with failure. The main lesson learned from such failures is that the trachea must not be treated as a "simple tube." Understanding the anatomy, developmental biology, physiology, and diseases affecting the trachea are required for solving this problem.

Advances in tracheal reconstruction

Summary:

A recent revival of global interest for reconstruction of long-segment tracheal defects, which represents one of the most interesting and complex problems in head and neck and thoracic reconstructive surgery, has been witnessed. The trachea functions as a conduit for air, and its subunits including the epithelial layer, hyaline cartilage, and segmental blood supply make it particularly challenging to reconstruct. A myriad of attempts at replacing the trachea have been described. These along with the anatomy, indications, and approaches including microsurgical tracheal reconstruction will be reviewed. Novel techniques such as tissue-engineering approaches will also be discussed. Multiple attempts at replacing the trachea with synthetic scaffolds have been met with failure. The main lesson learned from such failures is that the trachea must not be treated as a “simple tube.” Understanding the anatomy, developmental biology, physiology, and diseases affecting the trachea are required for solving this problem.

Surgical management of benign tracheal stenosis

This chapter provides a step-by-step explanation of the indications, basic technique and pitfalls of tracheal surgery for cases of benign tracheal stenosis. Approach, trachea dissection and end-to-end anastomosis in tracheal surgery is described in detail. An algorithm for laryngotracheal technique selection according to different criteria (stenosis location, vocal cords status and tracheal mucosa and/or cartilaginous larynx involvement) is also depicted. Finally, a review of the most important reported series in tracheal surgery is presented.

Successful tracheal replacement in humans using autologous tissues: an 8-year experience

BACKGROUND

Fifty years of surgical research using synthetic materials and heterologous tissues failed to find a good, durable replacement for the trachea. We investigated autologous tracheal substitution (ATS) without synthetic material or immunosuppression.

METHODS

For ATS, we used a single-stage operation to construct a tube from a forearm free fasciocutaneous flap vascularized by radial vessels that was reanastomosed to internal mammary vessels and reinforced by rib cartilages interposed transversally in the subcutaneous tissue. Tracheal resections 7 to 12 cm long (mean, 11 cm) were done to treat 8 primary tracheal neoplasms, including 5 adenoid cystic carcinomas (ACC) and 3 squamous cell carcinomas (SCC); 3 secondary tracheal neoplasms, including 1 thyroid carcinomas and 2 lymphomas; and 1 postintubation tracheal destruction after a long history of stenting. Transitory tracheotomy was associated to the absence of mucociliary clearance.

RESULTS

ATS has been performed in 12 patients since 2004, with additional resections in 4 patients, comprising 1 carinal resection alone, 1 associated with lobectomy, and 2 pharyngolaryngectomies. All patients were extubated on postoperative day 1. Eight patients are alive at a mean of 36 months (range, 2 to 94 months) postoperatively, with no respiratory distress. The 2 patients with ATS and carinal resections died of pulmonary infection. No airway collapse has been detected by endoscopy, dynamic computed tomography scan, or spirometry. Two patients still have a tracheotomy because the procedure was performed too low at the level of the proximal anastomosis. One patient with a chronic severe respiratory insufficiency recently required a distal, short stent.

CONCLUSIONS

ATS is a good, durable, tracheal substitution that resists respiratory pressure variations because of transverse rigidity, without any immunosuppression.

Autologous tracheal replacement: from research to clinical practice

BACKGROUND

Despite numerous attempts, synthetic materials and heterologous tissues failed to replace durably the trachea. Autologous tracheal substitution (ATS) without synthetic material or immunosuppression was investigated to replace extended tracheal defect. We present our experience regards to this innovative challenge.

METHOD

After a previous research study, we developed a novel reconstruction technique for extended tracheal defects on animals. Through a single stage operation, a tube from a forearm free fascio-cutaneous flap vascularized by radial vessels is re-anastomosed to cervical vessels. This flap is reinforced by rib cartilages interposed transversally in the subcutaneous tissue. It provides also a reliable ATS. Twelve patients benefits from an extended tracheal resections, 7-12 centimeter (mean 11 cm) long. Indications were eight Primary tracheal Neoplasms (including 5 adenoid cystic carcinoma [ACC] and 3 squamous cell carcinoma [SCC]), three secondary tracheal neoplasms (including 1 thyroid carcinoma and 2 lymphoma) and one post-intubation tracheal destruction after long history of stenting. Daily bronchoscopy and transitory tracheotomy was associated due to absence of mucociliary clearance.

RESULTS

The research work leads to present the first described animal model for tracheal resection and replacement with an autologous conduit. It was constructed from costal cartilages and a pediculed cervical skin flap. From 2004 to 2012, 12 patients have had ATS with associated resections in four cases. All patients were extubated on the first postoperative days; eight patients are alive at 2 to 94 months (mean=36) postoperatively, with no respiratory distress. The two patients with ATS after resection extended to the carina died due to pulmonary infection. No airway collapse has been detectable, either by endoscopy, dynamic CT scan or spirometry. Two patients still have a tracheotomy because performed too low at the level of the proximal anastomosis. One patient with a chronic severe respiratory insufficiency required recently a distal and short stent.

CONCLUSION

ATS is actually a good, durable tracheal substitute that can resist respiratory pressure variations because of their transverse rigidity without any immunosuppression. The limits of this technique are probably, chronic respiratory insufficiency and cartilage calcifications. Research to develop a method for lining the neo-trachea with ciliated respiratory epithelium is needed.