Reconstruction of the Cervical Trachea Using a Prefabricated Corticoperiosteal Flap From the Femur

Dynamic flow for efficient partial decellularization of tracheal grafts: A preliminary rabbit study

Objective

Bioengineered tracheal grafts are a potential solution for the repair of long-segment tracheal defects. A recent advancement is partially decellularized tracheal grafts (PDTGs) which enable regeneration of host epithelium and retain viable donor chondrocytes for hypothesized benefits to mechanical properties. We propose a novel and tunable 3D-printed bioreactor for creating large animal PDTG that brings this technology closer to the bedside.

Methods

Conventional agitated immersion with surfactant and enzymatic activity was used to partially decellularize New Zealand white rabbit (Oryctolagus cuniculus) tracheal segments (n = 3). In parallel, tracheal segments (n = 3) were decellularized in the bioreactor with continuous extraluminal flow of medium and alternating intraluminal flow of surfactant and medium. Unprocessed tracheal segments (n = 3) were also collected as a control. The grafts were assessed using the H&E stain, tissue DNA content, live/dead assay, Masson's trichrome stain, and mechanical testing.

Results

Conventional processing required 10 h to achieve decellularization of the epithelium and submucosa with poor chondrocyte viability and mechanical strength. Using the bioreactor reduced processing time by 6 h and resulted in chondrocyte viability and mechanical strength similar to that of native trachea.

Conclusion

Large animal PDTG created using our novel 3D printed bioreactor is a promising approach to efficiently produce tracheal grafts. The bioreactor offers flexibility and adjustability favorable to creating PDTG for clinical research and use. Future research includes optimizing flow conditions and transplantation to assess post-implant regeneration and mechanical properties.

Level of Evidence

NA.

Skin-derived epithelial lining facilitates orthotopic tracheal transplantation by protecting the tracheal cartilage and inhibiting granulation hyperplasia

Long-segment tracheal defects caused by tumours, inflammation or trauma can cause serious damage to the quality of life of patients. Although many novel neotracheas have been constructed, the therapeutic effect of orthotopic transplantation was compromised mainly because of the lack of an epithelial lining in those neotracheas. In this study, we aimed to investigate the therapeutic function of skin-derived epithelial lining for orthotopic tracheal transplantation. Strips of auricular cartilage with fixed interval were interrupted sutured on a silicone tube to mimic the cartilage rings of the native trachea. Neotrachea in the with epithelium group retained the unilateral skin as the epithelial lining in the lumen, whereas the neotrachea in the without epithelium group consisted solely of cartilage strips. After revascularized in the sternohyoid muscle, 2-cm-long tracheal defects were made and were reconstructed using these neotracheas. Our results showed that the skin-derived epithelial lining simultaneously protected the engineered tracheal cartilage and inhibited granulation hyperplasia in the tracheal lumen; further, compared with the without epithelium group, the group with epithelium showed a marked improvement in the tracheal lumen patency and the survival rate of rabbits. Our study provides a critical cue for improvements in the repair of tracheal defects via skin-derived epithelial lining and may significantly advance the clinical translation of tissue-engineered trachea.

Microvascular reconstruction of the mandible with medial femoral condylar flap for treatment of mandibular non-union

Mandibular non-union occurs in 2-9% after open reduction and internal fixation of a mandibular fracture (trauma surgery, orthognathic cases, access osteotomy for oncological purposes). The medial femoral condyle (MFC) has emerged more recently as one of the most versatile donor sites in the treatment of challenging bone reconstruction. This is the first description of MFC for treatment of mandibular non-union. A retrospective chart review was conducted for all patients who underwent reconstruction with a microvascular MFC flap for bone defects of the head and neck area between January 2015 and December 2018 at Careggi Hospital of Florence. Inclusion criteria were patients where the FMC was used for mandibular defects arising due to non-union. Seven patients presented mandibular defects reconstructed by MFC flap and were included in this investigation (two cases of segmental mandible defect due to post-traumatic non-union; two patients of pathological mandibular fracture after prolonged bisphosphonate therapy for osteoporosis; three patients with mandibular continuity loss after failed orthognathic surgeries). At one-year follow-up, all patients had satisfactory occlusion. One-year postoperative CTs revealed full osteointegration of the flaps. In conclusion, the MFC free flap is an attractive option for mandibular reconstruction. Small defects (3-5 cm) in poorly vascularized beds are the ideal target.

The prefabricated supraclavicular artery flap in high-risk tracheal stenosis patients

OBJECTIVES/HYPOTHESIS

Primary tracheal resection in appropriately selected patients with tracheal stenosis achieves >90% success rate. Risk factors for complications have been identified, making some patients high risk for this procedure. Herein is a review and discussion of a novel treatment method for tracheal stenosis utilizing a prefabricated composite auricular cartilage graft embedded in a supraclavicular artery island flap (pSCAIF) for tracheal reconstruction in high-risk patients.

STUDY DESIGN

Retrospective case series.

METHODS

After institutional review board approval, cases were analyzed after data collection. Between 2014 and 2016, eight patients underwent airway reconstruction using an auricular cartilage graft prefabricated within a supraclavicular artery island flap reconstruction; all of these were included in the study. Each case was reviewed, and relevant details of patient and disease characteristics, operative course, postoperative course, decannulation, and status at last follow-up were isolated and reported.

RESULTS

Seven of eight patients were female. The most common cause of stenosis was iatrogenically induced multilevel stenosis (7/8 patients). All patients had undergone prior airway procedures, were high risk based on comorbid conditions, and underwent grafting and reconstruction with a composite supraclavicular island flap. All patients continue to follow up in a multidisciplinary clinic, and at last follow-up, eight of eight patients were successfully decannulated.

CONCLUSIONS

The pSCAIF is a novel method for tracheal reconstruction. The analysis of the prefabricated locoregional approach cohort supports its utility for tracheal reconstruction in patients with complicated multilevel stenosis and adverse comorbidities and characteristics.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:641-648, 2020.

Regeneration of trachea graft with cartilage support, vascularization, and epithelization

The repair and functional reconstruction of long-segment tracheal defects is always a great challenge in the clinic. Finding an ideal substitute for tracheal transplantation is the only way to solve this problem. The current study proposed a series of novel strategies for constructing a bionic living trachea substitute. For the issue of tubular cartilage support, cartilage sheet technique based on high-density culture of chondrocytes was adopted to avoid the inflammatory reaction triggered by the materials and thus formed mature cartilage-like tissue in autologous goat model. For the issue of epithelialization, the autologous transplantation of oral mucosal epithelium was used to realize mucosa coverage of the constructed trachea lumen. Finally, the flat trapezius fascia flap with double blood supply was separated by microsurgical techniques to achieve stable pre-vascularization of both the regenerated cartilage and the grafted epithelium simultaneously. By integrating the above strategies, the vascularized and epithelialized tracheal substitute with tubular cartilage support was successfully constructed in a goat model. The reconstructed trachea possessed a multiple layer structure of muscle-cartilage-fascia-mucosa comparable to the native trachea, and thus might realize stable survival and long-term airway function maintenance, providing a promising tracheal substitute for the repair and permanent functional reconstruction of long-segment tracheal defects. STATEMENT OF SIGNIFICANCE: The repair of long-segment tracheal defects is always a great challenge in the clinic. Finding an ideal substitute for tracheal transplantation is the only way to solve this problem. In the current study, by technical integration of cartilage regeneration, microsurgery, and oral mucosa transplantation, a complex tracheal substitute with satisfactory vascularization, epithelialization, and tubular cartilage support was successfully constructed in a goat autologous model. The reconstructed trachea substitute possessed a multiple layer structure of muscle-cartilage-fascia-mucosa exactly similar to native trachea, and thus might realize stable survival and long-term airway function maintenance. The current study provides feasible strategies and ideal tracheal substitutes for permanent functional reconstruction of long-segmental trachea defects.

One-Step Laryngotracheal Reconstruction With Prefabricated Corticoperiosteal Flap

Large airway reconstruction is difficult and requires a flap that will mirror the tissue variety. The main challenge is to keep the reconstruction stable and prevent collapse. In this report, we present a laryngotracheal reconstruction with a buccal mucosa-prefabricated medial femoral condyle free flap, after chondroma excision in a 1-step procedure. Functional results are promising and were confirmed by endoscopy and computed tomography examination 12 months postoperatively. This reconstruction-with-prefabrication technique, among others, may be used in the reconstruction of different regions like craniofacial bone defects, apart from larynx and trachea.

Immediate tracheal reconstruction with forearm flap and bone graft

BACKGROUND

"Window" resection of the trachea is sometimes performed to remove tumors invading the trachea. Here, we present a novel reconstructive procedure to this end.

METHODS

Eleven patients (mean age, 64 years; range, 46-80 years) were included. Primary diagnoses included thyroid cancer and adenoid cystic carcinoma of the trachea. All defects were partial and located in the neck (mean width and length, 3/5 circle and 7.5 rings; range, 1/2-2/3 circle and 5-9 rings). Immediate 2-stage reconstruction was performed using a forearm flap and free bone graft. The bone graft was utilized as a supportive skeleton. A tracheostoma was left open for several months following the initial surgery, and then closed.

RESULTS

The mean flap size was 6.1 × 9.7 cm (range, 6-7 × 7-16 cm). Mean number of grafted bone strips and length were 1.6 (range, 1-3) and 6.1 cm (range, 4.5-7 cm). All flaps survived. Five patients developed complications in the neck, including surgical site infections (SSIs), recurrent nerve palsy, and lymphorrhea. Four patients developed donor site complications, including clavicular fracture and SSIs. Mean postoperative follow-up lasted 85 months (range, 11-149 months). Normal speech was restored in 9 patients. Stoma closure was abandoned in 2 patients, because 1 patient showed vocal cord fixation with advanced age and the other showed bone graft loss following SSI.

CONCLUSIONS

Creating a tracheostoma during the first operation prevents postoperative airway compromise. Our bone graft placement easily achieves tracheal rigidity. This procedure is simple and safe for tracheal window defect repair.

Regeneration of Tracheal Tissue in Partial Defects Using Porcine Small Intestinal Submucosa

Background

Surgical correction of tracheal defects is a complex procedure when the gold standard treatment with primary end-to-end anastomosis is not possible. An alternative treatment may be the use of porcine small intestinal submucosa (SIS). It has been used as graft material for bioengineering applications and to promote tissue regeneration. The aim of this study was to evaluate whether SIS grafts improved tracheal tissue regeneration in a rabbit model of experimental tracheostomy.

Methods

Sixteen rabbits were randomized into two groups. Animals in the control group underwent only surgical tracheostomy, while animals in the SIS group underwent surgical tracheostomy with an SIS graft covering the defect. We examined tissues at the site of tracheostomy 60 days after surgery using histological analysis with hematoxylin and eosin (H&E) staining and analyzed the perimeter and area of the defect with Image-Pro® PLUS 4.5 (Media Cybernetics).

Results

The average perimeter and area of the defects were smaller by 15.3% (p = 0.034) and 21.8% (p = 0.151), respectively, in the SIS group than in the control group. Histological analysis revealed immature cartilage, pseudostratified ciliated epithelium, and connective tissue in 54.5% (p = 0.018) of the SIS group, while no cartilaginous regeneration was observed in the control group.

Conclusions

Although tracheal SIS engraftment could not prevent stenosis in a rabbit model of tracheal injury, it produced some remarkable changes, efficiently facilitating neovascularization, reepithelialization, and neoformation of immature cartilage.

Tracheal repair with acellular human amniotic membrane in a rabbit model

Surgical correction of tracheal stenosis is still a complex and challenging procedure. Acellular human amniotic membranes (AHAM) represent a promising biomaterial source for tissue regeneration. The aim of this study was to evaluate whether AHAM grafts improve tissue regeneration of the trachea in a rabbit model of tracheostomy. Twenty rabbits were randomized into 2 groups. Animals in the control group underwent surgical tracheostomy only, and animals in the AHAM group underwent surgical tracheostomy and received an AHAM graft that covered the defect site. We examined tissues at the site of tracheostomy 60 days after surgery by histological analysis with haematoxylin and eosin, Movat's pentachrome stain and immunohistochemistry by analysis with antiaggrecan antibodies. The average perimeter and area of the defect 60 days after surgery were smaller in animals in the control group than in the AHAM group (p = .011 and p = .011, respectively). Histological analysis of AHAM group revealed neovascularization, islands of immature cartilage, pseudostratified ciliated epithelium. and connective tissue at the site of AHAM engraftment, whereas only pseudostratified ciliated epithelium and connective tissue were observed at the defect site in tissues of animals in the control group. Regeneration of islands of immature cartilage tissue with hyaline pattern and pseudostratified ciliated epithelium were confirmed by immunohistochemistry analysis. These results indicate that AHAM engraftment could facilitate neovascularization and regeneration of immature cartilage in a model of tracheal injury. Its use may lower the risk of post-operative complications including stenosis of trachea.

Reconstruction of defects of the trachea

The trachea has a complex anatomy to fulfill its tasks. Its unique fibro-cartilaginous structure maintains an open conduit during respiration, and provides vertical elasticity for deglutition, mobility of the neck and speech. Blood vessels pierce the intercartilaginous ligaments to perfuse the ciliated epithelium, which ensures effective mucociliary clearance. Removal of a tracheal segment affected by benign or malignant disease requires airtight restoration of the continuity of the tube. When direct approximation of both tracheal ends is no longer feasible, a reconstruction is needed. This may occur in recurrent short-segment defects in a scarred environment, or in defects comprising more than half the length of the trachea. The resulting gap must be filled with vascularized tissue that restores the mucosal lining and supports the semi-rigid, semi-flexible framework of the trachea. For long-segment or circular defects, restoration of this unique biomechanical profile becomes even more important. Due to the inherent difficulty of creating such a tube, a tracheostomy or palliative stenting are often preferred over permanent reconstruction. To significantly improve and sustain quality of life of these patients, surgeons proposed innovative strategies for complex tracheal repair. In this review, we provide an overview of current clinical applications of tracheal repair using autologous and allogenic tissues. We look at recent advances in the field of tissue engineering, and the areas for improvement of these first human applications. Lastly, we highlight the focus of our research, in an effort to contribute to the development of optimized tracheal reconstructive techniques.

One-stage reconstruction of tracheal defects with the medial femoral condyle corticoperiosteal-cutaneous free flap

BACKGROUND

The demanding anatomic and mechanical requirements make the reconstruction of long tracheal defects challenging. Multiple attempts at replacing tracheal segments are described, including the use of autologous, allogeneic, and synthetic tissues. However, the multilayer structure of the trachea and its function as a conduit for air had generally resulted in the use of nonvascularized tissue and/or multistage procedures.

METHODS

The authors report on a 1-stage autologous reconstruction using local skin flaps for inner lining and a free medial femoral condyle corticoperiosteal-cutaneous (FCCPC) flap for the remaining layers. The skin island directly located over the FCCPC flap serves as an external coverage of the tracheal reconstruction.

RESULTS

Within the follow-up, the reconstructed trachea has retained its shape, diameter, and airway function. No notable stenosis or instability was observed.

CONCLUSION

This concept combines ideal biological and mechanical tissue properties, offering the potential to meet the reconstructive requirements for extended tracheal defects. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1870-1873, 2016.

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.

Current concepts in tracheal reconstruction

PURPOSE OF REVIEW

Many patients require tracheal reconstruction either for tracheal stenosis/malacia or following tumor extirpation. However, such patients can be debilitated following failed conventional treatments. Recent advances in tissue engineering and vascularized composite grafts are accelerating the field of tracheal reconstruction. This article reviews new clinical concepts for tracheal reconstruction.

RECENT FINDINGS

Novel treatments include composite autografts, allografts, chimeric autografts and allografts, tissue-engineered grafts, prosthetic scaffolds, and the use of free-tissue vascularized carriers.

SUMMARY

New procedures for tracheal reconstruction hold much promise for treating difficult tracheal disorders and improving the quality of life for affected patients. Many of the techniques reviewed herein are single case series and require further investigation and validation.

[Pedicled supraclavicular osteocutan island flap for tracheostoma closure]

Authors present a case of a 52-year-old female patient, who underwent an emergency tracheostomy due to life threatening dyspnoea caused by an external compression of a large goiter. Total thyreoidectomy needed to be carried out later, too. Since the atypical tracheostomy did not close spontaneously a reconstruction was planned. A part of the anterior wall of the trachea needed to be replaced, which was done by an osteocutaneous flap on raised on the supraclavicular artery. An island on the artery was harvested with a thin bone chip taken from the coracoid process of the clavicle, which was rotated into the defect then. The bone chip was sutured to the trachea wall and the donor site was closed primarily. Having reviewed the literature the authors propose the application of this flap in a wide range of cases. The advantages of this flap are the satisfactory functional and cosmetic results, as well as the fact that the donor site does not need skin grafting.

Development of a 3D bellows tracheal graft: mechanical behavior analysis, fabrication and an in vivo feasibility study

Artificial tracheal grafts should have not only enough compressive strength to maintain an open tracheal lumen, but also sufficient flexibility for stable mechanical behavior, similar to the native trachea at the implant site. In this study, we developed a new 3D artificial tracheal graft using a bellows design for considering its mechanical behavior. To investigate the mechanical behavior of the bellows structure, finite element method (FEM) analysis in terms of longitudinal tension/compression, bending and radial compression was conducted. The bellows structure was then compared with the cylinder structure generally used for artificial tracheal grafts. The FEM analysis showed that the bellows had outstanding flexibility in longitudinal tension/compression and bending. Moreover, the bellows kept the lumen open without severe luminal deformation in comparison with the cylinder structure. A three-dimensional artificial tracheal graft with a bellows design was fabricated using indirect solid freeform fabrication technology, and the actual mechanical test was conducted to investigate the actual mechanical behavior of the bellows graft. The fabricated bellows graft was then applied to segmental tracheal reconstruction in a rabbit model to assess its applicability. The bellows graft was completely incorporated into newly regenerated connective tissue and no obstruction at the implanted site was observed for up to 8 weeks after implantation. The data suggested that the developed bellows tracheal graft could be a promising alternative for tracheal reconstruction.