Tissue-Engineered Larynx: Future Applications in Laryngeal Cancer

Advances in the Treatment of Dysphagia in Neurological Disorders: A Review of Current Evidence and Future Considerations

Dysphagia, which refers to difficult and/or disordered swallowing, is a common problem associated with various neurological diseases such as stroke, motor neuron diseases and neurodegenerative diseases. Traditionally, dysphagia treatments are either compensatory, which includes modifications of bolus texture or feeding posture, or rehabilitative, which includes behavioral exercises and sensory stimulation. Despite being widely adopted in clinical practice, recent views have challenged the clinical efficacy of these treatments due to the low level of evidence supported by mainly non-controlled studies. As such, with advancements in technology and scientific research methods, recent times have seen a surge in the development of novel dysphagia treatments and an increasing number of robust randomized controlled clinical trials. In this review, we will review the clinical evidence of several newly introduced treatments for dysphagia in the last two decades, including rehabilitative exercises, biofeedback, pharmacological treatments, neuromodulation treatments and soft robotics. Despite the recent improvements in the quality of evidence for the efficacy of dysphagia treatments, several critical issues, including heterogeneity in treatment regimens, long-term treatment effects, underlying mechanisms of some neuromodulation treatments, and the effects of these techniques in non-stroke dysphagia, remain to be addressed in future clinical trials.

GMP compliant isolation of mucosal epithelial cells and fibroblasts from biopsy samples for clinical tissue engineering

Engineered epithelial cell sheets for clinical replacement of non-functional upper aerodigestive tract mucosa are regulated as medicinal products and should be manufactured to the standards of good manufacturing practice (GMP). The current gold standard for growth of epithelial cells for research utilises growth arrested murine 3T3 J2 feeder layers, which are not available for use as a GMP compliant raw material. Using porcine mucosal tissue, we demonstrate a new method for obtaining and growing non-keratinised squamous epithelial cells and fibroblast cells from a single biopsy, replacing the 3T3 J2 with a growth arrested primary fibroblast feeder layer and using pooled Human Platelet lysate (HPL) as the media serum supplement to replace foetal bovine serum (FBS). The initial isolation of the cells was semi-automated using an Octodissociator and the resultant cell suspension cryopreservation for future use. When compared to the gold standard of 3T3 J2 and FBS containing medium there was no reduction in growth, viability, stem cell population or ability to differentiate to mature epithelial cells. Furthermore, this method was replicated with Human buccal tissue, providing cells of sufficient quality and number to create a tissue engineered sheet.

The past the present and the future of face transplantation

PURPOSE OF REVIEW

Face transplantation represents vascularized composite allotransplantation (VCA) organ and became one of the most rewarding reconstructive options for severely disfigured patients. This review summarizes the past, current and future challenges of face transplantation, based on our experience and literature reports.

RECENT FINDINGS

In 2005, first partial face transplantation was reported by French team. In 2008, we have performed the US first near-total face transplantation. Currently, more than 40 face transplant cases were reported worldwide. Based on the outcomes of our three patients and the literature reports, face transplantation improved aesthetics, function and the quality of life of face transplant patients. However, there are still many challenges encountered including the side effects of immunosuppressive protocols, the psychological and social problems as well as the financial challenges which need to be address in the near future to maintain face transplantation in the armamentarium of reconstructive surgery.

SUMMARY

Currently, feasibility of face transplantation was confirmed; however, the life-long immunosuppressive protocols bearing serious side effects are still required to prevent face rejection. Thus, for the future of face and other VCA, novel approaches of cell-based therapies or engineered scaffolds should be developed to make face transplantation safer.

The pig as a model for immunology research

The pig is an omnivorous, monogastric species with many advantages to serve as an animal model for human diseases. There are very high similarities to humans in anatomy and functions of the immune system, e g., the presence of tonsils, which are absent in rodents. The porcine immune system resembles man for more than 80% of analyzed parameters in contrast to the mouse with only about 10%. The pig can easily be bred, and there are less emotional problems to use them as experimental animals than dogs or monkeys. Indwelling cannulas in a vein or lymphatic vessel enable repetitive stress-free sampling. Meanwhile, there are many markers available to characterize immune cells. Lymphoid organs, their function, and their role in lymphocyte kinetics (proliferation and migration) are reviewed. For long-term experiments, minipigs (e.g., Göttingen minipig) are available. Pigs can be kept under gnotobiotic (germfree) conditions for some time after birth to study the effects of microbiota. The effects of probiotics can be tested on the gut immune system. The lung has been used for extracorporeal preservation and immune engineering. After genetic modifications are established, the pig is the best animal model for future xenotransplantation to reduce the problem of organ shortage for organ transplantation. Autotransplantation of particles of lymphnodes regenerates in the subcutaneous tissue. This is a model to treat secondary lymphedema patients. There are pigs with cystic fibrosis and severe combined immune deficiency available.

3D printing for tissue engineering in otolaryngology

Airway and other head and neck disorders affect hundreds of thousands of patients each year and most require surgical intervention. Among these, congenital deformity that affects newborns is particularly serious and can be life-threatening. In these cases, reconstructive surgery is resolutive but bears significant limitations, including the donor site morbidity and limited available tissue. In this context, tissue engineering represents a promising alternative approach for the surgical treatment of otolaryngologic disorders. In particular, 3D printing coupled with advanced imaging technologies offers the unique opportunity to reproduce the complex anatomy of native ear, nose, and throat, with its import in terms of functionality as well as aesthetics and the associated patient well-being. In this review, we provide a general overview of the main ear, nose and throat disorders and focus on the most recent scientific literature on 3D printing and bioprinting for their treatment.

Expression and clinical significance of miRNA-145 and miRNA-218 in laryngeal cancer

Expression of miRNA-145 and miRNA-218 in serum of patients with laryngeal cancer and the relationship between them and the clinicopathological parameters and prognosis were investigated. The clinical medical records of 132 patients with laryngeal cancer, who were admitted to Guangdong Second Provincial General Hospital from February 2009 to March 2014, were retrospectively analyzed and comprised the study group. The data of physical examinations of 56 healthy volunteers who took physical examinations in the same hospital comprised the control group. RT-qPCR was used to detect the expression levels of miRNA-145 and miRNA-218 in serum of the patients in the two groups. According to the relative expression levels of miRNA-145 and miRNA-218 in serum of the patients in the study group on the day when they left hospital, the study group was divided into the high expression group (n=73 patients) and the low expression group (n=59 patients). The patients received a 48-month follow-up visit and their survival condition was recorded and the Kaplan-Meier was used to carry out the survival analysis. The expression levels of miRNA-145 and miRNA-218 in serum of the patients in the study group were lower than those in the control group (P<0.05). The median survival time of the patients in the high expression group was 30 months while the median survival time of the patients in the low expression group was 26 months. The expression levels of miRNA-145 and miRNA-218 in serum of patients with laryngeal cancer decreased, the higher the expression levels of miRNA-145 and miRNA-218 in serum of patients with laryngeal cancer were, the better the prognosis was. miRNA-145 and miRNA-218 were used as indicators of assessing the prognosis of patients with laryngeal cancer.

Improving cellular migration in tissue-engineered laryngeal scaffolds

OBJECTIVE

To modify the non-porous surface membrane of a tissue-engineered laryngeal scaffold to allow effective cell entry.

METHODS

The mechanical properties, surface topography and chemistry of polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane were characterised. A laser technique introduced surface perforations. Micro computed tomography generated porosity data. Scaffolds were seeded with cells, investigated histologically and proliferation studied. Incubation and time effects were assessed.

RESULTS

Laser cutting perforated the polymer, connecting the substructure with the ex-scaffold environment and increasing porosity (porous, non-perforated = 87.9 per cent; porous, laser-perforated at intensities 3 = 96.4 per cent and 6 = 89.5 per cent). Cellular studies confirmed improved cell viability. Histology showed cells adherent to the scaffold surface and cells within perforations, and indicated that cells migrated into the scaffolds. After 15 days of incubation, scanning electron microscopy revealed an 11 per cent reduction in pore diameter, correlating with a decrease in Young's modulus.

CONCLUSION

Introducing surface perforations presents a viable method of improving polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane as a tissue-engineered scaffold.

Motor endplate-expressing cartilage-muscle implants for reconstruction of a denervated hemilarynx

OBJECTIVE

Tissue engineering of the larynx requires a complex, multiple tissue layer design. Additionally, spontaneous reinnervation of the larynx after recurrent laryngeal nerve (RLN) injury is often disorganized, resulting in subpar function. This study investigates use of tissue-engineered cartilage and motor endplate-expressing (MEE) tissue-engineered skeletal muscle implants for laryngeal reconstruction and the promotion of organized reinnervation after RLN injury.

METHODS

F344 rat primary muscle progenitor cells (MPCs) were isolated. Three-dimensional muscle constructs were created by encapsulating MPCs in type I oligomeric collagen under passive tension. Constructs were then cultured in differentiation medium (MPC control constructs) or induced to form motor endplates (MEE constructs) with neurotrophic agents. Three-dimensional cartilage constructs were created with adipose stem cells differentiated in chondrocyte medium. The muscle and cartilage constructs were implanted into surgically created myochondral defects in the F344 rat larynx with injured or intact (control) RLN. At 1-, 3-, and 6-month timepoints, videolaryngoscopy, electromyography (EMG), histology, and immunohistochemistry were used to assess outcomes.

RESULTS

At all timepoints, cartilage-muscle implants were well integrated into host tissue. Functionally, there was increased vocal fold adduction and EMG activity in nerve-injured rats treated with the MEE constructs when compared to those treated with the MPC control constructs. Motor endplate-expressing constructs had increased myofiber cross-sectional area compared to MPC control constructs.

CONCLUSION

Although our laboratory previously demonstrated that muscle and cartilage constructs could be used separately for hemilaryngeal reconstruction, this study suggests combining them with the modification of MEEs rather than MPCs, resulting in improved muscle recovery after recurrent laryngeal nerve injury.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:1293-1300, 2019.

[Regeneration - A New Therapeutic Dimension in Otorhinolaryngology]

Regeneration as a therapeutic priniciple and regenerative medicine in general are promising new strategies to add new therapeutic dimensions to our current treatment options. Today, reconstructive surgery, drugs and implants such as the cochlear implant can replace the functions of damaged tissues. In contrast, regenerative therapies aim at the replacement of the damaged tissues themselves while at the same time replacing their lost tissue function. In this review article new technologies such as 3D-bioprinting and the application of decellularised tissues as biomaterials are introduced and explained. A summary of current preclinical and clinical regenerative studies in otorhinolaryngology is complementing these basic aspects.