Combined respiratory epithelial cell and gene therapy for amelioration of respiratory symptoms in children with Junctional Epidermolysis Bullosa
Lay summary
Epidermolysis Bullosa (EB) is a genetic disorder where patients suffer from extremely fragile surface tissues which painfully blister and scar with minimal trauma. It predominantly affects the external skin but the voice box and windpipe is significantly affected in some patients.
Treatment options for airway EB are very limited and often affected individuals will have difficulty in swallowing and gradually worsening breathing difficulties from airway scarring – eventual airway blockage creates the need for a tracheostomy (surgery where a small opening is made into the windpipe and a plastic tube is placed to allow airflow in and out).
Skin and airway lining research over the last two decades has identified many parallels; recent encouraging clinical case outcomes using gene-corrected skin grafts have therefore highlighted the possibility of delivering gene-corrected airway cells to cure airway disease. The work here aims to deliver laboratory-based tools to model EB airway disease, as well as to use lentiviral gene editing tools to correct EB-affected airway lining.
Scientific Summary
The effects of Epidermolysis Bullosa (EB) in the airway are heterogenous and the full extent of airway involvement remains unknown. In patients that suffer significant morbidity and mortality as a result of epithelial disease in the larynx and trachea, the most common mutation is in the LAMA3 gene, encoding the alpha3 chain of the laminin protein. Leveraging advances in the ability to expand airway epithelial stem/progenitor cells, this proposal aims to better characterise the airway epithelium from patients with airway EB and to develop autologous LAMA3 gene-edited airway epithelial cells as a potential curative approach.
Lay summary of results
In the first phase of their research, scientists focused on understanding the specific needs of EB patients referred to the Ear, Nose, and Throat department at GOSH. The study included 15 patients, both male and female, with an average age of just over 9 months at the time of referral. Among these patients, various EB subtypes were identified, with Junctional Epidermolysis Bullosa-Simplex (JEB-S) being the most common. Genetic analysis of this patient group revealed that nine out of 14 patients had pathogenic variants in one specific gene, LAMA3, suggesting that this gene has a particular tendency to lead to airway problems.
The research team successfully established cell cultures from airway biopsies from four patients with ‘airway EB’, allowing them to study the cells in the laboratory. They found that there was a lack of LAMA3 gene and protein expression in the cells in culture, and that the cells failed to adhere to plastic culture dishes as well as cells from non-EB donors. This suggests that the cell-based model is useful for further studying airway EB, and could be used to test potential therapies.
Building upon the insights gained from Aim 1, the research team then developed lentiviral vectors to deliver LAMA3 to the airway epithelial cells that were grown in cell culture. Application of the LAMA3 vector to airway EB patient cells led to a significant increase in LAMA3 RNA and protein expression. Most importantly, the corrected airway EB patient airway cells exhibited improved cell attachment, and were comparable to non-EB donor cells. This discovery suggests that therapeutic correction of LAMA3 expression could potentially address the cell adhesion defects for some airway EB patients.
To take the research a step further, the scientists would need to be able to take the corrected cells from culture and transplant them back to the airways. However, unlike for skin grafts, there is not currently a surgical method that would allow this to happen while maintaining patent airways. As such, the team tested tested epithelial cell engraftment using a rabbit airway surgery model. They isolated rabbit airway basal cells and grew them in cell culture conditions similar to those used for the EB patients previously, then developed customized 3D-printed stents designed to support tracheal epithelial cell grafts. Post-surgery analysis revealed successful engraftment of cultured cells in the rabbit trachea. Importantly, this opens the door to the potential for ex vivo-manipulated autologous cells to thrive post-transplantation in a clinically relevant setting.
The results of this study offer hope that in the future it will be possible to combine cell therapy and gene therapy to create a new solution for patients with airway manifestations of EB. The progress made in understanding the genetic basis of airway EB, developing gene-correction techniques, and successfully engrafting cultured cells in an animal model that is surgically similar to humans underscores the potential for transformative therapies. The next steps in this study will be to fine-tune the lentiviral vectors to be suitable for use in patients, and to further optimize the efficiency and reproducibility of cell transplantation.
Publications
Lau et al. Lentiviral expression of wild-type LAMA3A restores cell adhesion in airway basal cells from children with epidermolysis bullosa. Molecular Therapy (2024).
