Toward combined cell and gene therapy for airway epidermolysis bullosa

Epidermolysis bullosa (EB) is a group of rare, inherited genetic diseases characterised by fragility and blistering of epithelial tissues. Airway involvement in EB is rare but affected patients experience a high burden of morbidity and mortality. EB airway disease involves granulation tissue formation and scarring of the larynx and trachea. As the disease progresses, airway stenosis (narrowing) ensues and necessitates a tracheostomy.

At Great Ormond Street Hospital, children with diagnoses of JEB-S (n=9) or JEB-LOC (n=4) were most commonly referred to ENT services. 10/15 patients had mutations in the LAMA3 gene, suggesting that variants in LAMA3 confer particular susceptibility to airway disease and thus represent targets for therapy. We developed a lentiviral vector to express wildtype LAMA3A in cultured primary EB patient human airway basal epithelial cells. Transduction restored LAMA3 expression, enabled appropriate cellular differentiation and restored the in vitro cell adhesion of EB basal cells to levels comparable to non-EB cells.

To progress towards clinical application, we envisage transplantation of LAMA3-transduced autologous cells to the airways. We developed a surgical transplantation model through short segment tracheal resection and primary anastomosis in New Zealand white rabbits, establishing autologous epithelial cell cultures for each animal. After transduction with a lentivirus for cell tracking, ZsGreen+ cells were sorted, expanded, seeded onto fibrin sheets and wrapped around bespoke 3D-printed soft elastomer composite tubular constructs before tracheal reimplantation. Engraftment of transplanted cells was found after 4 or 10 days, suggesting the viability of stent-based airway epithelial cell transplantation.