Lentiviral expression of wildtype LAMA3A restores cell adhesion in airway basal cells from children with epidermolysis bullosa
The hallmark of epidermolysis bullosa (EB) is the fragile attachment of epithelia to underlying tissues due to genetic variants in genes involved in cell adhesion. A variety of epithelial surfaces can be affected, and EB patients who develop airway involvement suffer from a high degree of morbidity and mortality from laryngotracheal stenosis. Here, we describe 15 EB patients that were treated in the Ear, Nose and Throat department of a tertiary pediatric hospital linked to the United Kingdom's National EB unit between 1992 and 2023. Investigation of the underlying genotypic status revealed that variants in LAMA3 were common in EB patients managed with airway complications (9/14 patients where genotype was available). Since LAMA3 encodes a subunit of the laminin-332 heterotrimeric extracellular matrix protein complex and is expressed by airway basal epithelial stem cells, we investigated the possibility of correcting LAMA3 in EB patient basal cell cultures. Airway basal cell cultures initiated from EB patients with variants affecting LAMA3 demonstrated fragile adherence to culture flasks but were otherwise expanded similarly to non-EB patient cell cultures. For genetic modification, we generated a lentiviral vector containing LAMA3A under the control of a constitutively active promoter sequence. In vitro transduction of primary EB patient-derived basal cell cultures restored cell attachment to levels comparable to a healthy control donor culture. Transduced cells could be expanded extensively in cell culture, suggesting their potential as an airway cell therapy for EB. We anticipate that our proof-of-concept data will be a starting point for translational combined cell and gene therapy for this rare patient group. Overall design: Non-transduced controls vs LAMA3-transduced cells. Replicates are independent transductions from a single EB patient.