Versatile and Cross-Species Alveolar Type II Cell Isolation Using Humanized Monoclonal Antibody Upifitamab

Alveolar type 2 (AT2) cells are primary adult alveolar stem cells that maintain healthy alveoli. AT2 cell dysfunction is broadly linked to many lung pathologies from emphysema to fibrosis. Isolation of AT2 cells with high purity is therefore central to diagnostic studies, proteomics, transcriptomics and ex vivo experiments that can lead to future AT2 cellular therapies. Current markers for AT2 isolation exhibit various limitations from species-restrictions (e.g., mouse vs human) to limited AT2 specificity, which creates challenges for flow cytometric gating/sorting and application to magnetic-activated cell isolation. While underrepresented in the literature, these bottlenecks have made AT2 cell isolation inherently difficult and slowed AT2 cell research. Here we leverage surface protein-restricted transcriptomics to identify the sodium phosphate transporter NaPi2b (SLC34A2) as a highly specific AT2 cell marker optimally detected with the humanized monoclonal antibody upifitamab. Upifitamab-based labeling of AT2 cells is compatible with flow cytometric or magnetic-activated AT2 isolation and applies to both mouse and human AT2 cells, thus streamlining protocols and circumventing species-specific nuances. AT2 cells obtained with upifitamab can be cultured as organoids, in monolayers or differentiated to AT1 cells. This simplified AT2 isolation approach should overcome several current barriers while facilitating ex vivo studies on alveolar biology and related therapeutic developments.