Mesenchyme-free expansion and transplantation of adult alveolar progenitor cells: steps toward cell-based regenerative therapies

Abstract

Alveolar type-2 (AT2) cells are necessary for the lung’s regenerative response to epithelial insults such as influenza. However, current methods to expand these cells rely on mesenchymal co-culture, complicating the possibility of transplantation following acute injury. Here we developed several mesenchyme-free culture conditions that promote growth of murine AT2 organoids. Transplanting dissociated AT2 organoids into influenza-infected mice demonstrated that organoids engraft and either proliferate as AT2 cells or unexpectedly adopt a basal cell-like fate associated with maladaptive regeneration. Alternatively, transplanted primary AT2 cells also robustly engraft, maintaining their AT2 lineage while replenishing the alveolar type-1 (AT1) cell population in the epithelium. Importantly, pulse oximetry revealed significant increase in blood-oxygen saturation in primary AT2 recipients, indicating that transplanted cells also confer increased pulmonary function after influenza. We further demonstrated that both acid installation and bleomycin injury models are also amenable to AT2 transplantation. These studies provide additional methods to study AT2 progenitor potential, while serving as proof-of-principle for adoptive transfer of alveolar progenitors in potential therapeutic applications.

Rho-Kinase 1/2 Inhibition Prevents Transforming Growth Factor-β-Induced Effects on Pulmonary Remodeling and Repair

“…Furthermore, functional alterations in the FGF signaling pathway were observed. Fibroblast growth factors (FGFs) are members of the heparin-binding growth factor family that are often involved in morphogenesis and wound repair and FGF signaling dysregulations is implicated in many disorders (Ornitz and Itoh, 2015;Fehrenbach et al, 2017;Ohgiya et al, 2017;Plikus et al, 2017;Shiraishi et al, 2019;Weiner et al, 2019). FGF2 has attracted increasing attention in lung biology recently and is reported as an important factor in airway remodeling by increasing the deposition of proteoglycans resulting in bronchial hyperresponsiveness in asthmatic airways (Kim et al, 2018).…”

Regeneration of the pulmonary vascular endothelium after viral pneumonia requires COUP-TF2

“…Lungs were harvested from mice, and single-cell suspensions were prepared as previously described ( 82 ). Briefly, the lungs were thoroughly perfused with cold PBS via the left atrium to remove residual blood in the vasculature.…”

Orthotopic Transplantation and Engraftment of Human Induced Pluripotent Stem Cell-Derived Alveolar Progenitor Cells into Murine Lungs

“…Similar xenotransplantation of iPSC-derived human pancreatic β cells has also been recently demonstrated 6 , as has transplantation of human intestinal organoids 7 . In the lung, one group recently demonstrated successful engraftment of human stem cell-derived airway epithelial cells 8 , and another group achieved engraftment of primary (donor lung) derived type 2 pneumocytes (AT2s) 9 but to the best of our knowledge successful engraftment of human iPSC-derived alveolar progenitor cells (AT2s), has not been demonstrated.…”

“…We have previously demonstrated successful syngeneic engraftment of murine type 2 cells via intranasal inhalation after various injurious stimuli (influenza, bleomycin, acid instillation) 9 . Assuming that human cells would be immediately rejected upon transplant into immunocompetent animals, we administered the chemotherapeutic agent bleomycin to NSG mice 3 followed by orthotopic iPSC-derived lung/alveolar progenitor cell transplantation 10 days later.…”