Alveolar Type II (AT2) Cell-Derived Exosomes

Overview

Parent Cell: Akira Alveolar Type 2 Cells differentiated from UCT-WJ-MSCs | Surfactant-associated proteins and alveolar repair growth factors for lung repair and regeneration

What Are Exosomes?

Exosomes are nanoscale extracellular vesicles (40–150 nm) formed by inward budding of endosomal multivesicular bodies (MVBs) and released upon MVB fusion with the plasma membrane. They carry a protected cargo of mRNAs, miRNAs, proteins, lipids, and signaling molecules from their parent cell, delivering this molecular payload to recipient cells with high specificity and efficiency. Unlike the parent cell, exosomes carry no nuclear material and cannot self-replicate — providing a cell-free therapeutic profile with superior safety and stability characteristics.

The Akira Lung Exosomes are derived from Alveolar Type II (AT2) cells produced by directed differentiation of UCT-WJ-MSCs using a defined lung progenitor specification protocol employing Wnt inhibition, BMP4 and FGF10 signaling to generate anterior foregut endoderm, followed by further specification to NKX2.1+ lung progenitors and terminal AT2 differentiation. AT2 cells are the stem cells of the alveolar epithelium — responsible for surfactant production, alveolar repair, and type I cell replenishment.

Lung exosomes from AT2 cells are enriched with surfactant-associated proteins (SP-A, SP-D) and alveolar repair growth factors (KGF, HGF, EGF). KGF (FGF-7) is the dominant alveolar epithelial repair factor, specifically stimulating AT2 cell proliferation and type I alveolar cell differentiation. The anti-inflammatory miRNA cargo addresses the acute and chronic pulmonary inflammatory states that underlie ARDS, IPF, and COVID-19 lung injury.^[1]

Mechanism of Action

Alveolar Epithelial Repair (KGF/EGF Pathway): KGF (FGF-7) is the most potent known growth factor for alveolar type II cell proliferation, signaling through FGFR2b. In damaged alveoli, KGF cargo drives remaining AT2 cells to proliferate and differentiate into type I alveolar cells, restoring the gas exchange surface. EGF and HGF provide complementary alveolar epithelial mitogenic signals through EGFR and c-Met respectively.

Pulmonary Inflammation Resolution: miR-146a suppresses NF-κB in alveolar macrophages, reducing IL-1β, TNF-α, and IL-6 in the inflamed lung. miR-223 targets and suppresses IL-6 directly. miR-21 suppresses PTEN in epithelial cells, promoting survival under inflammatory conditions. SP-A and SP-D in the secretome modulate alveolar macrophage function and pattern recognition receptor signaling.

Pulmonary Fibrosis Reduction: IPF (idiopathic pulmonary fibrosis) is driven by TGF-β1-mediated myofibroblast activation and collagen deposition replacing normal alveolar architecture. AT2-derived exosomes carry miR-127 and anti-fibrotic HGF that antagonize TGF-β1-driven fibroblast activation. miR-21 paradoxically exhibits both pro- and anti-fibrotic properties depending on cellular context — the AT2 lineage cargo is enriched for the anti-fibrotic regulatory milieu.

Surfactant System Support: SP-A and SP-D from the AT2 secretome perform pattern recognition and immune modulation in the alveolar space, regulating macrophage activation and reducing pathogen-driven inflammation. Surfactant proteins maintain alveolar surface tension, preventing alveolar collapse in conditions of surfactant deficiency (neonatal RDS, ARDS). ABCA3-associated cargo supports lipid transport for surfactant phospholipid production.^[2]

Key Molecular Cargo

Therapeutic Applications

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Clinical & Preclinical Evidence

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