Curative Treatment for COPD Based on Differentiation Induction by Synthetic Retinoid Am80 and Development of Inhalation Powder

Chronic obstructive pulmonary disease (COPD) is characterized by chronic bronchitis and emphysema, and current drug treatments is limited to symptomatic therapy. Thus, there is an urgent need for development of new treatments to repair alveolar destruction. To regenerate the destroyed alveoli, we focused on the differentiation of alveolar epithelial progenitor cells into type I or type II alveolar epithelial cells that constitute the alveoli. Our concept of alveolar regeneration therapy is based on developing a drug delivery system (DDS) and dry powder inhalation that can efficiently deliver new alveolar regeneration drugs, which were discovered using human alveolar epithelial progenitor cells, to stem cells present on the surface of the alveoli of COPD patients, thereby inducing alveolar regeneration. This review article summarizes our data on the discovery of the synthetic retinoid Am80 as a candidate drug for alveolar regeneration, the construction of a DDS that utilizes a biological mechanism that enhances its effect on alveolar regeneration, and the formulation design of a dry powder inhalation.