[Retinoic acid and regeneration therapy of the lung diseases]

Retinoic acid is the bioactive metabolite of vitamin A and considerable evidence implicates retinoic acid as important signaling molecule during normal lung development and retinoid signaling elements, such as receptors and binding proteins have been described in the developing lung. Alveolization, or the formation of alveoli during lung development, is essentially completed in the neonatal period, and little neo-alveolization occurs in the adult lung. Recently, several studies have shown that retinoic acid is effective in promoting alveolization in neonatal rats, in adult rats with elastase-induced emphysema. However, the exact mechanism governing this regeneration is still unknown. Recent advanced technologies will clarify the role of retinoic acid in alveolization and even how alveolization occurs, leading to regeneration therapy for the devastating lung diseases, such as emphysema and fibrotic disorders.