In rat models of <i>established</i> emphysema induced by cigarette smoke extract or the VEGF receptor antagonist SU5416, two-week lung administration of CDSO3 at 60 μg/kg from day 21 enabled: 68-79% recovery of exercise endurance and airspace enlargement/destruction; a 1.8-fold increase in proliferating cell nuclear antigen above healthy levels; normalization of cleaved caspase-3; restoration of HIF-1α; and a 1.3-fold increase in VEGF above healthy levels. The gene discussed is HIF1A; the disease is pulmonary emphysema.