Pulmonary mechanics of papain emphysema in dogs

Unicentric study of cell therapy in chronic obstructive pulmonary disease/pulmonary emphysema

Within the chronic obstructive pulmonary disease (COPD) spectrum, lung emphysema presents, as a primarily histopathologic feature, the destruction of pulmonary parenchyma and, accordingly, an increase in the airflow obstruction distal to the terminal bronchiole. Notwithstanding the significant advances in prevention and treatment of symptoms, no effective or curative therapy has been accomplished. In this context, cellular therapy with stem cells (SCs) arises as a new therapeutic approach, with a wide application potential. The purpose of this study is to evaluate the safety of SCs infusion procedure in patients with advanced COPD (stage IV dyspnea). After selection, patients underwent clinical examination and received granulocyte colony-stimulating factor, immediately prior to the bone marrow harvest. The bone marrow mononuclear cells (BMMC) were isolated and infused into a peripheral vein. The 12-month follow-up showed a significant improvement in the quality of life, as well as a clinical stable condition, which suggest a change in the natural process of the disease. Therefore, the proposed methodology in this study for BMMC cell therapy in sufferers of advanced COPD was demonstrated to be free of significant adverse effects. Although a larger sample and a greater follow-up period are needed, it is possible to infer that BMMC cell therapy introduces an unprecedented change in the course or in the natural history of emphysema, inhibiting or slowing the progression of disease. This clinical trial was registered with ClinicalTrials.gov (NCT01110252) and was approved by the Brazilian National Committee of Ethics in Research (registration no. 14764, CONEP report 233/2009).

The influence of pulmonary receptors on respiratory drive in a rabbit model of pulmonary emphysema

We have observed that pulmonary rapidly adapting receptor activity is greater in emphysematous rats than in controls. Pulmonary receptor activity, if modified by lung disease, may produce an inappropriate drive to breathe which may be perceived as dyspnoea. To investigate the efferent (drive) component of this hypothesis respiratory drive (phrenic nerve activity) was recorded in a rabbit model of emphysema. Drive was measured as slope and peak height of phrenic nerve activity. Slope and peak height were greater in emphysematous rabbits than controls, by 28% and 34%, respectively. Block of slowly adapting pulmonary stretch receptors by inhaled sulphur dioxide (which left only rapidly adapting and C-fibre receptors active) decreased drive in control (slope: 38.89+/-2.29 to 24.09+/-1.26, P<0.01) but not emphysematous rabbits (slope: 49.92+/-4.11 to 54.51+/-5.28, NS). Subsequent vagotomy decreased drive in emphysematous rabbits (slope: 54.51+/-5.28 to 41.41+/-3.90, P<0.05) but not controls (24.09+/-1.26 to 23.07+/-1.84, NS). Increased rapidly adapting receptor activity may, in part, increase respiratory drive in emphysema. This vagal component is only part of the total increased drive which may be perceived as dyspnoea in man.