title: Mechanisms of cellular therapy in respiratory diseases.
abstract: OBJECTIVE
  Stem cells present a variety of clinical implications in the lungs. According to their origin, these cells can be divided into embryonic and adult stem cells; however, due to the important ethical and safety limitations that are involved in the embryonic stem cell use, most studies have chosen to focus on adult stem cell therapy. This article aims to present and clarify the recent advances in the field of stem cell biology, as well as to highlight the effects of mesenchymal stem cell (MSC) therapy in the context of acute lung injury/acute respiratory distress syndrome and chronic disorders such as lung fibrosis and chronic obstructive pulmonary disease.
  
  
  METHODS
  For this purpose, we performed a critical review of adult stem cell therapies, covering the main clinical and experimental studies published in Pubmed databases in the past 11 years. Different characteristics were extracted from these articles, such as: the experimental model, strain, cellular type and administration route used as well as the positive or negative effects obtained.
  
  
  RESULTS
  There is evidence for beneficial effects of MSC on lung development, repair, and remodeling. The engraftment in the injured lung does not occur easily, but several studies report that paracrine factors can be effective in reducing inflammation and promoting tissue repair. MSC releases several growth factors and anti-inflammatory cytokines that regulate endothelial and epithelial permeability and reduce the severity of inflammation.
  
  
  CONCLUSIONS
  A better understanding of the mechanisms that control cell division and differentiation, as well as of their paracrine effects, is required to enable the optimal use of bone marrow-derived stem cell therapy to treat human respiratory diseases.
authors.affiliation: Laboratório de Investigação Pulmonar, Centro de Ciências da Saúde, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Avenida Carlos Chagas Filho, s/n, Bloco G-014, Ilha do Fundão, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: Soraia C
authors.initials: SC
authors.lastname: Abreu
authors.forename: Mariana A
authors.initials: MA
authors.lastname: Antunes
authors.forename: Paolo
authors.initials: P
authors.lastname: Pelosi
authors.forename: Marcelo M
authors.initials: MM
authors.lastname: Morales
authors.forename: Patricia R M
authors.initials: PR
authors.lastname: Rocco
mesh_terms: D053687:Adult Stem Cells / Q000378:metabolism* / Q000637:transplantation*; D001854:Bone Marrow Cells; D005355:Fibrosis / Q000628:therapy; D006801:Humans; D008171:Lung Diseases / Q000628:therapy*; D045164:Mesenchymal Stem Cell Transplantation; D029424:Pulmonary Disease, Chronic Obstructive / Q000628:therapy; D012128:Respiratory Distress Syndrome / Q000628:therapy