The Role of Bone Marrow-Derived Adult Stem Cells in a Transgenic Mouse Model of Allergic Asthma

Background: Asthmatic airway remodeling is an abnormal injury/repair process of the small airways caused by chronic inflammation in which the quantities of multiple cells increase dramatically. However, the origin of these proliferative cells is still undetermined. Objective: The aim of this study was to examine whether bone marrow (BM)-derived adult stem cells are responsible for the proliferative cells in asthmatic airway remodeling. Methods: Adult mice were durably engrafted with BM isolated from green fluorescent protein (GFP) transgenic mice. Using GFP BM chimera mice, an ovalbumin (OVA)-induced chronic asthma mouse model was established. The distribution of BM-derived GFP+ cells in the lungs of chronic asthma mice was detected by fluorescence microscopy. The phenotype of BM-derived GFP+ cells in the lung tissues of chronic asthma mice was analyzed by flow cytometry. Results: BM chimera mice were successfully generated, with no detectable radioactive inflammation observed. Using BM chimera mice, we established a mouse model of chronic asthma characterized by a significant increase in the thickness of the airway subepithelial basement membrane and smooth muscle layers. OVA treatment caused many GFP+ cells to appear at sites of small airway inflammation. The extravascular localization of some GFP+ cells and their morphology were not consistent with leukocytes. Flow cytometric analysis of lung cells revealed a significant increase in type I collagen (Col I)+GFP+ cells and α-smooth muscle actin (α-SMA)+GFP+ cells in OVA-treated GFP BM chimera mice. Conclusions: Considerable numbers of Col I- and α-SMA-producing cells originated from BM in the lung tissues of mice with OVA-induced chronic asthma.