ClinicalTrials.gov; No.: NCT02013700; URL: www.clinicaltrials.gov.

Idiopathic pulmonary fibrosis (IPF) is a progressive, debilitating, and fatal lung disease characterized by interstitial fibrosis with decreasing lung volumes and hypoxemic respiratory failure. The prognosis for patients with IPF is poor and the quest to find effective therapies has been unsuccessful. Despite several clinical trials over the past decade, there are no U.S. Food and Drug Administration-approved treatments for patients with IPF and thus no standard of care. In terms of pathogenesis, IPF is characterized by alveolar epithelial cell injury and activation with interstitial inflammation, fibroblast proliferation with extracellular matrix collagen deposition, and loss of lung function. Because mesenchymal stem cells (MSCs) home to sites of injury, inhibit inflammation, and contribute to epithelial tissue repair, their use has been suggested as a therapy for the treatment of IPF. MSCs have potential as a novel therapeutic agent in multiple diseases and they have been safely administered in a number of clinical trials. Some, but not all, preclinical studies in animal models of lung fibrosis suggest that MSCs might be effective in the treatment of IPF. Given the safety and ease of MSC administration in other patient populations, the results in preclinical animal models of IPF, and the major need for novel therapeutic options in this devastating disease, we propose that carefully designed clinical trials of MSCs for the treatment of patients with IPF are appropriate. Establishing safety in the setting of IPF is the first priority in early clinical trials followed by clinical and biological measures of efficacy.

The observation that pulmonary inflammatory lesions and bleomycin (BLM)-induced pulmonary fibrosis spontaneously resolve in young mice, while remaining irreversible in aged mice, suggests that impairment of pulmonary regeneration and repair is associated with aging. Since mesenchymal stem cells (MSCs) may promote repair following injury, we postulated that differences in MSCs from aged mice may underlie post-injury fibrosis in aging. The potential for young-donor MSCs to inhibit BLM-induced pulmonary fibrosis in aged male mice (>22 months) has not been studied. Adipose-derived MSCs (ASCs) from young (4-month) and old (22-month) male mice were infused 1-day following intratracheal BLM administration. At 21-day sacrifice, aged BLM mice demonstrated lung fibrosis by Ashcroft score, collagen content, and αv-integrin mRNA expression. Lung tissue from aged BLM mice receiving young ASCs exhibited decreased fibrosis, matrix metalloproteinase (MMP)-2 activity, oxidative stress, and markers of apoptosis vs. BLM controls. Lung mRNA expression of TNFα was also decreased in aged BLM mice receiving young-donor ASCs vs. BLM controls. In contrast, old-donor ASC treatment in aged BLM mice did not reduce fibrosis and related markers. On examination of the cells, young-donor ASCs had decreased mRNA expression of MMP-2, insulin-like growth factor receptor, and AKT activation compared to old-donor ASCs. These results show that the BLM-induced pulmonary fibrosis in aged mice could be blocked by young-donor ASCs and that the mechanisms involve changes in collagen turnover and markers of inflammation.

Recently, we identified a lung adenocarcinoma signature that segregated tumors into three clades distinguished by histological invasiveness. Among the genes differentially expressed was the type II transforming growth factor-b receptor (TGFbRII), which was lower in adenocarcinoma mixed subtype and solid invasive subtype tumors compared with bronchioloalveolar carcinoma. We used a tumor cell invasion system to identify the chemokine CCL5 (RANTES, regulated on activation, normal T-cell expressed and presumably secreted) as a potential downstream mediator of TGF-b signaling important for lung adenocarcinoma invasion. We specifically hypothesized that RANTES is required for lung cancer invasion and progression in TGFbRII-repressed cells. We examined invasion in TGFbRII-deficient cells treated with two inhibitors of RANTES activity, Met-RANTES and a CCR5 receptor-blocking antibody. Both treatments blocked invasion induced by TGFbRII knockdown. In addition, we examined the clinical relevance of the RANTES-CCR5 pathway by establishing an association of RANTES and CCR5 immunostaining with invasion and outcome in human lung adenocarcinoma specimens. Moderate or high expression of both RANTES and CCR5 was associated with an increased risk for death, P ¼ 0.014 and 0.002, respectively. In conclusion, our studies indicate RANTES signaling is required for invasion in TGFbRIIdeficient cells and suggest a role for CCR5 inhibition in lung adenocarcinoma prevention and treatment.

The histological distinction between bronchioloalveolar carcinoma (BAC) and other adenocarcinomas is tissue invasion. The clinical importance of lung adenocarcinoma invasion is supported by several recent studies indicating that the risk of death in non-mucinous BAC is significantly lower than that of pure invasive tumors and in tumors with greater than 0.6 cm of fibrosis or linear invasion. Using microarray gene expression profiling of human tumors, dysregulation of transforming growth factor-ß (TGF-ß) signaling was identified as an important mediator of tumor invasion. Subsequent studies showed that the CC chemokine RANTES (Regulated on Activation, Normal T-cell Expressed, and presumably Secreted) was upregulated in invasive tumors and was required for invasion in cells with repressed levels of the TGF-ß type II receptor. Taken together, these studies illustrate how information gained from global expression profiling of tumors can be used to identify key pathways and genes mediating tumor growth, invasion, and metastasis.