Phase I/IIa Clinical Trial of Human Umbilical Cord Mesenchymal Stem Cell Injection in the Treatment of Idiopathic Pulmonary Fibrosis (IPF)

Main purpose -To explore the safety and tolerance of human umbilical cord mesenchymal stem cells in the treatment of idiopathic pulmonary fibrosis (IPF). Secondary purpose * To explore the preliminary efficacy of human umbilical cord mesenchymal stem cells in the treatment of idiopathic pulmonary fibrosis (IPF), and to recommend the appropriate dose of cell therapy for subsequent clinical studies. * To explore the immunogenicity of human umbilical cord mesenchymal stem cell injection in the treatment of idiopathic pulmonary fibrosis (IPF). This study adopts a clinical research design of multi center, single dose and increasing dose. 18 qualified IPF subjects will be included in this study.