CD4 and pulmonary emphysema: Figure 2b shows alterations in the lymphocyte in the spleen by hUC-MSCs in mice with PPE-induced emphysema. We observed that CD4+ lymphocytes were significantly decreased by PPE; however, the decreasing level was significantly increased by a high concentration of hUC-MSCs (p < 0.05). We did not observe a significant change in CD4+ CD25+ cells or regulatory T (Treg) cells in the spleen.