hUCMSCs favor esophageal cancer growth in vivo. (A) HUCMSCs promoted the esophageal tumors formation in nude mice. The results were expressed as mean ± S.D. *P < 0.05, Eca109 + hUCMSCs versus Eca109. (B) HUCMSCs promoted the pre-established esophageal tumors growth in nude mice. *P < 0.05, Eca109, i.v. hUCMSCs versus Eca109. (C) On the 44th day after implantation, the mice were killed. Tumors formed by Eca109 cells admixed with hUCMSCs increased in blood vessel formation in gross analysis. (D) Lymph node metastasis was seen in the group that mixed Eca109 cells and hUCMSCs were injected.