Safety of human umbilical cord mesenchymal stem cells transplanted into rats by intramuscular injection  
Zhang Mei-rong, Zhang Xue-feng, Hu Jian-xia, Wang Li, Zhang Gui-zhi, Gao Hong, Miao Zhi-min, Wang Yan-gang
Chinese Journal of Tissue Engineering Research . 2010, (27): 4997 -5000 .  DOI: 10.3969/j.issn.1673-8225.2010.27.013