Allogeneic umbilical cord-derived mesenchymal stem cell transplantation for treating chronic obstructive pulmonary disease: a pilot clinical study oleh Phuong Le Thi Bich, Ha Nguyen Thi, Hoang Dang Ngo Chau, Tien Phan Van, Quyet Do, Hung Dong Khac, Dong Le Van, Luc Nguyen Huy, Khan Mai Cong, Thang Ta Ba, Trung Do Minh, Ngoc Vu Bich, Nhat Truong Chau, Phuc Van Pham