Ann. N.Y. Acad. Sci. ISSN 0077-8923 ANNALS OF THE NEW YORK ACADEMY OF SCIENCES Issue: Evolving Challenges in Promoting Cardiovascular Health Umbilical cord blood for cardiovascular cell therapy: from promise to fact Santiago Roura, 1 Josep-Maria Pujal, 1 and Antoni Bayes-Genis 1,2,3,4 1 ICREC Research Group, Health Sciences Research Institute Germans Trias i Pujol (IGTP), Barcelona, Spain. 2 Cardiology Service, University Hospital Germans Trias i Pujol, Barcelona, Spain. 3 Department of Medicine, Autonomous University Barcelona, Spain. 4 Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain Address for correspondence: Antoni Bayes-Genis, M.D., Ph.D., FESC, ICREC (Heart Failure and Cardiac Regeneration) Research Group, Cardiology Service, University Hospital Germans Trias i Pujol, Crta. Canyet, s/n, 08916 Badalona, Barcelona, Spain. abayes.germanstrias@gencat.cat Endothelial recovery and cell replacement are therapeutic challenges for cardiovascular medicine. Initially employed in the treatment of blood malignancies due to its high concentration of hematological precursors, umbilical cord blood (UCB) is now a non-controversial and accepted source of both hematopoietic and non-hematopoietic progenitors for a variety of emerging cell therapies in clinical trials. Here, we review the current therapeutic potential of UCB, focusing in recent evidence demonstrating the ability of UCB-derived mesenchymal stem cells to differentiate into the endothelial lineage and to develop new vasculature in vivo. Keywords: cardiovascular diseases; umbilical cord blood; mesenchymal stem cell Introduction Endothelial recovery and cell replacement are paramount therapeutic challenges for cardiovascu- lar regenerative medicine. 1 Beyond pharmacologi- cal or surgical intervention, stem cell–based thera- pies are promising for regenerating injured human tissues through the promotion of vascular growth and repair. 2 The acquisition of phenotypic and func- tional characteristics of the endothelial lineage has been reported for progenitor cells isolated from bone marrow 3,4 and adipose tissue. 5 Umbilical cord blood (UCB) is currently emerging as a valuable stem cell source. 6 The absence of ethical concerns and unlimited cell supply due to the continuous growth of the world population, which is expected to remain at a constant annual level of 134 million births according to U.S. Census Bureau estimations, explain the increasing interest in using UCB for a variety of clinical applications. In addition, UCB can be safely obtained and cryopreserved in either pub- lic or private banks without a loss of cell viability and has a lower risk of transmitting viral infections and somatic mutations than adult tissues. 7 Here, we review the therapeutic potential of UCB in a spectrum of human disorders, including car- diovascular diseases, focusing on recent evidence that demonstrates the ability of UCB-derived mes- enchymal stem cells (MSCs) to differentiate into the endothelial lineage and to develop new microvascu- lature in vivo. Clinical applications of UCB UCB was first employed as an alternative source of hematopoietic (CD34 + ) progenitors in the treat- ment of autologous pediatric hematological malig- nancies. 8 Given that HLA-matching requirements for transplantation are not as strict as for other well- known hematopoietic stem cell sources, the use of UCB has been gaining acceptance for adult patients lacking matched (related or unrelated) bone marrow donors. 9 UCB is a noncontroversial and accepted stem cell source for cell therapy, and it has been ex- tended to defective immune system reconstitution 10 and the correction of congenital hematological ab- normalities. 11 The most marked limitation in the use of UCB is its low progenitor cell concentration. Thus, doi: 10.1111/j.1749-6632.2012.06515.x 66 Ann. N.Y. Acad. Sci. 1254 (2012) 66–70 c  2012 New York Academy of Sciences.