title: Formation of human myocardium in the rat heart from human embryonic stem cells.
abstract: Human embryonic stem cells (hESCs) offer the opportunity to replenish cells lost in the postinfarct heart. We explored whether human myocardium could be generated in rat hearts by injecting differentiated cardiac-enriched hESC progeny into the left ventricular wall of athymic rats. Although initial grafts were predominantly epithelial, noncardiac elements were lost over time, and grafts consisted predominantly of cardiomyocytes by 4 weeks. No teratomatous elements were observed. Engrafted cardiomyocytes were glycogen-rich and expressed expected cardiac markers including beta-myosin heavy chain, myosin light chain 2v, and atrial natriuretic factor. Heat-shock treatment improved graft size approximately threefold. The cardiac implants exhibited substantial angiogenesis, both recipient and graft derived. Importantly, there was greater proliferation in human cardiomyocytes than previously seen in rodent-derived cardiomyocytes: 14.4% of graft cardiomyocytes expressed the proliferation marker Ki-67, and 2.7% incorporated the thymidine analog BrdU 4 weeks after transplantation. This proliferation was associated with a sevenfold increase in graft size over the 4-week interval. Thus, hESCs can form human myocardium in the rat heart, permitting studies of human myocardial development and physiology and supporting the feasibility of their use in myocardial repair.
authors.affiliation: Department of Pathology, University of Washington, Seattle, WA 98109, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Laflamme
authors.forename: Joseph
authors.initials: J
authors.lastname: Gold
authors.forename: Chunhui
authors.initials: C
authors.lastname: Xu
authors.forename: Mohammad
authors.initials: M
authors.lastname: Hassanipour
authors.forename: Elen
authors.initials: E
authors.lastname: Rosler
authors.forename: Shailaja
authors.initials: S
authors.lastname: Police
authors.forename: Veronica
authors.initials: V
authors.lastname: Muskheli
authors.forename: Charles E
authors.initials: CE
authors.lastname: Murry
mesh_terms: D000818:Animals; D006348:Cardiac Surgical Procedures; D002454:Cell Differentiation; D002455:Cell Division; D006358:Hot Temperature; D006801:Humans; D008297:Male; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000502:physiology; D018919:Neovascularization, Physiologic; D051381:Rats; D011923:Rats, Nude; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology; D013997:Time Factors; D014183:Transplantation, Heterologous