Stem-like cells traffic from heart ex vivo, expand in vitro, and can be transplanted in vivo.
BACKGROUND
Cells with stem cell surface markers have been identified in heart tissue. Early indications suggest that these are cardiac progenitor cells that could contribute to cardiac repair/regeneration. Clinically relevant therapeutic strategies based on these cells will require improved methods for their isolation and characterization of determinants of their mobilization, proliferation and differentiation.


METHODS
An ex vivo culture system was developed that promotes trafficking of progenitor-like cells from mouse ventricles to a culture surface. Cells that "trafficked" from cardiac tissue were phenotyped by flow cytometry and immunohistochemistry.


RESULTS
Morphologically distinct cells spontaneously trafficked from mouse ventricular tissue, adhered in culture, and proliferated for up to 4 weeks in Dulbecco's minimal essential media supplemented with fetal calf serum. After 4 weeks in culture, cell number declined. Co-culture with unfractionated bone marrow restored the proliferation of these trafficked cells. A significant population of the trafficked cells expressed a phenotype consistent with that of a myogenic progenitor such as: c-kit+, Sca-1+, CD45-, CD34-, CD90.2-, MyoD1-, desmin-, muscle-specific actin-, and, infrequently, myogenin+. An expanded population of trafficked cells from ventricles of mice expressing green fluorescent protein (GFP+) and containing cardiac-derived progenitor cells were injected into the pericardial space of GFP- mice. GFP+ cells trafficked throughout the heart but retained a primitive undifferentiated morphology. However, when injected into the pericardial space of Apo-E-deficient mice with coronary vasculopathy, progenitor-like cells trafficked into myocardium, and GFP+ cells differentiated into vessel-lining endothelial cells and, rarely, smooth muscle and cardiomyocytes.


CONCLUSIONS
Progenitor-like cells in the heart can be mobilized by tissue injury to spontaneously traffic from cardiac tissue and can expand in culture by co-culture with bone marrow. When re-infused by pericardiocentesis, these primitive cells traffic into heart, retain immature morphology, but are capable of undergoing injury-induced differentiation. The novel method described herein permits further characterization of cardiac-derived progenitor cells, which are a candidate for cardiac regeneration strategies.
Steele
A
A
Department Pathology and Laboratory Medicine, All Children's Hospital, St. Petersburg, Florida 33701, USA. steelea@allkids.org
Jones
O Y
OY
Gok
F
F
Marikar
Y
Y
Steele
P
P
Chamizo
W
W
Scott
M
M
Boucek
R J
RJ
D000818:Animals; D001854:Bone Marrow Cells; D018929:Cell Culture Techniques; D002465:Cell Movement / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D018920:Coculture Techniques; D005434:Flow Cytometry; D006352:Heart Ventricles / Q000166:cytology* / Q000378:metabolism; D007150:Immunohistochemistry; D016130:Immunophenotyping; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D020519:Pericardiocentesis; D012038:Regeneration / Q000502:physiology; D013234:Stem Cells / Q000378:metabolism