Stimulation of paracrine pathways with growth factors enhances embryonic stem cell engraftment and host-specific differentiation in the heart after ischemic myocardial injury.
BACKGROUND
Growth factors play an essential role in organogenesis. We examine the potential of growth factors to enhance cell engraftment and differentiation and to promote functional improvement after transfer of undifferentiated embryonic stem cells into the injured heart.


RESULTS
Green fluorescent protein (GFP)-positive embryonic stem cells derived from 129sv mice were injected into the ischemic area after left anterior descending artery ligation in allogenic (BALB/c) mice. Fifty nanograms of recombinant mouse vascular endothelial growth factor, fibroblast growth factor (FGF), and transforming growth factor (TGF) was added to the cell suspension. Separate control groups were formed in which only the growth factors were given. Echocardiography was performed 2 weeks later to evaluate heart function (fractional shortening [FS]), end-diastolic diameter, and left ventricular wall thickness). Hearts were harvested for histology (connexin 43, alpha-sarcomeric actin, CD3, CD11c, major histocompatability complex class I, hematoxylin-eosin). Degree of restoration (GFP-positive graft/infarct area ratio), expression of cardiac markers, host response, and tumorigenicity were evaluated. Cell transfer resulted in improved cardiac function. TGF-beta led to better restorative effect and a stronger expression of connexin 43, alpha-sarcomeric actin, and major histocompatability complex class I. TGF-beta and FGF retained left ventricular diameter. FS was better in the TGF-beta, FGF, and embryonic stem cells-only group compared with left anterior descending artery-ligated controls. Growth factors with cells (TGF-beta, FGF) resulted in higher FS and smaller end-diastolic diameter than growth factors alone.


CONCLUSIONS
Growth factors can promote in vivo organ-specific differentiation of early embryonic stem cells and improve myocardial function after cell transfer into an area of ischemic lesion. TGF-beta should be considered as an adjuvant for myocardial restoration with the use of embryonic stem cells.
Kofidis
Theo
T
Department of Cardiothoracic Surgery, Falk Research Center, Stanford University Medical School, Stanford, Calif 94305, USA. tkofidis@stanford.edu
de Bruin
Jorg L
JL
Yamane
Toshiyuki
T
Tanaka
Masashi
M
Lebl
Darren R
DR
Swijnenburg
Rutger-Jan
RJ
Weissman
Irving L
IL
Robbins
Robert C
RC
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D004622:Embryo, Mammalian / Q000166:cytology; D006085:Graft Survival / Q000187:drug effects*; D049452:Green Fluorescent Proteins; D006133:Growth Substances / Q000494:pharmacology*; D051379:Mice; D008815:Mice, Inbred Strains; D017202:Myocardial Ischemia / Q000473:pathology / Q000628:therapy; D015428:Myocardial Reperfusion Injury / Q000473:pathology / Q000628:therapy*; D009206:Myocardium / Q000166:cytology; D019899:Paracrine Communication / Q000187:drug effects*; D033581:Stem Cell Transplantation; D016212:Transforming Growth Factor beta / Q000627:therapeutic use
D006133:Growth Substances; D016212:Transforming Growth Factor beta; D049452:Green Fluorescent Proteins