Overexpression of integrin-linked kinase induces cardiac stem cell expansion.
OBJECTIVE
Recent evidence suggests that the adult heart contains stem cells that are capable of self-renewal as well as multilineage differentiation. However, their inherent capacity for self-renewal is limiting to cell replacement applications. Integrin-linked kinase is a multifunctional protein kinase that activates Wnt target genes implicated in the symmetric replication of embryonic stem cells.


METHODS
Primary cultures derived from human fetal cardiac tissue (19-22 weeks' gestation) were grown in serum-free media and evaluated for the presence of cardiac progenitor cells. The effect of integrin-linked kinase was ascertained by adenoviral overexpression.


RESULTS
Cultures infected with wild-type integrin-linked kinase yielded a significant (P = .001), approximately 5-fold increase in both the absolute number and the frequency of c-Kit-positive, myosin-negative cells. Cardiospheres, comprised on morphologically homogeneous, anchorage-independent cells, were reproducibly present at days 7 to 10 and formed derivative cardiospheres in multiple passages. Integrin-linked kinase infection of primary cardiac cell cultures resulted in a greater number of primary spheres at each cell density tested, compared with untreated and virus controls (P = .001). Secondary spheres transferred to differentiation medium and 5-aza-deoxycytodine (10 micromol/L) generated cells exhibiting biochemical evidence of differentiation into cardiomyocytes, smooth muscle cells, and endothelial cells.


CONCLUSIONS
This study demonstrates that self-renewing cardiospheres generated from human fetal cardiac cells are composed of cells exhibiting the properties of stem cells, including the capacity for self-renewal and multilineage differentiation. Our results suggest that integrin-linked kinase promotes stem cell amplification and can be applied therapeutically to overcome a major limitation in the field of cardiac regenerative medicine.
Yamabi
Hideaki
H
Cardiovascular Research, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.
Lu
Huanzhang
H
Dai
Xiaojing
X
Lu
Yanruo
Y
Hannigan
Gregory
G
Coles
John G
JG
D049109:Cell Proliferation; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006801:Humans; D009206:Myocardium / Q000166:cytology*; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology*; D013234:Stem Cells / Q000502:physiology*; D000099200:Scaffold Protein ILK
D017346:Protein Serine-Threonine Kinases; D000099200:Scaffold Protein ILK