, Volume 13, Issue 4, pp 633-645
Date: 21 Aug 2010

Tracking Long-Term Survival of Intramyocardially Delivered Human Adipose Tissue-Derived Stem Cells Using Bioluminescence Imaging

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Abstract

Purpose

Transplantation of a regenerative cell population derived from human subcutaneous adipose tissue (hASCs) for cardiac regeneration represents a promising therapy due to the capacity of these cells for proliferation and differentiation. Understanding the fate of injected hASCs would help to understand how hASCs work in vivo. The aim of this study was to track the long-term fate, including survival, differentiation, proliferation, apoptosis, migration, and growth factor secretion of intramyocardially injected hASCs following experimental acute myocardial infarction in an immunodeficient mouse model.

Methods

Myocardial infarction was experimentally induced in severe combined immunodeficient mice by permanent ligation of the left anterior descending coronary artery. Lentivirally labeled hASCs (5 × 105; expressing green fluorescence protein [GFP] and luciferase) were injected into the peri-infarct region. Colony formation, growth kinetics, and differentiation of transduced hASCs were analyzed in vitro and compared to those of untransduced hASCs. The survival and migration of injected hASCs were tracked by luciferase-based bioluminescence imaging for 10 weeks. Immunofluorescence and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were used to assess differentiation, proliferation, growth factor expression, or apoptosis of grafted hASCs in infarcted hearts and potential distribution to other tissues.

Results

Lentivirus transduction and GFP and luciferase expression did not influence proliferation or differentiation of hASCs. Bioluminescence imaging demonstrated that injected hASCs survived in infarcted hearts during the follow-up of 10 weeks. Immunofluorescence confirmed that hASCs engrafted in ischemic hearts expressed bFGF and IGF-1, and did not migrate into other organs. Of all engrafted hASCs, 3.5% differentiated into cardiomyocytes or endothelial cells. Other cells maintained their proliferative potential or underwent apoptosis.

Conclusion

Luciferase-based bioluminescence imaging allows long-term tracking of intramyocardially injected hASCs in living mice. The hASCs might enhance function of injured hearts through long-term engraftment, growth factor secretion, and transdifferentiation to cardiomyocytes and endothelial cells.

Significance:

Transplantation of a regenerative cell populations derived from human subcutaneous adipose tissue (hASCs) for cardiac regeneration represents a promising therapy due to the capacity of these cells for proliferation and differentiation. In this study, we systematically assessed the persistence, differentiation, and paracrine fate of intramyocardially injected hASCs for 10 weeks after myocardial infarction. Our results show that (1) injected hASCs survive long-term in infarcted heart, (2) injected hASCs not only secrete growth factors (basic fibroblast growth factor and insulin-like growth factor-1) but also differentiated into cardiomyocytes and endothelial cells, and (3) bioluminescent imaging of genetically labeled hASCs was an effective tool for serial quantitation of cell engraftment and distribution. Understanding the fate of injected hASCs should help to understand how hASCs work in vivo and optimize hASC-based therapeutic strategy for myocardial regeneration.