Abstract
Background aims
Starting from experimental data proposing hematopoietic stem cells as candidates for cardiac repair, we postulated that human peripheral blood (PB) CD34+ cells mobilized by hematopoietic growth-factor (G-CSF) would contain cell subpopulations capable of regenerating post-ischemic myocardial damages.
Methods
In a phase I clinical assay enrolling seven patients with acute myocardial infarct, we directly delivered to the injured myocardium autologous PB CD34+ cells previously mobilized by G-CSF, collected by leukapheresis and purified by immunoselection. In parallel, we looked for the eventual presence of cardiomyocytic and endothelial progenitor cells in leukapheresis products of these patients and controls, using flow cytometry, reverse transcription-quantitative (RTQ)–polymerase chain reaction (PCR), cell cultures and immunofluorescence analyzes.
Results
The whole clinical process was feasible and safe. All patients were alive at an average follow-up of 49 months (range 24–76 months). Improvement of heart function parameters became obvious from the third month following cell reinjection. Left ventricular ejection fraction values progressively and dramatically increased with time, associated with PetScan demonstration of myocardial structure regeneration and revascularization and New York Heart Association (NYHA) grade improvement. Furthermore, we identified PB CD34+ cell subpopulations expressing characteristics of both immature and mature endothelial and cardiomyocyte progenitor cells. In vitro CD34+ cell cultures on a specific medium induced development of adherent cells featuring morphologies, gene expression and immunocytochemistry characteristics of endothelial and cardiac muscle cells.
Conclusions
Mobilized CD34+ cells contain stem cells committed along endothelial and cardiac differentiation pathways, which could play a key role in a proposed two-phase mechanism of myocardial regeneration after direct intracardiac delivery, probably being responsible for the long-term clinical benefit observed.
Acknowledgments
We thank A. Eidenschenk, M. Scrofani and C. Tancredi from IRHT (research study) and H. Lewandowski, P. Peter, V. Reymond and G. Stampfler from the Department of Hematology of Mulhouse Hospital (cell processing) for their expert technical experience, L. Lacôte and C. Sparks for the preparation of the manuscript, and Pr N. Theze (University Bordeaux 2) for helpful comments.
Sources of funding
This work was supported for its clinical part by (1) a grant from the French Ministry of Health (PHRC number 2911) and (2) Chugaï France, which gave Granocyte® freely and, for its biologic research part, by (3) a grant from the ‘Conseil Général du Haut-Rhin’.
Disclosure
All authors declare that they have no conflicts of interest.