C-kit–Positive Cardiac Progenitor Cells

Abstract

One decade ago, the discovery of resident stem cells in the adult rat heart1 abolished the paradigmatic view of the heart as a terminally differentiated postmitotic organ, incapable of self-renewing, and opened a new era on resident cardiac stem cell therapeutic role to induce heart regeneration. Other studies had shown that bone marrow (BM)–derived cells injected into the injured heart could improve its function, at least in animal models,2 but the cardiac stem cell was expected to be more likely to differentiate into cardiomyocytes than cells derived from organs other than the heart, such as the BM or the adipose tissue. In keeping, a recent study confirmed a higher regenerative potential of cardiac progenitor cells (CPCs) compared with BM-derived stem cells in a mouse model of myocardial infarction.3 Article, see p 1253 Since the initial discovery of the c-kit+ cardiac stem cell, other cardiac stem cell and CPC populations have been identified. In rodents, different CPCs have been isolated on the basis of the expression of stem cell antigen 1 (Sca1)4,5 and their ability to actively extrude dyes and toxic compounds through the ATP-binding cassette surface transporter,6 identifying in this way a cardiac resident side population (SP). Islet 1–positive cardiac stem cells have been found in postnatal heart7; however, it is unclear whether these cells are present in the adult heart.8 In addition to these cell populations, cardiac-derived spheroidal aggregates named cardiospheres9 have been obtained from the heart of different species. Cardiospheres and cardiosphere-derived cells …