Multipotent adult resident cardiac stem cells (CSCs) were first identified by the expression of c-kit, the stem cell factor receptor. However, in the adult myocardium c-kit alone cannot distinguish CSCs from other c-kit-expressing (c-kitpos) cells. The adult heart indeed contains a heterogeneous mixture of c-kitpos cells, mainly composed of mast and endothelial/progenitor cells. This heterogeneity of cardiac c-kitpos cells has generated confusion and controversy about the existence and role of CSCs in the adult heart. Here, to unravel CSC identity within the heterogeneous c-kit-expressing cardiac cell population, c-kitpos cardiac cells were separated through CD45-positive or -negative sorting followed by c-kitpos sorting. The blood/endothelial lineage-committed (Lineagepos) CD45posc-kitpos cardiac cells were compared to CD45neg(Lineageneg/Linneg) c-kitpos cardiac cells for stemness and myogenic properties in vitro and in vivo. The majority (~90%) of the resident c-kitpos cardiac cells are blood/endothelial lineage-committed CD45posCD31posc-kitpos cells. In contrast, the LinnegCD45negc-kitpos cardiac cell cohort, which represents ⩽10% of the total c-kitpos cells, contain all the cardiac cells with the properties of adult multipotent CSCs. These characteristics are absent from the c-kitneg and the blood/endothelial lineage-committed c-kitpos cardiac cells. Single Linnegc-kitpos cell-derived clones, which represent only 1–2% of total c-kitpos myocardial cells, when stimulated with TGF-β/Wnt molecules, acquire full transcriptome and protein expression, sarcomere organisation, spontaneous contraction and electrophysiological properties of differentiated cardiomyocytes (CMs). Genetically tagged cloned progeny of one Linnegc-kitpos cell when injected into the infarcted myocardium, results in significant regeneration of new CMs, arterioles and capillaries, derived from the injected cells. The CSC’s myogenic regenerative capacity is dependent on commitment to the CM lineage through activation of the SMAD2 pathway. Such regeneration was not apparent when blood/endothelial lineage-committed c-kitpos cardiac cells were injected. Thus, among the cardiac c-kitpos cell cohort only a very small fraction has the phenotype and the differentiation/regenerative potential characteristics of true multipotent CSCs.

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1 The nuclear factor-kB (NF-kB) is a transcription factor which plays a pivotal role in the induction of genes involved in physiological processes as well as in the response to injury and in¯ammation. Dithiocarbamates are antioxidants which are potent inhibitors of NF-kB. 2 We postulated that pyrrolidine dithiocarbamate (PDTC) would attenuate in¯ammation. In the present study we investigate the e ects of PDTC in animal models of acute and chronic in¯ammation (carrageenan-induced pleurisy and collagen-induced arthritis). 3 We report here for the ®rst time that PDTC (given at 100, 30 or 10 mg kg 71 i.p. in the pleurisy model or at 10 mg kg 71 i.p. every 48 h in the arthritis model) exerts potent anti-in¯ammatory e ects (e.g. signi®cant reduction of (A) pleural exudate formation, (B) polymorphonuclear cell in®ltration, (C) lipid peroxidation, (D) inducible nitric oxide synthase (iNOS) activity and nitric oxide production (E) plasma and pleural exudates levels of interleukin-1b and tumour necrosis factor-a, (F) histological injury and (G) delayed development of clinical indicators). 4 Furthermore, PDTC reduced immunohistochemical evidence of (A) formation of nitrotyrosine, (B) activation of poly (ADP-ribose) polymerase (PARP), (C) expression of iNOS and (D) expression of cyclo-oxygenase-2 (COX-2) in the lungs of carrageenan-treated mice and in the joints from collagen-treated mice. 5 Additionally, Western blotting and immunohistochemical analysis of lung tissue revealed that PDTC prevented degradation of IKB-a and translocation of NF-kB from the cytoplasm into the nucleus. 6 Taken together, our results clearly demonstrate that prevention of the activation of NF-kB by PDTC reduces the development of acute and chronic in¯ammation. Therefore, inhibition of NF-kB may represent a novel approach for the therapy of in¯ammation.

These results suggest that (1). an enhanced formation of NO by iNOS contributes to the pathophysiology of renal I/R injury and (2). GW274150 reduces I/R injury of the kidney. We propose that selective inhibitors of iNOS activity may be useful against renal dysfunction and injury associated with I/R of the kidney.

The protection afforded by the pretreatment regime of EPO was greater than that of administering EPO as a single bolus upon reperfusion. We propose that different mechanisms underlie the protective effects seen with EPO when given as either a daily pretreatment or as a single bolus, which need to be further investigated.