Andrea Siracusano

Granulocyte colony-stimulating factor for the treatment of cardiovascular diseases: An update with a critical appraisal

Graphical abstract Figure. No Caption available. ABSTRACT Heart failure and acute myocardial infarction are conditions that are associated with high morbidity and mortality. Significant dysfunction of the heart muscle can occur as the consequence of end‐stage chronic cardiovascular diseases or acute ischemic events that are marked by large infarction area and significant tissue necrosis. Despite the remarkable improvement of conventional treatments, a substantial proportion of patients still develops severe heart failure that can only be resolved by heart transplantation or mechanical device implantation. Therefore, novel approaches based on stem‐cell therapy can directly modify the disease process and alter its prognosis. The ability of the stem‐cells to modify and repair the injured myocardium is a challenging but intriguing concept that can potentially replace expensive and invasive methods of treatment that are associated with increased risks and significant financial costs. In that sense, granulocyte colony‐stimulating factor (G‐CSF) seems as an attractive treatment approach. Based on the series of pre‐clinical experiments and a limited amount of clinical data, it was demonstrated that G‐CSF agents possess the ability to mobilize stem‐cells from bone marrow and induce their differentiation into cardiomyocytes or endothelial cells when brought into contact with injured regions of the myocardium. However, clinical benefits of G‐CSF use in damaged myocardium remain unclear and are the topic of expert discussion. The main goal of this review is to present relevant and up‐to‐date evidence on G‐CSF therapy use in pre‐clinical models and in humans and to provide a rationale for its potential clinical applications in the future.

Human cardiac progenitor cells with regenerative potential can be isolated and characterized from 3D-electro-anatomic guided endomyocardial biopsies

AIMS In the present study, we aimed to develop a percutaneous approach and a reproducible methodology for the isolation and expansion of Cardiac Progenitor Cells (CPCs) from EndoMyocardial Biopsies (EMB) in vivo. Moreover, in an animal model of non-ischemic heart failure (HF), we would like to test whether CPCs obtained by this methodology may engraft the myocardium and differentiate. METHODS AND RESULTS EMB were obtained using a preformed sheath and a disposable bioptome, advanced via right femoral vein in 12 healthy mini pigs, to the right ventricle. EMB were enzymatically dissociated, cells were expanded and sorted for c-kit. We used 3D-Electro-Anatomic Mapping (3D-EAM) to obtain CPCs from 32 patients affected by non-ischemic cardiomyopathy. The in vivo regenerative potential of CPCs was tested in a rodent model of drug-induced non-ischemic cardiomyopathy. c-kit positive CPCs replicative capacity was assessed in 30 patients. Telomere length averaged 7.4±0.4kbp and telomerase activity was present in all preparations (1.7×105 copies). The in situ hybridization experiments showed that injected human CPCs may acquire a neonatal myocyte phenotype given the expression of the alpha-sarcomeric actin together with the presence of the Alu probe, suggesting a beneficial impact on LV performance. CONCLUSIONS The success in obtaining CPCs characterized by high regenerative potential, in vitro and in vivo, from EMB indicates that harvesting without thoracotomy in patients affected by either ischemic or non-ischemic cardiomyopathy is feasible. These initial results may potentially expand the future application of CPCs to all patients affected by HF not undergoing surgical procedures.

Molecular mechanisms of cardioprotective effects mediated by transplanted cardiac ckit+ cells through the activation of an inflammatory hypoxia-dependent reparative response

The regenerative effects of cardiac ckit+ stem cells (ckit+CSCs) in acute myocardial infarction (MI) have been studied extensively, but how these cells exert a protective effect on cardiomyocytes is not well known. Growing evidences suggest that in adult stem cells injury triggers inflammatory signaling pathways which control tissue repair and regeneration. Aim of the present study was to determine the mechanisms underlying the cardioprotective effects of ckit+CSCs following transplantation in a murine model of MI. Following isolation and in vitro expansion, cardiac ckit+CSCs were subjected to normoxic and hypoxic conditions and assessed at different time points. These cells adapted to hypoxia as showed by the activation of HIF-1α and the expression of a number of genes, such as VEGF, GLUT1, EPO, HKII and, importantly, of alarmin receptors, such as RAGE, P2X7R, TLR2 and TLR4. Activation of these receptors determined an NFkB-dependent inflammatory and reparative gene response (IRR). Importantly, hypoxic ckit+CSCs increased the secretion of the survival growth factors IGF-1 and HGF. To verify whether activation of the IRR in a hypoxic microenvironment could exert a beneficial effect in vivo, autologous ckit+CSCs were transplanted into mouse heart following MI. Interestingly, transplantation of ckit+CSCs lowered apoptotic rates and induced autophagy in the peri-infarct area; further, it reduced hypertrophy and fibrosis and, most importantly, improved cardiac function. ckit+CSCs are able to adapt to a hypoxic environment and activate an inflammatory and reparative response that could account, at least in part, for a protective effect on stressed cardiomyocytes following transplantation in the infarcted heart.

Perilipin 2 levels are increased in patients with in-stent neoatherosclerosis: A clue to mechanisms of accelerated plaque formation after drug-eluting stent implantation

BACKGROUND Perilipin 2 (PLIN2) is a protein that potentially facilitates atherogenesis in native coronary arteries or arteries with an implanted drug-eluting stent (DES). The aim of the study was to determine PLIN2 protein levels in peripheral monocytes of enrolled subjects and compare them between patients with native coronary artery disease (CAD) and those with an in-stent restenosis (ISR) due to neoatherosclerosis occurring >1 year after DES implantation. METHODS Forty-two patients were prospectively enrolled in the study in 3:1 fashion and underwent coronary catheterization. Both groups were angiographically matched for CAD burden with respect to the number of diseased vessels. Neoatherosclerosis was determined by intracoronary optical coherence tomography (OCT) among patients with ISR. RESULTS Patients with ISR due to neoatherosclerosis had significantly higher PLIN2 protein levels in peripheral blood monocytes compared to patients with native CAD (342.47 ± 75.63[SE] versus 119.51 ± 20.95, p < 0.001). PLIN2 protein levels did not significantly differ between unstable and stable disease phenotype (125.59 ± 131.02 vs. 146.14 ± 111.87, p = 0.109). CONCLUSIONS In this explorative study, PLIN2 protein levels are significantly increased in patients with neoatherosclerosis, irrespective of clinical presentation, implicating that it might play a pathogenetic role in accelerated atherosclerosis after DES implantation. Further larger clinical studies are warranted to confirm these initial findings.

DMD myogenic cells from urine-derived stem cells recapitulate the dystrophin genotype and phenotype

A ready source of autologous myogenic cells is of vital importance for drug screening and functional genetic studies in Duchenne muscular dystrophy (DMD), a rare disease caused by a variety of dystrophin gene mutations. As stem cells (SCs) can be easily and noninvasively obtained from urine specimens, we set out to determine whether they could be myogenically induced and useful in DMD research. To this end, we isolated stem cells from the urine of two healthy donors and from one patient with DMD, and performed surface marker characterization, myogenic differentiation (MyoD), and then transfection with antisense oligoribonucleotides to test for exon skipping and protein restoration. We demonstrated that native urine-derived stem cells express the full-length dystrophin transcript, and that the dystrophin mutation was retained in the cells of the patient with DMD, although the dystrophin protein was detected solely in control cells after myogenic transformation according to the phenotype. Notably, we also showed that treatment with antisense oligoribonucleotide against dystrophin exon 44 induced skipping in both native and MyoD-transformed urine-derived stem cells in DMD, with a therapeutic transcript-reframing effect, as well as visible protein restoration in the latter. Hence MyoD-transformed cells may be a good myogenic model for studying dystrophin gene expression, and native urine stem cells could be used to study the dystrophin transcript, and both diagnostic procedures and splicing modulation therapies in both patients and control subjects, without invasive and costly collection methods. New, bankable bioproducts from urine stem cells, useful for prescreening studies and therapeutic applications alike, are also foreseeable after further, more in-depth characterization.

Response to Letter Regarding Article, “Growth Properties of Cardiac Stem Cells Are a Novel Biomarker of Patients’ Outcome After Coronary Bypass Surgery”

We appreciate the interest of Drs Li and Shen in our study,1 which emphasizes the critical role that the insulin-like growth factor-1 (IGF-1) and IGF-1 receptor system has in defining the growth properties of human cardiac stem cells (hCSCs). We shared their view that IGF-1 positively interferes with the consequences of diabetes mellitus and dyslipidemia, and possibly with other cardiovascular pathologies. Based on our interest in IGF-1, a transgenic mouse model with cardiomyocyte-restricted overexpression of IGF-1 was developed.2 With this strategy, an increase in the number of ventricular myocytes was obtained, resulting in a significantly lower systolic and diastolic stress at the cellular level, together with an enhanced ability of the myocardium to sustain increases in pressure or volume loads. Overexpression of IGF-1 prevents the manifestation of the diabetic myopathy and is associated with a …