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Although the first non-imaging nuclear probe for clinical application was already available 25 years ago, this technique is still underused for the assessment of ventricular function. Over the years substantial technological progress rendered nuclear probes more accurate and easier to use, and so far the applicability of these devices has been evaluated in several experimental and clinical contexts. Bedside devices can be used in the evaluation of hemodynamically unstable patients and of drug therapy. In patients with several heart diseases, particularly with ischemic cardiomyopathy, accurate information on the changes in ventricular function occurring during routine activities, as well as during structured activities, can be provided using the ambulatory probes. This review will focus on the development and clinical application of these diagnostic tools.

Tirofiban is a fibrinogen receptor antagonist, generated using the tripeptide Arg-Gly-Asp (RGD) as a template. RGD activates integrin receptors and integrin-mediated signals are necessary for normal cells to promote survival and stimulate cell cycle progression. We investigated whether tirofiban activated growth-stimulatory signals in endothelium. For this study human umbilical vein endothelial cells (HUVEC) and human aortic endothelial cells (HAEC) were used. Analysis of cell proliferation, by cell counts, showed that the number of endothelial cells doubled after 72 h of culture in the absence of tirofiban, while they were tripled and even quadrupled, in the presence of increasing doses of the drug. Moreover, tirofiban-stimulated cells had a greater ability to migrate through the transwell filters of Boyden chamber, compared to unstimulated cells. The scratch assay, which mimics cell migration during wound healing, showed that tirofiban stimulated HUVECs to migrate into the leading hedge of the scratch. Western blot showed that tirofiban increased the expression levels of VEGF and the downstream effectors Erk and cyclin D. An inhibitor of VEGFR2 counteracted tirofiban-induced-proliferation, suggesting a role for VEGF in such effect. Our study shows that tirofiban stimulates the migration and proliferation of endothelial cells suggesting that it can promote endothelial repair. Ex vivo cultures of arterial rings confirmed the growth stimulatory effect of tirofiban on endothelium. Thus, the benefits of tirofiban in those with acute coronary syndromes undergoing PTCA may be due to rapid endothelization of damaged vessel, besides antiplatelet effects.

Although considered promising for use in drug-eluting stents (DES), tacrolimus failed clinically. Tacrolimus inhibits growth factor production but can also act as a growth factor on vascular smooth muscle cells (VSMC). This unexpected proliferative stimulus could reverse the beneficial effects of the drug on restenosis. We hypothesized that tacrolimus' association with statins, which lower cholesterol and impair cell proliferation, could restore tacrolimus' beneficial effect by abrogating the aberrant proliferative stimulus. Additionally, since maintenance of endothelial function represents a challenge for new-generation DES, we investigated the combined effect of tacrolimus and atorvastatin on endothelial cells. Human VSMC and umbilical vein endothelial cells (HUVEC) were incubated with 100 nM tacrolimus and increasing doses of atorvastatin (0–3.0 μM). Atorvastatin plus tacrolimus dose-dependently inhibited VSMC proliferation. The percentage of cells incorporating 5-bromo-2′-deoxyuridine (BrdU) in their DNA was 49 ± 14% under basal conditions, 62 ± 15% ( P = 0.01) with tacrolimus, 40 ± 22% with 3 μM atorvastatin, and 30 ± 7% ( P < 0.05) with 3 μM atorvastatin plus tacrolimus. Atorvastatin downregulated β-catenin, Erk1 and Erk2, and cyclin B in tacrolimus-stimulated VSMC. In contrast, atorvastatin plus tacrolimus did not affect proliferation of endothelial cells. The percentage of HUVEC incorporating BrdU in their DNA was 47 ± 8% under basal conditions, 58 ± 6% ( P = 0.01) with tacrolimus, 45 ± 4% with 3 μM atorvastatin, and 49 ± 1% with 3 μM atorvastatin plus tacrolimus. Both agents stimulated endoglin production by HUVEC. Taken together, these results suggest that, when combined with tacrolimus, atorvastatin exerts a dose-dependent antiproliferative effect on VSMC. In contrast, atorvastatin acts in concert with tacrolimus in HUVEC to stimulate production of endoglin, a factor that has an important role in endothelial repair. Our study supports the conclusion that prevention of postcoronary in-stent restenosis and late thrombosis may benefit of concomitant association of tacrolimus and high doses of atorvastatin.

CXCR4 is a chemokine receptor implicated in the metastatic process. The CXCR4 ligand, CXCL12, was shown to bind also the CXCR7 receptor, a recently deorphanized chemokine receptor whose signalling pathway and function are still controversial. This study was conducted to determine patients clinic-pathological factors and outcome according to the expressions of CXCR4 and CXCR7 in renal cell carcinoma (RCC). CXCR4 and CXCR7 expression was evaluated in 223 RCC patients through immunohistochemistry; moreover CXCR4 and CXCR7 was detected in 49 others consecutive RCC patients trough RT- PCR. CXCR4 expression was low in 42/223 RCC (18.8%), intermediate in 71/223 (31.9%) and high in 110/223 (49.3%). CXCR7 expression was low in 44/223 RCC patients (19.8%), intermediate in 65/223 (29.1%) and high in 114/223 (51.1%). High CXCR4 and high CXCR7 expression predicted shorter disease free survival. In multivariate analysis, high CXCR4 expression (p= 0.0061), high CXCR7 (p= 0.0194) expression and the concomitant high expression of CXCR4 and CXCR7 (p= 0.0235) are independent prognosis factors. Through RT-PCR, CXCR4 was overexpressed in 36/49 and CXCR7 in 33/49 samples correlating with symptoms at diagnosis and lymph nodes status. So we can hypothesize that CXCR4 and CXCR7, singularly evaluated and in combination, are valuable prognostic factors in RCC patients.

The chemokine receptor CXCR4 and CD133, putative stem cell markers, were previously described in renal cancer (RCC). To evaluate the biological and prognostic role of CD133 and CXCR4 in RCC the expression was evaluated through qPCR and immunoblotting in human renal cancer cell lines (786-O, A498, ACHN, CAKI-1, SN12C, TK10, UO31) and patients biopsies. Renal cancer cells and surgical biopsies expressed functional CXCR4 while CD133 was not detectable. CXCR4 and CD133 expression was then evaluated in 240 renal cancer patients through immunohistochemistry. CXCR4 and CD133 were low in 19.1% and 59.6%; intermediate in 20% and 17.9%; high in 60.8% and 22.5% of the cases, respectively. CXCR4 was overexpressed in tumours (p= 0.02), while CD133 was over expressed in healthy tissues (p= 0.04). Disease free survival Kaplan Meier plots suggest that prognosis is unfavourable for patients whose primary tumours express CXCR4 (p= 0.0199) but nor CD133 (p= 0.151) neither the concomitant CXCR4-CD133 (p=0.848) high expression affected prognosis. Analysis of prognostic factors suggests that age, clinical presentation, AJCC stage and CXCR4 had a significant prognostic value at the univariate analysis. The CXCR4 predictive ability was confirmed at the multivariate analysis while no prognostic role was identified for CD133.Thus concomitant CD133 and CXCR4 evaluation is not worth in RCC patient while the CXCR4 prognostic role encourage CXCR4 antagonists as promising therapeutic option.