RESUMEN
BACKGROUND: Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) show tremendous promise for cardiac regeneration, but the successful development of hESC-CM-based therapies requires improved tools to investigate their electrical behavior in recipient hearts. While optical voltage mapping is a powerful technique for studying myocardial electrical activity ex vivo, we have previously shown that intra-cardiac hESC-CM grafts are not labeled by conventional voltage-sensitive fluorescent dyes. We hypothesized that the water-soluble voltage-sensitive dye di-2-ANEPEQ would label engrafted hESC-CMs and thereby facilitate characterization of graft electrical function and integration. METHODS: We developed and validated a novel optical voltage mapping strategy based on the simultaneous imaging of the calcium-sensitive fluorescent protein GCaMP3, a graft-autonomous reporter of graft activation, and optical action potentials (oAPs) derived from di-2-ANEPEQ, which labels both graft and host myocardium. Cardiomyocytes from three different GCaMP3+ hESC lines (H7, RUES2, or ESI-17) were transplanted into guinea pig models of subacute and chronic infarction, followed by optical mapping at 2 weeks post-transplantation. RESULTS: Use of a water-soluble voltage-sensitive dye revealed pro-arrhythmic properties of GCaMP3+ hESC-CM grafts from all three lines including slow conduction velocity, incomplete host-graft coupling, and spatially heterogeneous patterns of activation that varied beat-to-beat. GCaMP3+ hESC-CMs from the RUES2 and ESI-17 lines both showed prolonged oAP durations both in vitro and in vivo. Although hESC-CMs partially remuscularize the injured hearts, histological evaluation revealed immature graft structure and impaired gap junction expression at this early timepoint. CONCLUSION: Simultaneous imaging of GCaMP3 and di-2-ANEPEQ allowed us to acquire the first unambiguously graft-derived oAPs from hESC-CM-engrafted hearts and yielded critical insights into their arrhythmogenic potential and line-to-line variation.
Asunto(s)
Células Madre Embrionarias Humanas , Miocitos Cardíacos , Animales , Diferenciación Celular , Células Madre Embrionarias , Cobayas , MiocardioRESUMEN
Purpose To evaluate the effect and clinical importance of sunitinib on pancreatic volume in patients with gastrointestinal stromal tumor (GIST). Materials and Methods This retrospective study was approved by the institutional review board and compliant with HIPAA. The requirement to obtain informed consent was waived. The authors evaluated 65 patients with GIST treated with oral sunitinib and a control group of 30 patients with GIST who did not receive any therapy (mean age: 56 years [range, 29-75 years] vs 60 years [range, 27-78 years], respectively; P = .11) seen at their institution from January 2002 through December 2008. Segmented pancreatic volumes of study and control groups were measured with computed tomography by using commercial software by two independent readers who were blinded to study group and the timing of the scan at a median of 6.2 and 6.1 months, respectively. Pre- and posttreatment volumes (Wilcoxon signed rank test) and rate of volume change per month (Wilcoxon rank sum test) were compared. Interobserver agreement was calculated. Associations and prognostic importance of pancreatic atrophy were studied by using multivariate linear regression and Cox proportional analysis, respectively. Results Both readers recorded significant pancreatic volume loss in the study group (respective median pre- and posttreatment volume: 76.1 cm(3) and 58.4 cm(3) for reader 1 and 67.7 cm(3) and 59.0 cm(3) for reader 2; P < .0001 for both) but not in the control group (respective median pre- and posttreatment volume: 79.9 cm(3) and 83.8 cm(3) for reader 1 [P = .43] and 79.9 cm(3) and 84.8 cm(3) for reader 2 [P = .50]). The rate of volume loss per month was greater in the study group than in the control group (reader 1: -2.1% vs -0.1%, respectively, P = .003; reader 2: -2.0% vs -0.3%, P < .0001). Twenty-three of the 65 patients who received sunitinib (35%) showed at least 3% pancreatic volume loss per month, compared with only one of the 30 patients in the control group (3%). The concordance correlation coefficient for pre- and posttreatment measurements was 0.83 (95% confidence interval [CI]: 0.75, 0.89) and 0.91 (95% CI: 0.86, 0.94), respectively, and the mean relative difference was 0.04% and 1.2%. Sunitinib treatment was independently associated with pancreatic atrophy (P = .03; risk estimate: 2.64; 95% CI: 0.17, 5.11). At Cox proportional analysis within the study group, more than 3%, more than 5%, and more than 7% loss per month were independently associated with worse survival (P < .001, hazard ratio: >1.00 for all). Conclusion Pancreatic atrophy is a sunitinib-associated toxicity detected at imaging. It may be a clinically important biomarker because a higher rate of pancreatic atrophy was independently associated with shorter survival. (©) RSNA, 2016.