Combined meta-analysis of preclinical cell therapy studies shows overlapping effect modifiers for multiple diseases

Introduction

Cell therapy has been studied in many different research domains. Cellular replacement of damaged solid tissues is at an early stage of development, with much still to be understood. Systematic reviews and meta-analyses are widely used to aggregate data and find important patterns of results within research domains.

We set out to find common biological denominators affecting efficacy in preclinical cell therapy studies for renal, neurological and cardiac disease.

Methods

We used datasets of five previously published meta-analyses investigating cell therapy in preclinical models of chronic kidney disease, spinal cord injury, stroke and ischaemic heart disease. We transformed primary outcomes to ratios of means to permit direct comparison across disease areas. Prespecified variables of interest were species, immunosuppression, cell type, cell origin, dose, delivery and timing of the cell therapy.

Results

The five datasets from 506 publications yielded data from 13 638 animals. Animal size affects therapeutic efficacy in an inverse manner. Cell type influenced efficacy in multiple datasets differently, with no clear trend for specific cell types being superior. Immunosuppression showed a negative effect in spinal cord injury and a positive effect in cardiac ischaemic models. There was a dose–dependent relationship across the different models. Pretreatment seems to be superior compared with administration after the onset of disease.

Conclusions

Preclinical cell therapy studies are affected by multiple variables, including species, immunosuppression, dose and treatment timing. These data are important when designing preclinical studies before commencing clinical trials.

Abstract 345: Tissue-Printed Cardiac Progenitor Cells Improve Myocardial Function in a Mouse Model of MI

Introduction: Tissue engineering is emerging as a therapeutic approach to overcome the limitations of cell therapy and mechanically support the ventricular wall. Tissue printing technology (TP) allows for the construction of a defined and organized tissue engineered construct. Hypothesis: The aim of our study was to evaluate the combination of TP and cardiac-derived cardiomyocyte progenitor cells (CMPCs) to build a cardiogenic construct.

Methods: Sca-1 + CMPCs were printed in gelatin/hyaluronic acid matrix (30x10 6 cells/ ml) to form a biocomplex made of 6 perpendicularly printed layers with a surface of 2cm x 2cm and a structure 500 µm thick. After in vitro characterization, the printed biocomplex was transplanted in a mouse model of MI. Cardiac function was evaluated by MRI.

Results: After printing, CMPCs retain cardiogenic gene expression for up to 4 weeks, as evaluated by PCR (n=4). Immunofluorescence analysis confirmed expression of Nkx2.5 and Ki67 with a slight decrease after 7 days in culture (77% vs 52% and 79% vs 64% respectively, n=5, p<0.05). After differentiation, hCMPCs increased MLC2a and TnI gene levels (n=4). In vivo engrafted hCMPCs expressed Nkx 2.5. TnI expression was also detected after 2 weeks (n=3) and 28 days (n=5). CD31 expression was detected in low number of transplanted hCMPCs. Endogenous CD45 expression was similar at 7 and 14 days, mainly localized at the border of the matrix (n=3). At 28 days, a reduction in EDV and ESV dilation was observed, as compared to control (EDV:107,87 ± 7,41 vs 136,6 ±9,6 and ESV:89 ± 6,6 vs 118 ±12, respectively, n=8 each group, p<0.05), although no significant differences could be observed with matrix only (EDV;107,87 ± 7,41 vs 120,8 ±9,5 and ESV;89 ± 6,6 vs 97 ±10, respectively, n=7). Infarct wall thinning was reduced in both groups compare to the control (457 ± 69,8 vs 357,8 ±18,6 and 201,1± 6,3 μ m, respectively; n=5 each group, p<0.05).

Conclusion: Here, we showed that hCMPCs can be printed and cultured in Gel/ HA. Transplantation in a mouse model of MI contributed to an improvement in cardiac function and a better remodeling upon injury. Long-term follow up to address its effect on infarct size, cardiomyocytes survival and regeneration, revascularization, endogenous CPCs activation, and inflammation is ongoing.

Caveolin-1 influences vascular protease activity and is a potential stabilizing factor in human atherosclerotic disease

Caveolin-1 (Cav-1) is a regulatory protein of the arterial wall, but its role in human atherosclerosis remains unknown. We have studied the relationships between Cav-1 abundance, atherosclerotic plaque characteristics and clinical manisfestations of atherosclerotic disease.We determined Cav-1 expression by western blotting in atherosclerotic plaques harvested from 378 subjects that underwent carotid endarterectomy. Cav-1 levels were significantly lower in carotid plaques than non-atherosclerotic vascular specimens. Low Cav-1 expression was associated with features of plaque instability such as large lipid core, thrombus formation, macrophage infiltration, high IL-6, IL-8 levels and elevated MMP-9 activity. Clinically, a down-regulation of Cav-1 was observed in plaques obtained from men, patients with a history of myocardial infarction and restenotic lesions. Cav-1 levels above the median were associated with absence of new vascular events within 30 days after surgery [0% vs. 4%] and a trend towards lower incidence of new cardiovascular events during longer follow-up. Consistent with these clinical data, Cav-1 null mice revealed elevated intimal hyperplasia response following arterial injury that was significantly attenuated after MMP inhibition. Recombinant peptides mimicking Cav-1 scaffolding domain (Cavtratin) reduced gelatinase activity in cultured porcine arteries and impaired MMP-9 activity and COX-2 in LPS-challenged macrophages. Administration of Cavtratin strongly impaired flow-induced expansive remodeling in mice.This is the first study that identifies Cav-1 as a novel potential stabilizing factor in human atherosclerosis. Our findings support the hypothesis that local down-regulation of Cav-1 in atherosclerotic lesions contributes to plaque formation and/or instability accelerating the occurrence of adverse clinical outcomes. Therefore, given the large number of patients studied, we believe that Cav-1 may be considered as a novel target in the prevention of human atherosclerotic disease and the loss of Cav-1 may be a novel biomarker of vulnerable plaque with prognostic value.