Citations

Polycystic kidney disease (PKD) has been linked to abnormal structure/function of ciliary proteins, leading to renal dysfunction. Recently, attention has been focused in the significant vascular abnormalities associated with PKD, but the mechanisms underlying this phenomenon remain elusive. Here, we seek to define the molecular events regulating the angiogenic imbalance observed in PKD. Using micro computed tomography (n=7) and protein expression analysis (n=5), we assessed the vascular density and the angiogenic profile of noncystic organs in a well-established PKD rat model (Polycystic Kidney-PCK rat). Heart and lungs of PCK rats have reduced vascular density and decreased expression of angiogenic factors compared with wild type. Similarly, PCK-vascular smooth muscle cells (VSMCs; n=4) exhibited lower levels of vascular markers. Then, using small interfering RNA (n=4), we determined the role of the ciliary protein fibrocystin in wild type-VSMCs, a critical component/regulator of vascular structure and function. Reduction of fibrocystin in wild type-VSMCs (n=4) led to an abnormal angiogenic potential similar to that observed in PCK-VSMCs. Furthermore, we investigated the involvement of the hedgehog signaling, a pathway closely linked to the primary cilium and associated with vascular development, in PKD. Mechanistically, we demonstrated that impairment of the hedgehog signaling mediates, in part, this abnormal angiogenic phenotype. Lastly, overexpression of Gli1 in PCK-VSMCs (n=4) restored the expression levels of proangiogenic molecules. Our data support a critical role of fibrocystin in the abnormal vascular phenotype of PKD and indicate that a dysregulation of hedgehog may be responsible, at least in part, for these vascular deficiencies.

Abstract Little is known on the phenotypic characteristics of stem cells (SCs) after they are transplanted to the myocardium, in part due to lack of noninvasive platforms to study SCs directly in the living subject. Reporter gene imaging has played a valuable role in the noninvasive assessment of cell fate in vivo. In this study, we validated a pathway-specific reporter gene that can be used to noninvasively image the phenotype of SCs transplanted to the myocardium. Rat mesenchymal SCs (MSCs) were studied for phenotypic evidence of myogenic characteristics under in vitro conditions. After markers of myogenic characteristics were identified, we constructed a reporter gene sensor, comprising the firefly luciferase (Fluc) reporter gene driven by the troponin T (TnT) promoter (cardio MSCs had threefold expression in polymerase chain reaction compared to control MSCs) using a two-step signal amplification strategy. MSCs transfected with TnT-Fluc were studied and validated under in vitro conditions, showing a strong signal after MSCs acquired myogenic characteristics. Lastly, we observed that cardio MSCs had higher expression of the reporter sensor compared to control cells (0.005 ± 0.0005 vs 0.0025 ± 0.0008 Tnt-Fluc/ubiquitin-Fluc, P < .05), and that this novel sensor can detect the change in the phenotype of MSCs directly in the living subject. Pathway-specific reporter gene imaging allows assessment of changes in the phenotype of MSCs after delivery to the ischemic myocardium, providing important information on the phenotype of these cells. Imaging sensors like the one described here are critical to better understanding of the changes that SCs undergo after transplantation.

Valvular interstitial cells from diseased aortic valve leaflets show their ability to regenerate–to proliferate and grow, to express appropriate genes and to deposit suitable proteins–in a non-degenerative nanofibrous substrate.

Polycystic kidney disease (PKD) is a common cause of end-stage renal failure, for which there is no accepted treatment. Progenitor and stem cells have been shown to restore renal function in a model of renovascular disease, a disease that shares many features with PKD. The objective of this study was to examine the potential of adult stem cells to restore renal structure and function in PKD. Bone marrow-derived mesenchymal stromal cells (MSCs, 2.5 × 10 5 ) were intrarenally infused in 6-week-old PCK rats. At 10 weeks of age, PCK rats had an increase in systolic blood pressure (SBP) versus controls (126.22 ± 2.74 vs. 116.45 ± 3.53 mmHg, p < 0.05) and decreased creatinine clearance (3.76 ± 0.31 vs. 6.10 ± 0.48 μl/min/g, p < 0.01), which were improved in PKD animals that received MSCs (SBP: 114.67 ± 1.34 mmHg, and creatinine clearance: 4.82 ± 0.24 μl/min/g, p = 0.001 and p = 0.003 vs. PKD, respectively). MSCs preserved vascular density and glomeruli diameter, measured using microcomputed tomography. PCK animals had increased urine osmolality (843.9 ± 54.95 vs. 605.6 ± 45.34 mOsm, p < 0.01 vs. control), which was improved after MSC infusion and not different from control (723.75 ± 56.6 mOsm, p = 0.13 vs. control). Furthermore, MSCs reduced fibrosis and preserved the expression of proangiogenic molecules, while cyst size and number were unaltered by MSCs. Delivery of exogenous MSCs improved vascular density and renal function in PCK animals, and the benefit was observed up to 4 weeks after a single infusion. Cell-based therapy constitutes a novel approach in PKD.

Abstract Objective Polycystic kidney disease ( PKD ) is a common cause of end‐stage renal failure and many of these patients suffer vascular dysfunction and hypertension. It remains unclear whether PKD is associated with abnormal microvascular structure. Thus, this study examined the renovascular structure in PKD . Methods PKD rats ( PCK model) and controls were studied at 10 weeks of age, and mean arterial pressure ( MAP ), renal blood flow, and creatinine clearance were measured. Microvascular architecture and cyst number and volume were assessed using micro‐computed tomography, and angiogenic pathways evaluated. Results Compared with controls, PKD animals had an increase in MAP (126.4 ± 4.0 vs. 126.2 ± 2.7 mmHg) and decreased clearance of creatinine (0.39 ± 0.09 vs. 0.30 ± 0.05 mL/min), associated with a decrease in microvascular density, both in the cortex (256 ± 22 vs. 136 ± 20 vessels per cm 2 ) and medullar (114 ± 14 vs. 50 ± 9 vessels/cm 2 ) and an increase in the average diameter of glomeruli (104.14 ± 2.94 vs. 125.76 ± 9.06 mm). PKD animals had increased fibrosis (2.2 ± 0.2 fold vs. control) and a decrease in the cortical expression in hypoxia inducible factor 1‐α and vascular endothelial growth factor. Conclusions PKD animals have impaired renal vascular architecture, which can have significant functional consequences. The PKD microvasculature could represent a therapeutic target to decrease the impact of this disease.