Faculty Bibliography

BACKGROUND:Cardiovascular disease is the leading cause of premature mortality in autosomal dominant polycystic kidney disease (ADPKD). We examined peripheral augmentation index (AIx) as a measure of systemic vascular function and circulating markers of vascular inflammation in patients with ADPKD. METHODS:Fifty-two ADPKD patients with hypertension and estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2), 50 ADPKD patients with hypertension and eGFR ≥ 60 mL/min/1.73 m(2), 42 normotensive ADPKD patients with eGFR ≥ 60 mL/min/1.73 m(2) and 51 normotensive healthy controls were enrolled in this study. AIx was measured from peripheral artery tone recordings using finger plethysmography. Serum levels of soluble intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule-1, P-selectin, E-selectin, soluble Fas (sFas) and Fas ligand (FasL) were measured as markers of vascular inflammation. RESULTS:AIx was higher in all three patient groups with ADPKD compared to healthy controls (P < 0.05). AIx was similar between the normotensive ADPKD patients with eGFR ≥ 60 mL/min/1.73 m(2) and hypertensive ADPKD patients with eGFR < 60 mL/min/1.73 m(2) (P > 0.05). ICAM, P-selectin, E-selectin and sFas were higher and FasL lower in all ADPKD groups compared to controls (P < 0.05). ICAM, P-selectin and E-selectin were similar between the normotensive ADPKD patients with eGFR ≥ 60 mL/min/1.73 m(2) and hypertensive ADPKD patients with eGFR < 60 mL/min/1.73 m(2) (P > 0.05). According to multiple regression analysis, predictors of AIx in ADPKD included age, height, heart rate and mean arterial pressure (P < 0.05). Vascular inflammatory markers were not predictors of AIx in ADPKD. CONCLUSIONS:Systemic vascular dysfunction, manifesting as an increase in AIx and vascular inflammation is evident in young normotensive ADPKD patients with preserved renal function. Vascular inflammation is not associated with elevated AIx in ADPKD.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Most deaths in autosomal dominant polycystic kidney disease (ADPKD) are attributable to cardiovascular disease (CVD). We examined novel CVD biomarkers in different stages of ADPKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS/METHODS:We recruited 50 hypertensive subjects with ADPKD with estimated GFR (eGFR) of >60 ml/min per 1.73 m(2); 52 hypertensive subjects with ADPKD with eGFR of 25 to 60 ml/min per 1.73 m(2); 42 normotensive subjects with ADPKD and eGFR of >60 ml/min per 1.73 m(2); and 50 healthy controls. We assayed serum C-reactive protein and IL-6 as markers of inflammation; plasma 8-epi-prostaglandin F(2α (8-epi-PGF2α)) and superoxide dismutase (SOD) as markers of oxidative stress; and homeostasis model assessment (HOMA) as a measure of insulin resistance. RESULTS:The hypertensive ADPKD eGFR of 25 to 60 group had higher levels of C-reactive protein and IL-6 than controls, normotensive ADPKD with eGFR of >60, and hypertensive ADPKD with eGFR of >60. The normotensive ADPKD eGFR >60, hypertensive ADPKD eGFR >60, and hypertensive ADPKD eGFR 25 to 60 groups had higher 8-epi-PGF(2α) and lower SOD than controls, with no difference between the ADPKD groups. There was no difference in HOMA levels between any of the groups. Adjustment for age, race, gender, and body mass index did not alter these relationships. CONCLUSIONS:Inflammation and oxidative stress are evident early in ADPKD even with preserved kidney function. Inflammation exhibits a graded relationship with levels of kidney function, whereas oxidative stress demonstrates a threshold effect. These pathways may be therapeutic targets for CVD risk mitigation.

Morphogenesis of epithelial cells involves processes by which kidney shape and function are regulated. The lack of in vitro models that are sustainable for longer time periods and emulating complex intercellular interactions of the kidney have limited understanding about epithelial tissue morphogenesis and its aberrations in diseases such as autosomal dominant polycystic kidney disease (ADPKD). A sustainable three-dimensional (3D) coculture system for normal and diseased kidney tissues is reported here. Tubule- and ADPKD cyst-derived cells were cultured in extracellular matrix molecules infused into 3D porous silk scaffolds, and these cultures were subsequently extended into a perfusion bioreactor. The results indicated collagen-matrigel-mediated morphogenesis for both (normal and disease) cell types and also supported coculturing with fibroblasts. The structural and functional features of the kidney-like tissue structures were validated based on the distribution of E-cadherin, N-cadherin, Na+ K+ ATPase pump, and cellular uptake of the organic anion (6-carboxy fluorescein). Further, the structures were sustained for longer time periods using a perfusion bioreactor to demonstrate the potential utility of this 3D in vitro coculture system for ADPKD research, other epithelial tissue systems, and for in vitro drug screening.

Three-dimensional porous scaffolds prepared from regenerated silk fibroin using either an all-aqueous process or a process involving an organic solvent, hexafluoroisopropanol (HFIP), have shown promise in cell culture and tissue engineering applications. However, their biocompatibility and in vivo degradation have not been fully established. The present study was conducted to systematically investigate how processing method (aqueous vs. organic solvent) and processing variables (silk fibroin concentration and pore size) affect the short-term (up to 2 months) and long-term (up to 1 year) in vivo behavior of the protein scaffolds in both nude and Lewis rats. The samples were analyzed by histology for scaffold morphological changes and tissue ingrowth, and by real-time RT-PCR and immunohistochemistry for immune responses. Throughout the period of implantation, all scaffolds were well tolerated by the host animals and immune responses to the implants were mild. Most scaffolds prepared from the all-aqueous process degraded to completion between 2 and 6 months, while those prepared from organic solvent (hexafluoroisopropanol (HFIP)) process persisted beyond 1 year. Due to widespread cellular invasion throughout the scaffold, the degradation of aqueous-derived scaffolds appears to be more homogeneous than that of HFIP-derived scaffolds. In general and especially for the HFIP-derived scaffolds, a higher original silk fibroin concentration (e.g. 17%) and smaller pore size (e.g. 100-200microm) resulted in lower levels of tissue ingrowth and slower degradation. These results demonstrate that the in vivo behavior of the three-dimensional silk fibroin scaffolds is related to the morphological and structural features that resulted from different scaffold preparation processes. The insights gained in this study can serve as a guide for processing scenarios to match desired morphological and structural features and degradation time with tissue-specific applications.