Microvascular alterations in transplantation

Endothelial injury and repair are most important concepts for our understanding of renal disease and allograft injury. The concept that injury to the endothelium may precede renal fibrosis strongly suggests that interventions to maintain vascular integrity are of major importance for renal function. This thesis focuses on the mechanisms involved in the process of endothelial damage and repair in renal disease, (early) diabetes mellitus (DM) and renal ischemia-reperfusion (I/R) injury. Furthermore, microvascular alterations were assessed, using sidestream darkfield (SDF) imaging and measurement of endothelial dysfunction markers (including angiopoietins), in chronic kidney disease (CKD) and DM patients before and after (pancreas) kidney transplantation. The results of this thesis demonstrate an important role for endothelial damage and repair in renal disease and after transplantation. Both renal I/R and DM induced systemic capillary damage reflected by increased capillary tortuosity by SDF imaging and a dysbalance in angiopoietins. In addition, patients with CKD and allograft rejection after renal transplantation also had systemic microvascular derangements. Transplantation was effective in reversing the systemic microvascular alterations. Complementary use of SDF imaging to measure microvascular tortuosity and the assessment of endothelial dysfunction markers may be useful diagnostic tool for monitoring the microvasculature before and after transplantation.Nederlandse transplantatie vereniging, Amgen, Roche, Boehringer-Ingelheim, Leids Universitair Medisch CentrumUBL - phd migration 201

Early systemic microvascular damage in pigs with atherogenic diabetes mellitus coincides with renal angiopoietin dysbalance

Background: Diabetes mellitus (DM) is associated with a range of microvascular complications including diabetic nephropathy (DN). Microvascular abnormalities in the kidneys are common histopathologic findings in DN, which represent one manifestation of ongoing systemic microvascular damage. Recently, sidestream dark-field (SDF) imaging has emerged as a noninvasive tool that enables one to visualize the microcirculation. In this study, we investigated whether changes in the systemic microvasculature induced by DM and an atherogenic diet correlated spatiotemporally with renal damage. Methods: Atherosclerotic lesion development was triggered in streptozotocin-induced DM pigs (140 mg/kg body weight) by administering an atherogenic diet for approximately 11 months. Fifteen months following induction of DM, microvascular morphology was visualized in control pigs (n = 7), non-diabetic pigs fed an atherogenic diet (ATH, n = 5), and DM pigs fed an atherogenic diet (DM+ATH, n = 5) using SDF imaging of oral mucosal tissue. Subsequently, kidneys were harvested from anethesized pigs and the expression levels of well-established markers for microvascular integrity, such as Angiopoietin-1 (Angpt1) and Angiopoietin-2 (Angpt2) were determined immunohistochemically, while endothelial cell (EC) abundance was determined by immunostaining for von Willebrand factor (vWF). Results: Our study revealed an increase in the capillary tortuosity index in DM+ATH pigs (2.31±0.17) as compared to the control groups (Controls 0.89±0.08 and ATH 1.55±0.11; p<0.05). Kidney biopsies showed marked glomerular lesions consisting of mesangial expansion and podocyte lesions. Furthermore, we observed a disturbed Angpt2/ Angpt1balance in the cortex of the kidney, as evidenced by increased expression of Angpt2 in DM+ATH pigs as compared to Control pigs (p<0.05). Conclusion: In the setting of DM, atherogenesis leads to the augmentation of mucosal capillary tortuosity, indicative of systemic microvascular damage. Concomitantly, a dysbalance in renal angiopoietins was correlated with the development of diabetic nephropathy. As such, our studies strongly suggest that defects in the systemic microvasculature mirror the accumulation of microvascular damage in the kidney

Microstructure and biomechanical characteristics of bone substitutes for trauma and orthopaedic surgery

Abstract. BACKGROUND: Many (artificial) bone substitute materials are currently available for use in orthopaedic trauma surgery. Objective data on their biological and biomechanical characteristics, which determine their clinical application, is mostly lacking. The aim of this study was to investigate structural and in vitro mechanical properties of nine bone substitute cements registered for use in orthopaedic trauma surgery in the Netherlands. METHODS: Seven calcium phosphate cements (BoneSource®, Calcibon®, ChronOS®, Eurobone®, HydroSet™, Norian SRS®, and Ostim®), one calcium sulphate cement (MIIG® X3), and one bioactive glass cement (Cortoss®) were tested. Structural characteristics were measured by micro-CT scanning. Compression strength and stiffness were determined following unconfined compression tests. RESULTS: Each bone substitute had unique characteristics. Mean total porosity ranged from 53% (Ostim®) to 0.5% (Norian SRS®). Mean pore size exceeded 100 μm only in Eurobone® and Cortoss® (162.2 ± 107.1 μm and 148.4 ± 70.6 μm, respectively). However, 230 μm pores were found in Calcibon®, Norian SRS®, HydroSet™, and MIIG® X3. Connectivity density ranged from 27/cm3 for HydroSet™ to 0.03/cm3 for Calcibon®. The ultimate compression strength was highest in Cortoss® (47.32 MPa) and lowest in Ostim® (0.24 MPa). Young's Modulus was highest in Calcibon® (790 MPa) and lowest in Ostim® (6 MPa). CONCLUSIONS: The bone substitutes tested display a wide range in structural properties and compression strength, indicating that they will be suitable for different clinical indications. The data outlined here will help surgeons to select the most suitable products currently available for specific clinical indications

Microvascular alterations in transplantation

Endothelial injury and repair are most important concepts for our understanding of renal disease and allograft injury. The concept that injury to the endothelium may precede renal fibrosis strongly suggests that interventions to maintain vascular integrity are of major importance for renal function. This thesis focuses on the mechanisms involved in the process of endothelial damage and repair in renal disease, (early) diabetes mellitus (DM) and renal ischemia-reperfusion (I/R) injury. Furthermore, microvascular alterations were assessed, using sidestream darkfield (SDF) imaging and measurement of endothelial dysfunction markers (including angiopoietins), in chronic kidney disease (CKD) and DM patients before and after (pancreas) kidney transplantation. The results of this thesis demonstrate an important role for endothelial damage and repair in renal disease and after transplantation. Both renal I/R and DM induced systemic capillary damage reflected by increased capillary tortuosity by SDF imaging and a dysbalance in angiopoietins. In addition, patients with CKD and allograft rejection after renal transplantation also had systemic microvascular derangements. Transplantation was effective in reversing the systemic microvascular alterations. Complementary use of SDF imaging to measure microvascular tortuosity and the assessment of endothelial dysfunction markers may be useful diagnostic tool for monitoring the microvasculature before and after transplantation

Pharmaco-economic study and cost of care for chronic diseases: Case of Haemophilia in Morocco

This paper is an attempt to enrich the literature about the role that can play some economic approaches, such as cost-effectiveness analysis, in order to help medical stuffs to decide about the treatment to adopt in case of a chronic disease such as Haemophilia. Data from morocco were gathered in order to explain the importance of such approaches

ENDOTHELIAL AND THROMBOCYTE ACTIVATION ARE NOT MEDIATORS IN EARLY ISCHEMIA-REPERFUSION INJURY IN HUMAN KIDNEY TRANSPLANTATION

Nephrolog