In vitro models to evaluate acute and chronic injury to the heart and vascular systems

Pancreatic cancer organotypics: High throughput, preclinical models for pharmacological agent evaluation

Pancreatic cancer carries a terrible prognosis, as the fourth most common cause of cancer death in the Western world. There is clearly a need for new therapies to treat this disease. One of the reasons no effective treatment has been developed in the past decade may in part, be explained by the diverse influences exerted by the tumour microenvironment. The tumour stroma cross-talk in pancreatic cancer can influence chemotherapy delivery and response rate. Thus, appropriate preclinical in vitro models which can bridge simple 2D in vitro cell based assays and complex in vivo models are required to understand the biology of pancreatic cancer. Here we discuss the evolution of 3D organotypic models, which recapitulare the morphological and functional features of pancreatic ductal adenocarcinoma (PDAC). Organotypic cultures are a valid high throughput preclinical in vitro model that maybe a useful tool to help establish new therapies for PDAC. A huge advantage of the organotypic model system is that any component of the model can be easily modulated in a short time-frame. This allows new therapies that can target the cancer, the stromal compartment or both to be tested in a model that mirrors the in vivo situation. A major challenge for the future is to expand the cellular composition of the organotypic model to further develop a system that mimics the PDAC environment more precisely. We discuss how this challenge is being met to increase our understanding of this terrible disease and develop novel therapies that can improve the prognosis for patients.

Biological Effects of Clinically Relevant CoCr Nanoparticles in the Dura Mater: An Organ Culture Study

Medical interventions for the treatment of spinal disc degeneration include total disc replacement and fusion devices. There are, however, concerns regarding the generation of wear particles by these devices, the majority of which are in the nanometre sized range with the potential to cause adverse biological effects in the surrounding tissues. The aims of this study were to develop an organ culture model of the porcine dura mater and to investigate the biological effects of CoCr nanoparticles in this model. A range of histological techniques were used to analyse the structure of the tissue in the organ culture. The biological effects of the CoCr wear particles and the subsequent structural changes were assessed using tissue viability assays, cytokine assays, histology, immunohistochemistry, and TEM imaging. The physiological structure of the dura mater remained unchanged during the seven days of in vitro culture. There was no significant loss of cell viability. After exposure of the organ culture to CoCr nanoparticles, there was significant loosening of the epithelial layer, as well as the underlying collagen matrix. TEM imaging confirmed these structural alterations. These structural alterations were attributed to the production of MMP-1, -3, -9, -13, and TIMP-1. ELISA analysis revealed that there was significant release of cytokines including IL-8, IL-6, TNF-α, ECP and also the matrix protein, tenascin-C. This study suggested that CoCr nanoparticles did not cause cytotoxicity in the dura mater but they caused significant alterations to its structural integrity that could lead to significant secondary effects due to nanoparticle penetration, such as inflammation to the local neural tissue.

Drug attrition during pre-clinical and clinical development: understanding and managing drug-induced cardiotoxicity

Cardiovascular toxicity remains a major cause of concern during preclinical and clinical development as well as contributing to post-approval withdrawal of medicines. This issue is particularly relevant for anticancer drugs where, the significant improvement in the life expectancies of patients has dramatically extended the use and duration of drug therapies. Nevertheless, cardiotoxicity is also observed with other classes of drugs, including antibiotics, antidepressants, and antipsychotics. This article summarizes the clinical manifestations of drug-induced cardiotoxicity by various cancer chemotherapies and novel drugs for the treatment of other diseases. Furthermore, it presents on overview of biomarker and imaging techniques for the detection of drug-induced cardiotoxicity. Guidelines for the management of patients exposed to drugs with cardiotoxic potential are presented as well as a checklist for collecting information when a safety signal is observed in clinical trials to more effectively assess the risk of cardiotoxicity and manage patient safety.

How can we improve our understanding of cardiovascular safety liabilities to develop safer medicines?

Given that cardiovascular safety liabilities remain a major cause of drug attrition during preclinical and clinical development, adverse drug reactions, and post-approval withdrawal of medicines, the Medical Research Council Centre for Drug Safety Science hosted a workshop to discuss current challenges in determining, understanding and addressing 'Cardiovascular Toxicity of Medicines'. This article summarizes the key discussions from the workshop that aimed to address three major questions: (i) what are the key cardiovascular safety liabilities in drug discovery, drug development and clinical practice? (ii) how good are preclinical and clinical strategies for detecting cardiovascular liabilities? and (iii) do we have a mechanistic understanding of these liabilities? It was concluded that in order to understand, address and ultimately reduce cardiovascular safety liabilities of new therapeutic agents there is an urgent need to: • Fully characterize the incidence, prevalence and impact of drug-induced cardiovascular issues at all stages of the drug development process. • Ascertain the predictive value of existing non-clinical models and assays towards the clinical outcome. • Understand the mechanistic basis of cardiovascular liabilities; by addressing areas where it is currently not possible to predict clinical outcome based on preclinical safety data. • Provide scientists in all disciplines with additional skills to enable them to better integrate preclinical and clinical data and to better understand the biological and clinical significance of observed changes. • Develop more appropriate, highly relevant and predictive tools and assays to identify and wherever feasible to eliminate cardiovascular safety liabilities from molecules and wherever appropriate to develop clinically relevant and reliable safety biomarkers.

Tubulin ligands suggest a microtubule–NADPH oxidase relationship in postischemic cardiomyocytes

Alterations of the microtubule network, which is involved in many vital processes, occur in several pathological conditions, such as cardiac ischemia. However, the connection between the microtubule assembly state and the factors affecting myocardial reperfusion injury, especially oxidative stress, is unknown. We aimed thus to study the effects of different tubulin ligands on the changes in the microtubule network and in several markers of cell injury and oxidative activity in cardiac muscle cells submitted to a reversible substrate-free, hypoxia-reoxygenation model of ischemia-reperfusion. The microtubule network was visualized by immunocytochemistry. Cell injury was evaluated via lactate dehydrogenase release and the mitochondrial function by the MTT test. Superoxide production was detected using dihydroethidium. The activity of NADPH oxidase and mRNA subunit expression were investigated. The microtubule disassembly induced by simulated ischemia was reversed by placing cardiomyocytes under normoxic conditions. This post-"ischemic" restoration of microtubule assembly was modulated by microtubule stabilizers (taxol: paclitaxel) and by microtubule disrupting drugs (nocodazole, colchicine). In addition, nocodazole decreased superoxide anion production as well as NADPH oxidase activity and mRNA expression of the NADPH oxidase subunit p22phox. These results demonstrated that the "ischemia"-induced microtubule network alteration is reversible and suggest a possible relationship between "reperfusion"-induced reassembly of microtubules and free radical generation in post-"ischemic" cardiomyocytes.