Biosensor technology in the treatment of cardiovascular disease - Biomaterials and Devices for the Circulatory System - page 289

microarray chips and through hybridisation can detect a range of genes
simultaneously. Hybridisation with the target genes is detected by fl uores-
cent methods and a map of gene expression is produced.
Genetic studies have identifi ed marker genes for various aspects of car-
diovascular disease, and, as knowledge of the human genome grows, the
future will yield more. 19,24 Personal risk profi les for cardiovascular disease
could be produced. Microarray techniques have been used to study the
genetic basis of vascular dysfunction, atherogenesis, pulmonary hyperten-
sion, myocardial infarction, hypertrophy, heart failure, cardiovascular
infl ammation and cardiac metabolism in animals (mainly rats and mice) and
also in humans. Various gene pathways have been identifi ed by microarray
in endothelial and smooth muscle cell processes that contribute to athero-
genesis. In relation to hypertension, information on the gene profi les of
spontaneously hypertensive rats has been obtained using microarray tech-
nology. 25 Microarray investigation of myocardial infarction in rats has
found that the expression of more than 200 out of 4000 genes was altered. 26
Human applications of microarray technology have included the develop-
ment of a cDNA microarray for the identifi cation of genes that are expressed
differently in heart failure. 27 Profi ling the gene expression of circulating
platelets has led to the identifi cation of myeloid-related protein 14 (MRP14),
which is differentially expressed in patients with AMI and stable coronary
artery disease, as a biomarker for risk of future cardiovascular events. 28
Microarrays based on the antibodies to various cardiovascular risk
markers have also been developed. 29 These antibody microarrays allow the
simultaneous measurement of the serum levels of a range of pertinent
proteins from a small sample. An array of antibodies is immobilised on a
solid membrane to which the target proteins are bound. In some microar-
rays, all the proteins in the sample are labelled (direct labelling immunoas-
says) and in others the unlabelled proteins are captured by the immobilised
antibodies and subsequently detected using labelled detection antibodies
(sandwich-type immunoassays). In both cases, the amount of bound protein
is quantifi ed using fl uorescence methods. Protein markers that are impor-
tant for the diagnosis of cardiovascular disease include C-reactive protein,
TNF

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, serum amyloid-A and fatty acid binding protein, which are all
markers of infl ammation.
Biosensor-based point-of-care devices are also useful in the operating
theatre to monitor patient blood gases, metabolites and coagulation during
surgery. 30 Haemorrhage is a major cause of adverse outcome post-surgery,
and the monitoring of coagulation is clinically very useful for patient care
during and after cardiopulmonary bypass. 31 Commercially available devices
include the CoaguChek Pro DM (Roche Diagnostics, Indiana, USA). More
use could potentially be made of POC devices during cardiac surgery if the
technology were more readily available. 32 One area where the advantages

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