Biomedical Engineering Reference
In-Depth Information
14
Nucleic-acid- and cell-based
therapeutics
14.1 Introduction
Throughout the 1980s and early 1990s, the term 'biopharmaceutical' had become virtually synon-
ymous with 'proteins of therapeutic use' (Chapter 1). Nucleic-acid-based biopharmaceuticals, too,
harbour great potential. Current developments in nucleic-acid-based therapeutics centre around
gene therapy, as well as antisense technology (including RNAi) and aptamer technology, all of
which are discussed later in this chapter. These technologies have the potential to revolution-
ize medical practice. Despite all the hype, however, it is important to note that by early 2007 at
least, only three nucleic-acid-based products had gained approval worldwide: one antisense-based
product (tradename Vitravene), one aptamer (tradename Macugen) and one gene therapy product
(tradename Gendicine, approved only in China). In contrast, some 165 protein-based biopharma-
ceuticals had been approved by early 2007. The full benefi t of nucleic-acid-based medicines will
accrue only after the satisfactory resolution of several technical diffi culties currently impeding
their routine medical application.
Cell-based medicines also harbour tremendous potential. Although a small number of such
products have gained approval, none is a stem-cell-derived product. Cell-based biopharmaceuti-
cals are discussed towards the end of this chapter.
14.2 Gene therapy
The fundamental principle underpinning gene therapy is theoretically straightforward, but dif-
fi cult to achieve in practice satisfactorily. The principle entails the stable introduction of a gene
into the genetic complement of a cell, such that subsequent expression of the gene achieves a thera-
peutic goal. The potential of gene therapy as a curative approach for inborn errors of metabolism
and other conditions induced by the presence of a defective copy of a specifi c gene (or genes) is
obvious.
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