Purification of cardiac myocytes from human heart biopsies for gene expression analysis

challenging, however, due to tissue availability and sample quality. An additional concern for researchers is deciding the method of RNA extraction from samples. Typically, RNA is extracted from either whole biopsies or from isolated cardiac myocytes, each of which has advantages and disadvantages. To determine gene expression in cardiac myocytes, many researchers use isolated cell methods for extracting RNA. One of these methods involves isolating live cardiac myocytes and individually picking them using a micromanipulator and micropipette for use in gene expression studies. This method can be useful and eliminates contamination of other cell types; however, gene expression could be altered by either the isolation technique (harsh digestions) or during the often lengthy time of cell culture. This method may also not yield accurate results for global gene expression changes since only a small number of cells are sampled. Since it has been shown that transcript levels differ between the areas of the heart (7, 19), comparing cells isolated from different areas may also be problematic. Similarly, single myocytes can be selected via laser capture microdissection from tissue slices (12, 14). While this method is a precise way to obtain single, pure cells from a tissue section, it can be time consuming to collect the cells and the equipment is costly. Although the small number of collected cells may not be representative of the whole biopsy or organ, this method can be very beneficial if a specific population of cells, such as the area of infarction, is the basis of study.