MESSENGER-RNA PHENOTYPING FOR STUDYING GENE-EXPRESSION IN SMALL NUMBERS OF CELLS - PLATELET-DERIVED GROWTH-FACTOR AND OTHER GROWTH-FACTORS IN WOUND-DERIVED MACROPHAGES

The understanding of biologic and pathophysiologic processes in lung is aided by a technique for ascertaining the transcriptional phenotype of small numbers of cells examined in vivo. The mRNA phenotyping procedure consists of scaled-down methods for isolating mRNA from small numbers of cells, followed by reverse transcription of the RNA and specifically primed amplification of the cDNA by the polymerase chain reaction. We show an example of the use of the technique in a study of expression of platelet-derived growth factor and other growth factor genes in macrophages isolated from wound cylinders implanted in mice. With this technique, the transcriptional phenotype of purified normal lung epithelial and mesenchymal cells, macrophages, or cells obtained from lavaged lungs or punch biopsy specimens can be examined as a rapid first step in understanding molecular processes in the lung.