Making sense out of in situ PCR

Given the limited sensitivity of existing in situ hybridization methods for detecting specific nucleic acid sequences, amplification in situ by means of the polymerase chain reaction (PCR) seems to be an attractive alternative. Recent studies using in situ PCR technology have not assessed the gain in signal strength that has been achieved, nor evaluated quantitatively the efficiency of amplification. An accompanying article in the current issue of the Journal examines the reproducibility and amplification efficiency of an RT-PCR in situ hybridization method that uses a sense probe, capable of detecting only amplified target sequences. The amplification procedure resulted in approximately 3-6-fold increased sensitivity that depended upon cell type and disease status.