The IKDT performs diagnostic tests for detection of inflammatory processes or viral infection of human myocard biopsies under stringent compliance of FDA guidelines. The diagnostic spectrum includes histology, immunhistochemical analysis and PCR assays for detection of viral genomes. Myocardial biopsies in native or fixed form are the preferred sample materials for these tests. For suitable assays and results it is important that the submitted material undergoes a well defined pre-analytic treatment.
For endomyocardial biopsies should be used a novel reagent for conservation by ambient temperature. RNAlater is an aqueous, non-toxic tissue storage reagent that stabilizes and protects cellular RNA in intact, unfrozen tissue samples. RNAlater eliminates the need to immediately process tissue samples or to freeze samples in liquid nitrogen for later processing. RNAlater is also suitable for preparation for genomic DNA, histological examination and immunohistochemistry. Tissue pieces can be harvested and submerged in RNAlater for storage without jeopardizing the quality or quantity of RNA obtained after subsequent RNA isolation. RNAlater can be added to cell pellets and even cells in medium. The samples can then be stored frozen or unfrozen.
The endomyocardial biopsies (less than 0.5 cm in any one dimension) are simply submerged in approximately 0.5 ml of RNAlater at room temperature. Please submerge biopsies by inverting tube 5 times. The solution permeates the cells, stabilizing the RNA. Preferably, samples should be sent directly at ambient temperature to IKDT lab or stored at +4°C before transport.. The transport could be performed in a padded envelope by conventional mail. After reception in IKDT lab, the sample will be stored at +4°C for one night and then can be stored at 4°C for up to a month or at 25°C for up to a week or at -20 to -80°C indefinitely (the tissue does not freeze).
Never freeze or treat the biopsies by other fixatives before RNAlater fixation!
RNAlater is only suitable for very small tissue samples (biopsies). Larger piece (explanted heart samples) has to be divided rapidly in small aliquots or should be cryo-conserved in liquid nitrogen.