Fresh-frozen, optimal cutting temperature (OCT) compound-embedded bone marrow aspirates: a reliable resource for morphological, immunohistochemical and molecular examinations

The usefulness of fresh-frozen, optimal cutting temperature (OCT) compound-embedded (FFOE) bone marrow (BM) aspirates was evaluated as a reliable resource for morphological, immunohistochemical and molecular examinations. One hundred BM aspirates were collected in polypropylene tubes and immediately frozen for 2 h in a deep freezer. Frozen BM was transferred to a cryomold filled with OCT compound and the prepared samples were stored in a deep freezer. Histological examination and immunohistochemical staining, polymerase chain reaction (PCR), sequencing and reverse transcription (RT)-PCR were performed to evaluate the quality of the FFOE BM sections in 10% of randomly selected samples. FFOE BM sections revealed better morphologies than paraffin-embedded clot sections in haematoxylin and eosin staining because mature erythrocytes were removed during the staining process in frozen BM sections. Immunohistochemical staining for CD34 revealed excellent staining quality and oil red O staining showed that fat vacuoles in cells were well preserved. The quality of genomic DNA in FFOE BM sections was suitable for obtaining about 2000 bp PCR product for the human leucocyte antigen-A locus followed by direct sequencing of the sample, and the quality of total RNA was suitable for detection of BCR-ABL fusion transcript. FFOE BM aspirates are a reliable resource for various laboratory tests of diagnostic and research arenas.