Tissue microarrays from bone marrow aspirates for high-throughput assessment of immunohistologic markers in pediatric acute leukemia

Elevated p53 protein expression; a predictor of relapse in rare chronic myeloid malignancies in children?

BACKGROUND

Alterations in the tumor suppressor gene TP53 have been associated with poor outcome in adult hematological malignancies. We have earlier reported an increased expression of the TP53 encoded protein p53, in bone marrow samples from pediatric patients with aggressive leukemia. Our aim was now to evaluate p53 protein expression at different time points before and after hematopoietic stem cell transplantation (HSCT) as a predictor of relapse in a group of children diagnosed with MDS, JMML and CML, and also investigate if potential alterations in expression could be correlated to mutations in TP53.

PROCEDURE

Paraffin embedded bone marrow samples from 33 pediatric patients diagnosed with MDS, JMML and CML between 1997 and 2010 were collected retrospectively from time of diagnosis and pre and post HSCT. Immunohistochemistry (IHC) was performed on tissue microarrays (TMA) with antibodies to p53 and p21. DNA sequencing of exon 2-11 of TP53 was performed in 7 patients with JMML and 5 patients with MDS.

RESULTS

Elevated p53 protein expression at diagnosis predicted for relapse, odds ratio (OR) 1.19 (95% CI: 1.02-1.40, p = .028). Sequencing of TP53 did not reveal any mutations in the 12 patients analyzed and p53 expression correlated positively to p21 expression indicating a functional p53/p21 protein pathway.

CONCLUSION

Elevated p53 protein expression at diagnosis may be an indicator of relapse in children with MDS, JMML and CML.

High-throughput on-chip leukemia diagnosis

Advances in lab-on-a-chip technologies enabled programmable, reconfigurable, and scalable manipulation of a variety of laboratory procedures. Samples, reagents, and fluids can be precisely controlled; buffer temperature, pH, and concentration control systems as well as a variety of detection systems can be integrated on a small chip. These advantages have attracted attention in various fields of clinical application including leukemia diagnosis and research. A lot of research on lab-on-a-chip based diagnosis has been reported and the field is rapidly expanding. This review describes recent developments of lab-on-a-chip technologies as solutions to challenges for high-throughput leukemia diagnosis.

Building "tissue" microarrays from suspension cells

Tissue microarray (TMA) is a highly efficient method that allows for large-scale measurement of -expression of RNA or protein in multiple tissue sections simultaneously. Most TMAs are made from paraffin--embedded tissues. In this chapter, we detail a method that enables construction of TMAs from small volumes of cells in suspension. A TMA is built using pellets of 1 x 10(6) to 5 x 10(7) spun cells after fixation, processing, and embedding. The entire procedure is carried out in a microcentrifuge tube and yields excellent preservation of cytomorphology and immunoreactivity from both fresh and frozen suspension cells. It is particularly useful for the study of hematopoietic neoplasms presenting in the blood and bone marrow, fine needle aspirates, and body fluids as well as cultured cells. In addition, this versatile method may facilitate the exploration of gene expression profiling and protein expression in clinical trials where regular tissue biopsies are not available.