Quantification of clonal hematopoiesis in polycythemia vera

Area of Science:

• Hematology
• Oncology
• Genetics

Background:

• Polycythemia vera (PV) is a clonal myeloproliferative neoplasm affecting hematopoietic stem cells.
• Chromosomal abnormalities, such as trisomy 8 or 9, occur in approximately 20% of PV patients.
• Understanding the proportion of neoplastic and non-neoplastic progenitor cells is crucial for PV characterization.

Purpose of the Study:

• To quantify neoplastic and non-neoplastic CD34(+) progenitor cells in Polycythemia vera.
• To investigate the presence and proportion of chromosomal abnormalities in PV patients.
• To evaluate the diagnostic utility of fluorescence in situ hybridization (FISH) in PV.

Main Methods:

• Comparative genomic hybridization (CGH) was used to screen for chromosomal abnormalities in peripheral blood mononuclear cells.
• Fluorescence in situ hybridization (FISH) was applied to quantify cells with trisomy 8 or 9 in enriched cell fractions.
• FISH analysis was also performed on trephine biopsies to assess diagnostic value.

Main Results:

• Two out of ten PV patients showed cytogenetic changes, including trisomy 8 or 9.
• FISH analysis revealed that up to 79% of CD34(+) progenitor cells in these patients carried trisomy 8 or 9.
• FISH on bone marrow biopsies detected trisomies in 10-15% of cells, indicating a distinct non-clonal CD34(+) progenitor cell population.

Conclusions:

• PV exhibits a stem cell character with both clonal and non-clonal CD34(+) progenitor cells.
• The identification of a distinct, non-aberrant CD34(+) progenitor cell population offers potential therapeutic insights.
• FISH analysis of bone marrow biopsies can aid in the diagnosis of early-stage PV.