Immunophenotypic characterization of stromal cells in aspirated human bone marrow samples

Area of Science:

• Hematology
• Cell Biology
• Immunology

Background:

• Stromal cells are essential components of the bone marrow microenvironment.
• Human long-term bone marrow culture (hLTBMC) relies on the presence and function of stromal cells.
• Characterizing stromal cells in initial bone marrow aspirates is vital for successful culture initiation.

Purpose of the Study:

• To investigate the presence and characteristics of stromal cells in aspirated bone marrow.
• To evaluate the utility of specific markers for identifying stromal elements in bone marrow aspirates.
• To understand the origin of stromal components in hLTBMC.

Main Methods:

• Immunocytochemical staining of cytocentrifuge preparations from bone marrow aspirates.
• Utilizing antibodies against vascular cell adhesion molecule-1, low-affinity nerve growth factor receptor (NGFR), and alpha-smooth muscle actin.
• Morphological and immunophenotypic assessment of cell populations and tissue fragments.

Main Results:

• Stromal cells expressing vascular cell adhesion molecule-1 and NGFR were identified.
• No cells expressing alpha-smooth muscle actin were detected.
• Multicellular tissue fragments containing various stromal cell types were observed, suggesting explant growth potential.
• Few macrophages were present, indicating their origin from monocytes.

Conclusions:

• NGFR is a valuable marker for identifying stromal elements in aspirated bone marrow.
• The presence of tissue fragments suggests complex origins for hLTBMC stroma.
• Further investigation is needed to determine if CD34+ cells include both stromal and hematopoietic precursors.