(104f) Visualizing the Heterogeneity within Primary Hematopoietic Cell Populations with Self-Organizing Maps of Secondary Ion Mass Spectrometry Data

Directing hematopoietic stem cells (HSCs) harvested from bone marrow to self-renew or differentiate into specific hematopoietic cell populations in ex vivo cultures would enable obtaining desired types of blood and immune cells that can be used to treat blood diseases. Due to the rarity of HSCs in the body, micro-cultures that minimize the number of HSCs required to screen the effects of stimuli on HSC fate decisions have been developed. However HSC subpopulations exhibit high cell-to-cell heterogeneity, so the full range of HSC fate decisions that occur in vivo would only be observed if the micro-culture contains a sufficient number of HSCs. Thus, characterizing the heterogeneity within HSC subpopulations is essential for designing artificial cultures for tissue engineering applications. In this study, we assessed whether self-organizing maps (SOMs) of single cell time-of-flight secondary ion mass spectrometry (TOF-SIMS) data that encodes for the biomolecules on the cells’ surfaces, could be used to visualize the heterogeneity between and within three hematopoietic cell populations, including, hematopoietic stem and progenitor cells (HSPCs), lineage-committed common lymphoid progenitors (CLPs), and fully differentiated B cells. The SOMs of TOF-SIMS data from B cells, CLPs, and HSPCs that were isolated from mice show the less differentiated CLP and HSPC populations are more heterogeneous than the highly differentiated B cells. Additionally, unlike the B cells, the CLPs and HSPCs exhibited significant age-related within-population heterogeneity. This assessment demonstrates that SOMs of single-cell spectra could be utilized to probe the heterogeneity between and within hematopoietic cell populations and provide insight into functional differences that exists within these distinct cell populations.