Feeder-free and serum-free in vitro assay for measuring the effect of drugs on acute and chronic myeloid leukemia stem/progenitor cells.

Research on chronic and acute myeloid leukemia (CML/AML) is focused on the development of novel therapeutic strategies to eliminate leukemic stem/progenitor cells that are responsible for drug resistance and disease relapse. Methods to culture hematopoietic stem/progenitor cells (HSPCs) from blood or bone marrow samples are indispensable for investigating disease pathogenesis and delineating drug responses in individual patients. A key challenge in this area is that primary leukemic cells grow poorly in culture or rapidly differentiate and lose their hematopoietic potential. Access to patient samples can also be limiting or cell numbers too low to enable large-scale assays and/or to obtain reproducible quantitative data. Here we describe a feeder cell-free and serum-free liquid culture system for the expansion of CD34+ HSPCs from CML/AML samples and healthy control tissues. Following 7 or 14 days of culture, CD34+ cells are expanded 30- to 65-fold or 400- to 800-fold, yielding a purity of ∼80% and ∼60% CD34+ cells, respectively. This system was adapted to a 96-well format to measure the sensitivity of leukemic and normal HSPCs to cytotoxic drugs after only 7 days. The assay requires only 103 cells per well to determine drug IC50 values and can be performed with uncultured and culture-expanded cells. Importantly, resulting IC50 values strongly correlate with those obtained in the classic colony-forming unit (CFU) assay. Compared with the CFU assay, this novel 96-well liquid-based assay designed specifically for leukemic and normal HSPCs is faster and simpler, with more flexible readout methods for selecting candidates for further drug development.

Automation, Monitoring, and Standardization of Cell Product Manufacturing.

Although regenerative medicine products are at the forefront of scientific research, technological innovation, and clinical translation, their reproducibility and large-scale production are compromised by automation, monitoring, and standardization issues. To overcome these limitations, new technologies at software (e.g., algorithms and artificial intelligence models, combined with imaging software and machine learning techniques) and hardware (e.g., automated liquid handling, automated cell expansion bioreactor systems, automated colony-forming unit counting and characterization units, and scalable cell culture plates) level are under intense investigation. Automation, monitoring and standardization should be considered at the early stages of the developmental cycle of cell products to deliver more robust and effective therapies and treatment plans to the bedside, reducing healthcare expenditure and improving services and patient care.

Hematopoietic colony-forming cell assays.

Hematopoiesis is the process by which stem cells divide and differentiate to produce the multiple types of mature cells found in blood. The process begins in early embryonic development and continues throughout adult life, primarily in the bone marrow. Various in vivo and in vitro assays have been developed to detect and assess stem cells and early multi-potential progenitors. While highly informative about primitive hematopoietic cells these assays are long and labour intensive. Alternatively, colony-forming cell (CFC) assays may be used to quantify more lineage-restricted progenitors in a simple in vitro assay. When cultured in a semi-solid medium containing the appropriate cytokines, CFCs are able to divide and differentiate into a colony of more mature cells that can be detected by light microscopy. This allows for the quantification of erythroid, myeloid, lymphoid, megakaryocytic, and multi-potential cell lineages from various cell sources. This chapter outlines the materials and methods used for the culture and assessment of CFC from humans, mice, and other species.