Autologous Bone Marrow Transplantation - Blog Science Connections

Digital Image Analysis System for Detection of
Infrequent Cells in Bone Marrow
C. Patrick Reynolds, Benjamin R. Lee, and David B. Haseman
One danger inherent in autologous bone marrow transplantation is the
possibility of reinfusing malignant cells with the marrow. This has led to
development of various methods for purging malignant cells from marrow
harvested for transplantation (1 -5). To assess the efficacy of such purging
procedures requires methods that can detect very small numbers of
malignant cells in bone marrow (6). Antibodies that bind to malignant cells
but not to normal marrow cells have been used to detect small numbers of
malignant cells in blood or marrow using flow cytometry or manual
microscopy (Table 1 ). Some of these assays are capable of detecting as few
as 1 malignant cell per 100,000 marrow cells. The sensitivity of such assays is
limited by several factors, the most important being the number of cells
analyzed for each specimen and the number of false-positive and falsenegative
signals generated by the assay.
We sought to develop an instrument that would improve sensitivity in
detecting minimal disease in bone marrow. To avoid false-positive results the
system should have a means of confirming positive signals as true tumor
cells. Furthermore, to avoid false-negative results the system would need to
avoid excluding clumps of cells (a problem with flow cytometry). Finally, the
system would need to analyze a large enough number of cells to provide the
desired sensitivity in a short enough period of time to be practical. We
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