SPECTRAL IMAGING IN PRECONCEPTION PREIMPLANTATION GENETIC DIAGNOSIS OF ANEUPLOIDY - MULTICOLOR, MULTICHROMOSOME SCREENING OF SINGLE CELLS/

Purpose: Our purpose was to evaluate the utility of spectral imaging f or multicolor; multichromosome enumeration in human interphase cell nu clei. Methods: Chromosome-specific probes labeled with different fluor ochromes or nonfluorescent haptens were obtained commercially or prepa red in-house. Metaphase spreads, interphase lymphocytes, or blastomere s cells were hybridized with either 7 or II distinctly different probe s. Following 46 hr of hybridization, slides were washed and detected u sing either a filter-based quantitative image processing system (QUIPS ) developed in-house or a commercial spectral imaging system. Results: The filter-based fluorescence microscope system is preferred for simu ltaneous detection of up to seven chromosome targets because of its hi gh sensitivity and speed. However; this approach may not be applicable to interphase cells when II or more targets need to be discriminated. Interferometer-based spectral imaging with a spectral resolution of a pproximately 10 nm alloys labeling of chromosome-specific DNA probes w ith fluorochromes having greatly overlapping emission spectra. This le nds to increases in the number of fluorochromes or fluorochrome combin ations available to score unambiguously chromosomes in interphase nucl ei. Conclusions: Spectral imaging provides a significant improvement o ver conventional filter-based microscope systems for enumeration of mu ltiple chromosomes in interphase nuclei, although further technical de velopment is necessary in its application to embryonic blastomeres, Wh en applied to preconception/preimplantation genetic diagnosis, present ly available probes for spectral imaging are expected to detect abnorm alities responsible for 70-80% of spontaneous abortions caused by chro mosomal trisomies.