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Chromosomes, each containing hundreds or thousands of genes, act like a detailed instruction manual for how cells should develop and behave. The human genome is made up of 23 chromosome pairs containing more than 3 billion base pairs of DNA, but even the smallest mutation or variation in the structure of a chromosome can have an enormous impact on human development and disease.
To fully understand the range of diseases linked to errors in cell division, scientists must be able to examine in detail both healthy and diseased chromosomes. Better imaging and understanding of chromosomal mechanisms will increase knowledge of the causes of human diseases and aid drug discovery. The EU-funded CHROMAVISION project is addressing this challenge.
The project’s researchers have developed a breakthrough imaging and manipulation platform that enables molecular biologists to zoom in on minuscule details of chromosomes in all their complexity. It will allow scientists to automatically isolate individual chromosomes from small tissue or cell samples and have them delivered to a super-resolution microscope.
‘Chromosomal abnormalities are characteristic of many disorders such as cancer, impaired fertility due to maternal ageing, and neurological disorders such as fragile X syndrome,’ says CHROMAVISION project coordinator Gijs Wuite at Vrije Universiteit Amsterdam. ‘We are therefore aiming to greatly improve images of chromosomes in order to understand these abnormalities and the many important diseases that arise from faulty chromosome segregation.’
Single-molecule manipulation
Chromosomal abnormalities are usually most clearly revealed during the metaphase stage of the cell life cycle, when chromosomes are thickened and condensed just before cell division. The CHROMAVISION researchers therefore focused on developing novel solutions to automatically isolate individual metaphase chromosomes from tissue and cell samples.
The approach makes use of a number of cutting-edge single-molecule manipulation techniques. These include an innovative opto-fluidic chip – a lab-on-a-chip device capable of isolating chromosomes from other cellular material – and optical tweezers to capture and manipulate the individual chromosomes. Isolated chromosomes can then be imaged in 3D via super-resolution fluorescent microscopy.
Combined, these tools form the Super-Resolution Correlative Tweezers Fluorescence Microscope, a device for chromosomal imaging commercialised by industrial project partner Lumicks, a spin-off from Vrije Universiteit Amsterdam which supplies dynamic single-molecule analysis instruments to researchers.
High-resolution 3D images will enable researchers to study chromosomes in extraordinary detail, addressing key challenges in clinical and fundamental research and potentially resulting in breakthrough discoveries through the identification of abnormalities that could be associated with disease.
3D, super-resolution, real-time images
‘This instrument will, for the first time, enable 3D, super-resolution, real-time metaphase chromosome observation and manipulation studies under near-physiological conditions,’ says Wuite. ‘The tools and workflow for imaging metaphase chromosomes are now more or less finished and we are actively working on demonstration projects to illustrate the power of the combination of techniques.’
The platform will also have significant clinical value, allowing the identification and monitoring of cancer heterogeneity, the genomic instability and diversity of tumours that can make them resistant to treatment.
‘Better imaging and understanding of the chromosomal mechanisms will greatly expand our knowledge of the causes and origins of human diseases and will assist in drug discovery and the development of new treatments,’ Wuite says.