Nanomagnetic genes
Scientists at Emory University (Georgia), working under the guidance of Dr. Xiaoping Hu, have created genetically modified mammalian cells capable of synthesizing magnetic nanoparticles using a gene of a bacterium sensitive to a magnetic field.
The gene used belongs to a pond-dwelling bacterium that uses it to synthesize tiny magnetic particles that act as an arrow of a biological compass.
The authors embedded this gene in the DNA of mouse cells, as a result of which they began to synthesize their own nanomagnets.
When such cells were introduced into the brain of a live mouse, the magnetic resonance imaging method made it possible to clearly distinguish the modified cells as dark specks against the background of light normal body tissue.
(In the figure, the cluster of magnetically active cells is indicated by an arrow.)
To observe cells in the body, scientists usually use genetically modified fluorescent optical markers, such as a green fluorescent protein. A clear regulation of the location of the embedding of the gene of this protein allows scientists to mark proteins of interest in order to observe changes in gene expression and the behavior of certain cell types.
Unlike fluorescence microscopy, the possibilities of which are limited to the study of the surface tissues of living objects, magnetic resonance imaging allows you to study the deep tissues of the body, therefore, the method proposed by the authors can provide doctors and researchers with important additional information about the processes occurring in the body, starting from the formation of tumors and ending with the migration of stem cells introduced for therapeutic purposes.
One of the earlier approaches is the introduction into the body of cells previously incubated with magnetic nanoparticles. However, over time, due to cell division, the signal emitted by them weakens and disappears. Another recently proposed technique is to embed a gene encoding ferritin, a compound used by cells to accumulate iron, into the DNA of a cell. However, iron, which is part of ferritin, is registered much worse than magnetic nanoparticles.
Along with the obvious advantages, the proposed method has its drawbacks. Due to the limitations imposed by the physical processes underlying the MRI method, the images obtained with its help will never match the resolution quality of the images obtained with the help of surface optical microscopy. Moreover, the magnetic properties of nanoparticles need to be studied in detail in order to avoid possible side effects.
However, despite everything, experts believe that the proposed approach opens up a number of possibilities: from new methods of cell imaging to the use of bacteria as biological factories for the production of nanoparticles.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of TechnologyReview
19.06.2008