Specialists of the Central Administrative Board of Research Institute of Experimental Medicine (Russian Academy of Medical Sciences) are developing express method for early detection of diabetic nephropathy. Their effort has been funded through the grant of the President of the Russian Federation.

Specialists of the Central Administrative Board of Research Institute of Experimental Medicine (Russian Academy of Medical Sciences) are developing biological microchip that will allow to detect a very early stage of diabetic nephropathy - one of heavy complications of insular diabetes. They have created a preliminary version of biochip, which possesses high sensitivity and allows to analyze simultaneously at least 30 to 50 tests.

At present, more than one hundred million people worldwide suffer from diabetes, including more than 2 million people in Russia. According to the World Health Organization (WHO) data, the number of new morbid events increases annually by 7 to 12 percent and redoubles every 6 to 7 years.

Every third patient who needs chronic hemodialysis or renal transplantation is a person suffering from insular diabetes. Early detection and timely medical treatment are necessary in this case, but diagnostics should be noninvasive, inexpensive, trustworthy and easy to perform.

Biological microchip technology, which has been commonly applied in recent years in biology, medicine and biotechnology, meets these requirements.
Biochip is a special carrier where various biological molecules, DNA or albumens are placed in certain order. A large number of molecules of various substances are placed on a small square of biochip. When placed in the test, these biological molecules react with others, and the locations of reaction are marked with a luminous marker. The information is read off the biochip with the help of special recording system.

For early detection of diabetic nephropathy physicians need to catch very low concentrations of albumin in urine (at the pre-clinical stage of the disease, kidneys excrete from 30 to 300 milligrams of this albumen per day).

A fragment of genetically engineered albumen G, which binds human albumin, is applied on the microchip (a porous plate, it square being one and a half centimeter by one and a half centimeter). This albumen is obtained in the Institute of Experimental Medicine. 30 to 50 albuminous spots can be placed on a plate. Then a patient's urine test is applied to each spot and the microchip is processed by labeled albumen, which colors only albumin. If the test is colored, it means that the patient is ill with nephropathy.

The carrier itself constitutes monolithic macroporous sorbent, the pores'
size being 800 nm, this is a polymer of glycidyl methacrylate, produced at the Institute of High-Molecular Compounds (Russian Academy of Sciences) under the guidance of T.B. Tennikova, Doctor of Science (Chemistry). The polymer contains functional epoxy groups, which allow to bind biological molecules in mild conditions. That significantly increases sorptive capacity of the material, which is approximately one hundred times higher than the capacity of a traditional material- nitrocellulose membrane. Thus, analysis sensitivity would increase.
Pilot experiments have proved that biochip allows to record 20 mkg of albumin in 1 milliliter of urine. That is sufficient for diagnosing.

However, when treating nephropathy, physicians need to track changing of albumin content in urine. Then, precise quantitative data logging will be needed, and to this end, recording system for information read-out from biochip matrix is required. That is why the researchers intend to create in the future a convenient and inexpensive carrier reading system, which will allow to precisely assess the content of albumin in urine. Besides, the system will also be used for other diagnostic test-systems.
Natalia Reznik

Further information: St. Petersburg; Central Administrative Board of Research Institute of Experimental Medicine, Russian Academy of Medical Sciences, E.N. Rakhmatullina, katusharurkhm@mail.ru