Safety of cell therapy is very important for medicine, and researchers from Russia faced a great challenge – they decided to find out whether stem cells, a common tool of genetic engineering and basics of cell therapy, were genetically stable. Well, stem cells showed quite high level of genetic variability, thus making results of cell therapy ambiguous.

Stem cells are alpha and omega of any type of cell therapy. These cells are usually extracted from donor tissues, but the number of cells from bone marrow, fat tissue, cord blood or other sources is too low for using them for treatment. Before any stem cell enters patient’s organism, cell culture is as a rule grown for some time on a nutrient medium in order to increase cell numbers, to orient cells for desired specialization and to purify them from non-stem cells. Scientists form Moscow performed a very important research, showing that while cells grow on a nutrient medium, their chromosome set doesn’t remain unchanged. In other words, stem cells are genetically unstable.

Studies of foreign molecular biologists revealed that long-term cultivation of mesenchymal stem cells did not affect their genetic stability. As for stem cells, originating from cord blood, they also showed no signs of chromosome variability. However, some scientists claim that after some cultivation mesenchymal stem cells start behaving like tumor cells – laboratory mice, which were injected with such cells, suffered from large number of neoplasms. Embryonic stem cells, which generate even a stronger scientific interest then their “colleagues” from adult donors, are yet not allowed to use with medical purposes, but scientists cannot wait until governments issue a permissive law. Cultures of embryonic stem cells are considered to be genetically stable, however, some researchers showed that under conditions of long-term cultivation cells with chromosome rearrangements appear, and such cells proliferate successfully.

 

 

Geneticists from Moscow used all existing molecular biology techniques to analyze 26 cultures of mesenchymal stem cells, 19 cultures of stem cells form fat tissues and 7 lines of bone marrow stem cells. Researchers found out that during cultivations of cells their chromosomes were often lost or deformed, moreover, each cell division brought new damage to DNA. Cells acquired almost all types of known chromosome and genome mutations, and amount of genetic aberration directly depended on cultivation time.

Are genetically unstable stem cells suitable for cell therapy? The majority of scientists are sure that changes in chromosomes can cause malignant transformation of a cell, however, there are very few unstable cells, and one should not be afraid to use cultivated stem cells for some sort of therapy. Russian scientists have another point of view – anomalous cells can have three ways of development: they can die, proliferate with the same speed as normal cells, or proliferate much faster than normal cells. Most probably, all three variants are possible. Since chromosome aberrations may cause malignant transformation, genetic stability of stem cells should be the first thing a doctor pays attention to before any kind of cell therapy.

Source: Russian Science News

Kizilova Anna