Methods of karyoplast cell cycle synchronization for increasing the efficiency of somatic cloning of farm animals

Abstract

This article is aimed to the analysis of methods for synchronizing the cell cycle of the somatic cells (karyoplasts) upon somatic cloning of farm animals. To obtain cloned animals, the oocytes at the metaphase of the second meiotic division without prior activation are applied as recipient cells in most experiments. In most experiments to obtain cloned offspring, oocytes are used as recipient cells at metaphase of the second meiotic division without prior activation, which determines the choice of somatic cells as karyoplasts at the G0/G1 stage, the most optimal for subsequent nuclear reprogramming by oocyte cytoplasmic factors. The most commonly used methods for arresting cells in this phase are serum starvation and/or contact inhibition, which allows up to 90% of cells to be stopped at the G0/G1 stage. However, despite the effectiveness of these methods, they have a number of significant limitations, and therefore the addition of components to the culture medium of somatic cells that prevent the progression of cells through the cell cycle stages is becoming widespread. The advantage of using chemical inhibitors is the ability of a number of them to have a protective effect on somatic cells, preventing the induction of apoptotic changes. The efficacy of butyrolactone-I, mimosine and aphidicolin application is controversial but a number of studies attests the possible using of these drugs to synchronize the karyoplasts. Thus, there is a wide range of methods for effective synchronization of the cell cycle of karyoplasts, and when choosing the optimal method, one should pay attention to the type of cells, the species of animals from which they were obtained, the permissible duration of cultivation under given conditions in order to minimize the negative impact of conditions on karyoplast viability.