Cell Immortalization: In Vivo Molecular Bases and In Vitro Techniques for Obtention

Abstract

Somatic human cells can divide a finite number of times, a phenomenon known as the Hayflick limit. It is based on the progressive erosion of the telomeric ends each time the cell completes a replicative cycle. Given this problem, researchers need cell lines that do not enter the senescence phase after a certain number of divisions. In this way, more lasting studies can be carried out over time and avoid the tedious work involved in performing cell passes to fresh media. However, some cells have a high replicative potential, such as embryonic stem cells and cancer cells. To accomplish this, these cells express the enzyme telomerase or activate the mechanisms of alternative telomere elongation, which favors the maintenance of the length of their stable telomeres. Researchers have been able to develop cell immortalization technology by studying the cellular and molecular bases of both mechanisms and the genes involved in the control of the cell cycle. Through it, cells with infinite replicative capacity are obtained. To obtain them, viral oncogenes/oncoproteins, myc genes, ectopic expression of telomerase, and the manipulation of genes that regulate the cell cycle, such as p53 and Rb, have been used.

Cell Immortality: In Vitro Effective Techniques to Achieve and Investigate Its Applications and Challenges

“…By following this approach, cells can surpass the Hayflick limit and evade the mechanisms linked to replicative senescence and eventual cell apoptosis. This is achieved through the upregulation of various viral oncogenes/oncoproteins, the TERT component of telomerase, and the expression of genes that regulate the cell cycle, ultimately leading to conditional immortality [ 61 ]. In addition, the use of immortal cell lines has been helpful in many researches, some of which were mentioned in this article, and these cases can present a sign of the importance of creating a cell line through the immortalization technique.…”

“…The immortality conferred by viral oncoproteins is intricately linked to the deactivation of cell cycle-regulating proteins (such as p16, p14, p21, p53, and Rb). Through this pathway, viral oncoproteins can induce the deactivation of tumor suppression mechanisms and may even trigger the expression of telomerase [ 61 ].…”

“…The expression of c-Myc is predominantly observed in actively proliferating cells, whereas N-Myc and L-Myc play roles in differentiation processes. Among these oncogenes, the c-Myc gene has been the subject of the most extensive studies [ 61 ]. It is worth noting that there is an association between p53 and c-Myc, as the Myc signaling pathway governs both apoptosis and cell immortalization, with the latter being contingent on the status of p53 [ 92 ].…”

“…As mentioned, the risk of oncogenic integration into chromosomes still raises various safety concerns when using an oncogenic transferable agent in host cells [ 61 ]. Using hTERT as a means of achieving immortalization through less phenotypic/karyotypic alterations has been proposed [ 60 ].…”

Investigation of the In Vitro Immunomodulatory Effects of Extracts from Green-Lipped Mussels (Perna canaliculus)

“…Typically, peripheral blood mononuclear cells (PBMCs) are used to evaluate immune cell functions in metabolic disorders [49]. However, there are limitations associated with the utilization of human stem cells, such as ethical concerns with PBMCs [50]. The most significant factors that affect the use of PBMCs are accessibility to the material and higher inherent variability across donors.…”