Background
With the development of biomedical research tools, the pressure and demand for stable cell lines has triggered a variety of methods to produce stable, well-characterized cells. Many studies particularly rely on stable cell lines for drug screening and toxicology studies. The practicality of embryonic stem cells and induced pluripotent stem cells has caused some powerful debates because a large number of cells can be produced. If the latter is the case, the specific properties of the patient or disease to be studied can be consistent with the target cells. In terms of reliable differentiation, there are also some limitations. For this purpose, the use of primary cell production cell lines that are more advanced than the early embryonic development stage.
The Application of Conditional Cell Immortalization
Conditional immortality uses inducible transgene technology to create a cell that can be expanded in a consistent manner when the transgene is active. If the transgene is permanently activated, then in theory the cell will divide continuously. However, for conditional immortalization technology, it is essential that the transgene is controllable. Therefore, when the required clinical quantity of cell material is reached, the transgene can be inactivated by the operator, allowing the cells to return to normal after mitosis status. This ensures that the cell preparation delivered to the patient is safe and has a negligible risk of cancer, overcoming the main concern for composing immortal cells; if there are cancer-causing mutations, cells with immortal proliferation potential may become cancerous.
Normal human somatic cells undergo limited cell division before entering a limited state of division. This natural process is the inherent anti-tumor mechanism. Certain cells (such as fibroblasts) can undergo 50-60 times population doubling before senescence, while other cells (such as mammary luminal epithelial cells (the cell type of origin for most breast cancers)) only undergo a few times in culture Split. This natural process and the change in replication lifespan between different cell types limit the generation of new cell lines through simple culture of normal cells, especially if the business plan is to deliver industrial quantities of allogeneic cell products. In fact, early cell lines developed for research purposes are only obtained from tumors that are easy to grow in culture.
Cell Immortalization is a complicated process because not all cells can be immortalized using a single genetic tool. In addition, simply immortalizing cells will produce a large number of cells for drug screening, but due to the lack of cell cycle control and the inability to turn off the genetic modification that drives cell division, this cell material will not be suitable for implantation in patients.
The emerging cell and gene therapy industry will become more powerful through the use of new and powerful molecular tools that can create conditionally immortal therapeutic cell lines from adult cells that have the potential to cure or regenerate in their natural state, but it cannot be extended to maintain high yields in this natural state. Cell immortalization itself brings concerns about genetic instability and transformation into cancer phenotypes. Conditional steps overcome this problem by using a fully controllable mechanism that removes or permanently silences immortalizing genes before delivery.
There are many different molecular biology tools that can be used to create operably controlled conditional immortal cells by manipulating reagents and environments, which provides a potential solution for industrial-scale patient cell generation. Obviously, it has commercial value in creating conditional immortalized cell lines for treatment. For other technologies, there are some challenges that need to be resolved, such as ensuring that the transgene is completely silenced before delivering the cells to the patient.
