The Protein Man's Blog | A Discussion of Protein Research

By Ellyn Daugherty, Biotechnology: Science for the New Millennium, 2E

What is Cell Freezing?

Cryopreservation, or cell freezing, is a crucial step of animal cell culture and long-term maintenance, which is different from the process of preserving bacteria and fungi. It is the most effective method of animal cell culture preservation and is accomplished by either a suitable cryogenic agent or liquid nitrogen. It can oftentimes be difficult to maintain cell lines, due to the viability of preserved cell lines, slow growth rates, physiological conditions, cell density and the type of cryoprotectant and freezing technique.

In eukaryotic cells, RNA processing occurs in the nucleus and the functional mRNA is transported to the cytoplasm. As soon as the mRNA transcript is synthesized from RNA polymerase II, RNA binding proteins (RBPs) attach to the mRNA transcript to prevent it from degradation during processing and exporting it from the nucleus. RBPs play an important role in RNA stability, maturation, transport, and localization. This process results in the formation of stable mature mRNA (lasts for several hours) than that in prokaryotes (5 seconds). 

Patient-derived xenografts (PDX) are arguably the most faithful and the most powerful modeling system in oncology today. And while PDX models are far from being perfect, most researchers find them extremely useful in studying cancer biology, biomarker development, drug discovery, and drug response. To date, no other system can provide a more accurate representation of human cancer than a PDX model can.