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#cell lines

2 public questions tagged with this topic.

Animal Tissue Culture 3

MRC-5 cells are derived from:

Death phase also called decline phase is final segment of in vitro growth curve where net cell number decreases as death rate surpasses division rate. Triggered by exhaustion of essential nutrients glucose and L-glutamine, severe acidification due to lactic acid production, accumulation of toxic ammonium from glutaminolysis, oxidative stress from reactive oxygen species generated by mitochondrial dysfunction, and activation of intrinsic apoptosis pathway involving Bax translocation, cytochrome c release from mitochondria, apoptosome formation with Apaf-1, and executioner caspase-3 cleavage of PARP. Senescent cells also accumulate expressing beta-galactosidase and senescence-associated secretory phenotype factors IL-6, IL-8, MMPs. Morphologically cells round up, detach, display membrane blebbing, chromatin condensation, and release cellular contents increasing debris. Debris promotes further damage via released proteases and DNases. In laboratory practice, allowing cultures to proceed into death phase compromises experimental results, selects for resistant subpopulations, and causes loss of valuable lines, underscoring importance of regular feeding and subculture before plateau extends.

Ref: Freshney Ch.13 Death phase decline apoptosis; Elmore S Toxicol Pathol 2007 Apoptosis intrinsic pathway caspase activation.

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Animal Tissue Culture 1

Transformed cell lines usually:

Transformation to continuous cell line involves acquisition of genetic alterations bypassing normal senescence checkpoints that restrict primary cells. Spontaneous immortalization occurs rarely at frequency ten to minus seventh in rodent cells due to p53 mutation combined with telomerase reactivation via hTERT promoter mutation -124 C>T creating ETS binding site, viral oncogene mediated transformation using SV40 large T antigen binding and inactivating p53 tumor suppressor and retinoblastoma Rb releasing E2F transcription factors, human papillomavirus E6 binding p53 promoting degradation via ubiquitin ligase E6AP and E7 binding Rb, adenovirus E1A E1B similar, chemical carcinogen methylcholanthrene introducing activating Ras G12V mutation locked GTP bound constitutively activating Raf-MEK-ERK, or ectopic expression hTERT alone extends lifespan but often insufficient without additional oncogenes. This mechanistic insight supports diagnostic and therapeutic applications while reinforcing core immunological and cell biology principles taught in advanced curricula. This mechanistic detail underpins practical applications in diagnostics, vaccine design, and biopharmaceutical manufacturing.

Ref: Alberts MBoC transformation immortalization SV40 p53 Ras telomerase; Freshney transformed lines serum mitogens PDGF MAPK AKT dependence.

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