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Long-term Growth of Finite Life Span Normal Human Epithelial Cells



  • Examine carcinogenesis, aging, expression of genes, proteins and miRNA, signaling pathways, epigenetics, and genomic stability
  • Develop quantitative assays for potentially pro or anti carcinogenic or aging agents, or toxic agents
  • Generate transformed HMEC lines


  • Enables the creation of large standardized batches of normal HMEC (60 PD)
  • Elucidates a model that appears to closely replicate in vivo carcinogenesis
  • May provide for easier generation of immortalized HMEC lines


Martha Stampfer and colleagues at Berkeley Lab have developed a system for consistently achieving as many as 60 population doublings (PD) in a cell culture of finite lifespan human mammary epithelial cells (HMEC).   Previous methods developed by Stampfer and currently distributed commercially achieve nearly equivalent PD, but these cell types (post-selection) have already overcome one of the barriers to immortality and contain properties not representative of cells most prevalent in normal human breast.   Conventional culturing methods used in most laboratories for normal HMEC typically yield 30 PD of active growth at best.

Berkeley Lab's recent success in culturing cells is the result of a data-supported model of the proliferation barriers encountered by HMEC that offers new perspectives on malignant progression. The paradigm, developed by Stampfer's team, predicts that HMEC encounter two mechanistically distinct proliferation barriers. The first, stasis, is a consequence of various stresses and appears to be telomere length independent. The second is an extremely stringent barrier imposed by critically shortened telomeres, producing telomere dysfunction and genomic instability. This characterization of proliferation barriers and senescence encountered by cultured HMEC is consistent with in vivo studies of human carcinoma progression.

Based on this model, the Berkeley Lab researchers developed a medium consisting of a ratio of two previously developed media that increases the culturing of pre-stasis HMEC to approximately 45 PD. The addition of an anti-stress growth factor to the medium in primary or secondary passage aids the cells in postponing the onset of the stress barrier and can increase the PD to approximately 60.

Besides enabling the generation of large standardized HMEC batches and related assays, the Berkeley Lab media and method may also provide for easier generation of transformed HMEC lines from pre-stasis HMEC populations rather than through the commercially available post-selection HMEC that have already overcome the stasis barrier.



  • Published PCT Patent Application WO/2007/115223 available at Published US Patent Application 2010-0022000 available here or at Available for licensing or collaborative research.



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