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Kinetics of chick embryo cell types in culture
Insights
Chick embryonic fibroblasts and chondroblasts exhibit similar cellular aging and population doubling limits. However, retinal pigment cells show a distinct doubling potential, indicating cell-type-specific aging.
Area of Science:
- Cell Biology
- Developmental Biology
- Aging Research
Background:
- Cellular senescence limits the proliferative capacity of normal cells.
- Understanding population doubling limits is crucial for cell culture and aging studies.
Purpose of the Study:
- To compare the growth kinetics and population doubling limits of different chick embryonic cell types.
- To investigate factors influencing cellular lifespan and aging in vitro.
Main Methods:
- Culturing chick embryonic fibroblasts, chondroblasts, and retinal pigment cells.
- Assessing cumulative population doubling levels (PDL) and cell cycle kinetics.
- Analyzing the effect of hydrocortisone and insulin on cell growth.
Main Results:
- Fibroblasts and chondroblasts had similar population doubling levels (42 +/- 2 PDL and 37 +/- 3 PDL, respectively).
- Retinal pigment cells displayed a lower doubling potential (29 +/- 1 PDL).
- Hydrocortisone and insulin shortened fibroblast lifespan but not that of retinal pigment cells.
Conclusions:
- Cell type influences population doubling limits during embryogenesis.
- Cellular aging involves an extended G1 phase, impacting population doubling time.
- Fibroblast aging potential is consistent across different embryonic ages.
Abstract:
The growth kinetics and population doubling limits of chick embryonic fibroblasts, chondroblasts, and retinal pigment cells were compared. Chondroblasts were found to have a cumulative population doubling level (37 +/- 3 PDL) similar (p = 0.05) to that of control fibroblasts (42 +/- 2 PDL), in individual and pooled clones. While both cell types have similar doubling potential, the proportion of tritium-labeled nuclei decreases, and differs significantly as doubling level increases. This age-associated decline is due to an extension in the population doubling time. Direct cell-cycle analysis shows this increase to occur in the G1 phase. Furthermore, cartilage colonies maintain their phenotypic expression (metachromasia) throughout their lifespan under conditions of subcloning at sparse density. When fibroblasts derived from 15 day chick embryos are compared with fibroblasts from 10 day embryos (41 +/- 2 PDL) there is no significant difference (p = 0.05) in cumulative PDL or percent labeled nuclei, indicating that fibroblasts of different embryonic age have similar potential. The addition of hydrocortisone and insulin to the medium significantly shortens (25 +/- 2 PDL) the lifespan of 10 day chick fibroblasts. Kinetics of retinal pigment cells show a population doubling potential (29 +/- 1 PDL) different from fibroblasts and chondroblasts, suggesting that different cell types may not have similar limits on doubling potential when first determined in embryogenesis. Hydrocortisone and insulin have no effect on the growth kinetics or lifespan of retinal pigment cells in culture.