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The effect of cyclosporin A on the proliferating chick embryo erythroblasts
M Peterka1, Z Likovský, R Peterková
1Institute of Experimental Medicine, Academy of Sciences, Czech Republic, Prague.
Insights
Cyclosporin A significantly altered chick embryo erythroblast proportions, impacting early blood development. Proerythroblast percentage in yolk sacs may indicate toxic damage in avian embryos.
Area of Science:
- Developmental Biology
- Toxicology
- Hematopoiesis
Background:
- Erythropoiesis, the production of red blood cells, begins early in avian embryonic development.
- The yolk sac blood islands are a primary site for embryonic erythropoiesis.
- Understanding normal erythropoiesis is crucial for assessing developmental toxicity.
Purpose of the Study:
- To quantify the proportion of proliferating erythroblasts during chick embryonic development (days 2-10).
- To investigate the effects of Cyclosporin A (CsA) on erythroblast populations in the embryonic yolk sac.
- To evaluate the potential of proerythroblast percentage as a biomarker for embryonic toxicity.
Main Methods:
- Counting proerythroblasts, basophilic erythroblasts, and polychromatophilic erythroblasts in chick embryo yolk sac blood islands from embryonic day 2 to 10.
- Administering intra-amniotic injections of Cyclosporin A (1.5 or 15.0 µg/embryo) on day 5.
- Analyzing changes in the proportion of proliferating erythroblasts post-injection.
Main Results:
- A decrease in less mature erythroid cells was observed from day 2 onwards, indicating the progression of erythropoiesis.
- Cyclosporin A injection caused significant alterations in the proportion of proliferating erythroblasts.
- Observed changes suggest initial release of mature cells and a subsequent dose-dependent decrease in stem cells.
Conclusions:
- The proportion of proliferating erythroblasts in chick embryo yolk sac blood islands changes throughout development.
- Cyclosporin A exposure disrupts normal embryonic erythropoiesis.
- The percentage of proerythroblasts may serve as a sensitive indicator of toxic effects on late-stage avian embryos.
Abstract:
The proportion of proliferating erythroblasts, i.e. proerythroblasts, basophilic erythroblasts and polychromatophilic erythroblasts in blood islands of the chick embryo yolk sac, were counted during embryonic days 2-10. From day 2 when high amounts of erythroblasts signalized the onset of embryonic erythropoiesis, the percentage of less mature erythroid cells gradually decreased. Intraamniotic injection of cyclosporin A in doses 1.5 or 15.0 micrograms per embryo on day 5 led to significant changes in the proportion of proliferating erythroblasts in the yolk sac blood islands. We speculate that these changes were caused initially by the release of the more mature cells into the circulation and later by a dose-dependent decrease in the number of stem cells. The estimation of proerythroblast percentage from all proliferating erythroblasts in the yolk sac blood islands may serve as a valuable indication of toxic damage in the late avian embryo.