engleski

5-azacytidine impairs mammalian limb bud development ex vivo

The epigenetic therapeutic DNA demethylating agent 5-azacytidine (Vidaza) has been approved for treatment of the myelodysplastic syndrome in all 5 FAB forms. We have been investigating its influence on the developmental potential of rat limb buds in an organ culture system ex vivo. Fisher rat fore- and hind-limb buds were removed under the dissecting microscope from 13- and 14-day-old embryos and placed on a lens paper supported by a stainless steel grid, where they spent three days or two weeks at the air-liquid interface. Eagle's MEM was supplemented with 50% rat serum and used alone or with 5 μm 5-azacytidine. Two limb bud axes were measured. Samples were processed by routine histology and uninterrupted serial sections were stained by HE, Masson trichrome or Azan stain. PCNA expression was immunohistochemically assessed and strereologically quantified. In isolated limb buds, immature epithelium, mesenchyma, myotubes and different stages of angiogenesis such as single hemangioblasts, hemangioblast aggregates, blood islands and capillaries filled with erythroblasts were present. During the 3-day culture period, stratified epithelium and cartilage differentiated, but differentiated striated muscle was not observed. In limb buds that spent two weeks in culture, necrosis and absence of angiogenesis together with keratinization of the stratified epithelium were discovered. Limb buds treated with 5-azacytidine were smaller than controls and numerical density of PCNA expression was lower. It is concluded that developmental parameters which can be assessed in this mammalian ex vivo model system make it appropriate to screen for embryotoxic and teratogenic substances such as the epigenetic drug 5-azacytidine used in this study.

Limb bud ; in vitro culture ; rat ; 5-azacytidine

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