5-Azacytidine enhances proliferation in transplanted rat fetal epiglottis

Abstract

Fetal rat epiglottis and its developmental potential in ectopic transplants under the influence of the epigenetic drug was investigated. Epiglottises from 17-days-old rat embryos were transplanted under kidney capsules of adult rats for 14 days. 5-azacytidine (5 mg/kg) was injected intraperitoneally during first three days and controls were sham treated. TEM, immunohistochemical detection and quantitative stereological analysis of the Proliferating Cell Nuclear Antigen (PCNA) expression (numerical density N(v)) were performed. Typical chondroblasts with long surface processes and sparse lipid droplets were found in fetal epiglottis and chondrocytes with shorter processes, numerous lipid droplets and elastic fibers in adult. PCNA was expressed in almost all cells of the fetal epiglottis while in the adult it was expressed in minority of cells. In transplants, differentiation progressed towards the differentiation found in the adult. Application of 5-azacytidine increased the capacity for proliferation (N(v PCNA)) in comparison to controls but no difference in differentiation was observed. Data about the developmental potential and induction of proliferation in mammalian epiglottis by epigenetic modulation is of importance for regenerative medicine.

Epigenetic drug 5-azacytidine impairs proliferation of rat limb buds in an organotypic model-system in vitro

“…Although its immunohistochemistry levels in rat renewing tissues were found to be higher than those of other cell proliferation markers, those markers sometimes could not be visualized due to technical problems (21). In our current experiments, in the same way as in previously published studies (9,10,15), PCNA signal was always easily detected. The quantitative difference in its expression (Nv), found between experimental and control groups of limb buds, was in accordance with the results obtained by measurements of the overall explant growth.…”

“…However, during in vitro culture, vasculogenesis found in 13 days old isolated limb buds seems to have disappeared. The reason for this was probably the lack of specific in vivo signals, which are absent from the simple in vitro environment (15). …”

“…The signal was always present in the nuclei although the cytoplasmic signal together with the conspicuous nuclear staining was also found. Nuclei of the cells that were negative for PCNA were stained by the counterstain (blue) (9,10,15). Randomly selected paraffin blocks (6 for each group of explants – total 24 blocks) were used for stereological analysis of PCNA-positive cells.…”

“…Recent results associate the impact of 5azaC in an in vitro cell culture developmental model with a decrease in cell proliferation (14). On the other hand, in a cartilaginous organ transplanted in vivo it enhanced cell proliferation (15). This may seem to be controversial but 5azaC acted specifically for each developmental model system.…”

A Free Radical Scavenger Ameliorates Teratogenic Activity of a DNA Hypomethylating Hematological Therapeutic

“…In contrast to the negative 5azaC activity on cell proliferation in the limb bud as an immature whole organ, we showed that proliferation of the vertebral cartilage was increased by 5azaC, similarly as in 17-day-old fetal epiglottis of the same strain of rats transplanted in vivo [65]. The 5azaC-induced hypomethylation also reversed the aged phenotype of the adult mesenchymal stem cells by enhancing cell proliferation [59].…”