Chromosome 7 and 19 Trisomy in Cultured Human Neural Progenitor CellsReportar como inadecuado




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Background

Stem cell expansion and differentiation is the foundation of emerging cell therapy technologies. The potential applications of human neural progenitor cells hNPCs are wide ranging, but a normal cytogenetic profile is important to avoid the risk of tumor formation in clinical trials. FDA approved clinical trials are being planned and conducted for hNPC transplantation into the brain or spinal cord for various neurodegenerative disorders. Although human embryonic stem cells hESCs are known to show recurrent chromosomal abnormalities involving 12 and 17, no studies have revealed chromosomal abnormalities in cultured hNPCs. Therefore, we investigated frequently occurring chromosomal abnormalities in 21 independent fetal-derived hNPC lines and the possible mechanisms triggering such aberrations.

Methods and Findings

While most hNPC lines were karyotypically normal, G-band karyotyping and fluorescent in situ hybridization FISH analyses revealed the emergence of trisomy 7 hNPC+7 and trisomy 19 hNPC+19, in 24% and 5% of the lines, respectively. Once detected, subsequent passaging revealed emerging dominance of trisomy hNPCs. DNA microarray and immunoblotting analyses demonstrate epidermal growth factor receptor EGFR overexpression in hNPC+7 and hNPC+19 cells. We observed greater levels of telomerase hTERT, increased proliferation Ki67, survival TUNEL, and neurogenesis βIII-tubulin in hNPC+7 and hNPC+19, using respective immunocytochemical markers. However, the trisomy lines underwent replicative senescence after 50–60 population doublings and never showed neoplastic changes. Although hNPC+7 and hNPC+19 survived better after xenotransplantation into the rat striatum, they did not form malignant tumors. Finally, EGF deprivation triggered a selection of trisomy 7 cells in a diploid hNPC line.

Conclusions

We report that hNPCs are susceptible to accumulation of chromosome 7 and 19 trisomy in long-term cell culture. These results suggest that micro-environmental cues are powerful factors in the selection of specific hNPC aneuploidies, with trisomy of chromosome 7 being the most common. Given that a number of stem cell based clinical trials are being conducted or planned in USA and a recent report in PLoS Medicine showing the dangers of grafting an inordinate number of cells, these data substantiate the need for careful cytogenetic evaluation of hNPCs fetal or hESC-derived before their use in clinical or basic science applications.



Autor: Dhruv Sareen, Erin McMillan, Allison D. Ebert, Brandon C. Shelley, Julie A. Johnson, Lorraine F. Meisner, Clive N. Svendsen

Fuente: http://plos.srce.hr/



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