A recently published research study led by a group at the University of California at San Diego (UCSD) has found that putting stem cells into culture, both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), leads to the generation of abnormalities in the DNA of these cells. This research, published in the Jan. 7, 2011, edition of the journal Cell Stem Cell, indicates that specific regions of the chromosomes of these cells are susceptible to structural changes once these cells have been put into culture to grow. Interestingly, ESCs and iPSCs showed different specific alterations in the structure of their DNA.
Generally speaking, when stem cells are isolated from tissues or blood, the absolute number of them is relatively small. In order to be useful clinically, the population of stem cells must be expanded by growing them in specialized broths in dishes in a very controlled, sterile environment.
As questions regarding the overall utility of these different cells for use in the clinical setting have grown, this study magnifies the importance of critical surveillance of cultured stem cell populations to be certain that they did not change significantly while being in culture. As stated by the authors of this study in the Cell Stem Cell article:
“Our results illustrate the dynamic nature of genomic abnormalities in pluripotent stem cells and the need for frequent genomic monitoring to assure phenotypic stability and clinical safety.”
In a press release issued by the UCSD news office, Dr. Jeanne Loring, senior author of the study and Director of the Center for Regenerative Medicine at the Scripps Research Institute, said:
“Since genetic aberrations are often associated with cancers, it is vital that cell lines destined for clinical use are free from cancer-associated genomic alterations.”
This study now underlines the importance of better understanding how stem cells behave, and potentially change, once they have been placed into culture vessels.
Over the last several years, there has been a steady expansion in the number of studies arguing for the utility and potential clinical usefulness of stem cells for treating a range of human disorders. Indeed, stem cells have already been used in experimental settings to treat selected human medical conditions and there has been some degree of success. As studies move forward, and more potential stem cell treatments are tried, it will be critically important to fully characterize the population of cultured stem cells prior to their administration to patients.
Reference: Laurent LC, Ulitsky I, Slavin I, Tran H, et al. Dynamic Changes in the Copy Number of Pluripotency and Cell Proliferation Genes in Human ESCs and iPSCs during Reprogramming and Time in Culture. Cell Stem Cell, 8(1):106-118; 7 Jan 2011.