|DNA Markers Point Toward Tissue Regeneration Strategies|
|SciMed - Biology|
|TS-Si News Service|
|Monday, 19 March 2012 14:00|
Boston, MA, USA. Researchers have identified epigenetic signatures, DNA markers that control transient changes in gene expression, within reprogrammed skin cells.
Understanding the controls for expression of the protein is a step closer to developing personalized tissue regeneration strategies using stem cells from a patient.
These signatures can predict the expression of a wound-healing protein in reprogrammed skin cells or induced pluripotent stem cells (iPSCs), cells that take on embryonic stem cell properties. When skin cells are reprogrammed, many of their cellular properties are recalibrated as they aquire stem cell properties and then are induced to become skin cells again. In order for these induced stem cells to be viable in treatment for humans (e.g., tissue regeneration and personalized wound healing therapies), researchers need to understand how they retain or even improve their characteristics after they are reprogrammed. The findings appear in the Journal of Cell Science.
Since the initial discovery of cell reprogramming, scientists have struggled with the unpredictability of the cells due to the many changes that occur during the reprogramming process.
Classifying specific epigenetic signatures, as this study did, allows researchers to anticipate ways to produce cell types with optimal properties for tissue repair while minimizing unintended cellular abnormalities.The researchers used reprogrammed cells to generate three-dimensional connective tissue that mimics an in vivo wound repair environment. To verify the role of the protein (PDGFRbeta) in tissue regeneration and maintenance, the team blocked its cellular expression, which impaired the cells' ability to build tissue.
"We determined that successful tissue generation is associated with the expression of PDGFRbeta. Theoretically, by identifying the epigenetic signatures that indicate its expression, we can determine the reprogrammed cells' potential for maintaining normal cellular characteristics throughout development," said first author Kyle Hewitt, PhD, a graduate of the cell, molecular & developmental biology program at the Sackler School of Graduate Biomedical Sciences, and postdoctoral associate in the Garlick laboratory at the Tufts University School of Dental Medicine (TUSDM).
"The ability to generate patient-specific cells from the reprogrammed skin cells may allow for improved, individualized, cell-based therapies for wound healing. Potentially, these reprogrammed cells could be used as a tool for drug development, modeling of disease, and transplantation medicine without the ethical issues associated with embryonic stem cells," said senior author Jonathan Garlick, DDS, PhD.
Garlick is a professor in the department of oral and maxillofacial pathology, and director of the division of tissue engineering and cancer biology at TUSDM. He also is a member of the cell, molecular & developmental biology program faculty at the Sackler School and the director of the Center for Integrated Tissue Engineering (CITE) at TUSDM.
FundingThis work was supported by a grant to Dr. Garlick from the National Institute for Dental and Craniofacial Research (NIDCR), part of the National Institutes of Health (NIH).
ParticipationAdditional authors of the study are Yulia Shamis, MSc, a PhD candidate in the cell, molecular, and developmental biology program at the Sackler School; Elana Knight, BSc, and Avi Smith, BA, both research technicians in the Garlick laboratory; Anna Maione, a PhD student in the cell, molecular & developmental biology program at the Sackler School, and Addy Alt-Holland, PhD, MSc, assistant professor at the Tufts University School of Dental Medicine (TUSDM).
CitationPDGFRbeta Expression and Function in Fibroblasts Derived from Pluripotent Cells is Linked to DNA Demethylation. Kyle J. Hewitt, Yulia Shamis, Elana Knight, Avi Smith, Anna Maione, Addy Alt-Holland, Steven D. Sheridan, Stephen J. Haggarty, Jonathan A. Garlick. Journal of Cell Science. doi:10.1242/?jcs.099192
Platelet-derived growth factor receptor-beta (PDGFRß) is required for the development of mesenchymal cell types, and plays a diverse role in the function of fibroblasts in tissue homeostasis and regeneration. In this study, we characterized the expression of PDGFRß in fibroblasts derived from human embryonic stem cells and induced pluripotent stem cells, and showed that this expression is important for cellular functions including migration and extracellular matrix production and assembly in 3D self-assembled tissues. To determine potential regulatory regions predictive of expression of PDGFRß following differentiation from ESC and iPSC, we analyzed the DNA methylation status of a region of the PDGFRß promoter containing multiple CpG sites before and after differentiation. We demonstrated that this promoter region is extensively demethylated following differentiation, and represents a developmentally-regulated, differentially-methylated region linked to PDGFRß expression. Understanding the epigenetic regulation of genes such as PDGFRß, and identifying sites of active DNA demethylation, is essential for future applications of pluripotent stem cell-derived fibroblasts for regenerative medicine.
|Last Updated on Monday, 19 March 2012 09:06|