Purification of adipose stem cells – Mesenchymal stem cells (MSCs) have received attention in recent years due to their potential interest as replacement cells in regenerative medicine. An abundant and easily accessible source of adult MSCs are stem cells harvested from liposuction material. We purify adipose tissue stem cells (ASCs) with 99% purity from the stromal vascular fraction of human liposuction material. Ten to 20 million ASCs can be purified from 300 ml liposuction material (Boquest et al., 2006). Our ASC purification protocol can be found here. Like bone marrow MSCs, ASCs can give rise to a variety of cell types; however, they have a propensity to differentiate into mesodermal lineages (Boquest et al., 2005).MSCs can be expanded in culture for 15-40 population doublings, period during which subpopulations of cells can undergo localized changes in DNA copy number (shown by comparative genomic hybridization) and changes in DNA methylation patterns (Meza-Zepeda et al., 2007; Dahl et al., 2008). Interestingly, bone marrow MSCs seem to me more prone to genetic alterations than adipose stem cells.
Epigenetic makeup of MSCs – Even so, the capacity of ASCs to differentiate into non-adipogenic pathways seems to be restricted. DNA methylation analyses of lineage-specific promoters in ASCs suggests an epigenetic programming of these cells for adipogenesis, preferentially over other lineages (Noer et al., 2006; Noer et al., 2007; Boquest et al., 2007). We are investigating histone modification profiles of ASCs by chromatin immunoprecipitation (ChIP) (Noer et al., 2008). We are also initiating the genome-wide profile of promoter DNa methylation profiling in MSCs from various tissues to determine the extent to which these are epigenetically programmed for specific lineages.
Persons involved: Dr. Agate Noer, Anita Sørensen, Kristin Vekterud, Ingrid Andersen
Collaborators: Dr. Jan Brinchann (Rikshospital, Oslo), Dr. Leonardo Meza-Zepeda (Radium Hospital, Oslo), Dr. Ola Myklebost (Radium Hospital, Oslo).
Chromatin organization in MSCs – Pluripotency is enabled by specific combinations of histone modifications and DNA methylation patterns in stem cells, which provide a potential for gene activation. Using array-based and imaging techniques, we are investigating the epigenomic organization of MSCs.
Persons involved: Dr. Erwan Delbarre, Dr. Thomas Küntziger, Bente-Marie Jacobsen, Andy Reiner
