Abstracts Biological Sciences

Analysis of the applicability of iPS cell-based approaches to bypass senescence and to re-establish rejuvenation features in human MSCs from aged individuals

by Matthias Megges

Ageing-related limits in the propagation and the application possibilities of primary human bone marrow-derived mesenchymal stem cells (hMSCs) can be circumvented by generating induced pluripotent stem cells (iPS cells) from them. iPS cells are able to self-renew without senescence and have potential as clinically relevant source of hMSC-like cells (iMSCs). Recent evidence suggests that donor cell type specific gene expression is retained in iPS cells, whereas ageing-related processes are most likely reverted to a younger state during pluripotency induction. Moreover, ambiguous results have been reported addressing the retention of ageing processes in iMSCs and other iPS derivatives. Therefore, the extent of the retention of ageing hallmarks in iPS cells and iMSCs from aged hMSCs needs more detailed clarification. To shed light on these aspects, ageing-related features and gene expression patterns were comparatively characterised in hMSCs of fetal femur isolated 53 days post-conception and in hMSCs of donors of 60-74 years before and after pluripotency induction and redifferentiation to iMSCs. Comparative viral and non-viral reprogramming of hMSCs with different age background suggested an age-related decline in reprogramming efficiency. iPS cells could be derived from fetal hMSCs with viral and non-viral methods and from an aged donor with non-viral methods with addition of vitamin c. iMSCs were derived from iPS cells of fetal and aged background. Cell type identity and according functionality could be confirmed in primary hMSCs, corresponding iPS cells and iMSCs irrespective of age. Further, comparison of ageing features and related gene expression patterns indicated age-related differences in senescence and oxidative stress-related processes in primary hMSCs. Upon pluripotency induction, these ageing-related differences were not detectable and most likely reverted to a more immature state. Moreover, the presence of oxidative DNA damage, response to oxidative stress was decreased in both age groups. Moreover, processes related to energy metabolism and glutathione metabolism were changed irrespective of age. Despite this, ageing-related processes seemed to be re-introduced in iMSCs. In particular, gene expression signatures annotated to senescence, oxidative stress response, ageing, insulin signalling, oxidative phosphorylation, glycolysis and cytoskeleton suggested reflection of donor age in iMSCs. However, glutathione metabolism and DNA damage repair-associated gene expression indicated a reversion to a more immature state. The results described herein suggest a reflection of donor age in iPS cells and iMSCs derived from hMSCs next to reversion of particular ageing aspects to a more fetal-like state in both cell types. Further exploration of these previously undescribed processes in hMSC-derived iPS cells and iMSCs will help to translate regenerative approaches of these cells tailored for elderly patients into clinical applications. Die Zellexpansion und Anwendbarkeit von primären humanen mesenchymalen…