Published online Oct 26, 2019. doi: 10.4252/wjsc.v11.i10.787
Peer-review started: February 20, 2019
First decision: April 16, 2019
Revised: May 3, 2019
Accepted: September 4, 2019
Article in press: September 5, 2019
Published online: October 26, 2019
Tissue engineering has yet to reach its ideal goal, i.e. creating profitable off-the-shelf tissues and organs, designing scaffolds and three-dimensional tissue architectures that can maintain the blood supply, proper biomaterial selection, and identifying the most efficient cell source for use in cell therapy and tissue engineering. These are still the major challenges in this field. Regarding the identification of the most appropriate cell source, aging as a factor that affects both somatic and stem cells and limits their function and applications is a preventable and, at least to some extents, a reversible phenomenon. Here, we reviewed different stem cell types, namely embryonic stem cells, adult stem cells, induced pluripotent stem cells, and genetically modified stem cells, as well as their sources, i.e. autologous, allogeneic, and xenogeneic sources. Afterward, we approached aging by discussing the functional decline of aged stem cells and different intrinsic and extrinsic factors that are involved in stem cell aging including replicative senescence and Hayflick limit, autophagy, epigenetic changes, miRNAs, mTOR and AMPK pathways, and the role of mitochondria in stem cell senescence. Finally, various interventions for rejuvenation and geroprotection of stem cells are discussed. These interventions can be applied in cell therapy and tissue engineering methods to conquer aging as a limiting factor, both in original cell source and in the in vitro proliferated cells.
Core tip: To attain profitable off-the-shelf tissues and organs, we must deal with the challenge of identifying and isolating an optimal cell source. Different types of stem cells with different properties have been used in tissue engineering and cell therapy to face this challenge. Although aging is an inevitable process that can eventually limit the function and stemness of stem cells, it is a conquerable phenomenon. In this article, we have reviewed several applicable interventions that can be used to overcome cellular aging.