PDGF-AB and 5-Azacytidine induce conversion of somatic cells into tissue-regenerative multipotent stem cells

Abstract

Current approaches in tissue engineering are geared toward generating tissue-specific stem cells. Given the complexity and heterogeneity of tissues, this approach has its limitations. An alternate approach is to induce terminally differentiated cells to dedifferentiate into multipotent proliferative cells with the capacity to regenerate all components of a damaged tissue, a phenomenon used by salamanders to regenerate limbs. 5-Azacytidine (AZA) is a nucleoside analog that is used to treat preleukemic and leukemic blood disorders. AZA is also known to induce cell plasticity. We hypothesized that AZA-induced cell plasticity occurs via a transient multipotent cell state and that concomitant exposure to a receptive growth factor might result in the expansion of a plastic and proliferative population of cells. To this end, we treated lineage-committed cells with AZA and screened a number of different growth factors with known activity in mesenchyme-derived tissues. Here, we report that transient treatment with AZA in combination with platelet-derived growth factor–AB converts primary somatic cells into tissue-regenerative multipotent stem (iMS) cells. iMS cells possess a distinct transcriptome, are immunosuppressive, and demonstrate long-term self-renewal, serial clonogenicity, and multigerm layer differentiation potential. Importantly, unlike mesenchymal stem cells, iMS cells contribute directly to in vivo tissue regeneration in a context-dependent manner and, unlike embryonic or pluripotent stem cells, do not form teratomas. Taken together, this vector-free method of generating iMS cells from primary terminally differentiated cells has significant scope for application in tissue regeneration.

Intrinsic and extrinsic factors that influence ovarian environment and efficiency of reproduction in cattle

“…Furthermore, recent works carried out in other laboratories demonstrated the possibility to convert human skin fibroblasts into neural progenitor-like cells (Mirakhori et al, 2015) and mature bone and fat cells into tissue-regenerative multipotent stem (iMS) cells (Chandrakanthan et al, 2016) through the use of the demethylating agent 5-aza-CR, proving to be in agreement with our results. In addition, Cheng et al reported that, using a cocktail containing inhibitors of histone deacetylation, glycogen synthase kinase and TGF-β pathway, it is possible to convert human and murine fibroblasts into proliferating chemical-induced neural progenitor cells (ciNPC), under physiological hypoxic conditions (5% O2; Cheng et al, 2015).…”

Mountain high and valley deep: epigenetic controls of pluripotency and cell fate

“…They confirmed that specific chemical compounds can push cells to a transient less committed state, increasing cell plasticity for a relative short time-window, but sufficient to re-address an adult mature cell into another differentiated cell type (Harris et al, 2011;Pennarossa et al, 2013Pennarossa et al, , 2014Brevini et al, 2014;Mirakhori et al, 2015;Chandrakanthan et al, 2016).…”

The quest for an effective and safe personalized cell therapy using epigenetic tools

“…More recent experiments demonstrated that a brief exposure to a demethylating agent can push cells to a less committed state, increasing their plasticity for a short window of time sufficient to re-address cells towards a different cell type [2–7]. The starting hypothesis was that the processes associated with differentiation are driven by several mechanisms.…”

“…Among these, DNA methylation plays a fundamental role during both early embryonic development and cell lineage specification, causing silencing of large fraction of the genome and subsequent expression of gene essential for the maintenance of the differentiated and tissue-specific phenotype. Based on this, 5-azacytidine (5-aza-CR), a well-characterized DNMT inhibitor, was selected in order to remove the epigenetic “blocks” that are responsible for tissue specification [3–5, 7]. This drug is a chemical analog of cytosine, it can be incorporated into DNA and RNA, causing an increased effect in resting as well as in dividing cells, and it is known to be a direct inhibitor of methylation in newly synthesized DNA by blocking DNMT function [56].…”

“…This new approach demonstrated that it is possible to dynamically interact with cell genotype and phenotype through the use of epigenetic modifiers [2–7]. …”