Preliminary Evidence for the Dedifferentiation of RAW 264.7 Cells into Mesenchymal Progenitor-Like Cells by a Purine Analog

In Vitro Characterization of Reversine-Treated Gingival Fibroblasts and Their Safety Evaluation after In Vivo Transplantation

Reversine is a purine derivative that has been investigated with regard to its biological effects, such as its anticancer properties and, mostly, its ability to induce the dedifferentiation of adult cells, increasing their plasticity. The obtained dedifferentiated cells have a high potential for use in regenerative procedures, such as regenerative dentistry (RD). Instead of replacing the lost or damaged oral tissues with synthetic materials, RD uses stem cells combined with matrices and an appropriate microenvironment to achieve tissue regeneration. However, the currently available stem cell sources present limitations, thus restricting the potential of RD. Based on this problem, new sources of stem cells are fundamental. This work aims to characterize mouse gingival fibroblasts (GFs) after dedifferentiation with reversine. Different administration protocols were tested, and the cells obtained were evaluated regarding their cell metabolism, protein and DNA contents, cell cycle changes, morphology, cell death, genotoxicity, and acquisition of stem cell characteristics. Additionally, their teratoma potential was evaluated after in vivo transplantation. Reversine caused toxicity at higher concentrations, with decreased cell metabolic activity and protein content. The cells obtained displayed polyploidy, a cycle arrest in the G2/M phase, and showed an enlarged size. Additionally, apoptosis and genotoxicity were found at higher reversine concentrations. A subpopulation of the GFs possessed stem properties, as supported by the increased expression of CD90, CD105, and TERT, the existence of a CD106+ population, and their trilineage differentiation capacity. The dedifferentiated cells did not induce teratoma formation. The extensive characterization performed shows that significant functional, morphological, and genetic changes occur during the dedifferentiation process. The dedifferentiated cells have some stem-like characteristics, which are of interest for RD.

Multiple functions of reversine on the biological characteristics of sheep fibroblasts

Previous reports have demonstrated that Reversine can reverse differentiation of lineage-committed cells to mesenchymal stem cells and suppress tumors growth. However, the molecular mechanisms of antitumor activity and promoting cellular dedifferentiation for reversine have not yet been clearly elucidated. In the present study, it was demonstrated that reversine of 5 μM could induce multinucleated cells through cytokinesis failure rather than just arrested in G2 or M phase. Moreover, reversine reversed the differentiation of sheep fibroblasts into MSC-like style, and notably increased the expression of pluripotent marker genes Oct4 and MSCs-related surface antigens. The fibroblasts treated with reversine could transdifferentiate into all three germ layers cells in vitro. Most importantly, the induced β-like cells and hepatocytes had similar metabolic functions with normal cells in vivo. In addition, reversine promoted fibroblasts autophagy, ROS accumulation, mitochondrial dysfunction and cell apoptosis via the mitochondria mediated intrinsic pathway. The results of high-throughput RNA sequencing showed that most differentially expressed genes (DEGs) involved in Mismatch repair, Nucleotide excision repair and Base excision repair were significantly up-regulated in reversine treated fibroblasts, which means that high concentration of reversine will cause DNA damage and activate the DNA repair mechanism. In summary, reversine can increase the plasticity of sheep fibroblasts and suppress cell growth via the mitochondria mediated intrinsic pathway.

Biocompatibility Evolves: Phenomenology to Toxicology to Regeneration

The word "biocompatibility," is inconsistent with the observations of healing for so-called biocompatible biomaterials. The vast majority of the millions of medical implants in humans today, presumably "biocompatible," are walled off by a dense, avascular, crosslinked collagen capsule, hardly suggestive of life or compatibility. In contrast, one is now seeing examples of implant biomaterials that lead to a vascularized reconstruction of localized tissue, a biological reaction different from traditional biocompatible materials that generate a foreign body capsule. Both the encapsulated biomaterials and the reconstructive biomaterials qualify as "biocompatible" by present day measurements of biocompatibility. Yet, this new generation of materials would seem to heal "compatibly" with the living organism, where older biomaterials are isolated from the living organism by the dense capsule. This review/perspective article will explore this biocompatibility etymological conundrum by reviewing the history of the concepts around biocompatibility, today's standard methods for assessing biocompatibility, a contemporary view of the foreign body reaction and finally, a compendium of new biomaterials that heal without the foreign body capsule. A new definition of biocompatibility is offered here to address advances in biomaterials design leading to biomaterials that heal into the body in a facile manner.

Reversine: A Synthetic Purine with a Dual Activity as a Cell Dedifferentiating Agent and a Selective Anticancer Drug

The development of new therapeutic applications for adult and embryonic stem cells has dominated regenerative medicine and tissue engineering for several decades. However, since 2006, induced Pluripotent Stem Cells (iPSCs) have taken center stage in the field, as they promised to overcome several limitations of the other stem cell types. Nonetheless, other promising approaches for adult cell reprogramming have been attempted over the years, even before the generation of iPSCs. In particular, two years before the discovery of iPSCs, the possibility of synthesizing libraries of large organic compounds, as well as the development of high-throughput screenings to quickly test their biological activity, enabled the identification of a 2,6-disubstituted purine, named reversine, which was shown to be able to reprogram adult cells to a progenitor-like state. Since its discovery, the effect of reversine has been confirmed on different cell types, and several studies on its mechanism of action have revealed its central role in inhibitory activity on several kinases implicated in cell cycle regulation and cytokinesis. These key features, together with its chemical nature, suggested a possible use of the molecule as an anti-cancer drug. Remarkably, reversine exhibited potent cytotoxic activity against several tumor cell lines in vitro and a significant effect in decreasing tumor progression and metastatization in vivo. Thus, 15 years since its discovery, this review aims at critically summarizing the current knowledge to clarify the dual role of reversine as a dedifferentiating agent and anti-cancer drug.

Effects of Different Concentrations of Reversine on Plasticity of Mesenchymal Stem Cells

Dedifferentiation can be induced by small molecules. One of these small molecules used in this study in order to increase the plasticity of differentiation of stem cells was reversine. The objective of present study was to investigate the effect of different concentrations of reversine on the plasticity of ovine fetal bone-marrow mesenchymal stem cells (BM-MSCs). BM-MSCs were extracted from ovine fetal and cultured. Passaged-3 cells were evaluated for their differentiation potential into osteocytes and adipocytes cells. In the present study, BM-MSCs were culture plated in the presence of 0, 300, 600, 900 and 1200 nM of reversine. The number of viable cells was determined by MTT test after addition of different concentrations of reversine. Furthermore, expression of the nanog gene was evaluated. The culture without reversine was taken as the control group. Expression of nanog was analysed by immunocytochemistry. Multi-lineage differentiation showed that the BM-MSCs could be differentiated into adipose cells and osteocytes. Our results indicated that the addition of 1200 nM of reversine to medium significantly decreased overall proliferation compared to the other treatment groups (p > 0.05). Real-time PCR analysis showed that after addition of 600 nM of reversine significantly increased nanog expression compared to other treatments. All treatments received reversine were seen to be relative expression of nanog. Our findings confirm that low concentrations reversine increases the plasticity of ovine BM-MSCs.

Reversine increases the plasticity of lineage-committed preadipocytes to osteogenesis by inhibiting adipogenesis through induction of TGF-β pathway in vitro

Reversine has been reported to reverse differentiation of lineage-committed cells to mesenchymal stem cells (MSCs), which then enables them to be differentiated into other various lineages. Both adipocytes and osteoblasts are known to originate from common MSCs, and the balance between adipogenesis and osteogenesis in MSCs is reported to modulate the progression of various human diseases, such as obesity and osteoporosis. However, the role of reversine in modulating the adipogenic potential of lineage-committed preadipocytes and their plasticity to osteogenesis is unclear. Here we report that reversine has an anti-adipogenic function in 3T3-L1 preadipocytes in vitro and alters cell morphology and viability. The transforming growth factor-β (TGF-β) pathway appears to be required for the anti-adipogenic effect of reversine, due to reversine-induced expression of genes involved in TGF-β pathway and reversal of reversine-inhibited adipogenesis by inhibition of TGF-β pathway. We show that treatment with reversine transformed 3T3-L1 preadipocytes into MSC-like cells, as evidenced by the expression of MSCs marker genes. This, in turn, allowed differentiation of lineage-committed 3T3-L1 preadipocytes to osteoblasts under the osteogenic condition in vitro. Collectively, these findings reveal a new function of reversine in reversing lineage-committed preadipocytes to osteogenesis in vitro, and provide new insights into adipose tissue-based regeneration of osteoblasts.