Although somatic cells can be reprogrammed to pluripotent stem cells (PSCs) with pure chemicals, authentic pluripotency of chemically induced pluripotent stem cells (CiPSCs) has never been achieved through tetraploid complementation assay. Spontaneous reprogramming of spermatogonial stem cells (SSCs) was another non-transgenic way to obtain PSCs, but this process lacks mechanistic explanation. Here, we reconstructed the trajectory of mouse SSC reprogramming and developed a five-chemical combination, boosting the reprogramming efficiency by nearly 80- to 100-folds. More importantly, chemical induced germline-derived PSCs (5C-gPSCs), but not gPSCs and chemical induced pluripotent stem cells, had authentic pluripotency, as determined by tetraploid complementation. Mechanistically, SSCs traversed through an inverted pathway of in vivo germ cell development, exhibiting the expression signatures and DNA methylation dynamics from spermatogonia to primordial germ cells and further to epiblasts. Besides, SSC-specific imprinting control regions switched from biallelic methylated states to monoallelic methylated states by imprinting demethylation and then re-methylation on one of the two alleles in 5C-gPSCs, which was apparently distinct with the imprinting reprogramming in vivo as DNA methylation simultaneously occurred on both alleles. Our work sheds light on the unique regulatory network underpinning SSC reprogramming, providing insights to understand generic mechanisms for cell-fate decision and epigenetic-related disorders in regenerative medicine.
Male ; Mice ; Animals ; Cellular Reprogramming/genetics* ; Tetraploidy ; Pluripotent Stem Cells/metabolism* ; Induced Pluripotent Stem Cells/metabolism* ; DNA Methylation ; Spermatogonia/metabolism* ; Germ Cells/metabolism*

Animals ; Cellular Reprogramming ; DNA Methylation ; Epigenesis, Genetic ; Mice

The capacity for neurogenesis in the adult mammalian brain is extremely limited and highly restricted to a few regions, which greatly hampers neuronal regeneration and functional restoration after neuronal loss caused by injury or disease. Meanwhile, transplantation of exogenous neuronal stem cells into the brain encounters several serious issues including immune rejection and the risk of tumorigenesis. Recent discoveries of direct reprogramming of endogenous glial cells into functional neurons have provided new opportunities for adult neuro-regeneration. Here, we extensively review the experimental findings of the direct conversion of glial cells to neurons in vitro and in vivo and discuss the remaining issues and challenges related to the glial subtypes and the specificity and efficiency of direct cell-reprograming, as well as the influence of the microenvironment. Although in situ glial cell reprogramming offers great potential for neuronal repair in the injured or diseased brain, it still needs a large amount of research to pave the way to therapeutic application.
Animals ; Cellular Reprogramming ; Nerve Regeneration ; Neurogenesis ; Neuroglia ; Neurons

Central nervous system injury leads to irreversible neuronal loss and glial scar formation, which ultimately results in persistent neurological dysfunction. Regenerative medicine suggests that replenishing missing neurons may be an ideal approach to repair the damage. Recent researches showed that many mature cells could be transdifferentiated into functional neurons by reprogramming. Therefore, reprogramming endogenous glia in situ to produce functional neurons shows great potential and unique advantage for repairing neuronal damage and treating neurodegenerative diseases. The present review summarized the current research progress on in situ transdifferentiation in the central nervous system, focusing on the cell types, characteristics and research progress of glial cells that could be transdifferentiated in situ, in order to provide theoretical basis for the development of new therapeutic strategies of neuronal injury and further clinical application.
Cell Transdifferentiation ; Cellular Reprogramming ; Central Nervous System ; cytology ; Humans ; Neurodegenerative Diseases ; Neuroglia ; cytology ; Neurons ; cytology

The slow progress in clinical applications of stem cells and the bewildering mechanisms involved have puzzled many researchers. Recently, the increasing evidences have indicated that cells have superior plasticity in vivo or in vitro, spontaneously or under extrinsic specific inducers. The concept of stem cells may be challenged, or even replaced by the concept of cell plasticity when cell reprogramming technology is progressing rapidly. The characteristics of stem cells are manifestations of cellular plasticity. Incorrect understanding of the concept of stem cells hinders the clinical application of so-called stem cells. Understanding cellular plasticity is important for understanding and treating disease. The above issues will be discussed in detail to prove the reconceptualization of stem cells from cellular plasticity.
Cell Plasticity ; Cellular Reprogramming ; In Vitro Techniques ; Plastics ; Stem Cells

The concept of cellular reprogramming was developed to generate induced neural precursor cells (iNPCs)/dopaminergic (iDA) neurons using diverse approaches. Here, we investigated the effects of various nanoscale scaffolds (fiber, dot, and line) on iNPC/iDA differentiation by direct reprogramming. The generation and maturation of iDA neurons (microtubule-associated protein 2-positive and tyrosine hydroxylase-positive) and iNPCs (NESTIN-positive and SOX2-positive) increased on fiber and dot scaffolds as compared to that of the flat (control) scaffold. This study demonstrates that nanotopographical environments are suitable for direct differentiation methods and may improve the differentiation efficiency.
Cellular Reprogramming ; Nanofibers ; Neurons ; Tyrosine

This study examined the effects of a caffeine treatment to improve nuclear reprogramming in porcine cloned embryos. Embryonic development and the expression of genes related to pluripotency (POU5F1, SOX2, NANOG, and CDX2) were compared after caffeine supplementation during manipulation at different concentrations (0, 1.25, 2.5, and 5.0 mM) and after varying the delayed activation time (control, 1, 2, and 4 h) after fusion. Caffeine added to media during manipulation produced a higher rate of development to blastocysts in the 1.25 mM group than in the other concentration groups (22.8% vs. 16.1%, 16.2%, and 19.2%; p < 0.05). When caffeine was added during the 4 h delayed activation, the 1.25 mM caffeine concentration produced a significantly higher rate of development than those in the other 4 h-activation-delayed caffeine concentration groups (22.4% vs. 9.4%, 14.0%, and 11.1%; p < 0.05). On the other hand, no significant improvement over that in the control group was observed when caffeine was supplemented during both the manipulation period and delayed activation period (16.0% vs. 15.2%), respectively. The levels of POU5F1, SOX2, and NANOG expression in blastocysts were significantly higher in the delayed activation caffeine group (4 h, 1.25 mM) than in the control group (1 h, 0 mM; p < 0.05). In conclusion, a caffeine treatment at 1.25 mM during delayed activation for 4 h can improve the preimplantation development of porcine somatic cell nuclear transfer embryos by activating nuclear reprogramming.
Blastocyst ; Caffeine ; Cellular Reprogramming ; Clone Cells ; Embryonic Development ; Embryonic Structures ; Female ; Hand ; Pregnancy

BACKGROUND AND OBJECTIVES: Several recent studies have claimed that cancer cells can be reprogrammed into induced pluripotent stem cells (iPSCs). However, in most cases, cancer cells seem to be resistant to cellular reprogramming. Furthermore, the underlying mechanisms of limited reprogramming in cancer cells are largely unknown. Here, we identified the candidate barrier genes and their target genes at the early stage of reprogramming for investigating cancer reprogramming.METHODS: We tried induction of pluripotency in normal human fibroblasts (BJ) and both human benign (MCF10A) and malignant (MCF7) breast cancer cell lines using a classical retroviral reprogramming method. We conducted RNA-sequencing analysis to compare the transcriptome of the three cell lines at early stage of reprogramming.RESULTS: We could generate iPSCs from BJ, whereas we were unable to obtain iPSCs from cancer cell lines. To address the underlying mechanism of limited reprogramming in cancer cells, we identified 29 the candidate barrier genes based on RNA-sequencing data. In addition, we found 40 their target genes using Cytoscape software.CONCLUSIONS: Our data suggest that these genes might one of the roadblock for cancer cell reprogramming. Furthermore, we provide new insights into application of iPSCs technology in cancer cell field for therapeutic purposes.
Breast Neoplasms ; Cell Line ; Cellular Reprogramming ; Fibroblasts ; Humans ; Induced Pluripotent Stem Cells ; Methods ; Transcriptome ; Zidovudine

BACKGROUND AND OBJECTIVE: The potency of tissue resident stem cells is regulated primarily by inputs from the local microenvironment. Isolation of stem cells through enzymatic digestion of tissue may affect epigenetic regulation of cell fate and performance. Here we employ a non-enzymatic method to harvest and investigate tissue resident stem cells from the adult porcine pulmonary valve. METHODS AND RESULTS: The presence of c-Kit+ stem cells within the valve tissue was confirmed by immunohistochemistry. An in vitro culture of minced valve leaflets was developed under the standard conditions (37°C with 5% CO2). The viability of the cellular outgrowths was evaluated over the subsequent 12 weeks. Under this culture condition, we identified a population of non-adherent c-Kit+ cells and multiple cellular structures mimicking the phenotype of embryonic stem cells at different stages of development. Formation of multinucleated cells through cell fusion provided an active niche area for homing and interaction of the non-adherent c-Kit+ cells. Expression of pluripotency markers Oct-4 and Nanog was detected in the newly formed multinucleated cells but not in mature colonies. Partial cell fusion was shown by fluorescent live-cell tracking, which confirmed intercellular molecular exchange between donor and recipient cells, resulting in altered cytoplasmic protein expression by the recipient cell. CONCLUSIONS: These results suggest a role for the microenvironment in decrypting the potential of the valve somatic stem cells in vitro. In addition, our data provide evidence for cell fusion, which may play a critical role in reversing somatic cell fate and spontaneous cellular reprogramming.
Adult ; Cell Fusion ; Cellular Microenvironment ; Cellular Reprogramming ; Cellular Structures ; Cytoplasm ; Digestion ; Embryonic Stem Cells ; Epigenomics ; Heart Valves ; Humans ; Immunohistochemistry ; In Vitro Techniques ; Methods ; Phenotype ; Pulmonary Valve ; Stem Cells ; Tissue Donors

In regenerative medicine, growing cells or tissues in the laboratory is necessary when damaged cells can not heal by themselves. Acquisition of the required cells from the patient's own cells or tissues is an ideal option without additive side effects. In this context, cell reprogramming methods, including the use of induced pluripotent stem cells (iPSCs) and trans-differentiation, have been widely studied in regenerative research. Both approaches have advantages and disadvantages, and the possibility of de-differentiation because of the epigenetic memory of iPSCs has strengthened the need for controlling the epigenetic background for successful cell reprogramming. Therefore, interest in epigenetics has increased in the field of regenerative medicine. Herein, we outline in detail the cell trans-differentiation method using epigenetic modification for bone regeneration in comparison to the use of iPSCs.
Bone Regeneration ; Cell Transdifferentiation ; Cellular Reprogramming ; Epigenomics ; Induced Pluripotent Stem Cells ; Memory ; Methods ; Regenerative Medicine ; Tissue Engineering