Use of a PTFE Micro-Bioreactor to Promote 3D Cell Rearrangement and Maintain High Plasticity in Epigenetically Erased Fibroblasts

Phenotype definition is driven by epigenetic mechanisms as well as directly influenced by the cell microenvironment and by biophysical signals deriving from the extracellular matrix. The possibility to interact with the epigenetic signature of an adult mature cell, reversing its differentiated state and inducing a short transient high plasticity window, was previously demonstrated. In parallel, in vitro studies have shown that 3D culture systems, mimicking cell native tissue, exert significant effects on cell behavior and functions. Here we report the production of "PTFE micro-bioreactors" for long-term culture of epigenetically derived high plasticity cells. The system promotes 3D cell rearrangement, global DNA demethylation and elevated transcription of pluripotency markers, that is dependent on WW domain containing transcription regulator 1 (TAZ) nuclear accumulation and SMAD family member 2 (SMAD2) co-shuttling. Our findings demonstrate that the use of 3D culture strategies greatly improves the induction and maintenance of a high plasticity state.

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

In the presence of different environmental cues that are able to trigger specific responses, a given genotype has the ability to originate a variety of different phenotypes. This property is defined as plasticity and allows cell fate definition and tissue specialization. Fundamental epigenetic mechanisms drive these modifications in gene expression and include DNA methylation, histone modifications, chromatin remodeling, and microRNAs. Understanding these mechanisms can provide powerful tools to switch cell phenotype and implement cell therapy. Environmentally influenced epigenetic changes have also been associated to many diseases such as cancer and neurodegenerative disorders, with patients that do not respond, or only poorly respond, to conventional therapy. It is clear that disorders based on an individual's personal genomic/epigenomic profile can rarely be successfully treated with standard therapies due to genetic heterogeneity and epigenetic alterations and a personalized medicine approach is far more appropriate to manage these patients. We here discuss the recent advances in small molecule approaches for personalized medicine, drug targeting, and generation of new cells for medical application. We also provide prospective views of the possibility to directly convert one cell type into another, in a safe and robust way, for cell-based clinical trials and regenerative medicine.

Use of a Super-hydrophobic Microbioreactor to Generate and Boost Pancreatic Mini-organoids

Cell remarkable ability to self-organize and rearrange in functional organoids has been greatly boosted by the recent advances in 3-D culture technologies and materials. This approach can be presently applied to model human organ development and function "in a dish" and to predict drug response in a patient specific fashion.Here we describe a protocol that allows for the derivation of functional pancreatic mini-organoids from skin biopsies. Cells are suspended in a drop of medium and encapsulated with hydrophobic polytetrafluoroethylene (PTFE) powder particles, to form microbioreactors defined as "Liquid Marbles," that stimulate cell coalescence and 3-D aggregation. The PTFE shell ensures an optimal gas exchange between the interior liquid and the surrounding environment. It also makes it possible to scale down experiments and work in smaller volumes and is therefore amenable for higher throughput applications.

Methylation mechanisms and biomechanical effectors controlling cell fate

Mammalian development and cell fate specification are controlled by multiple regulatory mechanisms that interact in a coordinated way to ensure proper regulation of gene expression and spatial restriction, allowing cells to adopt distinct differentiation traits and a terminal phenotype. For example, cell potency is modulated by changes in methylation that are under the control of methyltransferases and ten–eleven translocation (TET) enzymes, which establish or erase a phenotype-specific methylation pattern during embryo development and mesenchymal to epithelial transition (MET). Cell plasticity is also responsive to extracellular factors, such as small molecules that interact with cell fate definition and induce a transient pluripotent state that allows the direct conversion of an adult mature cell into another differentiated cell type. In addition, cell-secreted vesicles emerge as powerful effectors, capable of modifying cell function and phenotype and delivering different signals, such as octamer-binding transcription factor-4 (Oct4) and SRY (sex determining region Y)-box 2 (Sox2) mRNAs (implicated in the preservation of pluripotency), thus triggering epigenetic changes in the recipient cells. In parallel, mechanical properties of the cellular microenvironment and three-dimensional rearrangement can affect both cell potency and differentiation through marked effects on cytoskeletal remodelling and with the involvement of specific mechanosensing-related pathways.

Adding a dimension to cell fate

Cell fate specification, gene expression and spatial restriction are process finely tuned by epigenetic regulatory mechanisms. At the same time, mechanical forces have been shown to be crucial to drive cell plasticity and boost differentiation. Indeed, several studies have demonstrated that transitions along different specification states are strongly influenced by 3D rearrangement and mechanical properties of the surrounding microenvironment, that can modulate both cell potency and differentiation, through the activation of specific mechanosensing-related pathways. An overview of small molecule ability to modulate cell plasticity and define cell fate is here presented and results, showing the possibility to erase the epigenetic signature of adult dermal fibroblasts and convert them into insulin-producing cells (EpiCC) are described. The beneficial effects exerted on such processes, when cells are homed on an adequate substrate, that shows “in vivo” tissue-like stiffness are also discussed and the contribution of the Hippo signalling mechano-transduction pathway as one of the mechanisms involved is examined. In addition, results obtained using a genetically modified fibroblast cell line, expressing the enhanced green fluorescent protein (eGFP) under the control of the porcine insulin gene (INS) promoter (INS-eGFP transgenic pigs), are reported. This model offers the advantage to monitor the progression of cell conversion in real time mode. All these observations have a main role in order to allow a swift scale-up culture procedure, essential for cell therapy and tissue engineering applied to human regenerative medicine, and fundamental to ensure an efficient translation process from the results obtained at the laboratory bench to the patient bedside. Moreover, the creation of reliable in vitro model represents a key point to ensure the development of more physiological models that, in turn, may reduce the number of animals used, implementing non-invasive investigations and animal welfare and protection.

Target-the-Two: a lab-in-the-field experiment on routinization

The paper investigates the cognitive determinants of routinization and creativity by means of a lab-in-the-field experiment run at the 20th edition of a mass gathering festival in Italy ("La Notte della Taranta"). Subjects play repeatedly the puzzle version of the Target-The-Two game (32 hands). In hands 1-16, the strategy that is optimal given the card distribution is always the same and it is the easiest to be discovered. Conversely, in hands 17-32, subjects are exposed to games where the optimal contextual strategy may differ from the one with which they have been made familiar. We investigate whether and how, in hands 17-32, subjects remain routinized on the familiar strategy, or creatively choose a different one. We define as "experts" those subjects who played the optimal contextual strategy in the overwhelming majority of hands 1-16. In hands 17-32, we find several subjects playing the familiar strategy even when it is not the optimal one, regardless of whether they are experts or not. This shows that routinization is deep-rooted in the cognitive individual process. Furthermore, routinization pays off only for inexpert subjects: creative inexpert subjects are slower and they fail to find the optimal contextual strategy in several hands. Among expert subjects instead, creative subjects, although still slower, need less moves than routinized ones to find the optimal contextual strategy.