Generation of Dopamine-Secreting Cells from Human Adipose Tissue-Derived Stem Cells In Vitro

DNA Methyltransferase Inhibition by RG108 Improves Stemness and Multipotential Differentiation of Human Adipose Tissue-derived Stem Cells

Background

DNA methylation plays important roles in regulating various biological processes, including self-renewal, differentiation and regenerative capacity of stem cells. Previous studies have demonstrated that lineage-specific differentiation of mesenchymal stem cells can be promoted using nontoxic chromatin-modifying drugs.

Objectives

Here we evaluated the impact of RG108, a known DNA methyltransferase inhibitor, on the expression of pluripotency genes in human adipose tissue-derived stem cells (hADSCs) and their proliferation and differentiation.

Materials and Methods

Human ADSCs were isolated by collagenase treatment and characterized. Then, ADSCs were treated with 5 µM RG108 for four days. The control and RG108-treated cells were analyzed for the cell cycle progression, apoptosis and the expression of pluripotency genes. Also, ADSCs were cultured in adipogenic and osteogenic differentiation media for three weeks and were assessed by Oil Red O and Alizarin Red S staining and qPCR analysis.

Results

We showed that RG108 treatment increased proliferation of hADSCs and upregulated the expression of pluripotency-related genes. Additionally, RG108 had a positive impact on the differentiation capability of ADSCs. This was evident through elevated levels of Oil Red O staining in the RG108 treatment group. Also, qPCR analysis showed the upregulation of some adipogenic and osteogenic markers by RG108.

Conclusion

These findings indicate that pretreatment with RG108 improves the differentiation potential of ADSCs, probably making these cells more beneficial for cell therapy applications.

Neural Marker Expression in Adipose-Derived Stem Cells Grown in PEG-Based 3D Matrix Is Enhanced in the Presence of B27 and CultureOne Supplements

Adipose-derived stem cells (ADSCs) have incredible potential as an avenue to better understand and treat neurological disorders. While they have been successfully differentiated into neural stem cells and neurons, most such protocols involve 2D environments, which are not representative of in vivo physiology. In this study, human ADSCs were cultured in 1.1 kPa polyethylene-glycol 3D hydrogels for 10 days with B27, CultureOne (C1), and N2 neural supplements to examine the neural differentiation potential of ADSCs using both chemical and mechanical cues. Following treatment, cell viability, proliferation, morphology, and proteome changes were assessed. Results showed that cell viability was maintained during treatments, and while cells continued to proliferate over time, proliferation slowed down. Morphological changes between 3D untreated cells and treated cells were not observed. However, they were observed among 2D treatments, which exhibited cellular elongation and co-alignment. Proteome analysis showed changes consistent with early neural differentiation for B27 and C1 but not N2. No significant changes were detected using immunocytochemistry, potentially indicating a greater differentiation period was required. In conclusion, treatment of 3D-cultured ADSCs in PEG-based hydrogels with B27 and C1 further enhances neural marker expression, however, this was not observed using supplementation with N2.

Adipose-Derived Stem Cells Spontaneously Express Neural Markers When Grown in a PEG-Based 3D Matrix

Neurological diseases are among the leading causes of disability and death worldwide and remain difficult to treat. Tissue engineering offers avenues to test potential treatments; however, the development of biologically accurate models of brain tissues remains challenging. Given their neurogenic potential and availability, adipose-derived stem cells (ADSCs) are of interest for creating neural models. While progress has been made in differentiating ADSCs into neural cells, their differentiation in 3D environments, which are more representative of the in vivo physiological conditions of the nervous system, is crucial. This can be achieved by modulating the 3D matrix composition and stiffness. Human ADSCs were cultured for 14 days in a 1.1 kPa polyethylene glycol-based 3D hydrogel matrix to assess effects on cell morphology, cell viability, proteome changes and spontaneous neural differentiation. Results showed that cells continued to proliferate over the 14-day period and presented a different morphology to 2D cultures, with the cells elongating and aligning with one another. The proteome analysis revealed 439 proteins changed in abundance by >1.5 fold. Cyclic nucleotide 3'-phosphodiesterase (CNPase) markers were identified using immunocytochemistry and confirmed with proteomics. Findings indicate that ADSCs spontaneously increase neural marker expression when grown in an environment with similar mechanical properties to the central nervous system.

Current concepts of microRNA-mediated regulatory mechanisms in human pulp tissue-derived stem cells: a snapshot in the regenerative dentistry

One of the most studied class of non-coding RNAs is microRNAs (miRNAs) which regulate more than 60% of human genes. A network of miRNA gene interactions participates in stem cell self-renewal, proliferation, migration, apoptosis, immunomodulation, and differentiation. Human pulp tissue-derived stem cells (PSCs) are an attractive source of dental mesenchymal stem cells (MSCs) which comprise human dental pulp stem cells (hDPSCs) obtained from the dental pulp of permanent teeth and stem cells isolated from exfoliated deciduous teeth (SHEDs) that would be a therapeutic opportunity in stomatognathic system reconstruction and repair of other damaged tissues. The regenerative capacity of hDPSCs and SHEDs is mediated by osteogenic, odontogenic, myogenic, neurogenic, angiogenic differentiation, and immunomodulatory function. Multi-lineage differentiation of PSCs can be induced or inhibited by the interaction of miRNAs with their target genes. Manipulating the expression of functional miRNAs in PSCs by mimicking miRNAs or inhibiting miRNAs emerged as a therapeutic tool in the clinical translation. However, the effectiveness and safety of miRNA-based therapeutics, besides higher stability, biocompatibility, less off-target effects, and immunologic reactions, have received particular attention. This review aimed to comprehensively overview the molecular mechanisms underlying miRNA-modified PSCs as a futuristic therapeutic option in regenerative dentistry.

Dental follicle cells show potential for treating Parkinson's disease through dopaminergic-neuronogenic differentiation

Among all the adult stem cells, odontogenic stem cells inherit the characterization of neurogenic potential of their precursor ones-the cranial crest cells. Dental follicle cells (DFCs), one of the special kind of odontogenic stem cells, are raising interest in applying to regenerative medicine for they possess multi-differentiation potential, relatively free access and ethic-friendly characteristic. Parkinson's disease (PD), as one of the common neurodegenerative disorders, affects about 0.3% of the general population. Stem cell therapies are thought to be effective to treat it. Aiming at tackling ethical-concernings, confined sources and practically applicational limits, we made use of dopaminergic neurongenic differentiation potential of the DFCs and dedicated every effort to applying them as promising cell source for treating PD. Dental follicle cells were cultured from human dental follicle tissues collected from 12 to 18-year-old teenagers' completely impacted third molars. Our data demonstrated that hDFCs were expressing mesenchymal stem cell-associated surface markers, and possessed the ability of osteogenic, adipogenic and neurogenic differentiation in vitro. Additionally, hDFCs formed neuron-like cells in vitro and in vivo, as well as expressing dopaminergic-neuronogenic marker-TH. Moreover, hDFCs survived in the transplanted areas of the Parkinson's disease model of mouse over six weeks post-surgery, and the number of TH-positive DFCs in the DFCs-Grafted group surpassed its counterpart of the MPTP group with statistically significant difference. This study indicated that hDFCs might be a promising source of dopaminergic neurons for functional transplantation, and encouraged further detailed studies on the potential of hDFCs for treating PD.

Commentary on Some Recent Theses Relevant to Combating Aging: June 2020

Theses reviewed in this issue include "Clearance of Capillary Occlusions Improves Cortical Blood Flow and Cognitive Function in Alzheimer's Mouse Models," "Dermato-Informatic Approaches to Understanding and Improving Lesional Diagnostic Expertise in Cutaneous Oncology," "Furthering the Scope, Understanding, and Application of Proteolysis Targeting Chimera," "Optimization and Application of Synthetic High-Density Lipoprotein (sHDL) System in Atherosclerosis and Glioma Therapy," "Regulatory T Cell Enriching Microparticles for Promoting Tolerance in Vascularized Composite Allotransplantation," and "Tau Prion Strains Induce Distinct Pathological Phenotypes In Vivo."

Functional dopaminergic neurons derived from human chorionic mesenchymal stem cells ameliorate striatal atrophy and improve behavioral deficits in Parkinsonian rat model

Human chorionic mesenchymal stem cells (HCMSCs) have been recognized as a desirable choice for cell therapy in neurological disorders such as Parkinson's disease (PD). Due to invaluable features of HCMSCs including their immunomodulatory and immunosuppressive properties, easily accessible and less differentiated compared to other types of MSCs, HCMSCs provide a great hope for regenerative medicine. Thus, the purpose of this study was to determine the in vitro and in vivo efficacy of HCMSCs-derived dopaminergic (DA) neuron-like cells with regard to PD. Initially, HCMSCs were isolated and underwent a 2-week DA differentiation, followed by in vitro assessments, using quantitative real-time polymerase chain reaction, immunocytochemistry, patch clamp recording, and high-performance liquid chromatography. In addition, the effects of implanted HCMSCs-derived DA neuron-like cells on the motor coordination along with stereological alterations in the striatum of rat models of PD were investigated. Our results showed that under neuronal induction, HCMSCs revealed neuron-like morphology, and expressed neuronal and DA-specific genes, together with DA release. Furthermore, transplantation of HCMSCs-derived DA neurons into the striatum of rat models of PD, augmented performance. Besides, it prevented reduction of striatal volume, dendritic length, and the total number of neurons, coupled with a diminished level of cleaved caspase-3. Altogether, these findings suggest that HCMSCs could be considered as an attractive strategy for cell-based therapies in PD.

Cardiac Differentiation of Adipose Tissue-Derived Stem Cells Is Driven by BMP4 and bFGF but Counteracted by 5-Azacytidine and Valproic Acid

Objective

Bone morphogenetic protein 4 (BMP4) and basic fibroblast growth factor (bFGF) play important roles in embryonic heart development. Also, two epigenetic modifying molecules, 5'-azacytidine (5'-Aza) and valproic acid (VPA) induce cardiomyogenesis in the infarcted heart. In this study, we first evaluated the role of BMP4 and bFGF in cardiac trans-differentiation and then the effectiveness of 5´-Aza and VPA in reprogramming and cardiac differentiation of human adipose tissue-derived stem cells (ADSCs).

Materials and Methods

In this experimental study, human ADSCs were isolated by collagenase I digestion. For cardiac differentiation, third to fifth-passaged ADSCs were treated with BMP4 alone or a combination of BMP4 and bFGF with or without 5'-Aza and VPA pre-treatment. After 21 days, the expression of cardiac-specific markers was evaluated by reverse transcription polymerase chain reaction (RT-PCR), quantitative real-time PCR, immunocytochemistry, flow cytometry and western blot analyses.

Results

BMP4 and more prominently a combination of BMP4 and bFGF induced cardiac differentiation of human ADSCs. Epigenetic modification of the ADSCs by 5'-Aza and VPA significantly upregulated the expression of OCT4A, SOX2, NANOG, Brachyury/T and GATA4 but downregulated GSC and NES mRNAs. Furthermore, pre-treatment with 5'-Aza and VPA upregulated the expression of TBX5, ANF, CX43 and CXCR4 mRNAs in three-week differentiated ADSCs but downregulated the expression of some cardiac-specific genes and decreased the population of cardiac troponin I-expressing cells.

Conclusion

Our findings demonstrated the inductive role of BMP4 and especially BMP4 and bFGF combination in cardiac trans-differentiation of human ADSCs. Treatment with 5'-Aza and VPA reprogrammed ADSCs toward a more pluripotent state and increased tendency of the ADSCs for mesodermal differentiation. Although pre-treatment with 5'-Aza and VPA counteracted the cardiogenic effects of BMP4 and bFGF, it may be in favor of migration, engraftment and survival of the ADSCs after transplantation.

Directed differentiation of human adipose tissue-derived stem cells to dopaminergic neurons in low-serum and serum-free conditions

Directing the fate of mesenchymal stem cells (MSCs) to dopaminergic neurons has great importance in both biomedical studies and cell therapy of Parkinson's disease. We recently generated dopamine-secreting cells from human adipose tissue-derived stem cells (hADSCs) by exposing the cells to a growth factor cocktail composed of SHH, bFGF, FGF8 and BDNF in low-serum condition. In the current study, we induced the cells by the same dopaminergic inducing cocktail in serum-free B27-supplemented Neurobasal medium. ADSCs differentiated in both conditions expressed several neuronal and dopaminergic markers. However, there were higher gene expression levels under the serum-free condition. Higher levels of TUJ1 and TH proteins were also detected in the cells exposed to the dopaminergic-inducing cocktail under serum-free Neurobasal condition. TH protein was expressed in about 28% and 60% of the cells differentiated in the low-serum and serum-free Neurobasal media, respectively. Moreover, the cells exposed to the dopaminergic-inducing cocktail in the serum-free Neurobasal condition released a more significant amount of dopamine in response to KCl-induced depolarization. Altogether, these findings show a greater efficiency of the serum-free Neurobasal condition for growth factor-directed differentiation of hADSCs to functional dopamine-secreting cells which may be valuable for transplantation therapy of Parkinson's disease in future.

Gain-of-function KCNJ6 Mutation in a Severe Hyperkinetic Movement Disorder Phenotype

Here, we describe a fourth case of a human with a de novo KCNJ6 (GIRK2) mutation, who presented with clinical findings of severe hyperkinetic movement disorder and developmental delay, similar to the Keppen-Lubinsky syndrome but without lipodystrophy. Whole-exome sequencing of the patient's DNA revealed a heterozygous de novo variant in the KCNJ6 (c.512T>G, p.Leu171Arg). We conducted in vitro functional studies to determine if this Leu-to-Arg mutation alters the function of GIRK2 channels. Heterologous expression of the mutant GIRK2 channel alone produced an aberrant basal inward current that lacked G protein activation, lost K⁺ selectivity and gained Ca²⁺ permeability. Notably, the inward current was inhibited by the Na⁺ channel blocker QX-314, similar to the previously reported weaver mutation in murine GIRK2. Expression of a tandem dimer containing GIRK1 and GIRK2(p.Leu171Arg) did not lead to any currents, suggesting heterotetramers are not functional. In neurons expressing p.Leu171Arg GIRK2 channels, these changes in channel properties would be expected to generate a sustained depolarization, instead of the normal G protein-gated inhibitory response, which could be mitigated by expression of other GIRK subunits. The identification of the p.Leu171Arg GIRK2 mutation potentially expands the Keppen-Lubinsky syndrome phenotype to include severe dystonia and ballismus. Our study suggests screening for dominant KCNJ6 mutations in the evaluation of patients with severe movement disorders, which could provide evidence to support a causal role of KCNJ6 in neurological channelopathies.