Engineering exosomes derived from subcutaneous fat MSCs specially promote cartilage repair as miR-199a-3p delivery vehicles in Osteoarthritis.

Osteoarthritis (OA) is a degenerative joint disease involving cartilage. Exosomes derived from Mesenchymal stem cells (MSCs) therapy improves articular cartilage repair, but subcutaneous fat (SC) stromal cells derived exosomes (MSCsSC-Exos), especially engineering MSCsSC-Exos for drug delivery have been rarely reported in OA therapy. This objective of this study was to clarify the underlying mechanism of MSCsSC-Exos on cartilage repair and therapy of engineering MSCsSC-Exos for drug delivery in OA. MSCsSC-Exos could ameliorate the pathological severity degree of cartilage via miR-199a-3p, a novel molecular highly enriched in MSCsSC-Exos, which could mediate the mTOR-autophagy pathway in OA rat model. Intra-articular injection of antagomiR-199a-3p dramatically attenuated the protective effect of MSCsSC-Exos-mediated on articular cartilage in vivo. Furthermore, to achieve the superior therapeutic effects of MSCsSC-Exos on injured cartilage, engineering exosomes derived from MSCsSC as the chondrocyte-targeting miR-199a-3p delivery vehicles were investigated in vitro and in vivo. The chondrocyte-binding peptide (CAP) binding MSCsSC-Exos could particularly deliver miR-199a-3p into the chondrocytes in vitro and into deep articular tissues in vivo, then exert the excellent protective effect on injured cartilage in DMM-induced OA mice. As it is feasible to obtain human subcutaneous fat from healthy donors by liposuction operation in clinic, meanwhile engineering MSCsSC-Exos to realize targeted delivery of miR-199a-3p into chondrocytes exerted excellent therapeutic effects in OA animal model in vivo. Through combining MSCsSC-Exos therapy and miRNA therapy via an engineering approach, we develop an efficient MSCsSC-Exos-based strategy for OA therapy and promote the application of targeted-MSCsSC-Exos for drug delivery in the future.

ADSCs increase the autophagy of chondrocytes through decreasing miR-7-5p in Osteoarthritis rats by targeting ATG4A.

BACKGROUND: Osteoarthritis (OA) is a highly degenerative joint disease, mainly companying with progressive destruction of articular cartilage. Adipose-derived stromal cells (ADSCs) therapy enhances articular cartilage repair, extracellular matrix (ECM) synthesis and attenuates joints inflammation, but specific mechanisms of therapeutic benefit remain poorly understood. This study aimed to clarify the therapeutic effects and mechanisms of ADSCs on cartilage damage in the keen joint of OA rat model. METHODS: Destabilization of the medial meniscus (DMM) and anterior cruciate ligament transection (ACLT) surgery-induced OA rats were treated with allogeneic ADSCs by intra-articular injections for 6 weeks. The protective effect of ADSCs in vivo was measured using Safranin O and fast green staining, immunofluorescence and western blot analysis. Meanwhile, the miRNA-7-5p (miR-7-5p) expression was assessed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The mechanism of increased autophagy with ADSCs addition through decreasing miR-7-5p was revealed using oligonucleotides, and adenovirus in rat chondrocytes. The luciferase reporter assay revealed the molecular role of miR-7-5p and autophagy related 4A (ATG4A). The substrate of mTORC1 pathway: (p-)p70S6 and (p-)S6 in OA models with ADSCs addition were detected by western blotting. RESULTS: The ADSCs treatment repaired the articular cartilage and maintained chondrocytes ECM homeostasis through modulating chondrocytes autophagy in the OA model, indicators of the change of autophagic proteins expression and autophagic flux. Meanwhile, the increased autophagy induced by ADSCs treatment was closely related to the decreased expression of host-derived miR-7-5p, a negative modulator of OA progression. Functional genomics (overexpression of genes) in vitro studies demonstrate the inhibition of host-derived miR-7-5p in mediating the benefit of ADSCs administration in OA model. Then ATG4A was defined as a target gene of miR-7-5p, and the negative relation between miR-7-5p and ATG4A was investigated in the OA model treated with ADSCs. Furthermore, miR-7-5p mediated chondrocyte autophagy by targeting ATG4A in the OA model treated with ADSCs was confirmed with the rescue trial of ATG4A/miR-7-5p overexpression on rat chondrocyte. Finally, the mTORC1 signaling pathways mediated by host-derived miR-7-5p with ADSCs treatment were decreased in OA rats. CONCLUSIONS: ADSCs promote the chondrocytes autophagy by decreasing miR-7-5p in articular cartilage by targeting ATG4A and a potential role for ADSCs based therapeutics for preventing of articular cartilage destruction and extracellular matrix (ECM) degradation in OA.

Adipose-derived stem cells show hepatic differentiation potential and therapeutic effect in rats with acute liver failure.

Hepatocyte transplantation contributes to the repair of liver damage, but hepatocyte resources are limited, making it difficult for this to become a routine treatment. Previous studies have confirmed that mesenchymal stem cells (MSCs) can be induced to differentiate into hepatocyte-like cells (HLCs) by adding different cytokine combinations in vitro, and they then play some roles of hepatocytes. Our previous studies found that the differentiation ability of stem cells is closely related to the origin of the tissue. To identify the mesenchymal stem cells that are most suitable for hepatic differentiation and the treatment of liver failure, we use a three-phase induction process in which human adipose-derived stem cells (hADSCs) and umbilical cord mesenchymal stem cells (hUCMSCs) are induced to differentiate towards HLCs in vitro, and rats with acute liver failure (ALF) induced by D-gal are cured by MSCs and MSC-derived HLCs (MSCs-HLC), respectively. We find that hADSCs are stronger than hUCMSCs in hepatic differentiation ability, and they have a better curative effect when using hADSCs-HLC or jointly using hADSCs and hADSCs-HLC, which has positive significance for hepatocyte regeneration, recovery of liver function and reduction of systemic inflammatory reaction, finally improving the survival rate of rats with acute liver failure.

Cathepsin L-containing exosomes from α-synuclein-activated microglia induce neurotoxicity through the P2X7 receptor.

Uncontrolled microglial activation is pivotal to the pathogenesis of Parkinson's disease (PD), which can secrete Cathepsin L (CTSL) to affect the survival of neurons in the PD patients; however, the precise mechanism has yet to be determined. We demonstrated for the first time that CTSL was mostly released by exosomes derived from α-Syn-activated microglia, resulting in neuronal damage and death. The elevation of CTSL activity was blocked by GW4869, suggesting a critical role for exosomes in mediating CTSL release. Furthermore, the P2X7R/PI3K/AKT signalling pathway was identified as the underlying molecular mechanism since specific antagonists of this signalling pathway, P2X7R knockdown and exosome release inhibitors significantly reduced the injury to cultured mouse cortical neurons. Our study suggests that increased extracellular release of CTSL from α-Syn-activated microglia through exosomes amplifies and aggravates of the neurotoxic effect of microglia, implying that CTSL may be involved in a fresh mechanism of PD pathogenesis, and serve as a potential biomarker and a target for PD drug development.

Therapeutic Effects of Synthetic Triblock Amphiphilic Short Antimicrobial Peptides on Human Lung Adenocarcinoma.

Because of their unique properties, antimicrobial peptides (AMPs) represent a potential reservoir of novel anticancer therapeutic agents. However, only a few AMPs can kill tumors with high efficiency, and obtaining inexpensive anticancer AMPs with strong activity is still a challenge. In our previous work, a series of original short amphiphilic triblock AMP (KnFmKn) analogues were developed which were demonstrated to exert excellent effects on bacterial infection, both in vitro and in vivo. Herein, the overall objectives were to assess the potent tumoricidal capacities of these analogues against human lung cancer cell line A549 and the underlying mechanism. The results of the CCK-8 assay revealed that the precise modification of the peptides' primary sequences could modulate their tumoricidal potency. In the tumoricidal progress, positive charge and hydrophobicity were the key driving forces. Among these peptides, K4F6K4 displayed the most remarkable tumoricidal activity. Furthermore, the excellent anticancer capacity of K4F6K4 was proven by the live/dead cell staining, colony formation assay, and tumor growth observations on xenografted mice, which indicated that K4F6K4 might be a promising drug candidate for lung cancer, with no significant adverse effects in vitro or in vivo. In addition, the cell apoptosis assay using flow cytometry, the morphology observations using the optical microscope, confocal microscopy using CellMask™ Deep Red staining, and scanning electron microscope suggested that membrane disruption was the primary mechanism of its antitumor action. Through analyzing the structure-activity relationship, it was found that the amount of positive charge required for KnFmKn to exert its optimal tumoricidal effect was more than that needed for the antimicrobial activity, while the optimal proportion of hydrophobicity was less. Our findings suggest that further analysis of the structure-activity relationship of AMPs' primary sequence variations will be beneficial. Hopefully, this work can provide guiding principles in designing peptide-based therapeutics for lung cancer.

Sirt1 Protects Subventricular Zone-Derived Neural Stem Cells from DNA Double-Strand Breaks and Contributes to Olfactory Function Maintenance in Aging Mice.

DNA damage is assumed to accumulate in stem cells over time and their ability to withstand this damage and maintain tissue homeostasis is the key determinant of aging. Nonetheless, relatively few studies have investigated whether DNA damage does indeed accumulate in stem cells and whether this contributes to stem cell aging and functional decline. Here, we found that, compared with young mice, DNA double-strand breaks (DSBs) are reduced in the subventricular zone (SVZ)-derived neural stem cells (NSCs) of aged mice, which was achieved partly through the adaptive upregulation of Sirt1 expression and non-homologous end joining (NHEJ)-mediated DNA repair. Sirt1 deficiency abolished this effect, leading to stem cell exhaustion, olfactory memory decline, and accelerated aging. The reduced DSBs and the upregulation of Sirt1 expression in SVZ-derived NSCs with age may represent a compensatory mechanism that evolved to protect stem cells from excessive DNA damage, as well as mitigate memory loss and other stresses during aging.

ATM modulates subventricular zone neural stem cell maintenance and senescence through Notch signaling pathway.

Ataxia telangiectasia mutated (ATM) plays an essential role in DNA damage response and the maintenance of genomic stability. However, the role of ATM in regulating the function of adult neural stem cells (NSCs) remains unclear. Here we report that ATM deficiency led to accumulated DNA damage and decreased DNA damage repair capacity in neural progenitor cells. Moreover, we observed ATM ablation lead to the short-term increase of proliferation of neural progenitor cells, resulting in the depletion of the NSC pool over time, and this loss of NSC quiescence resulted in accelerated cell senescence. We further apply RNA sequencing to unravel that ATM knockout significantly affected Notch signaling pathway, furthermore, notch activation inhibit the abnormal increased proliferation of ATM-/- NSCs. Taken together, these findings indicate that ATM can serve as a key regulator for the normal function of adult NSCs by maintaining their stemness and preventing cellular senescence primarily through Notch signaling pathway.

Dynamic-Inspired Perspective on the Molecular Inhibitor of Tau Aggregation by Glucose Gallates Based on Human Neurons.

A molecular inhibitor of tau protein aggregation offers an attractive therapeutic possibility as disease-modifying treatment of Alzheimer's disease. However, the ineffectiveness as well as adjoint toxicity due to superficial understanding of the inhibition mechanism has hindered drug development. Conventional approaches for screening drug ligands rely on compatible docking with the well-defined structure of a protein receptor. Therefore, the design of tau aggregation inhibitors has been inevitably hindered by the unstructured, highly dynamic nature of the tau protein. This paper suggested a new strategy for reducing tau aggregation through a dynamic process of conformational isomerization. A group of glucose gallate derivatives were selected as tau aggregation inhibitors. These star-shaped molecules have a biocompatible glucose core surrounded by several gallic acid polyphenol arms, which can bind to peptide chains at different sites, probably through hydrogen bonds and π-π stacking. Theoretically, by elevating the saddle point on the potential energy surfaces (PES) of proteins, the barrier in the dynamic pathway of peptide isomerization, glucose gallates effectively inhibit tau aggregation through a dynamic mechanism. A tau cell model based on human neurons was constructed. For the first time, we confirmed that the moderate thermodynamic binding of the molecular ligand to the tau peptide chain can not only prevent the isomerization of the peptide chain leading to aggregation but also avoid toxicity resulting from the dissociation of tau from microtubules.

New Strategy for Reducing Tau Aggregation Cytologically by A Hairpinlike Molecular Inhibitor, Tannic Acid Encapsulated in Liposome.

Inhibition of Tau protein aggregation is an attractive therapeutic target for Alzheimer's disease. However, most of the inhibitors have failed in clinical trials due to the superficial understanding of inhibition mechanism and drug-transfer pharmacokinetics. Innovation of design strategy has become a top priority. To afford a hairpinlike molecular inhibitor, we introduced tannic acid, a multibranched polyphenol molecule, and its moiety, gallic acid. We showed that tannic acid could effectively inhibit Tau aggregation through a multidentate chelation mode. We then encapsulated tannic acid in a non-neurotoxic liposome by lecithin/ß-sitosterol, overcoating with Tween 80. Using transwell devices, we cytologically demonstrated that tannic acid liposome can successfully be transferred across the model of a blood-brain barrier made up of mouse brain microvascular endothelial cell bEnd.3 and effectively reduce Tau aggregation induced by fibrils of Tau peptide R3 in human neuroblastoma cell SK-N-SH. This result indicates the potential therapeutic effect of tannic acid liposome on Alzheimer's disease.

Differentiation of human adipose-derived stem cells into neuron/motoneuron-like cells for cell replacement therapy of spinal cord injury.

Human adipose-derived stem cells (hADSCs) are increasingly presumed to be a prospective stem cell source for cell replacement therapy in various degenerative and/or traumatic diseases. The potential of trans-differentiating hADSCs into motor neuron cells indisputably provides an alternative way for spinal cord injury (SCI) treatment. In the present study, a stepwise and efficient hADSC trans-differentiation protocol with retinoic acid (RA), sonic hedgehog (SHH), and neurotrophic factors were developed. With this protocol hADSCs could be converted into electrophysiologically active motoneuron-like cells (hADSC-MNs), which expressed both a cohort of pan neuronal markers and motor neuron specific markers. Moreover, after being primed for neuronal differentiation with RA/SHH, hADSCs were transplanted into SCI mouse model and they survived, migrated, and integrated into injured site and led to partial functional recovery of SCI mice. When ablating the transplanted hADSC-MNs harboring HSV-TK-mCherry overexpression system with antivirial Ganciclovir (GCV), functional relapse was detected by motor-evoked potential (MEP) and BMS assays, implying that transplanted hADSC-MNs participated in rebuilding the neural circuits, which was further confirmed by retrograde neuronal tracing system (WGA). GFP-labeled hADSC-MNs were subjected to whole-cell patch-clamp recording in acute spinal cord slice preparation and both action potentials and synaptic activities were recorded, which further confirmed that those pre-conditioned hADSCs indeed became functionally active neurons in vivo. As well, transplanted hADSC-MNs largely prevented the formation of injury-induced cavities and exerted obvious immune-suppression effect as revealed by preventing astrocyte reactivation and favoring the secretion of a spectrum of anti-inflammatory cytokines and chemokines. Our work suggests that hADSCs can be readily transformed into MNs in vitro, and stay viable in spinal cord of the SCI mouse and exert multi-therapeutic effects by rebuilding the broken circuitry and optimizing the microenvironment through immunosuppression.

Stress-induced precocious aging in PD-patient iPSC-derived NSCs may underlie the pathophysiology of Parkinson's disease.

Parkinson's disease (PD) is an aging-related degenerative disorder arisen from the loss of dopaminergic neurons in substantia nigra. Although many genetic mutations have been implicated to be genetically linked to PD, the low incidence of familial PD carried with mutations suggests that there must be other factors such as oxidative stress, mitochondrial dysfunction, accumulation of misfolded proteins, and enhanced inflammation, which are contributable to the pathophysiology of PD. The major efforts of current research have been devoted to unravel the toxic effect of multiple factors, which directly cause the degeneration of dopaminergic neurons in adulthood. Until recently, several studies have demonstrated that NSCs had compromised proliferation and differentiation capacity in PD animal models or PD patient-derived iPS models, suggesting that the pathology of PD may be rooted in some cellular aberrations at early developmental stage but the mechanism remains to be elusive. Based on the early-onset PD patient-specific iPSCs, we found that PD-patient iPSC-derived NSCs were more susceptible to stress and became functionally compromised by radiation or oxidative insults. We further unraveled that stress-induced SIRT1 downregulation leading to autophagic dysfunction, which were responsible for these deficits in PD-NSCs. Mechanistically, we demonstrated that stress-induced activation of p38 MAPK suppressed SIRT1 expression, which in turn augmented the acetylation of multiple ATG proteins of autophagic complex and eventually led to autophagic deficits. Our studies suggest that early developmental deficits may, at least partially, contribute to the pathology of PD and provide a new avenue for developing better therapeutic interventions to PD.

Astrocytic miR-324-5p is essential for synaptic formation by suppressing the secretion of CCL5 from astrocytes.

There is accumulating evidence that astrocytes play an important role in synaptic formation, plasticity, and pruning. Dicer and the fine-tuning of microRNA (miRNA) network are important for maintaining the normal functions of central nervous system and dysregulation of miRNAs is implicated in neurological disorders. However, little is known about the role of Dicer and miRNAs of astrocytes in the homeostasis of synapse as well as its plasticity. By selectively deleting Dicer in postnatal astrocytes, Dicer-deficient mice exhibited reactive astrogliosis and deficits in dendritic spine formation. Astrocyte-conditioned medium (ACM) collected from Dicer-null astrocytes caused synapse degeneration in cultured primary neurons. The expression of chemokine ligand 5 (CCL5) elevated in Dicer-deleted astrocytes which led to the significant augmentation of secreted CCL5 in ACM. In neurons treated with Dicer KO-ACM, CCL5 supplementation inhibited MAPK/CREB signaling pathway and exacerbated the synaptic formation deficiency, while CCL5 knockdown partially rescued the synapse degeneration. Moreover, we validated CCL5 as miR-324-5p targeted gene. ACM collected from miR-324-5p antagomir-transfected astrocytes mimicked the effect of CCL5 treatment on inhibiting synapse formation and MAPK/CREB signaling in Dicer KO-ACM-cocultured neurons. Furthermore, decreased miR-324-5p expression and elevated CCL5 expression were observed in the brain of aging mice. Our work reveals the non-cell-autonomous roles of astroglial miRNAs in regulation of astrocytic secretory milieu and neuronal synaptogenesis, implicating the loss or misregulation of astroglial miRNA network may contribute to neuroinflammation, neurodegeneration, and aging.

Extracellular Vesicles Secreted by Human Adipose-derived Stem Cells (hASCs) Improve Survival Rate of Rats with Acute Liver Failure by Releasing lncRNA H19.

It has previously been reported that human adipose-derived stem cells (hASCs) can promote the regeneration of damaged tissues in rats with liver failure through a 'paracrine effect'. Here we demonstrate a therapeutic effect of hASCs derived Extracellular Vesicles (EVs) on rat models with acute liver failure, as shown by the improvement of the survival rate by >70% compared to controls. Gene sequencing of rat liver revealed an increase in human long-chain non-coding RNA (lncRNA) H19 after hASC-derived EVs transplantation. When the H19 coding sequence was silenced in hASCs and EVs were then collected for treatment of rats with liver failure, we saw a decrease in the survival rate to 40%, compared to treatment with EVs generated from non-silenced hASCs. These data indicate that lncRNA H19 may be a potential therapeutic target for the treatment of liver failure.

SIRT1 Involved in the Regulation of Alternative Splicing Affects the DNA Damage Response in Neural Stem Cells.

BACKGROUND/AIMS: Alternative splicing and DNA damage exhibit cross-regulation, with not only DNA damage inducing changes in alternative splicing, but alternative splicing itself possibly modulating the DNA damage response (DDR). Sirt1, a prominent anti-aging player, plays pivotal roles in the DDR. However, few studies have examined alternative splicing with DNA damage in neural stem cells (NSCs) and, in essence, nothing is known about whether SIRT1 regulates alternative splicing. Hence, we investigated the potential involvement of Sirt1-mediated alternative splicing in the NSC DDR. METHODS: Genome-wide alternative splicing profiling was performed upon DNA damage induction and SIRT1 deletion. RESULTS: DNA damage caused genome-wide changes in alternative splicing in adult NSCs and Sirt1 deficiency dramatically altered DDR-related alternative splicing. In particular, extensive alternative splicing changes in DDR-related processes such as cell cycle control and DNA damage repair were observed; these processes were dramatically influenced by Sirt1 deficiency. Phenotypically, Sirt1 deficiency altered the proliferation and DNA repair of adult NSCs, possibly by regulating alternative splicing. CONCLUSION: SIRT1 helps to regulate alternative splicing, which itself affects the DDR of NSCs. Our findings provide novel insight into the mechanisms underlying the DDR in stem cells.

Regulation of multi-factors (tail/loop/link/ions) for G-quadruplex enantioselectivity of Δ- and Λ- [Ru(bpy)2(dppz-idzo)]2.

Chiral recognition of DNA molecules is important because much evidence has indicated that transformations of chirality and diverse conformations of DNA are involved in a series of key biological events. Among these, enrichment of G-quadruplexes (GQs) in the genome, and the exploration of their multiple structures, has aroused great interest. Herein, we compared nearly 100 different sequences with 3'-tail sequences of variable length or different linkers or diverse loops and mutative ionic concentrations. All sequences were capable of forming stable GQs, with fluorescence signal enhancement upon binding with Δ- and Λ- [Ru(bpy)2(dppz-idzo)]2+ (Δ/Λ-1). Our results show that multiple factors, including the 3'-tail length, linkers, loop length and ionic concentration, regulate the enantioselectivity of GQs. Furthermore, molecular docking simulations revealed that chiral recognition of GQs depends on the binding site. To the best of our knowledge, this is the first systematic study regarding the regulation of multi-factors for GQ selectivity of chiral Ru-complexes. These results will serve as a useful reference for enantioselective recognition of genomic GQs and may facilitate the development of chiral anticancer agents for targeting GQs.

Can arbuscular mycorrhizal fungi reduce Cd uptake and alleviate Cd toxicity of Lonicera japonica grown in Cd-added soils?

A greenhouse pot experiment was conducted to study the impact of arbuscular mycorrhizal fungi--Glomus versiforme (Gv) and Rhizophagus intraradices (Ri) on the growth, Cd uptake, antioxidant indices [glutathione reductase (GR), ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT), ascorbate (ASA), glutathione (GSH) and malonaldehyde (MDA)] and phytochelatins (PCs) production of Lonicera japonica in Cd-amended soils. Gv and Ri significantly increased P acquisition, biomass of shoots and roots at all Cd treatments. Gv significantly decreased Cd concentrations in shoots and roots, and Ri also obviously reduced Cd concentrations in shoots but increased Cd concentrations in roots. Meanwhile, activities of CAT, APX and GR, and contents of ASA and PCs were remarkably higher in Gv/Ri-inoculated plants than those of uninoculated plants, but lower MDA and GSH contents in Gv/Ri-inoculated plants were found. In conclusion, Gv and Ri symbiosis alleviated Cd toxicity of L. japonica through the decline of shoot Cd concentrations and the improvement of P nutrition, PCs content and activities of GR, CAT, APX in inoculated plants, and then improved plant growth. The decrease of shoot Cd concentrations in L. japonica inoculated with Gv/Ri would provide a clue for safe production of this plant from Cd-contaminated soils.

Dysfunction of autophagy as the pathological mechanism of motor neuron disease based on a patient-specific disease model.

Autophagy is the main catabolic pathway in cells for the degradation of impaired proteins and organelles. Accumulating evidence supports the hypothesis that dysfunction of autophagy, leading to an imbalance of proteostasis and the accumulation of toxic proteins in neurons, is a central player in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS). The clinical pathology of ALS is complex and many genes associated with autophagy and RNA processing are mutated in patients with the familial form. But a causal relationship between autophagic dysfunction and ALS has not been fully established. More importantly, studies on the pathological mechanism of ALS are mainly based on animal models that may not precisely recapitulate the disease itself in human beings. The development of human iPSC techniques allows us to address these issues directly in human cell models that may profoundly influence drug discovery for ALS.

Rejuvenation of MPTP-induced human neural precursor cell senescence by activating autophagy.

Aging of neural stem cell, which can affect brain homeostasis, may be caused by many cellular mechanisms. Autophagy dysfunction was found in aged and neurodegenerative brains. However, little is known about the relationship between autophagy and human neural stem cell (hNSC) aging. The present study used 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) to treat neural precursor cells (NPCs) derived from human embryonic stem cell (hESC) line H9 and investigate related molecular mechanisms involved in this process. MPTP-treated NPCs were found to undergo premature senescence [determined by increased senescence-associated-ß-galactosidase (SA-ß-gal) activity, elevated intracellular reactive oxygen species level, and decreased proliferation] and were associated with impaired autophagy. Additionally, the cellular senescence phenotypes were manifested at the molecular level by a significant increase in p21 and p53 expression, a decrease in SOD2 expression, and a decrease in expression of some key autophagy-related genes such as Atg5, Atg7, Atg12, and Beclin 1. Furthermore, we found that the senescence-like phenotype of MPTP-treated hNPCs was rejuvenated through treatment with a well-known autophagy enhancer rapamycin, which was blocked by suppression of essential autophagy gene Beclin 1. Taken together, these findings reveal the critical role of autophagy in the process of hNSC aging, and this process can be reversed by activating autophagy.

Differentiation of human adipose-derived stem cells into neuron-like cells which are compatible with photocurable three-dimensional scaffolds.

Multipotent human adipose-derived stromal/stem cells (hADSCs) hold a great promise for cell-based therapy for many devastating human diseases, such as spinal cord injury and stroke. If exogenous hADSCs can be cultured in a three-dimensional (3D) scaffold with effective proliferation and differentiation capacity, it will better mimic the in vivo environment, which will have profound impact on the therapeutic application of hADSCs. In this study, a group of elastic-dominant, porous bioscaffolds from photocurable chitosan and gelatin were fabricated and proven to be biocompatible with both hADSCs and hADSC-derived neuron-like cells (hADSC-NLCs) in vitro. The identity of harvested hADSCs was confirmed by their positive immunostaining of mesenchymal stem cell surface markers, CD29, CD44, and CD105, and also positive expression of stem markers, Sox-2, Oct-4, c-Myc, Nanog, and Klf4. Their multipotency was further confirmed by trilineage differentiation of hADSCs toward adipocyte, osteoblast, and chondrocyte. It was found that hADSCs could be conditioned to differentiate into neurons in vitro as determined by immunostaining the markers of Tuj1, MAP2, NeuN, and Synapsin. The hADSCs and hADSC-NLCs were proven to be biocompatible with 3D scaffold, which actually facilitated the proliferation and differentiation of hADSCs in vitro, by MTT assay and their neuronal gene expression profiling. Moreover, hADSC-NLCs, which were mixed with 3D scaffold and transplanted into traumatic brain injury mouse model, survived in vivo and led to the better repair of the damaged brain area. The immunohistochemical studies revealed that 3D scaffold indeed improved the viability of transplanted cells, their ability to incorporate into the in vivo neural circuit, and their capacity for tissue repair. This study indicates that hADSCs would have great therapeutic application potential as seeding cells for in vivo transplantation to treat various neurological diseases when co-applied with porous chitosan/gelatin bioscaffolds.