Large extracellular vesicles secreted by human iPSC-derived MSCs ameliorate tendinopathy via regulating macrophage heterogeneity

Tendinopathy is a common musculoskeletal disorder which results in chronic pain and reduced performance.The therapeutic effect of stem cell derived-small extracellular vesicles(sEVs)for tendinopathy has been validated in recent years.However,whether large extracellular vesicles(lEVs),another subset of extracellular vesicles,possesses the ability for the improvement of tendinopathy remains unknown.Here,we showed that lEVs secreted from iPSC-derived MSCs(iMSC-lEVs)significantly mitigated pain derived from tendinopathy in rats.Immuno-histochemical analysis showed that iMSC-lEVs regulated the heterogeneity of infiltrated macrophages and several inflammatory cytokines in rat tendon tissue.Meanwhile,in vitro experiments revealed that the M1 pro-inflammatory macrophages were repolarized towards M2 anti-inflammatory macrophages by iMSC-lEVs,and this effect was mediated by regulating p38 MAPK pathway.Moreover,liquid chromatography-tandem mass spectrometry analysis identified 2208 proteins encapsulated in iMSC-lEVs,including 134 new-found proteins beyond current Vesiclepedia database.By bioinformatics and Western blot analyses,we showed that DUSP2 and DUSP3,the negative regulator of p38 phosphorylation,were enriched in iMSC-lEVs and could be transported to macrophages.Further,the immunomodulatory effect of iMSC-lEVs on macrophages was validated in explant tendon tissue from tendinopathy patients.Taken together,our results demonstrate that iMSC-lEVs could reduce inflammation in tendinopathy by regulating macrophage heterogeneity,which is mediated via the p38 MAPK pathway by delivery of DUSP2 and DUSP3,and might be a promising candidate for tendinopathy therapy.

Axonal regeneration and sprouting as a potential therapeutic target for nervous system disorders

Nervous system disorders are prevalent health issues that will only continue to increase in frequency as the population ages.Dying-back axonopathy is a hallmark of many neurologic diseases and leads to axonal disconnection from their targets,which in turn leads to functional impairment.During the course of many of neurologic diseases,axons can regenerate or sprout in an attempt to reconnect with the target and restore synapse function.In amyotrophic lateral sclerosis(ALS),distal motor axons retract from neuromuscular junctions early in the disease-course before significant motor neuron death.There is evidence of compensatory motor axon sprouting and reinnervation of neuromuscular junctions in ALS that is usually quickly overtaken by the disease course.Potential drugs that enhance compensatory sprouting and encourage reinnervation may slow symptom progression and retain muscle function for a longer period of time in ALS and in other diseases that exhibit dying-back axonopathy.There remain many outstanding questions as to the impact of distinct disease-causing mutations on axonal outgrowth and regeneration,especially in regards to motor neurons derived from patient induced pluripotent stem cells.Compartmentalized microfluidic chambers are powerful tools for studying the distal axons of human induced pluripotent stem cells-derived motor neurons,and have recently been used to demonstrate striking regeneration defects in human motor neurons harboring ALS disease-causing mutations.Modeling the human neuromuscular circuit with human induced pluripotent stem cells-derived motor neurons will be critical for developing drugs that enhance axonal regeneration,sprouting,and reinnervation of neuromuscular junctions.In this review we will discuss compensatory axonal sprouting as a potential therapeutic target for ALS,and the use of compartmentalized microfluidic devices to find drugs that enhance regeneration and axonal sprouting of motor axons.

Reciprocal effects of alpha-synuclein aggregation and lysosomal homeostasis in synucleinopathy models

Background Lysosomal dysfunction has been implicated in a number of neurodegenerative diseases such as Parkinson’s disease(PD).Various molecular,clinical and genetic studies have highlighted a central role of lysosomal pathways and proteins in the pathogenesis of PD.Within PD pathology the synaptic protein alpha-synuclein(αSyn)converts from a soluble monomer to oligomeric structures and insoluble amyloid fibrils.The aim of this study was to unravel the effect ofαSyn aggregates on lysosomal turnover,particularly focusing on lysosomal homeostasis and cathepsins.Since these enzymes have been shown to be directly involved in the lysosomal degradation ofαSyn,impairment of their enzymatic capacity has extensive consequences.Methods We used patient-derived induced pluripotent stem cells and a transgenic mouse model of PD to examine the effect of intracellularαSyn conformers on cell homeostasis and lysosomal function in dopaminergic(DA)neurons by biochemical analyses.Results We found impaired lysosomal trafficking of cathepsins in patient-derived DA neurons and mouse models withαSyn aggregation,resulting in reduced proteolytic activity of cathepsins in the lysosome.Using a farnesyltransferase inhibitor,which boosts hydrolase transport via activation of the SNARE protein ykt6,we enhanced the maturation and proteolytic activity of cathepsins and thereby decreasedαSyn protein levels.Conclusions Our findings demonstrate a strong interplay betweenαSyn aggregation pathways and function of lysosomal cathepsins.It appears thatαSyn directly interferes with the enzymatic function of cathepsins,which might lead to a vicious cycle of impairedαSyn degradation.

Alzheimer’s in a dish-induced pluripotent stem cell-based disease modeling

Background:Since the discovery of the induced pluripotent stem cell(iPSC)technique more than a decade ago,extensive progress has been made to develop clinically relevant cell culture systems.Alzheimer’s disease(AD)is the most common neurodegenerative disease,accounting for approximately two thirds of all cases of dementia.The massively increasing number of affected individuals explains the major interest of research in this disease as well as the strong need for better understanding of disease mechanisms.Main body:IPSC-derived neural cells have been widely used to recapitulating key aspects of AD.In this Review we highlight the progress made in studying AD pathophysiology and address the currently available techniques,such as specific differentiation techniques for AD-relevant cell types as well as 2D and 3D cultures.Finally,we critically discuss the key challenges and future directions of this field and how some of the major limitations of the iPSC technique may be overcome.Conclusion:Stem cell-based disease models have the potential to induce a paradigm shift in biomedical research.In particular,the combination of the iPSC technology with recent advances in gene editing or 3D cell cultures represents a breakthrough for in vitro disease modeling and provides a platform for a better understanding of disease mechanisms in human cells and the discovery of novel therapeutics.

Neural progenitor cells from human induced pluripotent stem cells generated less autogenous immune response

The breakthrough development of induced pluripotent stem cells(iPSCs)raises the prospect of patient-specific treatment for many diseases through the replacement of affected cells.However,whether iPSC-derived functional cell lineages generate a deleterious immune response upon auto-transplantation remains unclear.In this study,we differentiated five human iPSC lines from skin fibroblasts and urine cells into neural progenitor cells(NPCs)and analyzed their immunogenicity.Through co-culture with autogenous peripheral blood mononuclear cells(PBMCs),we showed that both somatic cells and iPSC-derived NPCs do not stimulate significant autogenous PBMC proliferation.However,a significant immune reaction was detected when these cells were co-cultured with allogenous PBMCs.Furthermore,no significant expression of perforin or granzyme B was detected following stimulation of autogenous immune effector cells(CD3+CD8 T cells,CD3+CD8+T cells or CD3 CD56+NK cells)by NPCs in both PBMC and T cell co-culture systems.These results suggest that human iPSC-derived NPCs may not initiate an immune response in autogenous transplants,and thus set a base for further preclinical evaluation of human iPSCs.