Neuroprotective effects of mesenchymal stromal cells in mouse models of Alzheimer's Disease: The Mediating role of gut microbes and their metabolites via the Microbiome-Gut-Brain axis.

The intricacy and multifaceted nature of Alzheimer's disease (AD) necessitate therapies that target multiple aspects of the disease. Mesenchymal stromal cells (MSCs) emerge as potential agents to mitigate AD symptoms; however, whether their therapeutic efficacy involves modulation of gut microbiota and the microbiome-gut-brain axis (MGBA) remains unexplored. In this study, we evaluated the effects of three distinct MSCs types-derived from the umbilical cord (UCMSC), dental pulp (SHED), and adipose tissue (ADSC)-in an APP/PS1 mouse model of AD. In comparison to saline control, MSCs administration resulted in a significant reduction of behavioral disturbances, amyloid plaques, and phosphorylated tau in the hippocampus and frontal cortex, accompanied by an increase in neuronal count and Nissl body density across AD-afflicted brain regions. Through 16S rRNA gene sequencing, we identified partial restoration of gut microbial balance in AD mice post-MSCs treatment, evidenced by the elevation of neuroprotective Akkermansia and reduction of the AD-associated Sphingomonas. To examine whether gut microbiota involved in MSCs efficacy in treating AD, SHED with better anti-inflammatory and gut microbiota recovery effects among three MSCs, and another AD model 5 × FAD mice with earlier and more pathological proteins in brain than APP/PS1, were selected for further studies. Antibiotic-mediated gut microbial inactivation attenuated MSCs efficacy in 5 × FAD mice, implicating the involvement of gut microbiota in the therapeutic mechanism. Functional analysis of altered gut microbiota and targeted bile acid metabolism profiling revealed a significant enhancement in bile acid variety following MSCs therapy. A chief bile acid constituent, taurocholic acid (TCA), was orally administered to AD mice and similarly abated AD symptoms. Nonetheless, the disruption of intestinal neuronal integrity with enterotoxin abrogated the ameliorative impact of both MSCs and TCA treatments. Collectively, our findings substantiate that MSCs confer therapeutic benefits in AD within a paradigm that primarily involves regulation of gut microbiota and their metabolites through the MGBA.

Comparative proteomics analysis of human stem cells from dental gingival and periodontal ligament.

Dental stem cells isolated from oral tissues have been shown to provide with high proliferation ability and multilineage differentiation potential. Gingival mesenchymal stem cells (GMSCs) and periodontal ligament stem cells (PDLSCs), kinds of dental stem cells, can be used as substitutes for tissue repair materials because of their similar regenerative functions. In this study, we aim to explore the similarities and differences between the protein profiles of GMSCs and PDLSCs through quantitative proteomics. A total of 2821 proteins were identified and retrieved, of which 271 were upregulated and 57 were downregulated in GMSCs compared to PDLSCs. Gene Ontology (GO) analysis demonstrated that the 328 differentially abundant proteins (DAPs) were involved in the regulation of gene expression, metabolism, and signal transduction in biological process, mainly distributed in organelles related to vesicle transport, and involved in the molecular function of binding protein. And Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the DAPs were committed to regulating the synthesis of proteasome and spliceosome. Real-time quantitative polymerase chain reaction (RT-qPCR) results showed that ARPC1B, PDAP1, and SEC61B can be used as special markers to distinguish GMSCs from PDLSCs. This research contributes to explaining the molecular mechanism and promoting the clinical application of tissue regeneration of GMSCs and PDLSCs.

Human gingival mesenchymal stem cells improve movement disorders and tyrosine hydroxylase neuronal damage in Parkinson disease rats.

BACKGROUND AIMS: Gingival mesenchymal stem cells (GMSCs) demonstrate high proliferation, trilineage differentiation and immunomodulatory properties. Parkinson disease (PD) is the second most common type of neurodegenerative disease. This study aimed to explore the effect and mechanism of GMSC-based therapy in 6-hydroxydopamine-induced PD rats. METHODS: RNA sequencing and quantitative proteomics technology was used to validate the neuroprotective role of GMSCs therapeutic in 6-Hydroxydopamine -induced PD model in vitro and in vivo. Western blotting, immunofluorescence and real-time quantitative PCR verified the molecular mechanism of GMSCs treatment. RESULTS: Intravenous injection of GMSCs improved rotation and forelimb misalignment behavior, enhanced the anti-apoptotic B-cell lymphoma 2/B-cell lymphoma 2-associated X axis, protected tyrosine hydroxylase neurons, decreased the activation of astrocytes and reduced the astrocyte marker glial fibrillary acidic protein and microglia marker ionized calcium-binding adaptor molecule 1 in the substantia nigra and striatum of PD rats. The authors found that GMSCs upregulated nerve regeneration-related molecules and inhibited metabolic disorders and the activation of signal transducer and activator of transcription 3. GMSCs showed a strong ability to protect neurons and reduce mitochondrial membrane potential damage and reactive oxygen species accumulation. The safety of GMSC transplantation was confirmed by the lack of tumor formation following subcutaneous transplantation into nude mice for up to 8 weeks. CONCLUSIONS: The authors' research helps to explain the mechanism of GMSC-based therapeutic strategies and promote potential clinical application in Parkinson disease.

Metformin pre-treatment of stem cells from human exfoliated deciduous teeth promotes migration and angiogenesis of human umbilical vein endothelial cells for tissue engineering.

BACKGROUND AIMS: Stem cells from human exfoliated deciduous teeth (SHED) play a significant role in tissue engineering and regenerative medicine. Angiogenesis is crucial in tissue regeneration and a primary target of regenerative medicine. As a first-line anti-diabetic drug, metformin demonstrates numerous valuable impacts on stem cells. This study aimed to explore metformin's impact and mechanism of action on SHED-mediated angiogenesis. METHODS: First, cell proliferation; flow cytometry; osteogenic, adipogenic and chondrogenic induction; and proteomics analyses were conducted to explore the role of metformin in SHED. Subsequently, migration and tube formation assays were used to evaluate chemotaxis and angiogenesis enhancement by SHED pre-treated with metformin under co-culture conditions in vitro, and relative messenger RNA expression levels were determined by quantitative reverse transcription polymerase chain reaction. Finally, nude mice were used for in vivo tube formation assay, and sections were analyzed through immunohistochemistry staining with anti-human CD31 antibody. RESULTS: Metformin significantly promoted SHED proliferation as well as osteogenic, adipogenic and chondrogenic differentiation. Proteomics showed that metformin significantly upregulated 124 differentially abundant proteins involved in intracellular processes, including various proteins involved in cell migration and angiogenesis, such as MAPK1. The co-culture system demonstrated that SHED pre-treated with metformin significantly improved the migration and angiogenesis of human umbilical vein endothelial cells. In addition, SHED pre-treated with metformin possessed greater ability to promote angiogenesis in vivo. CONCLUSIONS: In summary, the authors' findings illustrate metformin's mechanism of action on SHED and confirm that SHED pre-treated with metformin exhibits a strong capacity for promoting angiogenesis. This helps in promoting the application of dental pulp-derived stem cells pre-treated with metformin in regeneration engineering.

Hydrogel supplemented with human platelet lysate enhances multi-lineage differentiation of mesenchymal stem cells.

Stem cells from human exfoliated deciduous teeth (SHED) can be used as a potential clinical material. But the use of xenogeneic ingredients will increase the risk of zoonotic disease transmission. Human platelet lysate (HPL) is a potential surrogate and used in human cell expansion with reliability in clinical applications. In this study, we synthesized chitosan/gelatin/gellan gum hydrogel supplemented with HPL and investigated the effect of 3D culture for SHED. TMT-tagged proteomics was used to decipher the secretome protein profiles of SHEDs and a total of 3209 proteins were identified, of which 23 were up-regulated and 192 were down-regulated. The results showed that hydrogel supplemented with HPL promoted SHED proliferation. After induction, the hydrogel coating contributed to osteogenic differentiation, adipogenic differentiation and differentiation into neural-like cells of SHED. SHED encapsulated in a hydrogel promotes migration and angiogenesis of HUVEC. In conclusion, our research found that hydrogel supplemented with HPL can be used as a method for SHED in standardized production and can contribute to the clinical application of SHED in cell therapy.

Chitosan Hydrogel Supplemented with Metformin Promotes Neuron-like Cell Differentiation of Gingival Mesenchymal Stem Cells.

Human gingival mesenchymal stem cells (GMSCs) are derived from migratory neural crest stem cells and have the potential to differentiate into neurons. Metformin can inhibit stem-cell aging and promotes the regeneration and development of neurons. In this study, we investigated the potential of metformin as an enhancer on neuronal differentiation of GMSCs in the growth environment of chitosan hydrogel. The crosslinked chitosan/ß-glycerophosphate hydrogel can form a perforated microporous structure that is suitable for cell growth and channels to transport water and macromolecules. GMSCs have powerful osteogenic, adipogenic and chondrogenic abilities in the induction medium supplemented with metformin. After induction in an induction medium supplemented with metformin, Western blot and immunofluorescence results showed that GMSCs differentiated into neuron-like cells with a significantly enhanced expression of neuro-related markers, including Nestin (NES) and ß-Tubulin (TUJ1). Proteomics was used to construct protein profiles in neural differentiation, and the results showed that chitosan hydrogels containing metformin promoted the upregulation of neural regeneration-related proteins, including ATP5F1, ATP5J, NADH dehydrogenase (ubiquinone) Fe-S protein 3 (NDUFS3), and Glutamate Dehydrogenase 1 (GLUD1). Our results help to promote the clinical application of stem-cell neural regeneration.

Partial-film mulch returns the same gains in yield and water use efficiency as full-film mulch with reduced cost and lower pollution: a meta-analysis.

BACKGROUND: Plastic film mulch is widely used to improve crop yield and water use efficiency (WUE, yield per unit evapotranspiration) in semi-arid regions. It is commonly applied as partial-film mulch (PM: at least 50% soil cover) or full-film mulch (FM: complete soil cover). The PM has lower economic and environmental cost; hence it would be a superior technology provided it delivers similar gains in yield and WUE in relation to FM. RESULTS: To solve contradictory results from individual studies, we compared FM and PM in a meta-analysis of 100 studies with 1881 comparisons (685 for wheat; 1196 for maize). Compared with bare ground, FM and PM both increased yield of wheat (20-26%) and maize (37-52%), and WUE of wheat (16-20%) and maize (38-48%), with statistically undistinguishable differences between PM and FM. The increases in crop yield and WUE were stronger at elevation > 1000 m, with annual precipitation<400 mm, and on loess soil, especially for maize. CONCLUSIONS: We concluded that partial-film mulch could replace full-film mulch to return similar yield and WUE improvement, with reduced cost and environmental pollution. © 2021 Society of Chemical Industry.

Effects of triclosan exposure on stem cells from human exfoliated deciduous teeth (SHED) fate.

Triclosan (TCS), a widely used broad-spectrum antibacterial agent and preservative, is commonly found in products and environments. Widespread human exposure to TCS has drawn increasing attention from researchers concerning its toxicological effect. However, minimal studies have focused on the impact of TCS exposure on human stem cells. Therefore, the aim of the present study was to evaluate the effects of TCS exposure on stem cells from human exfoliated deciduous teeth (SHED) and its molecular mechanisms. A series of experimental methods were conducted to assess cell viability, morphology, proliferation, differentiation, senescence, apoptosis, mitochondrial function, and oxidative stress after SHED exposure to TCS. Furthermore, transcriptome analysis was applied to investigate the response of SHED to different concentrations of TCS exposure and to explore the molecular mechanisms. We demonstrated that TCS has a dose-dependent proliferation and differentiation inhibition of SHED, while promoting cellular senescence, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and oxidative stress, as well as significantly induces apoptosis and autophagy flux inhibition at high concentrations. Interestingly, no significant morphological changes in SHED were observed after TCS exposure. Transcriptome analysis of normal and TCS-induced SHED suggested that SHED may use different strategies to counteract stress from different concentrations of TCS and showed significant differences. We discovered that TCS mediates cellular injury of SHED by enhancing the expression of PTEN, thereby inhibiting the phosphorylation levels of PI3K and AKT as well as mTOR expression. Collectively, our findings provide a new understanding of the toxic effects of TCS on human stem cell fate, which is important for determining the risk posed by TCS to human health.

Stem cells from human exfoliated deciduous teeth relieves Alzheimer's disease symptoms in SAMP8 mice by up-regulating the PPARγ pathway.

The pathology of Alzheimer's disease (AD) is complex and heterogeneous, and there are currently no drugs that can stop its progression. The failure of traditional chemical small-molecule drug development showed the weakness of single target and made researchers look to cell therapy with multiple regulatory effects. Stem cells from human exfoliated deciduous teeth (SHED) are a kind of neural crest-derived mesenchymal stem cells which have broad prospects in the treatment of neurodegenerative diseases. In this study, we demonstrated the therapeutic effects of SHED in AD mice, including behavioral improvement, neuronal protection, and alleviation of neuroinflammation. Tracking experiments on SHED showed that some of the transplanted cells could enter the brain. To elucidate the role played by the majority of cells transplanted into veins, blood proteomic assays were performed. Data are available via ProteomeXchange with identifier PXD030313. Among the altered proteins, the PPAR pathway related to energy metabolism was considered to be an important signaling pathway involved in regulation through gene ontology analysis and pathway analysis. Western blot showed that the transplantation of SHED improved the glucose metabolism in AD mice by increasing the PPARγ signaling pathway. These results suggested that SHED have a potential in relieving AD pathological symptoms and improving behavioral cognition. The therapeutic mechanism of SHED is related to up-regulating PPARγ signaling pathway and reducing neuronal damage.

Characteristics, Classification, and Application of Stem Cells Derived from Human Teeth.

Since mesenchymal stem cells derived from human teeth are characterized as having the properties of excellent proliferation, multilineage differentiation, and immune regulation. Dental stem cells exhibit fibroblast-like microscopic appearance and express mesenchymal markers, embryonic markers, and vascular markers but do not express hematopoietic markers. Dental stem cells are a mixed population with different sensitive markers, characteristics, and therapeutic effects. Single or combined surface markers are not only helpful for understanding the subpopulation of mixed stem cell populations according to cell function but also for improving the stable treatment effect of dental stem cells. Focusing on the discovery and characterization of stem cells isolated from human teeth over the past 20 years, this review outlines the effect of marker sorting on cell proliferation and differentiation ability and the assessment of the clinical application potential. Classified dental stem cells from markers and functional molecules can solve the problem of heterogeneity and ensure the efficacy of cell therapy strategies including dentistry, neurologic diseases, bone repair, and tissue engineering.

Proteomic profile of human dental follicle stem cells and apical papilla stem cells.

Dental stem cells have great potential in clinical practice as an adult mesenchymal stem cell, such as dental follicle and the apical papilla, have strong proliferation and differentiation characteristics. The developmental relevance and discrimination of them in the niche is not clear, which limits their application scenarios. The aim of this study was to investigate the intrinsical differences in cellular contents of DFSCs and SCAP by Tandem mass tag (TMT) labeling quantitative proteomics. Cell lysates were labeled and tracked by the combined use of TMT and LC-MS/MS. A total of 1622 proteins were detected, of which 421 were different and 12 were significantly up-regulated and 4 were significantly down-regulated. The results of proteomics support the application of stem cells in the treatment of neurodegenerative diseases such as Huntington's disease, Alzheimer's disease, Parkinson's disease and so on. The difference is related to cell proliferation and protection of neurons from inflammation and autophagy damage. Highly expressed proteins predict the special ability of DFSCs to stably proliferate and differentiate through CD13, MARCKS, and PAST1. The strong immune stability of SCAP is supported by NPC1.This study expands our understanding on the molecular mechanisms of tooth development and regeneration, and provide basic support for dental stem cells in clinical applications such as neurological and immune diseases.

The potential therapy with dental tissue-derived mesenchymal stem cells in Parkinson's disease.

Parkinson's disease (PD), the second most common neurodegenerative disease worldwide, is caused by the loss of dopaminergic (DAergic) neurons in the substantia nigra resulting in a series of motor or non-motor disorders. Current treatment methods are unable to stop the progression of PD and may bring certain side effects. Cell replacement therapy has brought new hope for the treatment of PD. Recently, human dental tissue-derived mesenchymal stem cells have received extensive attention. Currently, dental pulp stem cells (DPSCs) and stem cells from human exfoliated deciduous teeth (SHED) are considered to have strong potential for the treatment of these neurodegenerative diseases. These cells are considered to be ideal cell sources for the treatment of PD on account of their unique characteristics, such as neural crest origin, immune rejection, and lack of ethical issues. In this review, we briefly describe the research investigating cell therapy for PD and discuss the application and progress of DPSCs and SHED in the treatment of PD. This review offers significant and comprehensive guidance for further clinical research on PD.

Proteomic profile of human stem cells from dental pulp and periodontal ligament.

Background The study of molecular profiling of dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) contributes to understanding the high proliferation ability and multi-lineage differentiation potential. Objectives The aim of the study was to compare the protein abundance and specific markers of DPSCs and PDLSCs by protein profiles. Material and methods The DPSCs and PDLSCs extracted from the same tooth were lysed with 3 biological replicates and the protein was collected. Two-dimensional electrophoresis technology and TMT proteomics were used to separate and identify proteins. The data are available via ProteomeXchange with identifier PXD021997. The RT-qPCR detection of mRNA expression revealed a special marker for distinguishing two kinds of dental stem cells. Results Compared with PDLSCs, 962 differential proteins (DAPs) were up-regulated, and 127 were down-regulated in DPSCs. In the up-regulated DAPs, two high-scoring sub-networks were detected for neural-related molecules, which encode cell vesicle transport and mitochondrial energy transfer to regulate cell proliferation and secretion factors. A large number of cell adhesion molecules were distinguished among the highly expressed molecules of PDLSCs, supporting that stem cells provide cell attachment functions. It was interpreted ENPL, HS90A and HS90B were highly expressed in DPSCs, while CKB was highly abundant in PDLSCs. Another cell group confirmed that these molecules can be used as special biomarkers to identify and distinguish between DPSCs and PDLSCs. Conclusions This study can promote the basic research and clinical application of dental stem cells. Significance The high-throughput protein profiles were tested by combining two-dimensional gel proteomics and TMT-based proteomics. The proteomics of DPSCs and PDLSCs without individual difference demonstrated an accurate and comprehensive molecular expression profiles and interpretation of neural application potential, this study promotes the basic research of dental stem cells and clinical application.

Stem Cells from Human Exfoliated Deciduous teeth Promote Hair Regeneration in Mouse.

Stem cells in different types may interact with each other to maintain homeostasis or growth and the interactions are complicated and extensive. There is increasing evidence that mesenchymal-epithelial interactions in early morphogenesis stages of both tooth and hair follicles show many similarities. In order to explore whether stem cells from one tissue could interact with cells from another tissue, a series of experiments were carried out. Here we successfully extracted and identified stem cells from human exfoliated deciduous teeth (SHED) of 8-12 years old kids, and then found that SHED could promote hair regeneration in a mouse model. In vitro, SHED shortened the hair regeneration cycle and promoted the proliferation and aggregation of dermal cells. In vivo, when SHED and skin cells of C57 mice were subcutaneously co-transplanted to nude mice, more hair was formed than skin cells without SHED. To further explore the molecular mechanism, epidermal and dermal cells were freshly extracted and co-cultured with SHED. Then several signaling molecules in hair follicle regeneration were detected and we found that the expression of Sonic Hedgehog (Shh) and Glioma-associated oncogene 1 (Gli1) was up-regulated. It seems that SHED may boost the prosperity of hairs by increase Shh/Gli1 pathway, which brings new perspectives in tissue engineering and damaged tissue repairing.

Calreticulin as a special marker to distinguish dental pulp stem cells from gingival mesenchymal stem cells.

The construction of protein abundance profiles helps to interpret the clinical applications of stem cells. Dental pulp stem cells (DPSCs) and gingival mesenchymal stem cells (GMSCs) can be isolated from teeth and used as a highly convenient clinical potential material. Here, we aimed to explore commonalities and differences of DPSCs and GMSCs at the protein level. TMT-based quantitative proteomics and two-dimensional gel electrophoresis technology were used in combination to describe the protein profile of DPSCs and GMSCs extracted from the same donor. A total of 2821 proteins were identified by LC-MS/MS, of which 248 differentially abundant proteins (DAPs) were highly expressed in GMSCs while 782 proteins were highly expressed in DPSCs. The biological functions and molecular pathways of DAPs were annotated with GO enrichment and KEGG analysis. The relationship between molecular abundance and cell characteristics including source, proliferation, angiogenesis and inflammation were connected by WGCNA. Special markers, including Calreticulin (CALR), Annexin A5 (ANXA5) and Rho GDP dissociation inhibitor alpha (GDIR1), were proposed to distinguish DPSCs from GMSCs. Our results provide a molecular basis for in-depth understanding of the protein composition and special functions of dental stem cells, and promote the potential clinical application.