Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a p...Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a promising treatment for Parkinson’s disease.However,transplanted cells can be injured by mechanical damage during handling and by changes in the transplantation niche.Here,we developed a one-step biomanufacturing platform that uses small-aperture gelatin microcarriers to produce beads carrying midbrain dopaminergic progenitor cells.These beads allow midbrain dopaminergic progenitor cell differentiation and cryopreservation without digestion,effectively maintaining axonal integrity in vitro.Importantly,midbrain dopaminergic progenitor cell bead grafts showed increased survival and only mild immunoreactivity in vivo compared with suspended midbrain dopaminergic progenitor cell grafts.Overall,our findings show that these midbrain dopaminergic progenitor cell beads enhance the effectiveness of neuronal cell transplantation.展开更多
PTEN-induced putative kinase 1(PINK1),a mitochondrial kinase that phosphorylates Parkin and other proteins,plays a crucial role in mitophagy and protection against neurodegeneration.Mutations in PINK1 and Parkin can l...PTEN-induced putative kinase 1(PINK1),a mitochondrial kinase that phosphorylates Parkin and other proteins,plays a crucial role in mitophagy and protection against neurodegeneration.Mutations in PINK1 and Parkin can lead to loss of function and early onset Parkinson's disease.However,there is a lack of strong in vivo evidence in rodent models to support the theory that loss of PINK1 affects mitophagy and induces neurodegeneration.Additionally,PINK1 knockout pigs(Sus scrofa)do not appear to exhibit neurodegeneration.In our recent work involving non-human primates,we found that PINK1 is selectively expressed in primate brains,while absent in rodent brains.To extend this to other species,we used multiple antibodies to examine the expression of PINK1 in pig tissues.In contrast to tissues from cynomolgus monkeys(Macaca fascicularis),our data did not convincingly demonstrate detectable PINK1expression in pig tissues.Knockdown of PINK1 in cultured pig cells did not result in altered Parkin and BAD phosphorylation,as observed in cultured monkey cells.A comparison of monkey and pig striatum revealed more PINK1-phosphorylated substrates in the monkey brain.Consistently,PINK1 knockout in pigs did not lead to obvious changes in the phosphorylation of Parkin and BAD.These findings provide new evidence that PINK1expression is specific to primates,underscoring the importance of non-human primates in investigating PINK1function and pathology related to PINK1 deficiency.展开更多
Exosomes,a type of extracellular vesicles(EVs),were first discovered in sheep reticulocytes in 1983[1],and after four years,the name‘exosome’was officially given to them.A variety of cells secrete exosomes under bot...Exosomes,a type of extracellular vesicles(EVs),were first discovered in sheep reticulocytes in 1983[1],and after four years,the name‘exosome’was officially given to them.A variety of cells secrete exosomes under both normal and pathological conditions.Exosomes are mainly products of themultivesicular body formed by intracellular lysosomal invagi nation,and released into the extracellular space by fusion of the outer membrane of the multivesicular body with the cell membrane.展开更多
Platelet transfusion is one of the most reliable strategies to cure patients suffering from thrombocytopenia or platelet dysfunction.With the increasing demand for transfusion,however,there is an undersupply of donors...Platelet transfusion is one of the most reliable strategies to cure patients suffering from thrombocytopenia or platelet dysfunction.With the increasing demand for transfusion,however,there is an undersupply of donors to provide the platelet source.Thus,scientists have sought to design methods for deriving clinical-scale platelets ex vivo.Although there has been considerable success ex vivo in the generation of transformative platelets produced by human stem cells(SCs),the platelet yields achieved using these strategies have not been adequate for clinical application.In this review,we provide an overview of the developmental process of megakaryocytes and the production of platelets in vivo and ex vivo,recapitulate the key advances in the production of SC-derived platelets using several SC sources,and discuss some strategies that apply three-dimensional bioreactor devices and biochemical factors synergistically to improve the generation of large-scale platelets for use in future biomedical and clinical settings.展开更多
Obesity,which can arise from genetic or environmental factors,has been shown to cause serious damages to the reproductive system.The ovary,as one of the primary regulators of female fertility,is a complex organ compri...Obesity,which can arise from genetic or environmental factors,has been shown to cause serious damages to the reproductive system.The ovary,as one of the primary regulators of female fertility,is a complex organ comprised of heterogeneous cell types that work together to maintain a normal ovarian microenvironment(OME).Despite its importance,the effect of obesity on the entire ovary remains poorly documented.In this study,we performed ovary single-cell and nanoscale spatial RNA sequencing to investigate how the OME changed under different kinds of obesity,including high-fat diet(HFD)induced obesity and Leptin ablation induced obesity(OB).Our results demonstrate that OB,but not HFD,dramatically altered the proportion of ovarian granulosa cells,theca-interstitial cells,luteal cells,and endothelial cells.Furthermore,based on the spatial dynamics of follicular development,we defined four subpopulations of granulosa cell and found that obesity drastically disrupted the differentiation of mural granulosa cells from small to large antral follicles.Functionally,HFD enhanced follicle-stimulating hormone(FSH)sensitivity and hormone conversion,while OB caused decreased sensitivity,inadequate steroid hormone conversion,and impaired follicular development.These differences can be explained by the differential expression pattern of the transcription factor Foxo1.Overall,our study provides a powerful and high-resolution resource for profiling obesity-induced OME and offers insights into the diverse effects of obesity on female reproductive disorders.展开更多
Background: Mastitis, an infection caused by Gram-positive bacteria, produces udder inflammation and oxidative injury in milk-producing mammals. Toll-like receptor 2(TLR2) is important for host recognition of invading...Background: Mastitis, an infection caused by Gram-positive bacteria, produces udder inflammation and oxidative injury in milk-producing mammals. Toll-like receptor 2(TLR2) is important for host recognition of invading Grampositive microbes. Over-expression of TLR2 in transgenic dairy goats is a useful model for studying various aspects of infection with Gram-positive bacteria, in vivo.Methods: We over-expressed TLR2 in transgenic dairy goats. Pam3CSK4, a component of Gram-positive bacteria,triggered the TLR2 signal pathway by stimulating the monocytes-macrophages from the TLR2-positive transgenic goats, and induced over-expression of activator protein-1(AP-1), phosphatidylinositol 3-kinase(PI3K) and transcription factor nuclear factor kappa B(NF-κB) and inflammation factors downstream of the signal pathway.Results: Compared with wild-type controls, measurements of various oxidative stress-related molecules showed that TLR2, when over-expressed in transgenic goat monocytes-macrophages, resulted in weak lipid damage, high level expression of anti-oxidative stress proteins, and significantly increased m RNA levels of transcription factor NF-E2-related factor-2(Nrf2) and the downstream gene, heme oxygenase-1(HO-1). When Pam3CSK4 was used to stimulate ear tissue in vivo the HO-1 protein of the transgenic goats had a relatively high expression level.Conclusions: The results indicate that the oxidative injury in goats over-expressing TLR2 was reduced following Pam3CSK4 stimulation. The underlying mechanism for this reduction was increased expression of the anti-oxidation gene HO-1 by activation of the Nrf2 signal pathway.展开更多
Sertoli cells play essential roles in the process of spermatogenesis such as maintaining the integrity of blood-testis barrier(BTB),engulfing sperm resid ual cytoplasm and secreting critical cytokines.PA1 has been rep...Sertoli cells play essential roles in the process of spermatogenesis such as maintaining the integrity of blood-testis barrier(BTB),engulfing sperm resid ual cytoplasm and secreting critical cytokines.PA1 has been reported to be a unique component of histone lysine methylation modification complex MLL3/4,regulating gene transcription by histone 3 lysine 4 methylation(H3K4me).However,it is unknown whether PA1 is involved in the epigenetic regulation in male reproductive system.展开更多
The testis is pivotal for male reproduction,and its progressive functional decline in aging is associated with infertility.However,the regulatory mechanism underlying primate testicular aging remains largely elusive.H...The testis is pivotal for male reproduction,and its progressive functional decline in aging is associated with infertility.However,the regulatory mechanism underlying primate testicular aging remains largely elusive.Here,we resolve the aging-related cellular and molecular alterations of primate testicular aging by establishing a single-nucleus transcriptomic atlas.Gene-expression patterns along the spermatogenesis trajectory revealed molecular programs associated with attrition of spermatogonial stem cell reservoir,disturbed meiosis and impaired spermiogenesis along the sequential continuum.Remarkably,Sertoli cell was identified as the cell type most susceptible to aging,given its deeply perturbed age-associated transcriptional profiles.Concomitantly,downregulation of the transcription factor Wilms'Tumor 1(WTi),essential for Sertoli cell homeostasis,was associated with accelerated cellular senescence,disrupted tight junctions,and a compromised cell identity signature,which altogether may help create a hostile microenvironment for spermatogenesis.Collectively,our study depicts in-depth transcriptomic traits of non-human primate(NHP)testicular aging at single-cell resolution,providing potential diagnostic biomarkers and targets for therapeutic interventions against testicular aging and age-related male reproductive diseases.展开更多
Hereditary hearing loss(HHL),a genetic disorder that impairs auditory function,significantly affects quality of life and incurs substantial economic losses for society.To investigate the underlying causes of HHL and e...Hereditary hearing loss(HHL),a genetic disorder that impairs auditory function,significantly affects quality of life and incurs substantial economic losses for society.To investigate the underlying causes of HHL and evaluate therapeutic outcomes,appropriate animal models are necessary.Pigs have been extensively used as valuable large animal models in biomedical research.In this review,we highlight the advantages of pig models in terms of ear anatomy,inner ear morphology,and electrophysiological characteristics,as well as recent advancements in the development of distinct genetically modified porcine models of hearing loss.Additionally,we discuss the prospects,challenges,and recommendations regarding the use pig models in HHL research.Overall,this review provides insights and perspectives for future studies on HHL using porcine models.展开更多
Cullin-RING E3 ubiquitin ligases(CRLs),the largest family of multi-subunit E3 ubiquitin ligases in eukaryotic cells,represent core cellular machinery for executing protein degradation and maintaining proteostasis.Here...Cullin-RING E3 ubiquitin ligases(CRLs),the largest family of multi-subunit E3 ubiquitin ligases in eukaryotic cells,represent core cellular machinery for executing protein degradation and maintaining proteostasis.Here,we asked what roles Cullin proteins play in human mesenchymal stem cell(hMSC)homeostasis and senescence.To this end,we conducted a comparative aging phenotype analysis by individually knocking down Cullin members in three senescence models:replicative senescent hMSCs,Hutchinson-Gilford Progeria Syndrome hMSCs,and Werner syndrome hMSCs.Among all family members,we found that CUL2 deficiency rendered hMSCs the most susceptible to senescence.To investigate CUL2-specific underlying mechanisms,we then applied CRISPR/Cas9-mediated gene editing technology to generate CUL2-deficient human embryonic stem cells(hESCs).When we differentiated these into h MSCs,we found that CUL2 deletion markedly accelerates hMSC senescence.Importantly,we identified that CUL2 targets and promotes ubiquitin proteasome-mediated degradation of TSPYL2(a known negative regulator of proliferation)through the substrate receptor protein APPBP2,which in turn downregulates one of the canonical aging marker-P21^(waf1/cip1),and thereby delays senescence.Our work provides important insights into how CRL2^(APPBP2)-mediated TSPYL2 degradation counteracts hMSC senescence,providing a molecular basis for directing intervention strategies against aging and aging-related diseases.展开更多
Mechanical force is crucial in the whole process of embryonic development.However,the role of trophoblast mechanics during embryo implantation has rarely been studied.In this study,we constructed a model to explore th...Mechanical force is crucial in the whole process of embryonic development.However,the role of trophoblast mechanics during embryo implantation has rarely been studied.In this study,we constructed a model to explore the effect of stiffness changes in mouse trophoblast stem cells(mTSCs)on implantation:microcarrier was prepared by sodium alginate using a droplet microfluidics system,and mTSCs were attached to the microcarrier surface with laminin modifications,called T(micro).Compared with the spheroid,formed by the self-assembly of mTSCs(T(sph)),we could regulate the stiffness of the microcarrier,making the Young’s modulus of mTSCs(367.70±79.81 Pa)similar to that of the blastocyst trophoblast ectoderm(432.49±151.90 Pa).Moreover,T(micro)contributes to improve the adhesion rate,expansion area and invasion depth of mTSCs.Further,T(micro)was highly expressed in tissue migration-related genes due to the activation of the Rho-associated coiled-coil containing protein kinase(ROCK)pathway at relatively similar modulus of trophoblast.Overall,our study explores the embryo implantation process with a new perspective,and provides theoretical support for understanding the effect of mechanics on embryo implantation.展开更多
Blastocyst complementation by pluripotent stem cell(PSC)injection is believed to be the most promising method to generate xenogeneic organs.However,ethical issues prevent the study of human chimeras in the late embryo...Blastocyst complementation by pluripotent stem cell(PSC)injection is believed to be the most promising method to generate xenogeneic organs.However,ethical issues prevent the study of human chimeras in the late embryonic stage of development.Primate embryonic stem cells(ESCs),which have similar pluripotency to human ESCs,are a good model for studying interspecies chimerism and organ generation.However,whether primate ESCs can be used in xenogenous grafts remains unclear.In this study,we evaluated the chimeric ability of cynomolgus monkey(Macaca fascicularis)ESCs(cmESCs)in pigs,which are excellent hosts because of their many similarities to humans.We report an optimized culture medium that enhanced the anti-apoptotic ability of cmESCs and improved the development of chimeric embryos,in which domesticated cmESCs(D-ESCs)injected into pig blastocysts differentiated into cells of all three germ layers.In addition,we obtained two neonatal interspecies chimeras,in which we observed tissue-specific D-ESC differentiation.Taken together,the results demonstrate the capability of D-ESCs to integrate and differentiate into functional cells in a porcine model,with a chimeric ratio of 0.001-0.0001 in different neonate tissues.We believe this work will facilitate future developments in xenogeneic organogenesis,bringing us one step closer to producing tissue-specific functional cells and organs in a large animal model through interspecies blastocyst complementation.展开更多
RAP1 is a well-known telomere-binding protein, but its functions in human stem cells have remained unclea匚 Here we generated RAP1 -deficient human embryonic stem cells (hESCs) by using CRISPR/Cas9 technique and obtai...RAP1 is a well-known telomere-binding protein, but its functions in human stem cells have remained unclea匚 Here we generated RAP1 -deficient human embryonic stem cells (hESCs) by using CRISPR/Cas9 technique and obtained RAP1-deficient human mesenchymal stem cells (hMSCs) and neural stem cells (hNSCs) via directed differentiation. In both hMSCs and hNSCs, RAP1 not only negatively regulated telomere length but also acted as a transcriptional regulator of RELN by tuning the methylation status of its gene promoter. RAP1 deficiency enhanced self-renewal and delayed senescence in hMSCs, but not in hNSCs, suggesting complicated lineage-specific effects of RAP1 in adult stem cells.Altogether, these results demonstrate for the first time that RAP1 plays both telomeric and nontelomeric roles in regulating human stem cell homeostasis.展开更多
Pluripotent stem cells(PSCs) are cells that can differentiate into any type of cells in the body, therefore have valuable promise in regenerative medicine of cell replacement therapies and tissue/organ engineering. PS...Pluripotent stem cells(PSCs) are cells that can differentiate into any type of cells in the body, therefore have valuable promise in regenerative medicine of cell replacement therapies and tissue/organ engineering. PSCs can be derived either from early embryos or directly from somatic cells by epigenetic reprogramming that result in customized cells from patients. Here we summarize the methods of deriving PSCs, the various types of PSCs generated with different status, and their versatile applications in both clinical and embryonic development studies. We also discuss an intriguing potential application of PSCs in constructing tissues/organs in large animals by interspecies chimerism. All these emerging findings are likely to contribute to the breakthroughs in biological research and the prosperous prospects of regenerative medicine.展开更多
The molecular mechanisms underpinning temperature-dependent sex determination(TSD)in reptiles have attracted great biological interest for many years.However,which genetic factors are essential for TSD remain elusive,...The molecular mechanisms underpinning temperature-dependent sex determination(TSD)in reptiles have attracted great biological interest for many years.However,which genetic factors are essential for TSD remain elusive,especially regarding female sex determination.Cytochrome P450 family 19 subfamily A member 1(Cyp19a1)encodes the endoplasmic reticulum enzyme aromatase,which participates in the catalytic conversion of androgens to estrogens,and is implicated in sexual differentiation in many species.However,whether Cyp19a1 plays a critical role in determining gonadal sexual fate in TSD species remains to be elucidated.In the current study,Cyp19a1 exhibited a temperature-dependent and sexually dimorphic expression pattern,preceding gonadal sex differentiation in a TSD turtle species(Mauremys reevesii).Sexual phenotype of the turtles was successfully reversed by aromatase inhibitor treatment at the female-producing temperature(FPT).Furthermore,exogenous estradiol(E2)treatment led to complete male-to-female sex reversal at the male-producing temperature(MPT),accompanied by rapid up-regulation of Cyp19a1.Thus,Cyp19a1 appears to be essential for female sex determination in M.reevesii,suggesting a vital role in the female TSD pathway.展开更多
Dear Editor,Genome-scale screening is a powerful method used to explore phenotypes that are of interest,and numerous screening systems have been built for functional sites identification.Classical genetic screening in...Dear Editor,Genome-scale screening is a powerful method used to explore phenotypes that are of interest,and numerous screening systems have been built for functional sites identification.Classical genetic screening in eukaryotes has been performed using chemical mutagens(Chen et al.,2000),transposon mediated gene trapping(Dupuy et al.,2005),and CRISPR-Cas9 system(Wang et al.,2014).展开更多
Dear Editor,Stem cells,including pluripotent stem cells and adult stem cells,possess the remarkable capability of being able to selfrenew while at the same time having potential to differentiate into different cell li...Dear Editor,Stem cells,including pluripotent stem cells and adult stem cells,possess the remarkable capability of being able to selfrenew while at the same time having potential to differentiate into different cell lineages and functionally distinct cell types.Human embryonic stem cells(hESCs)can differentiate into all adult stem cell types,including human mesenchymal stem cells(hMSCs)and human neural stem cells(hNSCs),but can also give rise to all terminally differentiated cell types(Wang et al.,2021a).Through the continuous replenishment of differentiated cells,stem cells support tissue homeostasis and respond to tissue injuries.Given the promising applications of stem cells in cell therapy and regenerative medicine,insights into molecular events underlying stem cell maintenance,self-renewal ability and pluripotency,continue to garner strong interest(Shan et al.,2021).Although metabolic pathways have been implicated in the reciprocal regulations of stem cell self-renewal and differentiation as well as organ homeostatic maintenance(Garcia-Prat et al.,2017),central aspects of how metabolic requirements differ and are regulated across the various types of human stem cells in our body remain enigmatic.展开更多
Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders,the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown.Here,we report that the expression of ...Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders,the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown.Here,we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem celis(hMSCs).Genetic inactivation of 4E-BP1 in hMSCs compromises mitochondrial respiration,increases mitochondrial reactive oxygen species(Ros)production,and accelerates cellular senescence.Mechanistically,the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes,especially several key subunits of complex III including UQCRC2.Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs.These findings together demonstrate that 4E-BP1 functions as a geroprotector to mitigate human stem cell senescence and maintain mitochondrial homeostasis,particularly for the mitochondrial respiration complex Il,thus providing a new potential target to counteract human stem cell senescence.展开更多
Multiple sclerosis(MS) is an autoimmune disease of the central nervous system(CNS), with focal T lymphocytic infiltration and damage of myelin and axons. The underlying mechanism of pathogenesis remains unclear and th...Multiple sclerosis(MS) is an autoimmune disease of the central nervous system(CNS), with focal T lymphocytic infiltration and damage of myelin and axons. The underlying mechanism of pathogenesis remains unclear and there are currently no effective treatments. The development of neural stem cell(NSC) transplantation provides a promising strategy to treat neurodegenerative disease. However, the limited availability of NSCs prevents their application in neural disease therapy. In this study, we generated NSCs from induced pluripotent stem cells(iPSCs) and transplanted these cells into mice with experimental autoimmune encephalomyelitis(EAE), a model of MS. The results showed that transplantation of iPSC-derived NSCs dramatically reduced T cell infiltration and ameliorated white matter damage in the treated EAE mice. Correspondingly, the disease symptom score was greatly decreased, and motor ability was dramatically rescued in the iPSC-NSC-treated EAE mice, indicating the effectiveness of using iPSC-NSCs to treat MS. Our study provides pre-clinical evidence to support the feasibility of treating MS by transplantation of iPSC-derived NSCs.展开更多
基金supported by the National Key Research and Development Program of China,Nos.2017YFE0122900(to BH),2019YFA0110800(to WL),2019YFA0903802(to YW),2021YFA1101604(to LW),2018YFA0108502(to LF),and 2020YFA0804003(to JW)the National Natural Science Foundation of China,Nos.31621004(to WL,BH)and 31970821(to YW)+1 种基金CAS Project for Young Scientists in Basic Research,No.YSBR-041(to YW)Joint Funds of the National Natural Science Foundation of China,No.U21A20396(to BH)。
文摘Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a promising treatment for Parkinson’s disease.However,transplanted cells can be injured by mechanical damage during handling and by changes in the transplantation niche.Here,we developed a one-step biomanufacturing platform that uses small-aperture gelatin microcarriers to produce beads carrying midbrain dopaminergic progenitor cells.These beads allow midbrain dopaminergic progenitor cell differentiation and cryopreservation without digestion,effectively maintaining axonal integrity in vitro.Importantly,midbrain dopaminergic progenitor cell bead grafts showed increased survival and only mild immunoreactivity in vivo compared with suspended midbrain dopaminergic progenitor cell grafts.Overall,our findings show that these midbrain dopaminergic progenitor cell beads enhance the effectiveness of neuronal cell transplantation.
基金supported by the National Natural Science Foundation of China (32070534,32370567,82371874,81830032,31872779,82071421,81873736)Key Field Research and Development Program of Guangdong Province (2018B030337001)+3 种基金Guangzhou Key Research Program on Brain Science (202007030008)Department of Science and Technology of Guangdong Province (2021ZT09Y007,2020B121201006)Guangdong Basic and Applied Basic Research Foundation (2023B1515020031,2022A1515012301)Fundamental Research Funds for the Central Universities (Jinan University,21620358)。
文摘PTEN-induced putative kinase 1(PINK1),a mitochondrial kinase that phosphorylates Parkin and other proteins,plays a crucial role in mitophagy and protection against neurodegeneration.Mutations in PINK1 and Parkin can lead to loss of function and early onset Parkinson's disease.However,there is a lack of strong in vivo evidence in rodent models to support the theory that loss of PINK1 affects mitophagy and induces neurodegeneration.Additionally,PINK1 knockout pigs(Sus scrofa)do not appear to exhibit neurodegeneration.In our recent work involving non-human primates,we found that PINK1 is selectively expressed in primate brains,while absent in rodent brains.To extend this to other species,we used multiple antibodies to examine the expression of PINK1 in pig tissues.In contrast to tissues from cynomolgus monkeys(Macaca fascicularis),our data did not convincingly demonstrate detectable PINK1expression in pig tissues.Knockdown of PINK1 in cultured pig cells did not result in altered Parkin and BAD phosphorylation,as observed in cultured monkey cells.A comparison of monkey and pig striatum revealed more PINK1-phosphorylated substrates in the monkey brain.Consistently,PINK1 knockout in pigs did not lead to obvious changes in the phosphorylation of Parkin and BAD.These findings provide new evidence that PINK1expression is specific to primates,underscoring the importance of non-human primates in investigating PINK1function and pathology related to PINK1 deficiency.
基金the National Natural Science Foundation of China[No.81970739,81471071,and 81270948]Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry[SRF for ROCS,SEM][No.2013-693]。
文摘Exosomes,a type of extracellular vesicles(EVs),were first discovered in sheep reticulocytes in 1983[1],and after four years,the name‘exosome’was officially given to them.A variety of cells secrete exosomes under both normal and pathological conditions.Exosomes are mainly products of themultivesicular body formed by intracellular lysosomal invagi nation,and released into the extracellular space by fusion of the outer membrane of the multivesicular body with the cell membrane.
基金Supported by the National Natural Science Foundation of China Grants,No.31600683 and No.U1738103Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA15014000
文摘Platelet transfusion is one of the most reliable strategies to cure patients suffering from thrombocytopenia or platelet dysfunction.With the increasing demand for transfusion,however,there is an undersupply of donors to provide the platelet source.Thus,scientists have sought to design methods for deriving clinical-scale platelets ex vivo.Although there has been considerable success ex vivo in the generation of transformative platelets produced by human stem cells(SCs),the platelet yields achieved using these strategies have not been adequate for clinical application.In this review,we provide an overview of the developmental process of megakaryocytes and the production of platelets in vivo and ex vivo,recapitulate the key advances in the production of SC-derived platelets using several SC sources,and discuss some strategies that apply three-dimensional bioreactor devices and biochemical factors synergistically to improve the generation of large-scale platelets for use in future biomedical and clinical settings.
基金This work was supported by the National Key Research and Development Program of China(2021YFC2700400,2018YFC1004303)the National Natural Science Foundation of China(31988101,82201798,82192874,82071606,82101707)+3 种基金CAMS Innovation Fund for Medical Sciences(2021-I2M-5-001)Shandong Provincial Key Research and Development Program(2020ZLYS02)the Taishan Scholars Program of Shandong Province(ts20190988)the Fundamental Research Funds of Shandong University.
文摘Obesity,which can arise from genetic or environmental factors,has been shown to cause serious damages to the reproductive system.The ovary,as one of the primary regulators of female fertility,is a complex organ comprised of heterogeneous cell types that work together to maintain a normal ovarian microenvironment(OME).Despite its importance,the effect of obesity on the entire ovary remains poorly documented.In this study,we performed ovary single-cell and nanoscale spatial RNA sequencing to investigate how the OME changed under different kinds of obesity,including high-fat diet(HFD)induced obesity and Leptin ablation induced obesity(OB).Our results demonstrate that OB,but not HFD,dramatically altered the proportion of ovarian granulosa cells,theca-interstitial cells,luteal cells,and endothelial cells.Furthermore,based on the spatial dynamics of follicular development,we defined four subpopulations of granulosa cell and found that obesity drastically disrupted the differentiation of mural granulosa cells from small to large antral follicles.Functionally,HFD enhanced follicle-stimulating hormone(FSH)sensitivity and hormone conversion,while OB caused decreased sensitivity,inadequate steroid hormone conversion,and impaired follicular development.These differences can be explained by the differential expression pattern of the transcription factor Foxo1.Overall,our study provides a powerful and high-resolution resource for profiling obesity-induced OME and offers insights into the diverse effects of obesity on female reproductive disorders.
基金supported by grants from National Transgenic Creature Breeding Grand Project(2014ZX08008-005)Chinese Universities Scientific Fund(2014BH032)Natural Science Foundation of China(31501953, 31471352, 31471400 and 31171380)
文摘Background: Mastitis, an infection caused by Gram-positive bacteria, produces udder inflammation and oxidative injury in milk-producing mammals. Toll-like receptor 2(TLR2) is important for host recognition of invading Grampositive microbes. Over-expression of TLR2 in transgenic dairy goats is a useful model for studying various aspects of infection with Gram-positive bacteria, in vivo.Methods: We over-expressed TLR2 in transgenic dairy goats. Pam3CSK4, a component of Gram-positive bacteria,triggered the TLR2 signal pathway by stimulating the monocytes-macrophages from the TLR2-positive transgenic goats, and induced over-expression of activator protein-1(AP-1), phosphatidylinositol 3-kinase(PI3K) and transcription factor nuclear factor kappa B(NF-κB) and inflammation factors downstream of the signal pathway.Results: Compared with wild-type controls, measurements of various oxidative stress-related molecules showed that TLR2, when over-expressed in transgenic goat monocytes-macrophages, resulted in weak lipid damage, high level expression of anti-oxidative stress proteins, and significantly increased m RNA levels of transcription factor NF-E2-related factor-2(Nrf2) and the downstream gene, heme oxygenase-1(HO-1). When Pam3CSK4 was used to stimulate ear tissue in vivo the HO-1 protein of the transgenic goats had a relatively high expression level.Conclusions: The results indicate that the oxidative injury in goats over-expressing TLR2 was reduced following Pam3CSK4 stimulation. The underlying mechanism for this reduction was increased expression of the anti-oxidation gene HO-1 by activation of the Nrf2 signal pathway.
文摘Sertoli cells play essential roles in the process of spermatogenesis such as maintaining the integrity of blood-testis barrier(BTB),engulfing sperm resid ual cytoplasm and secreting critical cytokines.PA1 has been reported to be a unique component of histone lysine methylation modification complex MLL3/4,regulating gene transcription by histone 3 lysine 4 methylation(H3K4me).However,it is unknown whether PA1 is involved in the epigenetic regulation in male reproductive system.
基金supported by the National Key Research-and Development Program of China(2022YFA1103700)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA160000c0)+9 种基金the National Key Research and Development Program of China(2020YFAOB04000,2020YFA0112200,2021YFF1201005,2022YFA1103B00),the STI2030-Major Projects(20212D0202400)the National Natural Science Foundation af China(Grant Nos 81921006,82125011,92149301,9216820191949209,92049304,92049116,32121001,82192863,82122024.82071588,32000500,31900523,82201714,82271600,82201727)CAS Project for Young Scientists in Basic Research(YSBR-076,YSBR-012)the Program of the Beijing Natural Science Foundation(Z190019)China Postdoctoral Science Foundation(2022M712216)кC.Wong Education Foundation(GJTD-2019-06 GTD-2019-08)the lot Proje for Publie Welfare Development and Reform of Beijing-affiliated Medical Restarch Institutes(11000022T000000461062)Young Elte Scientists Sponsorship Progran by CAST YESS20000012,YES520210002)Yout Innovation Promotion Association of CAS(E1CAZWO-401,2022083)the Tencent Foundation(2021-1045)the Plan of Chinese Academy of Sciences(CAS-WX2021SF-0301,CAS-WX2021SF-0101,CAS-WX2022SDC-XK14)Strategic Collaborative Research Program of the Ferring Institute of ReproductiveMedicine,Grant No.FIRMC180305。
文摘The testis is pivotal for male reproduction,and its progressive functional decline in aging is associated with infertility.However,the regulatory mechanism underlying primate testicular aging remains largely elusive.Here,we resolve the aging-related cellular and molecular alterations of primate testicular aging by establishing a single-nucleus transcriptomic atlas.Gene-expression patterns along the spermatogenesis trajectory revealed molecular programs associated with attrition of spermatogonial stem cell reservoir,disturbed meiosis and impaired spermiogenesis along the sequential continuum.Remarkably,Sertoli cell was identified as the cell type most susceptible to aging,given its deeply perturbed age-associated transcriptional profiles.Concomitantly,downregulation of the transcription factor Wilms'Tumor 1(WTi),essential for Sertoli cell homeostasis,was associated with accelerated cellular senescence,disrupted tight junctions,and a compromised cell identity signature,which altogether may help create a hostile microenvironment for spermatogenesis.Collectively,our study depicts in-depth transcriptomic traits of non-human primate(NHP)testicular aging at single-cell resolution,providing potential diagnostic biomarkers and targets for therapeutic interventions against testicular aging and age-related male reproductive diseases.
基金supported by the National Key Research and Development Program of China (2021YFA0805902,2022YFF0710703)National Natural Science Foundation of China (32201257)+1 种基金Science and Technology Innovation Project of Xiongan New Area (2022XAGG0121)Young Elite Scientists Sponsorship Program by the China Association for Science and Technology (2019QNRC001)。
文摘Hereditary hearing loss(HHL),a genetic disorder that impairs auditory function,significantly affects quality of life and incurs substantial economic losses for society.To investigate the underlying causes of HHL and evaluate therapeutic outcomes,appropriate animal models are necessary.Pigs have been extensively used as valuable large animal models in biomedical research.In this review,we highlight the advantages of pig models in terms of ear anatomy,inner ear morphology,and electrophysiological characteristics,as well as recent advancements in the development of distinct genetically modified porcine models of hearing loss.Additionally,we discuss the prospects,challenges,and recommendations regarding the use pig models in HHL research.Overall,this review provides insights and perspectives for future studies on HHL using porcine models.
基金supported by the National Key Research and Development Program of China(2020YFA0804000,2022YFA1103700,2020YFA0112200,2021YFF1201000,the STI2030-Major Projects-2021ZD0202400,2022YFA1103800)the National Natural Science Foundation of China(82201714,81921006,82125011,92149301,92168201,91949209,92049304,92049116,32121001,82192863,82122024,82071588,32000500,82271600,82001477,82201727)+12 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA16000000)CAS Project for Young Scientists in Basic Research(YSBR-076,YSBR-012)the Program of the Beijing Natural Science Foundation(Z190019)the Fellowship of China Postdoctoral Science Foundation(2022M712216)the Project for Technology Development of Beijing-affiliated Medical Research Institutes(11000023T000002036310)the Pilot Project for Public Welfare Development and Reform of Beijing-affiliated Medical Research Institutes(11000022T000000461062)Youth Innovation Promotion Association of CAS(E1CAZW0401,2022083,2023092)Young Elite Scientists Sponsorship Program by CAST(YESS20200012,YESS20210002)the Informatization Plan of Chinese Academy of Sciences(CAS-WX2021SF-0301,CAS-WX2022SDC-XK14,CASWX2021SF-0101)New Cornerstone Science Foundation through the XPLORER PRIZE(2021-1045)Excellent Young Talents Program of Capital Medical University(12300927)Excellent Young Talents Training Program for the Construction of Beijing Municipal University Teacher Team(BPHR202203105)Beijing Hospitals Authority Youth Programme(QML20230806)。
文摘Cullin-RING E3 ubiquitin ligases(CRLs),the largest family of multi-subunit E3 ubiquitin ligases in eukaryotic cells,represent core cellular machinery for executing protein degradation and maintaining proteostasis.Here,we asked what roles Cullin proteins play in human mesenchymal stem cell(hMSC)homeostasis and senescence.To this end,we conducted a comparative aging phenotype analysis by individually knocking down Cullin members in three senescence models:replicative senescent hMSCs,Hutchinson-Gilford Progeria Syndrome hMSCs,and Werner syndrome hMSCs.Among all family members,we found that CUL2 deficiency rendered hMSCs the most susceptible to senescence.To investigate CUL2-specific underlying mechanisms,we then applied CRISPR/Cas9-mediated gene editing technology to generate CUL2-deficient human embryonic stem cells(hESCs).When we differentiated these into h MSCs,we found that CUL2 deletion markedly accelerates hMSC senescence.Importantly,we identified that CUL2 targets and promotes ubiquitin proteasome-mediated degradation of TSPYL2(a known negative regulator of proliferation)through the substrate receptor protein APPBP2,which in turn downregulates one of the canonical aging marker-P21^(waf1/cip1),and thereby delays senescence.Our work provides important insights into how CRL2^(APPBP2)-mediated TSPYL2 degradation counteracts hMSC senescence,providing a molecular basis for directing intervention strategies against aging and aging-related diseases.
基金supported by National Natural Science Foundation of China(T2222029 and U21A20396)Strategic Priority Research Program of Chinese Academy of Sciences(XDA16020802)+1 种基金CAS Project for Young Scientists in Basic Research(YSBR-012)CAS Engineering Laboratory for Intelligent Organ Manufacturing(KFJ-PTXM-039).
文摘Mechanical force is crucial in the whole process of embryonic development.However,the role of trophoblast mechanics during embryo implantation has rarely been studied.In this study,we constructed a model to explore the effect of stiffness changes in mouse trophoblast stem cells(mTSCs)on implantation:microcarrier was prepared by sodium alginate using a droplet microfluidics system,and mTSCs were attached to the microcarrier surface with laminin modifications,called T(micro).Compared with the spheroid,formed by the self-assembly of mTSCs(T(sph)),we could regulate the stiffness of the microcarrier,making the Young’s modulus of mTSCs(367.70±79.81 Pa)similar to that of the blastocyst trophoblast ectoderm(432.49±151.90 Pa).Moreover,T(micro)contributes to improve the adhesion rate,expansion area and invasion depth of mTSCs.Further,T(micro)was highly expressed in tissue migration-related genes due to the activation of the Rho-associated coiled-coil containing protein kinase(ROCK)pathway at relatively similar modulus of trophoblast.Overall,our study explores the embryo implantation process with a new perspective,and provides theoretical support for understanding the effect of mechanics on embryo implantation.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA16030400 to W.L.)the National Key Research and Development Program(2016YFA0100202 and 2017YFA0104401 to T.H.,2018YFA0109701 to R.F.)+1 种基金the National Natural Science Foundation of China(31621004 to Q.Z.and W.L.,31571533 to H.W.,and 31701286 to G.F.)the Key Research Projects of the Frontier Science of the Chinese Academy of Sciences(QYZDY-SSWSMC002 to Q.Z.).
文摘Blastocyst complementation by pluripotent stem cell(PSC)injection is believed to be the most promising method to generate xenogeneic organs.However,ethical issues prevent the study of human chimeras in the late embryonic stage of development.Primate embryonic stem cells(ESCs),which have similar pluripotency to human ESCs,are a good model for studying interspecies chimerism and organ generation.However,whether primate ESCs can be used in xenogenous grafts remains unclear.In this study,we evaluated the chimeric ability of cynomolgus monkey(Macaca fascicularis)ESCs(cmESCs)in pigs,which are excellent hosts because of their many similarities to humans.We report an optimized culture medium that enhanced the anti-apoptotic ability of cmESCs and improved the development of chimeric embryos,in which domesticated cmESCs(D-ESCs)injected into pig blastocysts differentiated into cells of all three germ layers.In addition,we obtained two neonatal interspecies chimeras,in which we observed tissue-specific D-ESC differentiation.Taken together,the results demonstrate the capability of D-ESCs to integrate and differentiate into functional cells in a porcine model,with a chimeric ratio of 0.001-0.0001 in different neonate tissues.We believe this work will facilitate future developments in xenogeneic organogenesis,bringing us one step closer to producing tissue-specific functional cells and organs in a large animal model through interspecies blastocyst complementation.
基金This work was supported by the National Key Research and Development Program of China (2018YFA0107001)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA16010100)+5 种基金the National Key Research and Development Program of China (2018YFC2000100,2018YFA0107203,2017YFA0103304,2017 YFA0102802,2015CB964800,2014CB910503)the National Natural Science Foundation of China (81625009,81330008,91749202, 91749123,31671429,81671377,81771515,31601109,31601158, 81701388,81422017,81601233,81471414,81870228,81822018, 81801399,31801010,81801370 and 81861168034)Program of Beijing Mun icipal Science and Technology Commission (Z151100003915072)Key Research Program of the Chinese Academy of Sciences (KJZDEWTZ-L05)Beijing Municipal Commission of Health and Family Planning (PXM2018_026283_ 000002)Advanced Innovation Center for Human Brain Protection (117212) and the State Key Laboratory of Membrane Biology.
文摘RAP1 is a well-known telomere-binding protein, but its functions in human stem cells have remained unclea匚 Here we generated RAP1 -deficient human embryonic stem cells (hESCs) by using CRISPR/Cas9 technique and obtained RAP1-deficient human mesenchymal stem cells (hMSCs) and neural stem cells (hNSCs) via directed differentiation. In both hMSCs and hNSCs, RAP1 not only negatively regulated telomere length but also acted as a transcriptional regulator of RELN by tuning the methylation status of its gene promoter. RAP1 deficiency enhanced self-renewal and delayed senescence in hMSCs, but not in hNSCs, suggesting complicated lineage-specific effects of RAP1 in adult stem cells.Altogether, these results demonstrate for the first time that RAP1 plays both telomeric and nontelomeric roles in regulating human stem cell homeostasis.
基金supported by the National Natural Science Foundation of China (31471395)
文摘Pluripotent stem cells(PSCs) are cells that can differentiate into any type of cells in the body, therefore have valuable promise in regenerative medicine of cell replacement therapies and tissue/organ engineering. PSCs can be derived either from early embryos or directly from somatic cells by epigenetic reprogramming that result in customized cells from patients. Here we summarize the methods of deriving PSCs, the various types of PSCs generated with different status, and their versatile applications in both clinical and embryonic development studies. We also discuss an intriguing potential application of PSCs in constructing tissues/organs in large animals by interspecies chimerism. All these emerging findings are likely to contribute to the breakthroughs in biological research and the prosperous prospects of regenerative medicine.
基金supported by the National Natural Science Foundation of China(32030013,31821001)。
文摘The molecular mechanisms underpinning temperature-dependent sex determination(TSD)in reptiles have attracted great biological interest for many years.However,which genetic factors are essential for TSD remain elusive,especially regarding female sex determination.Cytochrome P450 family 19 subfamily A member 1(Cyp19a1)encodes the endoplasmic reticulum enzyme aromatase,which participates in the catalytic conversion of androgens to estrogens,and is implicated in sexual differentiation in many species.However,whether Cyp19a1 plays a critical role in determining gonadal sexual fate in TSD species remains to be elucidated.In the current study,Cyp19a1 exhibited a temperature-dependent and sexually dimorphic expression pattern,preceding gonadal sex differentiation in a TSD turtle species(Mauremys reevesii).Sexual phenotype of the turtles was successfully reversed by aromatase inhibitor treatment at the female-producing temperature(FPT).Furthermore,exogenous estradiol(E2)treatment led to complete male-to-female sex reversal at the male-producing temperature(MPT),accompanied by rapid up-regulation of Cyp19a1.Thus,Cyp19a1 appears to be essential for female sex determination in M.reevesii,suggesting a vital role in the female TSD pathway.
文摘Dear Editor,Genome-scale screening is a powerful method used to explore phenotypes that are of interest,and numerous screening systems have been built for functional sites identification.Classical genetic screening in eukaryotes has been performed using chemical mutagens(Chen et al.,2000),transposon mediated gene trapping(Dupuy et al.,2005),and CRISPR-Cas9 system(Wang et al.,2014).
基金the National Key Research and Development Program of China(2018YFA0107203)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA16010000)+10 种基金the National Key Research and Development Program of China(2020YFA0804000,2018YFC2000100,2020YFA0112201,2017YFA0103304,2017YFA0102802,2020YFA0113400,2019YFA0110100)the National Natural Science Foundation of China(Grant Nos.81901433,81921006,81625009,91749202,81861168034,91949209,92049304,81822018,92049116,82071588,32000500,81922027,81870228,82125011,82122024,32100937,92149301,92168201)the Key Research Program of the Chinese Academy of Sciences(KFZD-SW-221)the Program of Beijing Municipal Science and Technology Commission(Z191100001519005)the Program of the Beijing Natural Science Foundation(Z190019,JQ20031)K.C.Wong Education Foundation(GJTD-2019-06,GJTD-2019-08)Beijing Hospitals Authority Youth Programme(QML20200802)Youth Innovation Promotion Association of CAS(2021078,E1CAZW0401)the 14th Five-year Network Security and Informatization Plan of Chinese Academy of Sciences(WX145XQ07-18)the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences(2020-JKCS-011)the State Key Laboratory of Stem Cell and Reproductive Biology,the State Key Laboratory of Membrane Biology,and the Milky Way Research Foundation(MWRF).
文摘Dear Editor,Stem cells,including pluripotent stem cells and adult stem cells,possess the remarkable capability of being able to selfrenew while at the same time having potential to differentiate into different cell lineages and functionally distinct cell types.Human embryonic stem cells(hESCs)can differentiate into all adult stem cell types,including human mesenchymal stem cells(hMSCs)and human neural stem cells(hNSCs),but can also give rise to all terminally differentiated cell types(Wang et al.,2021a).Through the continuous replenishment of differentiated cells,stem cells support tissue homeostasis and respond to tissue injuries.Given the promising applications of stem cells in cell therapy and regenerative medicine,insights into molecular events underlying stem cell maintenance,self-renewal ability and pluripotency,continue to garner strong interest(Shan et al.,2021).Although metabolic pathways have been implicated in the reciprocal regulations of stem cell self-renewal and differentiation as well as organ homeostatic maintenance(Garcia-Prat et al.,2017),central aspects of how metabolic requirements differ and are regulated across the various types of human stem cells in our body remain enigmatic.
基金supported by the National Key Research and Development Program of China(2018YFC2000100)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA16000000)+9 种基金the National Natural Science Foundation of China(8190143281921006,82125011,92149301,92168201,91949209,92049304,92049116,32121001,82192863,82122024,82071588,81861168034,81922027,81870228,32100937,31900524,82201727)the National Key Research and Development Program of China(2020YFA0804000,2020YFA0113400,2020YFA0112200,2018YFA0107203,the STI2030-Major Projects-2021ZD0202400,2021YFF1201005,2022YFA1103700,2022YFA1103800)CAS Project for Young Scientists in Basic Research(YSBR-076,YSBR-012)the Program of the Beijing Natural Science Foundation(Z190019,JQ20031)K.C.Wong Education Foundation(GJTD-2019-06,GJTD-2019-08)Young Elite Scientists Sponsorship Program by CAST(YESS20200012)Youth Innovation Promotion Association of CAS(EiCAZW0401)the Pilot Project for Public Welfare Development and Reform of Beijing-affliated Medical Research Institutes(11000022T000000461062)the Informatization Plan of Chinese Academy of Sciences(CAS-WX2021SF-0301,CASWX2022SDC-XK14)CAS Special Research Assistant(SRA)Program,and the Tencent Foundation(2021-1045).
文摘Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders,the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown.Here,we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem celis(hMSCs).Genetic inactivation of 4E-BP1 in hMSCs compromises mitochondrial respiration,increases mitochondrial reactive oxygen species(Ros)production,and accelerates cellular senescence.Mechanistically,the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes,especially several key subunits of complex III including UQCRC2.Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs.These findings together demonstrate that 4E-BP1 functions as a geroprotector to mitigate human stem cell senescence and maintain mitochondrial homeostasis,particularly for the mitochondrial respiration complex Il,thus providing a new potential target to counteract human stem cell senescence.
基金supported by the China National Basic Research Program(2013CB966901,2012CBA01303)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA01040108)+1 种基金National Thousand Young Talents Program to Tongbiao Zhaothe National Natural Science Foundation of China Program((31271592,31570995)to Tongbiao Zhao,(31400831)to Jiani Cao)
文摘Multiple sclerosis(MS) is an autoimmune disease of the central nervous system(CNS), with focal T lymphocytic infiltration and damage of myelin and axons. The underlying mechanism of pathogenesis remains unclear and there are currently no effective treatments. The development of neural stem cell(NSC) transplantation provides a promising strategy to treat neurodegenerative disease. However, the limited availability of NSCs prevents their application in neural disease therapy. In this study, we generated NSCs from induced pluripotent stem cells(iPSCs) and transplanted these cells into mice with experimental autoimmune encephalomyelitis(EAE), a model of MS. The results showed that transplantation of iPSC-derived NSCs dramatically reduced T cell infiltration and ameliorated white matter damage in the treated EAE mice. Correspondingly, the disease symptom score was greatly decreased, and motor ability was dramatically rescued in the iPSC-NSC-treated EAE mice, indicating the effectiveness of using iPSC-NSCs to treat MS. Our study provides pre-clinical evidence to support the feasibility of treating MS by transplantation of iPSC-derived NSCs.
