Integrative omics analysis elucidates the genetic basis underlying seed weight and oil content in soybean.

Synergistic optimization of key agronomic traits by traditional breeding has dramatically enhanced crop productivity in the past decades. However, the genetic basis underlying coordinated regulation of yield- and quality-related traits remains poorly understood. Here, we dissected the genetic architectures of seed weight and oil content by combining genome-wide association studies (GWAS) and transcriptome-wide association studies (TWAS) using 421 soybean (Glycine max) accessions. We identified 26 and 33 genetic loci significantly associated with seed weight and oil content by GWAS, respectively, and detected 5,276 expression quantitative trait loci (eQTLs) regulating expression of 3,347 genes based on population transcriptomes. Interestingly, a gene module (IC79), regulated by two eQTL hotspots, exhibited significant correlation with both seed weigh and oil content. Twenty-two candidate causal genes for seed traits were further prioritized by TWAS, including Regulator of Weight and Oil of Seed 1 (GmRWOS1), which encodes a sodium pump protein. GmRWOS1 was verified to pleiotropically regulate seed weight and oil content by gene knockout and overexpression. Notably, allelic variations of GmRWOS1 were strongly selected during domestication of soybean. This study uncovers the genetic basis and network underlying regulation of seed weight and oil content in soybean and provides a valuable resource for improving soybean yield and quality by molecular breeding.

Landscape of molecular crosstalk between SARS-CoV-2 infection and cardiovascular diseases: emphasis on mitochondrial dysfunction and immune-inflammation.

BACKGROUND: SARS-CoV-2, the pathogen of COVID-19, is a worldwide threat to human health and causes a long-term burden on the cardiovascular system. Individuals with pre-existing cardiovascular diseases are at higher risk for SARS-CoV-2 infection and tend to have a worse prognosis. However, the relevance and pathogenic mechanisms between COVID-19 and cardiovascular diseases are not yet completely comprehended. METHODS: Common differentially expressed genes (DEGs) were obtained in datasets of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) infected with SARS-CoV-2 and myocardial tissues from heart failure patients. Further GO and KEGG pathway analysis, protein-protein interaction (PPI) network construction, hub genes identification, immune microenvironment analysis, and drug candidate predication were performed. Then, an isoproterenol-stimulated myocardial hypertrophy cell model and a transverse aortic constriction-induced mouse heart failure model were employed to validate the expression of hub genes. RESULTS: A total of 315 up-regulated and 78 down-regulated common DEGs were identified. Functional enrichment analysis revealed mitochondrial metabolic disorders and extensive immune inflammation as the most prominent shared features of COVID-19 and cardiovascular diseases. Then, hub DEGs, as well as hub immune-related and mitochondria-related DEGs, were screened. Additionally, nine potential therapeutic agents for COVID-19-related cardiovascular diseases were proposed. Furthermore, the expression patterns of most of the hub genes related to cardiovascular diseases in the validation dataset along with cellular and mouse myocardial damage models, were consistent with the findings of bioinformatics analysis. CONCLUSIONS: The study unveiled the molecular networks and signaling pathways connecting COVID-19 and cardiovascular diseases, which may provide novel targets for intervention of COVID-19-related cardiovascular diseases.

The Rice Circadian Clock Regulates Tiller Growth and Panicle Development Through Strigolactone Signaling and Sugar Sensing.

Circadian clocks regulate growth and development in plants and animals, but the role of circadian regulation in crop production is poorly understood. Rice (Oryza sativa) grain yield is largely determined by tillering, which is mediated by physiological and genetic factors. Here we report a regulatory loop that involves the circadian clock, sugar, and strigolactone (SL) pathway to regulate rice tiller-bud and panicle development. Rice CIRCADIAN CLOCK ASSOCIATED1 (OsCCA1) positively regulates expression of TEOSINTE BRANCHED1 (OsTB1, also known as FC1), DWARF14 (D14), and IDEAL PLANT ARCHITECTURE1 (IPA1, also known as OsSPL14) to repress tiller-bud outgrowth. Downregulating and overexpressing OsCCA1 increases and reduces tiller numbers, respectively, whereas manipulating PSEUDORESPONSE REGULATOR1 (OsPPR1) expression results in the opposite effects. OsCCA1 also regulates IPA1 expression to mediate panicle and grain development. Genetic analyses using double mutants and overexpression in the mutants show that OsTB1, D14, and IPA1 act downstream of OsCCA1 Sugars repress OsCCA1 expression in roots and tiller buds to promote tiller-bud outgrowth. The circadian clock integrates sugar responses and the SL pathway to regulate tiller and panicle development, providing insights into improving plant architecture and yield in rice and other cereal crops.

Histone H3K27 dimethylation landscapes contribute to genome stability and genetic recombination during wheat polyploidization.

Bread wheat (Triticum aestivum) is an allohexaploid that was formed via two allopolyploidization events. Growing evidence suggests histone modifications are involved in the response to 'genomic shock' and environmental adaptation during polyploid formation and evolution. However, the role of histone modifications, especially histone H3 lysine-27 dimethylation (H3K27me2), in genome evolution remains elusive. Here we analyzed H3K27me2 and H3K27me3 profiles in hexaploid wheat and its tetraploid and diploid relatives. Although H3K27me3 levels were relatively stable among wheat species with different ploidy levels, H3K27me2 intensities increased concurrent with increased ploidy levels, and H3K27me2 peaks were colocalized with massively amplified DTC transposons (CACTA family) in euchromatin, which may silence euchromatic transposons to maintain genome stability during polyploid wheat evolution. Consistently, the distribution of H3K27me2 is mutually exclusive with another repressive histone mark, H3K9me2, that mainly silences transposons in heterochromatic regions. Remarkably, the regions with low H3K27me2 levels (named H3K27me2 valleys) were associated with the formation of DNA double-strand breaks in genomes of wheat, maize (Zea mays) and Arabidopsis. Our results provide a comprehensive view of H3K27me2 and H3K27me3 distributions during wheat evolution, which support roles for H3K27me2 in silencing euchromatic transposons to maintain genome stability and in modifying genetic recombination landscapes. These genomic insights may empower breeding improvement of crops.

Dynamic and reversible DNA methylation changes induced by genome separation and merger of polyploid wheat.

BACKGROUND: Wheat is a powerful genetic model for studying polyploid evolution and crop domestication. Hexaploid bread wheat was formed by two rounds of interspecific hybridization and polyploidization, processes which are often accompanied by genetic and epigenetic changes, including DNA methylation. However, the extent and effect of such changes during wheat evolution, particularly from tetraploid-to-hexaploid wheat, are currently elusive. RESULTS: Here we report genome-wide DNA methylation landscapes in extracted tetraploid wheat (ETW, AABB), natural hexaploid wheat (NHW, AABBDD), resynthesized hexaploid wheat (RHW, AABBDD), natural tetraploid wheat (NTW, AABB), and diploid (DD). In the endosperm, levels of DNA methylation, especially in CHG (H=A, T, or C) context, were dramatically decreased in the ETW relative to natural hexaploid wheat; hypo-differentially methylated regions (DMRs) (850,832) were 24-fold more than hyper-DMRs (35,111). Interestingly, those demethylated regions in ETW were remethylated in the resynthesized hexaploid wheat after the addition of the D genome. In ETW, hypo-DMRs correlated with gene expression, and TEs were demethylated and activated, which could be silenced in the hexaploid wheat. In NHW, groups of TEs were dispersed in genic regions of three subgenomes, which may regulate the expression of TE-associated genes. Further, hypo-DMRs in ETW were associated with reduced H3K9me2 levels and increased expression of histone variant genes, suggesting concerted epigenetic changes after separation from the hexaploid. CONCLUSION: Genome merger and separation provoke dynamic and reversible changes in chromatin and DNA methylation. These changes correlate with altered gene expression and TE activity, which may provide insights into polyploid genome and wheat evolution.

Light induces gene expression to enhance the synthesis of storage reserves in Brassica napus L. embryos.

KEY MESSAGE: In this manuscript, we disclosed the influence of light on the accumulation of storage reserves in B. napus embryos.1.Light induced the gene expression in the developing embryos of B. napus.2.Light promoted the starch synthesis in chloroplasts of B. napus embryos.3.Light enhanced the metabolic activity of storage reserve synthesis in B. napus embryos. Light influences the accumulation of storage reserves in embryos, but the molecular mechanism was not fully understood. Here, we monitored the effects of light on reserve biosynthesis in Brassica napus by comparing embryos from siliques grown in normal light conditions to those that were shaded or masked (i.e., darkened completely). Masked embryos developed more slowly, weighed less, and contained fewer proteins and lipids than control embryos. They also had fewer and smaller oil bodies than control embryos and lacked chloroplasts, where starch grains are usually synthesized. The levels of most amino acids, carbohydrates, and fatty acids were higher in masked embryos than in control or shaded embryos, whereas the levels of these metabolites in the masked endosperms were lower than those in control and shaded endosperm. Transcriptome analysis indicated that genes involved in photosynthesis (42 genes), amino acid biosynthesis (51 genes), lipid metabolism (61 genes), and sugar transport (13 genes) were significantly repressed in masked embryos. Our results suggest that light contributes to reserve accumulation in embryos by inducing the expression of metabolic genes, thereby enhancing the biosynthesis of storage reserves.

Asymmetrical changes of gene expression, small RNAs and chromatin in two resynthesized wheat allotetraploids.

Polyploidy occurs in some animals and all flowering plants, including important crops such as wheat. The consequences of polyploidy in crops remain elusive, partly because their progenitors are unknown. Using two resynthesized wheat allotetraploids Sl Sl AA and AADD with known diploid progenitors, we analyzed mRNA and small RNA transcriptomes in the endosperm, compared transcriptomes between endosperm and root in AADD, and examined chromatin changes in the allotetraploids. In the endosperm, there were more non-additively expressed genes in Sl Sl AA than in AADD. In AADD, non-additively expressed genes were developmentally regulated, and the majority (62-70%) were repressed. The repressed genes in AADD included a group of histone methyltransferase gene homologs, which correlated with reduced histone H3K9me2 levels and activation of various transposable elements in AADD. In Sl Sl AA, there was a tendency for expression dominance of Sl over A homoeologs, but the histone methyltransferase gene homologs were additively expressed, correlating with insignificant changes in histone H3K9me2 levels. Moreover, more 24-nucleotide small inferring RNAs (siRNAs) in the A subgenome were disrupted in AADD than in Sl Sl AA, which were associated with expression changes of siRNA-associated genes. Our results indicate that asymmetrical changes in siRNAs, chromatin modifications, transposons and gene expression coincide with unstable AADD genomes and stable Sl Sl AA genomes, which could help explain the evolutionary trajectories of wheat allotetraploids formed by different progenitors.

Integrated metabolite profiling and transcriptome analysis reveals a dynamic metabolic exchange between pollen tubes and the style during fertilization of Brassica napus.

KEY MESSAGE: In this study, we analyzed the transcriptome and metabolite profile of the style to explore the essential metabolites and specific genes for pollen tube growth of B. napus in vivo. For sexual reproduction of flowering plants, pollen must germinate on the stigma and the pollen tube must grow through the style to deliver the sperm nuclei to the female gametophyte cells. During this process, the rapidly growing pollen tube can cover substantial distances. Despite the clear requirements for energy and cellular building blocks in this process, few studies have examined the role of metabolism in the style for pollen tube elongation. In this study, we comprehensively analyzed the transcriptome and metabolite profiles during pollen germination and pollen tube growth in the style in Brassica napus. We profiled the transcripts and metabolites stored in pollen and identified many transcripts related to metabolic pathways. Mature pollen contained low levels of nutrients, whereas the styles contained high levels of diverse nutrients. The levels of most nutrients in the style, especially metabolites for cell wall synthesis and energy metabolism, rapidly decreased at 2 h after pollination, along with pollen germination and pollen tube elongation through the style. A subset of genes involved in cell wall synthesis and nutrient transport were expressed specifically in styles at 1 h after pollination. These results demonstrated that successful fertilization involves the transcripts and nutrients stored in mature pollen, and specific gene expression and stored nutrients in the style. Therefore, these findings enhance our understanding of fertilization in B. napus.

Genetics and evolution of MIXTA genes regulating cotton lint fiber development.

Cotton, with cellulose-enriched mature fibers, is the largest source of natural textiles. Through a map-based cloning strategy, we isolated an industrially important lint fiber development gene (Li3 ) that encodes an MYB-MIXTA-like transcription factor (MML) on chromosome D12 (GhMML4_D12). Virus-induced gene silencing or decreasing the expression of the GhMML4_D12 gene in n2 NSM plants resulted in a significant reduction in epidermal cell prominence and lint fiber production. GhMML4_D12 is arranged in tandem with GhMML3, another MIXTA gene responsible for fuzz fiber development. These two very closely related MIXTA genes direct fiber initiation production in two specialized cell forms: lint and fuzz fibers. They may control the same metabolic pathways in different cell types. The MIXTAs expanded in Malvaceae during their evolution and produced a Malvaceae-specific family that regulates epidermal cell differentiation, different from the gene family that regulates leaf hair trichome development. Cotton has developed a unique transcriptional regulatory network for fiber development. Characterization of target genes regulating fiber production has provided insights into the molecular mechanisms underlying cotton fiber development and has allowed the use of genetic engineering to increase lint yield by inducing more epidermal cells to develop into lint rather than fuzz fibers.

Both maternally and paternally imprinted genes regulate seed development in rice.

Genetic imprinting refers to the unequal expression of paternal and maternal alleles of a gene in sexually reproducing organisms, including mammals and flowering plants. Although many imprinted genes have been identified in plants, the functions of these imprinted genes have remained largely uninvestigated. We report genome-wide analysis of gene expression, DNA methylation and small RNAs in the rice endosperm and functional tests of five imprinted genes during seed development using Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated gene9 (CRISPR/Cas9) gene editing technology. In the rice endosperm, we identified 162 maternally expressed genes (MEGs) and 95 paternally expressed genes (PEGs), which were associated with miniature inverted-repeat transposable elements, imprinted differentially methylated loci and some 21-22 small interfering RNAs (siRNAs) and long noncoding RNAs (lncRNAs). Remarkably, one-third of MEGs and nearly one-half of PEGs were associated with grain yield quantitative trait loci. Most MEGs and some PEGs were expressed specifically in the endosperm. Disruption of two MEGs increased the amount of small starch granules and reduced grain and embryo size, whereas mutation of three PEGs reduced starch content and seed fertility. Our data indicate that both MEGs and PEGs in rice regulate nutrient metabolism and endosperm development, which optimize seed development and offspring fitness to facilitate parental-offspring coadaptation. These imprinted genes and mechanisms could be used to improve the grain yield of rice and other cereal crops.

Histone Modifications Define Expression Bias of Homoeologous Genomes in Allotetraploid Cotton.

Histone modifications regulate gene expression in eukaryotes, but their roles in gene expression changes in interspecific hybrids or allotetraploids are poorly understood. Histone modifications can be mapped by immunostaining of metaphase chromosomes at the single cell level and/or by chromatin immunoprecipitation-sequencing (ChIP-seq) for analyzing individual genes. Here, we comparatively analyzed immunostained metaphase chromosomes and ChIP-seq of individual genes, which revealed a chromatin basis for biased homoeologous gene expression in polyploids. We examined H3K4me3 density and transcriptome maps in root-tip cells of allotetraploid cotton (Gossypium hirsutum). The overall H3K4me3 levels were relatively equal between A and D chromosomes, which were consistent with equal numbers of expressed genes between the two subgenomes. However, intensities per chromosomal area were nearly twice as high in the D homeologs as in the A homeologs. Consistent with the cytological observation, ChIP-seq analysis showed that more D homeologs with biased H3K4me3 levels than A homeologs with biased modifications correlated with the greater number of the genes with D-biased expression than that with A-biased expression in most homeologous chromosome pairs. Two chromosomes displayed different expression levels compared with other chromosomes, which correlate with known translocations and may affect the local chromatin structure and expression levels for the genes involved. This example of genome-wide histone modifications that determine expression bias of homeologous genes in allopolyploids provides a molecular basis for the evolution and domestication of polyploid species, including many important crops.

Aortic Valve Myxoma in a Young Man: A Case Report and Review of Literature.

Myxoma is the most commonly found cardiac primary tumor. The left atrium is the most common localization of myxoma, followed by the right atrium. However, it is rare in the left and right ventricles. Myxoma originating from cardiac valves is extremely rare. This article presents a case of a 17-year-old male who was admitted due to heart murmur for one year. Transthoracic echocardiography indicated a 1.9 cm round solid mass in the left ventricular outflow tract. Excision surgery and aortic valve replacement were performed in this patient. Histopathology revealed the mass as a myxoma. The aortic valve remains a very rare myxoma localization position. Echocardiography can provide a precise method for myxoma diagnosis. Early excision associated with valve replacement can provide good curative effects.

Small interfering RNAs from bidirectional transcripts of GhMML3_A12 regulate cotton fiber development.

Natural antisense transcripts (NATs) are commonly observed in eukaryotic genomes, but only a limited number of such genes have been identified as being involved in gene regulation in plants. In this research, we investigated the function of small RNA derived from a NAT in fiber cell development. Using a map-based cloning strategy for the first time in tetraploid cotton, we cloned a naked seed mutant gene (N1 ) encoding a MYBMIXTA-like transcription factor 3 (MML3)/GhMYB25-like in chromosome A12, GhMML3_A12, that is associated with fuzz fiber development. The extremely low expression of GhMML3_A12 in N1 is associated with NAT production, driven by its 3' antisense promoter, as indicated by the promoter-driven histochemical staining assay. In addition, small RNA deep sequencing analysis suggested that the bidirectional transcriptions of GhMML3_A12 form double-stranded RNAs and generate 21-22 nt small RNAs. Therefore, in a fiber-specific manner, small RNA derived from the GhMML3_A12 locus can mediate GhMML3_A12 mRNA self-cleavage and result in the production of naked seeds followed by lint fiber inhibition in N1 plants. The present research reports the first observation of gene-mediated NATs and siRNA directly controlling fiber development in cotton.

Preoperative ejection fraction determines early recovery of left ventricular end-diastolic dimension after aortic valve replacement for chronic severe aortic regurgitation.

BACKGROUND: In patients with chronic severe aortic regurgitation (AR), aortic valve replacement (AVR) has been proved to promote left ventricular (LV) remodeling, especially LV end-diastolic dimension (LVEDD) reduction. However, there is little research whether postoperative LVEDD could return to normal parameter after AVR. The objective of this study was to determine predictors for the recovery of dilated LVEDD early after AVR. METHODS: The echocardiographic data of 105 patients, who underwent AVR for chronic pure AR between January 2005 and December 2011, were analyzed at the preoperative (3-7 d), early (6-8 mo), and late (2-y) postoperative stages, retrospectively. According to the baseline level, LVEDD >70 mm or LV end-systolic dimension (LVESD) >50 mm or LVESD index >25 mm/m(2) were defined as severe LV dilation. Patients were then categorized into two groups (group 1: severe LV dilation; group 2: nonsevere LV dilation). RESULTS: In all patients, four-fifth of the reduction in LV dimension occurred at early (6-8 mo) postoperative stage. The patients in both groups had significant decreases in the LVEDD and LVESD early after AVR, with an additional but insignificant reduction at late postoperative stage. The ejection fraction (EF) in both groups significantly increased at either early or late stage. However, the LVEDD and LVESD in group 1 were larger than those in group 2, and the EF in group 1 was lower than that in group 2 at early postoperative stage. By multivariate analysis, we found that the preoperative EF was a good predictor for the recovery of dilated LVEDD early after AVR (P = 0.009). Receiver-operating characteristics analysis showed that EF >52% was the best cut-off value for the recovery of LVEDD. CONCLUSIONS: In patients with chronic pure AR, preoperative EF may be a good predictor for successful recovery of dilated LVEDD early after AVR.

Injection of Sca-1+/CD45+/CD31+ mouse bone mesenchymal stromal-like cells improves cardiac function in a mouse myocardial infarct model.

The objective of this study was to screen mouse bone marrow mesenchymal stromal cells (BMSCs) according to expression of cardiac stem cell (CSC) surface antigens and to assess the effects of resulting BMSC-like subsets on cardiac function after injection in a mouse myocardial infarct model. BMSCs were sorted by magnetic beads according to the expression of differentiation antigens on the surface of mouse CSCs, and four subsets were identified on the basis of CD45 and CD31 expression: stem cell antigen-1+ (Sca-1+)/CD45-/CD31-, Sca-1+/CD45-/CD31+, Sca-1+/CD45+/CD31-, and Sca-1+/CD45+/CD31+. When co-cultured with myocardial stem cells and 5-aza-2'-deoxycytidine for 14 days, each subset showed expression of cardiac markers α-actin, connexin 43, desmin, and cardiac troponin I; however, expression was greatest in Sca-1+/CD45+/CD31+ cells. To assess the ability of these cells to improve cardiac function, each subset was injected separately into mice with myocardial infarct induced by ligation of the left anterior descending coronary artery, and in vivo cardiac dual inversion recovery (DIR) imaging and Doppler echocardiography were performed 48 h, 96 h, and 7 days after injection. Results indicated that Sca-1+/CD45+/CD31+ cells were superior in improving cardiac function compared with the other subsets and with unsorted BMSCs. These results suggest that mouse BMSC cells are polyclonal and that the BMSC-like Sca-1+/CD45+/CD31+ subset was effective in directing cardiac differentiation and improving cardiac function in mice with myocardial infarcts.

Association analysis of fiber quality traits and exploration of elite alleles in Upland cotton cultivars/accessions (Gossypium hirsutum L.).

Exploring the elite alleles and germplasm accessions related to fiber quality traits will accelerate the breeding of cotton for fiber quality improvement. In this study, 99 Gossypium hirsutum L. accessions with diverse origins were used to perform association analysis of fiber quality traits using 97 polymorphic microsatellite marker primer pairs. A total of 107 significant marker-trait associations were detected for three fiber quality traits under three different environments, with 70 detected in two or three environments and 37 detected in only one environment. Among the 70 significant marker-trait associations, 52.86% were reported previously, implying that these are stable loci for target traits. Furthermore, we detected a large number of elite alleles associated simultaneously with two or three traits. These elite alleles were mainly from accessions collected in China, introduced to China from the United States, or rare alleles with a frequency of less than 5%. No one cultivar contained more than half of the elite alleles, but 10 accessions were collected from China and the two introduced from the United States did contain more than half of these alleles. Therefore, there is great potential for mining elite alleles from germplasm accessions for use in fiber quality improvement in modern cotton breeding.

Suppression of NF-kappaB p65 expression attenuates delayed xenograft rejection.

BACKGROUND: Delayed xenograft rejection (DXR) involves type II vascular endothelial cell (VEC) activation including upregulation of pro-inflammatory genes, which contributes to infiltration into the graft and a complex process of cytokine production. Approaches to prevent DXR have shown limited success. In this study, we modified heart donors using siRNA in an attempt to attenuate DXR and to improve xenograft survival in the mouse-to-rat heterotopic heart transplant model. METHODS: siRNA technology was used to inhibit NF-kappaB p65 gene expression in vivo in mice. After the donor was transfected with siRNA, the effects of NF-kappaB siRNA on DXR and expression of NF-kappaB and pro-inflammatory genes were evaluated in a concordant mouse-to-rat cardiac xenograft model. RESULTS: Treatment of NF-kappaB siRNA prolonged median heart graft survival time in the recipient rats from 1.7 days in a PBS control group to 5.4 days in the NF-kappaB siRNA-treated group (P < 0.05). Compared with normal mouse hearts, the NF-kappaB p65 mRNA relative levels following siRNA injection in the donors decreased significantly (approximately 70% reduction) in grafts harvested 12 h after transplantation. The mRNA levels of VCAM-1, ICAM-1, and interleukin-1 displayed a similar reduction. Histological evaluation using light and electron microscopy showed that damage of endothelial cells after NF-kappaB siRNA treament occured at a later time. CONCLUSION: Transfection of NF-kappaB p65 siRNA in donor animals can delay the emergence of DXR. This treatment may be used as part of strategies to minimize the complex and multi-faceted rejection responses in vascularized xenografts.

Combined intrathymic and intravenous injection of mesenchymal stem cells can prolong the survival of rat cardiac allograft associated with decrease in miR-155 expression.

BACKGROUND: Mesenchymal stem cells (MSCs) have the potential to improve graft outcomes and promote allograft tolerance. In this study, we examined the effects and mechanism of combined intrathymic (i.t.) and intravenous (i.v.) injection of MSCs on the survival of transplanted hearts in a rat allograft model. METHODS: Recipient Sprague-Dawley rats were transplanted with hearts from Wistar rats. Wistar rat MSCs were infused via i.t. or i.v. or combined i.t. and i.v. (i.t./i.v.) injection at designated intervals. In vitro mixed lymphocyte reaction assays were performed to assess the immunosuppressive capacity of MSCs. Mesenchymal stem cell surface markers and CD4+, CD25+, and Foxp3+ T-cells in the peripheral blood were detected using flow cytometry analysis. The expression of microRNAs and cytokines in graft infiltrating lymphocytes was analyzed by real-time polymerase chain reaction. RESULTS: The MSCs cultured in vitro had multipotential differentiation capacity. Mixed lymphocyte reaction assays showed that donor-derived MSCs could not stimulate a proliferative response of recipient lymphocytes and could markedly suppress T-cell responses. Survival of the allografts was significantly prolonged by administration of i.t./i.v. injection of MSCs compared with controls, with a mean survival of 32.2 versus 6.5 d, respectively. Compared with the syngeneic groups posttransplant, miR-155 expression was significantly increased in the allogeneic group, and could be restored by injection of MSCs, especially i.t./i.v. injection of MSCs. Moreover, i.t./i.v. injection of MSCs decreased the level of interleukin (IL)-2 and interferon-gamma, but increased the levels of IL-4 and IL-10 in the allogeneic group. More important, i.t./i.v. injection of MSCs was the best way to increase the percentage of CD4+, CD25+, and Foxp3+ T-cell peripheral blood. CONCLUSIONS: Our results indicated that i.t./i.v. injection of MSCs can prolong the survival of rat cardiac allograft, which may be associated with down-regulating miR-155 expression, a shift in the Th1/Th2 balance, and up-regulation of Treg cells expression.

[Efficacy of subgroup mouse bone mesenchymal stem cells on mobilizing autologous cardiac stem cells and repairing ischemic myocardial tissue].

OBJECTIVE: To search for the bone mesenchymal stem cell (MSC) subgroup which might be more effective on repairing myocardial damage. METHODS: In this experiment, four MSC subgroups were defined based on the surface differentiation antigen detection of mouse bone mesenchymal stem cells (mBMSCs): SCA-1(+)/CD45(+)/CD31(+), SCA-1(+)/CD45(+)/CD31(-), SCA-1(+)/CD45(-)/CD31(-) and SCA-1(+)/CD45(-)/CD31(+). These subgroup cells and unselected mBMSCs were injected into infarcted mouse via tail vein. Echocardiographic heart function measurement and in vivo DiR-labeled stem cells imaging were performed at 48 h after injection. In situ C-kit (a flag antigen of cardiac stem cells) and cardiac-specific differentiation antigen immunohistochemistry detection was made in the infarcted myocardium. RESULTS: The capacity of the SCA-1(+)/CD45(+)/CD31(+) cells on improving heart function was significantly higher than other cell groups (all P < 0.05). In vivo imaging showed that the mean fluorescence intensity of the SCA-1(+)/CD45(+)/CD31(+) cells was also higher than other cell groups (all P < 0.05). Number of cardiac stem cells in the infracted myocardium was significantly increased after the injection of all subgroup cells and unsorted mBMSCs cells for 48 h compared untreated infracted myocardium. The capacity of mobilizing cardiac stem cells is as follows: SCA-1(+)/CD45(+)/CD31(+) >SCA-1(+)/CD45(-)/CD31(+) >SCA-1(+)/CD45(-)/CD31(-) >SCA-1(+)/CD45(+)/CD31(-). CONCLUSION: The SCA-1(+)/CD45(+)/CD31(+) subgroups of mBMSCs exhibites the highest capacity to improve cardiac function after myocardial infarction and to mobilize autologous cardiac stem cells compared with other mBMSCs subgroups and unsorted mBMSCs cells.