Papers by Erin Lambers
Heart disease is the number one cause of morbidity and mortality in the world and is a major heal... more Heart disease is the number one cause of morbidity and mortality in the world and is a major health and economic burden costing the United States Health Care System more than $200 billion annually. A major cause of heart disease is the massive loss or dysfunction of cardiomyocytes caused by myocardial infarctions and hypertension. Due to the limited regenerative capacity of the heart, much research has focused on better understanding the process of differentiation towards cardiomyocytes. This review will highlight what is currently known about cardiac cell specification during mammalian development, areas of controversy, cellular sources of cardiomyocytes, and current and potential uses of stem cell derived cardiomyocytes for cardiac therapies.
Embryonic Stem Cells (ESCs) hold great potential for regeneration of dam‐ aged myocardium, howeve... more Embryonic Stem Cells (ESCs) hold great potential for regeneration of dam‐ aged myocardium, however the molecular circuitry that guides ESC differ‐ entiation into cardiomyocytes remains poorly understood. This is exempli‐ fied by the elusive role of the transcription factor, Foxc1, during cardiac development. The only known Foxc1 target during heart development is Tbx1. Because Foxc1 null mice contain heart mutations that are far more severe than Tbx1 null mice, it is likely that Foxc1 has additional regulatory roles during heart development. The goal of our study was to test whether Foxc1 is critical for ESC differentiation into functional cardiomyocytes through proper regulation of specific downstream gene networks. Con‐ verging evidence from Foxc1 deficient and overexpression ESC models re‐ veals a close relationship between Foxc1 levels and early cardiomyogenic factors Isl1, Mef2c, and Nkx2.5 and also the production of functional cardi‐ omyocytes. We show Foxc1 regulates early cardiomyogenesis during a spe‐ cific window of differentiation, D4‐D6. Through whole transcriptome RNA‐ sequencing analysis, we report pathways regulated by Foxc1 involved in cardiac function including actin cytoskeleton, cell adhesion, tight and gap junctions, and calcium signaling. Our data indicate a novel Foxc1 direct gene target, Myh7, which encodes the predominant myosin heavy chain isoform, MHCβ, expressed during cardiac development. These data lead us to conclude that Foxc1 regulates both early cardiomyogenesis and the functional properties of ESC‐derived cardiomyocytes. Our findings shed light on the molecular circuitry governing cardiomyogenesis that may lead to the development of better translational strategies for the use of pluripo‐ tent stem cells in regenerative medicine towards repairing damaged myo‐ cardium.STEM CELLS 2015; 00:000–000 SIGNIFICANCE STATEMENT: Heart attacks and high blood pressure cause death of cardiomyocytes (CMs), the cells of the heart that are required to communicate together allowing the heart to contract and relax. CMs have a very low capacity to regenerate and therefore many studies have focused attention on embryonic stem cells (ESCs) as a source of CMs to regenerate the heart. However the mechanisms that guide ESCs to become CMs are not fully understood. Our study has identified a factor that enhances the production of CMs from ESCs. Addi‐
Epigenetic and chromatin modifications play particularly important roles in Embryonic and induced... more Epigenetic and chromatin modifications play particularly important roles in Embryonic and induced Pluripotent Stem cells (ES and iPS cells) allowing for the cells to both differentiate and dedifferentiate back to a pluripotent state. We analyzed how the loss of a key chromatin modifying enzyme, histone deacetylase 1(HDAC1), affects early and cardiovascular differentiation of both ES and iPS cells. We also investigated potential differences between these two cell types when differentiation is induced. Our data indicates an essential role for HDAC1 in deacetylating regulatory regions of key pluripotency-associated genes during early differentiation. Although HDAC1 functions primarily as a histone deacetylase, its loss also affects DNA methylation in ES and iPS cells both during pluripotency and differentiation. We show that HDAC1 plays a crucial, non-redundant role in cardiomyocyte differentiation and maturation. Our data also elucidates important differences between ES and iPS cells, when levels of this enzyme are reduced, that affect their ability to differentiate into functional cardiomyocytes. As varying levels of chromatin modifying enzymes are likely to exist in patient derived iPS cells, understanding the molecular circuitry of these enzymes in ES and iPS cells is critical for their potential use in cardiovascular therapeutic applications.
Embryonic Stem Cells not only hold a lot of potential for use in regenerative medicine, but also ... more Embryonic Stem Cells not only hold a lot of potential for use in regenerative medicine, but also provide an elegant and efficient way to study specific developmental processes and pathways in mammals when whole animal gene knock out experiments fail. We have investigated a pathway through which HDAC1 affects cardiovascular and more specifically cardiomyocyte differentiation in ES cells by controlling expression of SOX17 and BMP2 during early differentiation. This data explains current discrepancies in the role of HDAC1 in cardiovascular differentiation and sheds light into a new pathway through which ES cells determine cardiovascular cell fate. Citation: Hoxha E, Lambers E, Wasserstrom JA, Mackie A, Ramirez V, et al. (2012) Elucidation of a Novel Pathway through Which HDAC1 Controls Cardiomyocyte Differentiation through Expression of SOX-17 and BMP2. PLoS ONE 7(9): e45046.
Background-Inflammation plays a critical role in adverse cardiac remodeling and heart failure. Th... more Background-Inflammation plays a critical role in adverse cardiac remodeling and heart failure. Therefore, approaches geared towards inhibiting inflammation may provide therapeutic benefits. We tested the hypothesis that genetic deletion of interleukin-10 (IL10), a potent anti-inflammatory cytokine, exacerbates pressure-overload induced adverse cardiac remodeling and hypertrophy and that IL10 therapy inhibits this pathology.
Bone-marrow endothelial progenitor cell based therapies (BM-EPC) improve the symptoms in patients... more Bone-marrow endothelial progenitor cell based therapies (BM-EPC) improve the symptoms in patients with ischemic heart disease their limited plasticity and decreased function in patients with existing heart disease limits the full benefit of EPC therapy for cardiac regenerative medicine.
Telomere homolog oligonucleotides (T-oligos) activate an innate telomere-based program that leads... more Telomere homolog oligonucleotides (T-oligos) activate an innate telomere-based program that leads to multiple anticancer effects. T-oligos act at telomeres to initiate signaling through the Werner protein and ATM kinase. We wanted to determine if T-oligos have antiangiogenic effects. We found that T-oligo-treated human melanoma (MM-AN) cells had decreased expression of vascular endothelial growth factor (VEGF), VEGF receptor 2, angiopoeitin-1 and -2 and decreased VEGF secretion. T-oligos activated the transcription factor E2F1 and inhibited the activity of the angiogenic transcription factor, HIF-1α. T-oligos inhibited EC tubulogenesis and total tumor microvascular density matrix invasion by MM-AN cells and ECs in vitro. In melanoma SCID xenografts, two systemic T-oligo injections decreased by 60% (P < .004) total tumor microvascular density and the functional vessels density by 80% (P < .002). These findings suggest that restriction of tumor angiogenesis is among the host's innate telomere-based anticancer responses and provide further evidence that T-oligos may offer a powerful new approach for melanoma treatment.
Prolonged inflammatory response is associated with left ventricular (LV) dysfunction and adverse ... more Prolonged inflammatory response is associated with left ventricular (LV) dysfunction and adverse remodeling following myocardial infarction (MI). IL-10 inhibits inflammation by suppressing HuR-mediated mRNA stabilization of proinflammatory cytokines. Here we report that following MI, IL-10 ؊/؊ mice showed exaggerated LV dysfunction, fibrosis, and cardiomyocyte apoptosis. Short-hairpin RNA (shRNA)-mediated knockdown of HuR in the myocardium significantly reversed MI-induced LV dysfunctions and LV remodeling. HuR knockdown significantly reduced MI-induced cardiomyocyte apoptosis concomitant with reduced p53 expression. Moreover, HuR knockdown significantly reduced infarct size and fibrosis area, which in turn was associated with decreased TGF- expression. In vitro, stable knockdown of HuR in mouse macrophage cell line RAW 264.7 corroborated in vivo data and revealed reduced mRNA expression of TNF-␣, TGF-, and p53 following LPS challenge, which was associated with a marked reduction in the mRNA stability of these genes. Taken together, our studies suggest that HuR is a direct target of IL-10, and HuR knockdown mimics anti-inflammatory effects of IL-10.-Krishnamurthy, P., Lambers, E., Verma, S., Thorne, T., Qin, G., Losordo, D. W., Kishore, R. Myocardial knockdown of mRNA-stabilizing protein HuR attenuates post-MI inflammatory response and left ventricular dysfunction in IL-10-null mice. FASEB J. 24, 2484 -2494 (2010). www.fasebj.org
Rationale-Endothelial progenitor cell (EPC) survival and function in the injured myocardium is ad... more Rationale-Endothelial progenitor cell (EPC) survival and function in the injured myocardium is adversely influenced by hostile microenvironment like ischemia, hypoxia and inflammatory response, thereby compromising full benefits of EPC-mediated myocardial repair.
Persistent inflammatory response has adverse effects on left ventricular (LV) function and remode... more Persistent inflammatory response has adverse effects on left ventricular (LV) function and remodeling following acute myocardial infarction (AMI). We hypothesized that suppression of inflammation with IL-10 treatment attenuates LV dysfunction and remodeling after AMI. After the induction of AMI, mice were treated with either saline or recombinant IL-10, and inflammatory response and LV functional and structural remodeling changes were evaluated. IL-10 significantly suppressed infiltration of inflammatory cells and expression of inflammatory cytokines in the myocardium. These changes were associated with IL-10-mediated inhibition of p38 MAP kinase activation and repression of cytokine mRNA stabilizing protein, HuR. IL-10 treatment significantly improved LV functions, reduced infarct size and attenuated infarct wall thinning. MI-induced increase in MMP9 expression and activity was associated with increased fibrosis since IL-10 treatment reduced both MMP9 activity and fibrosis. siRNA knockdown of HuR mimicked IL-10 mediated reduction in MMP-9 expression and activity in NIH3T3 cells. Moreover, IL-10 treatment significantly increased capillary density in the infarcted myocardium which was associated with enhanced STAT3 phosphorylation. Taken together, our studies demonstrate that IL-10 suppresses inflammatory response and contributes to improved LV function and remodeling by inhibiting fibrosis via suppression of HuR/MMP9 and by enhancing capillary density through activation of STAT3.
Neovascularization is critical for tumor growth and development. The cellular mediators for this ... more Neovascularization is critical for tumor growth and development. The cellular mediators for this process are yet to be defined. We discovered that bone marrow-derived endothelial progenitor cells (BM-EPC), having the phenotype (CD133+, CD34+, VEGFR-2+), initiate neovascularization in response to TG1-1 mammary cells implanted in the inguinal mammary gland of Tie-2 GFP transgenic mice. The fluorescence tag allowed for tracing the migration of green fluorescent protein-tagged endothelial progenitor cells to tumor tissues. We discovered that 17-B estradiol supplementation of ovariectomized mice significantly enhanced BM-EPC-induced neovascularization and secretion of angiogenic factors within the tumor microenvironment. Cell-based system analyses showed that estrogen-stimulated BM-EPCs secreted paracrine factors which enhanced TG1-1 cell proliferation and migration. Furthermore, TG1-1 cell medium supplemented with estrogeninduced BM-EPC mediated tubulogenesis, which was an experimental in vivo representation of the neovasculature. Our data provide evidence of BM-EPC mammary tumor cell interactions and identify a novel cellular mediator of tumor progression that can be exploited clinically. [Cancer Res 2008;68(15):6038-42]
The oocyte-independent source for the generation of pluripotent stem cells is one of the ultimate... more The oocyte-independent source for the generation of pluripotent stem cells is one of the ultimate goals in regenerative medicine. We report that upon exposure to mouse ES cell (ESC) extracts, reversibly permeabilized NIH3T3 cells undergo de-differentiation followed by stimulus-induced redifferentiation into multiple lineage cell types. Genome-wide expression profiling revealed significant differences between NIH3T3 control and ESC extract treated NIH3T3 cells including the re-activation of ESC specific transcripts. Epigenetically, ESC extracts induced CpG de-methylation of Oct4 promoter, hyper-acetylation of histones 3 and 4 and decreased lysine 9 (K-9) dimethylation of histone 3. In mouse models of surgically-induced hind limb ischemia (HLI) or acute myocardial infarction (AMI) transplantation of reprogrammed NIH3T3 cells significantly improved post-injury physiological functions and showed anatomical evidence of engraftment and trans-differentiation into skeletal muscle, endothelial cell and cardiomyocytes. These data provide evidence for the generation of functional multi-potent stem like cells from terminally differentiated somatic cells without the introduction of retroviral mediated trans-genes or ESC fusion.
Pluripotent embryonic stem (ES) cell therapy may be an attractive source for postinfarction myoca... more Pluripotent embryonic stem (ES) cell therapy may be an attractive source for postinfarction myocardial repair and regeneration. However, the specific stimuli and signal pathways that may control ES cell-mediated cardiomyogenesis remains to be completely defined. The aim of the present study was to investigate (1) the effect and underlying signal transduction pathways of leukemia inhibitory factor (LIF) and bone-morphogenic protein-2 (BMP-2)-induced mouse ES cell (mES-D3 line) differentiation into cardiomyocytes (CMC) and (2) the efficacy of CMC precommitted mES cells for functional and anatomical cardiac repair in surgically-induced mouse acute myocardial infarction (AMI) model. Various doses of LIF and BMP-2 and their inhibitors or blocking antibodies were tested for mES differentiation to CMC in vitro. CMC differentiation was assessed by mRNA and protein expression of CMC-specific markers, Connexin-43, CTI, CTT, Mef2c, Tbx5, Nkx2.5, GATA-4, and ␣MHC. LIF and BMP-2 synergistically induced the expression of CMC markers as early as 2 to 4 days in culture. Signaling studies identified STAT3 and MAP kinase (ERK1/2) as specific signaling components of LIFϩBMP-2-mediated CMC differentiation. Inhibition of either STAT3 or MAPK activation by specific inhibitors drastically suppressed LIFϩBMP-2-mediated CMC differentiation. Moreover, in mouse AMI, transplantation of lentivirus-GFP-transduced, LIFϩBMP-2 precommitted mES cells, improved post-MI left ventricular functions, and enhanced capillary density. Transplanted cells engrafted in myocardium and differentiated into CMC and endothelial cells. Our data suggest that LIF and BMP-2 may synergistically enhance CMC differentiation of transplanted stem cells. Thus augmentation of LIF/BMP-2 downstream signaling components or cell type specific precommitment may facilitate the effects of ES cell-based therapies for post-MI myocardial repair and regeneration. (Circ Res. 2007;101:910-918.)
Conference Presentations by Erin Lambers
Background: Embryonic Stem Cells (ESCs) hold great potential for regeneration of damaged myocardi... more Background: Embryonic Stem Cells (ESCs) hold great potential for regeneration of damaged myocardium, however the molecular circuitry that guides ESC differentiation into cardiac lineages remains poorly understood. This is exemplified by the elusive role of the developmental transcription factor, Foxc1, during cardiac development. When one human FoxC1 allele is mutated it causes Axenfeld-Rieger syndrome characterized by ocular defects and often heart defects. Foxc1 homozygous null mice are either embryonic lethal or die soon after birth with the majority of these mice containing severe heart malformations. The only known Foxc1 target during heart development is Tbx1, a transcription factor necessary for the proper alignment of the outflow tract. Because Foxc1 null mice contain heart defects that are far more severe than Tbx1 null mice, it is likely that foxc1 has additional regulatory roles in heart development. It is unknown in which specific cell types of the heart Foxc1 functions.
Hypothesis: Foxc1 is critical for ESC differentiation into functional cardiomyocytes through the regulation of a downstream regulatory transcription network.
Methods and Results: Using a murine Nkx2.5-GFP reporter ESC line, we show that Foxc1 knockdown (KD) reduces the number of Nkx2.5+ cells upon differentiation. Foxc1 KD also reduces a panel of cardiomyocyte marker transcripts as well as inhibits the beating of embryoid bodies (EBs). On the other hand, using an inducible Foxc1 overexpression (OE) ESC line, we show that Foxc1 OE increases a panel of cardiomyocyte transcripts and enhances the number beating of EBs. Additionally, Foxc1 OE beating EBs have an enhanced spontaneous beat rate and possess functional electrophysiological properties, beating in synchrony with surrounding cardiomyocytes upon electrical stimulation. RNA-sequencing results identify over 3,000 differentially regulated transcripts after Foxc1 OE during cardiomyogenesis.
Conclusion: Both molecular and functional analyses reveal a positive correlation between Foxc1 expression level and cardiomyogenesis. Currently chromatin-immunoprecipitation sequencing is being performed to determine the direct downstream regulatory network of Foxc1 during cardiomyogenesis.
Although embryonic stem cells (ESCs) hold great promise for regeneration of the heart post myocar... more Although embryonic stem cells (ESCs) hold great promise for regeneration of the heart post myocardial infarction (MI)
due to their pluripotent potential, it is this same potential that poses risk for the formation of teratomas. Lately there
have been reports that exosomes, 30-100nm membrane bound vesicles, are not simply used by the cell to exocytose
unwanted material, but contain intact protein, mRNA, and miRNA important for intercellular communication. Here we
hypothesize that ESC derived exosomes can be used to exploit an already established mechanism to shuttle ESC content
intercellularly in a cell free system for physiological and anatomical repair of the myocardium following acute myocardial
infarction. To test our hypothesis exosomes were isolated by ultracentrifugation from equal numbers of murine ESCs or
embryonic fibroblasts (MEFs). Human umbilical cord endothelial cells treated with ESC exosomes showed increased
tube formation as compared with those treated with MEF exosomes. In vivo, using a double blinded acute myocardial
infarction model, immediately after permanent ligation of the coronary artery, mice were injected with saline, ESC
exosomes, or MEF exosomes at 3 locations in the border-zone of the left ventricle (LV). To assess the functional recovery
of the LV, echocardiographical analysis was performed at Day 7, 14, and 28 following the AMI. Mice were sacrificed at
D28 for histological assessments. LV fractional shortening, ejection fraction, and end systolic diameter measurements
demonstrate that mice treated with ESC exosomes have improved LV function compared to mice treated with control
MEF exosomes or saline alone (P<.05 for all functional parameters). Mice treated with ESC exosomes show less infarct
size and apoptosis, greater capillary density, and greater cycling of both cardiomyocytes and ckit+ stem cells. miRNA
Array analysis of ESC and MEF exosomes have revealed differential expression of select miRNAs which may be
responsible for the myocardial repair and regeneration. Taken together, these data demonstrate a novel cell free system
in which ESC exosomes can exploit the regenerative capabilities of ESCs
Talks by Erin Lambers
Cardiovascular disease is the number one cause of morbidity and mortality in the developed world.... more Cardiovascular disease is the number one cause of morbidity and mortality in the developed world. Embryonic Stem Cells (ESCs) hold great potential for regeneration of damaged myocardium, however the molecular circuitry that guides ESC differentiation into cardiac lineages remains poorly understood. This is exemplified by the elusive role of the developmental transcription factor, Foxc1, during cardiac development. When one FoxC1 allele is mutated in humans it causes Axenfeld-Rieger syndrome characterized by ocular defects and often heart defects. Foxc1 homozygous null mice are either embryonic lethal or die soon after birth with the majority of these mice containing severe heart malformations. The only known foxc1 target during heart development is tbx1, a transcription factor necessary for the proper alignment of the outflow tract. Because foxc1 null mice contain heart mutations that are far more severe than tbx1 null mice it is probable that foxc1 has additional regulatory roles in heart development. It is also unknown in which specific cell types of the heart foxc1 functions. I have recently obtained preliminary data, using ESCs, showing that knockdown of Foxc1 reduces cardiomyocyte differentiation and that overexpression of Foxc1 increases expression of cardiomyocyte transcripts and enhances beating. These data taken together, has lead to the central hypothesis that Foxc1 is critical for ESC differentiation into functional cardiomyocytes through the proper regulation of direct downstream target genes. This hypothesis will be tested with 3 Specific Aims. Aim 1 is to test the hypothesis that Foxc1 is necessary for the early differentiation of ESCs into functional cardiomyocytes. I will differentiate Nkx2.5-GFP reporter ESCs in which foxc1 has been stably knocked down with lentiviral shRNA constructs. Compared to a scramble shRNA control, cardiac differentiation will be assessed with cardiomyocyte mRNA and protein markers, in addition to quantification of Nkx2.5GFP+ cells. Function of cardiomyocytes will be assessed by quantification of beating and analysis of calcium handling. Aim2 is to test the hypothesis that overexpression of Foxc1 is sufficient to increase ESC differentiation into functional cardiomyocyte lineages. Foxc1 overexpression will be induced in ESCs containing a foxc1 doxycycline-controllable transgene. After ESC differentiation is induced in endogenous vs overexpressing foxc1 cells, I will assess cardiomyocyte differentiation and function as described above in aim 1. Aim 3 is to test the hypothesis that Foxc1 directly regulates downstream targets during ESC differentiation into cardiomyocytes. ChIP sequencing will be performed after differentiation of ESCs into cardiomyocytes to test for the direct gene targets bound by Foxc1 during early cardiac differentiation. Using luciferase assays, we will validate Foxc1 regulation of target gene expression.
Objective: To obtain congenital cardiovascular malformation (CVM) infant mortality rates (IMRs) ... more Objective: To obtain congenital cardiovascular malformation (CVM) infant mortality rates (IMRs) in Shelby County, Tennessee to better understand the causes of infant death that contribute to the high infant mortality rates in Shelby County as well as to identify maternal and infant risk factors for CVM infant death in Shelby County which could potentially lead to effective strategies to reduce CVM-related infant mortality.
Methods: A population based case control study was performed in Shelby County, TN using Matched Birth-Death Certificate records at the Shelby County Health Department from years 2004-2011. Cases (n=65) were selected on the basis of an infant dying from a cardiovascular malformation (ICD10 Codes Q20-28) before the age of 1 whose mother resided in Shelby County, Tennessee. Controls (n=114325) included all infants who survived to the age of one year whose mothers resided in Shelby County. Infants who died of other diagnostic causes were excluded from the study.
Results: CVM infant mortality rates were significantly higher in Shelby County compared to the rest of the United States population. The Shelby County and United States CMV IMRs were 5.64 and 3.70 per 10,000 live births, respectively (p<.05). Mothers who paid with Medicaid (Tenncare) were 2.04 (1.02-4.07) times more likely to have an infant die from CVM than mothers who paid with private insurance after controlling for known risk factors for CVM death including maternal age, diabetes, infection, smoking, and infant’s APGAR score in a logistic regression model. Mother’s between ages of 19-24 and >36 were 1.89 (1.03-3.48) and 2.76 (1.19-6.39) times more likely to give birth to an infant who dies from a CVM than mothers between the ages of 25-35. Infants with a 5 minute Apgar score of <7 were 17.5 (10.27-29.9) times more likely to die from a CVM than infants with an Apgar score of 7 or greater.
Conclusions: The association between payment type and CVM infant death warrants further investigation into the differences in medical coverage between Medicaid and private insurance providers to reduce the CVM IMR in Shelby County, TN.
Teaching Documents by Erin Lambers
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Papers by Erin Lambers
Conference Presentations by Erin Lambers
Hypothesis: Foxc1 is critical for ESC differentiation into functional cardiomyocytes through the regulation of a downstream regulatory transcription network.
Methods and Results: Using a murine Nkx2.5-GFP reporter ESC line, we show that Foxc1 knockdown (KD) reduces the number of Nkx2.5+ cells upon differentiation. Foxc1 KD also reduces a panel of cardiomyocyte marker transcripts as well as inhibits the beating of embryoid bodies (EBs). On the other hand, using an inducible Foxc1 overexpression (OE) ESC line, we show that Foxc1 OE increases a panel of cardiomyocyte transcripts and enhances the number beating of EBs. Additionally, Foxc1 OE beating EBs have an enhanced spontaneous beat rate and possess functional electrophysiological properties, beating in synchrony with surrounding cardiomyocytes upon electrical stimulation. RNA-sequencing results identify over 3,000 differentially regulated transcripts after Foxc1 OE during cardiomyogenesis.
Conclusion: Both molecular and functional analyses reveal a positive correlation between Foxc1 expression level and cardiomyogenesis. Currently chromatin-immunoprecipitation sequencing is being performed to determine the direct downstream regulatory network of Foxc1 during cardiomyogenesis.
due to their pluripotent potential, it is this same potential that poses risk for the formation of teratomas. Lately there
have been reports that exosomes, 30-100nm membrane bound vesicles, are not simply used by the cell to exocytose
unwanted material, but contain intact protein, mRNA, and miRNA important for intercellular communication. Here we
hypothesize that ESC derived exosomes can be used to exploit an already established mechanism to shuttle ESC content
intercellularly in a cell free system for physiological and anatomical repair of the myocardium following acute myocardial
infarction. To test our hypothesis exosomes were isolated by ultracentrifugation from equal numbers of murine ESCs or
embryonic fibroblasts (MEFs). Human umbilical cord endothelial cells treated with ESC exosomes showed increased
tube formation as compared with those treated with MEF exosomes. In vivo, using a double blinded acute myocardial
infarction model, immediately after permanent ligation of the coronary artery, mice were injected with saline, ESC
exosomes, or MEF exosomes at 3 locations in the border-zone of the left ventricle (LV). To assess the functional recovery
of the LV, echocardiographical analysis was performed at Day 7, 14, and 28 following the AMI. Mice were sacrificed at
D28 for histological assessments. LV fractional shortening, ejection fraction, and end systolic diameter measurements
demonstrate that mice treated with ESC exosomes have improved LV function compared to mice treated with control
MEF exosomes or saline alone (P<.05 for all functional parameters). Mice treated with ESC exosomes show less infarct
size and apoptosis, greater capillary density, and greater cycling of both cardiomyocytes and ckit+ stem cells. miRNA
Array analysis of ESC and MEF exosomes have revealed differential expression of select miRNAs which may be
responsible for the myocardial repair and regeneration. Taken together, these data demonstrate a novel cell free system
in which ESC exosomes can exploit the regenerative capabilities of ESCs
Talks by Erin Lambers
Methods: A population based case control study was performed in Shelby County, TN using Matched Birth-Death Certificate records at the Shelby County Health Department from years 2004-2011. Cases (n=65) were selected on the basis of an infant dying from a cardiovascular malformation (ICD10 Codes Q20-28) before the age of 1 whose mother resided in Shelby County, Tennessee. Controls (n=114325) included all infants who survived to the age of one year whose mothers resided in Shelby County. Infants who died of other diagnostic causes were excluded from the study.
Results: CVM infant mortality rates were significantly higher in Shelby County compared to the rest of the United States population. The Shelby County and United States CMV IMRs were 5.64 and 3.70 per 10,000 live births, respectively (p<.05). Mothers who paid with Medicaid (Tenncare) were 2.04 (1.02-4.07) times more likely to have an infant die from CVM than mothers who paid with private insurance after controlling for known risk factors for CVM death including maternal age, diabetes, infection, smoking, and infant’s APGAR score in a logistic regression model. Mother’s between ages of 19-24 and >36 were 1.89 (1.03-3.48) and 2.76 (1.19-6.39) times more likely to give birth to an infant who dies from a CVM than mothers between the ages of 25-35. Infants with a 5 minute Apgar score of <7 were 17.5 (10.27-29.9) times more likely to die from a CVM than infants with an Apgar score of 7 or greater.
Conclusions: The association between payment type and CVM infant death warrants further investigation into the differences in medical coverage between Medicaid and private insurance providers to reduce the CVM IMR in Shelby County, TN.
Teaching Documents by Erin Lambers
Hypothesis: Foxc1 is critical for ESC differentiation into functional cardiomyocytes through the regulation of a downstream regulatory transcription network.
Methods and Results: Using a murine Nkx2.5-GFP reporter ESC line, we show that Foxc1 knockdown (KD) reduces the number of Nkx2.5+ cells upon differentiation. Foxc1 KD also reduces a panel of cardiomyocyte marker transcripts as well as inhibits the beating of embryoid bodies (EBs). On the other hand, using an inducible Foxc1 overexpression (OE) ESC line, we show that Foxc1 OE increases a panel of cardiomyocyte transcripts and enhances the number beating of EBs. Additionally, Foxc1 OE beating EBs have an enhanced spontaneous beat rate and possess functional electrophysiological properties, beating in synchrony with surrounding cardiomyocytes upon electrical stimulation. RNA-sequencing results identify over 3,000 differentially regulated transcripts after Foxc1 OE during cardiomyogenesis.
Conclusion: Both molecular and functional analyses reveal a positive correlation between Foxc1 expression level and cardiomyogenesis. Currently chromatin-immunoprecipitation sequencing is being performed to determine the direct downstream regulatory network of Foxc1 during cardiomyogenesis.
due to their pluripotent potential, it is this same potential that poses risk for the formation of teratomas. Lately there
have been reports that exosomes, 30-100nm membrane bound vesicles, are not simply used by the cell to exocytose
unwanted material, but contain intact protein, mRNA, and miRNA important for intercellular communication. Here we
hypothesize that ESC derived exosomes can be used to exploit an already established mechanism to shuttle ESC content
intercellularly in a cell free system for physiological and anatomical repair of the myocardium following acute myocardial
infarction. To test our hypothesis exosomes were isolated by ultracentrifugation from equal numbers of murine ESCs or
embryonic fibroblasts (MEFs). Human umbilical cord endothelial cells treated with ESC exosomes showed increased
tube formation as compared with those treated with MEF exosomes. In vivo, using a double blinded acute myocardial
infarction model, immediately after permanent ligation of the coronary artery, mice were injected with saline, ESC
exosomes, or MEF exosomes at 3 locations in the border-zone of the left ventricle (LV). To assess the functional recovery
of the LV, echocardiographical analysis was performed at Day 7, 14, and 28 following the AMI. Mice were sacrificed at
D28 for histological assessments. LV fractional shortening, ejection fraction, and end systolic diameter measurements
demonstrate that mice treated with ESC exosomes have improved LV function compared to mice treated with control
MEF exosomes or saline alone (P<.05 for all functional parameters). Mice treated with ESC exosomes show less infarct
size and apoptosis, greater capillary density, and greater cycling of both cardiomyocytes and ckit+ stem cells. miRNA
Array analysis of ESC and MEF exosomes have revealed differential expression of select miRNAs which may be
responsible for the myocardial repair and regeneration. Taken together, these data demonstrate a novel cell free system
in which ESC exosomes can exploit the regenerative capabilities of ESCs
Methods: A population based case control study was performed in Shelby County, TN using Matched Birth-Death Certificate records at the Shelby County Health Department from years 2004-2011. Cases (n=65) were selected on the basis of an infant dying from a cardiovascular malformation (ICD10 Codes Q20-28) before the age of 1 whose mother resided in Shelby County, Tennessee. Controls (n=114325) included all infants who survived to the age of one year whose mothers resided in Shelby County. Infants who died of other diagnostic causes were excluded from the study.
Results: CVM infant mortality rates were significantly higher in Shelby County compared to the rest of the United States population. The Shelby County and United States CMV IMRs were 5.64 and 3.70 per 10,000 live births, respectively (p<.05). Mothers who paid with Medicaid (Tenncare) were 2.04 (1.02-4.07) times more likely to have an infant die from CVM than mothers who paid with private insurance after controlling for known risk factors for CVM death including maternal age, diabetes, infection, smoking, and infant’s APGAR score in a logistic regression model. Mother’s between ages of 19-24 and >36 were 1.89 (1.03-3.48) and 2.76 (1.19-6.39) times more likely to give birth to an infant who dies from a CVM than mothers between the ages of 25-35. Infants with a 5 minute Apgar score of <7 were 17.5 (10.27-29.9) times more likely to die from a CVM than infants with an Apgar score of 7 or greater.
Conclusions: The association between payment type and CVM infant death warrants further investigation into the differences in medical coverage between Medicaid and private insurance providers to reduce the CVM IMR in Shelby County, TN.