Number Of Very Small Embryonic-like Stem Cells Research Articles

Positive effects of prolonged caloric restriction on the population of very small embryonic-like stem cells - hematopoietic and ovarian implications.

BackgroundLow calorie intake, or calorie restriction (CR) without malnutrition, has been demonstrated in several animal species, including mice, to increase both median and maximum lifespan as well as delay reproductive senescence. Our previous work demonstrated a positive correlation between life span and the number of very small embryonic-like stem cells (VSELs) in long living Laron dwarf mice. These animals have very low levels of circulating insulin-like growth factor 1 (IGF-1) in peripheral blood (PB), maintain higher numbers of hematopoietic stem cells (HSPCs) in bone marrow (BM), and display prolonged fecundity compared with wild type littermates. Since CR lowers the level of IGF-1 in PB, we become interested in the effect of CR on the number of VSELs and HSPCs in BM as well as on the morphology of ovaries and testes.MethodsIn our studies four-week-old female and male mice were subjected to CR by employing an alternate-day ad libitum feeding diet for a period of 9 months.ResultsWe observed that mice on CR had a higher number of BM-residing VSELs than control mice fed ad libitum. These changes correlated with higher numbers of HSPCs in BM, spleen, and peripheral blood (PB) as well as with an increase in the number of primordial and primary follicles in ovaries. At the same time, however, no changes were observed in the testes of mice under CR.ConclusionWe conclude that CR positively affects the pool of VSELs in adult tissues and explains the positive effect of CR on longevity.

Novel View on Stem Cell Compartment and Aging - a Number of Pluripotent Very Small Embryonic Like Stem Cells and Hematopoietic Stem Cells in Murine Bone Marrow Is High in Several Long-Living and Reduced in Short-Living Murine Strains and Unexpectedly Inversely Correlates in These Animals with Plasma Growth Hormone/Insulin-Like Growth Factor-1 Level

Abstract LBA-5 Background:It is known that an increase in caloric intake leads to increase in plasma growth hormone (GH) level that subsequently induces secretion of insulin-like growth factor-1 (IGF-1) from liver, what leads to accelerated aging (Nature 2010;464:504). On the other hand, caloric restriction and a resulting decrease in plasma IGF-1 level has the opposite effect and extends lifespan. It also known that adult tissues contain a population of pluripotent very small embryonic like stem cells (VSELs) that play as postulated an important role in rejuvenation of long term hematopoietic stem cells (LT-HSCs) in bone marrow (BM) Leukemia 2011; doi:10.1038/leu.2011.73, Exp. Hematology 2011;39:225–237). As we observed previously, the number of these cells in murine BM decreases with age and VSELs are kept quiescent in BM and protected from premature depletion by erasure of the somatic imprint in differentially methylated regions (DMRs) of some paternally imprinted genes involved in insulin/insulin growth factors signaling (IIS) such as e.g., Igf2-H19 and RasGRF1 (Leukemia 2009;23:2042). Hypothesis:To explain and connect these phenomena together, we hypothesized that prolonged insulin/insulin growth factors signaling (IIS) prematurely depletes VSELs from the adult tissues and in BM may negatively impact on population of HSCs. Material and Methods:The number of VSELs and HSCs in long living murine strains with inborn low level of circulating IGF-1 (Laron- and Ames- dwarfs) as well as in short living mice with high levels of circulating IGF-1 (e.g., transgenic mice that overexpress bovine growth hormone; bGH) was evaluated by FACS. VSELs were isolated and epigenetic status of genes regulating pluripotency (e.g., Oct-4) as well as imprinted genes regulating IIS was evaluated by employing bisulfate modification of DNA followed by sequencing and by COBRE assay. We also challenged long living mice with low IGF-1 plasma level by daily injections of recombinant GH or IGF-1. Results:We found that the number of VSELs and HSCs residing in BM inversely correlates with plasma GH/IGF-1 level. To support this, mice with low circulating plasma IGF-1 levels (Laron- and Ames-dwarf mice) have higher numbers of VSELs and HSCs in BM that, in contrast to aged-matched normal littermates, are maintained at high levels even into advanced age. The analysis of molecular signature of VSELs in these animals revealed prolonged retention of hypomethylation in the DMRs within the Igf2-H19 and RasGRF1 loci, which attenuates IIS signaling in these cells. The number of VSELs, however, decreased in these animals after prolonged treatment with GH or recombinant IGF-I. Conversely, mice with elevated IGF-I level in plasma due to expression of the GH transgene or normal wild type mice injected for a sustained period with recombinant GH both exhibit significant decreases in the number of VSELs and HSCs in BM compared to control animals. These decreases were paralleled by epigenetic changes in Igf2-H19 and RasGRF1 loci in which DMRs became hypermethylated over time. These changes in methylation lead to increases in IGF-2 and RasGRF1 expression and may explain why GH transgenic mice have an increase in IIS that leads to shortening of life span in these animals. Conclusions:Our data shed new light on the relationships between senescence, GH/IGF-1 level, prolonged IIS, and number of VSELs and LT-HSCs. Accordingly, we propose a new paradigm in which a decrease in IIS (e.g., due to caloric restriction that lowers plasma IGF-1 level) may delay the age-dependent elimination of VSELs from adult tissues. By contrast, chronic IIS (e.g., due to chronic high caloric intake and the resulting elevated GH and IGF-1 levels) prematurely depletes VSELs residing in adult organs, which for example in BM leads to a decrease in the number of LT-HSCs. This study also indicates that GH-based anti-aging therapies need careful re-evaluation of their potentially uncontrolled stimulation of VSELs in BM that may lead to development of hematological malignancies. In support of this, elevated GH and IIS lead to hematological malignancies, while, by contrast, Laron dwarf mice and Laron dwarf patients, which have a low plasma IGF-1 levels, do not develop leukemias. Disclosures:Ratajczak:Neostem Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Novel View on Stem Cell Compartment and Aging - a Number of Pluripotent Very Small Embryonic Like Stem Cells and Hematopoietic Stem Cells in Murine Bone Marrow Is High in Several Long-Living and Reduced in Short-Living Murine Strains and Unexpectedly Inversely Correlates in These Animals with Plasma Growth Hormone/Insulin-Like Growth Factor-1 Level

Abstract LBA-5 Background: It is known that an increase in caloric intake leads to increase in plasma growth hormone (GH) level that subsequently induces secretion of insulin-like growth factor-1 (IGF-1) from liver, what leads to accelerated aging (Nature 2010;464:504). On the other hand, caloric restriction and a resulting decrease in plasma IGF-1 level has the opposite effect and extends lifespan. It also known that adult tissues contain a population of pluripotent very small embryonic like stem cells (VSELs) that play as postulated an important role in rejuvenation of long term hematopoietic stem cells (LT-HSCs) in bone marrow (BM) Leukemia 2011; doi:10.1038/leu.2011.73, Exp. Hematology 2011;39:225–237). As we observed previously, the number of these cells in murine BM decreases with age and VSELs are kept quiescent in BM and protected from premature depletion by erasure of the somatic imprint in differentially methylated regions (DMRs) of some paternally imprinted genes involved in insulin/insulin growth factors signaling (IIS) such as e.g., Igf2-H19 and RasGRF1 (Leukemia 2009;23:2042). Hypothesis: To explain and connect these phenomena together, we hypothesized that prolonged insulin/insulin growth factors signaling (IIS) prematurely depletes VSELs from the adult tissues and in BM may negatively impact on population of HSCs. Material and Methods: The number of VSELs and HSCs in long living murine strains with inborn low level of circulating IGF-1 (Laron- and Ames- dwarfs) as well as in short living mice with high levels of circulating IGF-1 (e.g., transgenic mice that overexpress bovine growth hormone; bGH) was evaluated by FACS. VSELs were isolated and epigenetic status of genes regulating pluripotency (e.g., Oct-4) as well as imprinted genes regulating IIS was evaluated by employing bisulfate modification of DNA followed by sequencing and by COBRE assay. We also challenged long living mice with low IGF-1 plasma level by daily injections of recombinant GH or IGF-1. Results: We found that the number of VSELs and HSCs residing in BM inversely correlates with plasma GH/IGF-1 level. To support this, mice with low circulating plasma IGF-1 levels (Laron- and Ames-dwarf mice) have higher numbers of VSELs and HSCs in BM that, in contrast to aged-matched normal littermates, are maintained at high levels even into advanced age. The analysis of molecular signature of VSELs in these animals revealed prolonged retention of hypomethylation in the DMRs within the Igf2-H19 and RasGRF1 loci, which attenuates IIS signaling in these cells. The number of VSELs, however, decreased in these animals after prolonged treatment with GH or recombinant IGF-I. Conversely, mice with elevated IGF-I level in plasma due to expression of the GH transgene or normal wild type mice injected for a sustained period with recombinant GH both exhibit significant decreases in the number of VSELs and HSCs in BM compared to control animals. These decreases were paralleled by epigenetic changes in Igf2-H19 and RasGRF1 loci in which DMRs became hypermethylated over time. These changes in methylation lead to increases in IGF-2 and RasGRF1 expression and may explain why GH transgenic mice have an increase in IIS that leads to shortening of life span in these animals. Conclusions: Our data shed new light on the relationships between senescence, GH/IGF-1 level, prolonged IIS, and number of VSELs and LT-HSCs. Accordingly, we propose a new paradigm in which a decrease in IIS (e.g., due to caloric restriction that lowers plasma IGF-1 level) may delay the age-dependent elimination of VSELs from adult tissues. By contrast, chronic IIS (e.g., due to chronic high caloric intake and the resulting elevated GH and IGF-1 levels) prematurely depletes VSELs residing in adult organs, which for example in BM leads to a decrease in the number of LT-HSCs. This study also indicates that GH-based anti-aging therapies need careful re-evaluation of their potentially uncontrolled stimulation of VSELs in BM that may lead to development of hematological malignancies. In support of this, elevated GH and IIS lead to hematological malignancies, while, by contrast, Laron dwarf mice and Laron dwarf patients, which have a low plasma IGF-1 levels, do not develop leukemias. Disclosures: Ratajczak: Neostem Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees.

A Novel Perspective on Stem Cells, Tissue Senescence and Aging: Pluripotent Very Small Embryonic-Like Stem Cells (VSELs) and Hematopoietic Stem Cells (HSCs) Are Prematurely Depleted in Adult Bone Marrow (BM) in Response to Prolonged Growth Hormone/Insulin-Like Growth Factor-1 Signaling (IIS) and Chronic Increase in Caloric Uptake

Abstract 4818 Background.Caloric uptake elevates the plasma level of growth hormone (GH), which subsequently stimulates release of insulin-like growth factor-1 (IGF-1) from the liver. Evidence is accumulating that an increase in caloric intake, which leads to prolonged growth hormone (GH) and insulin/insulin-like growth factors signaling (IIS), accelerates aging. On the other hand, caloric restriction and a resulting decrease in IIS has the opposite effect and extends lifespan (Nature 2010;464:504). In support of this finding, mice with low circulating IGF-1 levels (Laron, Ames, and Snell dwarfs) live much longer than their normal littermates and, conversely, mice with high levels of circulating IGF-1 (e.g., transgenic mice that overexpress bovine growth hormone [bGH]) have significantly reduced life span. Aim of Hypothesis.To explain these phenomena, we hypothesized that prolonged IIS prematurely depletes adult tissues of very small embryonic-like stem cells (VSELs), which are the most developmentally primitive adult tissue-residing pluripotent stem cells (Leukemia 2006;20:857). We envision that VSELs play an important role in rejuvenation of the pool of tissue-committed stem cells and, as we observed previously, the number of these cells in murine BM decreases with age. We demonstrated that in bone marrow (BM), VSELs give rise to long-term repopulating hematopoietic stem cells (LT-HSCs) (Leukemia 2011; doi:10.1038/leu.2011.73, Exp. Hematology 2011;39:225–237). As previously reported, VSELs are kept quiescent in BM and protected from premature depletion by erasure of the somatic imprint in differentially methylated regions (DMRs) of some paternally imprinted genes involved in IIS (e.g., Igf2-H19 and RasGRF1). Results.In the current study, we provide direct evidence that the number of VSELs deposited in BM during ontogenesis is related to plasma IIS signaling, which is affected by the GH/IGF-1 level. In particular, mice with elevated IGF-I level in plasma due to expression of the bovine GH transgene and wild type mice injected for a sustained period with porcine GH both exhibit significant decreases in the number of VSELs and HSCs in BM compared to control animals. These decreases were paralleled by epigenetic changes in Igf2-H19 and RasGRF1 loci in which DMRs became hypermethylated over time. These changes in methylation lead to increases in IGF-2 and RasGRF1 expression and may explain why bovine GH transgenic mice have an increase in IIS and a significantly reduced life span. Conversely, mice with low circulating plasma IGF-1 levels (Laron and Ames dwarf mice ) have higher numbers of VSELs and HSCs in BM that, in contrast to aged-matched normal littermates, are maintained at high levels even into advanced age. The molecular signature of VSELs in these animals revealed prolonged retention of hypomethylation in the DMRs within the Igf2-H19 and RasGRF1 loci, which attenuated IIS signaling in these cells. The number of VSELs, however, decreased in these animals after prolonged treatment with porcine GH or human recombinant IGF-I. Conclusions.Our data shed new light on the relationships between senescence, high GH level, prolonged IIS, and depletion of VSELs and LT-HSCs. Accordingly, we propose a new paradigm in which chronic IIS (e.g., due to chronic high caloric intake and the resulting elevated GH and IGF-1 levels) prematurely depletes VSELs in BM, which leads to a decrease in the number of LT-HSCs. By contrast, caloric restriction and a decrease in IIS may delay the age-dependent elimination of VSELs from BM. This study also indicates that GH-based anti-aging therapies need careful re-evaluation of their potentially uncontrolled stimulation of VSELs in BM and downstream effects on hematopoiesis and the development of hematological malignancies. In support of this concern, elevated IIS may lead to hematological malignancies (uncontrolled proliferation of VSELs), while, by contrast, it is known that Laron dwarf mice and Laron dwarf patients, which have a GH-receptor deficiency and low plasma IGF-1 levels, do not develop leukemias. Disclosures:Ratajczak:Neostem Inc: Consultancy, Research Funding.

The Number of Very Small Embryonic Like Stem Cells (VSELs) Decreases During Aging In An IGF-1-Dependent Manner - a Novel Link Between Aging, Caloric Restriction, and the Size of the Stem Cell Pool

AbstractAbstract 4796We have previously demonstrated the presence of very small (smaller than erythrocytes) Oct-4+SSEA-1+Sca-1+Lin-CD45- VSELs in bone marrow (BM) and in several murine adult organs (Leukemia 2006;20:857 and Cytometry 2009;73:1116). These small cells i) have large nuclei that contain primitive open chromatin, ii) express Oct-4 gene (as confirmed by our recent promoter methylation and chromatin structure analysis studies), and iii) posses bivalent domain-marked promoter regions of homeodomain-containing developmental master transcription factors, such as Dlx-, Irx-, Lhx-, Pou-, Pax-, and Six-family proteins. Furthermore, the epigenetic changes in selected somatic-imprinted genes (e.g., Igf2-H19 and RasGrf1) involved in insulin-factor signaling (Igf-1, Igf-2, and Insulin) govern their quiescent state, thus preventing them from unleashing proliferation and spontaneous growth of teratomas (Leukemia 2009;23:2042). O other hand it is well known that i) Igf-1 signaling negatively regulates lifespan in worms, flies, and mammals (Cell 2005;120:449) and that ii) Igf-1 and insulin levels in blood are positively regulated by caloric uptake. Indeed, we found that the pool size and pluripotentiality of VSELs decreases during aging. Accordingly, in our studies performed on young (4-week-old) and old (2-year-old) mice we found that i) the number of VSELs and their pluripotentiality decreases with age, ii) VSELs from old mice show lower expression of Oct-4, Nanog, Sox2, Klf4, and cMyc, iii) the Oct-4 promoter becomes hypermethylated with age and has a closed chromatin structure, iv) VSELs from old mice show somatic methylation in both Igf2-H19 and Rasgrf1 loci, and v), as a result, VSELs from these mice have increased sensitivity to insulin/insulin factors signaling. This suggests that chronic insulin receptor/Igf-1 receptor signaling in VSELs may contribute to age-related depletion of these cells. To explain better the role of insulin signaling in VSELs, we measured by FACS the number of VSELs in murine Laron dwarfs, which exhibit chronic Igf-1 deficiency and, as a result, live 30–40% longer than their normal littermates. We report here, for the first time, that the number of VSELs in the BM of Igf-1–deficient Laron dwarfs is 3–4 fold higher and is maintained at a higher level during aging compared to normal wild type (wt) littermates. Molecular analysis studies will confirm whether or not the molecular signature of VSELs in aging Laron dwarfs is somehow protected from age-related changes (e.g., by the methylation status of the Oct-4 promoter and/or genomic imprinted genes). Based on our data, we postulate novel linkages between Igf-1 level, aging, and the stem cell compartment. According to our hypothesis, early in development a population of VSELs would be deposited in developing organs as a backup for tissue-committed stem cells and play a role in rejuvenation of tissues and organ regeneration after damage. These cells would be protected from uncontrolled proliferation and age-related depletion by changes in imprinted genes that regulate insulin signaling. We further hypothesize that in the adult body the pool of VSEL cells is regulated by the circulating Igf-1 level. An increase in Igf-1 level (e.g., resulting from a chronically high calorie diet) would accelerate an age-dependent decrease in VSELs and their potential to rejuvenate tissues. By contrast, a low Igf-1 level (e.g., as seen in Laron dwarf mutants or due to caloric restriction) would have a protective effect on the overall pool of these cells. Thus, we present for the first time a hypothesis that reconciles aging, longevity, Igf-1 signaling, and caloric uptake and negative effect of Igf-1 and high calorie uptake on number/function of pluripotent VSELs deposited in adult tissues. Disclosures:No relevant conflicts of interest to declare.