Mesenchymal stromal cells (MSC) are bone marrow-derived, non-hematopoietic progenitors that are amenable to genetic engineering, making them attractive delivery vehicles for therapeutic proteins. However, limited transplanted cell survival compromises the efficacy of MSC-based gene therapy. We hypothesized that co-implantation of insulin-like growth factor-1 (IGF-I)-overexpressing MSC (MSC-IGF) would improve MSC-based therapy of anemia by providing paracrine support to erythropoietin (EPO)-secreting MSC (MSC-EPO). Murine MSC were found to express the IGF-I receptor and be responsive to IGF-I stimulation. IGF-I also improved MSC survival in vitro. MSC were admixed in a bovine collagen matrix and implanted by subcutaneous injection in a murine model of chronic renal failure. Mice receiving MSC-EPO co-implanted with MSC-IGF experienced a greater and significantly sustained elevation in hematocrit compared to controls; heart function was also improved. Co-implantation of MSC-IGF therefore represents a promising new strategy for enhancing implanted cell survival, and improving cell-based gene therapy of renal anemia.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed Oct. 13, 2008). Includes bibliographical references (p. 56-64).

A leishmaniose visceral é uma infecção grave que leva a pancitopenia. Quando se trata de disfunções medulares decorrentes de infecção por Leishmania (Leishmania) infantum há poucas abordagens descrevendo as alterações na mielopoiese e os mecanismos que levam a pancitopenia na LV. Alguns estudos demonstram uma relação importante entre a pancitopenia e o fator de crescimento insulin-like growth fator-I (IGF-I), no entanto, o seu papel endógeno na hematopoiese ainda não está claro. Propomos estudar a influência desse fator na hematopoiese e sua relação com o desenvolvimento da pancitopenia em hamsteres infectados por via intra-peritoneal com 2x107 de amastigotas por L. (L.) infantum. Avaliamos em 90 e 120 dias pós-infecção a LDU (Leishman-Donovan units) no baço e fígado, quando observamos tendência à progressão da infecção. Aos 60 dias pós-infecção, os animais com LV desenvolveram a plaquetopenia como primeira alteração hematológica, e a partir dos 90 dias pós-infecção, a anemia, e a leucopenia com reduções significantes nos leucócitos totais, linfócitos e neutrófilos. Já aos 120 dias de infecção, os leucócitos totais diminuíram significantemente acompanhados por uma redução de linfócitos, monócitos e eosinófilos. A partir desses dados, focamos a análise da medula óssea nos hamsteres com 90 e 120 pós-infecção. No mielograma, vimos alterações somente nos hamsteres com LV aos 90 dias pós-infecção, com um aumento significante na proporção células mielóides imaturas: células mielóides maduras. Na biópsia da tíbia, houve um aumento significante da celularidade quando comparados com seu respectivo controle, apenas no período de 90 dias pós-infecção. Em adição, observamos uma proliferação e/ou infiltrado macrofágico significante nos hamsteres com LV, mas sem diferença estatística nos períodos de 90 e 120 dias pós-infecção. Na avaliação semi-quantitativa de fibras de reticulina, somente aos 90 dias pós-infecção, observamos aumento significante nos infectados comparados aos controles, caracterizando um quadro fibrótico. Foi medida a expressão de mRNA de IGF-I por PCR em tempo real, aos 90 e 120 dias pós-infecção, onde ocorreu um aumento significante da expressão de IGF-I nos animais infectados em relação aos controles aos 90 dias. Como expostos, os hamsteres com LV apresentam alterações hematológicas como anemia, leucopenia e plaquetopenia, e ainda alterações na medula óssea como aumento da celularidade, proliferação macrofágica e fibrose acompanhados por um aumento da expressão de IGF-I. Assim podemos concluir que nossos dados indicam que o hamster se constitui num bom modelo para o estudo da patogênese da pancitopenia e das alterações medulares decorrentes da infecção por L.(L.) infantum. Neste modelo, ocorre alteração da expressão de IGF-I durante a evolução da infecção com possível papel na patogenia da pancitopenia. / Visceral leishmaniasis is a serious infection that leads to pancytopenia. When it comes to spinal cord dysfunction resulting from infection Leishmania (Leishmania) infantum there are few approaches describing the changes in myelopoiesis and mechanisms that lead to pancytopenia in LV. Some studies have shown a significant relationship between pancytopenia and insulin-like growth factor-growth factor I (IGF-I), however, their endogenous role in hematopoiesis is still not clear. We propose to study the influence of this factor in hematopoiesis and its relationship to the development of pancytopenia in hamsters infected intraperitoneally with 2x107 amastigotes by L. (L.) infantum. Evaluated at 90 and 120 days post-infection the LDU (Leishman-Donovan units) in the spleen and liver, when we observed a tendency to progression of the infection. At 60 days post-infection, animals with LV developed thrombocytopenia as the first hematologic changes, and from 90 days post-infection, anemia, and leukopenia with significant reductions in total leukocytes, lymphocytes and neutrophils. Already at 120 days of infection, total leukocytes decreased significantly accompanied by a decrease lymphocytes, monocytes and eosinophils. From these data, we focus on the analysis of the bone marrow in hamsters with 90 and 120 post-infection. The myelogram changes seen only in hamsters with LV at 90 days post-infection, with a significant increase in the proportion immature myeloid cells: mature myeloid cells. Biopsy of the tibia, there was a significant increase in cellularity compared with their respective control, only 90 days post-infection. In addition, we observed a proliferation and / or infiltration significant macrophage in hamsters with LV, but no statistical difference in the periods of 90 and 120 days post-infection. In semi-quantitative assessment of reticulin fibers, only at 90 days post-infection, we observed a significant increase in infected compared to controls, featuring a fibrous framework. MRNA expression of IGF-I was measured by real-time PCR, at 90 and 120 days post-infection, where a significant increase in IGF-I expression in infected animals compared to controls at 90 days occurred. As set out, the present hamsters VL hematological disorders such as anemia, leukopenia and thrombocytopenia, as well as changes in bone marrow cellularity increased, macrophage proliferation and fibrosis accompanied by a reduction in IGF-I expression. Thus we can conclude that our data indicate that the hamster is a good model to study the pathogenesis of pancytopenia and marrow changes resulting from infection by L. (L.) Infantum. In this model, alteration of IGF-I expression during the course of infection with a possible role in the pathogenesis of pancytopenia.

A leishmaniose visceral é uma infecção grave que leva a pancitopenia. Quando se trata de disfunções medulares decorrentes de infecção por Leishmania (Leishmania) infantum há poucas abordagens descrevendo as alterações na mielopoiese e os mecanismos que levam a pancitopenia na LV. Alguns estudos demonstram uma relação importante entre a pancitopenia e o fator de crescimento insulin-like growth fator-I (IGF-I), no entanto, o seu papel endógeno na hematopoiese ainda não está claro. Propomos estudar a influência desse fator na hematopoiese e sua relação com o desenvolvimento da pancitopenia em hamsteres infectados por via intra-peritoneal com 2x107 de amastigotas por L. (L.) infantum. Avaliamos em 90 e 120 dias pós-infecção a LDU (Leishman-Donovan units) no baço e fígado, quando observamos tendência à progressão da infecção. Aos 60 dias pós-infecção, os animais com LV desenvolveram a plaquetopenia como primeira alteração hematológica, e a partir dos 90 dias pós-infecção, a anemia, e a leucopenia com reduções significantes nos leucócitos totais, linfócitos e neutrófilos. Já aos 120 dias de infecção, os leucócitos totais diminuíram significantemente acompanhados por uma redução de linfócitos, monócitos e eosinófilos. A partir desses dados, focamos a análise da medula óssea nos hamsteres com 90 e 120 pós-infecção. No mielograma, vimos alterações somente nos hamsteres com LV aos 90 dias pós-infecção, com um aumento significante na proporção células mielóides imaturas: células mielóides maduras. Na biópsia da tíbia, houve um aumento significante da celularidade quando comparados com seu respectivo controle, apenas no período de 90 dias pós-infecção. Em adição, observamos uma proliferação e/ou infiltrado macrofágico significante nos hamsteres com LV, mas sem diferença estatística nos períodos de 90 e 120 dias pós-infecção. Na avaliação semi-quantitativa de fibras de reticulina, somente aos 90 dias pós-infecção, observamos aumento significante nos infectados comparados aos controles, caracterizando um quadro fibrótico. Foi medida a expressão de mRNA de IGF-I por PCR em tempo real, aos 90 e 120 dias pós-infecção, onde ocorreu um aumento significante da expressão de IGF-I nos animais infectados em relação aos controles aos 90 dias. Como expostos, os hamsteres com LV apresentam alterações hematológicas como anemia, leucopenia e plaquetopenia, e ainda alterações na medula óssea como aumento da celularidade, proliferação macrofágica e fibrose acompanhados por um aumento da expressão de IGF-I. Assim podemos concluir que nossos dados indicam que o hamster se constitui num bom modelo para o estudo da patogênese da pancitopenia e das alterações medulares decorrentes da infecção por L.(L.) infantum. Neste modelo, ocorre alteração da expressão de IGF-I durante a evolução da infecção com possível papel na patogenia da pancitopenia. / Visceral leishmaniasis is a serious infection that leads to pancytopenia. When it comes to spinal cord dysfunction resulting from infection Leishmania (Leishmania) infantum there are few approaches describing the changes in myelopoiesis and mechanisms that lead to pancytopenia in LV. Some studies have shown a significant relationship between pancytopenia and insulin-like growth factor-growth factor I (IGF-I), however, their endogenous role in hematopoiesis is still not clear. We propose to study the influence of this factor in hematopoiesis and its relationship to the development of pancytopenia in hamsters infected intraperitoneally with 2x107 amastigotes by L. (L.) infantum. Evaluated at 90 and 120 days post-infection the LDU (Leishman-Donovan units) in the spleen and liver, when we observed a tendency to progression of the infection. At 60 days post-infection, animals with LV developed thrombocytopenia as the first hematologic changes, and from 90 days post-infection, anemia, and leukopenia with significant reductions in total leukocytes, lymphocytes and neutrophils. Already at 120 days of infection, total leukocytes decreased significantly accompanied by a decrease lymphocytes, monocytes and eosinophils. From these data, we focus on the analysis of the bone marrow in hamsters with 90 and 120 post-infection. The myelogram changes seen only in hamsters with LV at 90 days post-infection, with a significant increase in the proportion immature myeloid cells: mature myeloid cells. Biopsy of the tibia, there was a significant increase in cellularity compared with their respective control, only 90 days post-infection. In addition, we observed a proliferation and / or infiltration significant macrophage in hamsters with LV, but no statistical difference in the periods of 90 and 120 days post-infection. In semi-quantitative assessment of reticulin fibers, only at 90 days post-infection, we observed a significant increase in infected compared to controls, featuring a fibrous framework. MRNA expression of IGF-I was measured by real-time PCR, at 90 and 120 days post-infection, where a significant increase in IGF-I expression in infected animals compared to controls at 90 days occurred. As set out, the present hamsters VL hematological disorders such as anemia, leukopenia and thrombocytopenia, as well as changes in bone marrow cellularity increased, macrophage proliferation and fibrosis accompanied by a reduction in IGF-I expression. Thus we can conclude that our data indicate that the hamster is a good model to study the pathogenesis of pancytopenia and marrow changes resulting from infection by L. (L.) Infantum. In this model, alteration of IGF-I expression during the course of infection with a possible role in the pathogenesis of pancytopenia.

Aging can be defined as the accumulation of changes affecting the maintenance of homeostatic processes over time, leading to functional decline and increased risk for disease and death. In its simplicity, aging is the systemwide deterioration of an organism. Genetic studies have identified many potential molecular mechanisms of aging including DNA damage, telomere shortening, mitochondrial dysfunction, increased oxidative stress, uncontrolled inflammation, and hormone dysregulation (reviewed in [1]). However, in reality, aging is likely to be a combination of some (or potentially all) of these mechanisms. Interestingly, aging and metabolism are tightly coordinated. Aging is a major contributor to metabolic decline and related diseases, including type 2 diabetes, metabolic syndrome, and cancer. One of the best characterized metabolic pathways implicated in aging is the insulin/IGF-1 signaling (IIS) pathway. Downstream signaling components of the IIS pathway receptor have been well studied and include an interconnected network of signaling events that regulate many physiological outputs. However, less is known about the role of upstream signaling components and how intracellular pathways and physiology are regulated accordingly. In Part I, I present my work towards understanding upstream IIS pathway components using a systems biology approach. The goal of this study is to gain insight into the redundancy and specificity of the insulin gene family responsible for initiating IIS pathway activity in Caenorhabditis elegans. The information gained will serve as a foundation for future studies dissecting the molecular mechanisms of this pathway in efforts to uncouple the downstream signaling and physiological outputs. The clear impact of metabolism on aging and disease stimulated questions regarding the potential of promoting health and longevity through diet and dietary mimetics. Recent findings indicate reduced food intake, meal timing and nutritional modulation of the gut microbiome can ameliorate signs of aging and age-associated diseases. Aging, therefore, is also the result of dynamic and complex interplay between genes of an organism and its environment. In Part II, I will discuss my efforts to gain insight into how diet influences aging. This preliminary study has demonstrated that diet can affect lifespan in the model organism, C. elegans. Additionally, we observe diet-specific effects on drug efficacy that, in turn, modulates C. elegans lifespan and reproduction. The implications of these experiments, while limited, illustrate a potentially greater role in diet- and drug-mediated effects on lifespan.

No description available.

Articular cartilage functions to reduce the mechanical stresses associated with diarthrodial joint movement, protecting these joints over a lifetime of use. Tissue function is maintained through the balance between synthesis and resorption (i.e., metabolism) of extracellular matrix (ECM) by articular chondrocytes (ACs). Two important hormonal regulators of cartilage metabolism are interleukin-1 (IL-1) and insulin-like growth factor-I (IGF-I). These factors have antagonistic effects on chondrocyte activity, and during the progression of osteoarthritis, IL-1 is thought to promote chondrocyte hyporesponsiveness to IGF-I. To better understand how the anabolic (IGF-I) and catabolic (IL-1) stimuli are linked within articular cartilage, we examined the mechanisms by which IL-1 regulates the IGF-I signaling system of ACs. Equine chondrocytes from non-arthritic stifle joints were multiplied over serial passages, re-differentiated in alginate beads, and stimulated with recombinant equine IL-1β. Chondrocytes were assayed for type I IGF receptor (IGF-IR), IGF binding proteins (IGFBPs), and endogenously-secreted IGF-I. Our experimental findings solidify the significance of IL-1 as a key regulator of IGF-I signaling within articular cartilage, demonstrating that regulation of the IGF-I system occurs through both direct (transcription) and indirect (proteolysis) mechanisms. These results have implications for molecular therapies (e.g., gene transfer) directed at reversing osteoarthritic cartilage deterioration. The presented research concerns not only cartilage biology but also tissue engineering strategies for cartilage repair. Alginate hydrogel culture has been reported to re-establish chondrocytic phenotype following monolayer expansion, but studies have not addressed effects on the signaling systems responsible for chondrocyte metabolism. We investigated whether chondrocyte culture history influences the IGF-I system and its regulation by IL-1. ACs expanded by serial passaging were either encapsulated in alginate beads or maintained on tissue culture plastic (TCP). Bead and TCP cells were plated at high-density, stimulated with IL-1β, and assayed for expression of IGF-I signaling mediators. Intermediate alginate culture yielded disparate basal levels of IGF-IR and IGFBP-2, which were attributed to differential transcription. The distinct mediator profiles coincided with varied effects of exogenous IL-1β and IGF-I on collagen Ia1 expression and cell growth rate. This study demonstrates that culture strategy impacts the IGF-I system of ACs, likely impacting their capability to mediate cartilage repair. / Ph. D.

The overall objective of this research was to understand the mechanims by which growth hormone (GH) regulates insulin-like growth factor-I (IGF-I) gene expression in liver. Previous studies have suggested that GH regulation of IGF-I gene expression in liver is mediated by binding of the transcription factor signal transducer and activator of transcription (STAT) 5 to four binding sites located distantly from the IGF-I promoter. The first specific objective of this research was to determine whether additional STAT5 binding sites were involved in GH stimulation of IGF-I gene expression in liver. Sequence analysis of 170 kb of mouse genomic DNA revealed nineteen consensus STAT5 binding sequences corresponding to fourteen ~200 bp chromosomal regions that were conserved in the corresponding human DNA sequence. Eight of these chromosomal regions were able to mediate STAT5 activation of reporter gene expression in cotransfection experiments. Two of these chromosomal regions corresponded to those previously identified. Gel-shift assays indicated that the eight new STAT5 binding sites and three of the four previously identified STAT5 binding sites could bind GH-activated STAT5 from mouse liver. Together, these results suggest that GH stimulation of IGF-I gene transcription in the mouse liver may be mediated by at least eleven STAT5 binding sites located distantly from the IGF-I promoter. In a previous study, I found that liver expression of liver-enriched transcription factor hepatocyte nuclear factor 3γ (HNF-3γ) was increased by GH in cattle. Therefore, the second specific objective of this research was to determine how GH stimulates HNF-3γ gene expression and whether the increased HNF-3γ mediates GH stimulation of IGF-I gene expression in bovine liver. Sequence analysis of the bovine HNF-3γ promoter revealed the presence of two putative binding sites for STAT5. The proximal putative STAT5 binding site appears to be conserved in other mammals. Chromatin immunoprecipitation (ChIP) assays demonstrated that GH increased the binding of STAT5 to the HNF-3γ promoter in bovine liver and that this binding was associated with increased HNF-3γ expression. Gel-shift assays demonstrated that the proximal STAT5 binding site in the HNF-3γ promoter could bind GH-activated STAT5 from bovine liver. Cotransfection analyses showed that the proximal STAT5 binding site was necessary for the HNF-3γ promoter to be activated by GH. The promoter of the bovine IGF-I gene contains three putative HNF-3 binding sites that seem to be evolutionarily conserved. ChIP assays indicated that GH stimulated the binding of HNF-3γ to the IGF-I promoter in bovine liver. Gel-shift assays showed that one of the putative HNF-3 binding sites could bind HNF-3γ protein from bovine liver. Co-transfection analyses demonstrated that this HNF-3 binding site was necessary for HNF-3γ activation of reporter gene expression from the IGF-I promoter. In summary, the results of this dissertation research suggest that GH-activated STAT5 directly stimulates IGF-I gene transcription in liver by binding to at least eleven distantly located STAT5 binding sites in the IGF-I locus and indirectly stimulates IGF-I gene transcription by enhancing HNF-3γ gene expression in the liver. / Ph. D.