Concise review: programming human pluripotent stem cells into blood

Blood disorders are treated with cell therapies including haematopoietic stem cell (HSC) transplantation as well as platelet and red blood cell transfusions. However the source of cells is entirely dependent on donors, procedures are susceptible to transfusion-transmitted infections and serious complications can arise in recipients due to immunological incompatibility. These problems could be alleviated if it was possible to produce haematopoietic cells in vitro from an autologous and renewable cell source. The production of haematopoietic cells in the laboratory from human induced pluripotent stem cells (iPSCs) may provide a route to realize this goal but it has proven challenging to generate long-term reconstituting HSCs. To date, the optimization of differentiation protocols has mostly relied on the manipulation of extrinsic signals to mimic the in vivo environment. We review studies that have taken an alternative approach to modulate intrinsic signals by enforced expression of transcription factors. Single and combinations of multiple transcription factors have been used in a variety of contexts to enhance the production of haematopoietic cells from human pluripotent stem cells. This programming approach, together with the recent advances in the production and use of synthetic transcription factors, holds great promise for the production of fully functional HSCs in the future.

Exogenous Expression of Human Protamine 1 (hPrm1) Remodels Fibroblast Nuclei into Spermatid-like Structures

Protamines confer a compact structure to the genome of male gametes. Here, we find that somatic cells can be remodeled by transient expression of protamine 1 (Prm1). Ectopically expressed Prm1 forms scattered foci in the nuclei of fibroblasts, which coalescence into spermatid-like structures, concomitant with a loss of histones and a reprogramming barrier, H3 lysine 9 methylation. Protaminized nuclei injected into enucleated oocytes efficiently underwent protamine to maternal histone TH2B exchange and developed into normal blastocyst stage embryos in vitro. Altogether, our findings present a model to study male-specific chromatin remodeling, which can be exploited for the improvement of somatic cell nuclear transfer.

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In vitro protaminization of somatic cell nuclei

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Conversion of interphase somatic nuclei into “spermatid-like” structures

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Protaminization of somatic nuclei that is reversed upon injection into enucleated oocytes

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A simplified model of nuclear remodeling and reprogramming in vitro

Autophagy and apoptosis: parent-of-origin genome-dependent mechanisms of cellular self-destruction

Functional genomic imprinting is necessary for the transfer of maternal resources to mammalian embryos. Imprint-free embryos are unable to establish a viable placental vascular network necessary for the transfer of resources such as nutrients and oxygen. How the parental origin of inherited genes influences cellular response to resource limitation is currently not well understood. Because such limitations are initially realized by the placenta, we studied how maternal and paternal genomes influence the cellular self-destruction responses of this organ specifically. Here, we show that cellular autophagy is prevalent in androgenetic (i.e. having only a paternal genome) placentae, while apoptosis is prevalent in parthenogenetic (i.e. having only a maternal genome) placentae. Our findings indicate that the parental origin of inherited genes determines the placenta's cellular death pathway: autophagy for androgenotes and apoptosis for parthenogenotes. The difference in time of arrest between androgenotes and parthenogenotes can be attributed, at least in part, to their placentae's selective use of these two cell death pathways. We anticipate our findings to be a starting point for general studies on the parent-of-origin regulation of autophagy. Furthermore, our work opens the door to new studies on the involvement of autophagy in pathologies of pregnancy in which the restricted transfer of maternal resources is diagnosed.

Differentiation potential and GFP labeling of sheep bone marrow-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are an important cell population in the bone marrow microenvironment. MSCs have the capacity to differentiate in vitro into several mesenchymal tissues including bone, cartilage, fat, tendon, muscle, and marrow stroma. This study was designed to isolate, expand, and characterize the differentiation ability of sheep bone marrow-derived MSCs and to demonstrate the possibility to permanently express a reporter gene. Bone marrow was collected from the iliac crest and mononuclear cells were separated by density gradient centrifugation. Sheep MSCs cell lines were stable characterized as CD44+ and CD34- and then transfected with a green fluorescent protein (GFP) reporter gene. The GFP expression was maintained in about half (46.6%) of cloned blastocysts produced by nuclear transfer of GFP+ sheep MSCs, suggesting the possibility to establish multipotent embryonic cells' lines carrying the fluorescent tag for comparative studies on the differentiation capacity of adult stem cells (MSCs) versus embryonic stem cells. We found that sheep MSCs under appropriate culture conditions could be induced to differentiate into adipocytes, chondrocytes, and osteoblast lineages. Our results confirm the plasticity of sheep MSCs and establish the foundation for the development of a pre-clinical sheep model to test the efficiency and safety of cell replacement therapy.

A short exposure to polychlorinated biphenyls deregulates cellular autophagy in mammalian blastocyst in vitro

BACKGROUND

Polychlorinated biphenyls (PCBs) are common environmental contaminants that represent an important risk factor of reproductive disorders in chronically exposed human populations. However, it is not known whether a short accidental exposure of embryos to PCBs before implantation might influence their further development and whether the effect might be reversible.

METHODS AND RESULTS

To this aim, in vitro-matured sheep blastocysts were incubated with 2 or 4 µg/ml Aroclor 1254 (A1254), a mixture of 60 PCB congeners for 48 h after which blastocyst proliferation and ability for outgrowth in vitro were assessed. Blastocysts exposed to A1254 showed: (i) reduced proliferation and cell number (particularly in the inner cell mass compartment); (ii) accumulation of vacuoles and lipid droplets, diffused mitochondrial damage and up-regulation of autophagy markers (ATG6 and LC3), all signs indicative of deregulated autophagy, and (iii) massive cell death. Although exposed embryos resumed growth following A1254 removal, their subsequent development remained severely perturbed.

CONCLUSIONS

These findings indicate that short exposure of blastocysts to PCBs leads to its damage characterized by deregulated autophagy and subsequent cell death.

[Serum values of vitamins A, E, C and carotenoids in healthy adult subjects and those with breast neoplasia]

Serum values of retinol, carotenoids, tocopherol and ascorbic acid were assayed in healthy adult females (Group A: 20 cases) and in subjects with fibrocistic mastopathy (Group B: 20 cases), benign breast neoplasms, as fibroadenomas and intraductal papillomas (Group C: 18 cases), and breast carcinoma in situ (Group D: 36 cases). Retinol and carotenoids were evaluated by spectrophotometry using trifluoroacetic acid. Tocopherol was determined by a colorimetric method involving the reduction of Fe to Fe++ by tocopherol with the formation of a red complex of the Fe++ with alpha, alpha'-dipirydyl. Ascorbic acid was estimated by a colorimetric method after derivatization with 2,4-dinitrophenylhydrazine. Our results point out that there is a highly significant decrease (p less than 0.001) of average retinol serum levels in all three patient groups as compared with group A, whereas carotenoids resulted decreased but not significantly. Tocopherol was found to be significantly lower only in groups B (p less than 0.05) and D (p less than 0.01), ascorbic acid in groups B (p less than 0.01) C (p less than 0.05) and D (p less than 0.001).

Vitamins and lipid metabolism

Vitamins play an essential role in lipid metabolism reactions and their presence is therefore absolutely necessary for these reaction to occur. The effect of pantothenic acid, niacin and riboflavin is here described. By transformation into coenzymes these vitamins are involved in fatty acid synthesis and oxidation reactions. Other vitamins, like vitamin B12, folic acid, vitamin C, and essential fatty acids influence lipid metabolism by different mechanisms. Coenzyme B12 and folate coenzyme provide to balance, by methionine synthesis, the pool of methyl radicals necessary for phospholipid biosynthesis. By its involvement in the microsomal respiratory chain, vitamin C promotes cholesterol transformation into bile acids. The essential fatty acids, mainly linoleic acid, are directly connected with cholesterol transport and plasma cholesterol decrease. It is suggested that many lipid metabolism disorders may be due to primary and secondary hypovitaminosis. Nicotinic acid and its derivatives have a particular pharmacological effect since they cause a HDL increase with LDL decrease and improve cholesterol transfer from LDL to HDL. Results of several experiments on the influence of pantothenic acid on polyunsaturated fatty acid metabolism are eventually reported, and these data are related to the effect of the administration of vitamin C at high doses on total cholesterol, triglyceride, lipoprotein, vitamin C and fatty acids of the different plasma lipid fractions.

[Correlations between plasmatic alpha-tocopherol and lipids in male adults]

Plasma levels of alpha-tocopherol, beta-carotene, total lipid, total cholesterol, beta-lipoproteins, and triglyceride were measured in healthy italian male adults of various age groups. Alpha-tocopherol mean values varied from 0.96 mg/100 ml in the subjects of 18-24 years to 1,14 mg/100 ml in the subjects of 25-64 years and to 1,08 mg/100 ml in those above 55 years. No value lower than the generally accepted minimum of 0,5 mg/100 ml was found. Correlation coefficients of all the variables were also studied. Alpha-tocopherol was shown to be significantly related to age and plasma cholesterol. These data agree with other authors' results.

[Vitamin C in the plasma and leukocytes of Italians in different periods of the year]

After briefly mentioning the factors which influence the vitamin C levels in tissues, the findings are reported of an investigation, conducted on 11 volunteers, in which some variations were revealed in vitamin C concentrations in the plasma and in the leukocytes of the subjects examined during a period of one year. The lowest levels were found in the months of March and December.