One-step in vitro generation of ETV2-null pig embryos

Each year, tens of thousands of people worldwide die of end-stage organ failure due to the limited availability of organs for use in transplantation. To meet this clinical demand, one of the last frontiers of regenerative medicine is the generation of humanized organs in pigs from pluripotent stem cells (PSCs) via blastocyst complementation. For this, organ-disabled pig models are needed. As endothelial cells (ECs) play a critical role in xenotransplantation rejection in every organ, we aimed to produce hematoendothelial-disabled pig embryos targeting the master transcription factor ETV2 via CRISPR-Cas9-mediated genome modification. In this study, we designed five different guide RNAs (gRNAs) against the DNA-binding domain of the porcine ETV2 gene, which were tested on porcine fibroblasts in vitro. Four out of five guides showed cleavage capacity and, subsequently, these four guides were microinjected individually as ribonucleoprotein complexes (RNPs) into one-cell-stage porcine embryos. Next, we combined the two gRNAs that showed the highest targeting efficiency and microinjected them at higher concentrations. Under these conditions, we significantly improved the rate of biallelic mutation. Hence, here, we describe an efficient one-step method for the generation of hematoendothelial-disabled pig embryos via CRISPR-Cas9 microinjection in zygotes. This model could be used in experimentation related to the in vivo generation of humanized organs

Generation of an induced pluripotent stem cell line (ESi107-A) from a transthyretin amyloid cardiomyopathy (ATTR-CM) patient carrying a p.Ser43Asn mutation in the TTR gene

Transthyretin (TTR) amyloid cardiomyopathy (ATTR-CM) is a life-threatening disease caused by the abnormal production of misfolded TTR protein by liver cells, which is then released systemically. Its amyloid deposition in the heart is linked to cardiac toxicity and progression toward heart failure. A human induced pluripotent stem cell (iPSC) line was generated from peripheral blood mononuclear cells (PBMCs) from a patient suffering familial transthyretin amyloid cardiomyopathy carrying a c.128G>A (p.Ser43Asn) mutation in the TTR gene. This iPSC line offers a useful resource to study the disease pathophysiology and a cell-based model for therapeutic discovery

Context-dependent regulation of endothelial cell metabolism: differential effects of the PPARβ/δ agonist GW0742 and VEGF-A

Peroxisome proliferator activated receptor β/δ (PPARβ/δ) has pro-angiogenic functions, but whether PPARβ/δ modulates endothelial cell metabolism to support the dynamic phenotype remains to be established. This study characterised the metabolic response of HUVEC to the PPARβ/δ agonist, GW0742, and compared these effects with those induced by VEGF-A. In HUVEC monolayers, flux analysis revealed that VEGF-A promoted glycolysis at the expense of fatty acid oxidation (FAO), whereas GW0742 reduced both glycolysis and FAO. Only VEGF-A stimulated HUVEC migration and proliferation whereas both GW0742 and VEGF-A promoted tubulogenesis. Studies using inhibitors of PPARβ/δ or sirtuin-1 showed that the tubulogenic effect of GW0742, but not VEGF-A, was PPARβ/δ- and sirtuin-1-dependent. HUVEC were reliant on glycolysis and FAO, and inhibition of either pathway disrupted cell growth and proliferation. VEGF-A was a potent inducer of glycolysis in tubulogenic HUVEC, while FAO was maintained. In contrast, GW0742-induced tubulogenesis was associated with enhanced FAO and a modest increase in glycolysis. These novel data reveal a context-dependent regulation of endothelial metabolism by GW0742, where metabolic activity is reduced in monolayers but enhanced during tubulogenesis. These findings expand our understanding of PPARβ/δ in the endothelium and support the targeting of PPARβ/δ in regulating EC behaviour and boosting tissue maintenance and repair

MAPC transplantation confers a more durable benefit than AC133+ cell transplantation

There is a need for comparative studies to determine which cell types are better candidates to remedy ischemia. Here, we compared human AC133+ cells and Multipotent Adult Progenitor Cells (hMAPC) in a mouse model reminiscent of critical limb ischemia. hMAPC or hAC133+ cell transplantation induced a significant improvement in tissue perfusion (measured by microPET) 15 days post-transplantation compared to controls. This improvement persisted for 30 days in hMAPC-treated but not in hAC133+-injected animals. While transplantation of hAC133+ cells promoted capillary growth, hMAPC transplantation also induced collateral expansion, decreased muscle necrosis/fibrosis and improved muscle regeneration. Incorporation of differentiated hAC133+ or hMAPC progeny into new vessels was limited, however, a paracrine angio/arteriogenic effect was demonstrated in animals treated with hMAPC. Accordingly, hMAPC-, but not hAC133+-conditioned media, stimulated vascular cell proliferation and prevented myoblast, endothelial and smooth muscle cell apoptosis in vitro. Our study suggests that although hAC133+ cell and hMAPC transplantation bothcontribute to vascular regeneration in ischemic limbs, hMAPC exert a more robust effect through trophic mechanisms, which translated into collateral and muscle fiber regeneration. This, in turn, conferred tissue protection and regeneration with longer-term functional improvement

Cellule staminali

Le cellule staminali sono cellule non specializzate presenti in tutti gli organismi viventi. Diversamente da una cellula epiteliale, capace di produrre una barriera biologica a difesa del nostro organismo, o da un globulo rosso, in grado di trasportare l\u2019ossigeno attraverso il circolo sanguigno, una cellula staminale non possiede alcuna specializzazione fisiologica. La definizione di cellula staminale si basa essenzialmente su due caratteristiche: a) autorinnovamento, ossia la capacit\ue0 di generare una cellula indifferenziata esattamente uguale alla cellula-madre attraverso numerosi cicli cellulari; b) potenza, vale a dire la capacit\ue0 di differenziarsi in tipi cellulari specializzati. Si distinguono diversi stadi di potenza delle cellule staminali: la totipotenza \ue8 la capacit\ue0 di generare tutti i tessuti embrionali ed extraembrionali, tipica delle cellule della morula; la pluripotenza \ue8 la capacit\ue0 di differenziarsi in tutti i tessuti embrionali, tipica delle cellule staminali embrionali (ES, Embryonic Stem cells) che compongono la massa cellulare interna della blastocisti, capacit\ue0 che recentemente \ue8 stata riferita anche a cellule somatiche riprogrammate; la multipotenza \ue8 la capacit\ue0 di differenziare in tutti i tipi cellulari di un foglietto germinativo (endoderma, mesoderma o ectoderma); l\u2019unipotenza \ue8 la capacit\ue0 di differenziarsi in un unico tipo cellulare, tipico dei progenitori. In questo saggio verranno descritte le cellule staminali embrionali e adulte fino alle innovative cellule staminali pluripotenti indotte (iPS, induced Pluripotent Stem cells), la sfida scientifica del nuovo secolo

MAPC transplantation confers a more durable benefit than AC133+ cell transplantation

There is a need for comparative studies to determine which cell types are better candidates to remedy ischemia. Here, we compared human AC133+ cells and Multipotent Adult Progenitor Cells (hMAPC) in a mouse model reminiscent of critical limb ischemia. hMAPC or hAC133+ cell transplantation induced a significant improvement in tissue perfusion (measured by microPET) 15 days post-transplantation compared to controls. This improvement persisted for 30 days in hMAPC-treated but not in hAC133+-injected animals. While transplantation of hAC133+ cells promoted capillary growth, hMAPC transplantation also induced collateral expansion, decreased muscle necrosis/fibrosis and improved muscle regeneration. Incorporation of differentiated hAC133+ or hMAPC progeny into new vessels was limited, however, a paracrine angio/arteriogenic effect was demonstrated in animals treated with hMAPC. Accordingly, hMAPC-, but not hAC133+-conditioned media, stimulated vascular cell proliferation and prevented myoblast, endothelial and smooth muscle cell apoptosis in vitro. Our study suggests that although hAC133+ cell and hMAPC transplantation bothcontribute to vascular regeneration in ischemic limbs, hMAPC exert a more robust effect through trophic mechanisms, which translated into collateral and muscle fiber regeneration. This, in turn, conferred tissue protection and regeneration with longer-term functional improvement

Increased cardiac myocyte PDE5 levels in human and murine pressure overload hypertrophy cntribute to adverse LV remodeling

Background: The intracellular second messenger cGMP protects the heart under pathological conditions. We examined expression of phosphodiesterase 5 (PDE5), an enzyme that hydrolyzes cGMP, in human and mouse hearts subjected to sustained left ventricular (LV) pressure overload. We also determined the role of cardiac myocyte-specific PDE5 expression in adverse LV remodeling in mice after transverse aortic constriction (TAC). Methodology/Principal Findings: In patients with severe aortic stenosis (AS) undergoing valve replacement, we detected greater myocardial PDE5 expression than in control hearts. We observed robust expression in scattered cardiac myocytes of those AS patients with higher LV filling pressures and BNP serum levels. Following TAC, we detected similar, focal PDE5 expression in cardiac myocytes of C57BL/6NTac mice exhibiting the most pronounced LV remodeling. To examine the effect of cell-specific PDE5 expression, we subjected transgenic mice with cardiac myocyte-specific PDE5 overexpression (PDE5TG) to TAC. LV hypertrophy and fibrosis were similar as in WT, but PDE5-TG had increased cardiac dimensions, and decreased dP/dt(max) and dP/dt(min) with prolonged tau (P, 0.05 for all). Greater cardiac dysfunction in PDE5-TG was associated with reduced myocardial cGMP and SERCA2 levels, and higher passive force in cardiac myocytes in vitro. Conclusions/Significance: Myocardial PDE5 expression is increased in the hearts of humans and mice with chronic pressure overload. Increased cardiac myocyte-specific PDE5 expression is a molecular hallmark in hypertrophic hearts with contractile failure, and represents an important therapeutic target

Revealing cell populations catching the early stages of human embryo development in naive pluripotent stem cell cultures

Naive human pluripotent stem cells (hPSCs) are defined as the in vitro counterpart of the human preimplantation embryo's epiblast and are used as a model system to study developmental processes. In this study, we report the discovery and characterization of distinct cell populations coexisting with epiblast-like cells in 5iLAF naive human induced PSC (hiPSC) cultures. It is noteworthy that these populations closely resemble different cell types of the human embryo at early developmental stages. While epiblast-like cells represent the main cell population, interestingly we detect a cell population with gene and transposable element expression profile closely resembling the totipotent eight-cell (8C)-stage human embryo, and three cell populations analogous to trophectoderm cells at different stages of their maturation process: transition, early, and mature stages. Moreover, we reveal the presence of cells resembling primitive endoderm. Thus, 5iLAF naive hiPSC cultures provide an excellent opportunity to model the earliest events of human embryogenesis, from the 8C stage to the peri-implantation period