Biomedical subjects

Paolo Turrini

Publications and source records attributed to Paolo Turrini.

5 recordsLinked to original sources

PubMed2005

Human hepatocytes in mice receiving pre-immune injection with human cord blood cells.

It is well established that certain subpopulations of human adult stem cells can generate hepatocyte-like cells when transplanted into adult immunosuppressed mice. In the present study, we wanted to explore whether xeno-transplantation of human cord blood CD34(+) (hCBCD34(+)) cells during pre-immune stages of development in immunocompetent mice might also lead to human-mouse liver chimerism. Freshly isolated hCBCD34(+) cells were xeno-transplanted into non-immunosuppressed mice by both intra-blastocyst and intra-fetal injections. One and four weeks after birth, immunostaining for different human-specific hepatocyte markers: human hepatocyte-specific antigen, human serum albumin, and human alpha-1-antitrypsin indicated the presence of human hepatocyte-like cells in the livers of transplanted animals. Detection of human albumin mRNA further corroborated the development of pre-immune human-mouse chimeras. The current report, besides providing new evidence of the potential of hCBCD34(+) cells to generate human hepatocyte-like cells, suggests novel strategies for generating immunocompetent mice harboring humanized liver.

Animals↗

PubMed2004

p21(Waf1/Cip1/Sdi1) mediates shear stress-dependent antiapoptotic function.

OBJECTIVE: The antiapoptotic effect of p21(Waf1/Cip1/Sdi1) (p21) was examined in human umbilical vein endothelial cells (HUVEC) exposed to laminar shear stress (SS) or to the nitric oxide donor sodium nitroprusside (SNP) and in a mouse model of hindlimb ischemia. METHODS: In vitro: Cells were cultured without serum and in the presence of cobalt chloride to simulate hypoxia for 12 h (T0). Shear stress was applied to endothelial cells for additional 12 h. In vivo: Hindlimb ischemia was realized in mice by femoral artery ligation. SNP was acutely administered by subcutaneous injection or by Alzet osmotic pumps for a longer treatment. RESULTS: At T0, HUVEC were either exposed to SS (15 dyn/cm2/s(-1)), treated with SNP or kept in static condition (ST) for 1-12 h; after additional 12 h in ST, 30-35% of cells still alive at T0 had died. In this condition, both SS and SNP treatments markedly increased p21 levels and reduced apoptosis in HUVEC. Recombinant adenoviruses carrying p21 (AdCMV.p21) or antisense p21 (AdCMV.ASp21) cDNA revealed that AdCMV.p21-infected HUVEC were protected from death while AdCMV.ASp21 reduced SS- and SNP-dependent protection from apoptosis. In mice, apoptosis was detected in endothelial cells of ischemic hindlimbs as early as 8 h after femoral artery ligation. Treatment with SNP enhanced p21 expression and protected ischemic tissue from damage. Remarkably, direct in vivo injection of AdCMV.p21 significantly reduced the number of apoptotic nuclei in the presence of ischemia. CONCLUSIONS: The present study establishes that, under our experimental conditions, (a) p21 plays an important role in SS and nitric oxide antiapoptotic effect in vitro, and (b) p21 gene transfer prevents apoptosis in vitro and in vivo, following acute interruption of blood flow.

Adenoviridae↗

PubMed2003

Vascular endothelial growth factor modulates skeletal myoblast function.

Vascular endothelial growth factor (VEGF) expression is enhanced in ischemic skeletal muscle and is thought to play a key role in the angiogenic response to ischemia. However, it is still unknown whether, in addition to new blood vessel growth, VEGF modulates skeletal muscle cell function. In the present study immunohistochemical analysis showed that, in normoperfused mouse hindlimb, VEGF and its receptors Flk-1 and Flt-1 were expressed mostly in quiescent satellite cells. Unilateral hindlimb ischemia was induced by left femoral artery ligation. At day 3 and day 7 after the induction of ischemia, Flk-1 and Flt-1 were expressed in regenerating muscle fibers and VEGF expression by these fibers was markedly enhanced. Additional in vitro experiments showed that in growing medium both cultured satellite cells and myoblast cell line C2C12 expressed VEGF and its receptors. Under these conditions, Flk-1 receptor exhibited constitutive tyrosine phosphorylation that was increased by VEGF treatment. During myogenic differentiation Flk-1 and Flt-1 were down-regulated. In a modified Boyden Chamber assay, VEGF enhanced C2C12 myoblasts migration approximately fivefold. Moreover, VEGF administration to differentiating C2C12 myoblasts prevented apoptosis, while inhibition of VEGF signaling either with selective VEGF receptor inhibitors (SU1498 and CB676475) or a neutralizing Flk-1 antibody, enhanced cell death approximately 3.5-fold. Finally, adenovirus-mediated VEGF(165) gene transfer inhibited ischemia-induced apoptosis in skeletal muscle. These results support a role for VEGF in myoblast migration and survival, and suggest a novel autocrine role of VEGF in skeletal muscle repair during ischemia.

Animals↗

PubMed2002

Nerve growth factor induces angiogenic activity in a mouse model of hindlimb ischemia.

Recent studies suggest that nerve growth factor (NGF), a neurotrophic factor known to play a crucial role in neurite growth and differentiation, may also modulate vascular cell functions. In the present study, it was investigated whether NGF exhibits an angiogenic effect in a mouse model of hindlimb ischemia induced by femoral artery occlusion. Enzyme-linked immunosorbent assay determination revealed an enhanced endogenous NGF production (378 +/- 100 and 54 +/- 26 pg/g tissue in 7 day ischemic and normoperfused adductor muscles, respectively; P<0.05). Furthermore, exogenous NGF, administered subcutaneously for 7 days in ischemic hindlimb, induced a marked increase of arteriole length density (NGF =41 +/- 5 vs. Saline=22 +/- 4 mm/mm(3); P<0.05). However, capillaries were not significantly increased (NGF =1035 +/- 182 vs. Saline= 829 +/- 60 mm/mm(3); P>0.05). In conclusion, the present study provides first evidence that NGF exerts angiogenic properties in vivo.

Animals↗

PubMed1998

A role of the thymus and thymosin-alpha1 in brain NGF levels and NGF receptor expression.

Using neonatal rats we investigated the role of the thymus and thymosin-alpha1 (T-alpha1) in brain NGF levels, NGF receptor (p75NGFr) expression, as well as the activity of choline acetyl-transferase, a cholinergic enzyme regulated by NGF. It is shown that early postnatal thymectomy causes a decrease in NGF in the hippocampus and cortex and p75NGFr distribution in the basal forebrain cholinergic neurons (FBCN). Intracerebral T-alpha1 injection in thymectomized animals induces a recovery, albeit not complete, of both NGF and p75NGFr. These findings indicate that thymectomy affects both the brain NGF producing and responding cells and that T-alpha1 may be one of the thymic hormones involved in the regulation of cerebral NGF synthesis.

Adjuvants, Immunologic↗