9 research outputs found
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
Multipotent adult progenitor cells sustain function of ischemic limbs in mice
Despite progress in cardiovascular research, a cure for peripheral vascular disease has not been found. We compared
the vascularization and tissue regeneration potential of murine and human undifferentiated multipotent
adult progenitor cells (mMAPC-U and hMAPC-U), murine MAPC-derived vascular progenitors (mMAPC-VP),
and unselected murine BM cells (mBMCs) in mice with moderate limb ischemia, reminiscent of intermittent
claudication in human patients. mMAPC-U durably restored blood flow and muscle function and stimulated
muscle regeneration, by direct and trophic contribution to vascular and skeletal muscle growth. This was in
contrast to mBMCs and mMAPC-VP, which did not affect muscle regeneration and provided only limited and
transient improvement. Moreover, mBMCs participated in a sustained inflammatory response in the lower
limb, associated with progressive deterioration in muscle function. Importantly, mMAPC-U and hMAPC-U also
remedied vascular and muscular deficiency in severe limb ischemia, representative of critical limb ischemia in
humans. Thus, unlike BMCs or vascular-committed progenitors, undifferentiated multipotent adult progenitor
cells offer the potential to durably repair ischemic damage in peripheral vascular disease patients
13N-Ammonia PET as a Measurement of Hindlimb Perfusion in a Mouse Model of Peripheral Artery Occlusive Disease
Peripheral arterial occlusive disease (PAOD) is a leading cause of mortality and morbidity in the western world. The development of noninvasive methods for assessment and comparison of the efficacy of novel therapies in animal models is of great importance. Methods: Hindlimb ischemia was induced in nude mice by ligation and excision of the left femoral artery (n = 5) or the left iliac artery (n = 10). Assessment of limb perfusion was performed by small-animal PET analysis after intravenous injection of 13N-ammonia between 24 h and 30 d after surgery using the ratio of perfusion between the left limb (ischemic) and the right limb (control). Activity concentration per area unit was calculated in regions of interest placed on 1-mm-thick images for numeric calculations, and the iliac and the femoral models were compared. In addition, histopathologic studies were performed to assess the degree of necrosis (hematoxylin–eosin) and fibrosis (sirius red). Immunohistochemistry analyses for identification of arterioles ({alpha}-smooth muscle actin) and endothelium—capillaries—(Bandeiraea simplicifolia I [BS-I] lectin) were also performed. Results: Perfusion in both hindlimbs of control animals was similar (median of the left-to-right ratio = 0.99). Twenty-four hours after ischemia, perfusion of the ischemic limb (% mean ± SD) was 33.3 ± 10.6 and 22.1 ± 9.9 in the femoral and iliac models, respectively. Spontaneous recovery of perfusion in the hindlimb that underwent surgery was significantly lower in the iliac model at day +15 (73.2 ± 15.5 vs. 51.9 ± 11.3; P < 0.01). Fibrosis increased progressively until day +30, whereas muscle necrosis was maximal at day +7 with a moderate reduction by day +30. In accordance with this positive effect, there was a statistically significant increase in the area covered with smooth muscle-coated vessels (arterioles) at day +30 in comparison with day 7 (P < 0.05). In addition, a correlation between 13N-ammonia uptake and the amount of necrosis (r = –0.73; P = 0.06) and fibrosis (r = –0.67; P = 0.05) at day +30 was found. Conclusion: 13N-Ammonia imaging allows semiquantitative evaluation of hindlimb perfusion in surgical mouse models of acute hindlimb ischemia. Although spontaneous perfusion recovery is observed in both models, the iliac model shows a substantially lower recovery and is hence better suited for assessment of new therapeutic strategies for acute hindlim
In vitro and in vivo arterial differentiation of human multipotent adult progenitor cells
Many stem cell types have been shown to differentiate into endothelial cells (ECs); however, their specification to arterial or venous endothelium remains unexplored. We tested whether a specific arterial or venous EC fate could be induced in human multipotent adult progenitor cells (hMAPCs) and AC133(+) cells (hAC133(+)). In vitro, in the presence of VEGF(165), hAC133(+) cells only adopted a venous and microvascular EC phenotype, while hMAPCs differentiated into both arterial and venous ECs, possibly because hMAPCs expressed significantly more sonic hedgehog (Shh) and its receptors as well as Notch 1 and 3 receptors and some of their ligands. Accordingly, blocking either of those pathways attenuated in vitro arterial EC differentiation from hMAPCs. Complementarily, stimulating these pathways by addition of Delta-like 4 (Dll-4), a Notch ligand, and Shh to VEGF(165) further boosted arterial differentiation in hMAPCs both in vitro and in an in vivo Matrigel model. These results represent the first demonstration of adult stem cells with the potential to be differentiated into different types of ECs in vitro and in vivo and provide a useful human model to study arteriovenous specification.status: publishe
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
In vitro and in vivo arterial differentiation of human multipotent adult progenitor cells
Many stem cell types have been shown to
differentiate into endothelial cells (ECs);
however, their specification to arterial or
venous endothelium remains unexplored.
We tested whether a specific arterial or
venous EC fate could be induced in human
multipotent adult progenitor cells
(hMAPCs) and AC133 cells (hAC133 ).
In vitro, in the presence of VEGF165,
hAC133 cells only adopted a venous and
microvascular EC phenotype, while
hMAPCs differentiated into both arterial
and venous ECs, possibly because
hMAPCs expressed significantly more
sonic hedgehog (Shh) and its receptors
as well as Notch 1 and 3 receptors and
some of their ligands. Accordingly, blocking
either of those pathways attenuated
in vitro arterial EC differentiation from
hMAPCs. Complementarily, stimulating
these pathways by addition of Delta-like 4
(Dll-4), a Notch ligand, and Shh to VEGF165
further boosted arterial differentiation in
hMAPCs both in vitro and in an in vivo
Matrigel model. These results represent
the first demonstration of adult stem cells
with the potential to be differentiated into
different types of ECs in vitro and in vivo
and provide a useful human model to
study arteriovenous specification
Multipotent adult progenitor cells sustain function of ischemic limbs in mice
Despite progress in cardiovascular research, a cure for peripheral vascular disease has not been found. We compared
the vascularization and tissue regeneration potential of murine and human undifferentiated multipotent
adult progenitor cells (mMAPC-U and hMAPC-U), murine MAPC-derived vascular progenitors (mMAPC-VP),
and unselected murine BM cells (mBMCs) in mice with moderate limb ischemia, reminiscent of intermittent
claudication in human patients. mMAPC-U durably restored blood flow and muscle function and stimulated
muscle regeneration, by direct and trophic contribution to vascular and skeletal muscle growth. This was in
contrast to mBMCs and mMAPC-VP, which did not affect muscle regeneration and provided only limited and
transient improvement. Moreover, mBMCs participated in a sustained inflammatory response in the lower
limb, associated with progressive deterioration in muscle function. Importantly, mMAPC-U and hMAPC-U also
remedied vascular and muscular deficiency in severe limb ischemia, representative of critical limb ischemia in
humans. Thus, unlike BMCs or vascular-committed progenitors, undifferentiated multipotent adult progenitor
cells offer the potential to durably repair ischemic damage in peripheral vascular disease patients