Monocyte adhesion to balloon-injured arteries: the influence of endothelial cell seeding

Oligonucleotide Microarrays Identified Potential Regulatory Genes Related to Early Outward Arterial Remodeling Induced by Tissue Plasminogen Activator

Constrictive vascular remodeling limiting blood flow, as well as compensatory outward remodeling, has been observed in many cardiovascular diseases; however, the underlying mechanisms regulating the remodeling response of the vessels remain unclear. Plasminogen activators (PA) are involved in many of the processes of vascular remodeling. We have shown previously that increased levels of tissue-type PA (tPA) contributes to outward vascular remodeling. To elucidate the mechanisms involved in the induction of outward remodeling we characterized changes in the expression profiles of 8799 genes in injured rat carotid arteries 1 and 4 days after recombinant tPA treatment compared to vehicle. Periadventitial tPA significantly increased lumen size and vessel area, encompassed by the external elastic lamina, at both one and 4 days after treatment. Among 41 differentially expressed known genes 1 day after tPA application, five genes were involved in gene transcription, five genes were related to the regulation of vascular tone [for example, thromboxane A2 receptor (D32080) or non-selective-type endothelin receptor (S65355)], and eight genes were identified as participating in vascular innervation [for example, calpain (D14478) or neural cell adhesion molecule L1 (X59149)]. Four days after injury in tPA-treated arteries, four genes, regulating vascular tone, were differentially expressed. Thus, tPA promotes outward arterial remodeling after injury, at least in part, by regulating expression of genes in the vessel wall related to function of the nervous system and vascular tone.

Adaptive changes in autogenous vein grafts for arterial reconstruction: clinical implications

For patients with the most severe manifestations of lower extremity arterial occlusive disease, bypass surgery using autogenous vein has been the most durable reconstruction. However, the incidence of bypass graft stenosis and graft failure remains substantial and wholesale improvements in patency are lacking. One potential explanation is that stenosis arises not only from over exuberant intimal hyperplasia, but also due to insufficient adaptation or remodeling of the vein to the arterial environment. Although in vivo human studies are difficult to conduct, recent advances in imaging technology have made possible a more comprehensive structural examination of vein bypass maturation. This review summarizes recent translational efforts to understand the structural and functional properties of human vein grafts and places it within the context of the rich existing literature of vein graft failure.

Mesenchymal stem cells participating in ex vivo endothelium repair and its effect on vascular smooth muscle cells growth

BACKGROUND

Previous studies have shown that mesenchymal stem cells (MSCs) transplantation can promote neovascularization and regenerate damaged myocardium. However, it remains unknown whether MSCs seeding can be used to repair injured cellular components in vascular diseases. In this study we explored the feasibility of applying MSCs to endothelium repair in endothelial damage and vasoproliferative disorders.

METHODS

Ex vivo model of endothelium repair was developed in which rabbit vascular smooth muscle cells (SMCs) were inoculated into the upper chamber and rabbit endothelial cells (ECs)/human MSCs into the lower chamber of a co-culture system. 3H-TdR incorporation and PCNA protein expression were assayed and migrated number of SMCs was calculated to evaluate the effect of MSCs seeding on SMCs growth. Flk-1 and vWF protein expressions were observed to analyze the plasticity of the seeded MSCs along endothelial lineage.

RESULTS

In this co-culture system, no vWF protein but Flk-1 protein was observed in the 25.71% of MSCs after having been co-cultured with mature rabbit ECs for 5 days. Compared with the control group, the proliferation and migration of SMCs was significantly increased by proliferative ECs but decreased by confluent ECs (n=6, P<0.01). MSCs seeding decreased the proliferation and migration of SMCs compatible with the effect of proliferative ECs (n=6, P<0.001). However, no inhibition on SMCs growth was observed with MSCs seeding in comparison to the effect of confluent ECs.

CONCLUSIONS

MSCs seeding can inhibit the proliferation and migration of SMCs. MSCs co-cultured with mature ECs have the ability to undergo milieu-dependent differentiation toward ECs.

Monocyte adhesion to human vein grafts: a marker for occult intraoperative injury?

OBJECTIVE

Monocyte adhesion to the vessel wall is believed to be an important initiating event in atherosclerosis and intimal hyperplasia. We hypothesized that occult intraoperative vein injury induces an immediate increase in monocyte adhesion that may be critical to the development of vein graft disease.

METHODS

Vein segments were obtained from patients (n = 23) undergoing lower extremity bypass. The initial segment (V1, n = 17) was excised immediately at the time of conduit harvest. A second segment (V2, n = 23) was obtained from the distal conduit just before performing the distal anastomosis. Segments were incubated with radiolabeled THP-1 cells (monocytoid cell line) for 1 hour at 37 degrees C, then rinsed and solubilized for determination of bound radioactivity. In a subset of grafts (n = 4), THP-1 cells were preincubated with monoclonal antibody (mAB) 7E3 (which binds to the monocyte integrin Mac-1 at its fibrinogen [Fg]-binding site) or control (mAB 14E11). Fg deposition and endothelial coverage were evaluated by immunohistochemistry (n = 10). Statistical analysis was performed using the paired t test and analysis of variance. Follow-up graft patency data were obtained and correlated with adhesion values using an exact test (StatXact, Cytel Software, Cambridge, Mass).

RESULTS

Monocyte adhesion was significantly increased after surgical manipulation (V1, 2400 +/- 770 versus V2, 7343 +/- 1555 cells/cm(2); P <.02). Fg deposition was abundant in V2 sections and not seen in V1. Monocyte adhesion to V2 segments was significantly reduced (58% of control, P <.01) by 7E3 treatment. Graft follow-up was complete with a mean interval of 11 months. Higher V2 adhesion values were associated with occluded grafts (P =.07). The median value for the six occluded grafts was 6234 cells/cm(2) versus 3892 cells/cm(2) for the 17 patent grafts.

CONCLUSIONS

Monocyte adhesion to the vein wall is immediately increased after surgical manipulation and is inhibited by mAB 7E3. Early monocyte adhesion to vein grafts is likely to involve interactions between Mac-1 and Fg. Heightened levels of monocyte adhesion at implantation may be a marker for subsequent vein graft failure.

Targeting platelet aggregation: CD39 gene transfer augments nucleoside triphosphate diphosphohydrolase activity in injured rabbit arteries

BACKGROUND

CD39, the major endothelial nucleoside triphosphate diphosphohydrolase (NTPDase), plays an important role in local thromboregulation. We hypothesized that balloon injury (BI) leads to an acute reduction in arterial NTPDase activity that could be restored by a targeted gene delivery strategy.

METHODS

Recombinant adenoviral vectors containing human CD39 (Ad-CD39) or beta-galactosidase (Ad-LacZ) were used. Endothelial (ECs) and smooth muscle cells (SMCs) were infected in vitro and NTPDase activity measured. New Zealand white rabbits (N = 28) underwent bilateral iliofemoral artery balloon injury, followed by incubation with Ad-CD39, Ad-LacZ, or vehicle. Explanted vessels were analyzed for NTPDase activity and localization of CD39 expression by immunohistochemistry. Deposition of fluorescent-labeled platelets was studied 3 days after injury and vector treatment.

RESULTS

In vitro, Ad-CD39 infection resulted in a greater than 40-fold increase in adenosine diphosphatase activity in ECs and a 3-fold increase in SMCs. In vivo, CD39 transgene expression localized to the luminal aspect of Ad-CD39--treated vessels. BI resulted in an acute reduction in vessel wall NTPDase activity (P <.05). Ad-CD39 augmented NTPDase activity when compared with vehicle or Ad-LacZ (P <.05). Platelet deposition on the injured arterial surface was modest and not different between Ad-CD39-- and Ad-LacZ--treated vessels.

CONCLUSIONS

BI decreases native NTPDase activity, which can be augmented by adenovirus-mediated gene transfer of CD39. Further studies are required to determine whether targeted delivery of CD39 could convey thromboprotective properties to an injured vessel.