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Various in vitro methods have been used for biological and synthetic scaffold fabrication. Some use polymers such as expanded polytetrafluoroethylene (ePTFE), polytetrafluoroethylene (PTFE), and polyethylene terephthalate (PET), while others use allogeneic or xenogeneic biological materials (e.g. blood vessels). While fabricating a biological scaffold, the first step is complete decellularization by enzymes (e.g. trypsin, collagenase, etc.) or chemicals (e.g. SDS, Triton-X, etc.), and the scaffolds should maintain its extracellular matrix (ECM). The second step involves re-endothelization so as to get fully biomimetic graft. In this study, we focused (concentrated) on the fabrication of a human saphenous vein scaffold by using various chemicals. We observed that cationic 1% SDS solution (Group B) performed excellent decellularization without altering the extracellular matrix as compared to the other chemicals like 0.25% trypsin and 70% ethanol (Groups C and D). Decellularization percentage and intactness of ECM (in all tunicae – intima, media, and adventitia) were confirmed based on histology. The PicoGreen assay showed that Group B (1% SDS decellularized scaffold, n = 3) had no detectable residual DNA. Re-endothelization on the complete decellularized scaffold (Group B) was done in both ways, without initial fibrin glue application (Group E) and with prior fibrin glue application (Group F). The vWF and lectin expressions suggested that endothelial cells did not alter their phenotype on human saphenous vein scaffolds. Uniaxial tensile testing revealed no significant differences in strain characteristics and modulus between native tissue and decellularized scaffolds. The live-dead (FDA/PI) and MTT assays confirmed the endothelial cell proliferation and viability, and the scanning electron microscope (SEM) data showed that the cells adhered to the scaffold matrix (Group F). We concluded that an allogeneic human saphenous vein scaffold with desirable properties can be fabricated and re-endothelialized to form a non-thrombogenic intimal surface in vitro using this protocol.

Staphylococcus aureus causes severe, life-threatening infections that often are complicated by severe local and systemic pathologies with non-healing lesions. A classic example is S. aureus infective endocarditis (IE), where the secreted hemolysin β-toxin potentiates the disease via its sphingomyelinase and biofilm ligase activities. Although these activities dysregulate human aortic endothelial cell activation, β-toxin effect on endothelial cell function in wound healing has not been addressed. With the use of the ex vivo rabbit aortic ring model, we provide evidence that β-toxin prevents branching microvessel formation, highlighting its ability to interfere with tissue re-vascularization and vascular repair. We show that β-toxin specifically targets both human aortic endothelial cell proliferation and cell migration and inhibits human umbilical vein endothelial cell rearrangement into capillary-like networks in vitro. Proteome arrays specific for angiogenesis-related molecules provided evidence that β-toxin promotes an inhibitory profile in endothelial cell monolayers, specifically targeting production of TIMP-1, TIMP-4, and IGFBP-3 to counter the effect of a pro-angiogenic environment. Dysregulation in the production of these molecules is known to result in sprouting defects (including deficient cell proliferation, migration, and survival), vessel instability and/or vascular regression. When endothelial cells are grown under re-endothelialization/wound healing conditions, β-toxin decreases the pro-angiogenic molecule MMP-8 and increases the anti-angiogenic molecule endostatin. Altogether, the data indicate that β-toxin is an anti-angiogenic virulence factor and highlight a mechanism where β-toxin exacerbates S. aureus invasive infections by interfering with tissue re-vascularization and vascular repair.

Background Neointimal hyperplasia induced by interventional surgery can lead to progressive obliteration of the vascular lumen, which has become a major factor affecting prognosis. It is commonly accepted that the rate of re-endothelialization is inversely related to neointima formation. Growth differentiation factor 11 (GDF11) is a secreted protein with anti-inflammatory, antioxidant, and anti-aging properties. Recent reports indicate that GDF11 can improve vascular remodeling by maintaining differentiated phenotypes for vascular smooth muscle cells. However, it is not known whether and how GDF11 acts to promote re-endothelialization in vascular injury. The present study was performed to clarify the influence of GDF11 on re-endothelialization after vascular injury. Methods An adult Sprague-Dawley rat model of common-carotid-artery balloon-dilatation injury was surgically established. A recombinant adenovirus carrying GDF11 was delivered into the common carotid artery to overexpress GDF11. Vascular re-endothelialization and neointima formation were carried out on harvested carotid arteries through histomolecular analysis. CCK8 analysis, LDH release and western blotting were performed to investigate the effects of GDF11 on endothelial NLRP3-inflammasome activation and relevant signaling pathways in vitro. Results GDF11 significantly enhanced re-endothelialization and reduced neointima formation in rats with balloon-dilatation injury by suppressing the activation of the NLRP3 inflammasome. Endoplasmic-reticulum stress (ER stress) inhibitor, 4PBA administration attenuated endothelial NLRP3-inflammasome activation induced by Lysophosphatidylcholine. Besides, up-regulation of LOX1 expression involved elevated endoplasmic-reticulum stress, and could result in endothelial NLRP3-inflammasome activation. Moreover, GDF11 significantly inhibited NLRP3-inflammasome-mediated endothelial cell pyroptosis through the negative regulation of LOX-1-dependent ER stress. Conclusions We conclude that GDF11 improves re-endothelialization and can attenuate vascular remodeling by reducing endothelial NLRP3-inflammasome activation. These findings shed light on new treatment strategies to promote re-endothelialization based on GDF11 as a future target.

The vascular endothelium, which plays an essential role in maintaining the normal shape and function of blood vessels, is a natural barrier between the circulating blood and the vascular wall tissue. The endothelial damage can cause vascular lesions, such as atherosclerosis and restenosis. After the vascular intima injury, the body starts the endothelial repair (re-endothelialization) to inhibit the neointimal hyperplasia. Endothelial progenitor cell is the precursor of endothelial cells and plays an important role in the vascular re-endothelialization. However, re-endothelialization is inevitably affected in vivo and in vitro by factors, which can be divided into two types, namely, promotion and inhibition, and act on different links of the vascular re-endothelialization. This article reviews these factors and related mechanisms.

Decellularized liver scaffolds based liver engineering is a promising approach toward developing functional liver surrogates. However, a major obstacle to long-term transplantation is the hemocompatibility of the bioengineered liver surrogates. One approach to improve the hemocompatibility of engineered liver surrogates is re-endothelialization. In the current study, immortalized endothelial cells were perfused for re-endothelialization of decellularized rat liver scaffolds. When compared to the media-based perfusion approach, gelatin hydrogels-based perfusion significantly increased the number of cells that were retained in the decellularized liver scaffolds and the vascular lumen coverage ratio. Endothelial cells were lining along the vasculatures of the decellularized liver scaffolds and actively proliferating. Re-endothelialization improved the blood retention ability of the liver scaffold vasculatures. Doppler ultrasound detected active blood flows within the re-endothelialized liver scaffold transplants 8 days post-transplantation. Our results strengthened the feasibility of developing bioengineered liver surrogates utilizing decellularized liver scaffolds. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 392-402, 2019.

Tissue engineering utilizes an interdisciplinary approach to generate constructs for the treatment and repair of diseased organs. Generation of small vessels as vascular grafts or as envisioned central vessel for vascularized constructs is still a challenge. Here, the decellularization of porcine vessels by a non-detergent based protocol was developed and investigated. Perfusion-decellularization with sodium hydroxide solution resulted in removal of cellular material throughout the whole length of the vessel while preserving structural and mechanical integrity. A re-endothelialization of the retrieved matrix with human umbilical vein endothelial cells and cardiac endothelial cells was achieved through rotation-based seeding employing a custom-made bioreactor. A confluent monolayer was detected on the entire luminal surface. Thus, a non-detergent-based decellularization method allowing the re-endothelialization of the luminal surface was developed in this study, thereby paving the way for future implementation of the resulting construct as vascular graft or as central vessel for tissue engineered constructs in need of a perfusion system with readily available anastomosis sites.

INTRODUCTION AND OBJECTIVE:Corpora cavernosa vascular endothelium injury is an important cause of erectile dysfunction (ED). Targeted repair of penile vascular endothelium is a vital way for ED tre...

Background The aim of this study was to characterize the mechanical and physio-biological properties of peptide-coated stent (PCS) compared to commercialized drug-eluting stents (DESs). Methods WKYMVm (Trp-Lys-Tyr-Met-Val-D-Met), a stimulating peptide for homing endothelial colony-forming cell was specially synthesized and coated to bare metal stent (BMS) by dopamine-derived coordinated bond. Biological effects of PCS were investigated by endothelial cell proliferation assay and pre-clinical animal study. And mechanical properties were examined by various experiment. Results The peptide was well-coated to BMS and was maintained and delivered to 21 and 7 days in vitro and in vivo, respectively. Moreover, the proliferation of endothelial cell in PCS group was increased (approximately 36.4 ± 5.77%) in PCS group at 7 day of culture compare to BMS. Although, the radial force of PCS was moderated among study group. The flexibility of PCS was (0.49 ± 0.082 N) was greatest among study group. PCS did not show the outstanding performance in recoil and foreshortening test (3.1 ± 0.22% and 2.1 ± 0.06%, respectively), which was the reasonable result under the guide line of FDA (less than 7.0%). The nominal pressure (3.0 mm in a diameter) of PCS established by compliance analysis was 9 atm. The changing of PCS diameter by expansion was similar to other DESs, which is less than 10 atm of pressure for the nominal pressure. Conclusions These results suggest that the PCS is not inferior to commercialized DES. In addition, since the PCS was fabricated as polymer–free process, secondary coating with polymer-based immunosuppressive drugs such as –limus derivatives may possible.

The coronary artery stent has been widely used in clinic. In-stent restenosis was mainly caused by the excessive proliferation of smooth muscle cell and the inflammation due to the metal ion released from stent scaffold of the drug-eluting stent. Thus, to reduce the in-stent restenosis and promote the vascular endothelialization have become a hot research point in this area. In this paper, a nano-TiO2ceramic coating was deposited on 316L stainless steel to reduce the metal ion release and to inhibit the inflammation reaction. An endothelia cell selective adhesion peptide Arg-Glu-Asp-Val (REDV) coating was prepared on the ceramic coating by a polydopamine technology to promote the endothelialization. The corrosion test indicated that nano-TiO2ceramic film could effectively decrease the nickel ion released from 316L stainless steel. REDV/TiO2coating could promote the endothelial cell adhesion and proliferation, meanwhile REDV/TiO2coating could also increase the nitric oxide concentration. Bare metal stent, TiO2-coated stent and REDV/TiO2-coated stent were implanted in the iliac arteries of rabbit model. In-stent restenosis and re-endothelialization were evaluated at 28 days post-implantation of the stents. The results showed that REDV/TiO2-coated stents could effectively reduce in-stent restenosis and promote re-endothelialization in comparison with TiO2-coated drug-eluting stent and bare metal stent. These results suggest that REDV/TiO2-coated drug-eluting stent maybe a good choice of the application for coronary artery disease.

Dysfunction of endothelial progenitor cells (EPCs) give rise to deficient endothelial reparative capacity in patients with hypertension; however the mechanisms remain poorly defined. Mitochondrial superoxide (mtSO) is implicated in the pathogenesis of endothelial injury in hypertension. Acetylation

A wide variety of environmental cues provided by the extracellular matrix, including biophysical and biochemical cues, are responsible for vascular cell behavior and function. In particular, substrate topography and surface chemistry have been shown to regulate blood and vascular compatibility individually. The combined impact of chemical and topographic cues on blood and vascular compatibility, and the interplay between these two types of cues, are subjects that are currently being explored. In the present study, a facile polydopamine-mediated approach is introduced for immobilization of heparin on topographically patterned substrates, and the combined effects of these cues on blood compatibility and re-endothelialization are systematically investigated. The results show that immobilized heparin and substrate topography cooperatively modulate anti-coagulation activity, endothelial cell (EC) attachment, proliferation, focal adhesion formation and endothelial marker expression. Meanwhile, the substrate topography is the primary determinant of cell alignment and elongation, driving in vivo-like endothelial organization. Importantly, combining immobilized heparin with substrate topography empowers substantially greater competitive ability of ECs over smooth muscle cells than each cue individually. Moreover, a model is proposed to elucidate the cooperative interplay between immobilized heparin and substrate topography in regulating cell behavior.

Cardiovascular diseases are considered as one of the serious diseases that leads to the death of millions of people all over the world. Stent implantation has been approved as an easy and promising way to treat cardiovascular diseases. However, in-stent restenosis and thrombosis remain serious problems after stent implantation. It was demonstrated in a large body of previously published literature that endothelium impairment represents a major factor for restenosis. This discovery became the driving force for many studies trying to achieve an optimized methodology for accelerated re-endothelialization to prevent restenosis. Thus, in this review, we summarize the different methodologies opted to achieve re-endothelialization, such as, but not limited to, manipulation of surface chemistry and surface topography.

Background Current commercially available drug-eluting stents (DESs) are criticized for the problem of stent thrombosis by induced impaired re-endothelialization (RE). The solving of this challenge could be boosted by endothelial progenitor cells (EPCs). The purpose of this study was to examine the effects of hepatocyte growth factor (HGF) on this process. Methods The abundance and functional capacity of circulating EPC was analyzed by a fluorescence-activated cell sorter and western blot. The in vivo effect of HGF on DES patency, RE, and neointimal formation was investigated in a hypercholesterolemic rabbit model. Results After 7 days of HGF administration, the number of CD34+/CD133+ progenitor cells had increased significantly. HGF also significantly inhibited the onset of senescence of EPC due to a decrease in protein expression of p53 and p21. In the in vivo study, HGF-treated DES had a higher patency rate than the control group (11/12 vs. 6/12, P = 0.032). Moreover, the HGF-treated group exhibited better RE (control group: 69.5 ± 12.9%, HGF group: 88.8 ± 8.4%, P = 0.006), but significantly smaller areas of neointima (control group: 0.68 ± 0.15 mm 2 , HGF group: 0.45 ± 0.18 mm 2 , P = 0.02). Conclusion HGF efficiently ameliorates the vascular response to stent implantation, and has an important redeeming influence on the deleterious endothelial effects of DES.

Decellularized extracellular matrix has long been applied as a scaffold material in tissue engineering. Recent investigation into decellularized whole solid organs has shown that the remaining extracellular matrix preserves the underlying architecture and protein organization inherent to the tissue. Decellularized whole organ scaffolds are of particular interest to renal regeneration owing to the complex nature of the kidneys because the extracellular matrix contains intact vascular and tubular networks. This chapter summarizes recent developments in whole organ scaffolds for kidney regeneration.

The cellular and molecular processes that control vascular injury responses after percutaneous coronary intervention involve a complex interplay among vascular cells and progenitor cells that control arterial remodeling, neointimal proliferation, and re-endothelialization. Drug-eluting stents (DES) improve the efficacy of percutaneous coronary intervention by modulating vascular inflammation and preventing neointimal proliferation and restenosis. Although positive effects of DES reduce inflammation and restenosis, negative effects delay re-endothelialization and impair endothelial function. Delayed re-endothelialization and impaired endothelial function are linked to stent thrombosis and adverse clinical outcomes after DES use. Compared with bare-metal stents, DES also differentially modulate mobilization, homing, and differentiation of vascular progenitor cells involved in re-endothelialization and neointimal proliferation. The effects of DES on vascular inflammation and repair directly impact clinical outcomes with these devices and dictate requirements for extended-duration dual antiplatelet therapy.

Endothelial injury plays a critical role in the initiation of a variety of proliferative vascular diseases. Several studies indicated that miR-17-5p provides a cell-intrinsic antiangiogenic activity in tumorogenesis. However, the functions of miR-17-5p in endothelium growth and vascular remodeling

It is not clear what effects of CD34- and CD133-specific antibody-coated stents have on re-endothelialization and in-stent restenosis (ISR) at the early phase of vascular injury. This study aims at determining the capabilities of different coatings on stents (e.g. gelatin, anti-CD133 and anti-CD34 antibodies) to promote adhesion and proliferation of endothelial progenitor cells (EPCs). The in vitro study revealed that the adhesion force enabled the EPCs coated on glass slides to withstand flow-induced shear stress, so that allowing for the growth of the cells on the slides for 48 h. The in vivo experiment using a rabbit model in which the coated stents with different substrates were implanted showed that anti-CD34 and anti-CD133 antibody-coated stents markedly reduced the intima area and restenosis than bare mental stents (BMS) and gelatin-coated stents. Compared with the anti-CD34 antibody-coated stents, the time of cells adhesion was longer and earlier present in the anti-CD133 antibody-coated stents and anti-CD133 antibody-coated stents have superiority in re-endothelialization and inhibition of ISR. In conclusion, this study demonstrated that anti-CD133 antibody as a stent coating for capturing EPCs is better than anti-CD34 antibody in promoting endothelialization and reducing ISR.

The lack of a blood compatible synthetic interface is one of the largest unaddressed challenges in the field of biomaterials science. This technological shortcoming hinders the successful clinical application of small diameter vascular grafts and other cardiovascular devices such as stents and artificial heart valves. Therefore, intensive research activities are ongoing to develop polymer materials with improved blood compatibility. One attractive strategy to improve the blood compatibility of an interface is to design surfaces that promote the development of an endothelium, the monolayer of endothelial cells that line our native vasculature and is responsible for blood compatibility. This article describes the recent strategies that have been used to generate polymeric materials that promote the development of an endothelium, discusses shortcomings in the field, and proposes future directions of research that can be undertaken to design next generation polymeric biomaterial that promote endothelialization. (Figure presented.).

Background— Three major processes, constrictive vessel remodeling, intimal hyperplasia (IH), and retarded re-endothelialization, contribute to restenosis after vascular reconstructions. Clinically used drugs inhibit IH but delay re-endothelialization and also cause constrictive remodeling. Here we have examined halofuginone, an herbal derivative, for its beneficial effects on vessel remodeling and differential inhibition of IH versus re-endothelialization. Methods and Results— Two weeks after perivascular application to balloon-injured rat common carotid arteries, halofuginone versus vehicle (n=6 animals) enlarged luminal area 2.14-fold by increasing vessel size (adaptive remodeling; 123%), reducing IH (74.3%) without inhibiting re-endothelialization. Consistent with its positive effect on vessel expansion, halofuginone reduced collagen type 1 (but not type 3) production in injured arteries as well as that from adventitial fibroblasts in vitro. In support of its differential effects on IH versus re-endothelialization, halofuginone produced greater inhibition of vascular smooth muscle cell versus endothelial cell proliferation at concentrations ≈50 nmol/L. Furthermore, halofuginone at 50 nmol/L effectively blocked Smad3 phosphorylation in smooth muscle cells, which is known to promote smooth muscle cell proliferation, migration, and IH, but halofuginone had no effect on phospho-Smad3 in endothelial cells. Conclusions— Periadventitial delivery of halofuginone dramatically increased lumen patency via adaptive remodeling and selective inhibition of IH without affecting endothelium recovery. Halofuginone is the first reported small molecule that has favorable effects on all 3 major processes involved in restenosis.

Incomplete endothelialization and neointimal hyperplasia of injured arteries can cause acute and late stent thromboses. This work develops hybrid stent/biodegradable nanofibers for the local and sustained delivery of rosuvastatin to denuded artery walls. Biodegradable nanofibers were firstly prepared by dissolving poly(D,L)-lactide-co-glycolide and rosuvastatin in 1,1,1,3,3,3-hexafluoro-2-propanol. The solution was then electrospun into nanofibrous tubes, which were mounted onto commercially available bare-metal stents. The in vitro release rates of the pharmaceuticals from the nanofibers were determined using an elution method and a high-performance liquid chromatography assay. The experimental results thus obtained suggest that the biodegradable nanofibers released high concentrations of rosuvastatin for four weeks. The effectiveness of the local delivery of rosuvastatin in reducing platelets was studied. The tissue inflammatory reaction caused by the hybrid stents that were used to treat diseased arteries was also documented. The proposed hybrid stent/biodegradable rosuvastatin-loaded nanofibers contributed substantially to the local and sustainable delivery of a high concentration of drugs to promote re-endothelialization, improve endothelial function, reduce inflammatory reaction, and inhibit neointimal formation of the injured artery. The results of this work provide insight into how patients with a high risk of stent restenosis should be treated for accelerating re-endothelialization and inhibiting neointimal hyperplasia.

International audience; To better understand the effect of the internal thoracic artery on endothelial growth after open coronary endarterectomy, we designed an experimental test of the hypothesis that closing an endarterectomized artery by an arterial patch improves re-endothelialization. The two carotid arteries were endarterectomized in nine sheep and were randomly chosen for closure by native arterial femoral (ART) patch or polytetrafluoroethylene (PTFE) patch. Three animals were randomly chosen for sacrifice at 8, 15 and 21 days each. The endarterectomized segments were studied macroscopically and microscopically. The endarterectomized area covered with adhesive thrombus was more extensive in the PTFE than in the ART group (P=0.0117). In the ART group, the regenerated endothelium was normal and sprouted from the edges of both the endarterectomy and the arterial patch towards the central endarterectomized area. In the PTFE group, it sprouted from the edges of the endarterectomy and never reached the central endarterectomized area, where abnormal endothelium was observed. The endarterectomized area covered with normal endothelium was more extensive in the ART than in the PTFE group at 8 days, at 15 days, and 21 days (P

The use of cryopreserved arteries for vascular tissue engineering provides a promising way for vessel replacement. Unfortunately cryopreservation induces structural changes that strongly modify the mechanical properties and alter the thrombogenicity of the vessel after implantation. We present here a new procedure to treat the inner coating of cryopreserved arteries with poly(sodium-4-styrene sulfonate)/poly(allylamine hydrochloride) polyelectrolyte multilayers. We show that this treatment improves the mechanical properties of the cryopreserved vessel. It also allows the adhesion and spreading of endothelial cells so that the internal structure of the vessel closely resembles that of fresh arteries. Finally, we verify by PECAM-1 and von-Willebrand-factor (vWF) expression that this treatment preserves the phenotype of the endothelial cells. This study should open new routes towards the development of future, new biocompatible tissue substitutes allowing long-term functionality after implantation.

95% CI [0.9655-7.192]). Graft survival was significantly lower in the ECD group than in the IKG group (p1⁄4 0.003, HR: 3.773, 95% CI [1.540-9.240]). CONCLUSIONS: Transplantation with ECD grafts was associated with an increased incidence of surgical complications and a reduced graft survival. However, with a 5-year survival of 88.7 % for ECD, it remains an interesting alternative for selected patients given the organ shortage.