Graft Adaptation Research Articles

Non-invasive assessment of the dynamics of change in the vascular bed in the buccal autograph during treatment of extended urethral strictures

The male urethral stricture disease treatment despite all successful achievements and treatment options still remains one of the most actual and complex problems of modern urology. The presence of prolonged urethral strictures complicated with such factors as expressed scared deformation, infection, fistulae, previous unsuccessful urethral interventions, total urethral obliteration require the use of two- or multistage operations. In the light of recent times, the improvement methods dedicated to buccal mucosa graft adaptation assessment and autotransplant microvascularity evaluation are very relevant nowadays. In this study we made an attempt to estimate the dermatoscopy role in objective assessment of buccal mucosa graft microvascular network after two staged substitutive urethroplasty.The analysis of graft microphotos made in different time periods after urethroplasty allows us to define the main thing. In our point of view, the absence of evaluation changes after 90–120 postoperative days allows us to estimate a correct time for the second stage of urethroplasty-tubularization. stages of microvasculature evolution.Considering the statement that microvasculature evolution is the evolution of its graft, we think that the correct research direction is to study microangiogenesis stimulation methods.

Double vertical interrupted suture for optimal adaptation and stabilization of free gingival graft around dental implants: a case report

BackgroundFree gingival graft is commonly used to augment the keratinized mucosa and vestibular depth around dental implants. The proper suturing technique is fundamental to achieve a successful result following free gingival graft. However, there are limited studies that focus on the details of the suturing methods to optimize graft adaptation. The purpose of this technical note is to describe a new suturing technique for optimal approximation and stabilization of free gingival graft around dental implants.Case presentationHere, we present a 53-year-old Persian female with peri-implantitis and lack of keratinized mucosa around mandibular implants who was a candidate for free gingival graft. A new suturing technique, double vertical interrupted suture, was conducted in the interimplant areas. In addition, the suspensory cross-mattress sutures were added to ensure the adaptation of the graft over the implants. The proposed suturing technique is useful for soft tissue augmentation around multiple implants with concave or uneven recipient bed.ConclusionThe present article describes a novel suturing technique for good adaptation and fixation of free gingival graft around dental implants.

Sox17 mediates adult arterial endothelial cell adaptation to hemodynamics

Sox17 is a critical regulator of arterial identity during early embryonic vascular development. However, its role in adult endothelial cells (ECs) are not fully understood. Sox17 is highly expressed in arterial ECs but not in venous ECs throughout embryonic development to adulthood suggesting that it may play a functional role in adult arteries. Here, we investigated Sox17 mediated phenotypical changes in adult ECs. To precisely control the temporal expression level of Sox17, we designed a tetracycline-inducible lentiviral gene expression system to express Sox17 selectively in cultured venous ECs. We confirmed that Sox17-induced ECs exhibit a gene profile favoring arterial and tip cell identity. Furthermore, in comparison to control ECs, Sox17-activated ECs under shear leads to greater expression of arterial markers and suppression of venous identity. These data suggest that Sox17 enables greater hemodynamic adaptability of ECs in response to fluid shear stress. Here, we also demonstrate key morphogenic behaviors of Sox17-mediated ECs. In both vasculogenic and angiogenic 3D fibrin gel studies, Sox17-mediated ECs prefer to form cohesive vessels with one another while interfering the vessel formation of the control ECs. Sox17-mediated ECs elicit hyper-sprouting behavior in the presence of pericytes but not fibroblasts, suggesting Sox17 mediated sprouting frequency is dependent on supporting cell type. Using a microfluidic chip, we also show that Sox17-mediated ECs maintain thinner diameter vessels that do not widen under interstitial flow like the control ECs. Taken together, these data showed that Sox17 mediated EC gene expression and phenotypical changes are highly modulated in the context of biomechanical stimuli, suggesting Sox17 plays a role in regulating the arterial ECs adaptability under arterial hemodynamics as well as tip cells behavior during angiogenesis and vasculogenesis. The results from this study may be valuable in improving vein graft adaptation to arterial hemodynamics and bioengineering microvasculature for tissue engineering applications.

The use of 3D ceramic block graft compared with autogenous block graft for rehabilitation of the atrophic maxilla: a randomized controlled clinical trial

BackgroundDental implant placement may require a bone graft for vertical and horizontal alveolar ridge augmentation. Due to its osteoconduction, osteoinductive, and osteogenesis, autogenous bone graft characteristics are considered the standard gold treatment. However, autografts can promote postoperative morbidity and implicate difficulties concerning the graft adaptation to the recipient's bone since it can eventually avoid gaps. To overcome these issues, this trial will compare the performance of Plenum® Oss 3Dβ fit, an alloplastic graft, and a 3D-printed patient-specific graft based on β-tricalcium phosphate to the autograft procedure.MethodsThis is a split-mouth randomized clinical study designed to evaluate the performance of personalized (patient-specific) bioceramic bone grafts (Plenum® Oss 3Dβ fit) for bone augmentation of the atrophic anterior maxilla in comparison to the autogenous bone graft. We hypothesize that the gain and maintenance of the grafted area volume and the quality of the newly formed bone tissue after eight months postoperative with the synthetic patient-specific graft will be superior to the autogenous bone graft. To assess the quantity and the quality of bone neoformation, volumetric and histological analyses will be performed.DiscussionThe fabrication of medical devices by additive manufacturing presents advantages over conventional manufacturing processes, mostly related to the precision of geometry and anatomy. Additionally, the osteoconductive proprieties of β-tricalcium phosphate enable this synthetic bone substitute as an alternative solution over autogenous graft for bone defect reconstruction. Thus, patient-specific bone grafts can potentially improve patient satisfaction, reducing the need for autogenous bone grafts, consequently avoiding implications related to this type of treatment, such as patient morbidity.Trial registrationThis study is registered in REBEC (Registro Brasileiro de Ensaios Clínicos): RBR-76wmm3q; UTN: U1111-1272-7773. Registration date: 14 September 2021.

Biodegradable external wrapping promotes favorable adaptation in an ovine vein graft model

Vein grafts, the most commonly used conduits in multi-vessel coronary artery bypass grafting surgery, have high intermediate- and long-term failure rates. The abrupt and marked increase in hemodynamic loads on the vein graft is a known contributor to failure. Recent computational modeling suggests that veins can more successfully adapt to an increase in mechanical load if the rate of loading is gradual. Applying an external wrap or support at the time of surgery is one way to reduce the transmural load, and this approach has improved performance relative to an unsupported vein graft in several animal studies. Yet, a clinical trial in humans has shown benefits and drawbacks, and mechanisms by which an external wrap affects vein graft adaptation remain unknown. This study aims to elucidate such mechanisms using a multimodal experimental and computational data collection pipeline. We quantify morphometry using magnetic resonance imaging, mechanics using biaxial testing, hemodynamics using computational fluid dynamics, structure using histology, and transcriptional changes using bulk RNA-sequencing in an ovine carotid-jugular interposition vein graft model, without and with an external biodegradable wrap that allows loads to increase gradually. We show that a biodegradable external wrap promotes luminal uniformity, physiological wall shear stress, and a consistent vein graft phenotype, namely, it prevents over-distension, over-thickening, intimal hyperplasia, and inflammation, and it preserves mechanotransduction. These mechanobiological insights into vein graft adaptation in the presence of an external support can inform computational growth and remodeling models of external support and facilitate design and manufacturing of next-generation external wrapping devices. Statement of significanceExternal mechanical support is emerging as a promising technology to prevent vein graft failure following coronary bypass graft surgery. While variants of this technology are currently under investigation in clinical trials, the fundamental mechanisms of adaptation remain poorly understood. We employ an ovine carotid-jugular interposition vein graft model, with and without an external biodegradable wrap to provide mechanical support, and probe vein graft adaptation using a multimodal experimental and computational data collection pipeline. We quantify morphometry using magnetic resonance imaging, mechanics using biaxial testing, fluid flow using computational fluid dynamics, vascular composition and structure using histology, and transcriptional changes using bulk RNA sequencing. We show that the wrap mitigates vein graft failure by promoting multiple adaptive mechanisms (across biological scales).

Mechanical and Structural Adaptation of the Pulmonary Root after Ross Operation in a Murine Model.

Background: The major limitation to the Ross operation is a progressive autograft dilation, possibly leading to reoperations. A murine model was created to evaluate pulmonary artery graft (PAG) adaptation to pressure overload. Methods: Lewis rats (n = 17) underwent heterotopic surgical implantation of a PAG, harvested from syngeneic animals (n = 17). A group of sham animals (n = 7) was used as a control. Seriated ultrasound studies of the PAG were performed. Animals were sacrificed at 1 week (n = 5) or 2 months (n = 15) and the PAG underwent mechanical and histopathological analyses. Results: Echography showed an initial increase in diameter (p < 0.001) and a decrease in peak systolic velocity (PSV). Subsequently, despite no change in diameter, an increase in PSV was observed (p < 0.01). After 1 week, the stiffness of the PAG and the aorta were similar, while at 2 months, the PAG appeared more rigid (p < 0.05). PAG’s histological analysis at 2 months revealed intimal hyperplasia development. The tunica media showed focal thinning of the elastic lamellae and normally distributed smooth muscle cells. Conclusions: We demonstrated a stiffening of the PAG wall after its implantation in systemic position; the development of intimal hyperplasia and the thinning of the elastic lamellae could be the possible underlying mechanism.

Update on thoracic endovascular aneurysm repair : New stent graft designs

In the last decade, new stent graft designs have evolved to tackle challenges in thoracic endovascular aortic repair. Aspecific focus on access vessel issues has led to the introduction of new low-profile endograft designs for most of the major products. The main objective of this article is to provide an overview of the available publications on new stent graft designs. Assessing recent publications on the major reiterations of thoracic endografts, benefits and drawbacks are discussed. Recent reiterations of major endografts for thoracic aortic endovascular repair have focused mainly on the development of low-profile devices. Through alterations on graft fabric as well as stent material and design, delivery systems were reduced in profile, thus, reducing access vessel complications or enabling an endovascular procedure altogether. Long-term data are already available for one endoprosthesis. Other refinements include insitu adaptation of the stent graft to the aortic arch curvature as well as the option of staged deployment to allow more precision and reduce manipulation close to supra-aortic branches. Especially in the case of low-profile endografts, preliminary and long-term results of access vessel complications are promising. In order to draw final conclusions as to how durable the results of aneurysm exclusion are, more long-term studies are warranted.

Echocardiographic assessment of chamber size and ventricular function during the first year after heart transplantation.

Detecting changes in ventricular function after orthotopic heart transplantation (OHT) using transthoracic echocardiography (TTE) is important but interpretation of findings is complicated by lack of data on early graft adaptation. We sought to evaluate echocardiographic measures of ventricular size and function the first year following OHT including speckle tracking derived strain. We also aimed to compare echocardiographic findings to haemodynamic parameters obtained by right heart catheterization (RHC). Fifty OHT patients were examined prospectively with TTE and RHC at 1, 6, and 12months after OHT. Left ventricle (LV) was assessed with fractional shortening, ejection fraction and systolic tissue velocities. Right ventricular (RV) evaluation included tricuspid annular plane systolic excursion (TAPSE), systolic tissue velocity (S´) and fractional area change (FAC). LV global longitudinal and circumferential strain and RV global longitudinal strain (GLS) and RV lateral wall strain (RVfree) were analysed. No relevant changes occurred in LV echocardiographic parameters, whereas all measures of RV function improved significantly during follow-up. There was an increase in TAPSE (12.4±3.3mm to 14.4±4.3mm, p<.01), FAC (36%±8% to 41%±8%, p<.01), RV GLS (-15.8%±4% to -17.8%±3.6%, p<.01), and RVfree (-15.5%±3.7% to -18.6%±3.6%, p<.001). Between 1 and 12months, pulmonary pressures decreased, whereas pulmonary vascular resistance did not. Stable OHT recipients reached steady state regarding LV function 1month after transplantation. In contrast, RV function displayed gradual improvement the first year following OHT, indicating delayed RV adaptation as compared to the LV. Improved RV function parameters were independent of invasively measured pulmonary pressures.

Outcomes of Application Two-Piece Microkeratome-Assisted Mushroom Keratoplasty

Purpose: to evaluate outcomes and to expose possible specific complications of two-piece mushroom keratoplasty.Patients and methods. A total of 9 patients (9 eyes) with corneal perforations and deep stromal opacities involving the Descemet membrane were undergone surgery. In all cases, preserved hypothermic corneoscleral buttons (in Borzenok– Moroz medium) for up to 5 days were used as donor material. The two-piece mushroom keratoplasty was performed using a microkeratome and vacuum trephines set in the variant proposed by M. Busin.Results. Success survival was obtained in 78 % of patients (7 out of 9 cases). Best spectaclecorrected visual acuity (BSCVA) 1 year after surgery averaged 0.54 ± 0.20. The average of corneal astigmatism was 3.41 ± 1.89 D. Endothelial cell density in 6 months after surgery was on average 2364 ± 236/mm2, and in 1 year — 2082 ± 228/mm2. A false chamber formation between separate parts of the graft as a specific complication was detected in 2 patients on 1 day after surgery. In one case it was eliminated by air re-injecting into the ocular anterior chamber. The second patient underwent conventional PKP due to the lack of graft adaptation. In addition, 1 patient also underwent conventional PKP as a result of postoperative crystalline infectious keratopathy, which is the non-specific complication of mushroom keratoplasty.Conclusion. The two-piece microkeratome-assisted mushroom keratoplasty is an effective method of surgical treatment of corneal perforations and deep stromal opacities involving the Descemet membrane.

Extracellular signal-regulated kinase inhibition prevents venous adaptive remodeling via regulation of Eph-B4.

Vein graft adaptation (VGA) is a process that vein as a vascular graft conduits in arterial reconstructive surgery; VGA can lead to postoperative vein graft stenosis (VGS) and complications after coronary artery bypass graft and other peripheral artery bypass surgeries. VGA is characterized by vein graft loss the venous features without exhibiting arterial features; furthermore, the activation of ERK inhibited the maintenance of venous properties of the vein graft. We hypothesized that ERK inhibition can affect vein VGS through regulating the expression of EphB4. Rat vein transplantation model was established using wild-type and EphB4+/- Sprague-Dawley rats. Hematoxylin-eosin, Masson, Verhoeff, actin staining, and immunohistochemistry were applied to observe the structure of the vein grafts. Vascular smooth muscle cells (VSMCs) were isolated from the vein and vein grafts. Western blotting was used to determine the expression of p-ERK1/2 and EphB4, and immunofluorescence was applied to detect the expression and location of EphB4. Cell wound scratch assay and CCK8 assay were used to determine the migration and proliferation of VSMCs. Real-time polymerase chain reaction was used to determine the mRNA expression of EphB4. Western blotting in vein sample and vein graft sample detected p-ERK1/2 and ERK1/2 expression in both EphB4+/+ and EphB4+/- rats. The expression of p-ERK was increased in vein graft compared to vein. Immunofluorescence in VSMCs form EphB4+/+ and EphB4+/- rats detected EphB4 expression in both cells, and the expression of EphB4 was increased in VSMCs form EphB4+/+ rats. SCH772984 reduces the proliferation and migration of VSMCs. Inhibition of ERK suppressed the increase of vein graft wall thickness, and the expression of collagen fibers, elastic fibers, and α-actin was decreased. Vein graft from EphB4+/- rats reduces the expression of EphB4, and SCH772984 suppressed the decrease of EphB4 in vivo. Vein graft from EphB4+/- rats increased the expression of EphB4, and SCH772984 suppressed the increase of EphB4 in vivo. The inhibition of ERK1/2 suppressed the process of VGS by decreasing the proliferation of VSMCs. The ERK-inhibitor SCH772984 suppressed the level of VGS by extending the time of EphB4 expression during the process of VGA, thus maintaining the venousization of vein graft. The mechanism may be that the inhibitor SCH772984 suppresses the level of VGS by extending the time of EphB4 expression during the process of VGA. Therefore, our research provides a new target of VGS treatment by inhibiting the expression of ERK1/2 through the process of VGA.

Fluorescent PSC-Derived Cardiomyocyte Reporter Lines: Generation Approaches and Their Applications in Cardiovascular Medicine.

Simple SummaryUnderstanding how heart muscle cells function and developing new strategies for repairing the damaged heart are important challenges for tackling heart disease. Human cells from the heart are required in the laboratory for these investigations, but are difficult to obtain in large numbers from patients. As an alternative, stem cells can be used which can be cultured indefinitely in the laboratory and then turned into heart muscle cells. The current methods lead to a mixture of cell types, belonging to the different regions of the heart, creating difficulties when trying to understand the biology of a particular area of the heart, or for future applications when these stem cell-derived cell types are used to repair the heart. Genetic modification of stem cells provides a solution to this problem, as these techniques allow fluorescent markers, so-called reporters, to be inserted into key genes that are active in the different cell types. The different coloured reporters thus allow the identification and purification of specific cell types. In this review, we discuss the various methods that can be used to establish these reporter systems and highlight their applications in different aspects of cardiovascular medicine.Recent advances have made pluripotent stem cell (PSC)-derived cardiomyocytes an attractive option to model both normal and diseased cardiac function at the single-cell level. However, in vitro differentiation yields heterogeneous populations of cardiomyocytes and other cell types, potentially confounding phenotypic analyses. Fluorescent PSC-derived cardiomyocyte reporter systems allow specific cell lineages to be labelled, facilitating cell isolation for downstream applications including drug testing, disease modelling and cardiac regeneration. In this review, the different genetic strategies used to generate such reporter lines are presented with an emphasis on their relative technical advantages and disadvantages. Next, we explore how the fluorescent reporter lines have provided insights into cardiac development and cardiomyocyte physiology. Finally, we discuss how exciting new approaches using PSC-derived cardiomyocyte reporter lines are contributing to progress in cardiac cell therapy with respect to both graft adaptation and clinical safety.

Clinical correlation of vein graft adaptation

While we revascularize our patients using venous bypass, we seldom think of the complex process that is set into place the minute that we remove arterial control and reperfuse the limb. Yet once arterial blood enters the venous graft, adaptation of the graft to its new environment is triggered. This adaptation plays a significant role in graft patency, clinical durability, and ultimate clinical outcomes. Although vein graft remodeling has been widely studied in both animal and clinical models much about this process remains poorly understood.

Evaluating the long-term patient satisfaction, esthetic harmony, and creeping attachment levels in patients treated with gingival augmentation surgery: A retrospective study

Objective: Free gingival grafts (FGGs) are commonly used for increasing the keratinized tissue and root coverage in gingival recessions (GRs). The aim of this retrospective study was to evaluate the long-term patient satisfaction ratings, esthetic adaptation of graft, and creeping attachment (CA) levels after FGG surgery. Methods: Thirty-five surgical areas from thirty patients with Miller Class I, II, and III GRs were included in the study. GRs were treated with FGGs, and palatal donor area was covered with the same surgical pack in all patients. Gingival index (GI), bleeding on probing (BoP), probing depth, plaque index (PI), vertical and horizontal GRs (VGR and HGR, respectively), keratinized gingiva width (KGW), keratinized gingiva thickness (KGT), CA, evaluating the esthetic harmony with modified Manchester Scar Scale (mMSS), and patient satisfactory ratings were collected at the 1st month, 6th month, and 5th year control. Descriptive statistical methods as well as distribution of the data were evaluated by the Shapiro–Wilk test, the Friedman test was used in comparison of three and more dependent groups, and the Wilcoxon test was used in comparison of two dependent groups. Results: The mean follow-up period was 76.91 ± 7.60 months. The last control measurements of clinical parameters such as GI, PI, BoP, VGR, HGR, and mMSS measurements were statistically significantly lower than the baseline and 1st-month measurements (P

Preoperative Planning for Physician-Modified Endografts Using a Three-Dimensional Printer.

The medical uses of three-dimensional (3D) printing are evolving at a rapid pace. The current roles and the future outlooks of this technology for physician-modified endovascular graft (PMEG) in patients with juxtarenal aneurysm are discussed. Fenestrations of PMEG are designed taking into account the geometry of the stent graft. Designing of such stent grafts is extremely complicated, especially when PMEG is planned for the angulated portion of the aorta. A 3D model enables the designing of branch fenestrations, with consideration for the geometrical adaptation of the stent graft in a complex aortic anatomy. With the aid of 3D-printing technology, patients with juxtarenal aortic pathologies can be treated using fenestrated stent grafts, preserving the vital organ circulation and securing a robust length of proximal sealing zone.

Utilizing autologous growth factors enriched bone graft matrix (sticky bone) and Platelet rich fibrin (PRF) membrane to enable dental implant placement: A case report

Introduction: Dental implants are the most innovative and superior treatment in dentistry, and are widely used. However, the intended implant site may be inappropriate due to the poor bone quality or insufficient bone volume. When extensive loss of alveolar bone is encountered it presents a complex challenge for reconstruction. Numerous augumentation technique are used for alveolar reconstruction and to create sufficient bone volume for placement of endosseous implants. In order to accelerate healing of bone graft over the bony defect, numerous techniques utilizing platelet and fibrinogen concentrations have been introduced in the literature. Sticky bone provides stabilizationof bone graft in the defect, and therefore, accelerates tissue healing and minimizes bone loss during healing period. Due to formation of homogenous mass of bone graft particles, handling and adaptation of bone graft becomes easy. The use of sticky bone also avoids complex ridge augumentation procedures. Aim: The aim of this case report is to demonstrate the use of sticky bone and autologous PRF membrane in hard tissue regeneration and maintenance of volume of alveolar ridge to enable dental implant placement. Material and Methods: Ridge augmentation was done in defect using sticky bone formed by cera bone granules of particle size 0.5-1.0 mm and PRF membranes. Results: Sufficient bone volume was achieved through GBR as shown by comparing presurgical and post 3months CT and clinically it can be seen at second stage surgery done after 3 months. Conclusion: The result suggested that GBR with autologous PRF membranes is sufficient for augmentation of localised alveolar ridge defects with conjunction with sticky bone. Sticky bone provides stabilization of bone graft in defect and improves handling properties and PRF membranes act as barrier membrane as well as source of accelerated growth factor release. Keywords: Dental implant, Sticky bone, and Platelet rich fibrin (PRF) membrane.

Physiologic type reconstruction in upper gastrointestinal caustic strictures

The authors discuss their experience in the surgical treatment of caustic stenosis in the upper gastrointestinal tract. They present operative solutions using isoperistaltic transverse colonic segment in oesophageal stenosis caused by gastric outlet obstruction, or when these two presented together. Further indications for the above were bronchial or tracheo-oesophageal fistulas and oesophageal perforation. Late adaptation of the colonic grafts were measured by radiokinematography and histochemistry. The overall morbidity was 4.9%. Postoperative salivary fistulas closed spontaneously. Late postoperative complications (13.5%) were treated successfully. The multihaustral motility of the graft prevented the reflux, while the altered mucopolysaccharides of the colonic mucosa prevented the ulcer formation. Orv Hetil. 2019; 160(16): 613-618.

Tratamento de fratura Blowout com auxílio de vídeo-cirurgia

ABSTRACT Posterior fractures of the orbital floor are challenging, since an incomplete visualization of the defect through conventional surgical accesses may compromise the surgical outcome. The use of the endoscope as an auxiliary method during orbital reconstructions may be considered as a tool of considerable importance, mainly due to the visualization of the whole extension of fracture and adaptation of meshes or bone grafts. This study aims to report a clinical case of a patient diagnosed with extensive blowout fracture showing diplopy, enophthalmos, and ophthalmoplegia in supraversion, who underwent a subciliary approach combined with transantral video assisted surgery. There were no intercurrences on the procedure. Currently, patient has 1 year of follow up, with reestablished orbital function and architecture.

Versican is differentially regulated in the adventitial and medial layers of human vein grafts.

Changes in extracellular matrix proteins may contribute significantly to the adaptation of vein grafts to the arterial circulation. We examined the production and distribution of versican and hyaluronan in intact human vein rings cultured ex vivo, veins perfused ex vivo, and cultured venous adventitial and smooth muscle cells. Immunohistochemistry revealed higher levels of versican in the intima/media compared to the adventitia, and no differences in hyaluronan. In the vasa vasorum, versican and hyaluronan associated with CD34+ progenitor cells. Culturing the vein rings for 14 days revealed increased versican immunostaining of 30–40% in all layers, with no changes in hyaluronan. Changes in versican accumulation appear to result from increased synthesis in the intima/media and decreased degradation in the adventitia as versican transcripts were increased in the intima/media, but unchanged in the adventitia, and versikine (the ADAMTS-mediated cleavage product of versican) was increased in the intima/media, but decreased in the adventitia. In perfused human veins, versican was specifically increased in the intima/media in the presence of venous pressure, but not with arterial pressure. Unexpectedly, cultured adventitial cells express and accumulate more versican and hyaluronan than smooth muscle cells. These data demonstrate a differential regulation of versican and hyaluronan in human venous adventitia vs. intima/media and suggest distinct functions for these extracellular matrix macromolecules in these venous wall compartments during the adaptive response of vein grafts to the arterial circulation.

A Rabbit Model of Durable Transgene Expression in Jugular Vein to Common Carotid Artery Interposition Grafts.

Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, intimal hyperplasia, and atherosclerosis. The goal of this article is to demonstrate a method for placing bilateral venous interposition grafts in a rabbit, then transducing the grafts with a gene transfer vector that achieves durable transgene expression. The method allows the investigation of the biological roles of genes and their protein products in normal vein graft homeostasis. It also allows the testing of transgenes for the activities that could prevent vein graft failure, e.g., whether the expression of a transgene prevents the neointimal growth, reduces the vascular inflammation, or reduces atherosclerosis in rabbits fed with a high-fat diet. During an initial survival surgery, the segments of right and left external jugular vein are excised and placed bilaterally as reversed end-to-side common carotid artery interposition grafts. During a second survival surgery, performed 28 days later, each of the grafts is isolated from the circulation with vascular clips and the lumens are filled (via an arteriotomy) with a solution containing a helper-dependent adenoviral (HDAd) vector. After a 20-min incubation, the vector solution is aspirated, the arteriotomy is repaired, and flow is restored. The veins are harvested at time points dictated by individual experimental protocols. The 28-day delay between the graft placement and the transduction is necessary to ensure the adaptation of the vein graft to the arterial circulation. This adaptation avoids rapid loss of transgene expression that occurs in vein grafts transduced before or immediately after grafting. The method is unique in its ability to achieve durable, stable transgene expression in grafted veins. Compared to other large animal vein graft models, rabbits have advantages of low cost and easy handling. Compared to rodent vein graft models, rabbits have larger and easier-to-manipulate blood vessels that provide abundant tissue for analysis.

Улучшение адаптации трансплантата и снижение астигматизма при сквозной кератопластике с использованием интраоперационной оптической когерентной томографии

Улучшение адаптации трансплантата и снижение астигматизма при сквозной кератопластике с использованием интраоперационной оптической когерентной томографии