Mature vessel networks in engineered tissue promote graft-host anastomosis and prevent graft thrombosis.

Graft vascularization remains one of the most critical challenges facing tissue-engineering experts in their attempt to create thick transplantable tissues and organs. In vitro prevascularization of engineered tissues has been suggested to promote rapid anastomosis between the graft and host vasculatures; however, thrombotic events have been reported upon graft implantation. Here, we aimed to determine whether in vitro vessel maturation in transplantable grafts can accelerate vascular integration and graft perfusion and prevent thrombotic events in the grafts. To this end, endothelial cells and fibroblasts were cocultured on 3D scaffolds for 1, 7, or 14 d to form vasculature with different maturation degrees. Monitoring graft-host interactions postimplantation demonstrated that the 14-d in vitro-cultured grafts, bearing more mature and complex vessel networks as indicated by elongated and branched vessel structures, had increased graft-host vessel anastomosis; host vessel penetration into the graft increased approximately eightfold, and graft perfusion increased sixfold. The presence of developed vessel networks prevented clot accumulation in the grafts. Conversely, short-term cultured constructs demonstrated poor vascularization and increased thrombus formation. Elevated expression levels of coagulation factors, von Willebrand factor (vWF), and tissue factor (TF), were demonstrated in constructs bearing less mature vasculature. To conclude, these findings demonstrate the importance of establishing mature and complex vessel networks in engineered tissues before implantation to promote anastomosis with the host and accelerate graft perfusion.

NK cells in antibody-mediated rejection - Key effector cells in microvascular graft damage.

Antibody-mediated rejection (ABMR) stands as the major limitation to long-term transplant outcome. The immunologic understanding of ABMR continues to progress and has identified natural killer (NK) cells as key effector cells promoting and coordinating the immune attack on the graft microvascular endothelium. This review discusses the current concepts outlining the different ways that allow for NK cell recognition of graft endothelial cells which includes antibody-dependent as well as independent processes.

Pelvic Surgery in the Transplant Recipient: Important Considerations for the Non-transplant Surgeon.

PURPOSE OF REVIEW: Classically, kidney transplantation (KT) consists of heterotopic implantation of the renal graft in the iliac fossa with vascular anastomosis on the iliac vessel and reimplantation of the graft ureter in the bladder of the recipient. However, a wide range of variations exist in both vascular anastomosis and urinary diversion that the non-transplant surgeon should know. RECENT FINDINGS: For any pelvic surgery in a KT patient, the non-transplant surgeon should preoperatively evaluate the anatomy of the graft, its vascularization and its urinary tract. The transplant ureter should be identified and secured by preoperative JJ stenting whenever needed. For any surgery, maintenance and control of both immunosuppressive treatment and renal function is crucial. The advice or even the assistance of a transplant surgeon should be required because any damage to vascularization or urinary drainage of the renal graft could have dramatic and definitive consequences on graft function.

Troubleshooting Complex Vascular Cases in the Kidney Graft: Multiple Vessels, Aneurysms, and Injuries During Harvesting Procedures.

PURPOSE OF THE REVIEW: To update the most relevant literature regarding complex vascular cases in kidney transplant setting involving the graft, especially during the harvesting procedure and back-table preparation from the subsequent implant. RECENT FINDINGS: Challenging situations affecting the kidney graft such as multiple vessels, renal artery aneurysms, kidney anatomical anomalies, or major injuries do not contraindicate the transplant, but require an exhaustive graft viability assessment and several bench surgery techniques. Graft vessel conditioning in the back-table might include simple anastomosis between them, enlarging with venous patch or reconstruction with donor or synthetic grafts. Compared with conventional transplant, literature reports longer warm ischemia time (40 vs 32 min) and slightly increased rates of delayed graft function (10.3% vs 8.2%) and vascular complications (10.8% vs 8.1%), but similar graft and patient survival. Kidney graft vascular complex cases require exhaustive assessment, meticulous harvesting, good surgical technique in the bench table, and proper surgery in the recipient. Despite its complexity, vascular complex kidney transplant offers comparable outcomes in the long term to conventional population when technically well performed, with slightly increased rates of vascular complications and delayed graft function.

Troubleshooting Complex Vascular Cases in the Kidney Transplant Recipient: Vascular Anomalies, Challenging Vessel Diseases, and Procedural Disasters.

PURPOSE OF REVIEW: To update the most relevant literature regarding complex cases during kidney transplant setting that recipient presents by himself, especially during implantation surgery due to vascular diseases and/or urinary tract anomalies. RECENT FINDINGS: Increasing age of donors and recipients is leading to an increased complexity of kidney transplant implantation surgery. In addition, the high peripheral vascular disease prevalence worldwide increases difficulty of surgery and decreases long-term outcomes as well. Moreover, it also increases transplant morbidity and mortality, both overall and cardiovascular, and finally clearly decreases graft survival. However, dialysis alternative has even worse outcomes in terms of mortality, with a proportional risk of death 2.66 higher compared with transplanted patients. Aorto-iliac prosthesis and 3rd and 4th transplants in occupied iliac fossae do also represent a challenging situation with a clearly increased morbidity and mortality. In some of those particular conditions, orthotopic kidney transplant technique is an alternative with good functional and survival outcomes, but not exempt of complications. Kidney transplant in vascular complex recipients has worse outcomes compared with conventional non-risky population. It remains a challenging surgical and medical procedure with higher morbidity and mortality, and decreased graft survival. However, dialysis mortality is still even greater and a transplant attempt might be justified. Orthotopic kidney transplant technique might play a role in selected patients with aorto-iliac unworkable segments or even in patients with special urinary tract conditions.

Arterial reconstruction using the donor's gonadal vein in living renal transplantation with multiple renal arteries: a case report and a literature review.

BACKGROUND: Arterial reconstruction is one of the paramount procedures in kidney transplantation (KT) and greatly important if the procured kidney has multiple renal arteries (MRA). Despite various established techniques for arterial reconstruction, sometimes, the surgeon finds performing arterial anastomoses challenging in case of MRA. In our case, the donor's gonadal vein and recipient's internal iliac artery graft were used for arterial anastomoses, and 3 years after KT, the allograft did not present vascular complications. CASE PRESENTATION: A 34-year-old man underwent ABO-incompatible preemptive living KT. The allograft had three renal arteries and four renal veins. After donor nephrectomy, arterial reconstruction was performed on a back table. These arteries were reconstructed into one piece using the recipient's internal iliac artery graft. The two arteries at the middle of the renal hilum were reconstructed using the conjoined method. As the superior renal artery was too short to anastomose, the donor's gonadal vein was used for extension. The internal iliac artery graft was anastomosed to the original internal iliac artery. Intraoperative Doppler ultrasonography revealed that the blood flow in each renal artery was adequate, resulting in sufficient blood flow throughout the allograft. The allograft function was maintained with a serum creatinine level of approximately 0.9 mg/dL without vascular complications 3 years after KT. CONCLUSIONS: The donor's gonadal vein can be a candidate for extension of the renal artery in the allograft with MRA. Further follow-up is needed for the assessment of long-term outcomes.

Renal vascular resistance is increased in patients with kidney transplant.

BACKGROUND: Despite improvement in short-term outcome of kidney transplants, the long-term survival of kidney transplants has not changed over past decades. Kidney biopsy is the gold standard of transplant pathology but it's invasive. Quantification of transplant blood flow could provide a novel non-invasive method to evaluate transplant pathology. The aim of this retrospective cross-sectional pilot study was to evaluate positron emission tomography (PET) as a method to measure kidney transplant perfusion and find out if there is correlation between transplant perfusion and histopathology. METHODS: Renal cortical perfusion of 19 kidney transplantation patients [average time from transplantation 33 (17-54) months; eGFR 55 (47-69) ml/min] and 10 healthy controls were studied by [15 O]H2O PET. Perfusion and Doppler resistance index (RI) of transplants were compared with histology of one-year protocol transplant biopsy. RESULTS: Renal cortical perfusion of healthy control subjects and transplant patients were 2.7 (2.4-4.0) ml min- 1 g- 1 and 2.2 (2.0-3.0) ml min- 1 g- 1, respectively (p = 0.1). Renal vascular resistance (RVR) of the patients was 47.0 (36.7-51.4) mmHg mL- 1min- 1g- 1 and that of the healthy 32.4 (24.6-39.6) mmHg mL- 1min-1g-1 (p = 0.01). There was a statistically significant correlation between Doppler RI and perfusion of transplants (r = - 0.51, p = 0.026). Transplant Doppler RI of the group of mild fibrotic changes [0.73 (0.70-0.76)] and the group of no fibrotic changes [0.66 (0.61-0.72)] differed statistically significantly (p = 0.03). No statistically significant correlation was found between cortical perfusion and fibrosis of transplants (p = 0.56). CONCLUSIONS: [15 O]H2O PET showed its capability as a method in measuring perfusion of kidney transplants. RVR of transplant patients with stage 2-3 chronic kidney disease was higher than that of the healthy, although kidney perfusion values didn't differ between the groups. Doppler based RI correlated with perfusion and fibrosis of transplants.

Co-Transplantation of Nanofat Enhances Neovascularization and Fat Graft Survival in Nude Mice.

BACKGROUND: Autologous fat grafting is commonly used for soft-tissue augmentation and reconstruction. However, this technique is limited by a high rate of graft absorption. Thus, approaches to improve fat graft survival that promote neovascularization are of great interest. Nanofat has several beneficial features that may render it more suitable for clinical applications than other stem-cell based approaches. OBJECTIVES: We aimed to determine whether nanofat could enhance new vessel formation and improve the long-term retention of fat grafts. METHODS: Nanofat was processed via mechanical emulsification and filtration. Fat grafts were transplanted subcutaneously under the scalps of nude mice with different nanofat volumes or without nanofat. The grafted fat was dissected 12 weeks after transplantation. Graft weight and volume were measured, and histological evaluations, including capillary density measurement, were performed. RESULTS: The co-transplantation of fat with nanofat showed higher graft weight and volume retention, better histological structure, and higher capillary density compared to that in controls. However, there were no significant differences between the two nanofat volumes utilized. CONCLUSIONS: Nanofat can enhance neovascularization and improve fat graft survival, providing a potential clinically viable approach to fat graft supplementation in plastic and reconstructive surgery.

Clinical Assessment of Reconstruction Involving Gastric Pull-Up Combined with Free Jejunal Graft After Total Pharyngolaryngoesophagectomy.

BACKGROUND: Total pharyngolaryngoesophagectomy (PLE) is used as a curative treatment for synchronous laryngopharyngeal and thoracic esophageal cancer or for multiple cancers in the cervical and thoracic esophagus. Gastric pull-up is commonly used after PLE, but postoperative complications are common. The present study evaluated these procedures in patients with esophageal cancer. METHODS: Fourteen patients (7 with synchronous pharyngeal and thoracic esophageal cancer, 4 with synchronous cervical and thoracic esophageal cancer, and 3 with cervicothoracic esophageal cancer) underwent reconstructive surgery after PLE involving gastric pull-up combined with free jejunal graft between 2004 and 2015. RESULTS: Esophagectomy via right thoracotomy was performed in 9 patients, and transhiatal esophagectomy was used in 5. The posterior mediastinal route was used in 13 patients, excluding one patient with early gastric cancer. Interposition of a free jejunal graft included microvascular anastomosis using two arteries and two veins in all patients. Anastomotic leakage and graft necrosis did not occur in any of the 14 patients who underwent the above surgical procedures. Tracheal ischemia close to the tracheostomy orifice occurred in 4 patients (28.6%), but none of these patients developed pneumonia. No hospital deaths were recorded. CONCLUSIONS: The results indicate that gastric pull-up combined with free jejunal graft is a feasible reconstructive surgery after PLE. This procedure is a promising treatment strategy for synchronous pharyngeal and thoracic esophageal cancer or multiple cancers in the cervical and thoracic esophagus. Larger series are needed to show the distinct advantages of this procedure in comparison with conventional methods of reconstruction after PLE.

Applications of Burow's Grafts in the Reconstruction of Mohs Micrographic Surgery Defects.

BACKGROUND: Surgical defects in anatomically challenging locations, such as near free margins or crossing cosmetic subunits, may present reconstructive challenges to the dermatologic surgeon. For selected defects, Burow's grafts may produce functional and aesthetic results in a single operative session. OBJECTIVE: To describe the applications of the Burow's graft technique for the repair of defects after Mohs micrographic surgery. METHODS: An institutional review board-approved retrospective database review of surgical defects repaired with Burow's grafting after Mohs micrographic surgery at the Medical University of South Carolina was performed. The general technique of Burow's grafting is described, emphasizing proper graft sizing and direction of tension vectors. Varying anatomic locations and defect types are presented, with site-specific considerations and operative photographs. RESULTS: Burow's grafting provides ideal color and textural match, preserves subunit boundaries, results in a compact single-site wound, and may avoid complications of alternate repair choices. The tension vectors produced in closing the graft's harvest site may be designed to prevent distortion of free margins. Burow's grafting may be combined with hinge flaps to repair deep or avascular defects. CONCLUSION: Burow's grafts are reproducible, aesthetic, and useful reconstructive choices for a variety of surgical wounds.

Microvascular Tissue Transfers for Midfacial and Anterior Cranial Base Reconstruction.

Reconstruction of a midfacial defect can represent a difficult challenge for the plastic surgeon. Although many midfacial deformities have traumatic or congenital origins, the vast majority of head and neck defects occur after resection of malignant head and neck neoplasms. Autogenous reconstruction is now routinely performed for larger, complex defects resulting from surgical resection or trauma. In this study, the authors present 27 patients with midfacial defects reconstructed with free flaps. Twenty-two of the defects were created by surgical ablation of cancer (maxillectomy) and the others were traumatic. The maxillectomy defects were classified into 4 according to the classification proposed by Cordeiro. Eighteen of the patients were male and 9 were female. Twenty-nine free flaps were performed. Six different types of flaps including radial forearm flap, vertical rectus abdominis (VRAM) flap, anterolateral thigh (ALT) flap, tensor fasciae latae (TFL) flap, fibula osteocutaneous flap, and iliac osteocutaneous flap were accomplished. Types I and II defects were reconstructed with radial forearm flap. Type III defects were reconstructed with VRAM and ALT. Type IV defects were reconstructed with VRAM and TFL. Two patients underwent a second flap reconstruction due to recurrent disease (9.1%). Average patient age was 53.1 years. Free-flap survival was 100%. Free tissue transfer is the method of choice in midfacial reconstruction. Following a reconstructive algorithm is useful in the decision-making process for patient evaluation and treatment. Every reconstructive microsurgeon might have different experiences with different flaps. Therefore, the algorithm for flap choices is not universal among surgeons.

Targeted complement inhibition and microvasculature in transplants: a therapeutic perspective.

Active complement mediators play a key role in graft-versus-host diseases, but little attention has been given to the angiogenic balance and complement modulation during allograft acceptance. The complement cascade releases the powerful proinflammatory mediators C3a and C5a anaphylatoxins, C3b, C5b opsonins and terminal membrane attack complex into tissues, which are deleterious if unchecked. Blocking complement mediators has been considered to be a promising approach in the modern drug discovery plan, and a significant number of therapeutic alternatives have been developed to dampen complement activation and protect host cells. Numerous immune cells, especially macrophages, develop both anaphylatoxin and opsonin receptors on their cell surface and their binding affects the macrophage phenotype and their angiogenic properties. This review discusses the mechanism that complement contributes to angiogenic injury, and the development of future therapeutic targets by antagonizing activated complement mediators to preserve microvasculature in rejecting the transplanted organ.

Atrioventricular conduction disturbances immediately after hepatic graft reperfusion and their outcomes in patients undergoing liver transplantation.

Hemodynamic perturbation during hepatic graft reperfusion in patients undergoing liver transplantation (LT) is challenging and is frequently accompanied by bradyarrhythmia and even asystole. However, detailed data on electrocardiographic (ECG) changes during reperfusion are almost nonexistent, although the correct diagnosis by record is important for the treatment. We aimed to identify ECG rhythm disturbances during graft reperfusion and to investigate risk factors and outcomes. Data from 1065 consecutive patients who underwent adult LT were analyzed. The incidence, type, and detailed characteristics of ECG changes immediately after graft reperfusion were assessed using an electronically archived intraoperative ECG database. We analyzed risk factors, postoperative outcomes including major cardiovascular events, 30-day and 1-year mortalities of recipients based on the occurrence of atrioventricular (AV) block, and asystole during reperfusion. The typical pattern of postreperfusion bradyarrhythmia was progressive PR interval prolongation until a Mobitz type 1 AV block occurred. The overall incidence of AV block was 5.0% (53/1065), and 30.2% of them (16/53) had initiated as AV block and then progressed into ventricular asystole. Fulminant hepatic failure was a significant predictor for occurrence of AV block (odds ratio [OR], 7.20; 95% confidence interval, 3.38-15.32; P < 0.001). Patients with AV block showed significantly higher incidence of postoperative major cardiovascular events (P < 0.001) and 30-day mortality (P = 0.002) than those without AV block, whereas the 1-year mortality was not different between the 2 groups (P = 0.10). The postreperfusion asystole was consistently preceded by a Mobitz type 1 AV block. The occurrence of AV block and asystole appears to be an important prognosticator. Therefore, maintaining an optimal range of physiological status and gradual unclamping of the vena cava to avoid sudden atrial distension are recommended in high-risk patients during reperfusion period. Liver Transplantation 22 956-967 2016 AASLD.

Assessment of an Alternative to the Uterine Vein for Venous Drainage in Human Uterine Transplantation: A Case Series Following Laparoscopic Hysterectomy.

BACKGROUND/AIMS: To determine an alternative to the uterine vein, considering the utero-ovarian vein (UOV) for venous drainage in human uterine transplantation. METHODS: A case series of 10 total laparoscopic hysterectomies was conducted for benign indications and a vascular study was performed ex vivo on the surgical specimen, demonstrating ipsilateral and contralateral flow between the uterine artery (UA) and UOV visualizing anastomoses between these vessels. The flow pattern was documented using heparinized saline and illustrated through fluoroscopy using Isovue-300 dye. RESULTS: Successful cannulation of UA was accomplished in all 10 cases. Ipsilateral flow between the UA and UOV was demonstrated in all except one case, and contralateral flow was observed. Due to the long interval between the time of specimen retrieval and vascular study, the time to cannulation limited the ability to demonstrate ipsilateral and contralateral flow in 2 cases. CONCLUSION: Uterine transplantation has become a viable option for women with absolute uterine factor infertility. However, this surgery requires extensive surgical dissection, and the surgical retrieval of the uterine vein proposes a challenge. We present a potential option for venous drainage in uterine transplant surgery, considering the UOV for venous drainage as an alternative to the uterine vein and a possibility for minimally invasive approach.

Primary vascularization of allografts governs their immunogenicity and susceptibility to tolerogenesis.

We investigated the influence of allograft primary vascularization on alloimmunity, rejection, and tolerance in mice. First, we showed that fully allogeneic primarily vascularized and conventional skin transplants were rejected at the same pace. Remarkably, however, short-term treatment of mice with anti-CD40L Abs achieved long-term survival of vascularized skin and cardiac transplants but not conventional skin grafts. Nonvascularized skin transplants triggered vigorous direct and indirect proinflammatory type 1 T cell responses (IL-2 and IFN-γ), whereas primarily vascularized skin allografts failed to trigger a significant indirect alloresponse. A similar lack of indirect alloreactivity was also observed after placement of different vascularized organ transplants, including hearts and kidneys, whereas hearts placed under the skin (nonvascularized) triggered potent indirect alloresponses. Altogether, these results suggest that primary vascularization of allografts is associated with a lack of indirect T cell alloreactivity. Finally, we show that long-term survival of vascularized skin allografts induced by anti-CD40L Abs was associated with a combined lack of indirect alloresponse and a shift of the direct alloresponse toward a type 2 cytokine (IL-4, IL-10)-secretion pattern but no activation/expansion of Foxp3(+) regulatory T cells. Therefore, primary vascularization of allografts governs their immunogenicity and tolerogenicity.

An alternative graft fixation technique for scaphoid nonunions treated with vascular bone grafting.

PURPOSE: To present our experience with vascularized bone grafting based on the 1,2-intercompartmental supraretinacular artery for the management of established scaphoid nonunion and to investigate the efficacy of graft immobilization with a combination of Kirschner wires and transarticular external fixation. METHODS: A retrospective chart and radiographic review was conducted for patients with the diagnosis of scaphoid nonunion of the proximal pole or the waist treated with the 1,2-intercompartmental supraretinacular artery-based vascularized graft and fixed with a combination of Kirschner wires and transarticular external fixation between 2007 and 2011. RESULTS: We observed 23 consecutive patients for a mean of 34 ± 4 months. All patients were males with mean age of 25 ± 5 years. All patients had scaphoid nonunion and associated humpback deformity. The mean duration of nonunion was 7 ± 1 months. All scaphoid nonunions united after the index procedure at a mean of 10 ± 1 weeks. Two patients had avascular necrosis of the proximal pole based on the preoperative magnetic resonance imaging findings. After surgery, deformity correction was achieved in all patients, as recorded by the decrease in the lateral intrascaphoid angle and the increase in the dorsal scaphoid angle. At the last follow-up, no patients reported wrist pain. The mean Disabilities of the Arm, Shoulder, and Hand score improved significantly from 32 ± 12 before the operation to 5 ± 3 at the last postoperative visit. All patients showed statistically significant improvement in the range of motion and the grip strength of the involved wrist. CONCLUSIONS: The results of this study support the combined use of Kirschner wires and transarticular external fixation for fixation of a 1,2-intercompartmental supraretinacular artery-based vascular bone graft in the treatment of scaphoid nonunions. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

[The anatomical basis of the formation of the pedicled bone grafts on the upper extremity].

The study of the vascular bed of the upper extremities was performed by the method of anatomical preparation of 24 formalin-fixed cadaver specimens from 5 men and 7 women and by the injection of black latex into the arterial bed of 4 male and 4 female cadavers (16 specimens). The arteries, directly feeding the bones, and the arteries that provide blood supply to the muscles, attached to the bones, were studied. M. pectoralis major, m. pronator teres, m. pronator quadratus, mm. lumbricalis and interosseus were examined. These studies were followed by the experimental surgeries during which bone grafts on vascular pedicle were formed and moved. It was found that the feeding arteries of the bone grafts on musculo-vascular pedicle were: on the clavicula--the branches of a. thoracoacromialis, on the brachium--muscular branches of a. brachialis, on the proximal parts of forearm bones--muscular branches of a. radialis and ulnaris, on the distal parts of forearm bones--the branches of a. interosseous anterior, on the metacarpal bones--the branches of aa. metacarpalis palmaris and dorsalis. The size of the bone transplants is determined by the size of the defect of recipient field and varies from 3 to 8 cm. The displacement of vascularised bone graft can be made over the distance from 4 to 8 cm.

[Impact of plasmapheresis on intraorgan blood flow of the transplanted kidney in the early postoperative period].

Kidney transplant is inevitably subjected to ischemic and reperfusion injury. In many cases, this is due to a violation of intraorgan hemodynamics. Severity of such damage can be reduced using different methods of extracorporeal hemocorrection. The aim of the study was to examine the intraorgan blood flow of kidney transplant and assess the impact of plasmapheresis on its primary function in the early postoperative period. Plasmapheresis with replacement from 1,25 to 3,5 liters of plasma was applied in 40 recipients of the Group 1; in 40 recipients of Group 2 plasmapheresis was not performed. High resistance index (Ri > 0,9) at low flow velocities in the interlobular arteries at the first day after surgery is an informative criterion for the diagnosis of acute tubular necrosis and indicates the inadequate blood supply of kidney. Plasmapheresis has promoted the normalization of renal hemodynamics. Immediate graft function in patients of Group 1 was observed in 36 patients, whereas only in 19 patients of Group 2. In the Group 1, there were no patients with primary non-functioning graft, while there were three such patients in Group 2. Thus, plasmapheresis in the early postoperative period, no later than 3-5 h after reperfusion of the graft, has a positive effect on the functional status of the transplanted kidney.

[One-stage retrosternal colonic esophagoplasty in treatment of patients with scar burn stricture of esophagus].

Esophagoplasty was done in 23 patients an average of 10.4±2.3 months after chemical burn of esophagus. It was necessary to perform 29 corrective operations in 18 cases for training to one-stage plastic surgery such as gastrostomy, resection of stomach, retrocolic gastrojejunostomy on short loop. One-stage esophagoplasty was done in 21 of 23 cases. Functionally the most unusable anastomosis was cervical esophageal-intestinal anastomosis side-to-side. The number of complications after esophagocoloplasty by using of right flank was less than after using of left flank (39.92% vs. 50% respectively).