Application of iPSCs derived pancreatic ß-like cells using pancreatic bio-scaffold.

This study aimed toengineer a pancreatic tissue. Intact rat pancreases were successfully decellularized, and were reseeded with human-induced pluripotent stem cells using different 2D and 3D culture growth factors. The differentiation process was assessed for the presence of a pancreas-like tissue. The histology and SEM analysis revealed cell attachment in all samples, except for the Exp4, and the Flow-cytometry provided 87% viability for the differentiated cells. In Exp1, PDX1 with the positive expression of 2.87±0.06 was dramatically higher than Exp2 with a 2.44±0.06 reaction. NGN3-reactions were 8±0.1 and 6.6±0.2 in Exp1 and Exp2 at P < 0.05, respectively. C-peptide with the expression of 7.5±0.7 in Exp3 was almost equal to that in Exp1 and Exp2. Glucagon (5.1±1) and PDX1 (3.2±0.82) in Exp3 indicated no significant difference. The significant upregulations of pancreatic endocrine markers (PDX1 and NGN3), and the cell-specific glucose transporter (GLUT2) were observed in the differentiated IPCs in the 3D culture of Exp2 after 21 days. The highest insulin and C-peptide concentrations were observed in Exp2. In Exp3, insulin secretion in response to high glucose and 10 mM arginine was 42.43 ±6.34 µU/ml. A decellularized pancreas in the presence of hiPSCs and growth factors could be efficiently used as a natural scaffold.

In vivo application of decellularized rat colon and evaluation of the engineered scaffolds following 9 months of follow-up.

The aim of this study was to investigate the rat small intestine mesentery and colon as natural bio-reactors for rat colon-derived scaffolds. We decellularized eight whole rat colons by a perfusion-based protocol using 0.1% sodium dodecyl sulfate for 24 hr. The provided bio-scaffolds were examined by histological staining, scanning electron microscopy, and collagen and sulfated glycosaminoglycan quantification. Subsequently, we implanted 4 cm segments of the provided bio-scaffolds into two groups of animal models comprising tissue grafting into the mesenteric tissue (n: 10) and end-to-end anastomosis (n: 10) to the colon of host rats. Following 9 months of follow-up, we harvested the grafts and performed histological and immunohistochemical studies as well as real-time PCR evaluation for telomerase activity of the samples. Histological staining, scanning electron microscopy and protein content evaluation of the acellular tissues confirmed the complete removal of the cellular components and preservation of the extracellular matrix. Histopathological assessment of the implanted scaffolds was suggestive of a regenerative process in both groups. Moreover, immunohistochemical analysis of the samples confirmed the presence of smooth muscle cells, endothelial progenitor cells, and neural elements in both groups of grafted scaffolds. Our data confirmed the recellularization of the acellular colon grafts in both groups after 9 months of follow up. Also, the implanted tissues demonstrated different characteristics based on their implantation location. The outcomes of this investigation illustrate the capability of acellular tissues for in vivo application and regeneration.

Application of a novel bioreactor for in vivo engineering of pancreas tissue.

Type 1 diabetes is characterized by autoimmune destruction of pancreatic cells. Organ transplantation is an acceptable treatment for native organ failure. However, it is associated with several problems due to a number of reasons, such as the lack of appropriate donors and immunosuppression. In our present study, a novel model is presented for in vivo recellularization of acellular pancreas by implanting between the host pancreas and the adjacent omental flap. In this study, the pancreases were harvested and cannulated via the common bile duct and then, the scaffolds were acellularized by a detergent-based protocol. After that, the abdomens of 35 rats were opened and the spleen was extracted with the adjacent omentum, and placed outside the abdomen. The acellularized scaffold was stretched over the host pancreas and the omentum was wrapped around it to make a sandwich-like structure, which was then fixed with Chromic Sutures 6-0 and marked with Prolene 4-0 on four sides. All samples were biopsied at 14, 30, 60, 90, and 120 days post-transplantation. The result showed marked recellularization of acellularized pancreas with visible neovascularization and neoß-cells with minimal inflammatory response. This study provides a new approach to produces a normal-like pancreas by allograft transplantation for pancreas tissue engineering. We observed that in vivo transplantation of acellularized pancreas can promote recellularization, proliferation, and differentiation by blood circulation. These findings support that in vivo studies can contribute to finding faster solutions for the treatment of diabetes.

Decellularized Pancreas Matrix Scaffolds for Tissue Engineering Using Ductal or Arterial Catheterization.

INTRODUCTION: Diabetes is known as a worldwide disease with a great burden on society. Since therapeutic options cover a limited number of target points, new therapeutic strategies in the field of regenerative medicine are considered. Bioscaffolds along with islet cells would provide bioengineered tissue as a substitute for ß-cells. The perfusion-decellularization technique is considered to create such scaffolds since they mimic the compositional, architectural, and biomechanical nature of a native organ. In this study, we investigated 2 decellularization methods preserving tissue microarchitecture. METHODS: Procured pancreas from Sprague-Dawley rats was exposed to different percentages of detergent for 2, 4, and 6 h after cannulation via the common bile duct or aorta. RESULTS: High concentrations of sodium dodecyl sulfate (SDS), i.e., > 0.05%, resulted in tissue disruption or incomplete cell removal depending on the duration of exposure. In both methods, 6-h exposure to 0.05% SDS created a bioscaffold with intact extracellular matrices and proper biomechanical characteristics. Tissue-specific stainings revealed that elastic, reticular, and collagen fiber concentrations were well preserved. Quantitative findings showed that glycosaminoglycan content was slightly different, but hydroxyproline was in the range of native pancreas tissue. Dye infusion through ductal and vascular cannulation proved that the vascular network was intact, and scanning electron microscopy indicated a homogeneous porous structure. CONCLUSIONS: Using the detergent-based method, an effective and time-efficient procedure, a whole pancreas extracellular matrix bioscaffold can be developed that can be used as a 3D structure for pancreas tissue engineering-based studies and regenerative medicine applications.

Alleviation of Cyclophosphamide-induced Hemorrhagic Cystitis by Dietary Pomegranate: A Comparative Experimental Study With Mesna.

In this study, we investigated the effects of pomegranate on alleviating cyclophosphamide-induced hemorrhagic cystitis (HC). Initially, 16 Sprague-Dawley rats were allocated into 4 groups: group 1 (control), group 2 (CP) in which HC was induced by cyclophosphamide; group 3 (CP+M), HC-induced rats that received Mesna regimen, and group 4 (CP+P), which compromised rats that had been on a 14-day diet of pomegranate juice before HC induction. Cystometry was performed a few hours before euthanasia; after euthanasia, aortic blood samples and bladder tissue samples were obtained to perform TUNEL assay, and histopathologic and biochemical assessments. Urodynamic findings revealed that mean detrusor pressure in CP+P was significantly lower compared with that in CP and CP+M (P<0.05). Histopathologically, urothelium destruction and inflammation were lower in CP+P and CP+M compared with that in CP. Collagen destruction was less prominent in CP+P compared with that in CP and CP+M. Tissue and plasma levels of malondialdehyde were significantly lower in CP+P versus CP (P<0.05). Catalase activity and total protein thiol group levels in plasma and bladder tissue were higher in CP+P versus CP (P<0.05). The TUNEL positivity in CP+P was significantly weaker than that in CP, indicating less DNA fragmentation and apoptosis. Pomegranate's characteristics could significantly affect the inflammatory and destructive process of hemorrhagic cystitis.

Application of Human Acellular Breast Dermal Matrix (ABDM) in Implant-Based Breast Reconstruction: An Experimental Study.

BACKGROUND: The use of acellular dermal matrices (ABDM) has become more common for breast reconstruction to improve postoperative outcomes. We evaluated the efficacy of breast reconstruction by the application of human ABDM in a sheep model. METHODS: The sheep in group I (GI) (N = 4) underwent the following procedures on the right side: (1) breast reconstruction using human ABDM after total mastectomy, (2) human ABDM under the skin, near the breast area and on the left side, (3) fat injection and human ABDM after partial mastectomy, and (4) replacement of ABDM in the abdominal wall far from the breast. Sheep in group II (GII) (N = 4) underwent the following procedures. On the right side: (1) breast reconstruction using ABDM after total mastectomy, (2) replacement of ABDM under the skin, near the breast area, and on the left side, (3) application of vicryl synthetic mesh after partial mastectomy and (4) replacement of mesh under the skin, near the breast area. RESULTS: Histological evaluations of decellularized skin scaffolds demonstrated a collagen-based matrix with preserved ECM and complete nuclear removal. Histological evaluations of implanted ABDM demonstrated a viable matrix with fibroblast infiltration and revascularization in all follow-ups. The overall surgical complication rate was significantly lower in the ABDM implant under the skin and near the breast in both short- and long-term follow-ups. CONCLUSION: The results of this study demonstrated that the application of novel prepared ABDMs has promising outcomes for breast reconstruction to provide total coverage without the need for breast expansion before implant placement. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266.

Evaluating the role of autologous mesenchymal stem cell seeded on decellularized pericardium in the treatment of myocardial infarction: an animal study.

Inappropriate left ventricular remodeling following myocardial infarction (MI) can result in subsequent severe dysfunction. In this study, we tested the hypothesis that decellularized pericardium (DP) or seeded pericardial patch with autologous adipose-derived mesenchymal stem cells (ADMSCs) could be safely used in a MI scar and could improve heart function. Twelve rabbits were randomly divided into three equal groups. Four weeks after MI induction by ligation of the left anterior descending artery in 12 rabbits, animals of G1 (n = 4) received DP patch with labeled ADMSCs. DP patch was implanted in animals of G2 (n = 4). Rabbits of G3 (n = 4) remained without any intervention after MI induction (control group). Serial examinations including echocardiography, electrocardiography (ECG), scanning electron microscopy, histology and immunohistochemistry (IHC) were performed to evaluate the efficacy of the implanted scaffolds on recovery of the infracted myocardium. The results demonstrated that left ventricular contractile function and myocardial pathological changes were significantly improved in rabbits implanted with either DP or ADMSC-seeded pericardium. However, the seeded pericardium was more effective in scar repairing 2 months after the operation, IHC staining with Desmin and CD34 and positive immunofluorescence staining verified the differentiation of ADMSCs to functional cardiomyocytes. This approach may involve the application of autologous ADMSCs seeded on pericardial patch in an attempt to regenerate a contractible myocardium in an animal model of MI.

In vivo regeneration of bladder muscular wall using decellularized colon matrix: an experimental study.

BACKGROUND: Finding a proper scaffold for augmentation is a serious challenge in bladder tissue engineering. We hereby aimed to determine the histological aspects of a decellularized colon graft for bladder augmentation in healthy rats. METHODS: Rat colon tissues were decellularized using perfusion-based method. After partial cystectomy, bladders were grafted with a patch of decellularized colon. Bladder specimens were investigated in 12 rats at 1, 3, and 9 months postoperatively for further histological changes and immunohistochemistry analyses were also performed. RESULTS: One month after implantation, partial seeding of new cells was observed. After 3 months continuity of transitional epithelium of natural bladder on the decellularized grafted colon tissue was confirmed with histological and immunohistochemical examinations. All augmented bladders demonstrated a spherical shape without stone formation, necrosis or graft rejection. The presence of urothelium with similar morphology to the natural urothelium and visible blood vessels were found within 3 months of operation. All immunohistochemical markers (except markers of colonic stem cells) were expressed in biopsies obtained 3 months after surgery demonstrating a progressive vascular and smooth muscle cell infiltration into the graft after implantation. CONCLUSION: This study suggests that decellularized colon may provide a viable material for bladder augmentation in rats to pave the road for future applications of this natural collagen scaffold.

A novel technique for simultaneous whole-body and multi-organ decellularization: umbilical artery catheterization as a perfusion-based method in a sheep foetus model.

The aim of this study was to develop a method to generate multi-organ acellular matrices. Using a foetal sheep model have developed a method of systemic pulsatile perfusion via the umbilical artery which allows for simultaneous multi-organ decellularization. Twenty sheep foetuses were systemically perfused with Triton X-100 and sodium dodecyl sulphate. Following completion of the whole-body decellularization, multiple biopsy samples were taken from different parts of 21 organs to ascertain complete cell component removal in the preserved extracellular matrices. Both the natural and decellularized organs were subjected to several examinations. The samples were obtained from the skin, eye, ear, nose, throat, cardiovascular, respiratory, gastrointestinal, urinary, musculoskeletal, central nervous and peripheral nervous systems. The histological results depicted well-preserved extracellular matrix (ECM) integrity and intact vascular structures, without any evidence of residual cellular materials, in all decellularized bioscaffolds. Scanning electron microscope (SEM) and biochemical properties remained intact, similar to their age-matched native counterparts. Preservation of the collagen structure was evaluated by a hydroxyproline assay. Dense organs such as bone and muscle were also completely decellularized, with a preserved ECM structure. Thus, as shown in this study, several organs and different tissues were decellularized using a perfusion-based method, which has not been previously accomplished. Given the technical challenges that exist for the efficient generation of biological scaffolds, the current results may pave the way for obtaining a variety of decellularized scaffolds from a single donor. In this study, there have been unique responses to the single acellularization protocol in foetuses, which may reflect the homogeneity of tissues and organs in the developing foetal body.

Epidemiology of traumatic spinal cord injury in developing countries: a systematic review.

BACKGROUND/AIMS: To describe the epidemiology of spinal cord injury (SCI) in the developing world. METHODS: Developing countries were selected based on the definition proposed by the International Monetary Fund. A literature search was performed in July 2012 in Medline and Embase. Further article procurement was obtained via the reference lists of the identified articles, websites, and direct contact with the authors of the identified studies. We designed search strategies using the key words: SCI, epidemiology, incidence, and prevalence. According to the inclusion criteria, 64 studies from 28 countries were included. RESULTS: The incidence of SCI in developing countries is 25.5/million/year (95% CI: 21.7-29.4/million/year) and ranges from 2.1 to 130.7/million/year. Males comprised 82.8% (95% CI: 80.3-85.2) of all SCIs with a mean age of 32.4 years (95% CI: 29.7-35.2). The two leading causes of SCI were found to be motor vehicle crashes (41.4%; 95% CI: 35.4-47.4) and falls (34.9%; 95% CI: 26.7-43.1). Complete SCIs were found to be more common than incomplete injuries (complete SCI: 56.5%; 95% CI: 47.6-65.3; incomplete SCI: 43.0%; 95% CI: 34.1-52.0). Similarly, paraplegia was found to be more common than tetraplegia (paraplegia: 58.7%; 95% CI: 51.5-66.0; tetraplegia: 40.6%; 95% CI: 33.3-48.0). CONCLUSION: Through an understanding of the epidemiology of SCI in developing countries, appropriate preventative strategies and resource allocation may decrease the incidence and improve the care of these injuries.

Determinants of mortality in patients with traumatic brain injury.

BACKGROUND: We aimed to determine factors associated with mortality rates in patients with traumatic brain injury (TBI). METHODS: Registered data of a national trauma project conducted in eight major cities in Iran during a five-year period were used. Patients with a TBI were identified and both univariate and multivariate analyses were performed. RESULTS: 2274 brain-injured patients including 1794 males (78.9%) were identified. The mean age of the patients was 30.1 ± 19.11 years. The age of 345 patients was less than 12, while 137 patients were older than 65. 383 patients (16.9%) died as a result of their injury. Univariate analysis showed a significant association between mortality and the following factors: age, sex, Glasgow Coma Scale (GCS), Injury Severity Score (ISS), systolic, diastolic and mean arterial blood pressure (BP), and respiratory rate (RR) (p<0.05).The logistic regression analysis revealed a statistically significant association between death and age (odds ratio [OR]=1.04), GCS (OR=0.59), ISS (OR=1.03), mean arterial BP (OR=0.71), and RR (OR=0.82) one-half hour after hospital arrival. CONCLUSION: Our results demonstrated that age, GCS, ISS, BP, and RR as prognostic factors in patients with TBI indicate those that need special care during the initial management in the emergency department.

Strengthening injury surveillance system in iran.

OBJECTIVE: To strengthen the current Injury Surveillance System (IS System) in order to better monitor injury conditions, improve protection ways and promote safety. METHODS: At first we carried out a study to evaluate the frameworks of IS System in the developed countries. Then all the available documents from World Health Organization, Eastern Mediterranean Regional Organization, as well as Minister of Health and Medical Education concerning Iran were reviewed. Later a national stakeholder's consultation was held to collect opinions and views. A national workshop was also intended for provincial representatives from 41 universities to identify the barriers and limitations of the existing program and further to strengthen injury surveillance. RESULTS: The evaluation of the current IS System revealed many problems, mainly presented as lack of accurate pre- and post-hospital death registry, need of precise injury data registry in outpatient medical centers, incomplete injury data registry in hospitals and lack of accuracy in definition of variables in injury registry. The five main characteristics of current IS System including flexibility, acceptability, simplicity, usefulness and timeliness were evaluated as moderate by experts. CONCLUSIONS: Major revisions must be considered in the current IS System in Iran. The following elements should be added to the questionnaire: identifier, manner of arrival to the hospital, situation of the injured patient, consumption of alcohol and opioids, other involved participants in the accident, intention, severity and site of injury, side effects of surgery and medication, as well as one month follow-up results. Data should be collected from 10% of all hospitals in Iran and analyzed every 3 months. Simultaneously data should be online to be retrieved by researches.

Non-infarct related artery microvascular obstruction is associated with worse persistent diastolic dysfunction in patients with revascularized ST elevation myocardial infarction.

BACKGROUND: Infarct-artery (IRA) microvascular obstruction (MVO) is associated with diastolic dysfunction (DD) in STEMI patients. However, association between nonIRA MVO and DD in STEMI patients remains unknown. We hypothesized that revascularized STEMI patients with IRA and nonIRA MVO (IRA + nonIRA+), compared to those without nonIRA MVO (IRA + nonIRA-), have worse DD at presentation and long-term follow-up. METHODS: 87 IRA-revascularized STEMI patients had cardiac magnetic resonance imaging (MRI) [to evaluate MVO] and TTE (to evaluate diastolic function) within 1 week of presentation. Diastolic function was re-assessed by TTE at 3.97 ± 3.24 years. Baseline and follow-up DD prevalence and grade were studied in IRA + nonIRA + vs. IRA + nonIRA- MVO patients. RESULTS: 54 (62%) patients were IRA + nonIRA+ and 33 (38%) IRA + nonIRA-at baseline. IRA + nonIRA + patients had higher DD frequency at baseline (40.7 vs. 6.1%, p = 0.006) and follow-up (50.0 vs. 13.0%, p = 0.05). Only IRA + nonIRA + patients had increase in mitral medial E/e' (20.0%, p = 0.043) and trend towards increase in mitral E/A (31.1%, p = 0.063) at follow-up. IRA + nonIRA + patients had greater left atrial volume index increase (23.7%, p = 0.032 vs. 15.5%, p = 0.029) and smaller prolongation in deceleration time (15.4%, p = 0.018 vs. 18.7%, p = 0.044) at follow-up compared to IRA + nonIRA-. Grade 1 DD increased (60.9-73.9%) and combined grades 2/3 decreased (30.4-13.0%) at follow-up in IRA + nonIRA-patients. In contrast, grade 1 DD decreased (77.8-61.1%) and combined grades 2/3 increased (8.3-22.2%) at follow-up in IRA + nonIRA + patients. CONCLUSION: Concurrent IRA and nonIRA MVO in revascularized STEMI patients is associated with higher DD prevalence and worse DD grade on long-term follow-up.

Value of urinary carbohydrate antigen 19-9 to predict failure of conservative management in children with ureteropelvic junction obstruction.

OBJECTIVE: To assess the role of urinary carbohydrate antigen 19-9 (CA19-9) measurement in determining optimal management of ureteropelvic junction obstruction (UPJO) and predicting failure of conservative management. PATIENTS AND METHODS: Children with UPJO diagnosed between December 2012 and April 2015 were included. Depending on clinical and para-clinical findings, patients were divided into three groups: Group 1 consisted of patients who were considered for non-operative management with improvement of the condition during the course of follow-up. Group 2 were suitable for observation; however due to deterioration of condition pyeloplasty was indicated after a period of observation. Group 3 patients required immediate pyeloplasty. Urinary CA19-9 was measured in all patients at baseline and compared between the study groups. RESULTS: A total of 112 children (115 affected kidneys) with UPJO and mean age of 18.6 ±â€¯3.3 months were assessed. Group 1, 2, and 3 consisted of 54(48.2%), 24(21.4%), and 34(30.4%) patients, respectively. Mean baseline urinary CA19-9 was 37.83 ±â€¯5.20, 145.45 ±â€¯18.38 and 244.62 ±â€¯41.42 in groups 1, 2 and 3, respectively. Multivariate analysis showed that both CA19-9 and APD are independent predictors of need for surgery in patients on observation. ROC curve analysis revealed that urinary CA19-9 level at cut off value of 52.6 U/mL had sensitivity of 92.0% and specificity of 70.9% in predicting failure of non-operative management. CONCLUSION: Higher urinary CA19-9 level is associated with failure of non-operative management in patients with UPJO. Such patients may require close follow-up and assessments to prevent irreversible damage to the kidney. TYPE OF STUDY: Study of Diagnostic Test. LEVEL OF EVIDENCE: Level II.

Evaluating the efficacy of tissue-engineered human amniotic membrane in the treatment of myocardial infarction.

AIM: The aim of this study was to evaluate the efficacy of tissue-engineered amniotic membrane (AM) in the treatment of myocardial infarction lesions. MATERIALS & METHODS: 20 rats were subjected to coronary arterial ligation in order to induce myocardial infarction injury. Decellularized human AMs were seeded with 2 × 105 adipose-derived mesenchymal stem cells and were implanted in the infarcted hearts. RESULTS & CONCLUSION: Histological and immunohistochemical evaluations indicated the regeneration of cardiomyocytes and reduction of inflammation and fibrosis in the patch-implanted group compared with a control group, 14 days after the surgery. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labeling assay was suggestive for apoptosis reduction in the patch-implanted specimens. This study suggested that human AM can be developed into a novel treatment for treating postmyocardial infarction.

In Vivo Response of Acellular Porcine Pericardial for Tissue Engineered Transcatheter Aortic Valves.

Current heart valve prostheses have limitations that include durability, inability to grow in pediatric patients, and lifelong anticoagulation. Transcatheter aortic valve replacements are minimally invasive procedures, and therefore have emerged as an alternative to traditional valve prostheses. In this experiment, the regenerative capacity of potential tissue engineered transcatheter valve scaffolds (1) acellular porcine pericardium and (2) mesenchymal stem cell-seeded acellular porcine pericardium were compared to native porcine aortic valve cusps in a rat subcutaneous model for up to 8 weeks. Immunohistochemistry, extracellular matrix evaluation, and tissue biomechanics were evaluated on the explanted tissue. Acellular valve scaffolds expressed CD163, CD31, alpha smooth muscle actin, and vimentin at each time point indicating host cell recellularization; however, MSC-seeded tissue showed greater recellularization. Inflammatory cells were observed with CD3 biomarker in native porcine pericardial tissue throughout the study. No inflammation was observed in either acellular or MSC-seeded scaffolds. There was no mechanical advantage observed in MSC-seeded tissue; however after the first week post-explant, there was a decrease in mechanical properties in all groups (p < 0.05). MSC-seeded and acellular porcine pericardium expressed decreased inflammatory response and better host-cell recellularization compared to the native porcine aortic valve cusps.

Preparation and characterization of human size whole heart for organ engineering: scaffold microangiographic imaging.

Definitive treatment for end-stage heart failure is heart transplantation, however, this is associated with several limitations. Aim: We decellularized and assessed ovine hearts through coronary perfusion. To evaluate in situ recellularization, a decellular graft was transplanted hetrotopically into the omental wrap. Results: Cell removal was confirmed by DNA count (11.68 ± 3.42 ng/mg dry weight). Elastic, reticular and collagen fiber were well preserved. There was a slight change in both glycosaminoglycan (7.01 ± 1.36 to 8.37 ± 0.32 µg/mg) and collagen (32.37 ± 2.3 to 36.31 ± 2.1) µg/mg (p > 0.05). Angiography and blood circulation revealed an intact vascular network. Implantation led to proper vascularization. Image J indicated CD31: 23.98 ± 12.3; CD34: 48.67 ± 19.5 and αSMA: 78.33 ± 27.8 inch/cm. Conclusion: Bio-scaffold of human size heart is achievable for future steps employing this technique.

Three-year efficacy and patency follow-up of decellularized human internal mammary artery as a novel vascular graft in animal models.

BACKGROUND: Various investigations have reported that the internal mammary artery (IMA) is an efficient and functional choice of conduit for vascular graft surgeries, especially for coronary artery bypass grafts; however, the quest to find an ideal vascular substitute remains. We hypothesized that acellular IMA could be an appropriate graft for small-diameter vascular bypasses that could be used in various surgeries including coronary artery bypass grafting. METHODS: We decellularized human IMAs and performed histologic evaluations and scanning electron microscopy to confirm the decellularization process and the preservation of the extracellular matrix. Subsequently, we grafted the scaffolds into the superficial femoral arteries of 8 New Zealand rabbits with an end-to-end anastomosis. Computed tomography angiograms were provided at 3, 12, and 36 months postoperatively. Subsequently, the animals were killed, and biopsies were taken for histologic and immunohistochemical assessments. RESULTS: Evaluation of the acellular tissue confirmed the efficacy of the decellularization protocol and the preservation of the extracellular matrix. All 8 animals survived the entire follow-up period. Doppler ultrasonography and computed tomography angiographies verified the conduit's patency. Histologic assessments depicted the recellularization of all 3 layers of the scaffold. Smooth muscle cells were detected in tunica media. Immunohistochemical assessments confirmed these findings. CONCLUSIONS: In conclusion, we demonstrated that acellular human IMA could be used as an efficient small-diameter vascular substitute with high patency. These findings could pave the path for future investigations on the clinical application of acellular IMA as a novel vascular graft for small-diameter bypass surgeries.

Whole organ sheep kidney tissue engineering and in vivo transplantation: Effects of perfusion-based decellularization on vascular integrity.

INTRODUCTION: During the past decade, increased efforts have been made to develop alternative management options instead of dialysis and homograft renal transplantation for end-stage renal disease. State-of-the-art methods employ tissue engineering to produce natural acellular scaffolds that could resolve the concern of allograft rejection and obviate the need for immunosuppressive therapy. Complete decellularization of kidney with intact extracellular matrix is crucial for in vivo compatibility and success of transplantation. Herein, we evaluate the efficacy of two different whole organ decellularization protocols, vasculature integrity, and in vivo transplantation of sheep kidneys. MATERIALS AND METHODS: Eight sheep kidneys were decellularized by perfusion-based method utilizing two different protocols (Protocol 1: 1% Triton X-100 and 0.5% SDS vs. Protocol 2: 1% SDS). The samples were evaluated by histopathology in terms of decellularization and extracellular matrix preservation. Computerized tomography angiography was performed to evaluate vasculature. Subsequently, both methods were transplanted in four sheep and monitored for vascular integrity and extravasations in short-term. RESULTS: Scaffolds obtained from both protocols were entirely decellularized. However; the extracellular matrix was better preserved in protocol 1 compared to protocol 2. In addition, the vascular integrity was intact in decellularized scaffolds treated with Triton X-100 plus SDS (protocol 1). After transplantation, the samples treated with protocol 2 showed extravasation of fluid in the interstitial space while the samples treated with protocol 1 showed intact extracellular matrix and vasculature. CONCLUSIONS: This study demonstrated the efficacy of well-preserved acellular scaffold and vasculature network in post renal transplant outcome in a sheep model. These results have potential to pave the road for further investigations in acellular whole organ transplantation.

Microsurgical anastomosis of renal vasculature in rats: A practical platform for acellular kidney transplantation.

End-stage renal disease is becoming a contemporary global concern with increasing prevalence. The available treatment strategies are limited to dialysis and renal transplantation. However, limited organ supply and autoimmune rejection are the shortcomings that limit widespread application of transplantation. Favorably, regenerative medicine is able to provide acellular natural scaffolds for renal transplantation. Experimental surgeries in animal models are a fundamental step in transplantation research. This video presents a practical method for transplantation of bilateral acellular kidneys in a rat model, which could serve as a key step for further research.