Transforming native exosomes to engineered drug vehicles: A smart solution to modern cancer theranostics.

Exosomes have been the hidden treasure of the cell in terms of cellular interactions, transportation and therapy. The native exosomes (NEx) secreted by the parent cells hold promising aspects in cancer diagnosis and therapy. NEx has low immunogenicity, high biocompatibility, low toxicity and high stability which enables them to be an ideal prognostic biomarker in cancer diagnosis. However, due to heterogeneity, NEx lacks specificity and accuracy to be used as therapeutic drug delivery vehicle in cancer therapy. Transforming these NEx with their innate structure and multiple receptors to engineered exosomes (EEx) can provide better opportunities in the field of cancer theranostics. The surface of the NEx exhibits numeric receptors which can be modified to pave the direction of its therapeutic drug delivery in cancer therapy. Through surface membrane, EEx can be modified with increased drug loading potentiality and higher target specificity to act as a therapeutic nanocarrier for drug delivery. This review provides insights into promising aspects of NEx as a prognostic biomarker and drug delivery tool along with its need for the transformation to EEx in cancer theranostics. We have also highlighted different methods associated with NEx transformations, their nano-bio interaction with recipient cells and major challenges of EEx for clinical application in cancer theranostics.

Biocompatible Human Placental Extracellular Matrix Derived Hydrogels.

Solubilizing extracellular matrix (ECM) materials and transforming them into hydrogels has expanded their potential applications both in vitro and in vivo. In this study, hydrogels are prepared by decellularization of human placental tissue using detergent and enzymes and by the subsequent creation of a homogenized acellular placental tissue powder (P-ECM). A perfusion-based decellularization approach is employed using detergent and enzymes. The P-ECM with and without gamma irradiation is then utilized to prepare P-ECM hydrogels. Physical and biological evaluations are conducted to assess the suitability of the P-ECM hydrogels for biocompatibility. The decellularized tissue has significantly reduced cellular content and retains the major ECM proteins. Increasing the concentration of P-ECM leads to improved mechanical properties of the P-ECM hydrogels. The biocompatibility of the P-ECM hydrogel is demonstrated through cell proliferation and viability assays. Notably, gamma-sterilized P-ECM does not support the formation of a stable hydrogel. Nonetheless, the use of HCl during the digestion process effectively decreases spore growth and bacterial bioburden. The study demonstrates that P-ECM hydrogels exhibit physical and biological attributes conducive to soft tissue reconstruction. These hydrogels establish a favorable microenvironment for cell growth and the need for investigating innovative sterilization methods.

Scalable production of tissue-like vascularized liver organoids from human PSCs.

The lack of physiological parity between 2D cell culture and in vivo culture has led to the development of more organotypic models, such as organoids. Organoid models have been developed for a number of tissues, including the liver. Current organoid protocols are characterized by a reliance on extracellular matrices (ECMs), patterning in 2D culture, costly growth factors and a lack of cellular diversity, structure, and organization. Current hepatic organoid models are generally simplistic and composed of hepatocytes or cholangiocytes, rendering them less physiologically relevant compared to native tissue. We have developed an approach that does not require 2D patterning, is ECM independent, and employs small molecules to mimic embryonic liver development that produces large quantities of liver-like organoids. Using single-cell RNA sequencing and immunofluorescence, we demonstrate a liver-like cellular repertoire, a higher order cellular complexity, presenting with vascular luminal structures, and a population of resident macrophages: Kupffer cells. The organoids exhibit key liver functions, including drug metabolism, serum protein production, urea synthesis and coagulation factor production, with preserved post-translational modifications such as N-glycosylation and functionality. The organoids can be transplanted and maintained long term in mice producing human albumin. The organoids exhibit a complex cellular repertoire reflective of the organ and have de novo vascularization and liver-like function. These characteristics are a prerequisite for many applications from cellular therapy, tissue engineering, drug toxicity assessment, and disease modeling to basic developmental biology.

Identification of critical autophagy-related proteins in diabetic retinopathy: A multi-dimensional computational study.

Diabetic retinopathy (DR) is a common consequence of diabetes mellitus and a primary cause of visual impairment in middle-aged and elderly individuals. DR is susceptible to cellular degradation facilitated by autophagy. In this study, we have employed a multi-layer relatedness (MLR) approach to uncover novel autophagy-related proteins involved in DR. The objective of MLR is to determine the relatedness of autophagic and DR proteins by incorporating both expression and prior-knowledge-based similarities. We constructed a prior knowledge-based network and identified the topologically significant novel disease-related candidate autophagic proteins (CAPs). Then, we evaluated their significance in a gene co-expression and a differentially-expressed gene (DEG) network. Finally, we investigated the proximity of CAPs to the known disease-related proteins. Leveraging this methodology, we identified three crucial autophagy-related proteins, TP53, HSAP90AA1, and PIK3R1, which can influence the DR interactome in various layers of heterogeneity of clinical manifestations. They are strongly related to multiple detrimental characteristics of DR, such as pericyte loss, angiogenesis, apoptosis, and endothelial cell migration, and hence may be used to prevent or delay the progression and development of DR. We evaluated one of the identified targets, TP53, in a cell-based model and found that its inhibition resulted in reduced angiogenesis in high glucose condition required to control DR.

Fabrication of a Chitosan-Based Wound Dressing Patch for Enhanced Antimicrobial, Hemostatic, and Wound Healing Application.

Wounds are a serious life threat that occurs in daily life. The complex cascade of synchronized cellular and molecular phases in wound healing is impaired by different means, involving infection, neuropathic complexes, abnormal blood circulation, and cell proliferation at the wound region. Thus, to overcome these problems, a multifunctional wound dressing material is fabricated. In the current research work, we have fabricated a wound dressing polymeric patch, with poly(vinyl alcohol) (PVA) and chitosan (Cs) incorporated with a photocatalytic graphene nanocomposite (GO/TiO2(V-N)) and curcumin by a gel casting method, that focuses on multiple stages of the healing process. The morphology, swelling, degradation, moisture vapor transmission rate (MVTR), porosity, light-induced antibacterial activity, hemolysis, blood clotting, blood abortion, light-induced biocompatibility, migration assay, and drug release were analyzed for the polymeric patches under in vitro conditions. PVA/Cs/GO/TiO2(V-N)/Cur patches have shown enhanced wound healing in in vivo wound healing experiments on Wister rats. They show higher collagen deposition, thicker granulation tissue, and higher fibroblast density than conventional dressing. A histological study shows excellent re-epithelialization ability and dense collagen deposition. In vitro and in vivo analysis confirmed that PVA/Cs/GO/TiO2(V-N) and PVA/Cs/GO/TiO2(V-N)/Cur patches enhance the wound healing process.

A paper microfluidic device based colorimetric sensor for the detection and discrimination of elapid versus viper envenomation.

Snake bites are a neglected tropical disease, causing mortality and severe damage to various vital organs like the nervous system, kidneys and heart. There is increasing interest in designing new antivenom treatments that are more specific to particular groups (either taxonomic or regional) of species, given the increasing evidence that current polyvalent Indian antivenom is ineffective in many situations. Under these circumstances, being able to detect the species, or a group of species, responsible for the envenomation becomes important. Unfortunately, no such diagnostic tool is available in the Indian market. Such a tool will need to be rapid, sensitive and affordable. To address this need, we have combined the power of nanotechnology and paper microfluidics and herein report a device that has the ability to detect and differentiate viper venom from elapid and scorpion venom. In principle, this assay is based on the release of the dye from the stimuli-responsive glutaraldehyde cross-linked methylene blue-loaded gelatin (GMG) nanoparticles in the presence of snake venom metalloproteases and serine proteases. The developed equipment-free assay can detect and discriminate viper venom from that of elapids and scorpions. The low-end detection limit of the sensor is ∼3.0 ng for the saw-scaled viper Echis carinatus, while the same for Russell's viper Daboia russelii is ∼6.0 ng. The performance of the sensor remains unaltered for different batches of GMG nanoparticles. Altogether, this finding establishes the role of nanotechnology and paper microfluidics in the rapid and accurate detection of viper venom.

Development of chitosan/poly (vinyl alcohol)/graphene oxide loaded with vanadium doped titanium dioxide patch for visible light driven antibacterial activity and accelerated wound healing application.

Wound healing is a multi-stage process that is dynamic, interactive, and complicated. However, many nanomaterials are employed to expedite wound healing by demonstrating antibacterial activity or boosting cell proliferation. But only one phase is focused during the wound healing process. As a result, there is a need for optimum wound dressing materials that promotes different wound healing cascades with ideal properties. Herein, Graphene Oxide loaded with vanadium (V) doped titanium dioxide (TiO2) blended with chitosan, and polyvinyl alcohol (CS/PVA/GO/TiO2-V) patch was developed for wound healing. XRD, FTIR and FE-SEM analyses were carried out to study the morphology and structural property of the patch. The fabricated patch has a high surface porosity, excellent moisture vapor transfer rate, appropriate swelling behaviour, and oxygen permeability, which results in an excellent moist environment for wound breathing and effective management of wound exudates. The antibacterial test showed significant antibacterial efficacy against wound infections in the presence of light when compared to dark. In-vitro analysis such as hemocompatibility, cytotoxicity, cell adhesion, and scratch assay show the predicted potential wound healing application with high biocompatibility. These results suggest that CS/PVA/GO/TiO2-V patch provides a microenvironment favourable to cells' growth and differentiation and positively modulates full-thickness wounds' healing.

Recent Advances in Cardiac Tissue Engineering for the Management of Myocardium Infarction.

Myocardium Infarction (MI) is one of the foremost cardiovascular diseases (CVDs) causing death worldwide, and its case numbers are expected to continuously increase in the coming years. Pharmacological interventions have not been at the forefront in ameliorating MI-related morbidity and mortality. Stem cell-based tissue engineering approaches have been extensively explored for their regenerative potential in the infarcted myocardium. Recent studies on microfluidic devices employing stem cells under laboratory set-up have revealed meticulous events pertaining to the pathophysiology of MI occurring at the infarcted site. This discovery also underpins the appropriate conditions in the niche for differentiating stem cells into mature cardiomyocyte-like cells and leads to engineering of the scaffold via mimicking of native cardiac physiological conditions. However, the mode of stem cell-loaded engineered scaffolds delivered to the site of infarction is still a challenging mission, and yet to be translated to the clinical setting. In this review, we have elucidated the various strategies developed using a hydrogel-based system both as encapsulated stem cells and as biocompatible patches loaded with cells and applied at the site of infarction.

A critical appraisal of humanized alternatives to fetal bovine serum for clinical applications of umbilical cord derived mesenchymal stromal cells.

OBJECTIVE: The study is aimed to verify the possibility of using humanized alternatives to fetal bovine serum (FBS) such as umbilical cord blood plasma (CBP) and AB+ plasma to support the long-term growth of mesenchymal stromal cells (MSCs) derived from the umbilical cord. We hypothesized that umbilical CBP would be a potential substitute to FBS, especially for small scale autologous clinical transplantations. METHODS: The MSCs were cultured for six consecutive passages to evaluate xeno-free media's ability to support long-term growth. Cell proliferation rates, colony-forming-unit (CFU) efficiency and population doublings of expanded MSCs, were investigated. Ex vivo expanded MSCs were further characterized using flow cytometry and quantitative PCR. The impact of cryopreservation and composition of cryomedium on phenotype, viability of MSC was also assessed. RESULTS: Our results on cell proliferation, colony-forming unit efficiency suggested that the expansion of the cells was successfully carried out in media supplemented with humanized alternatives. MSCs showed lower CFU counts in FBS (~ 25) than humanized alternatives (~ 35). The gene expression analysis revealed that transcripts showed significant differential expression by two to three folds in the FBS group compared with MSCs grown in medium with humanized alternatives (p < 0.05). In addition, MSCs grown in a medium with FBS had more osteogenic activity, a signature of unwanted differentiation. The majority of ex vivo expanded MSCs at early and late passages expressed CD44+, CD73+, CD105+, CD90+, and CD166+ in all the experimental groups tested (~ 90%). In contrast to the other MSC surface markers, expression levels of STRO-1+ (~ 21-10%) and TNAP+ (~ 29-11%) decreased with the increase in passage number for MSCs cultured in a FBS-supplemented medium (p < 0.05). CONCLUSION: Our results established that CBP supported culture of umbilical cord tissue-derived MSCs and is a safer Xeno free replacement to FBS. The use of CBP also enables the storage of umbilical cord tissue derived MSCs in patient-specific conditions to minimize adverse events if cells are delivered directly to the patient.

Oncoplastic Breast Reconstruction in Breast Conservation Surgery: Improving the Oncological and Aesthetic Outcomes.

Breast conservation surgery (BCS) is now the standard of care for patients with early breast cancer. The main contraindications for BCS besides the presence of multicentricity and diffuse microcalcifications are inadequate tumour size to breast size ratio. With the advent of oncoplastic techniques, the indications of BCS may be further extended to patient with larger tumour size and or small volume breast. We prospectively assessed 42 patients undergoing oncoplastic breast conservation surgery for cosmetic and oncologic outcomes. Cosmetic outcome assessment was done by comparison of operated breast to contralateral breast by an independent surgeon, nurse and patient's attendant at 6 months post-surgery. Risk factors for compromised oncologic outcomes included grades II/III tumours and non-ductal histology. Intraoperative margin assessment with frozen section analysis proved to be important in order to achieve negative surgical margins on final histopathology. By univariate analysis, tumours located in central quadrant and medial half of the breast had similar cosmetic outcomes comparable to tumours located in other quadrants. Majority of our patients (90%) had overall good to excellent cosmetic outcomes on Harvard scale. Oncoplastic breast conservation surgery techniques allow for larger parenchymal resections without compromising oncologic and cosmetic results. It further allows extension of BCS to patients otherwise denied for the same based on earlier recommendations for mastectomy. Oncoplastic techniques and intraoperative margin assessment with frozen section are vital in attaining adequate margins and also decrease chance of local recurrence and revision surgery for positive margins.

Cellular growth and tube formation of HTR8/SVneo trophoblast: effects of exogenously added fatty acid-binding protein-4 and its inhibitor.

Adequate placental angiogenesis is critical for the establishment of the placental circulation and thus for normal feto-placental growth and development. Fatty acid-binding protein-4 (FABP4) plays a pro-angiogenic role in endothelial cells; however, very little information is available in placental first trimester trophoblast cells. Here we report that exogenously added FABP4 (exo-FABP4) stimulated tube formation (as a measure of in vitro angiogenesis) in HTR8/SVneo trophoblastic cells. HTR-8/SVneo cells were incubated in the presence of exogenously added FABP4 at different concentrations and time points. Cellular growth, proliferation, in vitro tube formation, expression of growth stimulatory-, fatty acid transporters, and angiogenic genes were investigated. Internalization of exo-FABP4 was carried out using immunocytochemistry. Radioactive fatty acid uptake was determined in the presence and absence of FABP4 metabolic inhibitor. Exo-FABP4 (10-100 ng/ml) stimulated proliferation of HTR8/SVneo cells as compared to control. Exo-FABP4 dose dependently increased growth and viability of the cells to the similar extent as done by 50 µM of arachidonic acid. Exo-FABP4-induced tube formation and proliferation were significantly inhibited by FABP4 (BMS309403) inhibitor. Exo-FABP4 stimulated the expression of growth stimulatory genes such as tissue inhibitor of matrix metalloproteinases-1 (TIMP1), insulin-like growth factor 1 (IGF1), and also prokineticin 2 (PROK2), the pro-angiogenic mediators in these cells. In addition, expressions of genes associated with proliferation and differentiation such as sonic hedgehog (SHH) and WNT1 inducible signalling pathway protein 1 (WISP1) were significantly expressed when cells were exposed to exo-FABP4. Our findings reveal a pro-angiogenic role of FABP4 in first trimester placental trophoblast cells and its regulation may have impact in placental physiology.

Development of a rapid screen for the endodermal differentiation potential of human pluripotent stem cell lines.

A challenge facing the human pluripotent stem cell (hPSC) field is the variability observed in differentiation potential of hPSCs. Variability can lead to time consuming and costly optimisation to yield the cell type of interest. This is especially relevant for the differentiation of hPSCs towards the endodermal lineages. Endodermal cells have the potential to yield promising new knowledge and therapies for diseases affecting multiple organ systems, including lung, thymus, intestine, pancreas and liver, as well as applications in regenerative medicine and toxicology. Providing a means to rapidly, cheaply and efficiently assess the differentiation potential of multiple hPSCs is of great interest. To this end, we have developed a rapid small molecule based screen to assess the endodermal potential (EP) of hPSCs, based solely on definitive endoderm (DE) morphology. This drastically reduces the cost and time to identify lines suitable for use in deriving endodermal lineages. We demonstrate the efficacy of this screen using 10 different hPSCs, including 4 human embryonic stem cell lines (hESCs) and 6 human induced pluripotent stem cell lines (hiPSCs). The screen clearly revealed lines amenable to endodermal differentiation, and only lines that passed our morphological assessment were capable of further differentiation to hepatocyte like cells (HLCs).

Small-Molecule-Directed Hepatocyte-Like Cell Differentiation of Human Pluripotent Stem Cells.

Hepatocyte-like cells (HLCs) generated in vitro from human pluripotent stem cells (hPSCs) provide an invaluable resource for basic research, regenerative medicine, drug screening, toxicology, and modeling of liver disease and development. This unit describes a small-molecule-driven protocol for in vitro differentiation of hPSCs into HLCs without the use of growth factors. hPSCs are coaxed through a developmentally relevant route via the primitive streak to definitive endoderm (DE) using the small molecule CHIR99021 (a Wnt agonist), replacing the conventional growth factors Wnt3A and activin A. The small-molecule-derived DE is then differentiated to hepatoblast-like cells in the presence of dimethyl sulfoxide. The resulting hepatoblasts are then differentiated to HLCs with N-hexanoic-Tyr, Ile-6 aminohexanoic amide (Dihexa, a hepatocyte growth factor agonist) and dexamethasone. The protocol provides an efficient and reproducible procedure for differentiation of hPSCs into HLCs utilizing small molecules. © 2016 by John Wiley & Sons, Inc.

A Patient-Inspired Ex Vivo Liver Tissue Engineering Approach with Autologous Mesenchymal Stem Cells and Hepatogenic Serum.

Design and development of ex vivo bioengineered liver tissue substitutes intended for subsequent in vivo implantation has been considered therapeutically relevant to treat many liver diseases that require whole-organ replacement on a long-term basis. The present study focus on patient-inspired ex vivo liver tissue engineering strategy to generate hepatocyte-scaffold composite by combining bone marrow mesenchymal stem cells (BMSCs) derived from cardiac failure patients with secondary hyperbilirubinemia as primers of hepatic differentiation and hepatocyte growth factor (HGF)-enriched sera from same individuals as hepatic inducer. A biodegradable and implantable electrospun fibrous mesh of poly-l-lactic acid (PLLA) and gelatin is used as supporting matrix (average fiber diameter = 285 ± 64 nm, porosity = 81 ± 4%, and average pore size = 1.65 ± 0.77 µm). The fibrous mesh supports adhesion, proliferation, and hepatic commitment of patient-derived BMSCs of adequate stemness using HGF-enriched sera generating metabolically competent hepatocyte-like cells, which is comparable to the hepatic induction with defined recombinant growth factor cocktail. The observed results confirm the combinatorial effects of nanofiber topography and biochemical cues in guiding hepatic specification of BMSCs. The fibrous mesh-hepatocyte construct developed in this study using natural growth factors and BMSCs of same individual is promising for future therapeutic applications in treating damaged livers.

Nanofibers coated on acellular tissue-engineered bovine pericardium supports differentiation of mesenchymal stem cells into endothelial cells for tissue engineering.

AIM: This study aimed to develop biodegradable, polymer-based nanofibers coated on acellular tissue-engineered bovine pericardium (ATEBP) for cell interfaces, enabling more exquisite functionality, such as mesenchymal stem cell (MSC) adhesion, proliferation and differentiation into endothelial cells for tissue engineering. MATERIALS & METHODS: ATEBP coated with nanofibers of poly(L-lactic acid)-co-poly(ε-caprolactone) (PLACL) and a blend of PLACL and gelatin were analyzed for human bone marrow-derived MSC adhesion, proliferation and differentiation into endothelial cells. RESULTS: The cell culture-based approach showed an increase in human bone marrow-derived MSC adhesion, proliferation and differentiation into endothelial cells on ATEBP coated with PLACL/gelatin nanofibers compared with ATEBP and PLACL nanofibers coated on ATEBP. CONCLUSION: ATEBP coated with PLACL/gelatin nanofibrous scaffolds, along with human bone marrow-derived MSCs differentiated into endothelial cells, might improve the scaffolds' functionality for tissue engineering.

Nanofiber-reinforced myocardial tissue-construct as ventricular assist device.

OBJECTIVES: This study aimed to create a myocardial tissue construct by tissue engineering to repair, replace, and regenerate damaged cardiac tissue. METHODS AND RESULTS: Human cardiac muscles harvested from a homograft heart retrieval system were decellularized followed by coating with electrospun nanofibers to make them amenable to scaffolding. These processed cardiac tissues were nourished in modified media having ischemic cardiac tissue conditioned media in 6 separate experimental variants, and cord blood mononuclear cells were injected into 4 of them. On the 17th day of culture, the nanofiber-coated scaffolds injected with mononuclear cells and/or reinforced by electrical and mechanical forces, started contracting spontaneously at varying rates, while the control remain noncontractile. Histological staining confirmed the pre-culture acellularity as well as post-culture stem cell viability, and revealed expression of troponin I and cardiac myosin. The acellular processed scaffold when implanted into sheep ischemic myocardial apex revealed transformation into sheep myocardium after 4 months of implantation. CONCLUSION: These results provide direct evidence for the re-cellularization of decellularized cardiac tissue grafts reinforced with a polymer nanofiber coating, by human mononuclear cells injection, leading to generation of a tissue-engineered myocardial construct.

In vitro hepatic trans-differentiation of human mesenchymal stem cells using sera from congestive/ischemic liver during cardiac failure.

Cellular therapy for end-stage liver failures using human mesenchymal stem cells (hMSCs)-derived hepatocytes is a potential alternative to liver transplantation. Hepatic trans-differentiation of hMSCs is routinely accomplished by induction with commercially available recombinant growth factors, which is of limited clinical applications. In the present study, we have evaluated the potential of sera from cardiac-failure-associated congestive/ischemic liver patients for hepatic trans-differentiation of hMSCs. Results from such experiments were confirmed through morphological changes and expression of hepatocyte-specific markers at molecular and cellular level. Furthermore, the process of mesenchymal-to-epithelial transition during hepatic trans-differentiation of hMSCs was confirmed by elevated expression of E-Cadherin and down-regulation of Snail. The functionality of hMSCs-derived hepatocytes was validated by various liver function tests such as albumin synthesis, urea release, glycogen accumulation and presence of a drug inducible cytochrome P450 system. Based on these findings, we conclude that sera from congestive/ischemic liver during cardiac failure support a liver specific microenvironment for effective hepatic trans-differentiation of hMSCs in vitro.

Biomimetic acellular detoxified glutaraldehyde cross-linked bovine pericardium for tissue engineering.

Glutaraldehyde (GLUT) processing, cellular antigens, calcium ions in circulation, and phospholipids present in the native tissue are predominantly responsible for calcification, degeneration, and lack of natural microenvironment for host progenitor cell migration in tissue implants. The study presents an improved methodology for adhesion and proliferation of endothelial progenitor cells (EPCs) without significant changes in biomechanical and biodegradation properties of the processed acellular bovine pericardium. The anti-calcification potential of the processed tissue was enhanced by detoxification of GLUT-cross-linked bovine pericardium by decellularization, pretreating it with ethanol or removing the free aldehydes by citric acid treatment and lyophilization. The treated tissues were assessed for biomechanical properties, GLUT ligand quantification, adhesion, proliferation of EPCs, and biodegradability. The results indicate that there was no significant change in biomechanical properties and biodegradability when enzymatic hydrolysis (p>0.05) is employed in detoxified acellular GLUT cross-linked tissue (DBP-G-CA-ET), compared with the native detoxified GLUT cross-linked bovine pericardium (NBP-G-CA-ET). DBP-G-CA-ET exhibited a significant (p>0.05) increase in the viability of EPCs and cell adhesion as compared to acellular GLUT cross-linked bovine pericardium (p<0.05). Lyophilized acellular detoxified GLUT cross-linked bovine pericardium, employed in our study as an alternative to conventional GLUT cross-linked bovine pericardium, might provide longer durability and better biocompatibility, and reduce calcification. The developed bovine pericardium patches could be used in cardiac reconstruction and repair, arteriotomy, soft tissue repair, and general surgical procedures with tissue regeneration dimensions.

Polypropelene mesh eroding transverse colon following laparoscopic ventral hernia repair.

Polypropylene mesh when used in laparoscopic ventral hernia repair can produce the worst complication such as enterocutaneous fistula. We report an interesting case of incisional hernia operated with laparoscopic polypropylene mesh hernioplasty who subsequently developed an enterocutaneous fistula 1 month after surgery. A fistulogram showed dye entering into the transverse colon. On exploration, the culprit polypropylene mesh was found to have eroded into the mid-transverse colon causing the fistula. Resection and end-to-end anastomosis of the colon were done with the removal of the mesh. On literature review, polypropylene mesh erosion in to transverse colon is rare.

Crosslinked acellular saphenous vein for small-diameter vascular graft.

OBJECTIVE: Patients with congenital and acquired heart diseases or arteriopathy require small-diameter vascular grafts for arterial reconstruction. Autologous veins are the most suitable graft, but when absent, an alternative is necessary. This work addresses the issue. BACKGROUND: Tissue-engineering efforts to create such grafts by modifications of acellular natural scaffolds are considered a promising area. METHODS: Homologous saphenous veins harvested from cadavers and organ donors were processed by decellularization with detergent and enzymatic digestion, followed by crosslinking by dye-mediated photooxidation. They were validated for acellularity, mechanical strength, and crosslink stability. In-vitro and in-vivo cytotoxicity and hemocompatibility studies were conducted. Collagen conformity was studied by Fourier transform infrared spectroscopy, and heat stability by differential scanning calorimetry. A limited large animal study was performed. RESULTS: The processing method delivered biocompatible, hemocompatible, effectively crosslinked grafts, with high heat stability of 126 , an enthalpy value of 183.5 J·g(-1), and collagen conformity close to that of the native vein. The mechanical strength was 250% better than the native vein. The presence of extracellular matrix proteins allowed the acellular vein to become a triple-layered vascular structure in the sheep venous system. CONCLUSION: Crosslinking after decellularization by the dye-mediated photooxidation method could be reproduced in any human vein to obtain a small-diameter vascular grafts.