Tissue reaction to three different types of tissue glues in an experimental aorta dissection model: a quantitative approach

Photo-Cross-Linkable, Injectable, and Highly Adhesive GelMA-Glycol Chitosan Hydrogels for Cartilage Repair

Hydrogels provide a promising platform for cartilage repair and regeneration. Although hydrogels have shown some efficacy, they still have shortcomings including poor mechanical properties and suboptimal integration with surrounding cartilage. Herein, hydrogels that are injectable, cytocompatible, mechanically robust, and highly adhesive to cartilage are developed. This approach uses GelMA-glycol chitosan (GelMA-GC) that is crosslinkable with visible light and photoinitiators (lithium acylphosphinate and tris (2,2'-bipyridyl) dichlororuthenium (II) hexahydrate ([RuII(bpy)3 ]2+ and sodium persulfate (Ru/SPS)). Ru/SPS-cross-linked hydrogels have higher compressive and tensile modulus, and most prominently higher adhesive strength with cartilage, which also depends on inclusion of GC. Tensile and push-out tests of the Ru/SPS-cross-linked GelMA-GC hydrogels demonstrate adhesive strength of ≈100 and 46 kPa, respectively. Hydrogel precursor solutions behave in a Newtonian manner and are injectable. After injection in focal bovine cartilage defects and in situ cross-linking, this hydrogel system remains intact and integrated with cartilage following joint manipulation ex vivo. Cells remain viable (>85%) in the hydrogel system and further show tissue regeneration potential after three weeks of in vitro culture. These preliminary results provide further motivation for future research on bioadhesive hydrogels for cartilage repair and regeneration.

How to test adhesive strength: a biomechanical testing for aortic glue used in type a dissection repair

OBJECTIVES

The aim of this study was to develop a method to quantify the peel force in an in vitro model simulating repair of ascending aortic dissections with tissue glue (Bioglue).

METHODS

This study adapted an adhesive T-Peel test for the determination of the peel strength of adhesives by measuring the peeling force of a T-shaped bonded tissue. Measurements were performed on iatrogenic dissected ascending porcine aorta, which has been repaired with Bioglue using different pressure levels. Four conditions were tested: zero sample pressure according to the manufacturer's recommendation (n = 10), low (504 Pa; n = 11), moderate pressure (1711 Pa; n = 24) and pressure applied by a round shaped vascular 'Borst clamp' (1764 Pa; n = 23). Non-parametric one-way analysis of variance was applied for statistical significance.

RESULTS

The median peel force (lower quartile, upper quartile) of aortic samples increased depending on the applied pressure: [no pressure 0.030 N/mm (0.016, 0.057), low pressure 0.040 N/mm (0.032, 0.070) and moderate pressure 0.214 N/mm (0.050, 0.304)]. Samples pressurized with the Borst clamp reached 0.078 N/mm (0.046, 0.152), which was comparable to the peel force of the unpeeled controls [0.107 N/mm (0.087, 0.124)]. Compared to samples without pressure, Bioglue with the application of the Borst clamp (P = 0.021) and with moderate pressure (P = 0.0007) performed significantly better.

CONCLUSIONS

The novel T-Peel test offers an attractive method to test tissue glues in defined in vitro environments. Bioglue peel force increased with pressure on the aortic sample in contrast to low or no pressure as per the manufacturer's recommendation. Modifying current recommended use may aid in increasing effectiveness of this approach.

MUC13-miRNA-4647 axis in colorectal cancer: Prospects to identifications of risk factors and clinical outcomes

MUC13, a transmembrane mucin glycoprotein, is overexpressed in colorectal cancer (CRC), however, its regulation and functions are not fully understood. It has been shown that MUC13 protects colonic epithelial cells from apoptosis. Therefore, studying MUC13 and MUC13-regulated pathways may reveal promising therapeutic approaches for CRC treatment. Growing evidence suggests that microRNAs (miRs) are involved in the development and progression of CRC. In the present study, the MUC13-miR-4647 axis was addressed in association with survival of patients. miR-4647 is predicted in silico to bind to the MUC13 gene and was analyzed by RT-qPCR in 187 tumors and their adjacent non-malignant mucosa of patients with CRC. The impact of previously mentioned genes on survival and migration abilities of cancer cells was validated in vitro. Significantly upregulated MUC13 (P=0.02) in was observed tumor tissues compared with non-malignant adjacent mucosa, while miR-4647 (P=0.05) showed an opposite trend. Higher expression levels of MUC13 (log-rank P=0.05) were associated with worse patient's survival. The ectopic overexpression of studied miR resulted in decreased migratory abilities and worse survival of cells. Attenuated MUC13 expression levels confirmed the suppression of colony forming of CRC cells. In summary, the present data suggested the essential role of MUC13-miR-4647 in patients' survival, and this axis may serve as a novel therapeutic target. It is anticipated MUC13 may hold significant potential in the screening, diagnosis and treatment of CRC.

Are ovine and porcine carotid arteries equivalent animal models for experimental cardiac surgery: A quantitative histological comparison

BACKGROUND

Coronary artery bypass grafting (CABG) is a common cardiac surgery. Manufacturing small-diameter (2-5mm) vascular grafts for CABG is important for patients who lack first-choice autologous arterial, or venous conduits. Ovine and porcine common carotid arteries (CCAs) are used as large animal models for in vivo testing of newly developed tissue-engineered arterial grafts. It is unknown to what extent these models are interchangeable and whether the left and right arteries of the same subjects can be used as experimental controls. Therefore, we compared the microscopic structure of paired left and right ovine and porcine CCAs in the proximodistal direction and compared these animal model samples to samples of human coronary arteries (CAs) and human internal thoracic arteries (ITAs).

METHODS

We compared the histological composition of whole CCAs of sheep (n=22 animals) with whole porcine CCAs (n=21), segments of human CAs (n=21), and human ITAs (n=21). Using unbiased sampling and stereological methods, we quantified the fractions of elastin, total collagen, type I collagen, type III collagen, smooth muscle actin (SMA) and chondroitin sulfate (CS) A, B, and C. We also quantified the densities and distributions of nuclear profiles, nervi vasorum and vasa vasorum as well as the thickness of the intima-media and total wall thickness.

RESULTS

The differences between the paired samples of left and right CCAs in sheep were substantially greater than the differences in laterality in porcine CCAs. The right ovine CCAs had a smaller fraction of elastin (p<0.001), greater fraction of SMA (p<0.01), and greater intima-media thickness (p<0.001) than the paired left side CCAs. In pigs, the right CCAs had a greater fraction of elastin (p<0.05) and a greater density of vasa vasorum in the media (p<0.001) than the left-side CCAs. The fractions of elastin and CS decreased and the fraction of SMA increased in the proximodistal direction in both the ovine (p<0.001) and porcine (p<0.001) CCAs. Ovine CCAs had a muscular phenotype along their entire length, but porcine CCAs were elastic-type arteries in the proximal segments but muscular type arteries in middle and distal segments. The CCAs of both animals differed from the human CAs and ITAs in most parameters, but the ovine CCAs had a comparable fraction of elastin and CS to human ITAs.

CONCLUSIONS

From a histological point of view, ovine and porcine CCAs were not equivalent in most quantitative parameters to human CAs and ITAs. Left and right ovine CCAs did not have the same histological composition, which is limiting for their mutual equivalence as sham-operated controls in experiments. These differences should be taken into account when designing and interpreting experiments using these models in cardiac surgery. The complete morphometric data obtained by quantitative evaluation of arterial segments were provided to facilitate the power analysis necessary for justification of the minimum number of samples when planning further experiments. The middle or distal segments of ovine and porcine CCAs remain the most realistic and the best characterized large animal models for testing artificial arterial CABG conduits.

Hyperbaric oxygen enhances collagen III formation in wound of ZDF rat

Diabetic foot ulcer (DFU) is a serious complication of diabetes and hyperbaric oxygen therapy (HBOT) is also considered in comprehensive treatment. The evidence supporting the use of HBOT in DFU treatment is controversial. The aim of this work was to introduce a DFU model in ZDF rat by creating a wound on the back of an animal and to investigate the effect of HBOT on the defect by macroscopic evaluation, quantitative histological evaluation of collagen (types I and III), evaluation of angiogenesis and determination of interleukin 6 (IL6) levels in the plasma. The study included 10 rats in the control group (CONT) and 10 in the HBOT group, who underwent HBOT in standard clinical regimen. Histological evaluation was performed on the 18th day after induction of defect. The results show that HBOT did not affect the macroscopic size of the defect nor IL6 plasma levels. A volume fraction of type I collagen was slightly increased by HBOT without reaching statistical significance (1.35+/-0.49 and 1.94+/-0.67 %, CONT and HBOT, respectively). In contrast, the collagen type III volume fraction was ~120 % higher in HBOT wounds (1.41+/-0.81 %) than in CONT ones (0.63+/-0.37 %; p=0.046). In addition, the ratio of the volume fraction of both collagens in the wound ((I+III)w) to the volume fraction of both collagens in the adjacent healthy skin ((I+III)h) was ~65 % higher in rats subjected to HBOT (8.9+/-3.07 vs. 5.38+/-1.86 %, HBOT and CONT, respectively; p=0.028). Vessels density (number per 1 mm2) was found to be higher in CONT vs. HBOT (206.5+/-41.8 and 124+/-28.2, respectively, p<0.001). Our study suggests that HBOT promotes collagen III formation and decreases the number of newly formed vessels at the early phases of healing.

Bioadhesives for musculoskeletal tissue regeneration

Natural or synthetic materials designed to adhere to biological components, bioadhesives, have received significant attention in clinics and surgeries. As a result, there are several commercially available, FDA-approved bioadhesives used for skin wound closure, hemostasis, and sealing tissue gaps or cracks in soft tissues. Recently, the application of bioadhesives has been expanded to various areas including musculoskeletal tissue engineering and regenerative medicine. The instant establishment of a strong adhesion force on tissue surfaces has shown potential to augment repair of connective tissues. Bioadhesives have also been applied to secure tissue grafts to host bodies and to fill or seal gaps in musculoskeletal tissues caused by injuries or degenerative diseases. In addition, the injectability equipped with the instant adhesion formation may provide the great potential of bioadhesives as vehicles for localized delivery of cells, growth factors, and small molecules to facilitate tissue healing and regeneration. This review covers recent research progress in bioadhesives as focused on their applications in musculoskeletal tissue repair and regeneration. We also discuss the advantages and outstanding challenges of bioadhesives, as well as the future perspective toward regeneration of connective tissues with high mechanical demand.

Neomedia Repair of the Valsalva Sinus in the Treatment of Acute Type-A Aortic Dissection: Long-term Effectiveness and a Case of Pathology

Although numerous surgical techniques are employed to treat acute Stanford type A aortic dissection (ATAAD), controversy remains over which is the best procedure for aortic root reconstruction. Among the various techniques utilized, neomedia repair is considered to be more promising than adhesive-only repair for the treatment of a dissected aortic root. We experienced a series of neomedia sinus Valsalva repair using woven polyester fabric, and evaluated the aortic root diameter by computed tomography and severity of aortic valve insufficiency by transthoracic echocardiography. The aortic root diameter was well preserved with no progress of aortic valve insufficiency in the long-term period. Furthermore, we found that the fabric looked functioning new media in the findings obtained from the pathological examination of a neomedia repaired aortic wall sample that was obtained by chance from a patient during valve replacement surgery performed 10 years after aortic reconstruction for ATAAD. Neomedia repair using woven polyester fabric for ATAAD might facilitate the long-term durability of the surgically treated aortic root. (This is a translation of J Jpn Coll Angiol 2019; 59: 37–43.)

The recent progress of tissue adhesives in design strategies, adhesive mechanism and applications

Tissue adhesives have emerged as an effective method for wound closure and hemostasis in recent decades, due to their ability to bond tissues together, preventing separation from one tissue to another. However, existing tissue adhesives still have several limitations. Tremendous efforts have been invested into developing new tissue adhesives by improving upon existing adhesives through different strategies. Therefore, highlighting and analyzing these design strategies are essential for developing the next generation of advanced adhesives. To this end, we reviewed the available strategies for modifying traditional adhesives (including cyanoacrylate glues, fibrin sealants and BioGlue), as well as design of emerging adhesives (including gelatin sealants, methacrylated sealants and bioinspired adhesives), focusing on their structures, adhesive mechanisms, advantages, limitations, and current applications. The bioinspired adhesives have numerous advantages over traditional adhesives, which will be a wise direction for achieving tissue adhesives with superior properties.

Histological mapping of porcine carotid arteries - An animal model for the assessment of artificial conduits suitable for coronary bypass grafting in humans

BACKGROUND

Using animal models in experimental medicine requires mapping of their anatomical variability. Porcine common carotid arteries (CCA) are often preferred for the preclinical testing of vascular grafts due to their anatomical and physiological similarity to human small-diameter arteries. Comparing the microscopic structure of animal model organs to their human counterparts reveals the benefits and limitations of translational medicine.

METHODS

Using quantitative histology and stereology, we performed an extensive mapping of the regional proximodistal differences in the fractions of elastin, collagen, and smooth muscle actin as well as the intima-media and wall thicknesses among 404 segments (every 1 cm) of porcine CCAs collected from male and female pigs (n = 21). We also compared the microscopic structure of porcine CCAs with segments of human coronary arteries and one of the preferred arterial conduits used for the coronary artery bypass grafting (CABG), namely, the internal thoracic artery (ITA) (n = 21 human cadavers).

RESULTS

The results showed that the histological structure of left and right porcine CCA can be considered equivalent, provided that gross anatomical variations of the regular branching patterns are excluded. The proximal elastic carotid (51.2% elastin, 4.2% collagen, and 37.2% actin) transitioned to more muscular middle segments (23.5% elastin, 4.9% collagen, 54.3% actin) at the range of 2-3 centimeters and then to even more muscular distal segments (17.2% elastin, 4.9% collagen, 64.0% actin). The resulting morphometric data set shows the biological variability of the artery and is made available for biomechanical modeling and for performing a power analysis and calculating the minimum number of samples per group when planning further experiments with this widely used large animal model.

CONCLUSIONS

Comparison of porcine carotids with human coronary arteries and ITA revealed the benefits and the limitations of using porcine CCAs as a valid model for testing bioengineered small-diameter CABG vascular conduits. Morphometry of human coronary arteries and ITA provided more realistic data for tailoring multilayered artificial vascular prostheses and the ranges of values within which the conduits should be tested in the future. Despite their limitations, porcine CCAs remain a widely used and well-characterized large animal model that is available for a variety of experiments in vascular surgery.

Aortic α-smooth muscle actin expressions in aortic disorders and coronary artery disease: An immunohistochemical study

Objective:

The is to report immunohistochemical observations of aortic α-smooth muscle actin (SMA) expressions in patients with aortic aneurysm, acute aortic dissection, and coronary artery disease and to discuss phenotypic switching of smooth muscle cells (SMCs) of these lesions.

Methods:

Forty-nine consecutive patients scheduled for surgical treatment for acute type A aortic dissection (20 patients), aortic aneurysm (9 patients), and coronary artery disease (20 patients) were included. Surgical specimens of the aorta were obtained and prepared for hematoxylin and eosin and immunohistochemical stainings.

Results:

A comparison of aortic structural changes between the three groups showed that patients with coronary artery disease had the least severe aorta degeneration with the most intense α-SMA positivity. Aortic structural impairment was the most severe in patients with aortic dissection, whereas α-SMA positivity was more intense in patients with aortic dissection than in those with aortic aneurysm.

Conclusion:

Disparities in α-SMA expressions in the aortic tissues of the three groups represent the extent of SMC degenerations or a phenotypic switching between contractile and synthetic SMCs. The results imply severe SMC degenerations in patients with aortic aneurysm, which may be beneficial because of the production of extracellular matrix necessary for healing of the vascular wall, but severe disruptions in elastic fibers in patients with aortic dissection. Patients with coronary artery disease show slight SMC degeneration and phenotypic switching among the three groups. The possible apoptotic and genetic mechanisms of aortic structural impairments warrant further elaborations.

Novel hemostatic agents based on gelatin-microbial transglutaminase mix

Hemostasis is a major challenge in surgical procedures and traumas. Conventional hemostatic methods have limited efficacy and may cause additional tissue damage. In this study, we designed a novel hemostatic agent based on the in situ gel formation of gelatin cross-linked by a novel microbial transglutaminase (mTGase), in which the amino acid sequences differed from commercial mTGases. The new hemostatic agent showed the same biochemical crosslinking chemistry as the final stages of the blood coagulation cascade while using gelatin as a "structural" protein (rather than fibrin) and a calcium-independent mTGase as the crosslinking catalyst (rather than factor XIIIa). In rat liver hemostasis models, the hemostatic agent not only showed a similar hemostatic effect as that of SURGIFLO^® (positive control), but also stronger adhesion strength and elasticity than SURGIFLO^®. Therefore, this biomimetic gelatin-mTGase mix hemostatic is a novel and effective surgical sealant.

Enhanced sealing strength of a hydrophobically-modified Alaska pollock gelatin-based sealant

A novel tissue sealant composed of hydrophobically-modified Alaska pollock gelatin and polyethylene glycol-based crosslinker showed higher sealing effect than commercially available tissue sealant.

How many Layers has the Adventitia? - Structure of the Arterial Tunica Externa Revisited

Tunica adventitia or tunica externa is the outer layer of the blood vessel wall. It consists of connective tissue with vasa and nervi vasorum and plays a key role in vascular health. The aim of our study was to compare the wall layers beyond tunica media in arteries of different type and location. The following arteries of pig, dog and cat were processed histologically and analysed by light microscopy: aorta ascendens, arcus aortae, aorta thoracica, aorta abdominalis, arteria (a.) femoralis, a. tibialis cranialis, a. carotis communis, a. lingualis, a. basilaris, a. cerebralis media, a. testicularis and aa. jejunales. We found two layers of connective tissue outside the media: (1) a compact layer with many elastic fibres in muscular and few in elastic arteries and (2) an outer layer of loose connective tissue. The compact layer was missing in aorta ascendens, arcus aortae and intracranial vessels. Adventitial stripping removed only the loose connective tissue layer. In spite of the still present compact layer, stripped arteries were very flimsy. We suggest using the term 'tunica externa' for the compact connective tissue layer and 'tunica adventitia' for the outermost loose connective tissue layer as in other organs. The presence of the tunica externa differs between species, arteries and arterial side, as well as the removability of tunica adventitia and tunica externa by anatomical dissection.

Novel Technique Using Polyester Fabric and Fibrin Sealant Patch for Acute Aortic Dissection

We describe a simple and effective technique for acute aortic dissection using a combination of polyester fabric and a fibrin sealant patch (FSP) to achieve effective reinforcement and haemostasis of the aortic stump. Firstly, the 0.61mm thick knitted polyester fabric sheet was cut to half of the size of the FSP. Next, fibrin glue was sprayed onto the collagen layer of the FSP. Subsequently, a fabric sheet was placed upon it, and the FSP was put together with the irrigated collagen layer, and then completely dried to bind the patch. As a result, the dry fibrinogen/thrombin layers, as an adhesive surface, faced outward. This patch was trimmed to a 10-15-mm-wide strip. The composite patch was inserted into the false lumen. The stump was gently pressed to fix the aortic intima and adventitia. There are several advantages: the combined patch can be prepared during systemic cooling, and therefore can minimise the circulatory arrest time; secondly, the false lumen is not directly exposed to fibrin glue and so the risk of embolism is extremely low; thirdly, the expected haemostatic effect is greater as FSP lines the exterior of the intima, achieving haemostasis for suture holes.

Clinical, mechanical, and immunohistopathological effects of tissue adhesives on the colon: An in-vivo study

BACKGROUND

Tissue adhesives may be useful for sealing bowel anastomoses by preventing anastomotic leakage. Prior to clinical implementation, an in-depth analysis of the clinical and immunohistopathological effects of tissue adhesives on the target tissue and of the mechanical strength of the adhesive bond in an in vivo model is needed.

MATERIALS AND METHODS

In 84 rats, two bowel segments were glued using one of the following tissue adhesive: Bioglue, Gelatin-resorcinol-formaldehyde (GRF), Glubran 2, Histoacryl Flex, Omnex, Duraseal Xact, or Tissucol. Rats were followed for 7 or 28 days. Endpoints were clinical complication rate, mechanical strength, and immunohistopathological reactions.

RESULTS

Of the seven tissue adhesives, GRF and Bioglue showed the highest rates of bowel wall destruction and ileus and the most severe immunohistopathological tissue reactions at 7 and 28 days. Cyanoacrylates (Histoacryl Flex, Omnex, Glubran 2) showed high mechanical strength and mild immunohistopathological reactions at 7 and 28 days. Duraseal Xact and Tissucol were the most inert tissue adhesives, but exhibited low mechanical strength. At 28 days, mechanical strength was significantly correlated to CD8, CD68, and Ki67 cell counts.

CONCLUSION

Based on the clinical and immunohistopathological outcomes, GRF and Bioglue were found to be the least suitable tissue adhesives for colonic use. Duraseal Xact and Tissucol were inert but also showed low mechanical strength. Cyanoacrylates exhibited mild clinical and immunohistopathological effects while maintaining high strength, which makes them promising as colonic sealants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 846-854, 2017.

Surgical adhesive BioGlue™ does not benefit tendon repair strength: an ex vivo study

Surgical adhesives are useful supplements in surgery, but their benefit in tendon repair is uncertain. The purpose of this study was to evaluate the effect of BioGlue™ on strength of flexor tendon repair. A total of 60 porcine flexor tendons were divided into three groups. In group one, a conventional core and peripheral suture repair was used. In group two, a core suture and BioGlue™ were used. In group three, a conventional core and peripheral suture repair and BioGlue™ were used. We performed static and cyclic axial load testing and measured diameter of the repair site. We found that BioGlue™ did not improve the tensile strength when added to a core and peripheral suture and that there was an increase in bulk at the repair site. We conclude that BioGlue™ application cannot replace a peripheral suture as tensile strength significantly decreases without a peripheral suture, and it does not benefit a tendon already repaired with a core and peripheral suture.

LEVEL OF EVIDENCE

n/a.

Vascular histopathologic reaction to pulmonary artery banding in an in vivo growing porcine model

Pulmonary artery banding (PAB) is used as a surgical palliation to reduce excessive pulmonary blood flow caused by congenital heart defects. Due to the lack of microscopic studies dealing with the tissue remodeling caused by contemporary PAB materials, this study aimed to assess histologic changes associated with PAB surgery by analyzing local tissue reaction to the presence of Gore-Tex strips fixed around the pulmonary artery. Gore-Tex strips were used for PAB in a growing porcine model. After 5 weeks, histologic samples with PAB (n = 5) were compared with healthy pulmonary arterial segments distal to the PAB or from a sham-treated animal (n = 1). Stereology was used to quantify the density of the vasa vasorum and the area fraction of elastin, smooth muscle actin, macrophages, and nervi vasorum within the pulmonary arterial wall. The null hypothesis stated that samples did not differ histopathologically from adjacent vascular segments or sham-treated samples. The PAB samples had a greater area fraction of macrophages, a lower amount of nervi vasorum, and a tendency toward decreased smooth muscle content compared with samples that had no PAB strips. There was no destruction of elastic membranes, no medionecrosis, no pronounced inflammatory infiltration or foreign body reaction, and no vasa vasorum deficiency after the PAB. All the histopathologic changes were limited to the banded vascular segment and did not affect distal parts of the pulmonary artery. The study results show the tissue reaction of palliative PAB and suggest that Gore-Tex strips used contemporarily for PAB do not cause severe local histologic damage to the banded segment of the pulmonary arterial wall after 5 weeks in a porcine PAB model.

Fibrin sealant patch for repair of acute type a aortic dissection

INTRODUCTION

The use of glues to repair disrupted tissue during acute type-A aortic dissection (TAD) surgery may be discontinuous, and cause embolization and cell necrosis. We report a method of fibrin sealant patch (FSP) to reinforce dissected aortic tissue with a collagen double layer coated with fibrinogen/thrombin on either side (TachoSil®; Takeda, Konstanz, Germany).

METHODS

In 12 patients (seven male, 66.9 ± 11.7 years) with acute TAD we performed FSP of the intima-media disruption at the proximal and distal anastomosis of the aorta. We analyzed the perioperative course and echocardiographical, radiological, and clinical outcomes up to one year. Additionally, we investigated the adhesive potential of the FSP in vitro.

RESULTS

In vitro, the adhesive strength of the FSP was 60 N/cm(2). In-hospital mortality was 8.3% (n = 1), recovery was satisfactory with no major neurologic events, mean ICU stay was 13.6 ± 6.0 days, mean hospital stay was 20.7 ± 4.4 days. A total of 7.0 ± 2.6 RBC, 3.4 ± 1.5 platelets, and 8.0 ± 4.3 FFP were transfused. One-year survival was 83.3%. In 6/6 DeBakey II dissections the intimal tear was completely resected, in 2/6 DeBakey I dissections the false lumen in the descending aorta completely collapsed. No redissections and no relevant aortic valve insufficiencies were seen during follow-up.

CONCLUSION

This analysis shows that FSP using a collagen matrix double layer coated with fibrinogen/thrombin is feasible, safe, and effective in repairing the dissected aortic tissue. It results in continuous reinforcement of aortic tissue and completely avoids the need for conventional glues.

A case of ascending aortic pseudoaneurysm in a patient with aortic replacement

A 59-year-old man with a history of ascending aorta replacement for an aortic dissection using gelatin-resorcin-formalin glue at age of 50 years presented with paroxysmal nocturnal dyspnea. An echocardiogram showed severe aortic regurgitation associated with aortic root enlargement. Chest computed tomography showed that the ascending aorta was dilated and a pseudoaneurysm was observed around the implanted prosthetic graft. Upon opening the ascending aorta, we found that the posterior wall of the proximal anastomotic portion of the implanted graft was ruptured. After replacement of the aortic root with a composite graft and reconstruction of the orifices of the right and left coronary arteries, total arch replacement by the separated graft technique was performed. The postoperative course was uneventful.

Vasa vasorum quantification in human varicose great and small saphenous veins

Recent research regarding saphenous vasa vasorum (VV) has focused on two main topics: the VV during varicogenesis in chronic venous insufficiency and the VV in saphenous grafts used in reconstructive vascular surgery. Our aim has been (i) to establish a technique for the histological quantification of the VV in human varicose great and small saphenous veins and (ii) to describe the density and distribution of the vasa vasorum within varicose veins. Great (n=11) and small (n=5) saphenous veins (length, 15-40cm) were collected from 12 patients who were undergoing venous stripping due to chronic venous insufficiency (Clinical-Etiology-Anatomy-Pathophysiology class 2-3). The veins were divided into 5-cm long segments. In total, 92 tissue blocks were collected to trace the variability of the density and distribution of the vasa vasorum in the proximo-distal direction. The endothelium was detected by immunohistochemistry using the von Willebrand factor. We quantified the number of microvessel profiles per section area and the relative distance of the microvessels from the outer border of the adventitia. The VV did not exhibit a preferential orientation in the varicose veins. VV density profiles were highest in the middle third of the venous wall and lowest in the inner third of the venous wall. Both the density and distribution of VV were uniform along the veins, and no differences were observed between the great and small saphenous veins. The VV density was statistically independent of the relative distance from the adventitia. The usability of this technique for perioperative frozen sections remains to be tested.

A highly elastic and adhesive gelatin tissue sealant for gastrointestinal surgery and colon anastomosis

BACKGROUND

We describe the development of a highly elastic and adhesive surgical tissue sealant, based on photochemically crosslinked gelatin, for sealing sutured incisions in the gastrointestinal (GI) tract in a rabbit surgical model and in a canine colon anastomosis study.

METHODS

The study included in vitro assessment of mechanical parameters of the tissue sealant and in vivo analysis of burst strength and histology at 24 h, 3 days and 7 days post surgery, in a rabbit model, to assess progress of wound healing at the suture sites. Utility of this sealant to repair and seal a lower colonic resection and anastomosis procedure in a canine model was also investigated.

RESULTS

We show that a photopolymerised gelatin tissue sealant provides effective sealing of GI incisions and facilitates wound healing with no evidence of inflammation up to 28 days post-surgery. Blending of derivatised gelatin with underivatised gelatin allowed tuning of elasticity and elastic modulus of the photopolymerised sealant to suit surgical applications. High tissue adhesive strength was maintained at all blend ratios and exceeded 100 kPa.

CONCLUSIONS

This highly elastic and adhesive photopolymerised gelatin tissue sealant offers a number of advantages over currently available sealants suitable for GI surgical procedures.

Early and late results of surgical treatment for ventricular septal rupture with and without use of the infarction exclusion technique--experience with two- and three-sheet modification

BACKGROUND

Ventricular septal rupture (VSR) is an infrequent but life-threatening situation. Although outcomes have improved with the introduction of infarction exclusion, we have experienced difficulty in determining the optimal patch size and shape for obtaining good outcomes. Therefore, we modified the infarction exclusion technique. Herein, we review our experience on the basis of early closure of VSR with and without use of the infarction exclusion technique.

METHODS

We retrospectively analyzed the hospital records of 33 patients who underwent surgical treatment for VSR. We employed Dagget's method from 1982 to 1995, and then introduced the infarction exclusion technique in 1995. We have developed two modifications: the two-sheet single-patch technique and the three-sheet double-patch technique.

RESULTS

Overall hospital mortality was 41.9% and that of the infarction exclusion group was significantly lower than the hospital mortality rate of the noninfarction exclusion group (21% and 63%, respectively, p = 0.0266). Late mortality of survivors was low in all groups during the observation period. The three-sheet double-patch group showed no residual shunt. This difference in outcomes between the single-patch and double-patch groups was statistically significant (p = 0.0174).

CONCLUSIONS

The two-sheet method facilitates the restoration of ventricular geometry. A double-patch using the three-sheet method may be useful for reducing residual shunt.

Initial stability of two different adhesives compared to suture repair for acute Achilles tendon rupture--a biomechanical evaluation

PURPOSE

Treatment of acute subcutaneous Achilles tendon rupture remains challenging. Whereas the results of conservative and operative treatment are inconsistent, early mobilisation treatment seems to be beneficial. Besides suture repair, operative treatment using adhesives reveals promising results. Our hypothesis was that a gluing technique provides initial stability comparable to sutures.

METHODS

In a biomechanical study, 18 fresh frozen sheep Achilles tendons were used to compare the biomechanical properties of suture repair using PDS® II and Bunnell's technique to tendon gluing using BioGlue® and Tissucol®. Load to failure testing was performed.

RESULTS

Ultimate failure loads of sutures (146.2 ± 30.8 N) are significantly superior to the techniques using BioGlue® (38.4 ± 18.3 N; p <0.0001) or Tissucol® (4.7 ± 2.5 N; p <0.0001). Interestingly, no significant differences in stiffness were found between the application of BioGlue® and PDS® II.

CONCLUSIONS

Suture repair provides significantly superior biomechanical properties compared to the use of both tested adhesives BioGlue® and Tissucol®. Based on the presented data we recommend the use of suture material for open Achilles tendon repair.

Histochemistry and cell biology: the annual review 2010

This review summarizes recent advances in histochemistry and cell biology which complement and extend our knowledge regarding various aspects of protein functions, cell and tissue biology, employing appropriate in vivo model systems in conjunction with established and novel approaches. In this context several non-expected results and discoveries were obtained which paved the way of research into new directions. Once the reader embarks on reading this review, it quickly becomes quite obvious that the studies contribute not only to a better understanding of fundamental biological processes but also provide use-oriented aspects that can be derived therefrom.