Minimal Tissue Reaction Research Articles

(018) Long Term Outcome of Tachosil Patching of the Penile Tunica Albuginea Defect in the Dog: Histological and Hemodynamic Results

Abstract Introduction The need for patching of the penile tunica albuginea (TA) might arise during surgery for Peyronie’s disease with or without a penile prosthesis. Clinically, TachoSil has evolved as an off-the-shelf hemostatic graft that does not need suturing. Results in patients are encouraging. However, its histopathological fate and its impact on the hemodynamics of erection are not known. Objective We evaluate the long-term histopathology and pharmacologically induced erection after Tachosil patching of the TA in dogs. Methods Under general anesthesia, the penis of two adult male beagle dogs was dissected through a midline incision, and TA was exposed. The femoral artery was cannulated and connected to an invasive pressure monitor to record BP. Intracavernous pressure (ICP) was measured on each cavernous side separately, as a complete septum isolates the two compartments of the penis. A 21-gauge butterfly needle was placed on either side proximally. Five minutes were allowed before taking baseline ICP. Ten mg of papaverine hydrochloride was injected intracavernosal. ICP was measured at 2 to10-min time points. On the left side, 2 cm proximal to the glans of the penis, a full-thickness defect was created in TA 1 cm long and 0.5 cm wide (Fig. 1. A, B &C). Four transverse incisions 1 cm long were made on the right side and placed 0.5 cm apart, exposing the corpus cavernosum (Fig. 1. D). A Tachosil patch (Takeda, Japan) was fashioned and applied to cover the defects. Proline 5/0 sutures were placed, marking the proximal and distal ends of the graft areas. The fascia, subcutaneous tissue, and skin were closed with absorbable sutures. Six months later, each dog was anesthetized, and the penis was dissected free from the covering fascia. Invasive BP and ICP measurements were repeated at baseline and after 10 mg papaverine injection. Silk and proline sutures were placed to identify the distal end and the left side of the penis. The penis was excised from the base of the glans penis distally to its root, at least 6 cm proximally and fixed in 10% formaldehyde solution. Transverse blocks of the penis were cut at 3 mm intervals and fixed in paraffin. Sections from each block were stained with H&E and trichrome and examined by a urology pathologist. Descriptive statistics are provided. Results Gross appearance showed a well-healed scar, and the subcutaneous tissue did not show significant adhesions. The graft site was impossible to distinguish, and the sutures were not visible. ICP measurement did not show a drop in pressure pre- and post-surgery (Fig. 2). Histologically, minimal foreign body reaction was seen, and the tunica albuginea was completely regenerated (Fig. 3). The underlying cavernous tissue did not show inflammation or necrosis. Conclusions Long-term histological results of Tachosil patching in the dog show complete tunica albuginea regeneration with minimal tissue reaction and no underlying cavernous tissue pathology. Hemodynamically the intracavernous pressure response to papaverine is maintained. Although only two animals are presented here, the results are striking. Further experimentation with more animals is warranted to support these findings. Disclosure No.

Chitosan thread in the healing of the cecal wall of rabbits (Oryctolagus cuniculus) submitted to cecorrhaphy.

The development and evaluation of synthesis materials are crucial to reducing the morbidity and magnitude of post-enterorrhaphy surgical complications. Despite the possibility of production, chitosan thread has not yet been used in enterorrhaphy, and its effects on intestinal healing have not been evaluated. Therefore, this study aimed to evaluate the effects of chitosan thread on the intestinal wall repair of rabbits submitted to cecorrhaphy. For this, 42 rabbits were allocated into two groups with 21 animals. One group was submitted to cecorrhaphy with chitosan suture thread (CG) and the other with poliglecaprone suture thread (PG). The occurrence of postoperative complications, the intensity of edema, cellular response, formation of granulation tissue, as well as the deposition and maturation of collagen fibers, and the intensity of vascular endothelial growth factor (VEGF-α) expression, were evaluated during the intestinal wall repair process. The evaluations occurred on the 5th, 15th, and 25th postoperative (PO) days. The animals did not develop peritonitis, but adherence was observed in six animals from CG and seven from PG, with no difference between groups. The polymorphonuclear infiltrate showed higher intensity and higher amount of type III collagen fibers in CG on the 15th PO day. In contrast, a lower amount of type I collagen fibers was observed in CG samples on the 25th PO day. Therefore, the chitosan thread used for cecorrhaphy in rabbits results in minimal postoperative complications, presents biocompatibility, and bioactively assists the tissue repair process of the cecal wall, inducing minimal tissue reaction, stimulating the deposition of type III collagen fibers in the proliferative phase, with sustained VEGF-α expression, but with reduced deposition of type I fibers, indicating a delay in collagen maturation.

Comparison of Scar Quality using Polyglactin and Polyamide Suture Materials for Closure of Nasolabial Flap Donor Site Defects in Patients with Oral Submucous Fibrosis: A Research Protocol

Introduction: Scar formation is an unavoidable sequelae of any surgical procedure. The goal is to produce fine scars with the least complications. Literature mentions various surgical factors that may lead to better quality of scars, one of which is the type of suture material used. Few studies exist in the literature that have compared the quality of scars after placement of polyglactin and polyamide sutures. Additionally, no studies have been done to compare the quality of scars following reconstruction with nasolabial flaps in patients with oral submucous fibrosis. Need for the study: This study will help evaluate and establish the healing outcomes in nasolabial flaps in the form of scars after placing subcutaneous 4-0 polyglactin (VICRYL™ ETHICON) and 4-0 polyamide (ETILONTM ETHICON) sutures. This will eventually lead to minimal tissue reaction and more aesthetic scars with fewer complications. Aim: To evaluate and compare the quality of scars postreconstruction with nasolabial flaps with subcutaneous polyglactin sutures and subcutaneous polyamide sutures. Materials and Methods: This is a prospective randomised triple-blinded trial which will be conducted in the Department of Oral and Maxillofacial Surgery, Sharad Pawar Dental College and Hospital (SPDCH), Sawangi (Meghe), Wardha, India. The trial will take place from July 2023 to June 2024. A total of 15 subjects with grade C Oral and Submucous Fibrosis (OSMF), who will undergo fibrotomy followed by reconstruction of bilateral nasolabial flaps, will be enrolled in the trial. Suturing of one side of the flap will be done using 4-0 polyglactin (VICRYL™ ETHICON) suture subcutaneously, and the other side will use 4-0 polyamide (Ethilon™ ETHICON) suture subcutaneously. The scar tissues will be periodically evaluated at one week, one month, and three months postoperative period to assess the healing outcomes and overall aesthetic appearance using the Patient and Observer Scar Assessment Scale (POSAS) using Chi-square test and Student’s t-test.

Manufacturing Processes of Implantable Microelectrode Array for In Vivo Neural Electrophysiological Recordings and Stimulation: A State-Of-the-Art Review.

Electrophysiological recording and stimulation of neuron activities are important for us to understand the function and dysfunction of the nervous system. To record/stimulate neuron activities as voltage fluctuation extracellularly, microelectrode array (MEA) implants are a promising tool to provide high temporal and spatial resolution for neuroscience studies and medical treatments. The design configuration and recording capabilities of the MEAs have evolved dramatically since their invention and manufacturing process development has been a key driving force for such advancement. Over the past decade, since the White House Brain Research Through Advancing Innovative Neurotechnologies (BRAIN) Initiative launched in 2013, advanced manufacturing processes have enabled advanced MEAs with increased channel count and density, access to more brain areas, more reliable chronic performance, as well as minimal invasiveness and tissue reaction. In this state-of-the-art review paper, three major types of electrophysiological recording MEAs widely used nowadays, namely, microwire-based, silicon-based, and flexible MEAs are introduced and discussed. Conventional design and manufacturing processes and materials used for each type are elaborated, followed by a review of further development and recent advances in manufacturing technologies and the enabling new designs and capabilities. The review concludes with a discussion on potential future directions of manufacturing process development to enable the long-term goal of large-scale high-density brain-wide chronic recordings in freely moving animals.

Minimal Tissue Reaction after Chronic Subdural Electrode Implantation for Fully Implantable Brain-Machine Interfaces.

There is a growing interest in the use of electrocorticographic (ECoG) signals in brain–machine interfaces (BMIs). However, there is still a lack of studies involving the long-term evaluation of the tissue response related to electrode implantation. Here, we investigated biocompatibility, including chronic tissue response to subdural electrodes and a fully implantable wireless BMI device. We implanted a half-sized fully implantable device with subdural electrodes in six beagles for 6 months. Histological analysis of the surrounding tissues, including the dural membrane and cortices, was performed to evaluate the effects of chronic implantation. Our results showed no adverse events, including infectious signs, throughout the 6-month implantation period. Thick connective tissue proliferation was found in the surrounding tissues in the epidural space and subcutaneous space. Quantitative measures of subdural reactive tissues showed minimal encapsulation between the electrodes and the underlying cortex. Immunohistochemical evaluation showed no significant difference in the cell densities of neurons, astrocytes, and microglia between the implanted sites and contralateral sites. In conclusion, we established a beagle model to evaluate cortical implantable devices. We confirmed that a fully implantable wireless device and subdural electrodes could be stably maintained with sufficient biocompatibility in vivo.

XEN® Gel Stent: A Comprehensive Review on Its Use as a Treatment Option for Refractory Glaucoma.

The XEN Gel Microstent is a subconjunctival microinvasive glaucoma surgical device developed with the aim of improving the predictability and safety profile of bleb-forming glaucoma surgical procedures. The stent is a hydrophilic tube composed of a porcine gel cross-linked with glutaraldehyde with good stability and biocompatibility with minimal tissue reaction. This device has demonstrated promising outcomes with fewer risks compared to traditional surgeries. The aim of the review is to present early studies on different designs of the XEN Gel Stent, to summarize different surgical techniques of implantation and to analyze more comprehensively the results, complications and rates of needling of the commercially available device (Xen 45). The review will address separately special cases (PXG, UVG, ICE, congenital glaucoma) and describe small series and case reports.

MP60-20 DEVELOPMENT OF A LARGE ANIMAL URETHRAL STRICTURE MODEL IN CANINES

INTRODUCTION AND OBJECTIVE: Male urethral stricture disease (USD) is a relatively common condition that can lead to significant voiding symptoms requiring multiple endoscopic and open procedures. Existing pre-clinical models of USD are limited to small animals. We sought to develop a large animal urethral model in canines for testing and validating future diagnostic and therapeutic innovations. METHODS: 3 canines (Marshall Bioresourcers, 25-30 Kgs, 9-12 months old) underwent scrotal urethrostomy for urethral access and urine diversion. Following a 3-4 week recovery period, a pre-intervention retrograde urethrogram (RUG) was performed. Circumferential thermocoagulation of the defunctionalized distal urethral segment was performed using pediatric resectoscope (Karl Storz, Tuttlingen, Germany) for 30-45 sec in intermittent bursts at 25-30 W power setting, until visible blanching with minimal tissue reaction was observed. Further cystoscopic, radiographic and perfusion (Moor laser Doppler Flowmetry; LDF) monitoring was performed at 2 & 8 week intervals before subsequent euthanasia and tissue harvest. Histologic examination was performed using H&E, Hart’s and Gomori’s trichrome stains. RESULTS: Comparative analysis between pre & post RUG indicated an average 50% reduction in urethral caliber which was confirmed via cystoscopic evaluations. Histologically, the urethral lumen was markedly narrowed, and the corpora spongiosa was largely replaced by proliferating fibroblasts and mature collagen. CONCLUSIONS: We describe the first successful urethral stricture disease model in an anatomically-comparable and physiologically-similar large animal. This pre-clinical model will facilitate development of novel technical and surgical therapy options for USD.Source of Funding: Johns Hopkins Tech Ventures (JHTV) Thalheimer Translational Research Fund

A Collagen Based Cryogel Bioscaffold that Generates Oxygen for Islet Transplantation.

The aim of this work was to develop, characterize and test a novel 3D bioscaffold matrix which can accommodate pancreatic islets and provide them with a continuous, controlled and steady source of oxygen to prevent hypoxia-induced damage following transplantation. Hence, we made a collagen based cryogel bioscaffold which incorporated calcium peroxide (CPO) into its matrix. The optimal concentration of CPO integrated into bioscaffolds was 0.25wt.% and this generated oxygen at 0.21±0.02mM/day (day 1), 0.19±0.01mM/day (day 6), 0.13±0.03mM/day (day 14), and 0.14±0.02mM/day (day 21). Accordingly, islets seeded into cryogel-CPO bioscaffolds had a significantly higher viability and function compared to islets seeded into cryogel alone bioscaffolds or islets cultured alone on traditional cell culture plates; these findings were supported by data from quantitative computational modelling. When syngeneic islets were transplanted into the epididymal fat pad (EFP) of diabetic mice, our cryogel-0.25wt.%CPO bioscaffold improved islet function with diabetic animals re-establishing glycemic control. Mice transplanted with cryogel-0.25wt.%CPO bioscaffolds showed faster responses to intraperitoneal glucose injections and had a higher level of insulin content in their EFP compared to those transplanted with islets alone (P<0.05). Biodegradability studies predicted that our cryogel-CPO bioscaffolds will have long-lasting biostability for approximately 5 years (biodegradation rate: 16.00±0.65%/year). Long term implantation studies (i.e. 6 months) showed that our cryogel-CPO bioscaffold is biocompatible and integrated into the surrounding fat tissue with minimal adverse tissue reaction; this was further supported by no change in blood parameters (i.e. electrolyte, metabolic, chemistry and liver panels). Our novel oxygen-generating bioscaffold (i.e. cryogel-0.25wt.%CPO) therefore provides a biostable and biocompatible 3D microenvironment for islets which can facilitate islet survival and function at extra-hepatic sites of transplantation.

Experimental orthotopic implantation of tissue-engineered tracheal graft created based on devitalized scaffold seeded with mesenchymal and epithelial cells

Aim. To study the viability of the tissue-engineered graft (TEG) based on the devitalized tracheal scaffold (DTS), seeded by mesenchymal stromal and epithelial cells in the experiment on rabbits with the assessment of the cytocompatibility and biocompatibility in vivo. Materials and methods. Syngeneic bone marrow-derived mesenchymal stromal cells (BM-MSCs) and lung epithelial cells of rabbit were obtained. Morphology and phenotype of the BMSCs culture were confirmed by immunofluorescent staining on CD90 and CD271 markers. Pulmonary epithelium cells obtained by enzymatic treatment of shredded lung tissue of rabbit were stained with CKPan, CK8/18 and CK14 markers of epithelial cells. The donor trachea was devitalized in three freeze-thawing cycles. Double-layer cell seeding of DTS was performed under static and dynamic culturing. Orthotopic implantation of TEG was performed at the site of the anterolateral wall defect in the rabbit trachea formed as a result of tracheal resection over four rings. The results were evaluated by computed tomography, histological and immunohisto- chemical analyses. Results. TEG implant based on DTS with two-layer cell cultures of rabbit BM-MSCs and epithelial cells was obtained. Three months after the implantation, TEG engraftment was observed, no tracheal wall stenosis was observed, but a slight narrowing of the lumen in the implantation area was observed. Viability of the tissue-engineered graft was confirmed by histological method 6 months after implantation. Epithelialization and vascularization of the tracheal wall, absence of signs of purulent inflammation and aseptic necrosis were shown. Small narrowing of the tracheal lumen was caused by chronic inflammation produced by irritation of the mucous suture material. Conclusion. The new model for evaluating the viability of a tissue engineering implant during critical airway defect closure was obtained. Two-layer vitalization of DTS with lung epithelial cells and BM-MSCs allows to create a tissue engineered structure for replacement of non-long tracheal defects in the experiment in vivo. The use of the tracheal tissue-engineered graft for orthotopic implantation showed a biocompatibility with minimal tissue reaction.

Hemangiosarcoma Associated with Polypropylene Suture in a Cat

Background: Sutures plays an important role in wound repair by providing hemostasis and support for healing suture. Synthetic non-absorbable like polypropylene suture materials induce minimal tissue reaction. Polypropylene has not been associated to neoplasms in domestic animals. The aim this study is to describe the first case of polypropylene suture induced hemangiosarcoma in an abdominal wall of a feline.Case: A 13-year-old female domestic shorthair cat was presented with a ventral abdominal subcutaneous mass. Clinical examination revealed a firm, rough, and irregular, approximately 6 x 4 cm subcutaneous mass involving the caudal ventral abdomen. A complete blood (cell) count (CBC) was within normal limits. Leukemia and FIV tests were negative; andthe results of a chemistry panel revealed elevated creatinine (valor: 2.0 reference range: 0.5-1.9). Abdominal ultrasound revealed a large mass of mixed echogenicity in the mid-ventral abdomen cranial to the bladder, measuring approximately 6 x 4 cm in the middle line with suture deeply embedded within mass suggesting foreign body reaction or neoplasm. There was evidence of sutures (hyperechoic lines) along the caudal abdominal wall extending into the mass. Records indicated that ovariohysterectomy procedure was performed 12 years previously at the same clinic and the closure of the abdominal wall was made with polypropylene sutures. No other abdominal surgery was performed in this cat. A fine-needle aspirate of the mass and contrast-enhanced computed tomography was not performed due to owner’s finance restrains. The catwas referred to surgery and the mass was excised. No evidence of metastasis was noted during surgery. Histologically, the neoplastic cells were oval to round with granular cytoplasm and vesicular nucleus and exhibited moderate cellular and nuclear pleomorphism. A diagnosis of abdominal wall hemangiosarcoma was made with suture deeply embedded within mass. Surgical margins were clear. Chemotherapy was indicated, but the owner declined due to financial reasons. This is the first polypropylene suture mass associated hemangiosarcoma in cats.Discussion: Hemangiosarcoma is a malignant neoplasm of vascular endothelial cells origin and it may be associated with chronic inflammation and neoplastic transformation. It was reported in previous studies, and it could be a hypothesis for the presented clinical case. There are two cases described in the literature of abdominal wall tumor associated with foreignbody and exuberant inflammatory response in cats using different types of suture; one case is a steel staple developing hemangiosarcoma and the other is polyester sutures developed fibrosarcoma. The present study shows a primary hemangiosarcoma diagnosed several years after closure of abdominal wall using polypropylene sutures in a female cat. Polypropylene is a monofilament suture that create less tissue-drag and induces less inflammation than multifilament sutures and is the preferred suture to close abdominal wall. Cats demonstrate a peculiar predisposition to neoplasms at the site of injury. Although the pathogenesis is still unclear, the introduction a “foreign body” may cause inflammatory process that act as a stimulus to neoplasia formation. We believe that polypropylene was the foreign material that may have played arole in tumor development in this case and it has not been reported before. Polypropylene sutures were found on gross examination of excised material. Any uncoated braided non-absorbable material located deeply in tissues may evoke a chronic inflammatory response (granuloma). A granuloma may evolve to malignancy in some cats. Despite polypropylenematerials induce minimal tissue reaction, it may be associated to neoplasm.Keywords: polypropylene suture, hemangiosarcoma, cat, tumor induced by foreign body.

Fracture Healing and Bone Remodeling With Human Standard-Sized Magnesium Versus Polylactide–Co-Glycolide Plate and Screw Systems Using a Mini-Swine Craniomaxillofacial Osteotomy Fixation Model

This study compared the degradation profile, safety, and efficacy of bioresorbable magnesium alloy and polylactide-co-glycolide (PLGA) polymer osteosynthesis systems for the treatment of fractures in a load-sharing maxillofacial environment using a new mini-swine fracture fixation model. Two types of clinically relevant situations were evaluated in 5 Yucatan miniature pigs. Defined porcine midface osteotomies of the supraorbital rim and zygoma were created and fixed with either a coated magnesium (test animals) or PLGA plate and screw osteosynthesis system (control animals). After surgery, the mini-pigs were able to recover for either 1 or 9months with continuous invivo post-implantation monitoring. Standardized computed tomography (CT) imaging was taken immediately postoperatively and at termination for all animals. The 9-month cohort also underwent CT at 2, 4, and 6months after surgery. At necropsy, osteotomy sites and bone-implant units were harvested, and healing was evaluated by micro-CT, histopathology, and histomorphometry. After clinical and radiologic follow-up examination, all fracture sites healed well for both the magnesium and polymer groups regardless of time point. Complete bone union and gradually disappearing osteotomy lines were observed across all implantation sites, with no major consistency change in periprosthetic soft tissue or in soft tissue calcification. Macroscopic and microscopic examination showed no negative influence of gas formation observed with magnesium during the healing process. Histopathologic analysis showed similar fracture healing outcomes for both plating systems with good biocompatibility as evidenced by a minimal or mild tissue reaction. This study confirms that WE43 magnesium alloy exhibited excellent fracture healing properties before its full degradation without causing any substantial inflammatory reactions in a long-term porcine model.Compared with PLGA implants, magnesium represents a promising new biomaterial with reduced implant sizes and improved mechanical properties to support fracture healing in a load-sharing environment.

Application of polycaprolactone nanofibers as patch graft in ophthalmology.

Purpose:The purpose of the study was to evaluate tissue reaction to polycaprolactone (PCL) nanofiber patches in the cornea, conjunctiva, and anterior chamber (AC) in rabbit eyes and to assess their biocompatibility for use as patch grafts.Methods:Two 100 μ PCL patches were implanted under the conjunctiva and in the corneal stroma of one albino New Zealand rabbit, and pathologic evaluation was done after 3 weeks. In the next step, two PCL patches were implanted; one in the corneal stroma and the other in the AC of two rabbits followed by pathologic evaluation after 3 months.Results:On slit-lamp examination, there was minimum inflammation in all cases. Pathologic examination showed that the contact and probably merging between the host tissue and PCL fibers were achieved with minimal tissue reaction.Conclusion:As a biocompatible material, PCL nanofibers seem to be a promising modality for the repair of different tissue defects including melting, thinning, and perforation. They may also be a suitable material for manufacturing keratoprostheses.

Comparative evaluation of pin-in-fiberglass cast and Kirschner-Ehmer external fixative in the management of radius-ulna fractures in dogs

Four adult (two males and two females) dogs were used to comparatively evaluate the effectiveness of pin-in-fiberglass cast with Kirschner-Ehmer type I external skeletal fixative in the management of surgically created radius-ulna fractures in dogs. These dogs were assigned to two groups (A and B) with each group made up of two dogs. The radius-ulna fracture was created in all the dogs under general anaesthesia as follows: Group A, pin-in-fiberglass casting; and Group B, Kirschner-Ehmer type I external fixation. Post-operatively, minimal increase in vital parameters were observed, but were not significant (P&gt;0.05) when compared with pre-operative values in both groups. The haematological indices were within acceptable normal limits for both group (P&gt;0.05). Dogs in both groups bore weight on the operated limb and could walk within 24 hours post-operative. Radiographic evaluation revealed minimal soft tissue swelling and minimal periosteal tissue reaction in both groups. The Kirschner-Ehmer external fixative group attained the faster fracture healing time (7 weeks) compared to the pin-in-fiberglass group (8 weeks). Functional and cosmetic appearances were graded as excellent for both groups. Complications associated with the two techniques were cast sores in the pin-in-fiberglass group while pin loosening and serous pin tract drainage were observed in the Kirschner-Ehmer external fixative group. Thus, it was concluded that pin-in-fiberglass cast could be used as a satisfactory substitute to Kirschner-Ehmer type I external fixative in the management of simple radius-ulna fractures in dogs.Keywords: Bone, Dog, Fracture, Kirschner-Ehmer external fixative, Pin-in-fiberglass cast, Radius-ulna

Initial experiences with a new design for a preattached intravenous port device.

All available conventional ports share a common design, including catheter, locking nut, and port body, and all share two sites of structural weakness. One site is the junction between the locking nut and the proximal end of the catheter. The other site is the catheter fixation site between the locking nut and the protruding stud of the connecting tube. To overcome these shortcomings, we designed a new type of intravenous port which combines the connecting tube into one piece. The aims of this study were to test the mechanical characteristics of the new design and assess its safety in animal study. The prototype of the preattached port was manufactured from biocompatible materials, including PEEK, silicone and polyurethane. All components were assembled with biocompatible glue and mechanical and safety tests were performed to determine the mechanical strength, and tissue reaction of surrounding soft tissue and entry vessels. The mechanical tests showed the new design would not lead to catheter fracture in the oscillation test. The traction test showed significant peak load (18.75 ± 3.29 vs. 26.61 ± 1.75 N; p = 0.036) because of the difference in catheter extension capacity (26.57 ± 4.28 vs. 47.93 ± 2.45 mm; p = 0.012). Significantly smaller endurable injection pressure was identified in the prototype. (90 ± 20 vs. 177.5± 9.48 psi; p = 0.01) The safety test showed good tolerance in beagle dogs and led to no intravascular thrombus and minimal reaction in surrounding tissues. The new prototype preattached port showed good mechanical strength and overcame two potential structural weakness points. The integrated fixation design not only reduced the dimensions of the port device but also provided a greater injection area compared to current designs. It did not cause intravascular thrombosis and produced minimal tissue reaction in surrounding soft tissue, as identified by autopsy. The new design of the fixation device could serve as the basis for the next generation of intravenous ports. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1017-1027, 2018.

Enhanced biocompatibility of neural probes by integrating microstructures and delivering anti-inflammatory agents via microfluidic channels

Objective. Biocompatibility is a major issue for chronic neural implants, involving inflammatory and wound healing responses of neurons and glial cells. To enhance biocompatibility, we developed silicon-parylene hybrid neural probes with open architecture electrodes, microfluidic channels and a reservoir for drug delivery to suppress tissue responses. Approach. We chronically implanted our neural probes in the rat auditory cortex and investigated (1) whether open architecture electrode reduces inflammatory reaction by measuring glial responses; and (2) whether delivery of antibiotic minocycline reduces inflammatory and tissue reaction. Four weeks after implantation, immunostaining for glial fibrillary acid protein (astrocyte marker) and ionizing calcium-binding adaptor molecule 1 (macrophages/microglia cell marker) were conducted to identify immunoreactive astrocyte and microglial cells, and to determine the extent of astrocytes and microglial cell reaction/activation. A comparison was made between using traditional solid-surface electrodes and newly-designed electrodes with open architecture, as well as between deliveries of minocycline and artificial cerebral-spinal fluid diffused through microfluidic channels. Main results. The new probes with integrated micro-structures induced minimal tissue reaction compared to traditional electrodes at 4 weeks after implantation. Microcycline delivered through integrated microfluidic channels reduced tissue response as indicated by decreased microglial reaction around the neural probes implanted. Significance. The new design will help enhance the long-term stability of the implantable devices.

Cell-compatible PHB/silk fibroin composite nanofibermat for tissue engineering applications

Cell compatibility is one of the prominent requirements for the fabrication of tissue engineering materials. Silk fibroin (SF) is an excellent material for biomedical applications and shows desirable properties such as good compatibility, minimal tissue reaction, and tailorable degradability. Poly[(R)-3-hydroxybutyrate] (PHB) has a high percentage of crystallinity and a high melting temperature. In this study, PHB and SF were blended together to improve the mechanical properties of the SF fibrous structure and the crystallinity of PHB. Furthermore, the cell-biomaterial interaction on the PHB/SF composite scaffold was expected to be enhanced via the SF. For this purpose, PHB/SF composite scaffolds were prepared through the use of the electrospinning technique, which is a unique method for the production of biomaterials on the nanoscale intended for tissue engineering. PHB/SF scaffolds were prepared with different SF contents and a suitable electrospinning condition was chosen in terms of structure and fiber diameter. The average fiber diameter was 92 ± 2.6 nm at a flow rate of 0.4 mL/h, distance of 20 cm, polymer concentration of PHB/SF-0 of 7%:18% (w/w) or 1:1 (v/v), and voltage of 20 kV. Mechanical and crystalline properties of the PHB/SF scaffold were investigated. Adhesion and proliferation of L929 and HaCaT (mouse fibroblast and immortalized human keratinocyte cell lines) on PHB/SF-0 were examined.

Prophylactic stenting for esophageal stricture prevention after endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) of superficial esophageal cancer has been increasingly used as an alternative to surgery because it is minimally invasive and has a high rate of en bloc resection. However, a high rate of esophageal stricture is observed after ESD for large lesions, which can dramatically decrease the patient’s quality of life. Stricture prevention is necessary to allow for endoscopic therapy to expand. We, herein, review the most recent evidence and discuss the role of the metallic self-expandable stent and the biodegradable stent in esophageal stricture prevention. Limited studies suggested that prophylactic stenting could reduce the stricture rate without increasing the number of complications. In addition, the number of bougie dilation procedures was significantly lower with stent placement. Esophageal stenting is a promising option for post-ESD stricture prevention. However, current evidence is too preliminary to formulate practice standards. Future studies are needed to further validate the efficacy and safety of prophylactic stenting and determine the best strategy for stricture prevention. Stent migration is the most common complication. A new stent that has advantages of a low migration rate and minimal tissue reaction will need to be developed. Therefore, randomized controlled trials with long-term follow-up periods are required before prophylactic stenting could be considered a valid option to prevent post-ESD stricture.

Anesthetic management of Montgomery T-tube insertion in a child with subglottic stenosis

Montgomery T-tube is made up of silicone which has greater flexibility and minimal tissue reaction. It has the advantage of acting as both tracheostomy tube and stent to keep the tracheal airway open after repair of tracheal stenosis. Here, we report successful management of a case of 10-year-old male child who was tracheostomized for subglottic stenosis which developed due to prolonged mechanical ventilation in Intensive Care Unit due to accidental phenyl consumption.

Evaluation of Different Types of Suture Materials for Midline Abdominal Closure.

The prime purpose of a suture is to hold the wound edges together until it has healed sufficiently to withstand stress and strain on its own.The varieties of sutures are increasing day by day and it is posing an important task before surgeons to select an ideal suture material. The aim of this study is to know which suture material is most reliable for midline abdominal closure In terms of delayed absorption,tensile strength and minimal tissue reaction and at the same time cost effective.The suture materials used in this study are Polyglactin 910 (Vicryl),Pyrrolidine-2-carboxylic acid (Proline),Polyamide (Nylone) and Polydioxanone (PDS).The clinical study was carried out in 180 patients devided into three groups.Group 1 consists of 60 clean and uncontaminated cases.Group 2 consists of 80 contaminated and infected cases.Group 3consists of 40 undernourished and cachectic cases.Each group is devided into four subgroups for each suture materials. Total wound complication rate was different for different suture materials in different groups.On clinical evaluation PDS was foud to be suture of choice in group 1 cases,Whearas Nylone is the suture of choice in group 2 and group 3 cases.

Safety assessment of epidural wire electrodes for cough production in a chronic pig model of spinal cord injury

BackgroundIt is our hypothesis that high intensity spinal cord stimulation (SCS) to restore an effective cough mechanism using wire leads, will result in significant activation of target neurons without tissue injury or electrode corrosion. MethodsAdult mini-pigs underwent chronic spinal cord compression, followed by implantation of parallel wire leads on the dorsal epidural surface of the spinal cord, with stimulation contacts at the T9 and T12, and control electrode contacts at the T2 and T5 levels. After 3 months of daily SCS, airway pressure generation (P), tissue in the area of the stimulating and control electrodes and electrode leads were examined. P was also assessed in acute animals, which served as controls. ResultsMean P at FRC was 54±5cmH2O and 109±11cmH2O in the control and chronically stimulated animals, respectively (p<0.05). There was minimal tissue reaction in the area of the stimulating and control electrodes. All sets of leads revealed no evidence of electrode corrosion. Comparison with existing methodsPrevious porcine models of chronic spinal cord injury (SCI) were developed to study neurological and regenerative outcomes. Our method of chronic SCI porcine model was developed to evaluate the safety of electrical SCS to restore expiratory muscle function. ConclusionChronic SCS with wire lead electrodes results in significant increases in P without evidence of significant adverse tissue reaction, nor evidence of electrode corrosion. This method may be a safe and useful technique to restore a functional cough in spinal cord injured subjects.