Fibrin sealants in surgical practice: An overview

A Phase 3, Randomized, Active-controlled, Single-blind Clinical Trial to Evaluate the Efficacy of Fibrin Sealant Grifols in Achieving Hemostasis in Pediatric Surgery

BACKGROUND

In this study, two fibrin sealant products, Fibrin Sealant Grifols (FS Grifols 80 mg/mL fibrinogen; 500 IU/mL thrombin) and Evicel (fibrinogen 55-85 mg/mL; thrombin 800-1200 IU/mL) were studied for efficacy in achieving hemostasis at a targeted bleeding site (TBS) on parenchymous or soft tissue in pediatric surgeries.

METHODS

This phase 3, single-blind, active comparator, non-inferiority trial compared the number of patients achieving hemostasis at a TBS at four (T4 - primary endpoint), seven (T7) and 10 (T10) minutes after application, Safety and tolerability were assessed by recording adverse events during and after procedures. Eligible patients were <18 years old undergoing elective, open, non-cardiac thoracic, abdominal or pelvic surgeries. Preterm (<37 weeks gestation) and newborn (0-27 days) infants were eligible.

RESULTS

At T4, 98.7% of FS Grifols group (n = 91) and 95.4% of the Evicel group (n = 87) achieved hemostasis. All patients with residual bleeding at T4 were undergoing soft tissue surgery. All patients achieved hemostasis by T7. At T10, all patients achieved hemostasis except one (FS Grifols (no observation recorded)). There were no incidents of persistent bleeding. For FS Grifols, 26.5% of patients had treatment-emergent adverse events (TEAEs) and 18.4% for Evicel. One TEAE (moderate procedural pain - FS Grifols group) was considered possibly related to study treatment. Three patients died for reasons unrelated to the study medications.

CONCLUSIONS

FS Grifols was safe and effective at achieving hemostasis in pediatric patients having parenchymous or soft tissue surgeries. The efficacy of FS Grifols was non-inferior to Evicel.

LEVEL OF EVIDENCE

I.

A Systematic Review of the Efficacy of Haemostatic Interventions in Primary Cleft Palate Repair

OBJECTIVE

To evaluate the effectiveness of adrenaline infiltration, topical adrenaline, systemic tranexamic acid, fibrin tissue sealants and alginate-based topical coagulants at reducing blood loss and post-operative bleeding in primary cleft palate repair.

DESIGN

Systematic review according to PRISMA-P guidelines, using Covidence systematic review software to facilitate 3-stage screening and data extraction by two reviewers.

SETTING

Academic cleft surgery center.

INTERVENTIONS

Any peri-operative intervention to reduce intra-operative and post-operative bleeding.

MAIN OUTCOME MEASURES

Estimated blood loss, rate of post-operative bleeding, rate of return to theatre for haemostasis.

RESULTS

Sixteen relevant studies were identified, with a total of 1469 study participants. Nine studies examined efficacy of infiltrating vasoconstrictors and all concluded that 1:100,000-1:400,000 adrenaline infiltration reduced intra-operative blood loss, to the range of 12-60 ml. Secondary bleeding and re-operation for haemostasis were uncommon. Tranexamic acid was studied in five randomised controlled trials, two of which demonstrated a significant reduction in blood loss compared to a control group. Use of fibrin and gelatin sponge products was examined in 3 studies, all of which reported no or minimal bleeding, but did not have quantifiable outcome measures.

CONCLUSIONS

Infiltration with vasoconstricting agents, administration of systemic tranexamic acid and application of fibrin sealants have a well-studied and favorable safety profile in pediatric cases, and likely contribute to the relatively low incidence of post-operative bleeding and intra-operative blood loss in primary cleft palate repair.

The effectiveness of fibrin sealants in head and neck surgery: a systematic review and meta-analysis

BACKGROUND

Fibrin sealants are increasingly used in head and neck surgery to aid hemostasis, but individual studies lack conclusive evidence. This systematic review investigates their effectiveness compared to placebo or usual care in head and neck surgery.

METHODS

Studies comparing fibrin sealant to placebo or usual care in patients 18 years or older who have undergone soft tissue surgery of the head and neck with drain placement were included. Primary outcomes include wound complications and time to surgical drain removal postoperatively. Secondary outcomes include length of hospital stay, drain volume output, surgical management of hematoma, blood transfusion rates, and adverse reactions. Electronic databases were searched on October 2023 for randomized controlled and quasi-experimental studies. Studies underwent independent screening, review, and appraisal by two reviewers using JBI appraisal tools. Certainty was assessed with GRADE, and meta-analysis was conducted using JBI SUMARI, presenting effect sizes as relative risk ratios or mean differences with 95% confidence intervals.

RESULTS

Fourteen studies were included examining 904 patients. The fibrin sealant group exhibited reduced postoperative wound complications (hematoma, seroma, wound dehiscence, wound infection) (RR = 0.64, 95% CI = 0.45-0.92), shorter drain removal times (MD =  - 0.49 days, 95% CI =  - 0.68 to - 0.29), decreased drain output (MD =  - 16.52 mL, 95% CI =  - 18.56 to - 14.52), and shorter hospital stay (MD =  - 0.84 days, 95% CI =  - 1.11 to - 0.57) compared to controls. There was no statistically significant difference on the rate of intervention for postoperative hematoma and the rate of adverse reactions.

DISCUSSION

Evidence demonstrates with low certainty that fibrin sealant use is associated with a modest reduction in the rate of wound complications, drain duration, and length of stay, and a small reduction in drain volume output. Methodological weaknesses and clinical heterogeneity limit these findings. Further research should focus on enhancing methodological quality and exploring the cost-effectiveness of fibrin sealant use in surgery.

SYSTEMATIC REVIEW REGISTRATION

CRD42023412820.

FUNDING

Nil.

Effectiveness of combined local therapy with antibiotics and fibrin vs. vacuum-assisted wound therapy in soft tissue infections: a retrospective study

PURPOSE

Soft tissue infections can be severe and life-threatening. Their treatment consists currently in radical surgical wound debridement and combined systemic antimicrobial therapy. Different side effects are possible. Local antibiotic therapy represents a new approach to reduce side effects and improve healing. The aim of this study is to assess the effectiveness of the local sprayed use of antibiotics with fibrin sealing compared with negative pressure wound therapy as an established treatment of soft-tissue infections.

METHODS

In this retrospective study, patients with soft tissue infections who underwent surgical treatment were analysed. One group consists of patients, who received local fibrin-antibiotic spray (FAS) (n = 62). Patients treated by vacuum-assisted wound therapy (VAWT) as the established treatment were the control group (n = 57). Main outcomes were differences in the success of healing, the duration until healing and the number of needed operations.

RESULTS

Clinical healing could be achieved for 55 patients (98.21%) in the FAS group vs. 47 patients (92.16%) in the VAWT group (p = 0.19). Time to require this was 10.65 ± 10.38 days in the FAS group and 22.85 ± 14.02 days in the VAWT group (p < 0.001). In the FAS group, patients underwent an average of 1.44 ± 0.72 vs.3.46 ± 1.66 operations in the VAWT group (p < 0.001).

CONCLUSION

Compared to vacuum-assisted wound therapy in soft tissue infections, local fibrin-antibiotic spray shows faster clinical healing and less needed operations. Leading to shorter hospital stays and more satisfied patients. The combination of sprayed fibrin and antibiotics can be seen as a promising and effective method.

Antifibrinolytic and Adjunct Hemostatic Agents: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To derive systematic-review informed, modified Delphi consensus regarding antifibrinolytic and adjunct hemostatic agents in neonates and children supported with extracorporeal membrane oxygenation (ECMO) for the Pediatric ECMO Anticoagulation CollaborativE consensus conference.

DATA SOURCES

A structured literature search was performed using PubMed, EMBASE, and Cochrane Library (CENTRAL) databases from January 1988 to May 2021.

STUDY SELECTION

Use of antifibrinolytics (epsilon-aminocaproic acid [EACA] or tranexamic acid), recombinant factor VII activated (rFVIIa), or topical hemostatic agents (THAs).

DATA EXTRACTION

Two authors reviewed all citations independently, with a third independent reviewer resolving conflicts. Eleven references were used for data extraction and informed recommendations. Evidence tables were constructed using a standardized data extraction form.

MEASUREMENTS AND MAIN RESULTS

Risk of bias was assessed using the Quality in Prognosis Studies tool. The evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation system. Forty-eight experts met over 2 years to develop evidence-based recommendations and, when evidence was lacking, expert-based consensus statements for the management of bleeding and thrombotic complications in pediatric ECMO patients. A web-based modified Delphi process was used to build consensus via the Research And Development/University of California Appropriateness Method. Consensus was defined as greater than 80% agreement. One weak recommendation and three consensus statements are presented.

CONCLUSIONS

Evidence supporting recommendations for administration of antifibrinolytics (EACA or tranexamic acid), rFVIIa, and THAs were sparse and inconclusive. Much work remains to determine effective and safe usage strategies.

Effectiveness of fibrin sealants in head and neck surgery: a systematic review protocol

OBJECTIVE

This review will investigate the effectiveness of fibrin sealants in adult patients who underwent head and neck surgery.

INTRODUCTION

Controlling bleeding is important in head and neck surgery. Complications involving nearby vital structures increase the risk of morbidity and mortality. Surgical tissue adhesives are used in addition to other traditional hemostatic methods to reduce surgical site bleeding. Fibrin sealants have shown some success compared with other tissue adhesives, but individual studies have been inconclusive.

INCLUSION CRITERIA

We will include studies comparing fibrin sealants with placebo or usual care in patients 18 years or older who have undergone soft tissue surgery of the head and neck with drain placement. Primary outcomes include wound complications and time to surgical drain removal. Secondary outcomes include length of hospital stay, drain volume output, surgical management of postoperative hematoma, rate of blood transfusions, and adverse reactions.

METHODS

We will search electronic databases (PubMed, Embase, Cochrane Central Register of Controlled Trials CINAHL, Scopus, Web of Science) for studies published from 1975 onwards. Sources to be search for unpublished literature will include ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, MedNar, and ProQuest Dissertations and Theses. Titles, abstracts, and full-text papers will be assessed against the inclusion criteria by 2 independent reviewers. Study screening and selection will be performed, and critical appraisal conducted using the standardized JBI appraisal tools. Data will be extracted by 2 independent reviewers. Meta-analysis will be conducted for all outcomes where appropriate, with weighted mean differences for continuous data. Risk ratios will be used for dichotomous data. Certainty will be reported using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

REVIEW REGISTRATION

PROSPERO CRD42023412820.

Preparation and In Vitro Characterization of Lactococcus lactis-Loaded Alginate Particles as a Promising Delivery Tool for Periodontal Probiotic Therapy

Probiotic microorganisms are used in a variety of food supplements and medical formulations to promote human health. In periodontal therapy, probiotics are mainly used in the form of gels, tablets or rinses that often tend to leak from the periodontal pocket, resulting in a strongly reduced therapeutic effect. In this pilot in vitro study, we present biodegradable alginate-based particles as an alternative, highly efficient system for a periodontal delivery of probiotic bacteria to the inflammation site. For this purpose, Lactococcus (L.) lactis was encapsulated using a standardized pump-controlled extrusion-dripping method. Time-dependent bacterial release in artificial saliva was investigated over 9 days. The effect of freeze drying was explored to ensure long-term storage of L. lactis-loaded particles. Additionally, the particles were bound to dentin surface using approved bioadhesives and subjected to shear stress in a hydrodynamic flow chamber that mimics the oral cavity in vitro. Thus, round particles within the range of 0.80-1.75 mm in radius could be produced, whereby the diameter of the dripping tip had the most significant impact on the size. Although both small and large particles demonstrated a similar release trend of L. lactis, the release rate was significantly higher in the former. Following lyophilization, particles could restore their original shape within 4 h in artificial saliva; thereby, the bacterial viability was not affected. The attachment strength to dentin intensified by an adhesive could resist forces between 10 and 25 N/m2. Full degradation of the particles was observed after 20 days in artificial saliva. Therefore, alginate particles display a valuable probiotic carrier for periodontal applications that have several crucial advantages over existing preparations: a highly stable form, prolonged continuous release of therapeutic bacteria, precise manufacturing according to required dimensions at the application site, strong attachment to the tooth with low risk of dislocation, high biocompatibility and biodegradability.

Differential efficacy with epidural blood and fibrin patches for the treatment of post-dural puncture headache

BACKGROUND

Accidental dural puncture (ADP) is the most frequent major complication when performing an epidural procedure in obstetrics. Consequently, loss of pressure in the cerebrospinal fluid (CSF) leads to the development of post-dural puncture headache (PDPH), which occurs in 16%-86% of cases. To date, the efficacy of epidural fibrin patches (EFP) has not been evaluated in a controlled clinical trial, nor in comparative studies with epidural blood patches (EBP).

METHODS

The objective of the present study was to compare the efficacy of EFP with respect to EBP for the treatment of refractory accidental PDPH. This prospective, randomized, open-label, parallel, comparative study included 70 puerperal women who received an EBP or EFP (35 in each group) after failure of the conventional analgesic treatment for accidental PDPH in a hospital.

RESULTS

A higher percentage of women with EFP than EBP achieved complete PDPH relief after 2 (97.1% vs. 54.3%) and 12 h (100.0% vs. 65.7%) of the patch injection. The percentage of patients who needed rescue analgesia was significantly lower with EFP after 2 (2.9% vs. 48.6%) and 12 h (0.0% vs. 37.1%). After 24 h, PDPH was resolved in all women who received EFP. The recurrence of PDPH was reported in one woman from the EBP group (2.9%), who subsequently required a second patch. The mean length of hospital stay was significantly lower with EFP (3.9 days) than EBP (5.9 days). Regarding satisfaction, the mean value (Likert scale) was significantly higher with EFP (4.7 vs. 3.0).

CONCLUSIONS

EFP provided better outcomes than EBP for the treatment of obstetric PDPH in terms of efficacy, safety, and patient satisfaction.

Thrombin and Thrombin-Incorporated Biomaterials for Disease Treatments

Thrombin, a coagulation-inducing protease, has long been used in the hemostatic field. During the past decades, many other therapeutic uses of thrombin have been developed. For instance, burn treatment, pseudoaneurysm therapy, wound management, and tumor vascular infarction (or tumor vasculature blockade therapy) can all utilize the unique and powerful function of thrombin. Based on their therapeutic effects, many thrombin-associated products have been certificated by the Food and Drug Administration, including bovine thrombin, human thrombin, recombinant thrombin, fibrin glue, etc. Besides, several thrombin-based drugs are currently undergoing clinical trials. In this article, the therapeutic uses of thrombin (from the initial hemostasis to the latest cancer therapy), the commercially available drugs associated with thrombin, and the pros and cons of thrombin-based therapeutics (e.g., adverse immune responses related to bovine thrombin, thromboinflammation, and vasculogenic "rebounds") are summarized. Further, the current challenges and possible future research directions of thrombin-incorporated biomaterials and therapies are discussed. It is hoped that this review may provide a valuable reference for researchers in this field and help them to design safer and more effective thrombin-based drugs for fighting against various intractable diseases.

Underwater Adhesives from Redox-Responsive Polyplexes of Thiolated Polyamide Polyelectrolytes

We report the fabrication of optically clear underwater adhesives using polyplexes of oppositely charged partially-thiolated polyamide polyelectrolytes (TPEs). The thiol content of the constituent PEs was varied to assess its influence on the adhesive properties of the resulting glues. These catechol-free, redox-responsive TPE-adhesives were formulated in aquo and exhibited high optical transparency and strong adhesion even on submerged or moist surfaces of diverse polar substrates such as glass, aluminium, wood, and bone pieces. The adhesives could be cured under water through oxidative disulphide crosslinking of the constituent TPEs. The polyamide backbone provided multi-site H-bonding interactions with the substrates while the disulphide crosslinking provided the cohesive strength to the glue. Strong adhesion of mammalian bones (load bearing capacity upto 7 kg/cm2 ) was achieved using the adhesive containing 30 mol % thiol residues. Higher pH and use of oxidants such as povidone-iodine solution enhanced the curing rate of the adhesives, and so did the use of Tris buffer instead of Phosphate buffer. The porous architecture of the adhesive and its progressive degradation in aqueous medium over the course of three weeks bode well for diverse biomedical applications where temporary adhesion of tissues is required.

Endoscopic Intervention for Anastomotic Leakage After Gastrectomy

Anastomotic leaks and fistulas are significant complications of gastric surgery that potentially lead to increased postoperative morbidity and mortality. Surgical intervention is reserved for cases with severe symptoms or hemodynamic instability; however, surgery carries a higher risk of complications. With advancements in endoscopic treatment options, endoscopic approaches have emerged as the primary choice for managing these complications. Endoscopic clipping is a traditional method comprising 2 main categories: through-the-scope clips and over-the-scope clips. Through-the-scope clips are user friendly and adaptable to various clinical scenarios, whereas over-the-scope clips can close larger defects. Another promising approach is endoscopic stent insertion, which has shown a high success rate for leak closure, although vigilant monitoring is required to monitor stent migration. Infection control is essential in post-surgical leakage cases, and endoscopic internal drainage provides a relatively safe and noninvasive means to manage fluids, contributing to infection control and wound healing promotion. Endoscopic suturing offers full-thickness wound closure, but requires additional training and endoscopic versatility. As a promising tool, endoscopic vacuum therapy potentially surpasses stent therapy by draining inflammatory materials and closing defects. Furthermore, the use of tissue sealants, such as fibrin glue and cyanoacrylate, has been reported to be effective in selected situations. The choice of endoscopic device should be tailored to individual cases and specific patient conditions, with careful consideration of the nature of the defect. Further extensive studies involving larger patient populations are required to provide more robust evidence on the efficacy of endoscopic approach in managing post-gastric anastomotic leaks.

Bioadhesive Technology Platforms

Bioadhesives have emerged as transformative and versatile tools in healthcare, offering the ability to attach tissues with ease and minimal damage. These materials present numerous opportunities for tissue repair and biomedical device integration, creating a broad landscape of applications that have captivated clinical and scientific interest alike. However, fully unlocking their potential requires multifaceted design strategies involving optimal adhesion, suitable biological interactions, and efficient signal communication. In this Review, we delve into these pivotal aspects of bioadhesive design, highlight the latest advances in their biomedical applications, and identify potential opportunities that lie ahead for bioadhesives as multifunctional technology platforms.

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.

Biological Materials for Tissue-Engineered Vascular Grafts: Overview of Recent Advancements

The clinical demand for tissue-engineered vascular grafts is still rising, and there are many challenges that need to be overcome, in particular, to obtain functional small-diameter grafts. The many advances made in cell culture, biomaterials, manufacturing techniques, and tissue engineering methods have led to various promising solutions for vascular graft production, with available options able to recapitulate both biological and mechanical properties of native blood vessels. Due to the rising interest in materials with bioactive potentials, materials from natural sources have also recently gained more attention for vascular tissue engineering, and new strategies have been developed to solve the disadvantages related to their use. In this review, the progress made in tissue-engineered vascular graft production is discussed. We highlight, in particular, the use of natural materials as scaffolds for vascular tissue engineering.

The Evolving Role of Proteins in Wearable Sweat Biosensors

Sweat is an increasingly popular biological medium for fitness monitoring and clinical diagnostics. It contains an abundance of biological information and is available continuously and noninvasively. Sweat-sensing devices often employ proteins in various capacities to create skin-friendly matrices that accurately extract valuable and time-sensitive information from sweat. Proteins were first used in sensors as biorecognition elements in the form of enzymes and antibodies, which are now being tuned to operate at ranges relevant for sweat. In addition, a range of structural proteins, sometimes assembled in conjunction with polymers, can provide flexible and compatible matrices for skin sensors. Other proteins also naturally possess a range of functionalities─as adhesives, charge conductors, fluorescence emitters, and power generators─that can make them useful components in wearable devices. Here, we examine the four main components of wearable sweat sensors─the biorecognition element, the transducer, the scaffold, and the adhesive─and the roles that proteins have played so far, or promise to play in the future, in each component. On a case-by-case basis, we analyze the performance characteristics of existing protein-based devices, their applicable ranges of detection, their transduction mechanism and their mechanical properties. Thereby, we review and compare proteins that can readily be used in sweat sensors and others that will require further efforts to overcome design, stability or scalability challenges. Incorporating proteins in one or multiple components of sweat sensors could lead to the development and deployment of tunable, greener, and safer biosourced devices.

A comparative high-resolution physicochemical analysis of commercially available fibrin sealants: Impact of sealant osmolality on biological performance

Fibrin sealants are well-established components of the surgical toolbox, especially in procedures that harbor a high risk of perioperative bleeding. Their widespread use as hemostats, sealants or tissue-adhesives in various surgical settings has shown that the choice of the appropriate sealant system affects the clinical outcome. While many studies have compared the hemostatic efficiency of fibrin sealants to that of other natural or synthetic sealants, there is still limited data on how subtle differences in fibrin sealant formulations relate to their biological performance. Here, we performed an in-depth physicochemical and biological characterization of the two most commonly used fibrin sealants in the US and Europe: TISSEEL™ ("FS") and VISTASEAL™/VERASEAL™ ("FS+Osm"). Our chemical analyses demonstrated differences between the two sealants, with lower fibrinogen concentrations and supraphysiological osmolality in the FS+Osm formulation. Rheological testing revealed FS clots have greater clot stiffness, which strongly correlated with network density. Ultrastructural analysis by scanning electron microscopy revealed differences between FS and FS+Osm fibrin networks, the latter characterized by a largely amorphous hydrogel structure in contrast to the physiological fibrillar network of FS. Cytocompatibility experiments with human fibroblasts seeded on FS and FS+Osm fibrin networks, or cultured in presence of sealant extracts, revealed that FS+Osm induced apoptosis, which was not observed with FS. Although differential sealant osmolality and amounts of fibrinogen, as well as the presence of Factor XIII or additives such as antifibrinolytics, may explain the mechanical and structural differences observed between the two fibrin sealants, none of these substances are known to cause apoptosis at the respective concentrations in the sealant formulation. We thus conclude that hyper osmolality in the FS+Osm formulation is the primary trigger of apoptosis-a mechanism that should be evaluated in more detail, as it may affect the cellular wound healing response in situ.

Postoperative Intratumoral or Peritumoral Hematomas After Vestibular Schwannoma Resection

BACKGROUND

Surgical removal of a vestibular schwannoma is a complex and challenging procedure, which may be complicated by development of postoperative hematomas, particularly after incomplete resection of the tumor.

OBJECTIVE

To investigate the occurrence of postoperative intra- or peritumoral hematomas after surgery for a vestibular schwannoma.

METHODS

This retrospective study evaluated 49 patients (age range 17-78 years) with a vestibular schwannoma, who were treated surgically via the lateral suboccipital approach between 2011 and 2016. The tumors ranged in size from 0 mm (in a case of an intracanalicular lesion) to 56 mm. In 30 cases (61%), total or near-total resection was accomplished, and in 19 cases (39%), subtotal or partial resection was done. On the basis of their bleeding tendency during tumor removal, the patients were divided into a "less-bleeding" (38 cases; 78%) and a "more-bleeding" (11 cases; 22%) subgroups.

RESULTS

A maximal vestibular schwannoma diameter >30 mm, patient age >60 years, and more bleeding during tumor removal were significantly associated with incomplete (subtotal or partial) resection. In six cases (12%), serial computed tomography after surgery demonstrated a postoperative hematoma, which was caused by insufficient irrigation of the surgical field (in two cases) or resulted from peritumoral hemorrhage (in two cases), intratumoral hemorrhage (in one case), or both intra- and peritumoral hemorrhage (in one case). The latter patient required urgent reoperation. In all cases, postoperative hematomas occurred after incomplete (subtotal or partial) resection of a vestibular schwannoma, and their development was significantly associated with more bleeding during tumor removal.

CONCLUSION

For avoidance of postoperative hematomas, careful hemostasis is required after completion of vestibular schwannoma removal, especially in cases with incomplete resection and an excessive bleeding tendency of the tumor tissue.

Technological advances in fibrin for tissue engineering

Fibrin is a promising natural polymer that is widely used for diverse applications, such as hemostatic glue, carrier for drug and cell delivery, and matrix for tissue engineering. Despite the significant advances in the use of fibrin for bioengineering and biomedical applications, some of its characteristics must be improved for suitability for general use. For example, fibrin hydrogels tend to shrink and degrade quickly after polymerization, particularly when they contain embedded cells. In addition, their poor mechanical properties and batch-to-batch variability affect their handling, long-term stability, standardization, and reliability. One of the most widely used approaches to improve their properties has been modification of the structure and composition of fibrin hydrogels. In this review, recent advances in composite fibrin scaffolds, chemically modified fibrin hydrogels, interpenetrated polymer network (IPN) hydrogels composed of fibrin and other synthetic or natural polymers are critically reviewed, focusing on their use for tissue engineering.

Advances in Fibrin-Based Materials in Wound Repair: A Review

The first bioprocess that occurs in response to wounding is the deterrence of local hemorrhage. This is accomplished by platelet aggregation and initiation of the hemostasis cascade. The resulting blood clot immediately enables the cessation of bleeding and then functions as a provisional matrix for wound healing, which begins a few days after injury. Here, fibrinogen and fibrin fibers are the key players, because they literally serve as scaffolds for tissue regeneration and promote the migration of cells, as well as the ingrowth of tissues. Fibrin is also an important modulator of healing and a host defense system against microbes that effectively maintains incoming leukocytes and acts as reservoir for growth factors. This review presents recent advances in the understanding and applications of fibrin and fibrin-fiber-incorporated biomedical materials applied to wound healing and subsequent tissue repair. It also discusses how fibrin-based materials function through several wound healing stages including physical barrier formation, the entrapment of bacteria, drug and cell delivery, and eventual degradation. Pure fibrin is not mechanically strong and stable enough to act as a singular wound repair material. To alleviate this problem, this paper will demonstrate recent advances in the modification of fibrin with next-generation materials exhibiting enhanced stability and medical efficacy, along with a detailed look at the mechanical properties of fibrin and fibrin-laden materials. Specifically, fibrin-based nanocomposites and their role in wound repair, sustained drug release, cell delivery to wound sites, skin reconstruction, and biomedical applications of drug-loaded fibrin-based materials will be demonstrated and discussed.

Therapeutic use of α2-antiplasmin as an antifibrinolytic and hemostatic agent in surgery and regenerative medicine

The biomaterial fibrin is widely used as a clinical tissue sealant in surgery. In preclinical research, fibrin is also extensively studied as a carrier material for growth factor delivery. In these applications, premature fibrin degradation leads to recurrent bleeding, tissue dehiscence and limited regenerative efficacy. Therefore, fibrinolysis inhibitors have been added to clinical fibrin formulations, for example the bovine-derived serine protease inhibitor aprotinin. Aprotinin is additionally used as a hemostatic agent to prevent excessive bleeding during surgery, in this case protecting endogenous fibrin clots. Nevertheless, aprotinin use has been associated with serious safety issues. Here, we explore the use the human physiological fibrinolysis inhibitor α2-antiplasmin (α2PI) as a substitute for aprotinin. We evaluate the efficacy of α2PI in the three main applications of aprotinin. We first showed that recombinant α2PI can successfully prolong the durability of fibrin biomaterials as compared to aprotinin in a model of subcutaneous implantation in mice mimicking application as a tissue sealant. We then used α2PI to enhance the delivery of engineered vascular endothelial growth factor (VEGF)-A and platelet-derived growth factor (PDGF)-BB in fibrin in promoting diabetic wound healing, which lead to improved wound closure, granulation tissue formation and angiogenesis. Lastly, we demonstrated that α2PI can be as effective as aprotinin as an intravenous hemostatic agent to prevent blood loss, using a tail-vein bleeding model in mice. Therefore, we believe that engineering fibrin biomaterials or endogenous fibrin with α2PI can have a strong impact in surgery and regenerative medicine by providing a competitive substitute to aprotinin that is of human origin.

Photo-crosslinked Antimicrobial Hydrogel Exhibiting Wound Healing Ability and Curing Infections In-vivo

With the increasing focus on healthcare research in the current times, therapeutic and biomaterial interventions for healing of wounds and mitigation of wound-associated infections have seen expedited progress. Conventional approaches consist of release-active gels, which demonstrate leaching of antimicrobials, such as antibiotics, metal ions, etc. However, these systems suffer from the disadvantages of burst release, reservoir exhaustion, and associated toxicity. In this report, we have developed the intrinsically antimicrobial hydrogel (HyDex) by one-pot UV crosslinking of methacrylated dextran (Dex-MA), polyethylene glycol diacrylate (PEG-DA), and cationic lipophilic methacrylate (LipMA) with varied hydrophobic chain which displays broad-spectrum antimicrobial activity, hemostatic ability, and rapid wound closure efficacy. Optimized hydrogel exhibited potent antimicrobial efficacy against multi-drug resistant Gram-positive and Gram-negative bacteria as well as against pathogenic fungus Candida albicans. HyDex hydrogel showed rapid arrest of bleeding in mice liver puncture model. The hydrogel killed carbapenem-resistant Acinetobacter baumannii in a murine model of burn wound infection with >99% reduction in bacterial burden. Furthermore, this hydrogel displayed significant reduction in inflammatory responses, with accelerated wound healing in rat deep wound model. Collectively, these results implied the excellent promise held by lead hydrogel to be developed for tackling deep tissue wounds, notorious infections, and resulting inflammatory responses. This article is protected by copyright. All rights reserved.

Engineered Molecular Therapeutics Targeting Fibrin and the Coagulation System: a Biophysical Perspective

The coagulation cascade represents a sophisticated and highly choreographed series of molecular events taking place in the blood with important clinical implications. One key player in coagulation is fibrinogen, a highly abundant soluble blood protein that is processed by thrombin proteases at wound sites, triggering self-assembly of an insoluble protein hydrogel known as a fibrin clot. By forming the key protein component of blood clots, fibrin acts as a structural biomaterial with biophysical properties well suited to its role inhibiting fluid flow and maintaining hemostasis. Based on its clinical importance, fibrin is being investigated as a potentially valuable molecular target in the development of coagulation therapies. In this topical review, we summarize our current understanding of the coagulation cascade from a molecular, structural and biophysical perspective. We highlight single-molecule studies on proteins involved in blood coagulation and report on the current state of the art in directed evolution and molecular engineering of fibrin-targeted proteins and polymers for modulating coagulation. This biophysical overview will help acclimatize newcomers to the field and catalyze interdisciplinary work in biomolecular engineering toward the development of new therapies targeting fibrin and the coagulation system.

Local Fixation of Colistin With Fibrin Spray: An in vivo Animal Study for the Therapy of Skin and Soft Tissue Infections

Objective

Skin and soft tissue infections (SSTI) are a commonly known entity of diseases associated with difficult treatment procedures. The current gold standard when there is a rapidly progressing infection of soft tissues with a risk of sepsis is radical surgical debridement accompanied by systemic antibiotic therapy. In clinical settings, local antibiotics alone or formulated within carrier material are commonly used alongside this therapy regimen. One possibility of local antibiotic application is the fixation of colistin with fibrin glue spray. It is not yet sufficiently researched how the local antibiotic concentrations remain as high as possible over time.

Methods

We conducted an animal study including 29 male Wistar rats inducing sterile back sores reaching the muscle fascia. We sprayed only colistin, simultaneously or consecutively, with fibrin glue in different groups in order to measure the tissue concentration of the antibiotic applied locally.

Results

After liquid chromatography and quadrupole mass spectrometry analysis, it could be demonstrated that in comparison to the colistin group, tissue concentrations of colistin stayed significantly higher in the wound tissue when it was fixed with fibrin glue. This was observed in both groups, the simultaneous as well as in the consecutively fibrin glue sprayed groups after colistin application.

Conclusion

The fixation of colistin with the fibrin-glue-spray technique as a carrier for local antibiotic therapy is an easy and inexpensive method and shows promising potential for the treatment of SSTI.

Plasma Bead Entrapped Liposomes as a Potential Drug Delivery System to Combat Fungal Infections

Fibrin-based systems offer promises in drug and gene delivery as well as tissue engineering. We established earlier a fibrin-based plasma beads (PB) system as an efficient carrier of drugs and antigens. In the present work, attempts were made to further improve its therapeutic efficacy exploiting innovative ideas, including the use of plasma alginate composite matrices, proteolytic inhibitors, cross linkers, and dual entrapment in various liposomal formulations. In vitro efficacy of the different formulations was examined. Pharmacokinetics of the formulations encapsulating Amphotericin B (AmpB), an antifungal compound, were investigated in Swiss albino mice. While administration of the free AmpB led to its rapid elimination (<72 h), PB/liposome-PB systems were significantly effective in sustaining AmpB release in the circulation (>144 h) and its gradual accumulation in the vital organs, also compared to the liposomal formulations alone. Interestingly, the slow release of AmpB from PB was unusual compared to other small molecules in our earlier findings, suggesting strong interaction with plasma proteins. Molecular interaction studies of bovine serum albumin constituting approximately 60% of plasma with AmpB using isothermal titration calorimetry and in silico docking verify these interactions, explaining the slow release of AmpB entrapped in PB alone. The above findings suggest that PB/liposome-PB could be used as safe and effective delivery systems to combat fungal infections in humans.

Engineering a naturally derived hemostatic sealant for sealing internal organs

Controlling bleeding from a raptured tissue, especially during the surgeries, is essentially important. Particularly for soft and dynamic internal organs where use of sutures, staples, or wires is limited, treatments with hemostatic adhesives have proven to be beneficial. However, major drawbacks with clinically used hemostats include lack of adhesion to wet tissue and poor mechanics. In view of these, herein, we engineered a double-crosslinked sealant which showed excellent hemostasis (comparable to existing commercial hemostat) without compromising its wet tissue adhesion. Mechanistically, the engineered hydrogel controlled the bleeding through its wound-sealing capability and inherent chemical activity. This mussel-inspired hemostatic adhesive hydrogel, named gelatin methacryloyl-catechol (GelMAC), contained covalently functionalized catechol and methacrylate moieties and showed excellent biocompatibility both in vitro and in vivo. Hemostatic property of GelMAC hydrogel was initially demonstrated with an in vitro blood clotting assay, which showed significantly reduced clotting time compared to the clinically used hemostat, Surgicel®. This was further assessed with an in vivo liver bleeding test in rats where GelMAC hydrogel closed the incision rapidly and initiated blood coagulation even faster than Surgicel®. The engineered GelMAC hydrogel-based seaalant with excellent hemostatic property and tissue adhesion can be utilized for controlling bleeding and sealing of soft internal organs.

More than just a urinary catheter: achieving hemostasis using Foley catheter in deep cerebral cavities—technical nuances

Background

Achieving hemostasis during neurosurgical procedures within deep seated tumors is of paramount importance. Chemical methods like using ORC and gel foam are preferred to bipolar cautery as bipolar cautery causes thermal injury to the normal eloquent surrounding white matter fibers, thereby causing significant morbidities. In addition to the chemical methods, we advocate a new relatively simple mechanical method by using small size Foley catheter inflated with saline can achieve hemostasis in case of deep locating brain tumor surgery with diffuse oozing from the tumor bed and surrounding white matter tissues are of concern. The balloon tamponade effect of the inflated Foley catheter helps in achieving complete hemostasis without damaging the surrounding normal white matter parenchyma.

Case presentation

A 52-years-old female admitted with history of progressive drowsiness and altered sensorium. Brain MRI was done showing large right-sided trigonal meningioma. Right parieto-occipital craniotomy was done, through the superior parietal lobe, corticotomy was done, and tumor was reached. Gentle retraction was done using curved blades in between the tumor and normal brain parenchyma. During surgery, following tumor removal, there was a diffuse oozing from tumor bed and the surrounding stretched white matter fibers. Hemostasis was attempted with chemical methods like ORC and gel foam. We avoided bipolar cautery to prevent thermal injury to the normal stretched eloquent white matter, as bleeding was not settled over the period of 45 min using chemical methods. Then, we placed a 10 F size Foley catheter in the tumor cavity and inflated with 6 ml of saline over the period of 10 min. Prior to Foley placement, we coated ORC over the tumor bed and the surrounding white matter. This achieved hemostasis to a significant extent and the same was repeated for another 10 min, and finally, complete hemostasis was achieved. Postoperative period went uneventful. Patient was discharged with good neurological recovery.

Conclusion

Inflatable Foley catheter balloon is a simple, cost-effective technique for achieving hemostasis in deep white matter tumors in addition to the routinely available hemostatic techniques.

Safety and efficacy of sFilm-FS, a novel biodegradable fibrin sealant, in Göttingen minipigs

Bleeding during surgical procedures is a common complication. Therefore, hemostatic agents have been developed to control bleeding, and fibrin sealants have several benefits. sFilm-FS is a novel fibrin sealant that comprises a biodegradable co-polymeric film embedded with human fibrinogen and thrombin. Herein, the safety and efficacy of sFilm-FS were compared using a liver and spleen puncture model of Göttingen minipigs with those of the standard hemostatic techniques (control animals) and EVARREST^®, a reference fibrin sealant. Hemostasis and reduced blood loss were more effectively achieved with sFilm-FS than with the standard techniques in the control animals and comparable to those achieved with EVARREST^®. No treatment-related adverse effects were observed in any of the groups. Histopathological evaluation indicated that sFilm-FS was slightly and moderately reactive at the liver puncture site and spleen, respectively, compared with the standard techniques in the control animals. These changes are expected degradation reactions of the co-polymeric film and are not considered as adverse events. No treatment-related abnormalities were noted in the other evaluated organs. Additionally, no evidence of local or systemic thromboses was noted. These results support the use of sFilm-FS for hemostasis in humans.

A Systematic Review of Fibrin Glue as an Ideal Treatment for the Pilonidal Disease

Pilonidal sinus is an acquired condition caused by irritation to the hair follicles at the natal cleft, presenting with an abscess or chronic infection. It is prevalent in young adults affecting their productive lifestyle with morbidities. There are varieties of treatment options; however, there is no consensus yet for the ideal procedure. Less invasive procedures have evolved to replace the traditional surgical techniques, which cannot significantly reduce the risks of recurrence and wound complications despite extensive surgeries. We aimed to assess the effect of fibrin glue as a primary treatment after cleaning the sinus in pilonidal sinus disease. We searched for articles from PubMed®, Ovid MEDLINE®, Ovid EMBASE®, and Cochrane CENTRAL. Six studies that included 336 patients in total were analyzed. Fibrin glue treatment in these studies reported a quicker return to normal activities postoperatively, a low rate of infection, and an acceptable rate of recurrence. Thus, fibrin glue seems beneficial in the management of pilonidal disease. However, further high-quality studies are essential to support and confirm this evidence. Future research should also evaluate its cost and implications in the ambulatory service.

Novel autologous, high concentrated fibrin as advanced hemostatic agent for coronary surgery

BACKGROUND

Variability in transfusion outcomes and excessive postoperative bleeding represents a significant problem in cardiac surgery. The effort to reduce bleeding complications and transfusion outcomes is desirable. Our study investigated the feasibility of reducing bleeding complications and transfusion requirements by applying perioperatively prepared autologous bio-regenerative fibrin sealant.

METHODS

A prospective, case-control study enrolled 74 patients undergoing coronary artery bypass grafting by a single surgeon. Patients in the control group (N = 43), received traditional methods of hemostasis, while patients in the experimental group (N = 31) were treated additionally with autologous bio-regenerative fibrin.

RESULTS

Patients were well-matched with regard to basic demographic, laboratory and procedural data. Allogeneic blood transfusion requirement in control group was 39.5 % (17 of 43 patients), compared to 6.5 % (2 of 31 patients) in treated group (p < 0,001). The lower infection rate in the experimental group was also noted. No safety issues were identified during the preparation and application process.

CONCLUSION

Autologous bio-regenerative fibrin can be safely prepared, with no time consuming, and was demonstrated to be a useful tool to decrease allogeneic blood transfusion requirements following elective coronary artery bypass grafting surgery. A prospective randomized trial is needed to confirm these findings.

Ex Vivo Comparison of a UV-Polymerizable Methacrylate Adhesive versus an Inverting Pattern as the Second Layer of a Two-Layer Hand-Sewn Jejunal Anastomosis in Horses: A Pilot Study

Resection and anastomosis of small intestine during colic can lead to adhesions and recurrent colic. Several methods are available to reduce the rate of adhesions in the postoperative period, such as the use of serosal barriers. Surgical glues form a smooth surface, are fast to apply, and could reduce surgery time when performing anastomosis. A recently developed UV-polymerizable methacrylate adhesive (UV-PMA) is designed to anchor into the biological tissues' top surface offering sealant and a smooth cover over the anastomosis site. This adhesive was used ex vivo on fifteen samples of equine jejunum as the second layer of a two-layer anastomosis (1L-UV-PMA group) and compared to a two-layer anastomosis (simple continuous pattern covered with a Cushing pattern; 2L-CT group), in terms of feasibility, bursting strength pressure (BSP), luminal diameter reduction (LDR), and time of construction. Data were analysed using a paired t-test or a chi²-test (P < 0.05). The results showed no statistical difference in BSP, LDR, or any mode of failure between the two anastomosis types. However, the glue anastomosis formed a tunnel-like anastomosis and shredded under pressure, before apparition of leakage, preventing its usage in clinical cases with this methodology. It was concluded that modification of the technique is warranted before testing in clinical cases. A preprint of a former version of the manuscript is available on researchsquare.com, which was not conducted to print and publication after peer reviewing. Since then, the manuscript has been modified to this current version.

Effectiveness of Repair Techniques for Spinal Dural Tears: A Systematic Review

BACKGROUND

Incidental or intentional durotomy in spine surgery is associated with a risk of cerebrospinal fluid (CSF) leakage and reoperation. Several strategies have been introduced, but the incomplete closure is still relatively frequent and troublesome. In this study, we review current evidence on spinal dural repair strategies and evaluate their efficacy.

METHODS

PubMed, Web of Science, and Scopus were used to search primary studies about the repair of the spinal dura with different techniques. Of 265 articles found, 11 studies, which specified repair techniques and postoperative outcomes, were included for qualitative and quantitative analysis. The primary outcomes were CSF leakage and postoperative infection.

RESULTS

The outcomes of different dural repair techniques were available in 776 cases. Pooled analysis of 11 studies demonstrated that the most commonly used technique was a combination of primary closure, patch or graft, and sealant (22.7%, 176/776). A combination of primary closure and patch or graft resulted in the lowest rate of CSF leakage (5.5%, 7/128). In this study, sealants as an adjunct to primary closure (13.7%, 18/131) did not significantly reduce the rate of CSF leakage compared with primary closure alone (17.6%, 18/102). The rates of infection and postoperative neurologic deficit were similar regardless of the repair techniques.

CONCLUSIONS

Although the use of sealants has become prevalent, available sealants as an adjunct to primary closure did not reduce the rate of CSF leakage compared with primary closure. The combination of primary closure and patches or grafts could be effective in decreasing postoperative CSF leakage.

Evaluation of cell viability of Human Dental Pulp Stem Cells in Two dimensional and Three dimensional Fibrin Glue Scaffold

Context:

Regenerative endodontics uses the concept of tissue engineering to restore the diseased immature tooth, allowing for continued development of the root to a healthy state. For regenerative endodontics, the use of human dental pulp stem cells (HDPSCs) with appropriate scaffolds and growth factors is imperative.

Aims:

The aim of the study was to evaluate the human dental pulp cell viability in two-dimensional (2D) and 3D fibrin glue scaffold to be used in regenerative endodontics.

Subjects and Methods:

Regenerative potential of HDPSCs was comparatively assessed usings 2D and 3D fibrin glue scaffold. 3D scaffold was made with different concentrations of fibrinogen. Cell morphology was studied under inverted phase-contrast microscopy, and cell proliferation was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay at various time intervals.

Statistical Analysis Used:

Collected data underwent a two-way ANOVA test. The P value of the study was kept 0.05 according to the sample size.

Results:

Study revealed a significant increase in the proliferation of HDPSCs in fibrin glue precoated wells of 2D fibrin glue compared to preseeded cells on day 1 and day 3. The concentration of fibrinogen has a major role in cell viability in 3D fibrin glue scaffold. Homing of HDPSCs in the 3D scaffold improves with time.

Conclusions:

This study concludes that the concentration of fibrin glue has a significant role in HDPSC Viability in 3D scaffold.

Fibrin-Based Biomaterial Systems to Enhance Anterior Cruciate Ligament Healing

Anterior cruciate ligament (ACL) tears are a common and potentially career-ending injury, particularly for athletes and soldiers. Partial and complete ruptures of this ligament cause instability in the knee, and the ACL does not have the capacity for healing due, in part, to its position within the highly thrombolytic synovial fluid environment of the knee joint. Traditional methods of ACL reconstruction, such as graft replacement with attached bone anchors for bone integration, restore stability, but do not prevent the development of post-traumatic osteoarthritis. To enhance therapeutic treatment options, novel fibrin-based technologies and repair techniques have been recently explored and show promise for improved patient outcomes. Through modification of existing surgical methods, such as the use of fibrin glues incorporating growth factors and cells and the implementation of scaffolds containing platelet-rich plasma, platelet-rich fibrin, and other blood derivatives, surgeons are attempting to overcome the shortcomings of traditional treatments. This mini-review will detail current efforts using fibrin-based treatments and discuss opportunities to further enhance ACL healing.

Transparent PDMS Bioreactors for the Fabrication and Analysis of Multi-Layer Pre-vascularized Hydrogels Under Continuous Perfusion

Tissue engineering in combination with stem cell technology has the potential to revolutionize human healthcare. It aims at the generation of artificial tissues that can mimic the original with complex functions for medical applications. However, even the best current designs are limited in size, if the transport of nutrients and oxygen to the cells and the removal of cellular metabolites waste is mainly dependent on passive diffusion. Incorporation of functional biomimetic vasculature within tissue engineered constructs can overcome this shortcoming. Here, we developed a novel strategy using 3D printing and injection molding technology to customize multilayer hydrogel constructs with pre-vascularized structures in transparent Polydimethysiloxane (PDMS) bioreactors. These bioreactors can be directly connected to continuous perfusion systems without complicated construct assembling. Mimicking natural layer-structures of vascular walls, multilayer vessel constructs were fabricated with cell-laden fibrin and collagen gels, respectively. The multilayer design allows functional organization of multiple cell types, i.e., mesenchymal stem cells (MSCs) in outer layer, human umbilical vein endothelial cells (HUVECs) the inner layer and smooth muscle cells in between MSCs and HUVECs layers. Multiplex layers with different cell types showed clear boundaries and growth along the hydrogel layers. This work demonstrates a rapid, cost-effective, and practical method to fabricate customized 3D-multilayer vascular models. It allows precise design of parameters like length, thickness, diameter of lumens and the whole vessel constructs resembling the natural tissue in detail without the need of sophisticated skills or equipment. The ready-to-use bioreactor with hydrogel constructs could be used for biomedical applications including pre-vascularization for transplantable engineered tissue or studies of vascular biology.

Perioperative Blood Management Strategies for Patients Undergoing Total Hip Arthroplasty: Where Do We Currently Stand on This Matter?

Total hip replacement (THR) has proved to be a reliable treatment for the end stage of hip osteoarthritis. It is a common orthopaedic procedure with excellent results, but is associated with significant blood loss and high rates of allogeneic blood transfusion (ABT). The potential complications and adverse events after ABT, combined with the ongoing research, have resulted in multimodel, multidisciplinary blood management strategies adoption, aiming to reduce the blood loss and transfusion rates. Many reviews and meta-analyses have tried to demonstrate the best blood management strategies. The purpose of this study is to review any evidence-based blood conserving technique, dividing them in three stages: preoperative, intraoperative and postoperative.

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.

Neonatal Fibrin Scaffolds Promote Enhanced Cell Adhesion, Migration, and Wound Healing In Vivo Compared to Adult Fibrin Scaffolds

INTRODUCTION

Fibrin scaffolds are often utilized to treat chronic wounds. The monomer fibrinogen used to create such scaffolds is typically derived from adult human or porcine plasma. However, our previous studies have identified extensive differences in fibrin network properties between adults and neonates, including higher fiber alignment in neonatal networks. Wound healing outcomes have been linked to fibrin matrix structure, including fiber alignment, which can affect the binding and migration of cells. We hypothesized that fibrin scaffolds derived from neonatal fibrin would enhance wound healing outcomes compared to adult fibrin scaffolds.

METHODS

Fibrin scaffolds were formed from purified adult or neonatal fibrinogen and thrombin then structural analysis was conducted via confocal microscopy. Human neonatal dermal fibroblast attachment, migration, and morphology on fibrin scaffolds were assessed. A murine full thickness injury model was used to compare healing in vivo in the presence of neonatal fibrin, adult fibrin, or saline.

RESULTS

Distinct fibrin architectures were observed between adult and neonatal scaffolds. Significantly higher fibroblast attachment and migration was observed on neonatal scaffolds compared to adults. Cell morphology on neonatal scaffolds exhibited higher spreading compared to adult scaffolds. In vivo significantly smaller wound areas and greater epidermal thickness were observed when wounds were treated with neonatal fibrin compared to adult fibrin or a saline control.

CONCLUSIONS

Distinctions in neonatal and adult fibrin scaffold properties influence cellular behavior and wound healing. These studies indicate that fibrin scaffolds sourced from neonatal plasma could improve healing outcomes compared to scaffolds sourced from adult plasma.

Refractory Congenital Chylous Ascites: Role of Fibrin Glue in its Management

Chylous ascites is the accumulation of triglyceride-rich lymph in the abdomen. Its occurrence during the infantile period is quite rare. Congenital chylous ascites (CCA) is one, which occurs in children <3 months of age, due to maldevelopment of the lymphatic system. There is no clearly defined treatment protocol for CCA; however, the use of medium-chain triglycerides (MCT)-based diet or total parenteral nutrition (TPN) with octreotide has been successful. Failure of conservative management, however, leads to surgical exploration to deal with those leaking lymphatics. In our case, we had initially given a trial of managing the child with MCT-based diet followed by a TPN along with octreotide. However, the failure of both leads us to operate the child during which we incorporated the use of fibrin glue over the leaking mesenteric lymphatic vesicles, which ultimately led to the resolution of the chylous ascites.

Fabrication of chondrocytes/chondrocyte-microtissues laden fibrin gel auricular scaffold for microtia reconstruction

Fibrin gel-based scaffolds have promising potential for microtia reconstruction. Autologous chondrocytes and chondrocyte cell sheets are frequently used seed cell sources for cartilage tissue engineering. However, the aesthetic outcome of chondrocyte-based microtia reconstruction is still not satisfactory. In this study, we aimed to fabricate the chondrocytes/chondrocyte-microtissues laden fibrin gel auricular scaffold for microtia reconstruction. We designed a unique auricular mold that could fabricate a fibrin gel scaffold resembling human auricle anatomy. Primary chondrocytes were harvested from rabbit auricular cartilage, and chondrocyte cell sheets were developed. Chondrocyte-microtissues were prepared from the cell sheets. The mixture of chondrocytes/chondrocyte-microtissues was laden in fibrin gel during the auricular scaffold fabrication. The protrusions and recessed structure in the auricular scaffold surface were still clearly distinguishable. After a one-week in vitro culture, the 3 D structure and auricular anatomy of the scaffold were retained. And followed by eight-week subcutaneous implantation, cartilaginous tissue was regenerated in the artificial auricular structure as indicated by the results of H&E, Toluidine blue, Safranin O, and type II collagen (immunohistochemistry) staining. Protrusions and depressions of the auricular scaffold were slightly deformed, but the overall auricular anatomy was maintained after 8-week in vivo implantation. Extracellular matrix components content were similar in artificial auricular cartilage and rabbit native auricular cartilage. In conclusion, the mixture of chondrocytes/chondrocyte-microtissues laden fibrin gel auricular scaffold showed a promising potential for cartilaginous tissue regeneration, suggesting this as an effective approach for autologous chondrocyte-based microtia reconstruction.

Endoscopic management of gastrointestinal leaks and fistulae: What option do we have?

Gastrointestinal leaks and fistulae are serious, potentially life threatening conditions that may occur with a wide variety of clinical presentations. Leaks are mostly related to post-operative anastomotic defects and are responsible for an important share of surgical morbidity and mortality. Chronic leaks and long standing post-operative collections may evolve in a fistula between two epithelialized structures. Endoscopy has earned a pivotal role in the management of gastrointestinal defects both as first line and as rescue treatment. Endotherapy is a minimally invasive, effective approach with lower morbidity and mortality compared to revisional surgery. Clips and luminal stents are the pioneer of gastrointestinal (GI) defect endotherapy, whereas innovative endoscopic closure devices and techniques, such as endoscopic internal drainage, suturing system and vacuum therapy, has broadened the indications of endoscopy for the management of GI wall defect. Although several endoscopic options are currently used, a standardized evidence-based algorithm for management of GI defect is not available. Successful management of gastrointestinal leaks and fistulae requires a tailored and multidisciplinary approach based on clinical presentation, defect features (size, location and onset time), local expertise and the availability of devices. In this review, we analyze different endoscopic approaches, which we selected on the basis of the available literature and our own experience. Then, we evaluate the overall efficacy and procedural-specific strengths and weaknesses of each approach.

Use of hemostatic agents for surgical bleeding in laparoscopic partial nephrectomy: Biomaterials perspective

In recent years, there was an abrupt increase in the incidence of renal tumors, which prompt up the appearance of cutting-edge technology, including minimally invasive and organ-preserving approaches, such as laparoscopic partial nephrectomy (LPN). LPN is an innovative technique used to treat small renal masses that have been gaining popularity in the last few decades due to its promissory results. However, the bleeding control remains the main challenge since the majority of currently available hemostatic agents (HAs) used in other surgical specialities are inefficient in LPN. This hurried the search for effective HAs adapted for LPN surgical peculiarities, which resulted on the emergence of different types of topical HAs. The most promising are the natural origin HAs because of their inherent biodegradability, biocompatibility, and lowest toxicity. These properties turn them top interests' candidates as HAs in LPN. In this review, we present a deep overview on the progress achieved in the design of HAs based on natural origin polymers, highlighting their distinguishable characteristics and providing a clear understanding of their hemostat's role in LPN. This way it may be possible to establish a structure-composition properties relation, so that novel HAs for LPN can be designed to explore current unmet medical needs.

Neuroprotection and immunomodulation by dimethyl fumarate and a heterologous fibrin biopolymer after ventral root avulsion and reimplantation

Background:

Ventral root avulsion (VRA) is an experimental approach in which there is an abrupt separation of the motor roots from the surface of the spinal cord. As a result, most of the axotomized motoneurons degenerate by the second week after injury, and the significant loss of synapses and increased glial reaction triggers a chronic inflammatory state. Pharmacological treatment associated with root reimplantation is thought to overcome the degenerative effects of VRA. Therefore, treatment with dimethyl fumarate (DMF), a drug with neuroprotective and immunomodulatory effects, in combination with a heterologous fibrin sealant/biopolymer (FS), a biological glue, may improve the regenerative response.

Methods:

Adult female Lewis rats were subjected to VRA of L4-L6 roots followed by reimplantation and daily treatment with DMF for four weeks. Survival times were evaluated 1, 4 or 12 weeks after surgery. Neuronal survival assessed by Nissl staining, glial reactivity (anti-GFAP for astrocytes and anti-Iba-1 for microglia) and synapse preservation (anti-VGLUT1 for glutamatergic inputs and anti-GAD65 for GABAergic inputs) evaluated by immunofluorescence, gene expression (pro- and anti-inflammatory molecules) and motor function recovery were measured.

Results:

Treatment with DMF at a dose of 15 mg/kg was found to be neuroprotective and immunomodulatory because it preserved motoneurons and synapses and decreased astrogliosis and microglial reactions, as well as downregulated the expression of pro-inflammatory gene transcripts.

Conclusion:

The pharmacological benefit was further enhanced when associated with root reimplantation with FS, in which animals recovered at least 50% of motor function, showing the efficacy of employing multiple regenerative approaches following spinal cord root injury.

Recent Advances in Tissue Adhesives for Clinical Medicine

Tissue adhesives have attracted more attention to the applications of non-invasive wound closure. The purpose of this review article is to summarize the recent progress of developing tissue adhesives, which may inspire researchers to develop more outstanding tissue adhesives. It begins with a brief introduction to the emerging potential use of tissue adhesives in the clinic. Next, several critical mechanisms for adhesion are discussed, including van der Waals forces, capillary forces, hydrogen bonding, static electric forces, and chemical bonds. This article further details the measurement methods of adhesion and highlights the different types of adhesive, including natural or biological, synthetic and semisynthetic, and biomimetic adhesives. Finally, this review article concludes with remarks on the challenges and future directions for design, fabrication, and application of tissue adhesives in the clinic. This review article has promising potential to provide novel creative design principles for the generation of future tissue adhesives.

Feasibility of autologous fibrin glue in general thoracic surgery

Background

Fibrin glue effectively controls air leakage in lung surgery; however, allogenic fibrin glue cannot eliminate the risks of infection and allergy despite current sterilization methods. Autologous fibrin glue (AFG) could be a good alternative, but is not commonly used worldwide because of its limited availability and lack of evidence. Herein, we report clinical outcomes of AFG in thoracic surgery.

Methods

We retrospectively analyzed patients who underwent lobectomies or segmentectomies between November 2016 and September 2017 in our institution. We used two types of AFGs. One was a partially-autologous fibrin glue (PAFG), the components of which are largely autologous but which contains allogenic thrombin. The other was a completely-autologous fibrin glue (CAFG) which has no allogenic components. PAFG was used in the first half of the study period, after which CAFG was used from March 2017 onward. Patients who did not undergo AFG generation were categorized as the non-AFG group. The perioperative outcomes of the three groups were evaluated.

Results

A total of 207 patients underwent lung surgery, including 118 lobectomies and 89 segmentectomies. Among them, 83 patients received PAFG, 94 received CAFG, and 30 received non-AFG. The mean postoperative drainage period was within a few days in each group (PAFG vs. CAFG vs. non-AFG: 3.23±3.91 vs. 3.16±4.04 vs. 3.17±4.16 days, respectively; P=0.405), and the incidence of postoperative prolonged air leakage was within an acceptable range (PAFG vs. CAFG vs. non-AFG: 13.3% vs. 12.8% vs. 16.7%, respectively; P=0.821).

Conclusions

The use of AFG is clinically feasible for patients who undergo lobectomies or segmentectomies. AFGs could be a viable alternative to conventional allogenic fibrin glues.