Safety evaluation of surgical materials by cytotoxicity testing

The Determination of the Biocompatibility of New Compositional Materials, including Carbamide-Containing Heterocycles of Anti-Adhesion Agents for Abdominal Surgery

Due to traumatic injuries, including those from surgical procedures, adhesions occur in over 50% of cases, necessitating exclusive surgical intervention for treatment. However, preventive measures can be implemented during abdominal organ surgeries. These measures involve creating a barrier around internal organs to forestall adhesion formation in the postoperative phase. Yet, the effectiveness of the artificial barrier relies on considerations of its biocompatibility and the avoidance of adverse effects on the body. This study explores the biocompatibility aspects, encompassing hemocompatibility, cytotoxicity, and antibacterial and antioxidant activities, as well as the adhesion of blood serum proteins and macrophages to the surface of new composite film materials. The materials, derived from the sodium salt of carboxymethylcellulose modified by glycoluril and allantoin, were investigated. The research reveals that film materials with a heterocyclic fragment exhibit biocompatibility comparable to commercially used samples in surgery. Notably, film samples developed with glycoluril outperform the effects of commercial samples in certain aspects.

[Fundamentals and practice of the application of nasal packing in sinonasal surgery]

BACKGROUND AND OBJECTIVES

This paper presents an overview on nasal packing materials which are available in Germany. The current literature is analyzed whether there are robust criteria regarding use nasal packing after sinonasal surgery, whether there are fundamental and proven advantages or disadvantages of products, and what this means in clinical practice.

MATERIALS AND METHODS

Selective literature analysis using the PubMed database (key words "nasal packing", "nasal tamponade", "nasal surgery", "sinonasal surgery", or "sinus surgery"), corresponding text books and resulting secondary literature.

RESULTS AND CONCLUSIONS

Because of systematic methodological shortcomings, the literature does not help in the decision-making about which nasal packing should be used after which kind of sinonasal surgery. In fact, individual approaches for the many different clinical scenarios are recommended. In principle, nasal packing aims in hemostasis, should promote wound healing, and should not result in secondary morbidity. Nasal packing materials should be smooth (non-absorbable materials), inert (absorbable materials), and should not exert excessive pressure. Using non-absorbable packing entails the risk of potentially lethal aspiration and ingestion. For safety reasons inpatient control is recommended as long as this packing is in situ. With other, uncritical packing materials and in patients with special conditions, outpatient control could be justified.

Nanoparticles Stokes radius assessment through permeability coefficient determination within a new stratified epithelium on-chip model

Tissue barrier permeability plays a crucial role in determining the selective transport of substances across epithelial tissues, including drugs, cosmetic substances, and chemicals. The ability of these substances to cross through tissue barriers affects their absorption into the bloodstream and ultimately their effectiveness. Therefore, the determination of their permeability on these type of tissue barriers represents a useful tool for pharmaceutical and cosmetic industries as well as for toxicological studies.In this regard, microfluidic devices and organ-on-chip technologies are becoming more important to generate reliable data. We have designed and performed an alternative new stratified epithelia-on-chip model that allows to correlate the Stokes radius and the diffusion of molecules and/or nanoformulations through the in vitro generated barrier and establish a system suitable for the analysis of diffusion through stratified epithelium. Thus, extrapolating from experimental data we can predict the Stokes radius for unknown fluorescent labelled particles within a molecular size range, such as gold nanoparticles.

A new hemostatic agent composed of Zn2+-enriched Ca2+ alginate activates vascular endothelial cells in vitro and promotes tissue repair in vivo

To control capillary bleeding, surgeons may use absorbable hemostatic agents, such as Surgicel® and TachoSil®. Due to their slow resorption, their persistence in situ can have a negative impact on tissue repair in the resected organ. To avoid complications and obtain a hemostatic agent that promotes tissue repair, a zinc-supplemented calcium alginate compress was developed: HEMO-IONIC®. This compress is non-absorbable and is therefore removed once hemostasis has been achieved. After demonstrating the hemostatic efficacy and stability of the blood clot obtained with HEMO-IONIC, the impact of Surgicel, TachoSil, and HEMO-IONIC on cell activation and tissue repair were compared (i) in vitro on endothelial cells, which are essential to tissue repair, and (ii) in vivo in a mouse skin excision model. In vitro, only HEMO-IONIC maintained the phenotypic and functional properties of endothelial cells and induced their migration. In comparison, Surgicel was found to be highly cytotoxic, and TachoSil inhibited endothelial cell migration. In vivo, only HEMO-IONIC increased angiogenesis, the recruitment of cells essential to tissue repair (macrophages, fibroblasts, and epithelial cells), and accelerated maturation of the extracellular matrix. These results demonstrate that a zinc-supplemented calcium alginate, HEMO-IONIC, applied for 10 min at the end of surgery and then removed has a long-term positive effect on all phases of tissue repair.

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A new Zn2+ enriched Ca2+ alginate hemostatic agent, HEMO-IONIC, has been developed.

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Non-absorbable, it achieves hemostasis with no foreign bodies left in the wound.

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HEMO-IONIC stimulates endothelial cell migration in vitro and angiogenesis in vivo.

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HEMO-IONIC, removed 10 min after application, promotes all stages of tissue repair.

Safety, efficacy, and operability of a newly developed absorbable adhesion barrier (GM142) in patients with primary rectal cancer scheduled for diverting ileostomy during laparoscopic surgery: Randomized controlled trial

Aim

The aim of this study was to compare the outcomes of GM142, a newly developed gelatin film with a concave and convex structure to a commercially available conventional film, hyaluronate-carboxymethylcellulose.

Methods

Patients with primary rectal cancer who were scheduled for diverting ileostomy during laparoscopic surgery were eligible for this study. Patients were randomized before surgery and an antiadhesion film was applied under the umbilical incision. The primary outcome was the incidence of adhesion under the midline incision confirmed by second-look surgery for diverting ileostomy closure. The secondary outcomes were the adhesion severity score, the extent of adhesion score, the presence of intestinal obstruction, and the success of all patching.

Results

A total of 146 patients were enrolled. A total of 123 patients were included in the full analysis set. The primary outcome of "no adhesion" was observed in 66.1% in the GM142 group and 55.7% in the conventional film group. The noninferiority of GM142 to conventional film was confirmed (P = .0005). The secondary outcomes were similar between the groups. For the safety evaluation, there were no safety concerns regarding allergic reactions to gelatin or increased gelatin-specific IgE antibody titers.

Conclusions

The noninferiority of GM142 to conventional film was shown. GM142 showed no major safety issues. The clinical safety profiles of GM142 suggested certain physiological benefits of the gelatin film as an adhesion barrier.

Effect of naturally derived surgical hemostatic materials on the proliferation of A549 human lung adenocarcinoma cells

Hemostatic materials are generally applied in surgical operations for cancer, but their effects on the growth and recurrence of tumors are unclear. Herein, three commonly used naturally derived hemostatic materials, gelatin sponge, Surgicel (oxidized regenerated cellulose), and biopaper (mixture of sodium hyaluronate and carboxymethyl chitosan), were cocultured with A549 human lung adenocarcinoma cells in vitro. Furthermore, the performance of hemostatic materials and the tumorigenicity of the materials with A549 ​cells were observed after subcutaneous implantation into BALB/c mice. The in vitro results showed that biopaper was dissolved quickly, with the highest cell numbers at 2 and 4 days of culture. Gelatin sponges retained their structure and elicited the least cell infiltration during the 2- to 10-day culture. Surgicel partially dissolved and supported cell growth over time. The in vivo results showed that biopaper degraded rapidly and elicited an acute Th1 lymphocyte reaction at 3 days after implantation, which was decreased at 7 days after implantation. The gelatin sponge resisted degradation and evoked a hybrid M1/M2 macrophage reaction at 7–21 days after implantation, and a protumor M2d subset was confirmed. Surgicel resisted early degradation and caused obvious antitumor M2a macrophage reactions. Mice subjected to subcutaneous implantation of A549 ​cells and hemostatic materials in the gelatin sponge group had the largest tumor volumes and the shortest overall survival (OS), while the Surgicel and the biopaper group had the smallest volumes and the longest OS. Therefore, although gelatin sponges exhibited cytotoxicity to A549 ​cells in vitro, they promoted the growth of A549 ​cells in vivo, which was related to chronic M2d macrophage reaction. Surgicel and biopaper inhibited A549 ​cell growth in vivo, which is associated with chronic M2a macrophage reaction or acute Th1 lymphocyte reaction.

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The gelatin sponge, Surgicel and biopaper had different effects on A549 ​cell growth and proliferation.

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Biopaper degraded rapidly in vivo and elicited an antitumor Th1 lymphocyte reaction at acute inflammatory phase.

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The gelatin sponge resisted degradation and evoked a protumor M2d macrophage reactions.

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Surgicel resisted early degradation and caused obvious antitumor M2a macrophage reactions.

The effect of chemical and structural modifiers on the haemostatic process and cytotoxicity of the beta-chitin patch

Beta-chitin patch has previously been proven to be an effective haemostat, but whether modifying the patch affects its efficacy and safety, remains unanswered. In this study, the patch was modified using polyethylene oxide, Pluronic-F127, calcium, increased thickness or polyphosphate, and their effect on the process of haemostasis and cytotoxicity was tested and compared with standard-of-care, Surgicel and FloSeal. Whole blood collected from volunteers was applied to the patches to test their whole blood clotting and thrombin generation capacities, whilst platelet isolates were used to test their platelet aggregation ability. The fluid absorption capacity of the patches was tested using simulated body fluid. Cytotoxicity of the patches was tested using AlamarBlue assays and PC12 cells and the results were compared with the standard-of-care. In this study, beta-chitin patch modifications failed to improve its whole blood clotting, platelet aggregation and thrombin generation capacity. Compared to non-modified patch, modifications with polyethylene oxide or calcium reduced platelet aggregation and thrombin generation capacity, while increasing the thickness or adding polyphosphate decreased platelet aggregation capacity. The cytotoxicity assays demonstrated that the beta-chitin patches were non-toxic to cells. In vivo research is required to evaluate the safety and efficacy of the beta-chitin patches in a clinical setting.

Efficacy and safety of Seprafilm for preventing intestinal obstruction after gastrointestinal neoplasms surgery: a systematic review and meta-analysis

OBJECTIVE

It was controversial that hyaluronate-carboxy-methylcellulose-based membrane (Seprafilm) could prevent intestinal obstruction after gastrointestinal neoplasms operation. This study aimed to evaluate the efficacy and safety of Seprafilm in preventing postoperative intestinal obstruction of gastrointestinal neoplasms patients.

METHODS

A systematic research of multiple databases was performed to identify relevant studies, and the studies satisfying the inclusion criteria were included. Risk ratio (RR), weighted mean difference (WMD), and 95% confidence intervals were calculated using RevMan 5.3.

RESULTS

2937 patients from 10 studies who were enrolled in this meta-analysis were divided into the Seprafilm group (n = 1334) and the control group (n = 1603). The Seprafilm group had lower incidence of intestinal obstruction (RR, 0.52; 95% CI, 0.38-0.70; p < .0001), reoperation rates due to intestinal obstruction (RR, 0.48; 95% CI, 0.28 - 0.80; p = .005), incidence of overall complications (RR, 0.77; 95% CI, 0.61-0.97; p = .03) and higher serum creatinine on postoperative day 5 (WMD, 0.15; 95% CI, 0.05-0.25; p = .003). There were no differences regarding time to intestinal obstruction after operation, aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, white blood cell count results on day 5 and 7, serum creatinine on day 7, hospital stay, and incidence of intra-abdominal infection, wound infection, anastomotic leakage between the 2 groups.

CONCLUSIONS

This meta-analysis provided valuable evidence-based support for the efficacy and safety of Seprafilm in preventing postoperative intestinal obstruction of gastrointestinal neoplasms patients. However, more multicenter randomized controlled trials from different countries are needed.

Viability evaluation of layered cell sheets after ultraviolet light irradiation of 222 nm

Introduction

The objective of this study was to evaluate the cell viability of layered cell sheets, irradiated with 222 nm UV light.

Methods

UV transmittance of 222 nm and 254 nm was evaluated when the cell sheets of NCTC Clone 929 cells were irradiated UV light. Cell viability was evaluated after irradiation of 222 nm using 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. Following irradiation of two layered cell sheets at 500 mJ/cm², the cell damage of lower layers was evaluated by a colony formation and MTT assays.

Results

The UV transmittance of 222 nm was 10 times less than that of 254 nm. A MTT assay revealed that cells of cell sheets irradiated at 222 nm was less damaged than those at 254 nm, when irradiated at 5 mJ/cm². Cell colonies were formed for cells of lower layers irradiated at 222 nm whereas no colony formation was observed for those irradiated at 254 nm. Significantly higher MTT activity was observed for cells of lower layers irradiated at 222 nm than at 254 nm.

Conclusions

It is concluded that 222 nm irradiation is biologically safe for cell viability.

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The cell viability of two-layered cell sheets was evaluated after irradiation of UV light at 222 nm.

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UV light at 222 nm is safer to the lower layer than the conventional UV light at 254 nm.

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The reason can be attributed to the lower transmission of UV light at 222 nm through cell sheets.

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UV light at 222 nm could be one of promising tools to be required for the sterilization in the field of regenerative therapy.

Construction of a composite hydrogel of silk sericin via horseradish peroxidase-catalyzed graft polymerization of poly-PEGDMA

Silk sericin (SS), which is one of the main components of Bombyx mori silk fibers, has attracted increasing attentions as functional biomaterials due to its diverse biological activities as well as excellent biocompatibility. However, the poor formability and weak mechanical properties of SS materials severely limit their practical applications in biomedical field. To address this issue, in this study poly(ethylene glycol)dimethacrylate (PEGDMA) modified sericin were prepared by graft polymerization of poly-PEGDMA (pPEGDMA) onto sericin chains in the presence of horseradish peroxidase and hydrogen peroxide under mild condition. The composite hydrogels obtained from the modified SS not only exhibit much improved formability and excellent mechanical properties, but also high possess porosity and swelling ratios up to 63 and 1,250%, respectively, at the optimized formulation. Moreover, the composite hydrogels also reveal sustained drug release behavior and acceptable cytotoxicity, which endow them with vast application as biomaterials. It is envisioned that the method presented in this study would expand the application of SS in biomedical filed.

Enzymatic deposition of PPy onto cPEG-grafted silk fibroin membrane to achieve conductivity

Laccase-mediated graft polymerization of polypyrrole (PPy) onto the SF-g-cPEG membrane was performed to achieve electrical conductivity.

Effect of oxidized cellulose on human respiratory mucosa and submucosa and its implications for endoscopic skull-base approaches

BACKGROUND

Regenerated oxidized cellulose (ROC) sheets have gained popularity as an adjunct to a vascularized nasoseptal flap for closure of dural defects after endoscopic endonasal skull-base approaches (EESBS). However, evidence supporting its impact on the healing process is uncertain. This study was performed to evaluate the impact of ROC on the nasal mucosa and assess its effects on tissue pH, structure, and cell viability.

METHODS

In 5 patients, a 1-cm² piece of ROC gauze was placed on the surface of the middle turbinate before it was resected as part of a standard EESBS. Mucosa treated with ROC was separated from untreated mucosa and a histologic examination of structural changes in the respiratory epithelium was performed. To assess the effect of ROC on pH, increasing amounts of ROC were added to culture medium. Nasal fibroblasts viability was assessed in the presence of ROC before and after the pH was neutralized.

RESULTS

Compared with unexposed controls, treated mucosa exhibited a higher incidence of cell necrosis and epithelial cell detachment. When added to Dulbecco's modified Eagle medium, ROC caused a dose-dependent decrease in pH of the medium. Only 1 ± 0.8% of cultured fibroblasts exposed to the ROC-induced acidic medium were alive, whereas 98.25 ± 0.5% of the cells were viable when the pH was neutralized (p < 0.001).

CONCLUSION

ROC applied in vivo to nasal mucosa induced epithelial necrosis likely by diminishing the medium pH, because pH neutralization prevents its effect. The ultimate effect of this material on the healing process is yet to be determined.

Oxidized regenerated cellulose cross-linked gelatin microparticles for rapid and biocompatible hemostasis: A versatile cross-linking agent

Effective hemostatic materials are of utmost importance for preventing bleeding in emergencies and critical injuries. Combining biodegradability, good hemostatic properties and biocompatibility, gelatin is one of the most reliable materials clinically used for preventing internal bleeding in surgeries and for stopping external hemorrhage. Cross-linking is a useful method for enhancing the absorption capacity of gelatin and for controlling the degradation process. Existing and commonly used aldehyde-containing cross-linking agents lack reliability with respect to the control of hemostatic effect, solubility and toxicity. In this study; gelatin was cross-linked with sodium oxidized regenerated cellulose (NaORC) to produce hemostatic microparticles. The NaORC was used at different ratios; and the studies on hemostatic efficiency and cytotoxicity under in vitro conditions demonstrated rapid arrest of bleeding alongside biocompatibility. These microparticles employing NaORC as a cross-linking agent for the first time demonstrated a unique structure for stopping bleeding with biocompatibility, and opened the way for different forms of cross-linked structures to be used in other biomaterials applications.

A comparison of in vitro cytotoxicity assays in medical device regulatory studies

Medical device biocompatibility testing is used to evaluate the risk of adverse effects on tissues from exposure to leachates/extracts. A battery of tests is typically recommended in accordance with regulatory standards to determine if the device is biocompatible. In vitro cytotoxicity, a key element of the standards, is a required endpoint for all types of medical devices. Each validated cytotoxicity method has different methodology and acceptance criteria that could influence the selection of a specific test. In addition, some guidances are more specific than others as to the recommended test methods. For example, the International Organization for Standardization (ISO¹) cites preference for quantitative methods (e.g., tetrazolium (MTT/XTT), neutral red (NR), or colony formation assays (CFA)) over qualitative methods (e.g., elution, agar overlay/diffusion, or direct), while a recent ISO standard for contact lens/lens care solutions specifically requires a qualitative direct test. Qualitative methods are described in United States Pharmacopeia (USP) while quantitative CFAs are listed in Japan guidance. The aim of this review is to compare the methodologies such as test article preparation, test conditions, and criteria for six cytotoxicity methods recommended in regulatory standards in order to inform decisions on which method(s) to select during the medical device safety evaluation.

HRP-mediated graft polymerization of acrylic acid onto silk fibroins and in situ biomimetic mineralization

Silk fibroin (SF) can be extensively utilized in biomedical areas owing to its appreciable bioactivity. In this study, biocompatible composites of SF and hydroxyapatite (HAp) were fabricated through in situ biomimetic mineralization process. Graft copolymerization of acrylic acid (AA) onto SF was conducted by using the catalytic system of acetylacetone (ACAC), hydrogen peroxide (H₂O₂) and horseradish peroxidase (HRP), for enhancing the deposition of apatite onto the fibroin chains. Subsequently, biomimetic mineralization of the prepared fibroin-based membrane was performed in Ca/P solutions to synthesize the organized SF/HAp composites. The efficacies of graft copolymerization and biomimetic mineralization were evaluated by means of ATR-FTIR, GPC, EDS-Mapping, XRD and others. The results denoted that AA was successfully graft-copolymerized with fibroin and formed the copolymer of silk fibroin-graft-polyacrylic acid (SF-g-PAA), and the grafting percentage (GP) and grafting efficiency (GE) under the optimal condition reached to 23.2% and 29.4%, respectively. More mineral phases were detected on the surface of SF-g-PAA membrane after mineralization process when compared to that of the untreated fibroin membrane, companying with an improved mechanical property. According to MG-63 cell viability and fluorescent adhesion assays, the mineralized SF-g-PAA composite showed satisfactory biocompatibility and exceptional adhesive effects as well. The synthetized composite of SF-g-PAA/HAp can be potentially applied in the fields of bone tissue engineering.

Postoperative cytological findings from the use of the Integran microfibrillar collagen hemostatic matrix in conization

The Integran microfibrillar collagen hemostatic matrix is one form of microfibrillar collagen hemostat. This form has a sheet-type structure and has explicitly been used in Japan. In gynecology, this sheet-type matrix has helped effect uterine surface hemostasis, especially in myomectomy and cervical conization. However, cytotechnologists and pathologists have overlooked the foreign materials used for conization in postoperative cervical cytology. We report two cases describing the characteristic cervical cytology findings when Integran was used in conization. The first case was a 67-year-old woman who underwent conization because of cervical intraepithelial neoplasia (CIN) 3. Thirty-six days after the surgery, many cylindrical fragments of glossy acellular materials appeared in the cervical cytology. Fortunately, the content did not impede the diagnosis of NILM. The patient then underwent hysterectomy two months after conization. Surgical specimen revealed a high degree of inflammation and granulation without malignancy. Following surgery, the cylindrical fragments disappeared from microscopic findings. The second case was a 45-year-old woman who underwent conization because of CIN3. Thirty-four days after the surgery, many tubular pieces of glossy acellular materials appeared in cervical cytology, as seen in the first case. The cytological diagnosis was NILM. One hundred days after surgery, cervical cytology revealed many clue cells but no cylindrical fragments. These clusters of cylindrical fragments of glossy acellular materials in cervical cytology after conization might induce a delay in diagnosing the persistence and recurrence of cervical cancer. This article is the first report describing cervical cytology findings associated with Integran use.

Comparative Evaluation of Biological Performance, Biosecurity, and Availability of Cellulose-Based Absorbable Hemostats

Hemorrhage remains a leading cause of death after trauma, and developing a hemostat with excellent performance and good biosecurity is an extremely active area of research and commercial product development. Although oxidized regenerated cellulose (ORC) has been developed to address these problems, it is not always efficient and its biosecurity is not perfect. We aimed to refine ORC via a simple and mild neutralization method. The prepared neutralized oxidized regenerated cellulose (NORC) showed a superior gel property due to its chemical structure. The biological performance of both ORC and NORC was systematically evaluated; the results showed that ORC would induce erythema and edema in the irritation test, whereas NORC did not cause any adverse inflammation, indicating NORC had desirable biocompatibility. We further demonstrated that NORC confirmed to the toxicity requirements of International Organization for Standardization (ISO) standards; however, ORC showed an unacceptable cytotoxicity. The rabbit hepatic defect model stated that NORC exhibited better ability of hemostasis, which was attributed to its significant gel performance in physiological environment.

Synthesis of silk fibroin-g-PAA composite using H2O2-HRP and characterization of the in situ biomimetic mineralization behavior

Silk fibroin (SF) as a bioactive protein can offer growth substrates for hydroxyapatite (HAp) deposition. In the current work, graft copolymerization of acrylic acid (AA) onto fibroin chains was carried out using hydrogen peroxide-horseradish peroxidase (H₂O₂-HRP) catalytic system, SF-g-polyacrylic acid (PAA) membranes was prepared subsequently, followed by in situ biomimetic mineralization in the Ca/P solutions, aiming at promoting the deposition of HAp and endowing the fibroin-based biocomposite with enhanced bioactivity. Meanwhile, p-hydroxyphenylacetamide (PHAD) and methyl acrylate (MA), as the model compounds of tyrosine residues in SF and vinyl monomer were used to disclose the mechanism of graft copolymerization. The data from FTIR and SEC chromatograms indicated that vinyl monomer was successfully graft copolymerized with SF during H₂O₂-HRP treatment. According to the results of XRD, SEM patterns and EDS-Mapping, mineral phases on the surfaces of SF-g-PAA membranes were detected after different cycles of biomimetic mineralization, and the mechanical property of SF-g-PAA/HAp membrane was noticeably improved. Cell viability and adhesion assays revealed that the composite of SF-g-PAA/HAp exhibited acceptable biocompatibility and outstanding adhesion property. The present work provides a novel method for preparation of the fibroin-based biomaterial for bone tissue engineering.

In vitro methods of assessing ocular biocompatibility using THP-1-derived macrophages

Macrophages play an important role in the elimination of infections, the removal of debris and in tissue repair after infection and trauma. In vitro models that assess ocular biomaterials for toxicity typically focus on the effects of these materials on epithelial or fibroblast cells. This investigation evaluated known ocular toxins deposited on model materials for their effects on the viability and activation of macrophages. THP-1-derived macrophages were cultured onto silicone films (used as a base biomaterial) deposited with chemical toxins (benzalkonium chloride (BAK), zinc diethyldithiocarbamate (ZDEC) and lipopolysaccharide (LPS)). Utilizing three fluorescent dyes calcein, ethidium homodimer-1 (EthD-1) and annexin V, the viability of macrophages attached to the biomaterial was determined using confocal microscopy. Propidium iodide (PI) staining and alamarBlue® (resazurin) reduction were used to assess cell death and metabolic activity. CD14, CD16, CD33, CD45, and CD54 expression of adherent macrophages, were also evaluated to detect LPS activation of macrophages using flow cytometry. The sensitivity of this test battery was demonstrated as significant toxicity from treated surfaces with ZDEC (0.001-0.01%), and BAK (0.001%-0.1%) was detected. Also, macrophage activation could be detected by measuring CD54 expression after exposure to adsorbed LPS. These in vitro methods will be helpful in determining the toxicity potential of new ocular biomaterials.

Microscopic findings of sheet-type collagen applied to air leaks after pulmonary resection

PURPOSE

It has been reported that Integran(®), a sheet-type absorbable topical collagen hemostat, is feasible for preventing pulmonary fistula after lung surgery. The most favorable aspect of Integran(®) is that it contains no blood products. However, the microscopic findings of post-surgery application of Integran(®) to the lung are not known. We identified 2 such cases of Integran(®) application, which were carried out a few years earlier, and described the microscopic findings.

METHOD

In case 1, a 53-year-old man underwent video-assisted left upper lobectomy for primary lung cancer. Integran(®) was applied to the left lower lobe. Completion left pneumonectomy was performed after 2 years and 1 month due to recurrence. In case 2, a 77-year-old woman underwent video-assisted right middle lobectomy for primary lung cancer. Integran(®) was applied to the right upper lobe. Completion right upper lobectomy was performed after 1 year and 8 months due to recurrence.

RESULTS

The repaired visceral pleura of the 2 patients were covered with proliferated collagen fibers. However, there was little infiltration of inflammatory cells and fibroblasts.

CONCLUSION

The microscopic findings revealed that the ability of Integran(®) to generate inflammation or adhesion is weak, but it has the ability to repair damaged visceral pleura.

Mechanical properties of blood-mixed polymethylmetacrylate in percutaneous vertebroplasty

Study Design

Mechanical study of polymethylmetacrylate (PMMA) mixed with blood as a filler.

Purpose

An attempt was made to modify the properties of PMMA to make it more suitable for percutaneous vertebroplasty (PVP).

Overview of Literature

The expected mechanical changes by adding a filler into PMMA included decreasing the Young's modulus, polymerization temperature and setting time. These changes in PMMA were considered to be more suitable and adaptable conditions in PVP for an osteoporotic vertebral compression fracture.

Methods

Porous PMMA were produced by mixing 2 ml (B2), 4 ml (B4) and 6 ml (B6) of blood as a filler with 20 g of regular PMMA. The mechanical properties were examined and compared with regular PMMA(R) in view of the Young's modulus, polymerization temperature, setting time and optimal passing-time within an injectable viscosity (20-50 N-needed) through a 2.8 mm-diameter cement-filler tube. The porosity was examined using microcomputed tomography.

Results

The Young's modulus decreased from 919.5 MPa (R) to 701.0 MPa (B2), 693.5 Mpa (B4), and 545.6 MPa (B6). The polymerization temperature decreased from 74.2℃ (R) to 59.8℃ (B2), 54.2℃ (B4) and 47.5℃ (B6). The setting time decreased from 1,065 seconds (R) to 624 seconds (B2), 678 seconds (B4), and 606 seconds (B6), and the optimal passing-time decreased from 75.6 seconds (R) to 46.6 seconds (B2), 65.0 seconds (B4), and 79.0 seconds (B6). The porosity increased from 4.2% (R) to 27.6% (B2), 27.5% (B4) and 29.5% (B6). A homogenous microstructure with very fine pores was observed in all blood-mixed PMMAs.

Conclusions

Blood is an excellent filler for PMMA. Group B6 showed more suitable mechanical properties, including a lower elastic modulus due to the higher porosity, less heating and retarded optimal passing-time by the serum barrier, which reduced the level of friction between PMMA and a cement-filler tube.