A novel approach to the problem of intestinal fistulization arising in patients managed with open peritoneal cavities

Open management of the peritoneal cavity is an efficacious technique for controlling fulminant intraabdominal sepsis. A significant proportion of these patients develop intestinal fistulae for which there are few good treatment options. We propose a novel technique for preventing and potentially treating intestinal fistulas that involves patching intestinal deserosalizations and fistulas with acellular dermal matrix (Alloderm) and fibrin glue. We report our experience with this technique in 2 patients who developed small bowel deserosalizations, neither of whom went on to develop fistulas. We additionally describe 1 patient who developed an intestinal fistula for whom we were able to affect closure with this technique. We propose that our method is a useful temporizing measure to prevent fistulae formation. Furthermore, we believe this technique may be a useful option for treating intestinal fistulae arising in patients managed with open abdominal wounds.

Comparative study of the efficacy of the common topical hemostatic agents with fibrin sealant in a rabbit aortic anastomosis model

OBJECTIVE

The purpose of this study was to compare the hemostatic efficacy of the common surgical hemostatic agents with fibrin sealant (FS) and to assess their functional strength to secure hemostasis in lieu of placing additional sutures.

METHODS

End-to-end anastomosis of transected abdominal aorta was performed in moderately anticoagulated rabbits using 4 or 6 interrupted sutures. The suture line was covered either with gauze alone ("untreated") or with gauze plus Gelfoam, Avitene, Surgicel, FloSeal, or FS, following which blood flow was restored. Blood loss was absorbed by gauze and measured. The surviving rabbits were recovered and the repaired vessel was examined histologically 4 weeks after operation. The investigators were blinded to the treatment groups. Aortic anastomoses using 8 or 12 sutures (untreated) were also performed.

RESULTS

Untreated 4-suture anastomosis of aorta resulted in a profuse hemorrhage with an average 108.0 +/- 19.2 (mean +/- SD) ml blood loss and 100% mortality (n = 4). FS application sealed the anastomoses, prevented blood loss (P < 0.01 vs untreated) and exsanguination of the rabbits (n = 4). Other hemostatic agents reduced the bleeding to varying degrees compared to the untreated animals (Gelfoam 66.4 +/- 17.6, Avitene 80.6 +/- 34, Surgicel 66.7 +/- 16.7, FloSeal 44.2 +/- 8.5 ml blood loss, n = 4/group), but the changes were not statistically significant. One to three rabbits in each group survived the operation. Six-suture aortic anastomoses, untreated, resulted in 67.7 +/- 21.8 ml blood loss and 100% survival (n = 6). Application of FS produced immediate and sustained hemostasis in all the animals (P < 0.01 vs untreated). Other hemostatic agents also reduced the bleeding (Gelfoam 42.5 +/- 10, Avitene 50.9 +/- 12.4, Surgicel 32.1 +/- 14, FloSeal 33.9 +/- 5.4 ml blood loss, n = 6/group), but the changes were not statistically significant. The 8- and 12-suture aorta repairs resulted in a moderate blood loss (43.9 +/- 19 and 21.3 +/- 14.9 ml, respectively), followed by a stable hemostasis that precluded the need to use any hemostatic agent. The aortic cross-clamping time of the 12-suture and time to hemostasis for both the 8- and the 12-suture techniques were significantly longer than those of the 4-suture plus FS application (P < 0.01, P < 0.01 and P < 0.05, respectively).

CONCLUSION

In a moderate coagulopathy, FS was proven to be the most efficacious hemostatic agent, producing immediate and sustained hemostasis at the arterial anastomotic site. This high efficacy is in part attributed to the strong tissue adhesive property of this agent. FS application may potentially ease the anastomosis and shorten the duration of timely critical vascular procedures.

A modified method to culture human osteoblasts from bone tissue specimens using fibrin glue

INTRODUCTION

To establish primary osteoblast cultures is a challenge. The methods for isolation mostly comprise digestion with extracellular matrix degrading enzymes after mincing the bone samples. These methods are labour intensive and lead to an inefficient recovery of cells. Therefore, the aim of this study was to develop a more reliable method for culturing human osteoblasts.

MATERIALS AND METHODS

Bone tissue specimens were obtained from 20 patients undergoing reconstructive operations. Bone specimens were dissected and put into petri dishes with the bottom covered with fibrin glue. To identify the nature of the outgrowing cells, cytological staining was performed, i.e. Von Kossa, Azan, Dahl's, alkaline phosphatase, and collagen type I.

RESULTS

Mean time interval of cellular outgrowth was 12 days after preparing the bone tissue specimens. Confluence of the cell cultures was reached after four to five weeks on average. All cells were positively stained using Von Kossa, alkaline Phosphatase and collagen type I. The matrix consisted of lime, calcium and collagens.

CONCLUSION

A simplified method to culture osteoblasts from all kinds of bone tissue specimens is presented. The fibrin glue allows firm adhesion of the specimens to the petri dish. This allows the cells to grow out without disturbance. Normally, due to movements during medium exchange the adhesive bonds are disrupted. The fibrin glue retains the adhesive bonds. This method allows studying human osteoblasts in different clinical settings.

Fibrin glue as an osteoinductive protein in a mouse model

Fibrin sealant or fibrin glue (FG) has been found to be effective as a wound-healing substance in surgery. However, its role in bone fracture healing and osseous tissue response is not fully understood. This ambiguity questions the potential of FG as an inductive protein. The present study was undertaken to evaluate the osteoinductive property of FG when coated with calcium phosphate and glass ceramics and implanted in the extraskeletal site of male Swiss albino mice. Implant materials used for this study were hydroxyapatite (HA) porous granules (300-350 microm), bioactive glass system (BGS)-AW type and calcium phosphate calcium silicate system (HABGS) non-porous granules (300-350 microm). Uncoated granules (control) and coated granules with 2.5 mg FG and 5 mg FG were implanted in the quadriceps muscle of mice and sacrificed after 28 days. Histologically, HA, BGS and HABGS implanted animal groups showed good healing response. However, neo-osteogenesis was observed only in the BGS and HABGS granules impregnated with FG. Furthermore, bone formation was observed to be more conspicuous in 5 mg FG coated BGS and HABGS granules when compared with 2.5 mg FG coated BGS and HABGS granules. Fluorochrome labeling proved that mineralization had already started by day 15 with FG preadsorbed BGS and HABGS granules. On the contrary, the uncoated granules did not show any de novo bone formation. This experimental study provides an evidence of the positive role of FG as a potential osteoinductive biologic tissue adhesive.

Histological effects of fibrin glue on nervous tissue: a safety study in rats

BACKGROUND

Little is known of the histologic effects of fibrin glue on normal nervous tissue. To verify the safety of intracranial application of fibrin glue, we investigated the histologic effects of fibrin glue on brain tissue and intracranial nerves of rats.

METHODS

In Group I (n = 12), bifrontal craniotomy with opening of the dura and arachnoid was performed, and on one side one droplet of fibrin glue was applied into the subarachnoid space. In Group II (n = 12), a unilateral temporal craniotomy was performed, the cavernous sinus was opened, and one drop of fibrin glue was applied to the trigeminal nerve. The controls for Group II (n = 8) were operated in the same way but without application of the fibrin glue. Rats were sacrificed at 1, 3, 7, and 28 days after surgery. The brains and nerves were processed for histologic examination and were semi-quantitatively scored for neuronal damage, gliosis, edema, fibroplasia, inflammatory reaction, axonal damage, and myelin damage.

RESULTS

No differences were found in the occurrence of neuronal damage, gliosis, edema, fibroplasia, axonal damage, or myelin damage between rats with and without fibrin glue application. In Group I the inflammatory reaction seen at Day 7 was more severe on the fibrin glue side when compared to the control side. At Day 28, however, this difference had resolved.

CONCLUSIONS

In this morphological safety study, intracranial application of fibrin glue in a rat model does not induce extra brain damage, intracranial nerve damage, or scar tissue formation.

Intraspinal implants of fibrin glue containing glial cell line-derived neurotrophic factor promote dorsal root regeneration into spinal cord

OBJECTIVE

The purpose of this study was to determine whether glial cell line-derived neurotrophic factor (GDNF) delivered intraspinally via a fibrin glue (FG) enhanced regeneration of cut dorsal root (DR).

METHODS

FG containing GDNF was inserted into aspiration cavities in the lumbar enlargement of adult rats. The transected L5 DR stump was placed at the bottom of the cavity and sandwiched between the FG and the spinal cord. Regenerated DR axons were labeled with horseradish peroxidase (HRP) or with immunohistochemical methods for calcitonin gene-related peptide (CGRP).

RESULTS

Primary afferent axons labeled with HRP regenerated into the spinal cord, received GDNF, and made frequent arborization there. Some of these were myelinated axons that established synapses on intraspinal neuronal profiles. CGRP-immunoreactive DR axons extended into the motor neurons and formed prominent varicosities around their cell bodies. Only a few axons regenerated into the spinal cords given FG without GDNF.

CONCLUSIONS

Our results indicate that GDNF enhances regeneration of DR into the adult rat spinal cord and that GDNF may be effectively supplied to the intraspinal injury site via FG. Because the regenerated axons establish synapses on intraspinal neurons, this therapeutic strategy has the potential to help to rebuild spinal reflex circuits interrupted by spinal cord injury.

Perivenous application of fibrin glue reduces early injury to the human saphenous vein graft wall in an ex vivo model

OBJECTIVES

From animal and clinical studies it is known that prevention of 'over-distention' of vein grafts by using extravascular support ameliorates the arterialization process in vein grafts with subsequent more favorable patency. The most ideal support is a biodegradable, porous, elastic graft (Biomaterials, 15 (1994) 83). However, a specific graft meeting these criteria is not available yet. Fibrin glue on the other hand, although used for other purposes in cardiac surgery, theoretically meets the criteria for ideal extravascular support. In this ex vivo study, we evaluated the possible beneficial effect of perivenous application of fibrin glue.

METHODS

Segments of human vein graft obtained during CABG procedures in 14 consecutive patients were placed in a side loop of the extracorporeal perfusion circuit. In this way the study vein grafts did meet identical circumstances as the vein grafts implanted. Perfusion in the loop was started with a flow just enough to counteract the collapse of the vein, usually about 8 mm Hg, and alternately around the segments fibrin glue was applied or no perivenous support was administered as control. After 1 min of soldification, perfusion was started with a pressure of about 60 mm Hg (non-pulsatile flow). Perfusion was maintained for 60 min, after which the grafts were collected for light microscopic and electron microscopic assessment.

RESULTS

Light microscopy and electron microscopy showed remarkable attenuation of endothelial cell loss and less injury of smooth muscle cells of the circular muscle layer of the media in the fibrin glue supported vein grafts compared to the non-supported group.

CONCLUSION

Fibrin glue is able to accomplish adequate external vein graft support, preventing overdistention, in an ex vivo model. This provides a basis for clinical application. Further investigation is necessary to evaluate long-term effects.

The wound-healing effect of fibrin glue for tracheal anastomosis in experimental pulmonary surgery

The leakage of tracheal anastomoses is one of the major complications that occurs after tracheal reconstruction. Improved reinforcing methods for anastomoses would thus be clinically useful. To find a better technique, we examined the postoperative would-healing effect of fibrin glue on tracheal anastomosis in the rat. Experimental rats were divided into two groups. In the control group (n = 21), the trachea was anastomosed by interrupted absorbable sutures. In the fibrin glue group (n = 21), the trachea was anastomosed in the same manner as the control group, with the addition of fibrin glue around the area of anastomosis. In the two groups, we studied the amount of hydroxyproline and histological findings on the seventh, 14th, and 21st postoperative day. The amount of hydroxyproline and collagen fibers in the fibrin glue group was more than in the control group on the seventh postoperative day. These results suggest that fibrin glue has a promotive effect in the healing of tracheal anastomosis.

Expression of Schwann cell-specific proteins and low-molecular-weight neurofilament protein during regeneration of sciatic nerve treated with neurotrophin-4

Neurotrophin-4 acts as a potent survival factor for subpopulations of motoneurons. To investigate its effect on Schwann cell sheath and axonal proteins during peripheral nerve regeneration, sciatic nerves in adult rats were transected and repaired, and fibrin glue containing neurotrophin-4 injected around the repair site. At 5, 15, 30 and 60 days after repair, 5-mm nerve segments distal to the repair were collected, and western blotting was used to measure myelin-associated glycoprotein, myelin basic protein and low-molecular-weight neurofilament protein. In control groups these dramatically declined at 5 and 15 days then increased from 30 and 60 days. However, in the neurotrophin-4 group there was a significant increase (to several times basal values) in myelin-associated glycoprotein and myelin basic protein at 5-15 days. The relatively small increases (<7%) in Schwann cell numbers suggest that this is mainly due to increased synthesis per cell. The neurotrophin-4 group also showed a small but significant increase at 15 days in low-molecular-weight neurofilament protein, which however remained much lower than basal. We conclude that neurotrophin-4 regulates the expression of myelin-associated glycoprotein, myelin basic protein, and to a lesser extent low-molecular-weight neurofilament protein, during peripheral nerve regeneration.

A novel use of alginate hydrogel as Schwann cell matrix

The use of bioresorbable conduits supplemented with Schwann cells (SCs) is a promising tissue engineering technique to replace nerve grafting. Alginate hydrogel (AH), as a SC tissue engineering matrix, has many advantages over previously used matrices but has not been evaluated for this purpose. In this study, the viability and proliferation of SCs together with SC function in AH was evaluated in vitro. AlamarBlue cell assay was used to monitor the viability of SCs in AH and compared to SC viability in collagen gel, fibrin glue, hyaluronic acid, Matrigel, and standard culture plate over 5 days in culture. The results showed that the viability and growth of SCs in different matrices over the culture period did not significantly differ to culture plate culture. SC function when suspended in AH was monitored using chick embryo dorsal root ganglia (CDRG) growth assay. Growth of CDRG in AH with or without SCs was compared to CDRG growth without AH matrix. After 3 days in culture, the mean length of neurite sprouting was measured. The results showed that there was neurite growth in AH but was reduced to 43% of control. The neurite growth in AH was, however, enhanced by 170% when SCs were suspended in the gel. In conclusion, AH supported SC viability and function in vitro and may be useful in peripheral nerve tissue engineering in reconstructive procedures.

Development of an animal model for assessment of the hemostatic efficacy of fibrin sealant in vascular surgery

PURPOSE

Sustained hemostatic function of fibrin sealant (FS) is crucial when it is used in cardiovascular surgery. The purpose of this study was to develop a model that can determine the long-term hemostatic efficacy of tissue sealants in a vascular surgery.

METHODS

To determine the ability of the model to detect differences in FS performance, various concentrations of FS were prepared and tested. Tensile strength of FS clots was determined in vitro using a tensiometer. Laparotomy was performed on 49 anesthetized rabbits, and a segment of the aorta was occluded, transected, and then sutured in an end-to-end fashion with four or eight interrupted 9-O sutures. The four-suture repair was covered with FS or placebo, and blood flow restored. Spilled blood was absorbed with gauze and weighed to estimate blood loss. Four weeks after surgery the animals were euthanized and the vessels recovered for histology.

RESULTS

Average tensile strength of FS clots at 120, 90, and 60 mg/ml topical fibrinogen complex (TFC) concentration was 0.42 +/- 0.07 N, with no significant difference among them. The lowest TFC concentration, 30 mg/ml, produced weaker clots than either 120 or 90 mg/ml (P < 0.05). All rabbits with four-suture anastomoses that were treated with placebo bled to death after the vessel was unclamped (n = 6). Treatment of suture line with standard FS concentration (120 mg/ml TFC, n = 8) sealed the anastomosis and prevented blood loss. Hemostasis was sustained for 4 weeks, allowing vascular healing. All rabbits with the eight-suture anastomosis survived the operation but lost 42 +/- 9.2 ml blood (n = 5). Hemostatic efficacy of FS was unchanged when TFC was diluted to 90 mg/ml (n = 6) but further dilution to 60 mg/ml with water (n = 8) produced significantly less effective clots, with an average blood loss of 5.5 +/- 7.6 ml (P < 0.05) and two fatal clot failures postoperatively. When FS was diluted to 60 mg/ml TFC with a buffer, it maintained its hemostatic strength (n = 6). Further TFC dilution to 30 mg/ml led to consistent bleeding with an average blood loss of 35.3 +/- 10.3 ml (P < 0.001, n = 6).

CONCLUSIONS

The four-suture anastomosis of rabbit aorta offers a consistent and reliable method for evaluating the short- and long-term hemostatic efficacy of FS products. This model is not only able to determine the functional differences in various concentrations of FS, but it is also sensitive to detect the subtle changes in FS preparation (e.g., medium composition) that is not detected by in vitro testing.

Inhibition of intra-abdominal adhesions: a comparison of hemaseel APR and cryoprecipitate fibrin glue

Our previous studies demonstrated fibrin glue (FG) prepared from cryoprecipitate (cryo) inhibits intra-abdominal adhesions in rats. A new FG, Hemaseel APR, is Food and Drug Administration (FDA) approved for hemostasis during cardiac surgery and splenic trauma. This study was undertaken to determine if Hemaseel FG prevents intra-abdominal adhesions, and to compare it to cryo FG. Forty-five rats underwent laparotomy. Bilateral peritoneal-muscular defects were created. Polypropylene mesh was sewn into each defect with a running silk suture. The bowel was abraded with gauze. The rats were then randomized to mesh covered with Hemaseel FG, cryo FG, or control. On postoperative day 7, the severity of adhesions were graded by percentage of mesh covered by adhesion (0-100%) and degree of adhesion (0-3). The mean percentage of mesh covered by adhesion was 9% for Hemaseel FG, 43% for cryo FG (p = .005), and 65% for the controls (p < .0001). The mean density adhesion score was 0.5 for Hemaseel FG, 1.2 for cryo FG (p = .04), and 2.1 for the controls (p < .0001). In the Hemaseel FG group, 77% of patches had no adhesions, compared with 37% in the cryo FG group (p = .004) and 13% in the controls (p < .0001). Thus, Hemaseel FG significantly decreases intra-abdominal adhesions, and is more effective than cryo FG.

Safety and efficacy of currently available fibrin tissue adhesives

PURPOSE

The purpose of this study is to review preparation methods, bonding power, preparation time, and costs associated with currently available autologous and homologous fibrin tissue adhesive preparations.

METHODS

Two autologous fibrin tissue adhesive preparations (AFTA-A and AFTA-E), a single-donor homologous preparation, and 2 multiple-donor pooled homologous fibrin tissue adhesives, Vi-Guard and Tisseel, were evaluated and compared in relation to bonding power, preparation time, cost, bicompatibility, and biodegradability.

RESULTS

Vi-Guard and Tisseel showed significantly greater bonding strengths than their single-donor counterparts. AFTA-C offers the quickest preparation time. All preparations were found to be similar in biocompatibility and biodegradability in soft tissue tests. Histology showed no infection or tissue reaction from adhesive exposure in any of the preparations.

CONCLUSION

The optimal choice of a fibrin tissue adhesive is determined by the particular clinical indication. Currently available fibrin tissue adhesives vary appreciably in their bonding strength, cost, level of exposure risk, and preparation methods and times. Autologous preparations, which offer optimal safety, lack the strength and availability characteristics found with the multiple-donor preparations.

Fibrin sealant: a novel method of fixation for an implantable ultrasonic microDoppler probe

While free tissue transfer affords the reconstructive microvascular surgeon the ability to provide coverage for complex wounds, the postoperative monitoring of these flaps continues to evolve. The most recent advance has been the development of an implantable microDoppler probe to provide an early warning signal for vascular obstruction. The current system relies on the use of a silicone cuff to secure a 1-mm probe to the outflow vein. The release force to remove the probe from the cuff is reported to be 1/10 of a pound (45 g). A disadvantage of this system is the need for a circumferential, relatively inelastic device around the vein. Should the cuff be too tightly secured to the vein, the potential for outflow obstruction exists. Moreover, if the probe is not well-approximated to the vein, no signal is produced. Finally, the fact that a foreign body remains in the wound after completion of the monitoring period remains a concern. The authors have investigated a new method to adhere the probe, using a commercially available fibrin sealant. The use of this biocompatible substance has the potential to obviate the need for the current method of fixation, and the associated concerns.

Aerosolization of Epidermal Cells with Fibrin Glue for the Epithelialization of Porcine Wounds with Unfavorable Topography

Aerosolized epidermal cell suspension was previously found to be effective for the epithelialization of full-thickness wounds. This suspension is less expensive than and requires a shorter preparation time than the currently used cultured epithelial autografts. Still, convex and irregular wounds present unfavorable conditions for homogenous dispersion of the aerosolized cell suspension. The authors hypothesized that the addition of fibrin glue to the aerosol of cells would reduce cell movement and ensure homogenous dispersion of the cells, thereby promoting wound epithelialization. The objectives of the study were to evaluate the healing of wounds with unfavorable topography after autotransplantation of an epidermal cell aerosol with and without fibrin glue. Six Yorkshire piglets were studied. An epidermal suspension was made from full-thickness groin skin. Dispase was used to separate the epidermis from the dermis, and trypsin was used to separate the epidermal cells from one another. Twenty-four hours later, full-thickness wounds with unfavorable topography were created adjacent to the vertebral column of six pigs. Twelve wounds were treated with an aerosol of epidermal cell suspension mixed with fibrin glue (study group), and 12 wounds were treated with the same suspension without the fibrin glue (control group). The percentages of total wound contraction and the epithelialized and nonepithelialized areas were evaluated 1, 2, 3, and 4 weeks after aerosolization. The histologic characteristics of the newly formed skin were examined by light microscopy using slides stained with hematoxylin and eosin. Study wounds were characterized by central epithelialization, whereas control wounds were characterized by peripheral epithelialization. Study wounds contracted at a slower rate than control wounds, but wound size was the same in both groups after 4 weeks. The addition of fibrin glue facilitated epithelialization: Study wounds showed 75.5 +/- 22.4 percent (mean +/- SD) and 94.2 +/- 8.8 percent epithelialization after 3 and 4 weeks, respectively, compared with 46.3 +/- 9.5 percent and 47.9 +/- 13.1 percent epithelialization of the control wounds at the same times. These differences between the study and control groups were statistically significant (p < 0.001, paired t test). The addition of fibrin glue to an aerosol of epidermal cells significantly enhances the epithelialization of wounds with unfavorable topography in pigs.

Evaluation of a fibrin sealant free of bovine-derived components in an experimental vas anastomosis study

OBJECTIVES

The risk of transmission of bovine spongiform encephalopathy cannot be excluded from the use of bovine-derived products. The present study was undertaken to evaluate the performance of a new fibrin glue free of bovine-derived components in vas anastomosis and to compare this product to conventional vas anastomosis with fibrin glue.

METHODS

Bilateral delayed vas anastomosis was performed in 40 Sprague-Dawley rats. All animals underwent a fibrin glue-assisted vas anastomosis with three transmural sutures tied prior to fibrin glue application. The composition and preparation of fibrin glue was similar for all vas anastomoses except the fibrinolysis inhibitor component which was aprotinin (3,000 KUI/ml) in group 1 and tranexamic acid (10 mg/ml) in group 2. The animals (20 rats in both groups) were sacrificed 7 weeks postoperatively and evaluated for gross patency, presence of sperm granuloma and tensile strength measurements at the anastomosis site.

RESULTS

No difference was found between the 2 groups for all parameters evaluated whether a bovine-derived or a synthetic fibrinolysis inhibitor component was used.

CONCLUSION

This study showed that tranexamic acid, a fibrinolysis inhibitor, can be substituted for conventional fibrin glue thereby avoiding the risks of bovine products.

Neurotrophin-4 delivered by fibrin glue promotes peripheral nerve regeneration

Neurotrophin-4 (NT-4) is a recently identified neurotrophic factor with potential trophic effects on subpopulations of neurons. Little is known about its role in peripheral nerve regeneration following nerve injury. To investigate this, 48 Sprague-Dawley rats underwent left sciatic nerve transection and immediate repair. Fibrin glue mixed with either NT-4 or vehicle (control) was injected around the nerve repair site. Nerve regeneration was assessed both functionally and histomorphometrically. The results showed that the NT-4-treated group had a significant increase compared with the control in the regeneration distance at 5 days. The sciatic function index was significantly greater in the NT-4 group from 40 to 60 days after nerve repair. Morphometric analysis revealed that nerves treated with NT-4 had significant improvement in the number of regenerated axons, axonal diameter, and myelin thickness. These results suggest that NT-4 is a potent factor improving rat sciatic nerve regeneration.

Long-term regeneration of human epidermis on third degree burns transplanted with autologous cultured epithelium grown on a fibrin matrix

BACKGROUND

Extensive third degree burn wounds can be permanently covered by the transplantation of autologous cultured keratinocytes. Many modifications to Green and colleagues' original technique have been suggested, including the use of a fibrin matrix. However, the properties of the cultured cells must be assessed using suitable criteria before a modified method of culture for therapeutic purposes is transferred to clinical use, because changes in culture conditions may reduce keratinocyte lifespan and result in the loss of the transplanted epithelium.

METHODS

To evaluate the performances of human keratinocytes grown on a fibrin matrix, we assay for their colony-forming ability, their growth potential and their ability to generate an epidermis when grafted onto athymic mice. The results of these experiments allowed us to compare side by side the performance for third degree burn treatment of autologous cultured epithelium grafts grown according to Rheinwald and Green on fibrin matrices with that of grafts grown directly on plastic surfaces.

RESULTS

We found that human keratinocytes cultured on a fibrin matrix had the same growth capacity and transplantability as those cultured on plastic surfaces and that the presence of a fibrin matrix greatly facilitated the preparation, handling, and surgical transplantation of the grafts, which did not need to be detached enzymatically. The rate of take of grafts grown on fibrin matrices was high, and was similar to that of conventionally cultured grafts. The grafted autologous cells are capable of generating a normal epidermis for many years and favor the regeneration of a superficial dermis.

CONCLUSION

We have demonstrated that: 1) fibrin matrices have considerable advantages over plastic for the culture of skin cells for grafting and that it is now possible to generate and transplant enough cultured epithelium from a small skin biopsy to restore completely the epidermis of an adult human in 16 days; and 2) the generated epidermis self-renews itself for years. The use of fibrin matrices thus significantly improves the transplantation of cultured epithelium grafts for extensive burns as recently demonstrated in a follow-up work.

Purification of salmon clotting factors and their use as tissue sealants

Fibrin sealant prepared from the blood of farmed Atlantic salmon (Salmo salar) represents a potential source of well-controlled natural material with utility in a variety of clinical settings. A potential advantage of this material is a lower probability of viral or bacterial infection that has limited general approval of fibrin glues made from human or bovine proteins. This report describes the purification of fibrinogen from salmon blood, the use of fibrin glues derived from this material to promote wound healing in rats, and the antigenic response to this material. While the low ambient temperature of these cold water fish significantly lessens the probability of infectious transmission to humans, fibrinogen and factor XIII derived from S. salar are activated by human thrombin at 25 degrees C and 37 degrees C to form clots equivalent to those formed by human fibrin. We compare the reactivity of salmon and human fibrinogen with human and bovine thrombin and the structure and viscoelastic properties of the resulting fibrin gels over a range of pH and salt concentrations. The efficacy of salmon fibrin glues in a wound healing assay and the low antigenic response to salmon fibrinogen suggest that this material may substitute for proteins derived from mammalian sources with lower probability of infections.

Convulsive seizures following subdural application of fibrin sealant containing tranexamic acid in a rat model

OBJECTIVES

Tranexamic acid (t-AMCA) has been shown to cause severe convulsions in humans and cats when applied topically to the central nervous system. We wanted to determine whether pure t-AMCA or fibrin sealant (FS) containing t-AMCA would induce similar effects when applied to the spinal cord in a rat model.

METHODS

Following low-thoracic laminectomy, the dura was incised to expose the dorsal surface of the lumbar enlargement. Rats were allocated to one of the following treatments: 1) t-AMCA (10 mg/ml), 2) vehicle (phosphate buffered saline), 3) FS containing t-AMCA, 4) FS containing aprotinin. The response of the rats was evaluated based on neurological and behavioral observations. Additionally, motor function was scored in the rats that had received FS.

RESULTS

Application of either 10 mg/ml t-AMCA or FS containing t-AMCA caused severe hind limb spasms that developed into spontaneous generalized convulsions. Two of the three rats that had received FS containing t-AMCA died of respiratory failure. In contrast, application of vehicle or FS containing aprotinin did not cause any abnormal conditions of the animals.

CONCLUSION

Tranexamic acid may cause severe complications when used in the central nervous system. Thus, fibrin sealants containing t-AMCA should not be used in neurosurgery.

[The effect of fibrin sealant on dental pulp for pulp capping in experimental dogs]

OBJECTIVE

To investigate the pulp tissue reaction and reparative dentine formation of dog pulp capped with Fibrin Sealant (FS).

METHODS

The fibrin was from a tisseel Kit (Immuno AG, Vienna, Austria) consisting of solution A (freeze-dried human fibrinogen, factor XIII, Aprotinine) and solution B (thrombin powder, calcium chloride) with 0.02 ml from each for each tooth. The Ca(OH)2 paste (Calar, China) was served as the control. Forty nine cuspid, premolar and molar teeth in 4 adult dogs weighed 11-13 kg were used. Surgical anesthesia was obtained by muscle injection of 3% sodium pentobarbital (1 ml/kg). The pulp were exposed by using sterile high-speed rotary cutting instruments with water-cooling. The pulps were treated with 0.02 ml fibrin or Ca(OH)2 paste respectively. The cavity was filled with zine phosphate cement. The animals were killed at intervals of 1, 4, 6, 9 weeks after surgery and perfused with phosphate-buffered saline followed by 10% formalin in phosphate-buffered saline. The jaws were resected and the samples prepared by removing each experimental tooth in block, further fixing them by immersion in 10% formalin in phosphate-buffered saline. The specimen were processed for histologic examination. Serial sections (5 nm thick) were made, stained with hematoxylin and eosin, examined using a light microscope.

RESULTS

7 days after operation, the samples treated with the FS showed no hemorrhage and degeneration of pulp tissue and a small amount inflammatory cells near the wounds. The samples treated with Ca(OH)2 showed hemorrhage and degeneration (2/6) and a large amount inflammatory cells near the wounds. 28 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was nearly recovered. Dentin bridges were observed in 2 out of 6 cases treated with Ca(OH)2. 42 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was totally recovered. Dentin bridges were observed in 2 out of 7 cases of pulp treated with FS and four out of 6 cases treated with Ca(OH)2. 63 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was soundly resumed. The dentine bridge was observed in 4 out 6 cases of pulp treated with the FS and in all 6 cases treated with Ca(OH)2.

CONCLUSION

FS has no dentin inducing activity, but can enhance exposed pulp healing, so FS can be served as a promised pulp capping agent.

Thrombogenic effects of a nonthrombin-based fibrin sealant compared with thrombin-based fibrin sealant on microvenous anastomoses in a rat model

The efficacy and safety of tissue adhesives needs to be clearly defined. A thrombin-based preparation of fibrin sealant has recently been shown to have deleterious effects on microvascular anastomoses in an animal model. The authors found that fibrin sealant constructed with a high concentration of bovine thrombin (1,000 IU per milliliter) was detrimental to microvascular patency when applied to the anastomosis in a rat free flap model. The microvenous anastomosis had the highest rate of thrombosis and failure in this model. A nonthrombin-based fibrin sealant has recently become available for experimental investigation. This study examined the thrombogenic effect of this nonthrombin-based fibrin sealant on microvenous anastomoses in a rat free flap model compared with the effect of traditionally prepared fibrin sealant with varying concentrations of thrombin. The conclusions reveal that flap survival with application of the nonthrombin-based fibrin sealant to the anastomosis was comparable with flap survival of the control animals. Flap survival with application of the traditionally prepared thrombin-based fibrin sealant was also comparable with flap survival of the control animals when a concentration of 500 IU per milliliter of thrombin was used. However, flap survival decreased significantly (p <0.005) when a concentration of 1,000 IU per milliliter of thrombin was used in the construct of the fibrin adhesive. These results support the previous findings of the harmful effects of thrombin when used in high concentrations and applied to the microvenous anastomosis of this free flap model. Moreover, this initial investigation with a nonthrombin-based fibrin sealant did not show any deleterious effects on the microvenous anastomosis compared with control animals.

An evaluation of fibrin tissue adhesive concentration and application thickness on skin graft survival

OBJECTIVES

To examine the effects of fibrinogen concentration and application thickness of fibrin tissue adhesive on skin graft survival.

STUDY DESIGN

Prospective controlled study.

METHODS

Ten domestic pigs were included in the study. A 20 x 5-cm area of skin was harvested bilaterally along the flanks of the animals using a Padgett dermatome. The harvested grafts were trimmed into four 4 x 4-cm squares. Donor sites were treated according to group assignment and the non-meshed grafts were placed on the side opposite their initial orientation and secured with staples. Both single- and multiple-donor human fibrin tissue adhesive preparations, with low and high average fibrinogen concentrations of 30 mg/mL and 60 mg/ mL, were used. Adhesive preparations were applied in either a thin layer (0.015 mL/cm2) or a thick layer (0.06 mL/cm2) using a spray applicator. A constant thrombin concentration of 10 U/mL was used in the study. No adhesive was used in the control group and grafts were stabilized with staples. No topical dressings were applied to any of the treatment sites. Animals were sacrificed 4 weeks after graft application.

RESULTS

Based on statistical analysis, thickness of adhesive application had a significant effect on skin graft survival. Percent mean graft survival in the control and thin application groups was found to be 92% and 97.8% respectively; the mean survival rate in the thick application group was 63.1%. Fibrinogen concentration, when evaluated independently within the thin and thick application groups, was found to have no significant effect on graft survival.

CONCLUSION

Independent of fibrinogen concentration, a thin layer of fibrin tissue adhesive, when applied between two opposing surfaces, does not interfere with and may support the healing process, whereas a thick layer of adhesive inhibits skin graft healing.

Effect of fibrin glue on small and large bowel anastomoses in the rat

Fibrin glue has been used as a hemostatic and adhesive agent for many years, but its efficacy in digestive surgery is still controversial. In this study, we evaluated the effect of fibrin glue on the healing of the small and large bowel anastomotic portions by measurement of the anastomotic bursting pressure. Further, the efficacy of fibrin glue in preventing intra-abdominal adhesion formation was assessed. Our results indicated that fibrin glue enhanced the resistance towards an elevation of intraluminal pressure in small bowel, but not in large bowel. Concomitantly, the glue did not significantly attenuate postoperative adhesion formation. A sealing action of fibrin glue might protect against bleeding and microleakage, resulting in beneficial effects on small bowel anastomosis.