Shuko Suzuki

Biomaterials for surgical operation

Biomaterials for surgical operation / , Biomaterials for surgical operation / , کتابخانه دیجیتال جندی شاپور اهواز

Gelatin gel as a carrier of platelet-derived growth factors

Currently, patient’s own growth factors from platelet-rich plasma and platelet-rich fibrin have been clinically used for repair and regeneration of defective tissues. In platelet-rich plasma and platelet-rich fibrin, fibrin gel is formed from blood fibrinogen and functions as a carrier for growth factors. In this study, the growth factors were extracted from the platelet-rich fibrin and incorporated into a gelatin gel by mixing the platelet-rich fibrin extract and gelatin solution before cross-linking with glutaraldehyde. About 70% of TGF-β1 was found to be released in vitro from the gelatin gel containing the platelet-rich fibrin extract into phosphate-buffered saline (–) in 7 days. The gelatin gel containing basic fibroblast growth factor, prepared as a comparison, showed a similar release profile. The gelatin gels were slowly degraded with time after subcutaneous implantation on the back of rats, and the gel containing the platelet-rich fibrin extract strongly induced neovascularization and granulation tissue formation around the implantation site compared to the gel only and the gel containing basic fibroblast growth factor, platelet-rich plasma, or platelet-rich fibrin. The gelatin gel containing the platelet-rich fibrin extract was attempted as wound dressing on a full-thickness skin defect model. After 2 weeks of application, the gel was found to be more effective in acceleration of wound healing than the commonly used platelet-rich plasma.

The anti-adhesive effect of thermally cross-linked gelatin film and its influence on the intestinal anastomosis in canine models.

To generate a more effective and safer anti-adhesive material, we have developed a new type of thermally cross-linked gelatin film. In this study, we preclinically examined the anti-adhesive efficacy of this film and evaluated the possibility applying the film safely onto fresh intestinal anastomoses, compared with hyaluronate and carboxymethyl-cellulose (HA/CMC) film. Using a canine adhesion model, the degree of adhesion for each film was evaluated by adhesion scoring systems and histological observation. Three weeks after surgery, only the gelatin film showed significantly superior anti-adhesive effects compared to the control (no treatment), in particular, exhibiting excellent re-peritonization. Next, in a canine anastomosis model, the anastomoses were wrapped directly by each film and the bursting pressures of the anastomoses were examined 3 and 7 days after surgery. The gelatin film did not significantly affect either the bursting pressures or the healing process, compared with the control. However, the HA/CMC film significantly decreased the bursting pressures measured at 3 days after surgery. In conclusion, the thermally cross-linked gelatin film had satisfactory anti-adhesive effects with excellent re-peritonization. It could be safely applied to intestinal anastomoses without decreasing the bursting pressures. The gelatin film is considered to be quite favorable as an anti-adhesive material.

Sealing effects of cross-linked gelatin.

Surgical sealants form gel when applied to tissues. Currently, fibrin sealant has been successfully used in many surgical fields, but it has several disadvantages, including possible virus transmission, low adhesive strength, and high cost. In this study, gelatin and glutaraldehyde (GA) solutions were chosen to demonstrate the effectiveness of cross-linked gelatin gel as sealant and barrier, both of which have long been used in medical applications. It was found that the gelatin gel prepared from 26 wt% gelatin and 1 wt% GA solutions exhibited bonding strength almost three times higher than that of fibrin glue. The bonding strength increased with the increasing gelatin and GA concentrations. When a needle hole on PTFE vascular grafts was sealed with the gelatin gel, the water-resistant pressure significantly increased upon rubbing and was twice higher than that of fibrin glue. The cytotoxicity of gelatin gel was found to be much lower than that of albumin glue prepared at the same composition as commercially available BioGlue®. The gelatin gel was found to be also effective as barrier to prevent adhesion in a rat cecum abrasion model.

Effectiveness of a new gelatin sealant system for dural closure

Abstract Objectives: Watertight dural closure is imperative after neurosurgical procedures because inadequately treated leakage of cerebrospinal fluid (CSF) can have serious consequences. In this study, the authors test the use of a new gelatin glue as a dural sealant in in vitro and in vivo canine models of transdural CSF leakage. Methods: The in vitro model was sutured semicircles of canine dura mater and artificial dural substitute. The sutures were sealed with gelatin glue (n  =  20), fibrin glue (n  =  20), or a polyethylene glycol (PEG)-based hydrogel sealant (n  =  20). Each sample was set in a device to measure water pressure, and pressure was increased until leakage occurred. Bonding strength was subjectively evaluated. The in vivo model was dogs who underwent dural excision and received either no sealant (control group; n  =  5) or gelatin glue sealant (n  =  5) before dural closure. Twenty-eight days post-surgery, the maximum intracranial pressure was measured at the cisterna magna using Valsalva maneuver and tissue adhesion was evaluated. Results: The water pressure at which leakage occurred in the in vitro model was higher with gelatin glue (76·5 ± 39·8 mmHg) than with fibrin glue (38·3 ± 27·4 mmHg, P < 0·001) or the PEG-based hydrogel sealant (46·3 ± 20·9 mmHg, P  =  0·007). Bonding strength was higher for the gelatin glue than fibrin glue (P < 0·001) or PEG-based hydrogel sealant (P  =  0·001). The maximum intracranial pressure in the in vivo model was higher for the gelatin glue group (59·0 ± 2·2 mmHg) than the control group (13·8 ± 4·0 mmHg, P < 0·001). Tissue adhesion was lower for the gelatin glue group than the control group (P  =  0·005). Discussion: The new gelatin glue provides an effective watertight closure when used as an adjunct to sutured dural repair.

Biological properties of a thermally crosslinked gelatin film as a novel anti-adhesive material: Relationship between the biological properties and the extent of thermal crosslinking

In order to prevent postoperative adhesion and the related complications, a thermally crosslinked gelatin (TCG) film was developed and the basic biological properties were examined, paying special attention to the relationship between these properties and the extent of crosslinking of the film. The gelatin films crosslinked thermally for five different time periods (0, 1, 3, 8, and 14 hours) were developed and the following tests were performed. Regarding the material characterization of the films, the water content, the water solubility, and the enzymatic degradation for collagenase were found to be closely related to the duration of thermal crosslinking. In an in vitro study conducted to examine the cell growth of fibroblasts cultured on the films, the degree of cell growth, except no crosslinked film, was less than that observed in the control group, thus suggesting that such effects of the films on fibroblast cell growth may be related with their anti-adhesive effects. In in vivo tests, the films crosslinked for longer time periods (3, 8, and 14 hours) were retained for longer after being implanted into the abdominal cavity in rats and showed a significant anti-adhesive effect in the rat cecum adhesion models, indicating that the biodegradability and anti-adhesive effects of the TCG films depend on the duration of thermal crosslinking. In order to develop useful and effective anti-adhesive gelatin film, it is very important to optimize duration of the thermal crosslinking.

Adhesion of Cells and Tissues to Bioabsorbable Polymeric Materials: Scaffolds, Surgical Tissue Adhesives and Anti-adhesive Materials

Interaction between the body and implanted materials is a very complex phenomenon, and understanding the concept of cell and tissue adhesion, which is the first event that occurs when a biomaterial is implanted, is of great importance. Currently, bioabsorbable materials are preferably used as biomaterials. They are only present in the body temporary, and promote guided cell and tissue growths for the required time. Hence, the choice of the material, depending on the application, becomes crucial. This article offers an overview of cell and tissue adhesion to three types of clinically-important bioabsorbable materials from a materials perspective: scaffolds, surgical tissue adhesives, and anti-adhesive materials.

Experimental use of crosslinked gelatin glue for arterial hemostasis in cardiovascular surgery.

BACKGROUND Anastomotic needle hole bleeding is a frequently encountered problem in cardiovascular surgeries. OBJECTIVE To examine the feasibility of crosslinked gelatin glue as an anastomotic needle hole sealant in comparison with fibrin glue. METHODS The in vitro burst water pressures were measured for gelatin and fibrin glue sealed needle holes of expanded polytetrafluoroethylene (ePTFE) or collagen coated woven polyester grafts. For in vivo investigations, abdominal aorta-ePTFE graft anastomoses of heparinized beagle dogs were sealed by gelatin or fibrin glue and hemostatic efficacy was judged. The implanted sites were re-examined 4 weeks postoperatively. RESULTS The in vitro burst water pressures of gelatin glue sealed needle holes of both grafts were higher than those sealed by fibrin glue. For in vivo canine studies, hemostasis was successful for all gelatin glue applied suture lines, but not two out of three fibrin glue treated sites when 3-0 polypropylene suture was employed. Although adhesions of surrounding tissues were intense for all sites 4 weeks postoperatively, inflammation was more severe for the fibrin glue group compared to those of gelatin glue. CONCLUSIONS Gelatin glue was found to be an effective and safe sealant for accomplishing hemostasis of anastomotic needle holes of vascular grafts.

Development of gelatin flakes, a new type of anti-adhesive material: a preliminary study of in vivo rat adhesion models

To overcome the problems associated with sheet- or film-type anti-adhesive materials, we developed a new type of anti-adhesive material, gelatin flakes. We made two types of gelatin flakes with or without thermal cross-linking, and preliminarily examined their basic properties and the anti-adhesive efficacy using a rodent adhesion model. Both types of the gelatin flakes rapidly turned into gel and tightly attached the injured surfaces, absorbing the moisture and blood, when applied onto the abraded sites of rats. In addition, these flakes could be sprayed into the desired area by compressed air through a device with a long, thin tube, which could be used in laparoscopic surgery. The anti-adhesive effects of both types of gelatin flakes were similar, and both types were significantly superior compared to the non-treated group. Although further investigations are necessary, the gelatin flakes have unique and useful properties and satisfactory anti-adhesive effects, which indicate that they may be applicable in laparoscopic surgery.

Usefulness of a New Gelatin Glue Sealant System for Dural Closure in a Rat Durotomy Model

Watertight dural closure is imperative after neurosurgical procedures, because inadequately treated leakage of cerebrospinal fluid (CSF) can have serious consequences. We used a rat durotomy model to test the usefulness of a new gelatin glue as a dural sealant in a rat model of transdural CSF leakage. All rats were randomly divided into one of the following three treatment groups: no application (control group: N = 18), application of fibrin glue (fibrin glue group: N = 18), and application of the new gelatin glue (new gelatin glue group: N = 18). The craniotomy side was re-opened, and CSF leakage was checked and recorded at 1, 7, and 28 days postoperatively. The new gelatin glue was adequate for stopping CSF leakage; no leakage was observed at postoperative days 1 or 7, and leakage was observed in only one rat at postoperative day 28. This result was statistically significant when compared to the control group (P = 0.002, P = 0.015, P = 0.015, respectively). The pathologic score of the new gelatin group was not different from that of the control or fibrin glue groups. We conclude that our new gelatin glue provides effective watertight closure 1, 7, and 28 days after operation in the rat durotomy model.