Sealing effect of rapidly curable gelatin-poly (L-glutamic acid) hydrogel glue on lung air leak

BACKGROUND

Air leak is a problem commonly occurring in lung and thoracic operations. In this study, a rapidly curable hydrogel glue was prepared as the seal for lung air leak.

METHODS

Mixing an aqueous solution of gelatin and poly(L-glutamic acid) with a water-soluble carbodiimide produced a hydrogel. The sealing effect on the air leak wound of rat lung was compared with that of conventional fibrin glue.

RESULTS

The gelatin-poly(L-glutamic acid) hydrogel glue was solidified as rapidly as the fibrin glue, and was significantly more effective in sealing the lung air leak than the fibrin glue. Approximately 80% of the lungs treated with the hydrogel glue exhibited no air leak at the lung pressure of 50 cm H2O. Urea addition could prevent spontaneous gelatination of the mixed solution at room temperature and did not affect the hydrogel sealing effect. The bonding strength of the hydrogel glue both with and without urea to the lung tissue was significantly higher than that of the fibrin glue.

CONCLUSIONS

We concluded that this strong lung adhesion of the gelatin-poly(L-glutamic acid) hydrogel glue resulted in its superior sealing effect.

Neovascularization effect of biodegradable gelatin microspheres incorporating basic fibroblast growth factor

Biodegradable microspheres were prepared through glutaraldehyde cross-linking of gelatin without using any surfactants as a carrier matrix of basic fibroblast growth factor (bFGF). In the in vitro system, bFGF was sorbed to microspheres of acidic gelatin with an isoelectric point (IEP) of 5.0, but not to those of basic gelatin with an IEP of 9.0. The rate of bFGF sorption to the acidic gelatin microsphere in phosphate-buffered saline solution (pH 7.4) was smaller than that in water. Following incorporation of bFGF into the microspheres at 4 degrees C for 12 h, bFGF release from the bFGF-incorporating microspheres was studied. Approximately 30% of incorporated bFGF was released from the acidic gelatin microsphere within the initial 3 h, followed by no substantial release, whereas the basic gelatin microsphere released almost completely the incorporated bFGF within 1 day. It is likely that when basic bFGF molecules were immobilized to the acidic gelatin constituting microspheres through polyion complexation, they were not readily released under the in vitro nondegradation condition of gelatin. Incorporation of anionic carboxylmethyl cellulose (CMC) into the acidic gelatin microspheres reduced the amount of bFGF desorbed initially. This indicates that the initial burst is ascribed to free bFGF which is not ionically interacted with the acidic gelatin. CMC will function as a bFGF sorbent to suppress the initial leakage from the microspheres. When injected subcutaneously into the mouse back, bFGF-incorporating acidic gelatin microspheres were degraded over time and induced neovascularization around the injection site, in marked contrast to bFGF in the solution form. CMC incorporation slowed down the biodegradation and vascularization effect of bFGF-incorporating gelatin microspheres. It was concluded that the gelatin microsphere was a promising carrier matrix of bFGF to enhance the vascularization effect.

Non-suture end-to-end anastomoses between polytetrafluoroethylene graft and vessels for blood access

BACKGROUND

Non-suture end-to-end anastomoses between polytetrafluoroethylene grafts and blood vessels were achieved using absorbable cuff material in experimental and clinical studies. The cuff was made of a synthetic biodegradable material, a lactic-glycolic acid copolymer, similar in composition to conventional absorbable surgical sutures.

METHODS

In the experimental study, vascular anastomoses for prosthetic interposition of the infrarenal aorta in rabbits were created using the cuff method. Six months after surgery, the cuff anastomoses sites were examined angiographically and microscopically and found to be patent and smooth without neointimal hyperplasia.

RESULTS

The cuff layer had been completely absorbed. The clinical application used a similar technique and involved the creation of forearm bridge graft fistula in twelve patients for hemodialysis. In eight patients, Doppler fistula flow rate ranged from 167 ml/min to 392 ml/min. Ten of the twelve patients continued dialysis uneventfully. The one-year patency rate was 78% (7/9). The longest patency period was 920 days and the graft access continued to maintain sufficient blood flow for hemodialysis.

CONCLUSIONS

This absorbable cuff material is therefore well suited for the construction of prosthetic vascular end-to-end anastomoses.

Simple mixing of IFN with a polysaccharide having high liver affinity enables IFN to target to the liver

Interferon (IFN) therapy is only one method that is clinically effective in controlling disease activity in patients with chronic hepatitis. A chelating residue (diethylenetriamine pentaacetic acid, DTPA) was introduced to pullulan, which is a polysaccharide with high liver affinity. This DTPA-pullulan could conjugate with IFN through Zn2+ coordination on mixing these three components. Intravenous injection of the IFN-DTPA-pullulan conjugate with Zn2+ coordination induced activity in the liver of an antiviral enzyme. 2',5'-oligoadenylate synthetase at IFN doses lower than those used for free IFN injection. In addition, synthetase induction by the conjugate continued for a longer time than did induction by free IFN. Liver targeting of IFN by this conjugation technique based on Zn2+ coordination opens a new method of IFN therapy.

Cellular response in subretinal neovascularization induced by bFGF-impregnated microspheres

PURPOSE

To determine the sequence of cellular changes associated with a new rabbit model of subretinal neovascularization (SRN) induced by subretinal injection of basic fibroblast growth factor (bFGF)-impregnated microspheres.

METHODS

bFGF-impregnated gelatin microspheres, prepared by forming a polyion complex between gelatin and bFGF, were subretinally implanted into rabbit eyes. The eyes were studied by immunochemistry at 3 days to 8 weeks after implantation. Antibodies to CD4, CD8, cytokeratin, CD31, glial fibrillary acidic protein (GFAP), and RAM11 were used.

RESULTS

Cytokeratin-positive retinal pigment epithelial (RPE) cells appeared on day 3 and continued to increase in number in the subretinal space throughout the growth of the SRN membrane, becoming the predominant cell type. Macrophages (RAM11-positive) appeared early, but most disappeared within 7 days. GFAP-positive Müller cells were evident early in the retina but migrated into the subretinal space after 7 days; the gliotic adhesion they formed between the retina and the SRN membrane was prominent at 8 weeks. CD31-positive endothelial cells were first evident at 14 days and formed neovascular channels that were still present for up to 8 weeks. CD4- and CD8-positive lymphocytes appeared in the early stages but were few in number.

CONCLUSIONS

SRN membranes are primarily composed of RPE cells and vascular endothelial cells. The membrane adheres to the retina by a gliotic band. The cellular components involved in the membrane of this model resemble those found in SRN membranes removed from patients with age-related macular degeneration.

Marrow cell culture on poly-L-lactic acid fabrics

Bone marrow cells from rat femurs were cultured in Eagle Minimum Essential Medium containing 15% fetal calf serum until confluence. After the cells were trypsinized, they were subcultured on fabrics made of biodegradable poly-L-lactic acid for 2 weeks in the medium containing fetal calf serum, ascorbic acid phosphate, beta-glycerophosphate, and with and without dexamethasone. In the presence of dexamethasone, the fabrics showed many mineralized nodules together with cuboidal shaped cells that had osteoblastic activity, as evidenced by high alkaline phosphatase activity and the appearance of osteocalcin messenger ribonucleic acid. However, in the absence of dexamethasone, nodules did not form and many fibroblastic cells appeared with no evidence of osteoblastic activity. These results indicate the possibility of making a hybrid ligament substitute having an in vitro prefabricated bone anchor.

Characterization and transplantation of agarose microencapsulated canine islets of Langerhans

The bioartificial pancreas was designed to incorporate islet tissues and a selectively permiable membrane that isolates islets from the immune system of the recipient. The efficacy of agarose, a nontoxic polysaccharide, has been evaluated as a material of microcapsules to prevent allo- and xenograft rejection in rodents. The aim of this study is to demonstrate the possibility of the agarose microcapsule containing allo-islets as a bioartificial pancreas in canine model. In vitro viability of islets was determined by glucose challenge during perifusion experiments (n = 4). Insulin secretion from both encapsulated (enc.) and non-encapsulated (non-enc.) canine islets rose from initial basal levels of 0.09 (encap.), 0.07 (non-encap.) to the peak of 0.2 (encap.), 0.1 (non-encap.) in microU/islet/min after 5 minutes, then decreased to the basal level when the glucose challenge was discontinued. Auto-transplantation was performed in two dogs to evaluated in vivo viability and biocompatibility of encapsulated islets implanted into the splenic sinus by venouse reflux. Two weeks after auto-transplantation, the plasma insulin levels in the splenic vein and artery of two dogs were assayed. In the first dog, serum insulin level was 1 microU/ml both in the vein and the artery and increased, after glucagon (1.0 mg) injection, to levels of 9 microU/ml in the vein, but still kept 1 microU/ml in artery, as well as in the second one. Histological and electron-microscopical examination of the spleen revealed that encapsulated islets remained morphologically intact and the surface of agarose capsules showed no significant adherence of fibroblasts and inflammatory cells. Functional efficacy of the microencapsulated islets was determined using five totally-pancreatectomized diabetic dogs as recipients without immunosuppression. Defined quantity of microencapsulated islets from outbred mongrel donors were grafted through the catheter into omental tissue of the pancreatectomized recipients. All dogs had various degrees of reduced insulin requirements. In three of five recipients, the average fasting glucose values were controlled under 120 mg/dl for 28, 42, 49 days without exogenous insulin, which received totally 4.3 x 10(3), 7.3 x 10(3) and 1.0 x 10(4) (IE/kg) of microencapsulated islets, respectively. In conclusion, the present study indicates that the agarose-based microencapsulated islets can function in large diabetic animals, resulting in the independence of exogenous insulin therapy for prolonged periods without the need for immunosuppression.

Biodegradation and tumorigenicity of implanted plates made from a copolymer of epsilon-caprolactone and L-lactide in rat

Flat plates made from a copolymer of epsilon-caprolactone and L-lactide (P-CL-LA) [50:50 (w/w), molecular weight 1.62 x 10(5); 20 x 10 x 1 mm size] were subcutaneously implanted into 50 young, male Wistar rats (P-CL-LA group). After 24 months the plates had become a mass of small pieces, which were concentrated in an area of 3 x 2 x 1 mm. For comparison, 50 rats were implanted with medical-grade polyethylene plates (PE group) while another set of 50 rats was subjected to the same operation but without an implant (Sham Op group). Tumors arose in 25 rats from the P-CL-LA group: 24 were malignant mesenchymal tumors at the implant sites. In the PE group, tumors appeared in 16 rats (14 at the implant sites and two ectopically). The average tumor latency was 578+/-84 days in the P-CL-LA group and 452+/-102 days in the PE group. There was no difference in tumor incidence between the P-CL-LA and PE groups (p < 0.05). In the Sham Op group, two malignant tumors appeared over 2 years. Pathologically, these induced tumors arose from the inflammatory cells surrounding the degrading fragments of P-CL-LA within the tissue capsule. This indicates that relatively slowly degrading material can induce malignant tumors at a similarly high rate to nonabsorbable medical grade PE, at least in this animal model.

Growth factor release from amylopectin hydrogel based on copper coordination

This paper describes a biodegradable hydrogel matrix releasing basic fibroblast growth factor (bFGF) on the basis of protein metal coordination with the protein drug. The biodegradable hydrogel was prepared from amylopectin by its crosslinking with ethylene glycol diglycidyl ether, followed by introduction of diethylenetriaminepentaacetic acid (DTPA) residues for copper chelation. When bFGF was incorporated into the DTPA-introduced amylopectin hydrogel after chelation with Cu2+, an insignificant amount of bFGF was released from the hydrogel in buffered solution, in contrast to that without Cu2+ chelation. An increased ionic strength in the solution did not affect the bFGF release, indicating the occurrence of coordinate bonding of bFGF to the DTPA-introduced hydrogel through Cu2+ chelation. An implantation study with 125I-labeled amylopectin hydrogels demonstrated that they underwent degradation in the back subcutis of mice. Cu2+ chelation of hydrogels enabled bFGF to remain in the mouse back for a long time period, irrespective of DTPA introduction. However, DTPA residues were necessary to induce significant neovascularization by the Cu2+-chelating hydrogels incorporating bFGF. The DTPA-introduced amylopectin prevented Cu2+-induced deactivation of bFGF, again in marked contrast to DTPA-free amylopectin. It was concluded that biologically active bFGF could be incorporated to DTPA-introduced amylopectin through Cu2+ chelation in a stabilized state and was released as a result of hydrogel biodegradation, resulting in prolonged neovascularization.

Assessment of heat and storage conditions on gamma-ray and electron beam irradiated UHMWPE by electron spin resonance

Electron spin resonance (ESR) spectroscopic study was undertaken to explore the nature of any remaining radicals in ultra-high molecular weight polyethylene (UHMWPE) after irradiation with gamma-rays and electron beams to a dose of 25 KGy in air or N2 environment. The decay of radicals was studied by observing the ESR intensity change as a function of time. The following post-irradiation conditions were employed: (1) storage in air or N2 at 25 degrees C, and (2) heat treatment in air or N2 at 80, 100, and 120 degrees C for time intervals up to 8 h. The study suggests that radicals remaining trapped in the matrix of UHMWPE could be dramatically scavenged by heat treatment, independently of the atmosphere during irradiation and the heating process. The melting temperature and mechanical properties of irradiated UHMWPE under the experimental conditions employed were shown not to alter significantly by heat treatment, except in the presence of air.

Effect of additives on gelation and tissue adhesion of gelatin-poly(L-glutamic acid) mixture

Gelation and tissue adhesion of mixtures of gelatin and poly (L-glutamic acid) (PLGA) aqueous solution were investigated in the presence of additives following the addition of a water-soluble carbodiimide (WSC) that induced chemical cross linking between gelatin and PLGA. To prevent spontaneous gelation of the mixed solution through physical cross linking between gelatin molecules at room temperature, additives were added to the mixed solution. Among the additives studied, starch and urea were effective in preventing the spontaneous physical gelation. The mixed gelatin and PLGA solution set to a cross-linked hydrogel within scores of second by WSC addition, irrespective of the presence of urea, whereas the viscosity of the solution with added starch was too high to measure the gelation time. The cross-linked gelatin-PLGA hydrogels with and without urea showed higher bonding strength to soft tissues than fibrin glue. This was in marked contrast to gelatin-PLGA hydrogels with soluble starch. Irrespective of the presence of urea, the gelatin-PLGA hydrogels gradually biodegraded in the back subcutis of mice over 3 months and no severe inflammatory response to the hydrogels was observed. These findings indicate that urea is promising as an additive to prevent spontaneous physical gelation of the mixed gelatin and PLGA aqueous solution without changing the characteristics of WSC-induced cross linking and tissue adhesion of the formed hydrogel.

Detection of cracks in polyethylene components of retrieved knee joint prostheses

Subsurface cracks that had formed in polyethylene artificial knee components were observed nondestructively with a new method, scanning acoustic tomography (SAT). Standardization of the SAT observation was done by in-vitro rolling fatigue testing on an unimplanted ultra high molecular weight polyethylene (UHMWPE) knee component. Retrieved knee components were of two types; KOM (Kyocera, Kyoto, Japan) sterilized with ethylene oxide gas, and MG (Zimmer, IN, USA) sterilized with gamma-irradiation. The SAT images revealed cracks in all the retrieved components, and these existed mainly 0. 3-1.0 mm from the surface. Comparison of crack formation in each portion of the contact area of the polyethylene components showed that the middle portion of the MG type had the highest concentration of cracks. When the distribution of compressive stress on the polyethylene components was assessed by mechanical testing, the strongest compressive stress was seen in the middle portion of MG type components.

Application of biomedical engineering to neurosurgery

Biomedical engineering is increasingly becoming very important also in neurosurgery. This article describes some examples of neurosurgical applications of biomaterials which play a central role in biomedical engineering. Since a large number of biomaterials are currently used in neurosurgery, only the biomaterials that have been developed in our laboratories in collaboration with neurosurgeons are briefly presented here. The biomaterials developed include devices used for interventional neurosurgery and bioabsorbable scaffolds for regeneration of dura mater and skull bone. We developed an immediately electrically detachable coil using a poly(vinyl alcohol) junction between the coil and the delivery wire. This is the first detachable coil developed in Japan and is currently under clinical trial. In addition to the coil used for interventional neurosurgery, the development of an embolic liquid is presented. As an alternative to allografts such as Lyodura, we developed a dural substitute from synthetic bioabsorbable polymers which are completely free from potential risk of latent virus infection. Finally, our experience in tissue engineering for skull bone regeneration using growth factors coupled with polymeric carriers is presented to demonstrate the promise of tissue engineering in the future.

Hemostatic capability of rapidly curable glues from gelatin, poly(L-glutamic acid), and carbodiimide

The hemostatic capability of rapidly curable glues composed of gelatin and poly(L-glutamic acid) (PLGA) was compared with that of the conventional fibrin glue. The hydrogels produced from mixed gelatin and PLGA aqueous solution within several seconds by addition of water-soluble carbodiimide (WSC) was applied to the dog spleen injured by needle pricking. The WSC-catalyzed gelatin-PLGA glues exhibited higher hemostatic capability than the fibrin glue. The total amount of bleeding from the injured spleen until hemostasis when the gelatin-PLGA hydrogel glues were applied was significantly smaller than that of the fibrin glue application. The gelatin-PLGA glue application enhanced the success rate of complete hemostasis to a significantly greater extent than the fibrin glue, while the frequency of glue applications until achieving complete hemostasis decreased. The gelatin PLGA hydrogels strongly adhered to the surface of dog spleen, whereas the fibrin hydrogel was easily detached from the spleen surface. It was concluded that this strong adhesion mechanically suppressed the bleeding, leading to enhanced hemostasis by the rapidly curable gelatin-PLGA glues.

A novel surgical glue composed of gelatin and N-hydroxysuccinimide activated poly(L-glutamic acid): Part 1. Synthesis of activated poly(L-glutamic acid) and its gelation with gelatin

Although fibrin glue has been widely used as a surgical adhesive, its components, fibrinogen and thrombin, obtained from human blood are not completely free from the risk of virus infection due to acquired immune deficiency and hepatitis. Recently, we have reported that a polymer pair composed of gelatin and poly(L-glutamic acid) (PLGA) promptly forms a gel and can firmly bond to soft tissues when crosslinked with the aid of water-soluble carbodiimide (WSC). The present study was undertaken to design a new PLGA-gelatin glue without using WSC. Two kinds of PLGA with molecular weights of 71 and 22 kDa were employed to prepare N-hydroxysuccinimide (NHS) activated derivatives. The NHS-activated PLGA could be synthesized at high yields and was found to be stable for an extended time without losing the ability to crosslink with gelatin when stored under a dry-cold condition. This NHS-activated PLGA could spontaneously form a gel with gelatin in an aqueous solution within a short time, comparable to a commercial fibrin glue, when gelation was allowed to proceed at pH 8.3. The NHS-activated PLGA prepared from PLGA with the molecular weight of 22 kDa could be readily dissolved at high concentrations and its ability to form a gel was maintained for more than 10 min when an acidic 8% NHS-activated PLGA solution was used. The bonding strength of PLGA gelatin glues with natural tissue was higher than that of fibrin glue. These findings strongly suggest that this combination of gelatin and NHS-PLGA is very promising as a surgical adhesive and may possibly replace fibrin glues prepared from human blood components.

Histologic findings in polyacrylamide-coated polytetrafluoroethylene (PTFE) arterial grafts in the rat abdominal aorta

To improve cell attachment without inducing thrombogenesis, the authors coated the inner surface of polytetrafluoroethylene (PTFE) prostheses (I.D.: 1 mm; length: 10 mm; wall thickness: 0.5 mm; fibril length: 30 microm) with polyacrylamide (PAA), known to have a strong antithrombotic effect (PAA-PTFE). They implanted the prostheses into the abdominal aorta of rats, and retrieved them at intervals of up to 9 months. Graft healing was observed under light and scanning electron microscopy. All the inner surfaces of the grafts examined were barely covered with fibrin or platelets. The PAA-coated fibers had many projections, in contrast to the original PTFE prostheses. Neo-endothelium was observed to be directly attached to these structural fibers of the PAA-PTFE grafts. Restoration of the neointima was also observed in these vascular prostheses.

In vitro sorption and desorption of basic fibroblast growth factor from biodegradable hydrogels

In vitro interaction of basic fibroblast growth factor (bFGF) with biodegradable gelatin hydrogels was investigated, focusing on its sorption into the hydrogels and desorption from them. Basic bFGF was sorbed to the hydrogel of acidic gelatin with an isoelectric point (IEP) of 5.0 over time at 4 degrees C, in contrast to that of basic gelatin with an IEP of 9.0 and type I collagen. The bFGF sorption was almost independent of the sorption temperature except for 4 degrees C and the hydrogel water content. Fluorescent microscopic observation revealed that bFGF was sorbed into the interior of the acidic gelatin hydrogel. The binding molar ratio of bFGF to the acidic gelatin was around 1.0. The bFGF sorption to the acidic gelatin hydrogel increased when gelatin was further carboxylated. bFGF was sorbed into the acidic gelatin hydrogel more slowly than into the poly(acrylic acid) (PAAc) hydrogel, probably because of the lower density of negative charge of gelatin. The bFGF sorption decreased with an increase in solution ionic strength, indicating that an electrostatic interaction was the main driving force for bFGF sorption to the acidic gelatin hydrogel. However, even at higher ionic strengths of solution, the sorbed bFGF was not desorbed from the acidic gelatin hydrogel, in contrast to the PAAc hydrogel.

Comparison of bone regeneration in a rabbit skull defect by recombinant human BMP-2 incorporated in biodegradable hydrogel and in solution

The objective of this study is to compare bone regeneration induced by recombinant human bone morphogenetic protein-2 (rhBMP-2) incorporated into a biodegradable gelatin hydrogel with that by rhBMP-2 in aqueous solution. After treating rabbit skull defects of 6 mm diameter with the two rhBMP-2 dosage forms, both of them increased the bone mineral density (BMD) at the skull defects with implantation time to a significantly higher extent than a rhBMP-2-free aqueous solution and a rhBMP-2-free empty gelatin hydrogel (p < 0.05). There was no quantifiable difference in BMD between the two dosage forms of rhBMP-2. Histological examination revealed that the integrity of newly generated bone increased with the rhBMP-2 dose, irrespective of the dosage form. The bone defect was filled with regenerated bone 21 days after treatment.

Effects of static magnetic field on bone formation of rat femurs

Effects of static magnetic fields (SMF) on bone formation of rat femurs, were evaluated using tapered rods made of magnetized and unmagnetized samarium cobalt of the same size. They were implanted transcortically into the middle diaphysis of rat femurs under press-fit loading. The bone mineral density (BMD) and bone calcium content were measured 12 weeks after implantation by dual-energy X-ray absorptiometry and chemical analysis with o-cresolphthalein complexon, respectively. The result revealed that the femurs adjacent to magnetized specimens had significantly higher BMD and calcium content than those adjacent to the unmagnetized specimen (p < 0.01). However, the value of BMD and calcium content of rats with magnetized specimens was similar to that of non-operated rats. No specific change was found in the body weight, serum Ca, activity of alkaline phosphatase, hemogram, and BMD of the tibia and humerus among the magnetized and unmagnetized. These results suggest that the long-term local SMF stimulation on the bone has a local effect to prevent the decrease in BMD caused by surgical invasion or implantation.

Ectopic bone formation induced by biodegradable hydrogels incorporating bone morphogenetic protein

Biodegradable hydrogels were prepared from gelatin by glutaraldehyde cross-linking for release matrix of recombinant human bone morphogenetic protein-2 (BMP-2). BMP-2 solution was impregnated into the dried hydrogels to prepare BMP-2-incorporating gelatin hydrogels. In the in vitro study, enhanced retention of BMP-2 was observed from the BMP-2-incorporating gelatin hydrogels after an initial burst of BMP-2 incorporated initially in the hydrogel. Following subcutaneous implantation of (125)I-labeled BMP-2-incorporating gelatin hydrogels in the back of mice, the radioactivity remaining in the hydrogels was measured to estimate the in vivo release profile of BMP-2. It was found that BMP-2 was retained in the hydrogels for longer than 30 days, whereas 99% of BMP-2 injected in the solution form was cleared from the injected site within one day, completely disappearing within 3 days. Ectopic bone formation studies demonstrated that BMP-2-incorporating gelatin hydrogels exhibited a more potent ability for bone induction than solution injection of BMP-2. This finding indicates that enhanced retention of BMP-2 is promotes its ability to induce ectopic bone formation.

Complexation of basic fibroblast growth factor with gelatin

Polyion complexation between basic fibroblast growth factor (bFGF) and gelatin was studied by the turbidity change of mixed solution, heparin high performance liquid affinity chromatography (HPLAC), and isoelectric electrophoresis. When an aqueous solution of acidic gelatin with an isoelectric point (IEP) of 5.0 was mixed with that of bFGF, the turbidity of the mixed solution increased with time, whereas basic gelatin with and IEP of 9.0 did not cause any solution turbidity. A maximum turbidity of the mixed bFGF and acidic gelatin solution was observed around a bFGF/gelatin molar ratio of 1.0, irrespective of the gelatin concentration and solution temperature. The solution turbidity decreased with an increase in the ionic strength of the mixed solution. Complexation of bFGF with acidic gelatin was slower than that with poly(acrylic acid) probably because of the lower density of gelatin negative charge than that of poly(acrylic acid). HPLAC study revealed that complexation of bFGF with the acidic gelatin reduced the affinity of bFGF for heparin, in contrast to the basic gelatin, although the extent became smaller with the increasing ionic strength of the solution. An electrophoretic experiment showed that the IEP of bFGF shifted to a lower value after its gelatin complexation. These findings indicate that an electrostatic interaction is the main driving force for the complexation between acidic gelatin and basic bFGF.

Experimental and clinical evaluation of cisplatin-containing microspheres as intraperitoneal chemotherapy for ovarian cancer

BACKGROUND

We aimed to evaluate the in vitro and in vivo effects of poly [L-lactic acid] microsphere containing cisplatin (CDDP-MS) for intraperitoneal (i.p.) chemotherapy for ovarian cancer.

METHODS

We initially examined the in vitro and in vivo profile of cisplatin release from the CDDP-MS, then this drug delivery system was evaluated in 15 patients.

RESULTS

The in vitro study showed that cisplatin was released constantly over a 3-week period. Rats in the CDDP-MS group had a significantly lower peak serum concentration of platinum compared with rats in the aqueous cisplatin solution (CDDP-S) group; the serum concentration of platinum showed a gradual decline. The ascitic fluid concentration of platinum also gradually decreased in the CDDP-MS group. We treated 15 patients with recurrent ovarian cancer with CDDP-MS containing 200 mg of cisplatin (n = 5) or CDDP-S containing 100 mg of cisplatin (n = 10) administered i.p. The peak serum and ascites concentrations of platinum were lower immediately after administration of CDDP-MS than after administration of CDDP-S, but increased over time in the CDDP-MS group, reflecting the slow-release effect of CDDP-MS. Grade 1 to 2 leukopenia and/or neutropenia occurred in 2 of 5 patients. No thrombocytopenia or renal or neurologic toxicity was observed;

CONCLUSION

These findings indicate that the i.p. administration of CDDP-MS increased the dose intensity of cisplatin and appeared to be safe and effective for the treatment of ovarian cancer.