[Preparation and biological characteristics of a new doxorubicin-gelatin-microspheres for hepatic artery embolization].

OBJECTIVE: To prepare a new doxorubicin-gelatin-microspheres (DR-GMs) suitable for hepatic artery chemoembolization. METHODS: Oxidized dextran and glutaraldehyde were used respectively as crosslinking agent for preparing DR-GMs. Orthogonal design was employed to optimize the preparation of the oxidized dextran cross-linked GMs. The morphology, swelling, and in vitro and in vivo degrading were compared between the two groups of microspheres, both with 60% degree of cross-linking. RESULTS: The granulometers of both groups of microspheres fitted for hepatic artery embolization. The roundness of the microspheres (observed with scanning electron microscope) crosslinked by oxidized-dextran was better than those crosslinked by glutaraldehyde. The microspheres crosslinked by oxidized-dextran had an average diameter of (78.2 +/- 8.1) microm, and a narrow size distribution (76.4 +/- 3.2)%, which ranged from 50 to 125 microm. The drug content rate and encapsulation rate of the microspheres crosslinked by oxidized-dextran were (87.5 +/- 0.9)% and (12.2 +/- 1.1)% respectively, higher than those crosslinked by glutaraldehyde (P < 0.01). The cumulative release rate of doxorubicin from the microspheres crosslinked by oxidized-dextran in 12 hours was 83.2%, lower than that from the microspheres crosslinked by glutaraldehyde (P < 0.01). The in vitro and in vivo studies found that the duration of degradation of the microspheres crosslinked by oxidized-dextran appeared longer than those crosslinked by glutaraldehyde. CONCLUSION: Oxidized-dextran is a better crosslinking agent for preparing DR-GMs, because it has more advantages over glutaraldehyde as for hepatic artery chemoembolization.

Modification of the method to establish a hepatic VX2 carcinoma model in rabbits.

The hepatic VX2 carcinoma model in rabbits is widely used for the preclinical study of hepatocellular carcinoma. In the present study, a modification was made to the conventional method to establish the animal model, as the conventional method gives rise to frequent tumor seeding due to the drop-out of tumor fragments. In order to evaluate each distinct method of establishing the model, the rabbits were divided into two groups: Group A (the conventional method; n=20) and group B (the modified method; n=20). All surgical details were recorded for reference. At 14 days post-surgery, contrast-enhanced computed tomography (CECT) and autopsy were conducted. Microscopic morphology of tumor cells was observed using hematoxylin and eosin (H&E) and transmission electron microscopy (TEM). Vascular endothelial growth factor (VEGF) and cluster of differentiation (CD)31 were detected via immunochemistry and reverse transcription-polymerase chain reaction. In total, 19 rabbits in each group succeeded in model establishment. Throughout the surgery, group A experienced a longer surgery time compared with group B (group A vs. group B, 22.57±1.34 vs. 20.17±1.50 min; P<0.001), an increased tumor fragment drop-out frequency (group A vs. group B, 1.84±0.96 vs. 1.16±0.38; P=0.008) and an increased peritoneal nodule incidence (group A vs. group B, 35 vs. 5%, P=0.042). As for CECT, H&E and TEM, hepatic VX2 allografts in the two groups demonstrated similar imaging presentations and tumor cell morphology. In addition, VEGF and CD31 levels did not differ between the two groups. In conclusion, the modified method for the establishment of hepatic VX2 carcinoma model in rabbits may decrease tumor fragment drop-out frequency during surgery and incidence of tumor seeding without affecting the properties of VX2 carcinoma.

In vivo distribution of (131)I and (125)I dual-labeled gelatin microspheres after implantation into rabbit liver.

OBJECTIVE: The purpose of this study was to explore the radionuclide distribution and metabolism of (131)I and (125)I dual-labeled gelatin microspheres ((131)I-(125)I-GMSs) implanted in rabbit liver. METHODS: The simultaneous radiolabeling of (131)I and (125)I into GMSs was performed by a chloramine-T method to prepare biodegradable dual-labeled radionuclide microspheres. The microspheres were injected into rabbit liver. Radionuclide distribution and metabolism in vivo were examined using single photon emission computed tomography (SPECT) and by blood and urine radioactivity counting. RESULTS: (131)I and (125)I were labeled into the biodegradable GMSs in accordance with the mixture ratio of batch feeding. After (131)I-(125)I-GMSs had been implanted in rabbit liver, small amounts of (131)I and (125)I were released into the blood along with the degradation of microspheres and excreted via the urine within 24 days. The radionuclides in the rabbit liver injection site could be detected by SPECT until day 48. The microspheres could be observed by histological methods on day 32. No signs of thyroid damage were observed throughout the entire experimental period. CONCLUSION: (131)I-(125)I-GMS can be retained long term in the injection site. Due to the advantages of combining two radionuclides, (131)I-(125)I-GMS may be a safe and effective choice for cancer brachytherapy.

Direct in vivo injection of 131I-GMS and its distribution and excretion in rabbit.

AIM: To explore the distribution and metabolism of (131)I-gelatin microspheres ((131)I-GMSs) in rabbits after direct injection into rabbits' livers. METHODS: Twenty-eight healthy New Zealand rabbits were divided into seven groups, with four rabbits per group. Each rabbit's hepatic lobes were directly injected with 41.336 +/- 5.106 MBq (131)I-GMSs. Each day after (131)I-GMSs administration, 4 rabbits were randomly selected, and 250 microL of serum was collected for gamma count. Hepatic and thyroid functions were tested on days 1, 4, 8, 16, 24, 32, 48 and 64 after (131)I-GMSs administration. Single-photon emission computed tomography (SPECT) was taken for each group on days 0, 1, 4, 8, 16, 24, 32, 48, 64 after (131)I-GMSs administration. A group of rabbits were sacrificed respectively on days 1, 4, 16, 24, 32, 48, 64 after (131)I-GMSs administration. Their livers were taken out for histological examination. RESULTS: After (131)I-GMSs administration, the nuclide was collected in the hepatic area with microspheres. The radiation could be detected on day 48 after (131)I-GMSs administration, and radiography could be seen in thyroid areas in SPECT on days 4, 8, 16 and 24. One day after (131)I-GMSs administration, the liver function was damaged but recovered 4 d later. Eight days after (131)I-GMSs administration, the levels of free triiodothyronine and free thyroxin were reduced, which restored to normal levels on day 16. Histological examination showed that the microspheres were degraded to different degrees at 24, 32 and 48 d after (131)I-GMSs administration. The surrounding parts of injection points were in fibrous sheathing. No microspheres were detected in histological examination on day 64 after (131)I-GMSs administration. CONCLUSION: Direct in vivo injection of (131)I-GMSs is safe in rabbits. It may be a promising method for treatment of malignant tumors.

Effect of 5-FU on modulation of disarrangement of immune-associated cytokines in experimental acute pancreatitis.

AIM: To investigate the effects of 5-Fluorouracil (5-FU) on modulation of pro-inflammatory and anti-inflammatory cytokines in acute pancreatitis and the mechanism of it in the treatment of acute pancreatitis. METHODS: Male Sprague Dawley rats were assigned to 3 Groups: Group A, sham operated rats as controls (n = 7); Group B, acute pancreatitis induced by ductal injection with 5% sodium cholate at a volume of 1.0 mL/kg without any other treatment; Group C, after the pancreatitis was induced as in Group B, the rats were injected intravenously with 5-FU 40 mg/kg. The animals in Groups B and C were killed at 2, 6 and 24 h after operation (n = 7), and blood samples were taken for measurement of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), interleukin-6 (IL-6) (by bioassay), and interleukin-10 (IL-10), transforming growth factor-beta (TGF-beta) (by ELISA). The wet weight of pancreatic tissue, serum amylase levels and white blood cells were also measured. RESULTS: Four rats in Group B and one in Group C died after pancreatitis was induced. Both pro-inflammatory cytokines (TNF-alpha, IL-1, IL-6) at the 2 and 6 h period and the anti-inflammatory cytokines (IL-10, TGF-beta) at 24 h increased significantly (P < 0.05) in rats of Group B. After treatment with 5-FU, TNF-alpha, IL-1, and IL-6 in serum of rats of Group C were inhibited at 2 and 6 h after operation (P < 0.05), and IL-10, TGF-beta were inhibited at 24 h compared to Group B (P < 0.05). Obvious improvements in the severity of the acute pancreatitis, including the amylase levels, wet weight of pancreatic tissue and neutrophil counts, were also observed after treatment with 5-FU. CONCLUSION: 5-FU is an anti-metabolic and immunosuppressive agent which can minimize the abnormal immune cytokine response and relieve the pathophysiological disorders associated with experimental acute pancreatitis.