A technique for isolation perfusion of the canine liver with survival

Tumor necrosis factor-alpha augments tumor effects in isolated hepatic perfusion with melphalan in a rat sarcoma model

Isolated hepatic perfusion (IHP) is an attractive approach to treating nonresectable liver tumors, because the effects of systemic chemotherapy are poor and its application is hampered by severe general toxicity. In clinical and experimental settings, the efficacy of isolated limb perfusion (ILP) with tumor necrosis factor-alpha (TNF alpha) in combination with melphalan to treat melanoma in transit and soft-tissue sarcoma has been well established. In an ILP model in rats, the authors previously observed synergistic anti-tumor effects of TNF and melphalan on BN 175 soft-tissue sarcoma extremity tumors. The aim of the current study was to determine whether similar synergy in anti-tumor effects could be achieved by treating experimental BN 175 soft-tissue sarcoma liver tumors by IHP using these agents. The authors found that IHP with TNF and melphalan resulted in a dramatic increase in regional concentrations of perfused agents with virtually no concomitant systemic leakage. Isolated hepatic perfusion with only carrier solution resulted in a significantly diminished growth rate of BN 175 liver tumors compared with the growth rate of tumors in nonperfused rats. Perfusion with melphalan alone resulted in minimal anti-tumor effects. Perfusion with only TNF had a slight growth-stimulatory effect on the BN 175 liver tumors, but no negative effects on tumor growth were observed. When TNF was added to melphalan, a dramatic anti-tumor effect was observed. Thus, as in the rat ILP setting, the anti-tumor effect is augmented when TNF is added to IHP with melphalan to treat BN 175 soft-tissue sarcoma tumor-bearing rats. Strikingly, the tumor response was potentiated at relatively low concentrations of TNF compared with concentrations that elicited synergy with melphalan in ILP.

Isolated hepatic perfusion for lapine liver metastases: impact of hyperthermia on permeability of tumor neovasculature

BACKGROUND

Hyperthermic isolated hepatic perfusion (IHP) has been shown to cause significant regression of advanced unresectable liver metastases in patients. Although there are different agents and treatment modalities used in IHP, the contribution of perfusion hyperthermia is unknown.

PURPOSE

A large animal model of unresectable liver metastases and a technical standard for IHP in this model were established. This model was used to assess the effects of hyperthermia on vascular permeability of tumors and normal liver tissue during IHP.

METHODS

Sixty-five New Zealand White rabbits were used in a series of experiments. Disseminated liver tumors were established by direct injection of 1 x 10(6) VX-2 cells into the portal vein by laparotomy in anesthetized animals. Several surgical perfusion techniques were explored to determine a reliable and reproducible IHP model. Vascular permeability in tumor versus liver was then assessed with Evan's Blue labeled bovine albumin under normothermic (tissue temperature 36.5 degrees C +/- 0.5 degree C), moderate hyperthermic (39 degrees C +/- 0.5 degree C), or severe hyperthermic (41 degrees C +/- 0.5 degree C) conditions.

RESULTS

Tumor model and perfusion techniques were successfully established with inflow through the portal vein and outflow through an isolated segment of the inferior vena cava. A gravity driven perfusion circuit with stable perfusion parameters and complete vascular isolation was used. Vascular permeability was higher in tumor than in normal tissues (P = .03) at all time points during IHP. Hyperthermia resulted in a significant (up to 5-fold) increase in permeability of neovasculature; when severe hyperthermia was used, tumor vascular permeability was increased even more than normal liver permeability (P = .01).

CONCLUSIONS

The VX-2/New Zealand White rabbit system can be used as a reproducible large-animal model for IHP of unresectable liver metastases. It can be used to characterize the contribution and mechanism of action of different treatment parameters used in IHP. Hyperthermia preferentially increases vascular permeability in tumors compared with liver tissue in a dose-dependent fashion, thus providing a mechanism for its presumed benefit during isolated organ perfusion.

Isolated hypoxic hepatic perfusion with tumor necrosis factor-alpha, melphalan, and mitomycin C using balloon catheter techniques: a pharmacokinetic study in pigs

OBJECTIVE

To validate the methodology of isolated hypoxic hepatic perfusion (IHHP) using balloon catheter techniques and to gain insight into the distribution of tumor necrosis factor-alpha (TNF), melphalan, and mitomycin C (MMC) through the regional and systemic blood compartments when applying these techniques.

SUMMARY BACKGROUND DATA

There is no standard treatment for unresectable liver tumors. Clinical results of isolated limb perfusion with high-dose TNF and melphalan for the treatment of melanoma and sarcoma have been promising, and attempts have been made to extrapolate this success to the isolated liver perfusion setting. The magnitude and toxicity of the surgical procedure, however, have limited clinical applicability.

METHODS

Pigs underwent IHHP with TNF, melphalan, and MMC using balloon catheters or served as controls, receiving equivalent dosages of these agents intravenously. After a 20-minute perfusion, a washout procedure was performed for 10 minutes, after which isolation was terminated. Throughout the procedure and afterward, blood samples were obtained from the hepatic and systemic blood compartments and concentrations of perfused agents were determined.

RESULTS

During perfusion, locoregional plasma drug concentrations were 20- to 40-fold higher than systemic concentrations. Compared with systemic concentrations after intravenous administration, regional concentrations during IHHP were up to 10-fold higher. Regional MMC and melphalan levels steadily declined during perfusion, indicating rapid uptake by the liver tissue; minimal systemic concentrations indicated virtually no leakage to the systemic blood compartment. During isolation, concentrations of TNF in the perfusate declined only slightly, indicating limited uptake by the liver tissue; no leakage of TNF to the systemic circulation was observed. After termination of isolation, systemic TNF levels showed only a minor transient elevation, indicating that the washout procedure at the end of the perfusions was fully effective.

CONCLUSIONS

Complete isolation of the hepatic vascular bed can be accomplished when performing IHHP using this balloon catheter technique. Thus, as in extremities, an ideal leakage-free perfusion of the liver can now be performed, and repeated, without major surgery. The effective washout allows the addition of TNF in this setting.

A porcine model for investigation of hyperthermic isolated liver perfusion

Our study was aimed at developing a reliable method of hyperthermic isolated liver perfusion (HILP) in pigs and at assessing its local and systemic side effects. HILP was performed via the hepatic artery and portal vein in 15 animals. The perfusate consisted of blood (200 ml), oxypolygelatine (500 ml), Ringer's solution (1000 ml), and trapped intrahepatic blood. HILP was carried out for 45 min at a mean perfusate inflow temperature of 41.2 degrees C. The mean portal flow and pressure were adjusted to 500 ml/min and 20-25 mm Hg; the mean arterial flow and pressure were 130 ml/min and 40-60 mm Hg, respectively. After 20 min of perfusion the mean temperature in the right and the left liver lobe were 40.8 degrees C and 40.3 degrees C and remained almost constant over the whole perfusion period. Liver enzymes (alanine aminotransferase and aspartate aminotransferase) and serum lactate levels showed slight increases after perfusion but normalized within 1 week. Histology of liver parenchyma showed only mild pathological changes, which were also reversible within 7 days. The presented method of HILP is a safe and reproducible technique for isolated hyperthermic liver perfusion. Based on this animal model, experimental HILP with different chemotherapeutic agents can be investigated in order to assess hepatic and systemic toxicity of this therapy.

Isolated hepatic perfusion with tumor necrosis factor alpha and melphalan: experimental studies in pigs and phase I data from humans

We report our experience with isolated hepatic perfusion (IHP) with tumor necrosis factor (TNF) and melphalan in an experimental pig study and of a phase I study in humans. IHP was performed with inflow catheters in the hepatic artery and portal vein and an outflow catheter in eh caval vein. An extracorporeal venovenous bypass was used. IHP consisted of a 60-min perfusion with hyperthermia (> 41 degrees C). For the pig protocol rhTNF alpha 50 micrograms/kg alone (n = 5) or rhTNF alpha 50 micrograms/kg plus melphalan 1 mg/kg (n = 3) were added. In two control pigs no drugs were added. In the phase I study, patients received melphalan 1 mg/kg with 0.4 mg rhTNF alpha (n = 8) or 0.8 mg rhTNF alpha (n = 1). After the perfusion the liver was washed with Macrodex before vascular continuity was restored. All pigs but one survived the procedure. Systemic leakage was less than 0.02%. Transient, mild liver toxicity was seen in all pigs, including controls, as demonstrated by liver enzyme assays and histology. There was no significant hemodynamic, cardiopulmonary hematological, or renal toxicity. In the phase I clinical study there was leakage in one patient (cumulative leakage 20%). There were three perioperative deaths (one possibly drug-related). All patients demonstrated significant hepatotoxicity. Survival ranged from 6 to 26 months (median 10.3 months). All patients demonstrated a tumor response (partial response 5/6, 1/6 stable disease) with a median duration of 18 weeks. In contrast to our pig program, many problems were encountered in the phase I study. By using both the hepatic artery and portal vein for IHP we encountered more toxicity than expected based on data from the pig program, resulting in fatal coagulative disturbances in one patient who received the second rhTNF alpha dose. Furthermore, local control after one IHP with TNF alpha and melphalan is only temporary.

Biochemical and morphological changes in the liver during isolated liver perfusion with double bypass using automatic blood pumps

Isolated organ perfusion is used in clinical practice for chemotherapy in adults with malignant tumors. However, it has not been performed in children because of the size mismatch with the adult circuits. The authors have previously studied isolated liver perfusion in small animals using the self-regulating extracorporeal membrane oxygenation circuit. The present study was designed to investigate the biochemical and morphological changes in the liver during isolated liver perfusion with double bypass using automatic blood pumps. Isolated liver perfusion was performed with bypass between the hepatic and portal veins in seven weanling Yorkshire swine weighing 8.2 to 12.2 kg, at a flow rate of 20 mL/min/kg for up to 4 hours. Venous blood from the intestine and lower body was bypassed to the superior vena cava. As a result, perfusate glutamic pyruvic transaminase and lactate concentrations did not change during liver perfusion. On gross inspection, the surface of the liver was mottled. Microscopically, normal histology of the hepatic parenchyma and portal tract structures was preserved. Transmission electron microscopy showed no gross structural abnormalities in most of the hepatocytes for up to 4 hours. However, swelling of the mitochondria and smooth endoplasmic reticulum was seen occasionally in a very small number of the hepatocytes after more than 3 hours of perfusion. Glycogen granules decreased with time in some animals. Isolated liver perfusion at 20 mL/min/kg of perfusion flow can be performed safely for up to 4 hours with nearly intact hepatocellular function and morphology.

Development of an isolated perfusion circuit with double bypass using automatic blood pumps

Isolated perfusion of the liver is a useful and promising therapeutic method for various hepatic diseases. However, conventional techniques using a roller pump require a large priming volume and cannot run at the low flow rate without complications. These disadvantages do not allow the use of conventional techniques in smaller pediatric patients. The authors solved these problems successfully for the first time by using unique sac-type air-driven automatic blood pumps with an oxygenator primed with a blood volume of 65 ml in the total circuit. The usefulness of these blood pumps for liver perfusion was evaluated in small animals weighing 3.5-6.0 kg. A hepatic perfusion circuit was established between the portal vein and the inferior vena cava. The blood pumps worked well without any trouble, and stable flow could be maintained. No hepatocellular damage or anaerobiosis of the liver was observed at a hepatic perfusion flow rate of 20 ml/min/kg. Isolated liver perfusion using these blood pumps can be applied in infants and young children.

An evaluation of hepatic extraction and clearance of doxorubicin

A swine model was developed to study quantitatively the pharmacokinetics of hepatic extraction and clearance of doxorubicin (DOX). Systemic and hepatic artery infusions of DOX (0.5-9 mg kg-1) were administered to 34 pigs. Pharmacokinetic analysis was simplified by use of a double-balloon catheter in the inferior vena cava to collect hepatic venous effluent. During hepatic artery infusion only, DOX in hepatic venous blood was extracted using activated carbon filters to prevent drug recirculation. Hepatic extraction and clearance of DOX were independent of dose and route of administration. Extraction ratios varied from 0.75 to 0.91 during hepatic artery infusion and from 0.50 to 0.72 during systemic infusion. Clearance results were analogous. After cessation of drug infusions, hepatic extraction and clearance of DOX was negative, suggesting that the liver serves as a drug reservoir during DOX infusion and subsequently is a net source of unmetabolised drug. Liver extraction and clearance of DOX in pigs are substantial. During either systemic or hepatic artery infusion of DOX, the liver serves as a drug reservoir. Subsequent mobilisation of this hepatic pool of DOX may cause prolonged systemic exposure to drug.

Simple method of hyperthermo-chemo-hypoxic isolated liver perfusion for hepatic metastases

As a regional therapy for hepatic malignancy, we developed a simple method of isolated liver perfusion (hyperthermo-chemo-hypoxic). In the present study, the influence of this method on the hepatic tissue and other organs was experimentally evaluated and applied it to seven patients. Experimentally, all dogs survived without hepatic insufficiency and systemic toxicity. Clinically, one patient died on postoperative day 14 of hepatic failure. The reason was that liver temperature reached 43 degrees C, which seemed to be the maximum limit for thermal toxic effect to the human liver. The other six patients well tolerated the perfusion with mild increases of serum aminotransferase and total bilirubin levels and decreases of hepaprastin levels. Serum aminotransferase and total bilirubin and hepaprastin levels returned to normal levels by postoperative day 14. There were no significant differences between the isolated liver perfusion group (n = 7) and hepatectomy-only group (n = 27). Six patients were disease-free during the observation period after the perfusion. This system is a simple, useful method for treating patients with metastatic cancer limited to the liver.

A model for directed foreign gene delivery to rat liver cells in vivo

A novel technique for directed delivery of retroviral genes to rat liver cells in vivo is described. Vascular isolation of the liver was achieved in situ and perfusate containing retrovirus expressing the bacterial gene conferring resistance to Hygromycin-B was delivered selectively to the posterior liver lobes. After 15 min, normal blood flow to the liver was restored. The portal venous branch supplying the two anterior liver lobes was ligated either at the same time (Group I, n = 4) or 20 hr prior to perfusion (Group II, n = 4) to stimulate DNA synthesis in the posterior lobes. Controls (Group III, n = 4) were perfused with retrovirus without portal branch ligation. Hepatocyte transduction was assessed 7 days later by isolating the cells and assessing their viability in a selection medium. In Group I and II rats, 9.2 +/- 0.5 and 16.0 +/- 1.0%, respectively, of harvested hepatocytes, expressed the Hygromycin-B gene. In contrast, a significantly smaller number of hepatocytes (2.8 +/- 0.9%, P less than 0.003) expressed the gene in the absence of stimulation of DNA synthesis.

Increasing the effective concentration of melphalan in experimental rat liver tumours: comparison of isolated liver perfusion and hepatic artery infusion

Regional chemotherapy allows further exploitation of the steep dose response curve of most chemotherapeutic agents, while systemic toxicity remains tolerable. We investigated the difference in maximally tolerated dose, pharmacokinetics and antitumour effect comparing administration of melphalan as a bolus in isolated liver perfusion (ILP) or via hepatic artery infusion (HAI). For these in vivo studies an experimental model for liver metastases in male WAG/Ola rats is obtained by subcapsular inoculation of CC531 rat colon carcinoma cells. In this system, ILP allowed administration of a two times higher dose than HAI (12 mg kg-1 vs 6 mg kg-1). In both treatment modalities systemic toxicity (leukopenia) was dose limiting. No hepatic toxicity was observed. Bolus administration of the maximally tolerated doses of melphalan in HAI (6 mg kg-1) and ILP (12 mg kg-1) resulted in four times higher concentrations in both liver and tumour tissue of the ILP treated rats. However, the ratio of mean drug concentration in liver vs tumour tissue appeared to be 1.5 times that found for HAI. In the range of the in tumour tissue measured melphalan concentrations the CC531 cells showed a steep dose response relationship in vitro. Whereas HAI resulted in significant tumour growth delay, complete remissions were observed in 90% of the rats treated with ILP. This study shows that with 12 mg kg-1 melphalan in ILP highly effective drug concentrations are achieved in CC531 tumour tissue; although the melphalan concentration in liver tissue shows an even higher increase than in tumour tissue, hepatic toxicity is negligible in this dose range.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study of isolated liver perfusion versus hepatic artery infusion with mitomycin C in rats

Systemic toxicity is usually the dose-limiting factor in cancer chemotherapy. Regional chemotherapy is therefore an attractive strategy in the treatment of liver metastasis. Two ways of regional chemotherapy, hepatic artery infusion (HAI) and isolated liver perfusion (ILP), were compared investigating the difference in toxicity with tissue and biofluid concentrations of mitomycin C (MMC). In wistar derived WAG rats the maximally tolerated dose of mitomycin C via HAI was 1.2 mg kg-1. Body weight measurements after HAI with doses higher than 1.2 mg kg-1 suggest both an acute and delayed toxic effect of mitomycin C since the time weight curves were triphasic: a rapid weight loss, a steady state and a second fall in weight phase. These rats died due to systemic toxicity. ILP with 4.8 mg kg-1 was associated with no signs of systemic toxicity and only transient mild hepatotoxicity. ILP with 6.0 mg kg-1 was fatal mainly due to hepatic toxicity. The four times higher maximally tolerated dose in ILP resulted in a 4-5 times higher peak concentration of mitomycin C in liver tissue, while the plasma concentration remained significantly lower than in the HAI treated rats. In the tumour tissue a 500% higher concentration of mitomycin C was measured in the ILP with 4.8 mg kg-1 than in HAI with 1.2 mg kg-1 treated rats. We demonstrated that when mitomycin C was administered by ILP a 400% higher dose could be safely administered and resulted in a five times higher tumour tissue concentration. In view of the steep dose-response curve of this alkylating agent this opens new perspectives for the treatment of liver metastasis.

In vivo isolated liver perfusion technique in a rat hepatic metastasis model: 5-fluorouracil concentrations in tumor tissue

An in vivo method of isolated rat liver perfusion was developed with true vascular isolation and recirculating perfusate. This new surgical technique to temporarily isolate the liver vascularly, and the perfusion procedure are described in depth. Twelve inbred WAG/RIJ rats were subjected to 25 min of normothermic liver perfusion without chemotherapy, and all rats survived the procedure. Hepatic functional and histological integrity were not significantly altered during perfusion. To determine the role of isolated liver perfusion (ILP) as a means of improved targeting of antitumor agents, 5-fluorouracil (5-FU) concentrations were monitored in hepatic tumor and liver tissues and in systemic plasma using high-performance liquid chromatography. Fifty-one rats with hepatic tumors of colonic origin were randomly assigned to one of three dosage groups (20, 40, or 80 mg/kg) receiving 5-FU by ILP, hepatic artery infusion (HAI), or jugular vein infusion (JVI). ILP resulted in significantly increased 5-FU concentrations in liver tissue. However, no significant differences were found in tumor tissue concentrations of 5-FU between the three treatment modalities. 5-FU concentrations in tumor tissue increased as a function of the dose with ILP, HAI, and JVI. ILP was associated with the lowest systemic drug concentrations. The low systemic 5-FU concentrations with ILP suggest a higher maximum tolerable dose. This mode of treatment deserves to be studied further in our model before conclusions can be drawn regarding its therapeutic potential.

A successful technique of in vivo isolated liver perfusion in pigs

A technique was developed to isolate the hepatic circulation from the general circulation using a double lumen intracaval shunt. Low flow normothermic perfusion of the liver was performed for 1 hr 25 min in pigs. All pigs survived the procedure. The isolated liver perfusion without chemotherapy (n = 11) was well tolerated as monitored by hepatic enzymes and histologic examination during and after the operation. Mild transient elevations of SGOT and LDH returned to normal values within 1 week. No significant pathological alterations were found in the liver biopsies. Twenty-two pigs were subjected to isolated liver perfusion with 20, 40, or 80 mg 5-FU/kg. Up to four times the conventional dose of the drug could safely be administered when a washout was performed. To evaluate the efficacy of the isolation a method for leakage detection was developed, using tracer quantities of 99mTc-labeled red blood cells. This method was sensitive and permitted continuous monitoring of leakage. Negligible leakage was found during 15 isolated liver perfusions. The described technique of isolated liver perfusion was a reliable and technically feasible method, and has been adapted for clinical use to evaluate its value in the treatment of hepatic metastases.

Alterations in biochemical functions during hyperthermic isolation-perfusion of the human liver

Hyperthermia (42-42.5 degrees) was applied to the liver of eight patients with cancer in the liver by a technique of isolation-perfusion. Hepatic functional integrity was assessed during perfusion through measurement of multiple perfusate constituents. Data from seven perfusions were available for analysis. During perfusion there was an increase in perfusate lactate, pyruvate, glucose, urea, potassium, alkaline phosphatase, SGOT, and LDH. All increases in these constituents were significant (P less than 0.05) except for potassium. Lactate accumulated throughout the perfusion from an initial level of 3.8 +/- 1.0 mM to 7.6 +/- 3.5 mM at 4 hr. Pyruvate increased over the first 3 hr of perfusion from 0.14 +/- 0.06 mM to 0.80 +/- 0.37 mM before declining to 0.54 +/- 0.24 mM at 4 hr. The L/P (lactate/pyruvate) ratio decreased during perfusion to less than 10 in the first 2 hr, but rose to within normal limits by the end of perfusion. The decreases in L/P ratios were significant (P less than 0.05). Initially there was a rapid rise in perfusate glucose concentrations from 4.5 +/- 0.8 mM to 20.7 +/- 5.4 mM at 2 hr with nonsignificant changes thereafter. Urea levels increased from 0.64 +/- 0.22 mM to 1.92 +/- 0.76 mM. Perfusate potassium increased from the initial level of 7.0 +/- 1.0 mM during perfusion to 8.3 +/- 1.7 mM at 2 hr before declining. SGOT, LDH, and alkaline phosphatase increased during perfusion from 21 +/- 15, 142 +/- 48, and 16 +/- 6 to 176 +/- 22, 472 +/- 53 and 52 +/- 42, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation-perfusion of the liver with 5-fluorouracil

Isolation-perfusion of the liver was performed in ten pigs using 5-fluorouracil administered in the perfusion circuit at doses of 100, 250, 500, and 1000 mg/kg body weight. Perfusion was performed for 60 minutes at normothermic (37 C) or hyperthermic (41 C) temperatures. One animal died shortly after perfusion. Incomplete isolation of the hepatic vasculature in two animals resulted in significant drug leakage into the systemic circulation with resulting hematologic toxicity. Perfusion with 5-fluorouracil at 1000 mg/kg produced hepatic necrosis. Perfusion with 5-fluorouracil at doses of 100, 250, or 500 mg/kg produced no hepatic toxicity except for transient elevations of hepatic enzymes and resulted in no systemic drug toxicity. Levels of 5-fluorouracil tolerated by the liver in the isolation-perfusion system were more than 1000-fold greater than the maximum drug levels achievable by routine systemic, intra-arterial, or intraperitoneal administration.

A technique for isolated hyperthermic liver perfusion

Hyperthermia, either alone or combined with chemotherapy, has been shown to be effective in treating cancer. Because some investigators believe that regional hyperthermia may be more effective than whole body hyperthermia, we developed a technique to heat only the liver to 42-43 degrees for 4 hr. The procedure was adapted from a previously described animal model and was performed in four humans. Vascular isolation of the liver was accomplished by cannulating the hepatic artery, the portal vein, and the inferior vena cava followed by occluding the suprahepatic vena cava and the liver was then perfused with blood and nutrients from an oxygenated reservoir. Preliminary results show radiologic and histologic evidence of tumor necrosis or cessation of tumor growth in three of the patients. We believe this technique is safe enough for clinical experimental use and deserves further investigation.

Effects of hyperthermia on plasma glycoprotein catabolism by the isolated perfused rat liver

Clearance and degradation of the glycoprotein, asialofetuin (AF), by the isolated perfused rat liver at supranormal temperatures were investigated. The half-life for disappearance of AF was similar at 37, 41, and 42 degrees C, P greater than 0.05. There was a significant difference between the amount of hydrolysis of AF at 37, 41, and 42 degrees C, P less than 0.05. This indicates that there was significant retardation of lysosomal proteolysis or receptor endocytosis by the hepatocyte at elevated temperatures.