Timothy D. Sielaff

Split Liver Transplantation for Two Adult Recipients: An Initial Experience

The shortage of cadaver donor livers has been most severe for adult patients. Split liver transplantation is one method to expand the donor pool, but to have a significant impact on the waiting list, it needs to be applied for 2 adult recipients.

Extracorporeal application of a gel-entrapment, bioartificial liver: Demonstration of drug metabolism and other biochemical functions

Metabolic activity of a gel-entrapment, hollow fiber, bioartificial liver was evaluated in vitro and during extracorporeal hemoperfusion in an anhepatic rabbit model. The bioartificial liver contained either 100 million rat hepatocytes (n = 12), fibroblasts (n = 3), or no cells (n = 7) during hemoperfusion of anhepatic rabbits. Eight other anhepatic rabbits were studied without hemoperfusion as anhepatic controls, and three sham rabbits served as normal controls. Albumin production rates (mean ± SEM) were similar during in vitro (17.0 ± 2.8 μg/h) and extracorporeal (18.0 ± 4.0 μg/h) application of the hepatocyte bioartificial liver. Exogenous glucose requirements were reduced (p < 0.01) and euglycemia was prolonged (p < 0.001) in anhepatic rabbits treated with the hepatocyte bioartificial liver. The maximum rate of glucose production by the hepatocyte bioartificial liver ranged from 50-80 μg/h. Plasma concentrations of aromatic amino acids, proline, alanine, and ammonia were normalized in anhepatic rabbits during hepatocyte hemoperfusion. Gel-entrapped hepatocytes in the bioartificial liver performed sulfation and glucuronidation of 4-methylumbelliferone. P450 activity was demonstrated during both in vitro and extracorporeal application of the BAL device by the formation of 3-hydroxy-lidocaine, the major metabolite of lidocaine biotransformation by gel-entrapped rat hepatocytes. In summary, a gel-entrapment, bioartificial liver performed multiple hepatocyte-specific functions without adverse side effects during extracorporeal application in an anhepatic, small animal model. With its potential for short term support of acute liver failure, scale-up of the current bioartificial liver device is indicated for further investigations in large animal, preclinical trials.

Local, intrahepatic, and systemic recurrence patterns after radiofrequency ablation of hepatic malignancies

The objective of this study was to describe the recurrence patterns in patients with unresectable hepatic malignancies treated with radiofrequency ablation (RFA). As RFA is applied more widely to patients with hepatic tumors, a better understanding of the biologic behavior of these tumors and the risk of recurrence, both in the liver and systemically, is needed. A multidisciplinary team evaluated patients referredh for RFA and followed them prospectively to assess local, intrahepatic, and extrahepatic disease recurrence and complication rates. Forty-five patients with 143 lesions and a minimum follow-up of 6 months (median 19.5 months) were treated. Overall, 7.7% of treated lesions had local recurrence. New intrahepatic disease was seen in 49% of patients, and 24% had evidence of new systemic tumor progression. Patients with colorectal metastatic lesions > 4 cm at the time of the first RFA were more likely to present with local recurrence (P = 0.048). Complications occurred in 27% of patients. Although RFA has a satisfactory local failure rate and safety profile, the patient population being treated is at high risk of developing new disease. Multimodality adjuvant therapy will be necessary to realize the full potential of hepatic malignancy control with RFA.

A technique for porcine hepatocyte harvest and description of differentiated metabolic functions in static culture.

Current bioartificial liver devices are based on the use of a large mass of hepatocytes exhibiting differentiated metabolic function. The pig has become a source of interest for the acquisition of such cells-however, harvesting a large mass of highly viable cells has met with difficulty. This study describes a technique for harvesting large quantities of hepatocytes at viabilities greater than 90% and also describes several features documenting differentiated function. Pigs, 6 to 10 kg body weight, underwent in situ two-step whole liver perfusion (ethylene glycol tetraacetic acid and collagenase) and ex vivo cell harvest. Harvests yielded an average of 19.5 billion cells with an average viability of 94.6%. Hepatocytes were then entrapped in type I collagen (3 x 10(5) cells/well) and cultured in serum-free media for 5 days. Pig hepatocytes produced stable amounts of albumin and maintained cytochrome P-450 and glucuronidation activity over 5 days, as shown by the metabolism of lidocaine and 4-methylumbelliferone. These data indicate that pig hepatocytes can be harvested with high yields and can retain viability and differentiated function over at least 5 days of culture, and therefore should prove to be an excellent source of hepatocytes for bioartificial liver devices.

Liver regeneration after adult living donor and deceased donor split-liver transplants.

As the number of living donor (LD) and deceased donor (DD) split‐liver transplants (SLTs) have increased over the last 5 years, so too has the interest in liver regeneration after such partial‐liver transplants. We looked at liver regeneration, as measured by computed tomography (CT) volumetrics, to see if there were significant differences among LDs, right‐lobe LD recipients, and SLT recipients. We measured liver volume at 3 months postoperatively by using CT, and we compared the result to the patients ideal liver volume (ILV), which was calculated using a standard equation. The study group consisted of 70 adult patients who either had donated their right lobe for LD transplants (n = 24) or had undergone a partial‐liver transplant (right‐lobe LD transplants, n = 24; right‐lobe SLTs, n = 11; left‐lobe SLTs, n = 11). DD (vs. LDs) were younger (P < 0.01), were heavier (P = 0.06), and had longer ischemic times (P < 0.01). At 3 months postoperatively, LDs had attained 78.6% of their ILV, less than the percentage for right‐lobe LD recipients (103.9%; P = 0.0002), right‐lobe SLT recipients (113.6%; P = 0.01), and left‐lobe SLT recipients (119.7%; P = 0.0006). When liver size at the third postoperative month was compared with the liver size immediately postoperatively, LDs had a 1.85‐fold increase. This was smaller than the increase seen in right‐lobe LD recipients (2.08‐fold), right‐lobe SLT recipients (2.17‐fold), and left‐lobe SLT recipients (2.52‐fold). In conclusion, liver regeneration, as measured by CT volume, seems to be greatest in SLT recipients. LD recipients seem to have greater liver growth than their donors. The reason for this remains unclear. (Liver Transpl 2004;10:374–378.)

Radiofrequency ablation causes 'thermal fixation' of hepatocellular carcinoma: a post-liver transplant histopathologic study.

Abstract: Radiofrequency ablation (RFA) is increasingly used to treat hepatocellular carcinoma (HCC) in patients awaiting a liver transplant. Despite its increasing use, detailed histologic information is scarce regarding the nature of RFA‐treated lesions. We identified four chronic hepatitis C patients who had RFA of their HCC before their liver transplant. For these four patients, we conducted a detailed histopathologic analysis of the treated lesions in their explanted livers. The five lesions included immediate (4 d) and long‐term (14 months) post‐RFA specimens. Of the five lesions, four were completely ablated. The one incompletely ablated lesion was also treated with chemoembolization. In the acute post‐RFA period, a zone of interstitial hemorrhage occurred at the outer boundary of the lesion. Differing from classic tissue necrosis, the treated lesions all showed ‘thermal fixation’, with preserved tissue architecture and microscopic cellular detail. The cellular staining characteristics faded with time, but the treated tissue became brittle, resisted tissue breakdown, and generated a minimal wound healing response. At the periphery of the lesion, the fibrous septae of the cirrhotic liver and vascular structures appeared to demarcate or limit progression of the ablation front. A narrow hypocellular fibrous boundary with a focal ‘foreign body’ giant cell‐type reaction developed around the edge of the ablation zone. Thus, RFA can produce immediate and complete thermal fixation of select lesions with an appropriate liver margin and can provide a satisfactory treatment option for select HCC patients before a liver transplant.

Laparoscopic stapled left lateral segment liver resection—Technique and results

Because of the favorable anatomy of the left lateral segment of the liver, a totally laparoscopic approach to resection is feasible. Herein we describe a technique for laparoscopic stapled resection of the left lateral segment of the liver, including the necessary anatomic criteria for a safe operation and data on clinical outcome. Five patients at our center underwent laparoscopic exploration, ultrasound examination, and resection of segments II and III. After complete mobilization of the left lateral segment and minimal portal dissection, the totally laparoscopic resections were performed with two endoscopic staple loads (4.5 mm Χ 60 mm) applied sequentially across the portal pedicle and the left hepatic vein. The mean operative time was 182 minutes (range 130 to 240 minutes), blood loss was 41 ml (range 25 to 50 ml), and length of hospital stay was 2.2 days (range 1 to 3 days). All three patients with malignancy had negative surgical margins. All five patients returned to normal activity or work by 1 week postoperatively. There were no complications. Patients with isolated malignant and benign diseases of the left lateral segment of the liver are candidates for totally laparoscopic resection, if evaluation demonstrates a normal liver character and hepatic parenchymal thickness less than 3 cm overlying the ligamentum venosum groove. Such patients benefit from the minimally invasive approach, with no compromise in the surgical result as compared to the open approach.

Development of a bioartificial liver employing xenogeneic hepatocytes.

Liver failure is a major cause of mortality. A bioartificial liver (BAL) employing isolated hepatocytes can potentially provide temporary support for liver failure patients. We have developed a bioartificial liver by entrapping hepatocytes in collagen loaded in the luminal side of a hollow fiber bioreactor. In the first phase of development, liver-specific metabolic activities of biosynthesis, biotransformation and conjugation were demonstrated. Subsequently anhepatic rabbits were used to show that rat hepatocytes continued to function after the BAL was linked to the test animal. For scale-up studies, a canine liver failure model was developed using D-galactosamine overdose. In order to secure a sufficient number of hepatocytes for large animal treatment, a collagenase perfusion protocol was established for harvesting porcine hepatocytes at high yield and viability. An instrumented bioreactor system, which included dissolved oxygen measurement, pH control, flow rate control, an oxygenator and two hollow fiber bioreactors in series, was used for these studies. An improved survival of dogs treated with the BAL was shown over the controls. In anticipated clinical applications, it is desirable to have the liver-specific activities in the BAL as high as possible. To that end, the possibility of employing hepatocyte spheroids was explored. These self-assembled spheroids formed from monolayer culture exhibited higher liver-specific functions and remained viable longer than hepatocytes in a monolayer. To ease the surface requirement for large-scale preparation of hepatocyte spheroids, we succeeded in inducing spheroid formation in stirred tank bioreactors for both rat and porcine hepatocytes. These spheroids formed in stirred tanks were shown to be morphologically and functionally indistinguishable from those formed from a monolayer. Collagen entrapment of these spheroids resulted in sustaining their liver-specific functions at higher levels even longer than those of spheroids maintained in suspension. For use in the BAL, a mixture of spheroids and dispersed hepatocytes was used to ensure a proper degree of collagen gel contraction. This mixture of spheroids and dispersed cells entrapped in the BAL was shown to sustain the high level of liver-specific functions. The possibility of employing such a BAL for improved clinical performance warrants further investigations.

Mycoplasma hominis Infections Occurring in Cardiovascular Surgical Patients

BACKGROUND Postoperative Mycoplasma hominis sternal would or mediastinal infections are uncommon and difficult to diagnose. Atypical growth characteristics in routine bacterial culture, and the inability to demonstrate the organism on Gram stain, lead to delayed diagnosis of M hominis infections and increased morbidity. METHODS Postoperative purulent would drainage or acute mediastinitis caused by M hominis developed in 3 cardiovascular surgery patients. These patients were considered along with 9 patients previously reported in the literature. RESULTS Operative findings included moderately thick, gray purulent fluid with the degree of tissue necrosis related to duration of infection. Intraoperative Gram stain of wound or mediastinal drainage demonstrated no microorganisms, and initial bacterial cultures did not reveal microbial growth. After an average of 4.5 days of culture, minute translucent colonies of M hominis were identified. The institution of appropriate antimycoplasma therapy (doxycycline and clindamycin) was associated with clinical or microbiological cure in all patients. Sternal wound complications developed in 3 patients, and a chronic infection developed in 1 patient. CONCLUSIONS Empiric therapy for M hominis infection should be considered in patients with mediastinitis or a sternal wound infection in which organisms are not observed on Gram stain and are not readily cultured.

Review of Support Systems Used in the Management of Fulminant Hepatic Failure

Fulminant hepatic failure has an exceedingly high mortality. Liver transplantation is the treatment option of choice. Unfortunately, one-third of patients with fulminant hepatic failure die awaiting a donor liver. For over 35 years attempts to remove or dilute putative toxins in the blood have been unsuccessful in improving survival rates. The use of biocompatible interfaces with blood or plasma and current hepatocyte culture techniques have led to the development of new support systems. This generation of bioartificial livers will hopefully provide the necessary hepatic functions and prevent many of the complications associated with fulminant hepatic failure. This paper will review the support systems tried and currently under investigation, with an emphasis on bioartificial livers.