Biomedical subjects

Peter Neuhaus

Publications and source records attributed to Peter Neuhaus.

At least 163 records · Page 9Linked to original sources

PubMed2002

Increasing applicability of liver transplantation for patients with hepatitis B-related liver disease.

Liver transplantation in patients with hepatitis B has been under discussion for 20 years because of inferior results without reinfection prophylaxis; therefore, we analyzed our overall experience with liver transplantation in hepatitis B patients with immunoprophylaxis, particularly the influence of the available antiviral treatment in different periods. From 1988 to 2000, 228 liver transplants in 206 hepatitis B patients were performed. Indications were acute liver failure (10%), hepatitis B virus (HBV) cirrhosis alone (67%) or with hepatitis D virus (HDV) (13%), or hepatitis C virus (HCV) coinfection (7%). All patients received long-term immunoprophylaxis (anti-HBs > 100 U/L). HBV DNA-positive patients were treated before and after surgery with famciclovir or lamivudine since 1993 and 1996, respectively. Since 1993, antivirals also were used for HBV reinfection. The 1-, 5-, and 10-year patient survival rates were 91%, 81%, and 73%. In patients with hepatocellular carcinoma (HCC) (60% 5-year survival, P <.01) or HBV reinfection (69% 5-year survival, P <.01) survival was significantly impaired. Those with HDV or HCV coinfection had a slightly better survival than with HBV monoinfection (P >.05, not significant). Preoperative positive HBV DNA (hybridization-assay) test results were associated with a slightly impaired patient survival (78% 5-year survival, P >.05, not significant versus DNA-negative). Preoperative positive hepatitis B e antigen (HBeAg) predicted significantly worse survival (P <.05 versus negative HBeAg). Graft loss caused by reinfection was most frequent before the availability of antiviral drugs. Two-year patient survival increased from 85% in era I (1988-1993) to 94% in era III (1997-2000, P <.05). The 2-year recurrence rates in these 2 periods were 42% and 8% (P <.05). In conclusion, excellent long-term results can be achieved in hepatitis B patients after liver transplantation with modern strategies, and survival rates are similar to other indications. Based on our experience, hepatitis B patients, including those with active viral replication, should not be excluded from liver transplantation.

Adult↗

PubMed2002

Improved treatment response with basiliximab immunoprophylaxis after liver transplantation: results from a double-blind randomized placebo-controlled trial.

Basiliximab, a high-affinity chimeric monoclonal antibody, is effective in reducing acute rejection episodes in renal allograft recipients. We assessed the ability of this antibody to similarly improve the outcome in liver transplant recipients. Adult recipients of a primary cadaveric liver transplant were randomized to treatment, stratified by hepatitis C virus (HCV) seropositivity. Patients were administered 40 mg of basiliximab (n = 188) or placebo (n = 193) as two 20-mg bolus injections days 0 and 4, plus cyclosporine and steroids. Primary efficacy variables were biopsy-confirmed acute rejection and its composite end point, including death or graft loss, and were assessed at 6 and 12 months and by HCV cohort. Because of differential efficacy responses between HCV-positive and HCV-negative cohorts, an additional analysis incorporating HCV recurrence as a component of treatment failure, termed problem-free transplant, was introduced. Safety and tolerability were monitored over the 12 months of the study. All 381 patients were assessable, and no meaningful differences in background characteristics were apparent between treatment groups. Biopsy-confirmed acute rejection rates 6 months after transplantation were 35.1% in the basiliximab group versus 43.5% in the placebo group. For death, graft loss, or first biopsy-confirmed acute rejection, rates were 44.1% versus 52.8%, respectively. The reduction in rejection episodes was concentrated in the HCV-negative cohort (14.5% relative to placebo; P =.034), with a much smaller difference (2.9%) in the HCV-positive cohort. For HCV-positive patients, problem-free transplant was shown at 12 months in 26.6% of the basiliximab group versus 11.6% in the placebo group (P =.020) and for all patients at 12 months in 39.7% of the basiliximab group versus 30.1% in the placebo group (P =.035). The incidence of infection and other adverse events was similar across the two treatment groups. There were 56 deaths (25 deaths, basiliximab group; 31 deaths, placebo group) over the 12-month study. The intravenous bolus injection was well tolerated. Immunoprophylaxis with 40 mg of basiliximab, in combination with cyclosporine and steroids, reduces the incidence of acute rejection episodes with no clinically relevant safety or tolerability concerns. The influence of HCV recurrence on efficacy results can be accounted for in future trials by using the concept of problem-free transplant, incorporating recurrence as a component of treatment failure.

Adult↗

PubMed2002

Successful hepatitis B vaccination in patients who underwent transplantation for hepatitis B virus-related cirrhosis: preliminary results.

Long-term hepatitis B immunoglobulin (HBIg) prophylaxis prevents endogenous hepatitis B virus (HBV) reinfection in the majority of liver transplant recipients. Active hepatitis B vaccination after orthotopic liver transplantation (OLT) in these patients has produced conflicting results to date. On this study, patients who remained hepatitis B surface antigen (HBsAg) negative with passive immunization after OLT for HBV cirrhosis were actively immunized using recombinant HBV antigen (Engerix), together with a novel adjuvant system (monophosphoryl lipid A and a natural saponine molecule). This led to a sustained antibody response to HBsAg (>500 IU/L) in 5 of 10 patients. This antibody response prevented reinfection and allowed termination of prophylactic HBIg substitution for more than 12 months in these patients.

Adjuvants, Immunologic↗

PubMed2002

Donor evaluation, donor risks, donor outcome, and donor quality of life in adult-to-adult living donor liver transplantation.

Right lobe living donor liver transplantation (LD-LTx) is currently performed at an increasing number of transplant centers. Donor selection, donor safety, donor recovery, and postdonation psychological impairment are essential criteria to determine whether and under which conditions LD-LTx is justifiable. Before commencing the LD-LTx program, approval was obtained from the local ethics committee. Potential donors underwent a comprehensive multistep evaluation protocol to exclude any conditions that could lead to an increased operative risk. Each donation was approved by the local Living Donation Commission. Follow-up investigations were performed after 6 and 12 months. Liver regeneration was assessed by computed tomography scan and magnetic resonance imaging scan derived volumetries. Quality of life (QOL) was investigated according to the Anamnestic Comparative Self-Assessment Scale (ACSA) before donation, and 6 and 12 months after donation. As of December 2001, 43 right lobe living donations have been performed at the Charité, Campus Virchow, Berlin. None of the donors died or has suffered life-threatening or persisting complications. All patients recovered completely. Complications occured in 8 donors (18%). The incidence of perioperative surgical complications was 9%, comprising temporary biliary leakages (n = 3; 6.8%) as well as postoperative bleeding (n = 1). Liver volume regeneration approximated 72% +/- 15% of predonation volume by 6 months and 85% +/- 18% (mean +/- SD) by 12 months. There was no evidence of significant psychological impairment after donation. QOL increased after donation compared with the preoperative state (P < .05). In our experience, LD-LTx has proven to be a practicable and safe procedure. However, there is a considerable risk of postoperative complications. The donor selection process plays a pivotal role in preventing complications. The discussion of potential risks, especially potential life-threatening risks, must be an integral part of informed consent.

Adult↗

PubMed2002

CMV hepatitis after liver transplantation: incidence, clinical course, and long-term follow-up.

Cytomegalovirus (CMV) hepatitis is described as the most frequent manifestation of CMV tissue invasive disease after liver transplantation. Its correlation with HLA-matching, hepatic artery thrombosis, and chronic rejection is still controversial. Risk factors, incidence, clinical course, and complications of CMV hepatitis were retrospectively analyzed in a 12-year series of 1,146 consecutive liver transplantations in 1,054 patients. All patients received only low-dose acyclovir but no gancyclovir prophylaxis. CMV infection was diagnosed by viral culture, pp65 antigenemia, or by polymerase chain reaction (PCR). CMV hepatitis was proven by liver biopsy. Treatment of CMV disease consisted of intravenous ganciclovir for a minimum of 14 days. Long-term follow-up of patients included monthly routine laboratory values and routine liver biopsies 1, 3 and 5 years after transplantation. CMV hepatitis was a rare event after liver transplantation, with a total incidence of 2.1% (24 cases). It was significantly more frequent in CMV seronegative (5.2%) than in seropositive recipients (0.7%). The leading indication in patients with CMV hepatitis was HCV cirrhosis (n = 8). The maximum number of pp65 positive white blood cells was 82 +/- 23 per 10,000 cells. Most courses manifested as isolated hepatitis; only 2 patients had disseminated disease. Nine of 24 patients had received OKT3 monoclonal antibodies because of steroid-resistant rejection before CMV hepatitis. In seronegative patients with CMV hepatitis, 71% revealed 1 or 2 HLA DR matches, in contrast to 32% in patients without CMV hepatitis. One-, 3-, and 5-year graft survival was 78%, 65%, and 59% in patients with CMV hepatitis compared with 88%, 81%, and 79% in patients without. Chronic rejection was observed in one patient, but already before onset of CMV hepatitis. Beneath D+R-constellation and OKT3 treatment as risk factors, HLA DR-matched grafts and HCV seem to favor manifestation of CMV hepatitis after liver transplantation. Long-term complications of CMV hepatitis were not observed, and especially no correlation with chronic rejection was found.

Acute Disease↗

PubMed2002

Genetic polymorphisms of glutathione S-transferase A1, the major glutathione S-transferase in human liver: consequences for enzyme expression and busulfan conjugation.

BACKGROUND: High-dose busulfan is widely used as part of conditioning regimens for patients who are undergoing hematopoietic stem cell or bone marrow transplantation. High plasma concentrations of busulfan have been linked to the occurrence of hepatic venoocclusive disease (VOD), a severe complication associated with a high mortality. Because conjugation with glutathione, the major route of biotransformation of busulfan, is predominantly catalyzed by the isozyme glutathione S-transferase A1 (GSTA1), we hypothesized that low expression or function of GSTA1 in liver caused by genetic polymorphisms may be the mechanism underlying VOD. METHODS: Immunoblot analysis of GSTA and measurement of busulfan-glutathione conjugation by liquid chromatography-mass spectrometry were performed in 48 normal human liver samples. To search for polymorphisms, the complete GSTA1 coding regions and the promoter fragment were sequenced. All results were compared by multivariate analysis. RESULTS: Absolute levels of GSTA protein and formation rates of busulfan-glutathione conjugate displayed a 7- and 8-fold range, from 240 to 1600 pmol/mg and 25 to 205 pmol/min per milligram of total cytosolic protein, respectively, and correlate (r2 = 0.49, P <.0001). A total of 8 single nucleotide polymorphisms (SNPs) of GSTA1 were identified, 1 of which was a silent mutation in exon 5 (A375G); all others were found in the promoter region. Haplotype analysis revealed the existence of 5 defined alleles. There was no significant relationship between any of the GSTA1 SNPs or haplotypes and either hepatic glutathione S-transferase A (GSTA) expression or GSTA1 function. CONCLUSIONS: The identified GSTA1 polymorphisms are not likely to be related to the VOD because they do not appear to be associated with changes in GSTA expression or function. Compared with other members of the GST family, GSTA1 displays surprisingly little variation.

Busulfan↗

PubMed2002

Continuation of regional chemotherapy of hepatic neoplasms despite occlusion of the hepatic artery-report of four cases.

In clinical practice, regional chemotherapy of the liver applied as 'hepatic arterial infusion' (HAI) is often limited by device dysfunction or hepatic arterial obstruction. We report the case of a patient with mixed hepato/cholangiocellular carcinoma in which HAI with folinic acid (FA) and 5-fluorouracil (5-FU) was continued after thrombotic occlusion of the A. hepatica, resulting in a flow of drugs into the V. portae (via A. lienalis and V. lienalis). By using this 'spleno-portal' access for further chemotherapy with FA/5-FU, long-term control of the patient's disease was achieved. Analyzing our experience with this and three other patients with hepatic arterial thrombosis in which we continued HAI, a total of 33 regional treatment courses were applied, containing 5-FU/FA, mitomycin C, doxorubicin or combinations of these drugs. No unexpected toxicities were observed. In addition, the clinical course of three of those four patients strongly suggests the effectiveness of this approach. Thus, our results indicate that thrombosis of the A. hepatica does not necessarily have to result in an interruption of HAI. Continuation of regional chemotherapy despite hepatic arterial occlusion preserved control of intrahepatic tumor manifestations in patients who previously responded to regular HAI.

Antimetabolites, Antineoplastic↗

PubMed2002

The marginal kidney donor.

In parallel with increased clinical demand, less than optimal or so-called marginal kidney grafts are being used for transplantation. In addition to donor age, it appears that several factors may impact negatively on the quality of the graft. Most importantly, a more precise definition of the term 'marginal graft' is needed. The present review analyzes potential risk factors, suggests scoring systems for a more precise definition, and discusses potential treatment options to improve the quality of marginal grafts.

Humans↗

PubMed2002

Interindividual variability and tissue-specificity in the expression of cytochrome P450 3A mRNA.

The elucidation of the individual contributions of the four CYP3A genes to the overall CYP3A activity has been hampered by similarities in their sequence and function. We investigated the expression of CYP3A mRNA species in the liver and in various other tissues using gene-specific TaqMan probes. CYP3A4 transcripts were the most abundant CYP3A mRNA in each of the 63 white European livers tested and accounted on average for 95% of the combined CYP3A mRNA pool. CYP3A5 and CYP3A7 each contributed on average 2%, whereas CYP3A43 contributed 0.3% transcripts to this pool. Fourteen percent of livers exhibited an increased share of CYP3A5 transcripts (range 4-20%). These livers were either heterozygous for the marker of the CYP3A5 polymorphism, the CYP3A5*1A allele, or expressed very low levels of CYP3A4 mRNA. The CYP3A7 expression was bimodal, and it was increased in 15% livers. CYP3A4 was the dominant CYP3A in the intestine, followed by CYP3A5. CYP3A5 and CYP3A7, but not CYP3A4, were also expressed in the adrenal gland and in the prostate, whereas only CYP3A5 was detected in the kidney. These three tissues were shown to express much lower levels of pregnane X receptor mRNA than the intestine, indicating possibly a different mode of regulation of CYP3A expression. Expression of CYP3A genes was undetectable in peripheral blood lymphocytes. In summary, these assays and results should aid in our efforts to further dissect the regulation and the physiological and pharmacological significance of CYP3A isozymes.

Cytochrome P-450 CYP3A↗

PubMed2002

Prospective evaluation of pancreatic tumors: accuracy of MR imaging with MR cholangiopancreatography and MR angiography.

PURPOSE: To prospectively assess accuracy of magnetic resonance (MR) imaging, MR cholangiopancreatography (MRCP), and MR angiography in patients suspected of having pancreatic tumors. MATERIALS AND METHODS: Sixty-six patients suspected of having pancreatic tumors underwent MR imaging (unenhanced and contrast material-enhanced MR, MRCP, and contrast-enhanced MR angiography). Two blinded readers prospectively analyzed the images by consensus, and results were correlated with surgery, biopsy, or follow-up findings. Results were tabulated in two-by-two tables. RESULTS: MR assessment of pancreatic lesion status (differentiation of benign vs malignant) resulted in 60 correct diagnoses (accuracy, 91%), and six (10%) false diagnoses. Among histologically proved malignant tumors, MR imaging yielded correct diagnoses in 42 of 44 patients (sensitivity, 95%; 95% CI: 85%, 99%), whereas 18 of 22 patients with benign findings were classified correctly. At MR imaging, findings in four patients with chronic pancreatitis were wrongly categorized as malignant tumors (specificity, 82%; 95% CI: 60%, 95%), and in one patient, a distal common bile duct carcinoma was not detected. In no patient with pancreatic adenocarcinoma was this tumor misdiagnosed as benign. In patients with malignant tumors who underwent resection, local-regional tumor growth and vascular infiltration were accurately classified in 89% and 94%, respectively. MR imaging depicted histologically proved synchronous hepatic metastases in 82%. The positive and negative predictive values for cancer nonresectability were 90% and 83%, respectively, and the accuracy, sensitivity, and specificity were 85%, 69%, and 95%, respectively. CONCLUSION: Unenhanced and contrast-enhanced MR imaging with MRCP and MR angiography offers potential as a noninvasive tool for assessment of patients suspected of having pancreatic tumors.

Adult↗

PubMed2002

Pituitary function test and endocrine status in patient with cirrhosis of the liver before and after hepatic transplantation.

OBJECTIVE: Hormonal alterations caused by chronic liver disease are well described. In contrast, the reversibility of peripheral hormonal changes after orthotopic liver transplantation (OLT) has only partially been analyzed since the establishment of OLT as treatment of chronic hepatic failure. In addition it is not finally verified if chronic liver failure and especially hepatic encephalopathy also affect pituitary function. We therefore performed extensive endocrine studies including a global pituitary stimulation test before and after liver transplantation. METHODS: 22 patients with chronic alcoholic and non alcoholic liver failure were included in this prospective study. Basal hormone values (ACTH, cortisol, FSH, GH, IGF-I, LH, oestradiol, PRL, thyroid hormones and testosterone) were measured before and up to 5 years after OLT. Furthermore all patients underwent pituitary function tests with application of GRF, TRH, GnRH, and CRF before, 3 weeks and 3 months after OLT. RESULTS: Estradiol, LH and FSH increased significantly in postmenopausal and only slightly in premenopausal female patients after OLT. Total testosterone revealed no marked changes and was normal before and up to five years after OLT in male patients. After stimulation with GnRH the LH response in females and the FSH response in males was significantly higher three months after OLT than pretransplant. LH response in males and FSH response in females was only slightly higher after OLT. Peripheral IGF-I was low and growth hormone was elevated in all patients prior OLT. Growth hormone declined significantly three months afterwards. The response to GRF was highest prior OLT and decreased afterwards. Prolactin values were normal prior and post OLT. After stimulation with TRH prolactin values in male patients were significantly higher before OLT than afterwards. CONCLUSION: In the observed relatively small number of patients gross pituitary function in chronic liver failure remained intact, whereas slight alterations in several axis were found. These pituitary alterations are presumably only partially caused by feedback mechanisms. Both a normalisation of peripheral endocrine parameters and pituitary function were achieved by OLT despite significant alterations pretransplant.

Adrenocorticotropic Hormone↗

PubMed2002

Kidney transplantation at the Charité: long tradition, elderly patients and the duration of hospitalization.

Since the sixties kidneys have been transplanted successfully at the 2 predecessors of today's transplant center at the Charité. So far, 1,290 kidneys were transplanted resulting in 89.8% overall graft survival at one year and 78.6% at 5 years. Several factors were associated with these results. Ischemia times were very short (11.9 +/- 7.3 hours). Patients with diabetic nephropathy were rarely transplanted without combined pancreas transplantation. Combined with a pancreas transplantation, kidney grafts fared even better than those of non-diabetic patients. The share of living donation is still rising and is associated with a better outcome than cadaveric grafts. In contrast, the effect of HLA mismatches was not very pronounced. Zero- and one-mismatch transplantations had a clear benefit over those with 2-3 mismatches, but higher numbers of mismatches did not lead to worse results. To expand the donor pool with kidneys from old donors (> 64 years) we participate in the Eurotransplant Senior Program (ESP) where these kidneys are allocated locally to recipients aged 65 years and older without HLA matching. The ischemia times for ESP kidneys were shorter (7.3 +/- 3.0 hours) but transplants were less well matched (4.2 +/- 2.1 mismatches). Graft survival was not different from controls aged 60 years and older who received a kidney from a donor under age 65. The ESP patients do not require prolonged hospitalization for transplantation (30.6 +/- 14.6 days versus 35.3 +/- 26.0 days in patients below 60 years). With the introduction of the ESP the number of transplantations in recipients aged 60 years and above have risen considerably.

Adult↗

PubMed2001

Influence of donor brain death on chronic rejection of renal transplants in rats.

The clinical observation that the results of kidney grafts from living donors (LD), regardless of relationship with the host, are consistently superior to those of cadavers suggests an effect of brain death (BD) on organ quality and function. This condition triggers a series of nonspecific inflammatory events that increase the intensity of the acute immunologic host responses after transplantation (Tx). Herein are examined the influences of this central injury on late changes in renal transplants in rats. A standardized model of BD was used. Groups included both allografts and isografts from normotensive brain dead donors and anesthetized LD. Renal function was determined every 4 wk after Tx, at which time representative grafts were examined by morphology and by reverse transcriptase-PCR. Long-term survival of brain-dead donor transplants was significantly less than LD grafts. Proteinuria was significantly elevated in recipients of grafts from BD donors versus LD controls as early as 6 wk postoperatively and increased progressively through the 52-wk follow up. These kidneys also showed consistently more intense and progressive deterioration in renal morphology. Changes in isografts from brain-dead donors were less marked and developed at a slower tempo than in allografts but were always greater than those in controls. The transcription of cytokines was significantly increased in all brain-dead donor grafts. Donor BD accelerates the progression of long-term changes associated with kidney Tx and is an important risk factor for chronic rejection. These results explain in part the clinically noted difference in long-term function between organs from cadaver and living sources.

Animals↗

PubMed2000

Contribution of prolonged ischemia and donor age to chronic renal allograft dysfunction.

As a consequence of an advancing discrepancy between supply of suitable grafts and demand from potential recipients, less than optimal organs are increasingly being used. Although clinical studies demonstrate the involvement of various risk factors, including donor age and duration of ischemia on long-term graft outcome, their individual contribution and correlation has not been followed experimentally. After cold ischemic times of 5, 60, and 120 min, kidney allografts of 3-, 12-, and 18-mo-old Fischer 344 donors were transplanted into 3-mo-old Lewis rats. Age-related changes were examined in matched native uninephrectomized controls. Proteinuria and creatinine clearance were determined, and histologic and immunohistologic studies were assessed and quantified at the end of the observation period (20 wk). All grafts functioned satisfactorily with the exception of one graft each from 12- and 18-mo-old donors with prolonged ischemia (120 min). Functional deterioration and structural changes progressed in parallel to increasing donor age and prolonged ischemia. The impact of expanded ischemia was particularly detrimental in grafts from older donor animals. Donor age and duration of ischemia act in a synergistic manner in our model. Brief ischemic times seem of particular relevance when grafts from older donors are being used.

Aging↗

PubMed1994

[Bioreactor for long-term maintenance of differentiated hepatic cell functions]

A culture model and a bioreactor construction for hepatocyte in vitro culture is described. The reactor is based on capillaries for hepatocyte immobilisation. Four discrete capillary membrane systems, each serving different purposes, are woven to create a three-dimensional framework for decentralized cell perfusion with low metabolite gradients and decentralized oxygenation and CO2 removal. The biochemical performance of reactors initially seeded with 2.5 x 109 pig hepatocytes was evaluated (pig albumin synthesis, midazolam- and lidocaine/MEGX metabolism, galactose elimination, enzymeleakage). The specific construction of the reactor enables a use in pharmacology alternatively to animal experiments.

Journal Article↗

PubMedDate not supplied

Early enteral supply of fiber and Lactobacilli versus conventional nutrition: a controlled trial in patients with major abdominal surgery.

OBJECTIVE: Early enteral nutrition with fiber-containing solutions plus Lactobacillus may reduce bacterial translocation and minimize the incidence of infections after surgery. METHODS: In a prospective, randomized trial in three groups (n = 30/group) of patients after major abdominal surgery, we compared our previous regimen with parenteral nutrition or fiber-free enteral nutrition (group A) with enteral fiber-containing nutrition with living Lactobacillus (group B) and heat-killed Lactobacillus (group C). The main endpoint was the development of bacterial infection. Other analyzed parameters were the durations of antibiotic therapy and hospital stay, non-infectious complications, side effects of the nutrition, and onset of bowel movement. Routine parameters, nutritional parameters, and cellular immune status in the blood were measured preoperatively and on 1, 5, and 10 d postoperatively. RESULTS: The incidence of infections was significantly lower (P = 0.01) in groups B and C with enteral nutrition containing fibers (10% each) than in group A (30%). Patients in group B received antibiotics for a significantly shorter time (P = 0.04) than did the patients in groups A and C. The length of hospital stay and the incidence of non-infectious complications did not differ significantly. Fibers and lactobacilli were well tolerated. There were no general benefits of living Lactobacillus as opposed to heat-killed Lactobacillus in the entire study population, but benefits were observed in the patients with gastric and pancreas resections, although no statistical analysis was done due to their small numbers. CONCLUSIONS: Early enteral nutrition with fiber-containing solutions reduced the rate of postoperative infections in comparison with parenteral nutrition and fiber-free enteral formula. Addition of living Lactobacillus seemed to increase the benefits in patients with gastric and pancreatic resections.

Aged↗

PubMedDate not supplied

Recovery of preservation-injured primary human hepatocytes and nonparenchymal cells to tissuelike structures in large-scale bioreactors for liver support: an initial transmission electron microscopy study.

This study investigated large-scale regeneration and tissue reorganization of adult human liver cells from preservation injured transplant organs. The use of basement membrane protein gels and growth factor enriched culture medium in standard culture flasks promotes liver tissue formation in isolated rat and pig hepatocytes, resulting in prolongation of phenotypic stability and metabolic competence of primary cells in vitro. A special bioreactor construction for high-density three-dimensional cell recovery was developed and isolation of cells from discarded human donor livers was enabled. In vitro regeneration of adult human liver cells isolated from preservation-injured organs took place over a period of 2 weeks in a purpose-built bioreactor. Basement membrane protein and growth factors were avoided. Reorganization of tissue structures was studied using transmission electron microscopy (TEM). This showed regeneration and tissue reorganization of adult human cells from preservation-injured organs by coculture with nonparenchymal cells in the bioreactor. The majority of the aggregated hepatocytes in the bioreactors showed morphological similarities to those in vivo (although not re-formed to hepatocyte plates), exhibiting cell-cell junctions and reconstituted bile canaliculi-like spaces between neighboring hepatocytes. Perfusion channels appeared regularly between cell aggregates. The arrangement of nonparenchymal cells between the hepatocyte aggregates exhibited similarities to liver sinusoids. Endothelial cells often covered the aggregates and formed a borderline to the perfusion channels between the capillaries. Similar to the space of Disse, further nonparenchymal cells were located between the endothelial cells and the parenchymal aggregates. Deposits of biomatrix fibers occurred spontaneously. The regenerated cell mass was close to that of a single liver lobe. In conclusion, the further optimization of bioreactors that enable cell recovery from preservation injury may lead to the utilization of cells from discarded whole or split transplants for extracorporeal temporary liver support therapy or hepatocyte transplantation.

Adult↗

PubMedDate not supplied

Time course of primary liver cell reorganization in three-dimensional high-density bioreactors for extracorporeal liver support: an immunohistochemical and ultrastructural study.

To enable extracorporeal liver support based on the use of primary liver cells, culture models supporting the maintenance of cell integrity and function in vitro are required. In this study the cell organization and ultrastructure of primary porcine hepatocytes cocultured with nonparenchymal cells in three-dimensional high-density bioreactors were analyzed after 10, 20, and 30 days of culture by immunohistochemistry and transmission electron microscopy. Biochemical data showed that metabolic activity of the cells in the system was relatively stable over at least 20 days. Immunohistochemical studies were performed in comparison with donor organ biopsies. They showed that hepatocytes and nonparenchymal cells reaggregated in bioreactors, forming structures partly resembling natural liver parenchyma. Bile duct-like structures characterized by cytokeratin 7 (CK-7) immunoreactivity (IR) were regularly detected. Nonparenchymal cells (vimentin IR) formed sinusoidal-like structures within parenchymal cell aggregates. Proliferative activity (Ki-67 IR) increased over time. The detection of collagen I and laminin indicated the production of extracellular matrix components within bioreactors. The results showed that primary liver cell reorganization and long-term maintenance of their differentiated state were achieved within the bioreactors The findings on cell proliferation indicated that the culture model is also of interest for further in vitro studies on cell regeneration and tissue formation.

Adaptation, Physiological↗