Establishment of an inbred strain of LEC (Long Evans Cinnamon) rats with spontaneous hepatitis

At the Center for Experimental Plants and Animals, Hokkaido University, two inbred strains, Long Evans Cinnamon (LEC) and Long Evans Agouti (LEA), which were selected for coat colour, were isolated from a closed colony of Long Evans rats. While the two inbred strains were maintained by sibmating, only LEC rats, over 24-generation, spontaneously developed acute hepatitis with sudden appearance of systemic jaundice at around four months after birth. The frequency of acute hepatitis was 80 to 90% and the disease in nearly 80% of these rats were progressive and they died within two weeks after onset, with their clinical course and histopathological findings similar to those of human fulminant hepatitis. LEC rats with spontaneous hepatitis had strong-conversion of urine-bilirubin, ultimate increase of blood-bilirubin and abnormal increase of serum-transaminases (GOT, GPT; GOT greater than GPT). Histopathological findings of the livers in the rats with acute hepatitis showed spotty necrosis and abnormal hepatocytes containing giant bizarre nuclei and in the rats with fulminant-type hepatitis showed central or coagulated necrosis and marked infiltration of inflammatory cells. Serum levels of albumin in LEC rats before being affected by hepatitis were low compared with those of LEA rats and especially characteristic fact was that cellulose-acetate electrophoresis could not reveal gamma-globulin fraction in LEC rats of 6-week and 12-week old, which will be a clue to analyze the etiology of hepatitis in LEC rats.     

The role of oval cells in rat hepatocyte transplantation

BACKGROUND: Oval cells are liver cells capable of differentiating into either hepatocytes or biliary epithelial cells. We compared growth of hepatocytes and biliary epithelial cells between spleens transplanted with oval cell-free and oval cell-enriched rat liver cells. METHODS: Oval cell-enriched liver cells were obtained from livers of adult rats that had undergone treatment with acetylaminofluorene and partial hepatectomy, although oval cell-free liver cells were obtained from livers of untreated rats. Hepatocyte and biliary epithelial cell growth in the spleen was evaluated by counting periodic acid-Schiff-positive cells and cytokeratin 19-positive cells respectively in sections from transplanted spleens. RESULTS: Spleens transplanted with oval cell-free liver cells and spleens transplanted with oval cell-enriched liver cells contained similar numbers of hepatocytes after 2 weeks. Numbers of hepatocytes in spleens transplanted with oval cell-free liver cells decreased markedly at 4 and 8 weeks, then increasing slightly until 32 weeks. In spleens transplanted with oval cell-enriched liver cells, numbers of hepatocytes decreased only slightly at 4 weeks and then increased markedly. At 4, 8, 12, 16, 24, and 32 weeks, numbers of hepatocytes in spleens transplanted with oval cell-enriched liver cells respectively were 2.3, 3.5, 4.5, 6.7, 6.3, and 15.1 times hepatocyte numbers in spleens transplanted with oval cell-free liver cells. Numbers of biliary epithelial cells in spleens receiving oval cell-enriched liver cells showed changes similar to those in spleens transplanted with oval cell-free liver cells, increasing markedly at 4 weeks and then markedly and rapidly decreasing. CONCLUSIONS: Intrasplenic transplantation of oval cell-enriched liver cells enhanced growth of hepatocytes compared with transplantation of oval cell-free liver cells; this was not true for biliary epithelial cells.     

HVEGF165 increases survival of transplanted hepatocytes within portal radicles: suggested mechanism for early cell engraftment

VEGF is a potent angiogenic factor that promotes hepatocyte growth, increases permeability of blood vessels, and induces vasodilatation, and may accelerate engraftment and function of transplanted hepatocytes. The aim was to study the effect of VEGF on early hepatocyte engraftment. Thirty-two Lewis syngeneic female rats underwent 70% partial hepatectomy. Eighteen received 240 ng VEGF165 and 14 received saline for control. Thereafter, intrasplenic transplantation of 10(7) male hepatocytes was done. Semiquantitative analysis of PCR product of the SRY region of the Y-chromosome was performed. Paraffin-embedded sections were stained for H&E and for PCNA immunostaining. By PCR, male hepatocytes were identified in 8 livers out of 14 VEGF-treated rats at 24-48 h, compared with only 1 liver out of 8 controls. Transplanted cells were seen within portal vessels radicles in 7 out of 14 VEGF-treated rats for as long as 48 h posttransplantation, compared with only one control liver at 24 h. There was no histological sign of cell injury to transplanted or adjacent cells. Two weeks after transplantation male transplanted cells were identified in two out of four rats treated with hVEGF165 and in one out of six rats treated with saline. No transplanted cells were detected within portal tracts 14 days after transplantation. hVEGF165 enhances the presence of transplanted hepatocytes within portal vessels after transplantation. We suggest an additional mechanism for cell engraftment, whereby transplanted hepatocytes first stick to each other in the portal radicles. Later they become included in the liver parenchyma as groups of organized cells in a process stimulated by VEGF.     

Fulminant Wilson's Disease Requiring Liver Transplantation in One Monozygotic Twin Despite Identical Genetic Mutation

Acute decompensated Wilson's disease (WD) that presents as fulminant hepatic failure carries significant mortality without hepatic replacement. The abnormal gene implicated in WD, ATP7B, has been mapped to chromosome 13, and leads to decreased passage of copper from hepatocytes to bile. Excess copper accumulation exceeds hepatocyte storage capacity resulting in intracellular necrosis, apoptosis and cell death in various organs of the body. The hepatic injury induced by the abnormal accumulation of copper in WD has variable presentation such as acute hepatitis, rapid hepatic deterioration resembling fulminant hepatic failure, or as progressive chronic liver disease in the form of chronic active hepatitis or cirrhosis. There are reports in the literature describing monozygotic (identical) twins with similar hepatic progression requiring liver transplantation, however, with different neurological outcome after transplant. We report a case of one monozygotic twin presenting with acute liver failure requiring emergent liver transplantation while the other twin presented with mild liver disease, when both shared an identical genetic mutation.     

Hepatocyte transplantation for total liver repopulation

Hepatocyte transplantation (HT) is an attractive therapeutic alternative to liver transplantation. A number of experiments have shown the feasibility of total liver parenchymal cell replacement by transplanted hepatocytes. In this review, we would like to highlight researches and clinical reports of HT for liver repopulation. Cellular source of clinical HT should be safety. Immortalized cells, hepatic stem cells, and other stem cells have been used for an experimental model for HT. The exact mechanism of the cell engraftment after HT has not been completely understood, although there were some markers to detect and investigate transplanted cells. In order to achieve liver repopulation following HT, a mild hepatic damage may need to facilitate cell engraftment and replace the host liver by transplanted cells. Hormonal factor may use for the same purpose. Despite the results of preclinical studies promising clinical benefits for cell therapy, the clinical experience of HT has been disappointing, except in a few cases. HT may become an alternative for liver transplantation in the future; however, many efforts should made before establishing an effective method for HT and liver replacement therapy.     

Characterization of long-term survival of syngeneic hepatocytes in rat peritoneum

Hepatocyte transplantation is a potential therapy for both acute and chronic hepatic insufficiency and also for treatment of inborn errors of metabolism affecting the liver. The peritoneum is one site for implantation and has several advantages: cells implanted there can be easily identified and observed, and it has a relatively large capacity. Long-term survival using "pure" hepatocytes in the peritoneum have been disappointing. We hypothesized that cotransplantation of hepatocytes with nonparenchymal cells would help maintain differentiated hepatocyte function. Rat liver cells transplanted intraperitoneally into August rats were sacrificed at 7 days, 1, 3, 6, 9, and 12 months and analyzed for presence, basal proliferation, and functionality of hepatocytes. To demonstrate that ectopic hepatocytes remained susceptible to exogenous growth factors affecting cell proliferation, rats 9 and 12 months after transplantation were stimulated with tri-iodothyronine and KGF. Hepatocytes were identified 7 days to >12 months, by H&E and immunohistochemically, as ectopic islands in the omental fat. Functionality was confirmed by glycogen deposition. Basal proliferation in 7-day rats was 28.0 +/- 10/1000 hepatocytes in ectopic islands (cf. 5.70 +/- 2.7/1000 in recipient liver). Proliferation in ectopic islands was greater than host liver. Growth factor-stimulated proliferation in ectopic islands induced a 70-fold increase in DNA synthesis. In conclusion, hepatocytes transplanted with nonparenchymal cells survive, proliferate, and function in the peritoneum of normal rats, and respond to exogenous growth stimuli. Their survival and proliferation in the presence of a normal functioning liver has implications for the potential use of the peritoneal site clinically for supplementation of liver function in metabolic disorders.     

Transdifferentiation of bioencapsulated bone marrow cells into hepatocyte-like cells in the 90% hepatectomized rat model.

Under specific conditions, bone marrow cells can transdifferentiate into a variety of cell types including hepatocytes. In this study, bioencapsulated bone marrow cells were transplanted intraperitoneally into 90% hepatectomized rats. We then followed the transdifferentiation of the bone marrow cells and the effect of this on liver regeneration in this liver failure model. Bone marrow cells isolated from Wistar rats were bioencapsulated using alginate-polylysine-alginate method. These bioencapsulated bone marrow cells were transplanted intraperitoneally into 90% hepatectomized Wistar rats. Blood chemistry, HGF, liver weight, and survival of the recipient rats were evaluated. Histology and immunocytochemistry were used to analyze the bioencapsulated cells before and 14 days after transplantation. Unlike free bone marrow cells, transplantation of bioencapsulated bone marrow cells improved the survival of 90% hepatectomized rats and improved the blood chemistry with an efficacy similar to that of bioencapsulated hepatocytes or free hepatocytes transplantation. Some bioencapsulated bone marrow cells expressed hepatocytes markers of cytokeratins 8, cytokeratins 18, albumin, and AFP after 2 weeks of transplantation. These results suggest that syngeneic bioencapsulated bone marrow cells can transdifferentiate into hepatocyte-like cells in the peritoneal cavity of 90% hepatectomized rats and increased the survival rates of these rats. In conclusion, these findings suggest the potential for a new alternative to hepatocyte transplantation for cellular therapy of acute liver failure.     

骨髓细胞移植改善宿主肝细胞功能研究

目的 观察骨髓问充质细胞(BMCs)移植能否提高严重肝功能损害合并再生障碍的同种先天性无白蛋白大鼠(F344alb)肝再生和修复能力.方法 F344大鼠为供体,F344alb受体鼠接受Retrorsine(RS)1次/2周腹腔注射2次后4周行2/3肝切除(PH).正常F344alb为组Ⅰ(n=5);BMCs移植为组Ⅱ(n=8);RS/PH预处理为组Ⅲ(n=8);RS/PH预处理后BMCs移植为组Ⅳ(n=8);RS/PH预处理后肝实质细胞移植为组V(n=8).4周后行各组大鼠肝脏形态学和组化染色研究,检测肝功能,及肝组织和骨髓基因检测.结果 (1)生存率:组Ⅳ75%,组Ⅴ 50%,组Ⅲ37.5%,组Ⅰ和组Ⅱ 100%.(2)4周后组肝再生率(67.38±8.66)%显著高于组Ⅳ、Ⅲ[(55.31±8.69)%,(44.27±6.51)%].(3)PH后1 d,组Ⅲ、Ⅳ、V血清TB、ALT显著升高;PH后2 d,组Ⅳ血清,rB、ALT显著下降.(4)组Ⅳ、Ⅴ肝组织切片白蛋白免疫组织化学染色显示白蛋白染色阳性肝细胞呈簇状分布.(5)F344来源白蛋白基因片段出现在组Ⅳ、Ⅴ大鼠肝组织内.(6)PH后2、4周,组Ⅳ、Ⅴ血清白蛋白显著升高.结论 BMCs移植可提高严重肝损合并再生障碍受体鼠肝再生能力,保护肝功能,促进肝修复.     

Combined immunodeficiency in LEC (Long Evans Cinnamon) rats with spontaneous hepatitis

We investigated LEC rats immunopathologically which spontaneously developed hepatitis to find out the genesis, in comparison with non-hepatitis LEA (Long Evans Agouti) rats. 1) Wet weights of the spleen and thymus of 6-week old LEC rats were significantly lighter than those of LEA rats of the same age. 2) Serum IgG (Immunoglobulin G) in LEC rats remained markedly low after the age of two months and IgG antibody formation to SRBC (Sheep Red Blood Cell) as detected by plaque assay was also significantly suppressed. On the other hand, IgM antibody formation to SRBC was significantly suppressed through serum IgM level in LEC rats was normal or rather increased. 3) Blastogenic responses of spleen cells to PHA and Con A were much more suppressed in LEC rats than in LEA rats. 4) Cytostatic activity of intraperitoneal macrophages against tumor cells was more evident in LEC rats than in LEA rats, but there was no difference in NK (natural killer) activity between the two rat strains. From these results, it is speculated that spontaneously hepatitis-developing LEC rats possess T and B cell deficiency (combined immunodeficiency) and that the increase of macrophage and NK cell activities are linked to the genesis of developing hepatitis.     

Selective repopulation of mice liver after Fas-resistant hepatocyte transplantation

Hepatocyte transplantation has been proposed as a potential therapeutic method to treat irreversible liver failure and inherited hepatic disorders, although transplanted cells do not easily reconstruct the liver tissue under intact conditions. This study was aimed at modulating the recipient liver conditions to promote repopulation of the liver after hepatocyte transplantation. Hepatocytes isolated from male MRL-lpr/lpr (lpr) mice with a mutation of Fas antigen were transplanted in a number of 1 x 10(6) cells in female MRL-+/+ (wild-type mice) by intrasplenic injection. An agonistic anti-Fas antibody (0.15 mg/kg) was administered intravenously 24 h after cell transplantation. We also administrated the antibody at 0.3 mg/kg 1 week after grafting and at 0.6 mg/kg 2 weeks after transplantation. The liver specimens were taken at different time intervals for histological examination. The reconstructed male lpr hepatocytes in the female wild-type mice were determined by a real-time quantitative PCR assay using the primers and probe for the sry gene. The pathologic findings of the recipient livers after treatment with anti-Fas antibody revealed a large number of apoptotic hepatocytes. The grafted lpr hepatocytes were observed to reconstruct as much as 6.9% of the recipient liver in the anti-Fas antibody-treated group 3 months after transplantation. In contrast, we observed the transplanted cells at lower than 0.1% in the nontreated livers. These findings demonstrated that repeated induction of apoptosis in recipient hepatocytes shifts the environment of the liver to a regenerative condition. This method may be useful to promote the reconstruction of transplanted hepatocytes in a recipient liver.     

The cytokinetic behavior of donor hepatocytes after syngenic hepatocyte transplantation into the spleen

The cytokinetic behavior of isolated hepatocytes transplanted into the spleen of syngenic normal Wistar rats was studied. Hepatocyte transplantation (HTX) was performed by the intrasplenic injection of 10(7) isolated hepatocytes. The proliferation index (PI) of intrasplenic donor hepatocytes was assessed by immunocytochemical visualization of DNA-synthesizing cells after pulse-labeling with bromodeoxyuridine (BrdU), a thymidine analogue. A method for determination of intrasplenic liver mass based on tissue glutamate dehydrogenase content was developed. The spontaneous PI of donor hepatocytes at 12 and at 20 weeks post-HTX amounted to around 3%. A significant increase of intrasplenic liver mass was demonstrated between the 12th and 20th week post-HTX (from 8.1 +/- 0.8% to 10.8 +/- 0.8% of spleen weight, P less than 0.05). After partial hepatectomy (PH) at 12 weeks post-HTX, the PI of liver cells in the spleen showed a transient increase up to about 10%, which rapidly declined to the "spontaneous" level of 3%. However, PH did not cause an additional increase in intrasplenic liver mass. This study shows that continuous mitotic activity of intrasplenic hepatocytes results in an actual increase of liver mass in spleen. Although a short-lived increase of proliferative activity of ectopically grafted hepatocytes was shown to occur after PH in the HTX-treated rat, this procedure did not result in an additional increase of intrasplenic liver tissue.     

New method of hepatocyte transplantation and extracorporeal liver support

A technique has been developed by the authors that allows hepatocyte attachment on collagen-coated microcarriers resulting in prolonged hepatocyte viability and function both in vivo and in vitro. Rat hepatocytes were obtained by portal vein collagenase perfusion. Intraperitoneally transplanted microcarrier-attached normal hepatocytes into congeneic Gunn rats were functioning 3-4 weeks later, as shown by the presence and persistence of conjugated bilirubin in recipient bile, sustained decrease in serum bilirubin, uptake of Tc99m-DESIDA, and morphologic criteria. Intraperitoneal transplantation of normal microcarrier-attached hepatocytes into genetically albumin deficient rats (NAR) resulted in marked increase in plasma albumin levels (6 days without and 21 days with Cyclosporin A immunosuppression). Microcarrier-attached hepatocytes transplanted after 2 weeks of storage at -80 C into congeneic Gunn rats were viable and functional as assessed by criteria outlined above. An extracorporeal liver perfusion system was developed using the microcarrier-attached hepatocytes that was capable of synthesizing and conjugating bilirubin and synthesizing liver-specific proteins.     

Improvement of the effects of intrasplenic transplantation of hepatocytes after 90% hepatectomy in the rat by cotransplantation with pancreatic islets

Acute liver failure is associated with high mortality. Whether support with transplanted hepatocytes improves the outcome is not established. We studied the potential beneficial effects of intrasplenic transplantation of hepatocytes in conjunction with islets of Langerhans on 90% hepatectomy-induced acute liver failure in rats. We found that all control rats died within 48 hr following 90% hepatectomy. In contrast, the mortality decreased significantly in rats transplanted with 10(7) hepatocytes into the spleen parenchyma at 1-3 days prior to 90% subtotal hepatectomy, whereas no significant reduction in mortality was seen in rats transplanted with hepatocytes immediately after the operation. However, cotransplantation of hepatocytes and 400 isolated pancreatic islets into the spleen reduced mortality when performed immediately after the 90% hepatectomy. Therefore, hepatocyte transplantation reduces mortality after 90% hepatectomy only if performed prior to the hepatectomy. However, transplantation of hepatocytes in conjunction with pancreatic islets reduces mortality when performed at the same time as 90% hepatectomy. Hence, the combined transplantation of hepatocytes and islets might offer support after liver failure.     

Liver repopulation and long-term function of rat small hepatocyte transplantation as an alternative cell source for hepatocyte transplantation.

Hepatocyte transplantation (HT) is an attractive therapeutic modality for liver disease as an alternative for liver organ transplantation. Primary fresh hepatocytes (FHs) are the exclusive cell source that has been used for clinical HT. However, the use of FHs is limited due to a shortage of donor cells. Small hepatocytes (SHs) are hepatic progenitor cells and can be isolated not only from rodents but also from humans. SHs can proliferate in vitro and express liver functions, although conventional hepatocytes lose them within a short period after culture. SH functions in vivo have never been studied. We therefore investigated HT using SHs to evaluate cell engraftment and function compared to HT using FHs. The donor cell number in the SH group was smaller than that in the FH group at HT. The cell engraftment in the SH group was smaller in the liver and larger in the spleen than in the FH group. The cell engraftment in the liver increased after HT; however, that in the spleen decreased after HT in both groups. HT using SHs supported the serum albumin level in the NAR experiment as well as that using FH, and albumin mRNA was detectable in the recipients' tissues at 12 weeks after HT. In conclusion, HT using SHs showed hepatic repopulation similar to that using FHs. This suggests that both SHs and FHs can repopulate the liver as if they were hepatic stem cells. In addition, HT using SHs supported liver functions such as albumin correction at the same level as that using FHs. These observations strongly support the idea that SHs could be an alternative to primary FHs as a novel cell source for future HT.     

Liver repopulation by transplanted hepatocytes and risk of hepatocellular carcinoma

BACKGROUND: Transplantation of isolated hepatocytes in rats treated with retrorsine (RS) results in massive repopulation of the host liver. In this study, the long-term fate of hepatocytes transplanted into RS-treated recipients was followed for up to two years. METHODS: Dipeptidyl-peptidase type IV-deficient (DPPIV) Fischer 344 rats were given two injections of RS (30 mg/kg), followed by transplantation of 2 million hepatocytes, isolated from a syngenic, DPPIV donor. RESULTS: Extensive (91+/-7%) liver replacement by transplanted hepatocytes was observed in animals sacrificed 18 months posttransplantation. Similar levels of repopulation persisted at two years (87+/-5%). No evidence of preneoplastic and/or neoplastic evolution of the transplanted cell population was present in the RS-treated and repopulated livers at any time point considered. Furthermore, serum parameters related to hepatocyte function and integrity were in the normal range. In control groups given cell transplantation in the absence of prior treatment with RS, only small clusters of donor-derived, DPPIV hepatocytes were discerned. CONCLUSIONS: These results indicate that liver repopulation in this model is largely stable, persisting for up to two years and allowing for a normal liver function. In addition, no increased risk of neoplastic transformation appears to be associated with the process of liver repopulation for as long as over two thirds of the life span of the recipient animal.     

Construction of liver tissue in vivo with preparative partial hepatic irradiation and growth stimulus: investigations of less invasive techniques and progenitor cells

Background

The selective proliferation of transplanted hepatocytes with a growth stimulus, such as partial hepatectomy or hepatocyte growth factor, concomitant with hepatic irradiation (HIR), which can suppress proliferation of host hepatocytes, has been reported. We have conducted experiments that focused on less invasive and clinically applicable techniques and progenitor cells.

Materials and methods

First, dipeptidyl-peptidase IV-F344 or jaundiced Gunn rats underwent partial HIR (only 30% of whole liver) and portal vein branch ligation (PVBL) of one lobe, followed by intrasplenic hepatocyte transplantation at 1 × 10⁷. Second, after partial HIR and PVBL, two types of progenitor cells were transplanted (i.e., small hepatocytes (SHs) or adipose-derived mesenchymal stem cells.

Results

Sixteen weeks after transplantation, the donor cells constituted > 70% of the hepatocytes of the irradiated lobe, showing connexin 32, phosphoenolpyruvate carboxykinase-1, and glycogen storage. Moreover, the serum bilirubin level had decreased significantly in the jaundiced Gunn rats and remained at this level throughout the 24 wk experimental period. The SHs grew more quickly than the hepatocytes. After 8 wk, around 40% of the host hepatocytes had been replaced by transplanted SHs. Although the donor adipose-derived mesenchymal cells were engrafted after 8 wk, their proliferation was not observed.

Conclusions

HIR, combined with PVBL, can be given to a selective liver lobe and is a less-invasive but effective method for proliferation of transplanted hepatocytes. Even a smaller number of SHs can construct liver tissue with their prevailing proliferative ability.     

Intrasplenic hepatocyte transplantation prolonged the survival in Nagase analbuminemic rats with liver failure induced by common bile duct ligation

It has already been established that hepatocyte transplantation (HTx) in animal models, such as both chemically and surgically induced acute liver failure, liver-based metabolic disease, and cirrhosis, resulted in significant improvement of liver function and survival. However, the efficacy of hepatocyte transplantation in secondary cholestatic liver disease is not well known. In this study, we transplanted hepatocytes into the spleen of Nagase analbuminemic rats (NARs) with common bile duct ligation (CBDL) to evaluate the function of transplanted hepatocytes by both of serum albumin levels and total bilirubin levels. CBDL was carried out on NARs to induce liver failure. Lewis rat hepatocytes were transplanted in NARs 7 days after CBDL. Animals, in groups of four, underwent the following interventions: group 1--intrasplenic transplantation of 30 x 106 primary Lewis rat hepatocytes in NARs with CBDL (n=4), group 2--intrasplenic injection of 0.5 ml DMEM in NARs with CBDL (n=4); group 3--CBDL only (n=4); group 4--intrasplenic transplantation of 30 x 106 primary Lewis rat hepatocytes in NARs (n=4). Both bilirubin levels and albumin levels in NARs with CBDL were significantly improved post-HTx. Animals receiving hepatocyte transplantation survived longer than animals in nontransplant control groups. This study indicates that hepatocytes can be transplanted to temporarily provide life-supporting liver-specific metabolic function and prolong the survival in recipient rats with liver failure induced by CBDL.     

Can hepatocytes proliferate when transplanted into the spleen? Demonstration by autohistoradiography in the rat

The aim of this work was to study hepatocyte multiplication after transplantation into the spleen, in order to apply this technique to the treatment of chronic liver disease. Hepatocytes isolated by an in situ collagenase perfusion technique in Wistar Furth rats were injected into the splenic parenchyma of three groups of syngeneic rats: controls with normal liver (group 1), 75% hepatectomies (group 2), and end-to-side portacaval shunts (group 3). The proliferation of transplanted hepatocytes was studied by autohistoradiography after the intraperitoneal administration of 0.6 microCi/g body weight of [3H]-thymidine, at 1, 3, 7 and 15 days after transplantation of hepatocytes. Significant incorporation of [3H]-thymidine by the transplanted hepatocytes during the study period was observed mostly in groups 2 and 3. The incorporation, although delayed was sustained and of greatest magnitude in the portacaval-shunted animals. The ability of transplanted hepatocytes to proliferate in the spleen, particularly after a portacaval shunt, indicates that this procedure may have therapeutic applications in the treatment of chronic liver disease.     

Albumin-Producing Hepatocytes Derived from Cryopreserved F344 Rat Bone Marrow Cells Transplanted in the Livers of Congenic Nagase's Analbuminemic Rats

Purpose Hematopoietic stem cells (SCs) are thought to have the potential to differentiate into hepatocytes; however, this potential has not been reported for cryopreserved SCs. We investigated whether cryopreserved bone marrow cells (BMCs) from F344 rats (F344) can induce the growth of albumin-producing hepatocytes in the livers of congenic Nagase's analbuminemic rats (F344alb). Methods F344 BMCs were cryopreserved in University of Wisconsin (UW) solution containing 10% fetal bovine serum and 12% dimethylsulfoxide, at −80°C. After thawing, 20 × 10⁶ cells were infused via the portal vein into the livers of F344alb immediately after 70% hepatectomy (PH). We examined the recipient livers for albumin-positive (alb+) hepatocytes and albumin mRNA, and measured the serum albumin levels 4 weeks later. Results Single and double alb+ hepatocytes were occasionally seen in the F344alb livers without the BMC transplantation. However, clusters consisting of more than three alb+ hepatocytes were seen in the livers of recipients transplanted with the cryopreserved BMCs after PH, the same as in the livers transplanted with freshly isolated BMCs. Normal albumin mRNA was detected in the recipient livers and the serum albumin levels were increased. Conclusion Cryopreserved F344 BMCs can induce the growth of alb+ hepatocytes after transplantion in the F344alb liver after PH.