Rapid clearance of transplanted hepatocytes from pulmonary capillaries in rats indicates a wide safety margin of liver repopulation and the potential of using surrogate albumin particles for safety analysis

BACKGROUND/AIMS: Applications of liver repopulation by hepatocyte transplantation require analysis of cell biodistributions, particularly when portasystemic shunting coexists. The aims of this study were to determine the fate of hepatocytes transplanted into the pulmonary vascular bed and to examine whether cell biodistributions could be approximated by convenient surrogates. METHODS: Rat hepatocytes and macroaggregated serum albumin particles of similar sizes were injected into the portal and pulmonary vascular beds of rats, followed by biodistribution, survival and function analyses. RESULTS: Although functionally intact, virtually all hepatocytes were cleared from the pulmonary capillaries within 24 h. Serum albumin levels increased minimally in Nagase analbuminemic rats with or without portacaval shunting to enhance delivery of portal factors to transplanted cells in lungs. Despite intravenous injection of hepatocytes approaching >1x10(9) cells in humans, the hemodynamic changes were limited to transient increases in right atrial pressures. The hepatocyte distributions in specific vascular beds were largely reproduced by macroaggregated human serum albumin particles. CONCLUSIONS: Incidental intrapulmonary cell translocations during liver repopulation will have a wide safety margin. Use of macroaggregated serum albumin particles as surrogates for initial short-term biodistribution and safety analysis will advance hepatocyte transplantation, as the cost of GLP-certified laboratories and consumption of scarce donor livers will be avoided.     

Animal model for liver cell banking from non-heart beating donors after prolonged ischaemia time

BACKGROUND AND AIM: Although there is a growing interest on the use of non-heart beating donors to enlarge the liver donor pool, livers with prolonged warm ischaemia time are not currently considered for organ transplantation. We hypothesised that these organs may represent a source of hepatocytes for cell transplantation and/or use in bioartificial liver devices. Thus, we investigated if prolonged ischaemia could influence the recovery and viability of functional hepatocytes dissociated from rat livers. METHODS: Hepatocytes were isolated from the liver within 15 min after death (t=15 min) and after 4, 8 and 12h of ischaemia. Cells were either maintained in culture or cryopreserved. In all products, we evaluated cell recovery and viability, hepatocyte markers and cellular functions, including albumin and urea production. RESULTS: The number of cells per gram of tissue was similar at 15 min, 4 and 8h, while it was significantly decreased at 12h. About 0.2 x 10(6) viable cells expressing hepatocyte markers and producing albumin and urea were isolated up to 8h of ischaemia per gram of tissue. CONCLUSIONS: Recovery of viable and functional hepatocytes seems possible after prolonged ischaemia time. These data warrant the evaluation of hepatocyte isolation from human livers of non-heart beating donors.     

Proliferation of L02 human hepatocytes in tolerized genetically immunocompetent rats

AIM： To investigate whether human hepatocytes could proliferate after transplantation to normal immunocompetent rats treated with 2-acetaminofluorene or Retrorsine and partial hepatectomy. METHODS： L02 hepatocyte-tolerant Sprague-Dawley rats were injected with Retrorsine, 2-acetaminofluorene or normal saline. L02 hepatocytes were then transplanted via the spleen. Human albumin and its mRNA, specific proliferating cell nuclear antigen （PCNA）, L02 hepatocyte dynamic distribution, number density and area density of PCNA-positive cells in the liver were determined. RESULTS： All the examined indicators were not significantly different between the rats treated with 2-acetaminofluorene and normal saline, which was not the case with rats treated with Retrorsine. A dynamic distribution of L02 hepatocytes in the rat liver was detected from wk 1 to mo 6 after transplantation in the Retrorsine group and from wk 1 to 10 in the 2-acetaminofluorene group. Human albumin and its mRNA were detected from wk 2 to mo 6 in the Retrorsine group and from wk 1 to 8 in the 2-acetaminofluorene group. Specific human PCNA was detected in the rat liver from wk 2 to mo 6 in the Retrorsine group and from wk 2 to 6 in the 2-acetaminofluorene group. Human albumin and its mRNA contents as well as the number of PCNA positive cells reached a peak at wk 4. CONCLUSION： L02 human hepatocytes could not proliferate significiantly after transplantation to the normal, immunocompetent rats treated with 2-acetaminofluorene.L02 human hepatocytes can survive for 10 wk after transplantation and express human albumin for 8 wk. L02 human hepatocytes can proliferate and express human albumin for 6 mo after transplantation to the rats treated with Retrorsine. The chimeric L02 human hepatocytes, which then underwent transplantation into tolerant rats, were normal in morphogenesis, biochemistry and function.     

Treatment of cirrhosis and liver failure in rats by hepatocyte xenotransplantation

BACKGROUND & AIMS: Hepatocyte transplantation has been proposed as an alternative to liver transplantation for the treatment of hepatic failure. A major limitation to this form of therapy is the availability of human livers as a source of hepatocytes. The use of porcine hepatocytes might address this problem; however, xenogeneic hepatocytes are thought to be functionally incompatible across species and susceptible to irreversible rejection. METHODS: Liver cirrhosis was induced with phenobarbital and carbon tetrachloride. Only rats with decompensated liver failure that did not correct 4 weeks after the discontinuation of carbon tetrachloride were subjected to intrasplenic rat or porcine hepatocyte transplantation. The immunologic integrity of cirrhotic rats was assessed by allogeneic skin grafting, and the immune response to transplanted porcine hepatocytes was assessed by enzyme-linked immunosorbent assay. RESULTS: Porcine hepatocytes restored metabolic function and prolonged the survival of cirrhotic rats, as well as rat hepatocytes. Cirrhotic rats retained the ability to reject allogeneic skin grafts and showed an immune response to the engrafted hepatocytes. Despite this, survival of transplanted porcine hepatocytes was accepted in cirrhotic rats for a period of weeks without immunosuppression. Conventional immunosuppression with FK506 allowed successful retransplantation with hepatocytes from a second porcine donor. CONCLUSIONS: Hepatocytes transplanted between widely divergent species can function to correct liver failure in cirrhotic rats and prolong their survival. Conventional immunosuppression allows long-term functioning of xenogeneic hepatocyte retransplants and suggests that hepatocyte xenotransplantation might be useful as a bridge to liver transplantation and could potentially provide long-term hepatic support.     

Hepatocyte transplantation in rats with decompensated cirrhosis

Hepatocyte transplantation improves the survival of laboratory animals with experimentally induced acute liver failure and the physiological abnormalities associated with liver-based metabolic deficiencies. The role of hepatocyte transplantation in treating decompensated liver cirrhosis, however, has not been studied in depth. To address this issue, cirrhosis was induced using phenobarbital and carbon tetrachloride (CCL(4)) and animals were studied only when evidence of liver failure did not improve when CCL(4) was held for 4 weeks. Animals received intrasplenic transplantation of syngeneic rat hepatocytes (G1); intraperitoneal transplantation of syngeneic rat hepatocytes (G2); intraperitoneal transplantation of a cellular homogenate of syngeneic rat hepatocytes (G3); intraperitoneal transplantation of syngeneic rat bone marrow cells (G4); or intrasplenic injection of Dulbecco's modified Eagle medium (DMEM) (G5). After transplantation, body weight and serum albumin levels deteriorated over time in all control (G2-G5) animals but did not deteriorate in animals receiving intrasplenic hepatocyte transplantation (G1) (P <.01). Prothrombin time (PT), total bilirubin, serum ammonia, and hepatic encephalopathy score were also significantly improved toward normal in animals receiving intrasplenic hepatocyte transplantation (P <. 01). More importantly, survival was prolonged after a single infusion of hepatocytes and a second infusion prolonged survival from 15 to 128 days (P <.01). Thus, hepatocyte transplantation can improve liver function and prolong the survival of rats with irreversible, decompensated cirrhosis and may be useful in the treatment of cirrhosis in humans.     

Colonization of albumin-producing hepatocytes derived from transplanted F344 rat bone marrow cells in the liver of congenic Nagase's analbuminemic rats

BACKGROUND/AIMS: We investigated whether bone marrow cells (BMCs) of normal rats can be transformed in albumin-producing hepatocytes in analbuminemic rat livers. METHODS: BMCs (2 x 10(7)) from F344 rats (F344) were infused via the portal vein into the livers of congenic Nagase's analbuminemic rats (F344alb) immediately after 70% hepatectomy (PH). Alternatively, F344alb were hematopoietically reconstituted with F344 BMCs by whole body irradiation and BMC transplantation before PH. The recipients were examined for albumin positive (alb +) hepatocytes and albumin mRNA in the livers as well as serum albumin levels 4 weeks later. Sry3 in situ hybridization was done for the livers of female F344alb that received male F344 BMCs. RESULTS: Livers of untreated F344alb contained a few single and double alb+hepatocytes, but these did not form clusters after PH. Clusters (>3 alb + hepatocytes) were detected in livers of the recipients which were transplanted with BMCs immediately after PH as well as the reconstituted F344alb with or without PH. Normal albumin mRNA was detected in the recipient livers, and serum albumin levels were increased. Sry3 was identified in the alb+clusters in the female recipients. CONCLUSIONS: Transplanted BMCs from normal rats can increase clusters of albumin-producing hepatocytes within the liver of analbuminemic rats.     

Treatment of liver failure in rats with end-stage cirrhosis by transplantation of immortalized hepatocytes

The shortage of organ donors has impeded the development of human hepatocyte transplantation. Immortalized hepatocytes could provide an unlimited supply of transplantable cells. To determine whether immortalized hepatocytes could provide global metabolic support in end-stage liver disease, 35 immortalized rat hepatocyte clones were developed by transduction with the gene encoding the simian virus 40 T antigen (SV40Tag). The SV40Tag sequence and a suicide gene, herpes simplex virus thymidine kinase (HSV-tk), were flanked by loxP sequences so that they could be excised by Cre/lox recombination. When transplanted into the spleens of portacaval-shunted rats, 3 of the 35 immortalized hepatocyte clones prevented the development of hyperammonemia-induced hepatic encephalopathy. The protection was reversed by treatment with ganciclovir, which kills HSV-tk-expressing cells. Transplantation of alginate-encapsulated, immortalized hepatocytes into the spleens of cirrhotic rats resulted in significant improvement in prothrombin time, serum albumin and bilirubin levels, hepatic encephalopathy score, and duration of survival. The metabolic support provided by the immortalized cells equaled that observed after transplantation of primary rat hepatocytes. In conclusion, immortalized hepatocytes can function as well as primary hepatocytes following transplantation and can be engineered to contain safeguards that could make them clinically useful. Further investigation is warranted regarding the mechanisms of loss of mass or function of the transplanted hepatocytes over time and how the relatively few engrafted hepatocytes can ameliorate liver decompensation in cirrhosis.     

L02细胞人鼠嵌合肝模型的建立

目的 研究正常人L02肝细胞移植到具有正常免疫活性的大鼠肝内的存活情况，建立稳定的人鼠嵌合肝动物模型。方法 SD大鼠出生前宫内腹腔注射L02肝细胞，诱导胎鼠对人L02肝细胞产生免疫耐受，出生2周后经脾移植DiI染色后的人L02肝细胞，建立人鼠嵌合肝动物模型。采用免疫荧光、免疫组织化学、DiI荧光示踪等方法，在不同时相分别检测人白蛋白和特异性人增殖细胞核抗原，在荧光显微镜下观察人L02肝细胞在鼠肝内的分布。结果 于移植后1、2、4、6、8、10周在荧光显微镜下观察到人L02肝细胞在鼠肝内的动态分布，移植后2、4、6、8周大鼠均检测出人白蛋白，移植后2、4、6周检测出特异性人增殖细胞核抗原。结论 移植的人L02肝细胞在具有正常免疫活性的免疫耐受鼠体内能够存活、增殖，并产生人白蛋白。     

L02细胞在2-乙酰氨基芴处理大鼠肝中的增殖

目的:应用2-乙酰氨基芴(2-acetaminofluorene, 2-AAF),研究L02细胞移植到具有正常免疫性的大鼠肝内的存活与增殖情况．方法:SD大鼠出生前宫内ip正常人L02肝细胞,诱导胎鼠对L02肝细胞产生免疫耐受,出生2 wk时分别ip小(1．2 mg／kg)、中(13 mg／kg)、大剂量(30 mg／kg)2-乙酰氨基芴或生理盐水,隔日行2／3肝切除术,同时经脾移植DiI染色后的人L02肝细胞,建立2-AAF／PH肝细胞增殖模型．采用免疫荧光、RT-PCR、免疫组化、DiI荧光示踪等方法,在不同时相分别检测人白蛋白、人白蛋白mRNA、增殖细胞核抗原(PCNA)以及在荧光显微镜下观察人L02肝细胞在鼠肝内的分布,并采用计算机图像分析系统分析不同时相PCNA阳性细胞的数密度和面积密度．结果:2-乙酰氨基芴实验组(小、中、大剂量)的各项检测,均与对照组无明显区别;于移植后1,2,4,6,8,10 wk在荧光显微镜下观察到人L02肝细胞在鼠肝内的动态分布;移植后2, 4,6,8 wk大鼠均检测出人白蛋白及人白蛋白mRNA;移植后2,4,6 wk检测出特异性人增殖细胞核抗原PCNA,移植后1,2,4,6,8 wk检测出非特异性PCNA．结论:2-AAF／PH模型中,2-乙酰氨基芴对移植L02细胞无明显增殖作用;L02细胞在2-乙酰氨基芴处理人鼠嵌合肝动物模型中存活10 wk,产生白蛋白功能持续8 wk．     

Studies of liver repopulation using the dipeptidyl peptidase IV-deficient rat and other rodent recipients: Cell size and structure relationships regulate capacity for increased transplanted hepatocyte mass in the liver lobule

The feasibility of liver repopulation with hepatocytes has been shown, although clinical applications demand significant hepatic replacement. To show whether portal vascular bed in large animals could accomodate a greater cell number, we analyzed liver repopulation in syngeneic Fischer 344 rats deficient in dipeptidyl peptidase IV. This system allowed localization of transplanted normal hepatocytes in liver or various ectopic sites, as well as dual studies for analysis of gene expression. Interestingly, the product of a dipeptidyl peptidase IV substrate inactivated bile canalicular adenosine triphosphatase (ATPase) activity in normal but not in dipeptidyl peptidase IV- deficient rats, which allowed localization of dipeptidyl peptidase IV- deficient hepatocytes in normal rat liver for additional reversed transplantation systems. Further studies with genetically marked cells showed that because of the size difference between hepatocytes and portal vein radicles, intrasplenically transplanted cells were distributed in periportal areas (zone 1) in mice, whereas in larger animals (rats or rabbits) cells were also distributed downstream to midlobular (zone 2) or perivenous (zone 3) areas. Transplantation of an escalating number of hepatocytes showed that adult rats tolerated intrasplenic injection of a large cell number in single sessions (up to 1 X 10⁸, approximately 10% to 15% of the host hepatocyte mass). Morphometric analysis of recipient livers showed survival of a significantly greater cell number with incorporation in host liver plates. At 4 weeks, transplantation of 2 x 10⁷ hepatocytes into adult rats led to a survival of 1.4 +/- 1.0 x 10⁶ transplanted cells/cm3 liver, whereas after transplantation of 5 x 10⁷ cells or 7.5 x 10⁷ cells, the number of surviving transplanted cells in the liver significantly increased to 4.1 +/- 1.4 x 10⁶ transplanted cells/cm3 liver (mean, 2.9-fold; P<.003) and 5.5 +/- 1.3 x 10⁶ transplanted cells/cm3 liver (mean, 3.9-fold; P<.003), respectively. When cells were injected in greater numbers, transplanted hepatocytes retained normal function and produced more serum albumin or hepatitis B surface antigen in deficient hosts. These data indicate the feasibility in larger animals of significant liver repopulation with hepatocyte transplantation. Use of dipeptidyl peptidase IV-deficient rats should help further analysis of mechanisms in liver repopulation. (Hepatology 1996 Mar;23(3):482-96)     

Ectopic transplantation of hepatocyte sheets fabricated with temperature‐responsive culture dishes

Aim: Hepatocyte transplantation to host livers by single cell suspension injection from the portal vein has been clinically successful in cases where the host liver architecture is intact. However, further investigation is still needed to achieve regeneration of the liver architecture when the host liver is destroyed, since single cell suspension injection often results in the formation of small hepatocyte colonies or islands. We show a hepatocyte transplantation strategy to ectopic sites. Methods: Primary hepatocytes isolated from green fluorescent protein (GFP)‐transgenic rats were cultured on temperature‐responsive culture dishes. After harvest as intact cell sheets, triple‐layered cell sheets were transplanted over the superficial caudal epigastric artery and vein of athymic rats which had operation of 70% partial hepatectomy. Results: The transplanted hepatocytes were integrated to host tissue with a laminar cell arrangement at transplanted sites within one week after surgery. But the transplanted hepatocytes were hardly detected four weeks after transplantation, when the partially hepatectomized host liver was completely regenerated. GFP‐positive bile duct‐like tubes and functional blood vessels were observed. Conclusion: These results imply the usefulness of hepatocyte sheets in ectopic transplantation, as well as the need of trophic factors for hepatocyte survival.     

新生大鼠肝细胞脾内移植联合鼠肝再生增强因子治疗大鼠急性肝衰竭的疗效与免疫学机制

目的探讨新生大鼠肝细胞脾内移植联合重组鼠肝再生增强因子（rALR）治疗大鼠急性肝衰竭的疗效与免疫学机制。方法采用D-氨基半乳糖（1．2 g／kg）诱导并建立大鼠急性肝衰竭模型,36 h后随机分为6组：Ⅰ组：模型对照组;Ⅱ组：经脾脏注射等渗盐水1 ml,腹腔注射等渗盐水1 ml／d;Ⅲ组：经脾脏注射rALR 1 ml（50μg／kg）,腹腔注射rALR 1 ml（50μg·kg^-1·d^-1）;Ⅳ：经脾脏移植2×10^7同种异体新生大鼠肝细胞,腹腔注射等渗盐水1 ml／d;Ⅴ组：经脾脏移植2×10^7同种异体新生大鼠肝细胞,腹腔注射rALR 1 ml（50μg·kg^-1·d^-1）;Ⅵ组：经脾脏移植2×10^7同种异体新生大鼠肝细胞,腹腔注射环孢菌素1 ml（10 mg·kg^-1·d^-1）。观察大鼠每天存活率;术后第1、5天及2周处死大鼠以获取肝、脾组织,观察脾内移植肝细胞的组织学改变;在术前、术后第1、2、5、12天采集静脉血,采用放射免疫法测定血清IL-1β和TNFα的浓度。结果Ⅰ、Ⅱ和Ⅲ组大鼠存活时间差异无统计学意义,Ⅳ组有部分大鼠长期存活,2周存活率为33％,Ⅴ组大鼠2周存活率显著高于Ⅳ组,而与Ⅵ组大鼠2周存活率比较差异无统计学意义。Ⅳ、Ⅵ组脾内移植的肝细胞可存活5～7 d,Ⅴ组脾内移植肝细胞可存活至2周以上。术后第1天,Ⅳ组血清IL-1β水平显著高于Ⅴ组和Ⅵ组（P〈0．05）;术后第5天,Ⅳ组血清IL-1β水平仅与Ⅵ组差异有统计学意义（P〈0．05）。术后第1天,TNFα的浓度在Ⅱ组显著高于Ⅳ、Ⅴ、Ⅵ组（P〈0．05）。结论新生大鼠肝细胞脾内移植与rALR联合治疗大鼠急性肝衰竭有一定疗效,可提高D-氨基半乳糖诱导肝衰竭大鼠的存活率;移植肝细胞在脾脏可存活2周以上,其机制可能与促进肝细胞再生、预防移植肝细胞凋亡及轻微抑制细胞免疫有关。     

Human hepatocytes transplanted into genetically immunocompetent rats are susceptible to infection by hepatitis B virus in situ

Immune tolerance of human cells without generalized immunosuppression was created in groups of normal fetal rats at 17 days of gestation by inoculation ip with primary human hepatocytes in utero. One day after birth, suspensions of human hepatocytes were transplanted via intrasplenic injection and one week later groups of rats were inoculated with hepatitis B virus (HBV). Tolerized rats that were transplanted with human hepatocytes and subsequently infected with HBV produced hepatitis B surface antigen (HBsAg) in serum beginning on day 3. Levels rose fivefold and remained stable at 0.75 pg/ml through at least 60 days. Of cells that stained positive for human serum albumin, approximately 30% were found to be also positive for HBsAg by immunohistochemistry. Serum HBV DNA was detectable from 1 to 15 weeks postinfection. Finally, covalently closed circular DNA, reflecting HBV replication, was found in liver and serum. Controls that were tolerized and not transplanted, but inoculated with HBV, as well as untreated controls, had no evidence of HBV gene expression or replication under identical conditions. The data support the conclusion that primary human hepatocytes transplanted into genetically immunocompetent rodent hosts, survive and maintain sufficient differentiation to produce human serum albumin and be infected by HBV.     

L02细胞建立人鼠嵌合肝动物模型

目的:研究L02细胞移植到具有正常免疫活性的大鼠肝内的存活情况.方法:SD大鼠出生前宫内腹腔注射正常人L02肝细胞,诱导胎鼠对人L02肝细胞产生免疫耐受,出生2wk时经脾移植DiI染色后的人L02肝细胞,建立人鼠嵌合肝动物模型.采用免疫荧光、SP免疫组化、DiI荧光示踪等方法,分别检测人白蛋白、特异性人增殖细胞核抗原PCNA(proliferatingcellnuclearantigen)以及在荧光显微镜下观察人L02肝细胞在鼠肝内的分布.结果:于移植后1,2,4,6,8,10wk在荧光显微镜下观察到人L02肝细胞在鼠肝内的动态分布;移植后2,4,6,8wk大鼠均检测出人白蛋白,4wk时分泌最多;移植后2,4,6wk检测出特异性人增殖细胞核抗原PCNA,以4wk发现PCNA阳性细胞最多.结论:移植的人L02肝细胞在具有正常免疫活性的免疫耐受鼠体内能够存活、增殖,并产生人白蛋白.     

Cryopreserved mouse hepatocytes retain regenerative capacity in vivo

BACKGROUND & AIMS: Substitution of hepatocyte transplantation for whole liver transplants in selected individuals with liver disease could significantly expand the number of patients to benefit from use of scarce donor livers. However, successful hepatocyte transplantation may require that donor cells retain normal functional and proliferative capabilities and that they be readily available. Banking of cryopreserved hepatocytes would fulfill the latter requirement. Cryopreservation protocols have been developed that minimize hepatocyte injury and allow preservation of metabolic activity. The aim of this study was to assess cryopreserved hepatocyte proliferative capacity in vivo after thawing. METHODS: Fresh and frozen/thawed mouse hepatocytes were transferred separately into the livers of recipient mice with transgene-induced liver disease, an environment that is permissive for clonal expansion of donor cell populations. Fresh and cryopreserved donor cells were compared for their ability to proliferate and replace damaged parenchyma. RESULTS: Although cryopreservation decreased hepatocyte viability, individual viable frozen/thawed hepatocytes demonstrated clonal replicative potential identical to that of fresh hepatocytes. Even after storage for 32 months in liquid nitrogen, transplanted hepatocytes constituting 0.1% of total adult hepatocyte number could repopulate a mean of 32% of recipient liver parenchyma. CONCLUSIONS: These findings suggest that cryopreserved hepatocytes represent an appropriate source of cells for therapeutic hepatocyte transplantation.     

Functional integration of hepatocytes derived from human mesenchymal stem cells into mouse livers

AIMS: At present, clinical success of hepatocyte transplantation as an alternative to whole liver transplantation is hampered by the limited availability of suitable donor organs for the isolation of transplantable hepatocytes. Hence, novel cell sources are required to deliver hepatocytes of adequate quality for clinical use. Mesenchymal stem cells (MSCs) from human bone marrow may have the potential to differentiate into hepatocytes in vitro and in vivo. METHODS: Isolated MSCs were selected by density gradient centrifugation and plastic adherence, differentiated in the presence of human hepatocyte growth medium and transplanted in immunodeficient Pfp/Rag2 mice. RESULTS: Here, we demonstrate that human MSCs gain in vitro the characteristic morphology and function of hepatocytes in response to specified growth factors. Specifically, preconditioned MSCs store glycogen, synthesise urea and feature the active hepatocyte-specific gene promoter of phosphoenolpyruvate carboxykinase (PCK1). After transplantation into livers of immunodeficient mice, preconditioned MSCs engraft predominantly in the periportal portion of the liver lobule. In situ, the cells continue to store glycogen and express PCK1, connexin32, albumin and the human hepatocyte-specific antigen HepPar1, indicating that the transplanted cells retain prominent qualities of hepatocytes after their regional integration. CONCLUSION: MSCs derived from human bone marrow may serve as a novel source for the propagation of hepatocyte-like cells suitable for cell therapy in liver diseases.     

骨髓干细胞在大鼠肝再生环境中的分化

研究大鼠骨髓干细胞在部分肝切除后肝再生环境中的分化。从部分肝切除模型大鼠的胫骨中提取骨髓细胞,应用流式细胞仪富集骨髓干细胞,以PKH26-GL体外标记后通过门静脉进行自体移植,2周后行白蛋白和角蛋白8免疫组化检查。结果肝板肝细胞间PKH26-GL标记骨髓干细胞表达白蛋白、角蛋白8。提示骨髓干细胞在部分肝切除后肝再生环境中能分化为肝细胞,骨髓干细胞可能参与部分肝切除后的肝再生过程。     

肝再生大鼠血清诱导骨髓干细胞向肝细胞分化的实验研究

目的观察肝大部切除大鼠再生血清和肝细胞生长因子(HGF)诱导骨髓干细胞向肝实质细胞分化的作用；探讨骨髓干细胞向肝细胞分化和增殖的体外培养条件和方法，为患者应用自身骨髓细胞修复损伤肝脏提供实验依据。方法制作肝大部切除大鼠肝再生动物模型，收集术后24h血清；分别应用鼠肝再生血清和HGF对大鼠骨髓细胞进行定向诱导分化培养；以免疫组化、RTPCR和western blot等方法对分化不同阶段细胞进行检测。将分化细胞经尾静脉输入同系大鼠，观察输注细胞在肝、脾内的生长情况。结果活体移植分化细胞能定向迁移至肝和脾；体外及体内分化细胞在mRNA水平和蛋白质水平均表达白蛋白，并在一定时期内表达甲胎蛋白。结论大鼠骨髓干细胞在肝大部切除再生血清或HGF的诱导下能横向分化为肝实质样细胞。     

Normal hepatocytes correct serum bilirubin after repopulation of Gunn rat liver subjected to irradiation/partial resection

The treatment of inherited metabolic liver diseases by hepatocyte transplantation (HT) would be greatly facilitated if the transplanted normal hepatocytes could be induced to proliferate preferentially over the host liver cells. We hypothesized that preparative hepatic irradiation (HIR) should inhibit host hepatocyte proliferation in response to partial hepatectomy (PH). Normal nonirradiated hepatocytes transplanted in this setting should have a selective growth advantage over the host liver cells and should progressively repopulate the liver. To test this hypothesis, we transplanted 5 million hepatocytes from normal Wistar-Roman High Avoidance (RHA) rats into the livers of congeneic bilirubin-uridine 5'-diphosphoglucuronate glucuronosyltransferase (UGT1A1)-deficient jaundiced Gunn rats by intrasplenic injection after one of the following treatments: (1) 68% PH, (2) HIR (50 Gy), or (3) HIR + PH. In rats receiving either PH or HIR alone before HT, serum bilirubin concentrations declined by 25% to 30% in 28 weeks. In contrast, serum bilirubin levels were normalized completely in rats receiving HIR + PH before HT. Massive repopulation of the Gunn rat liver by the UGT1A1-positive Wistar-RHA hepatocytes was shown by UGT1A1 enzyme assay, immunoblot analysis, and immunohistochemical staining of the recipient liver. High-performance liquid chromatography analysis of the bile collected from Gunn rats 5 months after PH, HIR, and HT showed normalization of the pigment profile, with bilirubin diglucuronide and monoglucuronide as the predominant pigments. In conclusion, a preparative regimen of HIR + PH results in massive repopulation of the liver with functionally normal transplanted hepatocytes, resulting in complete correction of a metabolic deficiency. Noninvasive strategies to replace PH for providing proliferative stimuli to the transplanted cells should make this regimen valuable in augmenting the effects of HT for the treatment of liver diseases.