Bone marrow derivation of pericryptal myofibroblasts in the mouse and human small intestine and colon

BACKGROUND AND AIMS: In order to establish whether extraintestinal cells contribute to the turnover and repair of gastrointestinal tissues, we studied the colons and small intestines of female mice that had received a male bone marrow transplant, together with gastrointestinal biopsies from female patients that had developed graft versus host disease after receiving a bone marrow transplant from male donors. METHODS: Using in situ hybridisation to detect Y chromosomes and immunohistochemistry, we demonstrated that cells derived from injected bone marrow frequently engrafted into the intestine and differentiated into pericryptal myofibroblasts. RESULTS: In the human intestine, we confirmed by combining in situ hybridisation with immunostaining for smooth muscle actin that the bone marrow derived cells within the intestine exhibited a myofibroblast phenotype. In female mouse recipients of male bone marrow grafts, we observed colocalisation of Y chromosomes and clusters of newly formed marrow derived myofibroblasts. While few of these were present at seven days after bone marrow transplantation, they were numerous at 14 days, and by six weeks entire columns of pericryptal myofibroblasts could be seen running up the sides of crypts in both the small intestine and colon. These columns appeared to extend into the villi in the small intestine. Within the intestinal lamina propria, these Y chromosome positive cells were negative for the mouse macrophage marker F4/80 antigen and CD34. CONCLUSIONS: Bone marrow derived pericryptal myofibroblasts were present in the mouse intestine following irradiation and bone marrow transplant, and in the intestines of human patients suffering graft versus host disease following a bone marrow transplant. Our data indicate that bone marrow cells contribute to the regeneration of intestinal myofibroblasts and epithelium after damage, and we suggest that this could be exploited therapeutically.     

Resolution of chronic hepatitis B and anti-HBs seroconversion in humans by adoptive transfer of immunity to hepatitis B core antigen

BACKGROUND & AIMS: Impaired T-cell reactivity is believed to be the dominant cause of chronic hepatitis B virus (HBV) infection. We characterized HBV-specific T-cell responses in chronic hepatitis B surface antigen carriers who received bone marrow from HLA-identical donors with natural immunity to HBV and seroconverted to antibody to hepatitis B surface antigen. METHODS: T-cell reactivity to HBV antigens and peptides was assessed in a proliferation assay, the frequency of HBV core- and surface-specific T cells was quantified directly by ELISPOT assays, and T-cell subsets were analyzed by flow cytometry. RESULTS: CD4+ T-cell reactivity to HBV core was common in bone marrow donors and the corresponding recipients after hepatitis B surface antigen clearance, whereas none reacted to surface, pre-S1, or pre-S2 antigens. Furthermore, CD4+ T cells from donor/recipient pairs recognized similar epitopes on hepatitis B core antigen; using polymerase chain reaction for the Y chromosome, the recipients' CD4+ T lymphocytes were confirmed to be of donor origin. The frequency of core-specific CD4+ and CD8+ T cells was several-fold higher than those specific for surface antigen. CONCLUSIONS: This study provides the first evidence in humans that transfer of hepatitis B core antigen-reactive T cells is associated with resolution of chronic HBV infection. Therapeutic immunization with HBV core gene or protein deserves further investigation in patients with chronic hepatitis B.     

Repopulation of liver endothelium by bone-marrow-derived cells

The mechanism underlying the immunological advantage of hepatic allografts relative to other organs is incompletely understood. We used molecular probes for the repetitive units on the Y chromosome, to identify an increasing number of male liver venous endothelial cells in needle biopsy samples of men who received female donor liver grafts. We have also shown repopulation of liver endothelium by bone marrow derived cells in a male to female mouse bone marrow transplant model. We conclude that the liver has unique venous endothelium characterised by turnover and replacement by bone marrow derived cells.     

What's new in liver fibrosis? The origin of myofibroblasts in liver fibrosis

Chronic liver injury of many etiologies produces liver fibrosis and may eventually lead to the formation of cirrhosis. Fibrosis is part of a dynamic process associated with the continuous deposition and resorption of extracellular matrix, mainly fibrillar collagen. Studies of fibrogenesis conducted in many organs including the liver demonstrate that the primary source of the extracellular matrix in fibrosis is the myofibroblast. Hepatic myofibroblasts are not present in the normal liver but transdifferentiate from heterogeneous cell populations in response to a variety of fibrogenic stimuli. Debate still exists regarding the origin of hepatic myofibroblasts. It is considered that hepatic stellate cells and portal fibroblasts have fibrogenic potential and are the major origin of hepatic myofibroblasts. Depending on the primary site of injury the fibrosis may be present in the hepatic parenchyma as seen in chronic hepatitis or may be restricted to the portal areas as in most biliary diseases. It is suggested that hepatic injury of different etiology triggers the transdifferentiation to myofibroblasts from distinct cell populations. Here we discuss the origin and fate of myofibroblast in liver fibrosis.     

Reverse seroconversion of hepatitis B virus infectious status after allogeneic bone marrow transplantation from a carrier donor.

A 35-year-old man with acute promyelocytic leukemia received an allogeneic bone marrow transplant (BMT) in second complete remission. The donor was his 18-year-old brother, a chronic hepatitis B virus (HBV) carrier with detectable serum hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and hepatitis B virus DNA (HBV DNA). Before BMT, the recipient was immune to HBV, with serum antibody to HBsAg (anti-HBs), antibody to HBeAg (anti-HBe) and normal liver function. Examination of the recipient serum drawn 2 months after BMT revealed reverse seroconversion from anti-HBs/anti-HBe to HBsAg/HBeAg, which remained positive thereafter. Upon reducing cyclosporin 6 months after BMT, acute hepatitis occurred with HBV DNA in serum as evidence of active HBV replication; the patient then developed chronic hepatitis which progressed to cirrhosis and hepatic decompensation within 8 months. Transfusion of HBV DNA/HBeAg-positive bone marrow is thus harmful even when the recipient has anti-HBs prior to BMT.     

Origin of leukemic relapse after bone marrow transplantation: comparison of cytogenetic and molecular analyses

Leukemic relapse following bone marrow transplant (BMT) is generally due to the recurrence in recipient cells, but may rarely occur as a result of donor cell transformation. Donor cell relapse is generally identified using cytogenetic markers such as the sex chromosomes. Recently, molecular techniques have been used to identify the origin of bone marrow cells by their DNA restriction fragment length polymorphisms. We describe the case of a male pediatric patient who had a leukemic relapse 30 months following BMT from his sister. Both cytogenetic and molecular techniques were used to identify the origin of the leukemic relapse. Cytogenetic analyses indicated the absence of the Y chromosome and the presence of a donor cell type 9qh polymorphism, suggesting a donor cell relapse. Molecular analyses also indicated the absence of the Y chromosome but demonstrated the recurrence of recipient DNA markers from three other chromosomes, suggesting a recipient cell relapse. While the leukemic cell lineage cannot be definitively assigned in this case, our results suggest that caution must be exercised when assigning leukemic cell lineage following post-BMT relapse.     

Targeting liver myofibroblasts: a novel approach in anti-fibrogenic therapy

Chronic liver disease results in a liver-scarring response termed fibrosis. Excessive scarring leads to cirrhosis, which is associated with high morbidity and mortality. The only treatment for liver cirrhosis is liver transplantation; therefore, much attention has been directed toward therapies that will slow or reverse fibrosis. Although anti-fibrogenic therapies have been shown to be effective in experimental animal models, licensed therapies have yet to emerge. A potential problem for any anti-fibrogenic therapy in the liver is the existence of the body’s major drug metabolising cell (the hepatocyte) adjacent to the primary fibrosis-causing cell, the myofibroblast. This article reviews the development of a human recombinant single-chain antibody (scAb) that binds to the surface of myofibroblasts. This antibody binds specifically to myofibroblasts in fibrotic mouse livers. When conjugated with a compound that stimulates myofibroblast apoptosis, the antibody directs the specific apoptosis of myofibroblasts with greater specificity and efficacy than the free compound. The antibody also reduces the adverse effect of liver macrophage apoptosis and—in contrast to the free compound—reversed fibrosis in the sustained injury model used. These data suggest that specifically stimulating the apoptosis of liver myofibroblasts using a targeting antibody has potential in the treatment of liver fibrosis.     

Short-term study of chimaerism after bone marrow transplantation for severe aplastic anaemia

Chimaerism was studied early (2 weeks to 3 months) during haematopoietic reconstitution after bone marrow transplantation in 18 severe aplastic anaemia patients (acquired SAA: 14 patients; Fanconi anaemia: four patients). Fourteen patients received marrow from an identical sibling donor, one from the phenoidentical father and three from a matched unrelated donor. Peripheral blood cell DNA was first analysed by Southern blotting with a multilocus minisatellite probe (33.6.3) or a Y chromosome specific probe (pHY2.1). For all 14 patients grafted with a genotypically identical sibling donor, the post-graft DNA profile strictly matched the respective donor profile (minisatellite probe) or disclosed the Y chromosome specific band in the case of female patients grafted with a male donor. In contrast, for the one patient grafted in a mismatched situation and for two out of three patients grafted with a matched unrelated donor, the results indicated autologous bone marrow recovery. This difference between patients grafted with an identical sibling donor and those grafted in other situations is statistically significant (P less than 0.01). The 15 patients with circulating cells of donor origin were then studied by polymerase chain reaction amplification of the DNA samples. The three male patients with a female donor were studied by amplification of a Y chromosome specific sequence (DYZ1), allowing the detection of one male cell in 10(4) female cells. In all three cases, residual male nucleated cells were detected. The analysis was performed by amplification of the 33.6.3 minisatellite sequence for the 12 remaining patients. No residual recipient cells were detected within the sensitivity limit of the method which is 1% in that case. This suggests that detection of residual host cells depends on the sensitivity of the technique used.     

The sources of parenchymal regeneration after chronic hepatocellular liver injury in mice

After liver injury, parenchymal regeneration occurs through hepatocyte replication. However, during regenerative stress, oval cells (OCs) and small hepatocyte like progenitor cells (SHPCs) contribute to the process. We systematically studied the intra-hepatic and extra-hepatic sources of liver cell replacement in the hepatitis B surface antigen (HBsAg-tg) mouse model of chronic liver injury. Female HBsAg-tg mice received a bone marrow (BM) transplant from male HBsAg-negative mice, and half of these animals received retrorsine to block indigenous hepatocyte proliferation. Livers were examined 3 and 6 months post-BM transplantation for evidence of BM-derived hepatocytes, OCs, and SHPCs. In animals that did not receive retrorsine, parenchymal regeneration occurred through hepatocyte replication, and the BM very rarely contributed to hepatocyte regeneration. In mice receiving retrorsine, 4.8% of hepatocytes were Y chromosome positive at 3 months, but this was frequently attributable to cell fusion between indigenous hepatocytes and donor BM, and their frequency decreased to 1.6% by 6 months, as florid OC reactions and nodules of SHPCs developed. By analyzing serial sections and reconstructing a 3-dimensional map, continuous streams of OCs could be seen that surrounded and entered deep into the nodules of SHPCs, connecting directly with SHPCs, suggesting a conversion of OCs into SHPCs. In conclusion, during regenerative stress, the contribution to parenchymal regeneration from the BM is minor and frequently attributable to cell fusion. OCs and SHPCs are of intrinsic hepatic origin, and OCs can form SHPC nodules.     

Bone marrow engraftment in a rodent model of chemical carcinogenesis but no role in the histogenesis of hepatocellular carcinoma

BACKGROUND AND AIM: Recent studies indicated that hepatic stem cells in the bone marrow could differentiate into mature hepatocytes, suggesting that bone marrow cells could be used for replacement of damaged hepatocytes in a variety of liver diseases. Hepatocellular carcinoma (HCC) is thought to arise from hepatic stem cells. In this study, we investigated the malignant potential of hepatic stem cells derived from the bone marrow in a mouse model of chemical hepatocarcinogenesis. METHODS: Bone marrow cells were obtained from the male beta-galactosidase (beta-gal) transgenic mouse and transplanted into female recipient mice. Hepatocarcinogenesis was induced by a year of treatment with diethylnitrosamine and phenobarbital (NDEA/PB). One year later, the liver was removed from each treated mouse and evaluated by x-gal staining, immunohistochemistry, and fluorescence in situ hybridisation (FISH). RESULTS: Forty per cent of recipient mice survived and developed multiple HCC. Clusters of beta-gal positive mature hepatocytes were detected sporadically in the entire liver of NDEA/PB treated mice who underwent bone marrow transplantation (BMT) with while no such hepatocytes were identified in the liver of BMT mice that were not treated with NDEA/PB. The Y chromosome was detected with the same frequency as the donor male liver in clusters of beta-gal positive mature hepatocytes by FISH. However, no HCC was positive for beta-gal or the Y chromosome. Immunohistochemically, beta-gal positive mature hepatocytes did not express CD34 or alpha-fetoprotein. CONCLUSIONS: Our results suggest that hepatic stem cells derived from the bone marrow have low malignant potential, at least in our model.     

Analysis of Biliary Epithelial-Mesenchymal Transition in Portal Tract Fibrogenesis in Biliary Atresia

Background  

The cellular origin of myofibroblast in the liver fibrosis remains unclear. This study was designed to investigate whether biliary epithelial cells (BECs) undergoing epithelial–mesenchymal transition (EMT) might be found in patients with biliary atresia, thereby serving as a source of fibrotic myofibroblasts.     

A preliminary study of liver cells derived from bone marrow

OBJECTIVE: To investigate whether hepatocytes can be derived from bone marrow cells in vivo. METHODS: A cohort of lethally irradiated BALB/C female mice received whole bone marrow transplants from age‐matched male donors and were killed at 1, 2, 4 and 8 weeks post transplantation. Fluorescence in situ hybridization (FISH) for the Y‐chromosome was performed using liver tissue. RESULTS: A few Y‐chromosome positive hepatocytes were found in the liver tissues at 2 months post transplantation. CONCLUSION: Hepatocytes can be derived from bone marrow cells after transplantation in lethally irradiated mice without severe acute hepatic injury.     

拉米夫定、阿德福韦酯联合自体骨髓干细胞移植治疗乙肝肝硬化失代偿期患者的疗效观察

目的观察拉米夫定、阿德福韦酯联合自体骨髓干细胞移植治疗乙肝肝硬化失代偿期患者的临床效果。方法77例乙肝肝硬化失代偿期患者随机分为两组。常规对症支持治疗方法下,A组（37例）采用拉米夫定、阿德福韦酯抗病毒治疗,B组（40例）在A组基础上加用自体骨髓干细胞移植治疗。治疗4周后复查各实验室指标、l临床症状和体征情况。结果治疗4周后,B组血浆白蛋白、天门冬氨酸氨基转移酶（AST）、丙氨酸氨基转移酶（ALT）、总胆红素水平、PT、AFP、胆碱酯酶等指标较A组明显改善（P〈0．05）;B组临床症状和体征较A组也明显改善（P〈0．05）。结论采用拉米夫定、阿德福韦酯联合自体骨髓干细胞移植治疗乙肝肝硬化失代偿期患者,可有效避免骨髓干细胞受到患者体内乙肝病毒的感染和损害,帮助骨髓干细胞在肝脏环境内能分化为正常的肝细胞,参与肝脏结构的修复和重构,改善患者的肝功能,提高患者的生活质量。     

Cytogenetic evidence for recurrence of acute myelogenous leukemia after allogeneic bone marrow transplantation in donor hematopoietic cells.

A 22-yr-old man with acute myelocytic leukemia received a bone marrow transplant from a genotypically HLA-identical female sibling after cyclophosphamide preparation. He remained in complete remission for 18 mo, when he developed a chloroma in the perineum. The chloroma was treated with local radiotherapy. The chloroma recurred 8 mo later and was treated with radiotherapy followed by combination chemotherapy. At 34 mo after transplant, marrow relapse and chloroma were documented. The first chloroma contained host cells by fluorescent Y-chromatin body analyses of interphase nuclei. All metaphase cells and karyotypes from peripheral blood and marrow samples showed no evidence of host cells from 3 wk after transplant through the time of marrow relapse. Data from autosomal and sex chromosome studies indicate that the marrow relapse occurred in cells of donor origin. A new consistent chromosome abnormality [45, X, -X, t(8;21) (q22; q22)] was observed in a majority of donor cells. The patient received a second bone marrow transplant from the same donor after preparation with busulfan and cyclophosphamide and attained a complete remission with full hematologic engraftment.     

肝脏瞬时弹性值评估慢性乙型肝炎肝纤维化程度及肝脏储备功能的临床研究

目的探讨慢性乙型肝炎(CHB)患者FibroScan与肝组织纤维化面积之间的相关性,以评价FS值对肝纤维化程度测定的意义,分析乙型肝炎后肝硬化患者的FS值变化与肝脏储备功能评价系统CTP分级的关系。方法前瞻性研究正常对照组30例、肝病组113例(CHB患者62例及其所致肝硬化患者51例)FS值,对研究对象行腹部B超检查后,应用肝脏瞬时弹性超声进行FS值测定,收集肝硬化患者入院24 h内的临床资料,计算CTP分值,根据评分分为A、B、C 3级,同时采用计算机辅助数字图像分析法检测肝组织标本的纤维化程度,分析肝病组FS值与肝纤维化面积之间的相关性以及肝硬化患者FS值变化与CTP分级的关系。结果 (1)CHB患者组的FS值与正常对照组比较,肝硬化患者的FS值与CHB组比较,差异均有统计学意义(P<0.05);(2)在肝硬化组中FS值随着CTP分级升高而升高,ChildA、B、C 3组之间FS值差异均有统计学意义(P<0.05);肝病组的FS值与肝纤维化面积有显著的线性正相关性,且相关系数较高(r=0.804,P<0.01)。结论 FS弹性值与肝纤维化面积有很好的相关性,肝硬化患者的FS值随着CTP分级的上升而增加,FS值可以评估CHB肝纤维化程度,在一定程度上可以评估肝硬化患者的肝脏储备功能。     

骨髓来源肝细胞的初步研究

目的 验证骨髓细胞是否可以转化为肝细胞。方法 通过放射致死剂量照射的BALB/C雌性小鼠接受周龄相配的同系雄性小鼠的全骨髓移植后，分别在移植后1，2，4周和2个月分批处死移植存活的小鼠。分别在游离的肝细胞和肝脏的石蜡切片上用荧光原位杂交法检测Y染色体阳性肝细胞。结果 在移植后2个月的小鼠肝脏游离细胞和石蜡切片上均发现有Y染色体阳性肝细胞，数量极少，但确实存在。结论 在接受放射致死剂量照射但没有导致严重的急性肝脏损伤情况下，骨髓细胞可以转化为成熟的肝细胞。     

Recent advancement of molecular mechanisms of liver fibrosis

Liver fibrosis occurs in response to any etiology of chronic liver injury including hepatitis B and C, alcohol consumption, fatty liver disease, cholestasis, and autoimmune hepatitis. Hepatic stellate cells (HSCs) are the primary source of activated myofibroblasts that produce extracellular matrix (ECM) in the liver. Various inflammatory and fibrogenic pathways contribute to the activation of HSCs. Recent studies also discovered that liver fibrosis is reversible and activated HSCs can revert to quiescent HSCs when causative agents are removed. Although the basic research for liver fibrosis has progressed remarkably, sensitive and specific biomarkers as non‐invasive diagnostic tools, and effective anti‐fibrotic agents have not been developed yet. This review highlights the recent advances in cellular and molecular mechanisms of liver fibrosis, especially focusing on origin of myofibroblasts, inflammatory signaling, autophagy, cellular senescence, HSC inactivation, angiogenesis, and reversibility of liver fibrosis.     

Natural history of hepatitis C following liver transplantation

PURPOSE OF REVIEW: Currently, chronic hepatitis C virus-infection-related cirrhosis is the most common indication for liver transplantation in the USA and most parts of the world. While the incidence of new hepatitis C virus cases has decreased, the prevalence of infection will not peak until the year 2040. In addition, as the duration of infection increases, the proportion of new patients with cirrhosis will double by 2020 in an untreated patient population. If this model is correct, the projected increase in the need for liver transplantation secondary to chronic hepatitis C virus infection will place an impossible burden on an already limited supply of organs. In this article we present a comprehensive review of post-transplant hepatitis C virus infection and address the major challenges that face the transplant community. RECENT FINDINGS: Hepatitis C virus infection recurs virtually in every post-transplant patient. Typically, serum levels of hepatitis C virus RNA increase rapidly from week 2 post-liver transplant, achieving 1-year post-liver transplant levels that are 10-20-fold greater than the mean pre-liver transplant levels. Progression of chronic hepatitis C virus is more aggressive after liver transplantation with a cumulative probability of developing graft cirrhosis estimated to reach 30% at 5 years. Approximately 10% of the patients with recurrent disease will die or require re-transplantation within 5 years post-transplantation. Interventions to prevent, improve, or halt the recurrence of hepatitis C virus infection have been evaluated by multiple small studies worldwide with similar overall rates of virological clearance of approximately 9-30%. Current consensus recommends combination therapy with pegylated interferon and ribavirin for those patients with histological recurrence of hepatitis C virus infection and fibrosis of >/= 2/4. Therapy is adjusted to tolerance and rescued with granulocyte colony-stimulating factor and erythropoietin for bone marrow suppression. SUMMARY: The major challenges that face the transplant community in the coming years include new strategies to meet the growing demand for limited organ donor supplies and improvement of treatment for those patients in whom recurrence of viral disease has occurred. Only with improved antiviral treatments and strategies will we make a significant impact on this problem.