Current status of the organ replacement approach for malignancies and an overture for organ bioengineering and regenerative medicine

Significant achievements in the organ replacement approach for malignancies over the last 2 decades opened new horizons, and the age of “Transplant Oncology” has dawned. The indications of liver transplantation for malignancies have been carefully expanded by a strict patient selection to assure comparable outcomes with non-malignant diseases. Currently, the Milan criteria, gold standard for hepatocellular carcinoma, are being challenged by high-volume centers worldwide. Neoadjuvant chemoradiation therapy and liver transplantation for unresectable hilar cholangiocarcinoma has been successful in specialized institutions. For other primary and metastatic liver tumors, clinical evidence to establish standardized criteria is lacking. Intestinal and multivisceral transplantation is an option for low-grade neoplasms deemed unresectable by conventional surgery. However, the procedure itself is in the adolescent stage. Solid organ transplantation for malignancies inevitably suffers from “triple distress,” i.e., oncological, immunological, and technical. Organ bioengineering and regenerative medicine should serve as the “triple threat” therapy and revolutionize “Transplant Oncology.”     

我国器官移植中的伦理困境及解决思路

我国的器官移植近10年来有了发展,无论从技术层面、移植数量和质量、临床管理以及法规建设上都有了长足的进步。然而,由于我们在开展器官移植方面的先天不足,例如从事器官移植的技术队伍主要是来自海外学成归来的专家;技术主要靠引进西方的临床技术,在基础研究和创新方面相对薄弱;在法律和管理制度的建设方面相对滞后,没有建立一个从制度上保证器官移植健康开展的系统,使得在器官供体来源和器官的公正分配上存在许多欠缺。因此有必要对我国的器官移植历史进行回顾和总结,对我国在器官移植中存在的错误观念和伦理困境进行剖析,寻找适合我国开展器官移植的正确途径,促进我国的器官移植事业健康发展。     

Liver metastases and SBRT: A new paradigm?

BackgroundThe outstanding innovations made by early diagnosis, novel surgical techniques, effective chemotherapy regimens and conformal radiotherapy, have significantly improved patients overall survival and quality of life. Multidisciplinary approach to cancer has also led to an increased prevalence of patients with few, organ-confined metastases, who can experience long-term survival even if their disease is no longer localized. Liver is one of the most common site for metastatic disease from several cancers, and when metastatic disease is confined to liver, given the ability of this organ to regenerate almost to its optimal volume, surgical resection represents the standard of care because is associated with a better prognosis. Approximately 70–90% of liver metastases, however, are unresectable and a safe, effective alternative therapeutic option is necessary for these patients.Materials and methodsA review of the current literature was performed to analyze the role of SBRT in treating liver metastases from different cancers. A literature search using the terms “SBRT” and “liver metastases” was carried out in PUBMED.ResultsStereotactic body radiation therapy has shown to provide promising results in the treatment of liver metastases, thanks to the ability of this procedure to deliver a conformal high dose of radiation to the target lesion and a minimal dose to surrounding critical tissues.ConclusionStereotactic body radiation therapy is a non-invasive, well-tolerated and effective treatment for patients with liver metastases not suitable for surgical resection.     

Exploiting the unique regenerative capacity of the liver to underpin cell and gene therapy strategies for genetic and acquired liver disease

The number of genetic or acquired diseases of the liver treatable by organ transplantation is ever-increasing as transplantation techniques improve placing additional demands on an already limited organ supply. While cell and gene therapies are distinctly different modalities, they offer a synergistic alternative to organ transplant due to distinct architectural and physiological properties of the liver. The hepatic blood supply and fenestrated endothelial system affords relatively facile accessibility for cell and/or gene delivery. More importantly, however, the remarkable capacity of hepatocytes to proliferate and repopulate the liver creates opportunities for new treatments based on emerging technologies. This review will summarise current understanding of liver regeneration, describe clinical and experimental cell and gene therapeutic modalities and discuss critical challenges to translate these new technologies to wider clinical utility.This article is part of a Directed Issue entitled: “Regenerative Medicine: the challenge of translation”.     

The use of a supercooling refrigerator improves the preservation of organ grafts

Current medical transplantation confronts major problems such as the shortage of donors and geographical restrictions that inhibit efficient utilization of finite donor organs within their storage lives. To overcome these issues, expanding organ preservation time has become a major concern. We investigated whether a strategy which best preserves organ grafts can be achieved by the use of a newly developed refrigerating chamber, which is capable of establishing a supercooled and unfrozen state stably by generating an electrostatic field in its inside. When adult rat organs such as heart, liver, and kidneys were stored in the supercooled conditions, the levels of major biochemical markers leaked from the preserved organs were significantly lower than in the ordinary hypothermic storage. No apparent tissue damages were observed histologically after the supercooled preservation. Our results suggest that the use of this supercooling refrigerator improves organ preservation and may provide an innovative technique for human organ transplantation.     

Compelled organ donation

Along with ethical considerations, compelling an individual to donate organs, tissues, or bodily fluids brings several legal doctrines into conflict. The privacy of one's body is generally considered sacrosanct by American courts, which have upheld a competent adult's right to refuse medical procedures, even in cases when they are necessary to save the life of another. Although medical and legal communities stress “respect for the individual” as being paramount under American jurisprudential principles, the doctrine of “substituted judgment” permits a court to act (for example, by consenting to organ donation) on behalf of an incompetent individual or child. Parents also have the right to cause a child to “donate” an organ, and although a means exists by which the child can refuse, this may not be realistically feasible for young children. The revised Uniform Anatomical Gift Act of 2006, while clarifying issues of who may make organ donation decisions, does not resolve all the practical issues of compelled organ donation for minors.     

Autologous hematopoietic stem cell transplantation for systemic sclerosis

Systemic sclerosis is a rare disorder manifesting as skin and internal organ fibrosis, a diffuse vasculopathy, inflammation, and features of autoimmunity. Patients with diffuse cutaneous disease or internal organ involvement have a poor prognosis with high mortality. To date no therapy has been shown to reverse the natural course of the disease. Immune suppressive drugs are commonly utilized to treat patients, but randomized trials have generally failed to demonstrate any long-term benefit. In phase I/II trials, autologous hematopoietic stem cell transplantation (HSCT) has demonstrated impressive reversal of skin fibrosis, improved functionality and quality of life, and stabilization of internal organ function, but initial studies were complicated by significant treatment-related mortality. Treatment-related mortality was reduced by better pre-transplant evaluation to exclude patients with compromised cardiac function and by treating patients earlier in disease, allowing selected patients the option of autologous HSCT treatment. There are currently three ongoing randomized trials of autologous HSCT for systemic sclerosis: ASSIST (American Systemic Sclerosis Immune Suppression versus Transplant), SCOT (scleroderma cyclophosphamide versus Transplant), and ASTIS (Autologous Stem cell Transplantation International Scleroderma). The results from these trials should clarify the role of autologous HSCT in the currently limited therapeutic arsenal of severe systemic sclerosis.     

Donor derived malignancy following transplantation: a review

Organ and tissue transplant is now the treatment of choice for many end stage diseases. In the recent years, there has been an increasing demand for organs but not a similar increase in the supply leading to a severe shortage of organs for transplant resulted in increasing wait times for recipients. This has resulted in expanded donor criteria to include older donors and donors with mild disease. In spite of implementation of more stringent criteria for donor selection, there continues to be some risk of donor derived malignancy. Malignancy after transplantation can occur in three different ways: (a) de-novo occurrence, (b) recurrence of malignancy, and (c) donor-related malignancy. Donor related malignancy can be either due to direct transmission of tumor or due to tumor arising in cells of donor origin. We will review donor related malignancies following solid organ transplantation and hematopoeitic progenitor cell transplantation. Further, we will briefly review the methods for detection and management of these donor related malignancies.     

Green fluorescent protein-transgenic rat: a tool for organ transplantation research

The purpose of this study is to evaluate green fluorescent protein (GFP) transgenic rats for use as a tool for organ transplantation research. The GFP gene construct was designed to express ubiquitously. By flow cytometry, the cells obtained from the bone marrow, spleen, and peripheral blood of the GFP transgenic rats consisted of 77, 91, and 75% GFP-positive cells, respectively. To examine cell migration of GFP-positive cells after organ transplantation, pancreas graft with or without spleen transplantation, heart graft with or without lung transplantation, auxiliary liver and small bowel transplantation were also performed from GFP transgenic rat to LEW (RT1(1)) rats under a 2-week course of 0.64 mg/kg tacrolimus administration. GFP-positive donor cells were detected in the fully allogenic LEW rats after organ transplantation. These results showed that GFP transgenic rat is a useful tool for organ transplantation research such as cell migration study after organ transplantation without donor cell staining.     

Will more organs save more lives? Cost‐effectiveness and the ethics of expanding organ procurement

The assumption that procuring more organs will save more lives has inspired increasingly forceful calls to increase organ procurement. This project, in contrast, directly questions the premise that more organ transplantation means more lives saved. Its argument begins with the fact that resources are limited and medical procedures have opportunity costs. Because many other lifesaving interventions are more cost‐effective than transplantation and compete with transplantation for a limited budget, spending on organ transplantation consumes resources that could have been used to save a greater number of other lives. This argument has not yet been advanced in debates over expanded procurement and could buttress existing concerns about expanded procurement. To support this argument, I review existing empirical data on the cost‐effectiveness of transplantation and compare them to data on interventions for other illnesses. These data should motivate utilitarians and others whose primary goal is maximizing population‐wide health benefits to doubt the merits of expanding organ procurement. I then consider two major objections: one makes the case that transplant candidates have a special claim to medical resources, and the other challenges the use of cost‐effectiveness to set priorities. I argue that there is no reason to conclude that transplant candidates’ medical interests should receive special priority, and that giving some consideration to cost‐effectiveness in priority setting requires neither sweeping changes to overall health priorities nor the adoption of any specific, controversial metric for assessing cost‐effectiveness. Before searching for more organs, we should first ensure the provision of cost‐effective care.     

IL-12 gene therapy is an effective therapeutic strategy for hepatocellular carcinoma in immunosuppressed mice

Immunosuppressive therapy for organ transplantation is essential for controlling rejection. When liver transplantation is performed as a therapy for hepatocellular carcinoma (HCC), recurrent HCC is one of the most fatal complications. In this study, we show that intratumoral murine IL-12 (mIL-12) gene therapy has the potential to be an effective treatment for malignancies under immunosuppression. C3H mice (H-2(k)), injected with FK506 (3 mg/kg) i.p., were s.c. implanted with 2.5 x 10(6) MH134 cells (H-2(k)) and we treated the established HCC with electroporation-mediated gene therapy using mIL-12 plasmid DNA. Intratumoral gene transfer of mIL-12 elevated intratumoral mIL-12, IFN-gamma, and IFN-gamma-inducible protein-10, significantly reduced the number of microvessels and inhibited the growth of HCC, compared with HCC-transferred control pCAGGS plasmid. The inhibition of tumor growth in immunosuppressed mice was comparable with that of mIL-12 gene therapy in immunocompetent mice. Intratumoral mIL-12 gene therapy enhanced lymphocytic infiltration into the tumor and elicited the MH134-specific CTL response even under FK506. The dose of FK506 was sufficient to prevent the rejection of distant allogenic skin grafts (BALB/c mice, H-2(d)) and tumors, B7-p815 (H-2(d)) used as transplants, during mIL-12 gene therapy against MH134. Ab-mediated depletion studies suggested that the inhibition of tumor growth, neovascularization, and spontaneous lung metastasis by mIL-12 was dependent almost entirely on NK cells and partially on T cells. These results suggest that intratumoral mIL-12 gene therapy is a potent effective strategy not only to treat recurrences of HCC in liver transplantation, but also to treat solid malignant tumors in immunosuppressed patients with transplanted organ.     

The trade in human liver lobes: bioviolence against organ sellers in Bangladesh

The rapid growth in organ transplantation has created an illicit trade in human organs. The kidney trade has flourished in the last few decades, but in the last few years this has been coupled with an emerging liver trade. This article examines the liver trade sourced from poor sellers in Bangladesh. Through ethnographic fieldwork, I investigate how a landless farmer and a village housewife both sell their liver lobes on the black market, and how the recipients undergo liver transplants in Bangladesh and India. I reveal that liver selling, like kidney selling, is primarily driven by the sellers’ debt. What is surprising, though, in this anthropological analysis is that microcredit, a Nobel Prize-winning economic operation, has negatively contributed to organ selling in Bangladesh. I discover that the liver trade leads to tragic outcomes for both sellers and recipients: the sellers could not repay their loans by selling a liver lobe, while one of the recipients died just over a month after the surgery. I therefore argue that liver trade is advancing through a series of disturbing ironies, resulting in bioviolence, exploitation, and suffering for the vulnerable victims.     

Artificial and Bioartificial Liver Support

The liver is a complex organ with various vital functions in synthesis, detoxification and regulation; its failure therefore constitutes a life threatening condition1. Liver failure (LF) can either occur without preceding liver disease (acute liver failure, ALF), usually caused either by intoxication (Amanita phalloides, acetaminophen, methylendioxymethamphteamine) or as acute decompensation of chronic liver-related illness (acute-on-chronic liver failure, AoCLF). In both cases, its symptoms include icterus, hepatic encephalopathy and impairment of coagulation status and may result in multi organ failure. Exceptionally, liver failure may also be triggered by certain diseases (Budd-Chiari-syndrome, Morbus Wilson) or pregnancy. The only long-term therapy in most cases is orthotopic liver transplantation, unless the liver is able to regenerate. Many patients, especially those who are not listed for high urgency transplantation, may not survive until a suitable donor organ is available, since donor organs are rare. In other cases, contraindications do not permit liver transplantation. For these indications, extracorporeal liver assist devices have been developed in order to either bridge the patient to transplantation or temporarily support the failing organ until it is able to regenerate.     

Gene therapy strategies to facilitate organ transplantation.

Organ transplantation is now the definitive therapy for many forms of end-organ disease, but chronic allograft rejection, the side effects of chronic immunosuppressive therapy and the severe donor organ shortage continue to limit its success. Gene therapy has the potential to prevent graft rejection by manipulating the immune response in the microenvironment of the graft or by facilitating the induction of tolerance. Genetic manipulation of stem cells to create transgenic and/or knockout animals that could serve as organ or cell donors could be combined with gene therapy approaches to overcome the problem of limited allogeneic donor organ supply.     

Oncolytic viral purging of leukemic hematopoietic stem and progenitor cells with Myxoma virus

High-dose chemotherapy and radiation followed by autologous blood and marrow transplantation (ABMT) has been used for the treatment of certain cancers that are refractory to standard therapeutic regimes. However, a major challenge with ABMT for patients with hematologic malignancies is disease relapse, mainly due to either contamination with cancerous hematopoietic stem and progenitor cells (HSPCs) within the autograft or the persistence of residual therapy-resistant disease niches within the patient. Oncolytic viruses represent a promising therapeutic approach to prevent cancer relapse by eliminating tumor-initiating cells that contaminate the autograft. Here we summarize an ex vivo “purging” strategy with oncolytic Myxoma virus (MYXV) to remove cancer-initiating cells from patient autografts prior to transplantation. MYXV, a novel oncolytic poxvirus with potent anti-cancer properties in a variety of in vivo tumor models, can specifically eliminate cancerous stem and progenitor cells from samples obtained from acute myelogenous leukemia (AML) patients, while sparing normal CD34+ hematopoietic stem and progenitor cells capable of rescuing hematopoiesis following high dose conditioning. We propose that a broader subset of patients with intractable hematologic malignancies who have failed standard therapy could become eligible for ABMT when the treatment schema is coupled with ex vivo oncolytic therapy.     

Association between IL-4 polymorphism and acute rejection of solid organ allograft: A meta-analysis

Background

Cytokines have been implicated in the acute rejection of solid organ transplantation. Many studies have investigated the association between recipient or donor IL-4 polymorphism and acute rejection, with different studies reporting inconclusive results.

Methods

We searched PUBMED and EMBASE until June 2012 to identify eligible studies investigating the association between IL-4 polymorphism with acute rejection after solid organ transplantation. Statistical analysis was performed using STATA10.0.

Results

A total of 12 studies were included. Pooled ORs suggested 1) no significant association was detected between recipient or donor IL-4 − 590C/T polymorphism and acute rejection of solid allograft; 2) no significant association was detected between recipient IL-4 − 33C/T polymorphism and acute rejection of solid allograft; 3) when stratified by transplantation type, IL-4 − 590C/T polymorphism was associated with acute rejection of liver transplantation (T/T + C/T vs. C/C: OR = 0.36, 95%CI = 0.14–0.90); 4) significantly decreased risk of acute rejection was detected in recipient IL-4 − 590*T-negative/donor T-positive genotype pairs than all other recipient–donor IL-4 − 590T/C pairs (OR = 0.14, 95%CI = 0.03–0.66).

Conclusions

Our meta-analysis suggested that recipient IL-4 − 590C/T polymorphism was associated with acute rejection of liver transplantation, but nor renal or heart transplantation. It was also suggested that combined recipient IL-4 − 590*T-negative/donor T-positive genotype may suffer decreased risk of acute rejection of solid allograft. Further well-designed studies with larger sample size were required to verify our findings, with focus on the association of IL-4 polymorphism with acute rejection in patients with liver transplantation and studies investigating combined recipient–donor genotype.     

From hepatocytes to stem and progenitor cells for liver regenerative medicine: advances and clinical perspectives

The parenchymal liver cell is a unique fully functional metabolic unit that can be used for liver regenerative medicine to restore function of the diseased organ; the aim of the procedure is to prevent progression of end-stage disease. The alternative, orthotopic liver transplantation, is highly intrusive, irreversible and limited by general organ shortage. Mature liver cell - hepatocyte - transplantation has been shown to have short- to medium-term efficacy for correction of miscellaneous inborn errors of metabolism. However, although proof of concept has been established, the procedure has not yet achieved full success, due to limited durability of functional benefit. Hepatocyte procurement is also restricted by organ shortage, and their storage is difficult due to poor tolerance of cryopreservation. Alternative cell sources are therefore needed for development and wider accessibility of cell-based liver regenerative medicine. Besides safety, the main challenge for these alternative cells is to acquire similar levels of functionality once implanted into the target organ. In this respect, liver derived progenitor cells may have some advantages over stem cells derived from other tissues.     

肝脏类器官的研究及应用进展

肝脏疾病易感性差异大且个体间的肝脏细胞存在明显的异质性,因此开发体外能够长期存活并具有代谢功能的人体类肝组织细胞模型,对治疗终末期肝病、开展肝脏致病机理研究及药物筛选具有重要意义。过去十年中,体外三维类器官模型发展迅猛,为疾病模拟、精准化治疗领域的研究提供了新的工具,显示出巨大潜力。肝脏类器官具有患者的基因表达与突变特征,在体外能够较长时间地保持肝脏细胞功能,已被应用于疾病模拟及药物有效性研究,并具有进行原位或异位移植发挥治疗作用的应用潜能。就干细胞、肝脏原代细胞等不同来源的肝脏类器官的发展及近年的研究进展作了综述,以期为肝脏类器官在疾病建模、药物发现和器官移植领域的研究和应用提供新的思路。     

Hepatic progenitor cells

Liver diseases are associated with a marked reduction in the viable mass of hepatocytes. The most severe cases of liver disease (liver failure) are treated by orthotopic liver transplantation. One alternative to whole organ transplantation for patients with hepatic failure (and hereditary liver disease) is hepatocyte transplantation. However, there is a serious limitation to the treatment of liver diseases either by whole organ or hepatocyte transplantation, and that is the shortage of organ donors. Therefore, to overcome the problem of organ shortage, additional sources of hepatocytes must be found. Alternative sources of cells for transplantation have been proposed including embryonic stem cells, immortalised liver cells and differentiated cells. One other source of cells for transplantation found in the adult liver is the progeny of stem cells. These cells are termed hepatic progenitor cells (HPCs). The therapeutic potential of HPCs lies in their ability to proliferate and differentiate into hepatocytes and cholangiocytes. However, using HPCs as a cell therapy cannot be exploited fully until the mechanisms governing hepatocyte differentiation are elucidated. Here, we discuss the fundamental cellular and molecular elements required for HPC differentiation to hepatocytes.     

Strategies for organ level tissue engineering

The field of tissue engineering has made considerable strides since it was first described in the late 1980s. The advent and subsequent boom in stem cell biology, emergence of novel technologies for biomaterial development, and further understanding of developmental biology have contributed to this accelerated progress. However, continued efforts to translate tissue engineering strategies into clinical therapies have been hampered by the problems associated with scaling up laboratory methods to produce large, complex tissues. The significant challenges faced by tissue engineers include the production of an intact vasculature within a tissue-engineered construct and recapitulation of the size and complexity of a whole organ. Here we review the basic components necessary for bioengineering organs – biomaterials, cells and bioactive molecules–and discuss various approaches for augmenting these principles to achieve organ level tissue engineering. Ultimately, the successful translation of tissue-engineered constructs into everyday clinical practice will depend upon the ability of the tissue engineer to “scale up” every aspect of the research and development process.