Differentiation and transplantation of human embryonic stem cell-derived hepatocytes

BACKGROUND & AIMS

The ability to obtain unlimited numbers of human hepatocytes would improve the development of cell-based therapies for liver diseases, facilitate the study of liver biology, and improve the early stages of drug discovery. Embryonic stem cells are pluripotent, potentially can differentiate into any cell type, and therefore could be developed as a source of human hepatocytes.

METHODS

To generate human hepatocytes, human embryonic stem cells were differentiated by sequential culture in fibroblast growth factor 2 and human activin-A, hepatocyte growth factor, and dexamethasone. Functional hepatocytes were isolated by sorting for surface asialoglycoprotein-receptor expression. Characterization was performed by real-time polymerase chain reaction, immunohistochemistry, immunoblot, functional assays, and transplantation.

RESULTS

Embryonic stem cell-derived hepatocytes expressed liver-specific genes, but not genes representing other lineages, secreted functional human liver-specific proteins similar to those of primary human hepatocytes, and showed human hepatocyte cytochrome P450 metabolic activity. Serum from rodents given injections of embryonic stem cell-derived hepatocytes contained significant amounts of human albumin and alpha1-antitrypsin. Colonies of cytokeratin-18 and human albumin-expressing cells were present in the livers of recipient animals.

CONCLUSIONS

Human embryonic stem cells can be differentiated into cells with many characteristics of primary human hepatocytes. Hepatocyte-like cells can be enriched and recovered based on asialoglycoprotein-receptor expression and potentially could be used in drug discovery research and developed as therapeutics.

Reversal of mouse hepatic failure using an implanted liver-assist device containing ES cell-derived hepatocytes

Severe acute liver failure, even when transient, must be treated by transplantation and lifelong immune suppression. Treatment could be improved by bioartificial liver (BAL) support, but this approach is hindered by a shortage of human hepatocytes. To generate an alternative source of cells for BAL support, we differentiated mouse embryonic stem (ES) cells into hepatocytes by coculture with a combination of human liver nonparenchymal cell lines and fibroblast growth factor-2, human activin-A and hepatocyte growth factor. Functional hepatocytes were isolated using albumin promoter-based cell sorting. ES cell-derived hepatocytes expressed liver-specific genes, secreted albumin and metabolized ammonia, lidocaine and diazepam. Treatment of 90% hepatectomized mice with a subcutaneously implanted BAL seeded with ES cell-derived hepatocytes or primary hepatocytes improved liver function and prolonged survival, whereas treatment with a BAL seeded with control cells did not. After functioning in the BAL, ES cell-derived hepatocytes developed characteristics nearly identical to those of primary hepatocytes.

Reactive bone marrow stromal cells attenuate systemic inflammation via sTNFR1

Excessive systemic inflammation following trauma, sepsis, or burn could lead to distant organ damage. The transplantation of bone marrow stromal cells or mesenchymal stem cells (MSCs) has been reported to be an effective treatment for several immune disorders by modulating the inflammatory response to injury. We hypothesized that MSCs can dynamically secrete systemic factors that can neutralize the activity of inflammatory cytokines. In this study, we showed that cocultured MSCs are able to decrease nuclear factor κ-B (NFκB) activation in target epithelial cells incubated in inflammatory serum conditions. Proteomic screening revealed a responsive secretion of soluble tumor necrosis factor (TNF) receptor 1 (sTNFR1) when MSCs were exposed to lipopolysaccharide (LPS)-stimulated rat serum. The responsive effect was eliminated when NFκB activation was blocked in MSCs. Intramuscular transplantation of MSCs in LPS-endotoxic rats decreased a panel of inflammatory cytokines and inflammatory infiltration of macrophages and neutrophils in lung, kidney, and liver when compared to controls. These results suggest that improvements of inflammatory responses in animal models after local transplantation of MSCs are at least, in part, explained by the NFκB-dependent secretion of sTNFR1 by MSCs.

Differentiation of mouse embryonic stem cells to hepatocyte-like cells by co-culture with human liver nonparenchymal cell lines

This protocol describes a co-culture system for the in vitro differentiation of mouse embryonic stem cells into hepatocyte-like cells. Differentiation involves four steps: (i) formation of embryoid bodies (EB), (ii) induction of definitive endoderm from 2-d-old EBs, (iii) induction of hepatic progenitor cells and (iv) maturation into hepatocyte-like cells. Differentiation is completed by 16 d of culture. EBs are formed, and cells can be induced to differentiate into definitive endoderm by culture in Activin A and fibroblast growth factor 2 (FGF-2). Hepatic differentiation and maturation of cells is accomplished by withdrawal of Activin A and FGF-2 and by exposure to liver nonparenchymal cell-derived growth factors, a deleted variant of hepatocyte growth factor (dHGF) and dexamethasone. Approximately 70% of differentiated embryonic stem (ES) cells express albumin and can be recovered by albumin promoter-based cell sorting. The sorted cells produce albumin in culture and metabolize ammonia, lidocaine and diazepam at approximately two-thirds the rate of primary mouse hepatocytes.

A human beta-cell line for transplantation therapy to control type 1 diabetes

A human pancreatic beta-cell line that is functionally equivalent to primary beta-cells has not been available. We established a reversibly immortalized human beta-cell clone (NAKT-15) by transfection of primary human beta-cells with a retroviral vector containing simian virus 40 large T-antigen (SV40T) and human telomerase reverse transcriptase (hTERT) cDNAs flanked by paired loxP recombination targets, which allow deletion of SV40T and TERT by Cre recombinase. Reverted NAKT-15 cells expressed beta-cell transcription factors (Isl-1, Pax 6, Nkx 6.1, Pdx-1), prohormone convertases 1/3 and 2, and secretory granule proteins, and secreted insulin in response to glucose, similar to normal human islets. Transplantation of NAKT-15 cells into streptozotocin-induced diabetic severe combined immunodeficiency mice resulted in perfect control of blood glucose within 2 weeks; mice remained normoglycemic for longer than 30 weeks. The establishment of this cell line is one step toward a potential cure of diabetes by transplantation.

Prolonged Survival Following Pig-to-Primate Liver Xenotransplantation Utilizing Exogenous Coagulation Factors and Costimulation Blockade

Since the first attempt of pig-to-primate liver xenotransplantation (LXT) in 1968, survival has been limited. We evaluated a model utilizing α-1,3-galactosyltransferase knockout donors, continuous posttransplant infusion of human prothrombin concentrate complex, and immunosuppression including anti-thymocyte globulin, FK-506, methylprednisone, and costimulation blockade (belatacept, n = 3 or anti-CD40 mAb, n = 1) to extend survival. Baboon 1 remained well until postoperative day (POD) 25, when euthanasia was required because of cholestasis and plantar ulcers. Baboon 2 was euthanized following a seizure on POD 5, despite normal liver function tests (LFTs) and no apparent pathology. Baboon 3 demonstrated initial stable liver function but was euthanized on POD 8 because of worsening LFTs. Pathology revealed C4d positivity, extensive hemorrhagic necrosis, and a focal cytomegalovirus inclusion. Baboon 4 was clinically well with stable LFTs until POD29, when euthanasia was again necessitated by plantar ulcerations and rising LFTs. Final pathology was C4d negative and without evidence of rejection, inflammation, or thrombotic microangiopathy. Thus, nearly 1-mo rejection-free survival has been achieved following LXT in two of four consecutive recipients, demonstrating that the porcine liver can support life in primates for several weeks and has encouraging potential for clinical application as a bridge to allotransplantation for patients with acute-on-chronic or fulminant hepatic failure.

PuraMatrix facilitates bone regeneration in bone defects of calvaria in mice

Artificial bones have often used for bone regeneration due to their strength, but they cannot provide an adequate environment for cell penetration and settlement. We therefore attempted to explore various materials that may allow the cells to penetrate and engraft in bone defects. PuraMatrix is a self-assembling peptide scaffold that produces a nanoscale environment allowing both cellular penetration and engraftment. The objective of this study was to investigate the effect of PuraMatrix on bone regeneration in a mouse bone defect model of the calvaria. Matrigel was used as a control. The expression of bone-related genes (alkaline phosphatase, Runx2, and Osterix) in the PuraMatrix-injected bone defects was stronger than that in the Matrigel-injected defects. Soft X-ray radiographs revealed that bony bridges were clearly observed in the defects treated with PuraMatrix, but not in the Matrigel-treated defects. Notably, PuraMatrix treatment induced mature bone tissue while showing cortical bone medullary cavities. The area of newly formed bones at the site of the bone defects was 1.38-fold larger for PuraMatrix than Matrigel. The strength of the regenerated bone was 1.72-fold higher for PuraMatrix (146.0 g) than for Matrigel (84.7 g). The present study demonstrated that PuraMatrix injection favorably induced functional bone regeneration.

Combination of exosomes and circulating microRNAs may serve as a promising tumor marker complementary to alpha-fetoprotein for early-stage hepatocellular carcinoma diagnosis in rats

PURPOSE

Due to unsatisfying prognosis of AFP for hepatocellular carcinoma (HCC), we aim to evaluate the prognostic value of combination of exosomes and miRNAs in detecting HCC.

METHODS

HCC was induced with diethylnitrosamine in rats and using a scoring system based on histological examination six different stages (normal liver, degeneration, fibrosis, cirrhosis, early HCC and late HCC) were identified in the development of HCC. The expression levels of AFP, exosomes and miRNAs (miRNA-10b, miRNA-21, miRNA-122 and miRNA-200a) were detected in both tissue and blood samples from those six stages. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the power of each parameter and their different combinations in diagnosing HCC or cirrhosis.

RESULTS

A change in the expression of both exosomes and miRNAs was observed during cirrhosis, which in contrast with AFP starts showing up until the early HCC stage. Interestingly, the expressions of exosomes and the selected four miRNAs at early HCC stage obtained more remarkably alterations than the level of AFP (P < 0.05). On correlation analysis, four selected miRNAs had a significant closer relationship with exosomes when compared with AFP. The different combinations of AFP, exosomes, serous miRNAs and exosomal miRNAs had stronger power in predicting HCC than AFP (area under the curve of ROC, 0.943 vs 0.826).

CONCLUSION

To conclude, the combination of circulating miRNAs and exosomes might serve as promising biomarkers for non-virus infected HCC screening and cirrhosis discrimination.

Cell delivery: from cell transplantation to organ engineering

Cell populations derived from adult tissue and stem cells possess a great expectation for the treatment of several diseases. Great efforts have been made to generate cells with therapeutic impact from stem cells. However, it is clear that the development of systems to deliver such cells to induce efficient engraftment, growth, and function is a real necessity. Biologic and artificial scaffolds have received significant attention for their potential therapeutic application when use to form tissues in vitro and facilitate engraftment in vivo. Ultimately more sophisticated methods for decellularization of organs have been successfully used in tissue engineering and regenerative medicine applications. These decellularized tissues and organs appear to provide bioactive molecules and bioinductive properties to induce homing, differentiation, and proliferation of cells. The combination of decellularized organs and stem cells may dramatically improve the survival, engraftment, and fate control of transplanted stem cells and their ultimate clinical utility, opening the doors to a new era of organ engineering.

Reestablishment of microenvironment is necessary to maintain in vitro and in vivo human islet function

Islet transplantation is associated with an elevated rate of early graft failure. The isolation process leads to structural and functional abnormalities. The reestablishment of the cell-matrix relationship is important to modulate the survival and function of islets. Thus, we evaluated the effect of human fibronectin (hFN) and self-assembling peptide nanofiber (SAPNF) in the ability to support islet function in vitro and after transplantation into streptozotocin (STZ)-induced diabetic severe combined immunodeficiency (SCID) mice. Human isolated islets were cultured with hFN or SAPNF for 7 days. Their ability to maintain insulin production/glucose responsiveness over time was evaluated. Islets embedded in hFN, SAPNF, or alone were transplanted into STZ-induced diabetic SCID mice. Islet grafts were removed after 14 days to evaluate insulin content, insulin expression, and apoptosis. SAPNF-entrapped islets maintained satisfactory morphology/viability and capability of glucose-dependent insulin secretion for over 7 days, whereas islets cultured in hFN underwent widespread deterioration. In vivo grafts containing human islets in SAPNF showed remarkably higher insulin content and expression when compared with human islets in hFn or alone. RT-PCR revealed lower caspase-3 expression in SAPNF islets grafts. These studies indicate that the reestablishment of the cell-matrix interactions by a synthetic matrix in the immediate postisolation period is a useful tool to maintain islet functions in vitro and in vivo.

CD47: a new player in phagocytosis and xenograft rejection

Organ transplantation is limited by the availability of human donor organs. The transplantation of organs and tissues from other species (xenotransplantation) would supply an unlimited number of organs and offer many other advantages for which the pig has been identified as the most suitable source. However, the robust immune responses to xenografts remain a major obstacle to clinical application of xenotransplantation. The more vigorous xenograft rejection relative to allograft rejection is largely accounted for by the extensive genetic disparities between the donor and recipient. Xenografts activate host immunity not only by expressing immunogenic xenoantigens that provide the targets for immune recognition and rejection, but also by lacking ligands for the host immune inhibitory receptors. This review is focused on recent findings regarding the role of CD47, a ligand of an immune inhibitory receptor, signal regulatory protein alpha (SIRPα), in phagocytosis and xenograft rejection.

Galectin-3 as a potential prognostic biomarker of severe COVID-19 in SARS-CoV-2 infected patients

Severe COVID-19 is associated with a systemic hyperinflammatory response leading to acute respiratory distress syndrome (ARDS), multi-organ failure, and death. Galectin-3 is a ß-galactoside binding lectin known to drive neutrophil infiltration and the release of pro-inflammatory cytokines contributing to airway inflammation. Thus, we aimed to investigate the potential of galectin-3 as a biomarker of severe COVID-19 outcomes. We prospectively included 156 patients with RT-PCR confirmed COVID-19. A severe outcome was defined as the requirement of invasive mechanical ventilation (IMV) and/or in-hospital death. A non-severe outcome was defined as discharge without IMV requirement. We used receiver operating characteristic (ROC) and multivariable logistic regression analysis to determine the prognostic ability of serum galectin-3 for a severe outcome. Galectin-3 levels discriminated well between severe and non-severe outcomes and correlated with markers of COVID-19 severity, (CRP, NLR, D-dimer, and neutrophil count). Using a forward-stepwise logistic regression analysis we identified galectin-3 [odds ratio (OR) 3.68 (95% CI 1.47-9.20), p < 0.01] to be an independent predictor of severe outcome. Furthermore, galectin-3 in combination with CRP, albumin and CT pulmonary affection > 50%, had significantly improved ability to predict severe outcomes [AUC 0.85 (95% CI 0.79-0.91, p < 0.0001)]. Based on the evidence presented here, we recommend clinicians measure galectin-3 levels upon admission to facilitate allocation of appropriate resources in a timely manner to COVID-19 patients at highest risk of severe outcome.

Gene delivery to embryonic stem cells

Since the establishment of embryonic stem (ES) cells and the identification of tissue-specific stem cells, researchers have made great strides in the analysis of the natural biology of such stem cells for the development of therapeutic applications. Specifically, ES cells are capable of differentiating into all of the cell types that constitute the whole body. Thus, ES cell research promises new type of treatments and possible cures for a variety of debilitating diseases and injuries. The potential medical benefits obtained from stem cell technology are compelling and stem cell research sees a bright future. Control of the growth and differentiation of stem cells is a critical tool in the fields of regenerative medicine, tissue engineering, drug discovery, and toxicity testing. Toward such a goal, we present here an overview of gene delivery in ES cells, covering the following topics: significance of gene delivery in ES cells, stable versus transient gene delivery, cytotoxicity, suspension versus adherent cells, expertise, time, cost, viral vectors for gene transduction (lentiviruses, adenoviruses, and adeno-associated viruses, chemical methods for gene delivery, and mechanical or physical gene delivery methods (electroporation, nucleofection, microinjection, and nuclear transfer).

Differentiation of human embryonic stem cells to hepatocytes using deleted variant of HGF and poly-amino-urethane-coated nonwoven polytetrafluoroethylene fabric

Human embryonic stem (hES) cells have recently been studied as an attractive source for the development of a bioartificial liver (BAL). Here we evaluate the differentiation capacity of hES cells into hepatocytes. hES cells were subjected to suspension culture for 5 days, and then cultured onto poly-amino-urethane (PAU)-coated, nonwoven polytetrafluoroethylene (PTFE) fabric in the presence of fibroblast growth factor-2 (bFGF) (100 ng/ml) for 3 days, then with deleted variant of hepatocyte growth factor (dHGF) (100 ng/ml) and 1% dimethyl sulfoxide (DMSO) for 8 days, and finally with dexamethasone (10(-7) M) for 3 days. The hES cells showed gene expression of albumin in a time-dependent manner of the hepatic differentiation process. The resultant hES-derived hepatocytes metabolized the loaded ammonia and lidocaine at 7.8% and 23.6%, respectively. A million of such hepatocytes produced albumin and urea at 351.2 ng and urea at 7.0 microg. Scanning electron microscopy showed good attachment of the cells on the surface of the PTFE fabric and well-developed glycogen rosettes and Gap junction. In the present work we have demonstrated the efficient differentiation of hES cells to functional hepatocytes. The findings are useful to develop a BAL.

Engineering of an hepatic organoid to develop liver assist devices

Cell-based technologies to support/restore liver function represent one of the most promising opportunities in the treatment of acute liver failure. However, the understanding of the constituent cell types that interact to achieve liver-specific structure and function has not been achieved in the development of liver assist devices (LADs). Here we show that hepatocytes migrated toward and adhered and formed sinusoids-like structures in conjunction with liver nonparenchymal cells, and that this liver organoid formed sophisticated tissue after 7 days in an implanted LAD in rodents. Hepatocytes only or in combination with human nonparenchymal liver cell lines (endothelial, cholangiocytes, and stellate cells) were cultured in Matrigel. Ultrastructural analysis showed that the hepatocyte-decorated endothelial vascular structures resemble in vivo sinusoids containing plate-like structures, bile canaliculi, and lumen. The sinusoid-like structures retained albumin secretion and drug metabolism capabilities. In addition, LADs containing cocultures of human liver nonparenchymal cells were transplanted in animals for a week; the liver tissue formed sophisticated structures resembling the liver. These results demonstrate the importance of nonparenchymal cells in the cellular composition of LADs. The novelty of the culture's sinusoid-like organization and function strongly support the integration of liver nonparenchymal units into hepatocyte coculture-based LADs as a potential destination therapy for liver failure.

Survival of liver failure pigs by transplantation of reversibly immortalized human hepatocytes with Tamoxifen-mediated self-recombination

BACKGROUND/AIMS

Hepatocyte transplantation and bioartificial liver treatment are attractive alternatives to liver transplantation. The availability of well-characterized human hepatocyte lines facilitates such cell therapies.

METHODS

Human hepatocytes were immortalized with a retroviral vector SSR#197 expressing catalytic subunit of human telomerase reverse transcriptase (hTERT) and enhanced green fluorescent protein (EGFP) cDNAs flanked by a pair of loxP recombination targets. Then, Tamoxifen-dependent Cre recombinase was expressed in SSR#197-immortalized hepatocytes. Cre/LoxP recombination was performed in the established cells by simple exposure to 500 nM Tamoxifen for a week. Then, the reverted population of the cells was recovered by EGFP-negative cell sorting and characterized in vitro and in vivo using a pig model of acute liver failure (ALF) induced by d-galactosamine (0.5 g/kg) injection.

RESULTS

A human hepatocyte cell line 16T-3 was established. Reverted 16-T3 cells showed the increased expression of hepatic markers in association with enhanced levels of transcriptional factors. Compared to normal human hepatocytes, albumin production and lidocaine-metabolizing activities of reverted 16-T3 cells were 0.32 and 0.50-fold, respectively. Transplantation of reverted 16T-3 cells significantly prolonged the survival of ALF pigs.

CONCLUSIONS

Here we demonstrate the usefulness of Cre/LoxP -mediated reversible immortalization of human hepatocytes with Tamoxifen-mediated self-recombination.

Self-assembling peptide nanofiber as a novel culture system for isolated porcine hepatocytes

Freshly isolated porcine hepatocytes are a very attractive cell source in the cell-based therapies to treat liver failure because of unlimited availability. However, due to the loss of hepatocyte functions in vitro, there is a need to develop a functional culture system to keep the cells metabolically active. Here we compared the effect of a self-assembling peptide nanofiber (SAPNF) as an extracellular matrix (ECM) with collagen type I on hepatocyte metabolic and secretion activities following hepatocyte isolation. Isolated porcine hepatocytes were cultured in SAPNF and collagen type I. Morphological assessment at different time points was performed by using SEM and phase contrast microscope. Metabolic and secretion activities were comparatively performed in the groups, by means of ammonia, lidocaine, and diazepam as well as albumin. Hepatocytes cultured on SAPNF revealed a three-dimensional spheroidal formation, thus maintaining cell differentiation status during 2 weeks of culture. On the other hand, hepatocytes in collagen revealed a spread shape, and by day 14 no hepatocyte-like cells were observed, but cells with long shape were present, thus revealing a degree of dedifferentiation in collagen culture. Hepatocytes in SAPNF were capable of drug-metabolizing activities and albumin secretion in higher ratio than those cultured on collagen. The present work clearly demonstrates the usefulness of SAPNF for maintaining differentiated functions of porcine hepatocytes in culture.

Instant hepatic differentiation of human embryonic stem cells using activin A and a deleted variant of HGF

Human embryonic stem (hES) cells have the ability to differentiate into a variety of different cell lineages and potentially provide a source of differentiated cells for many therapeutic uses. Here we investigated an efficient method of hepatic differentiation from hES cells. A human ES cell line, KhES-1, was used and maintained by a nonfeeder method. KhES-1 cells were cultured for 5 days in the presence of human activin A (50 ng/ml) and then treated with a deleted variant of hepatocyte growth factor (dHGF) at 0, 100, or 500 ng/ml for 7 days. The resultant cells were biologically analyzed. The expression of the endodermal genes SOX17 and FOXA2 increased in KhES-1 cells after activin A treatment. In contrast, Oct4, a self-renewal undifferentiated marker, decreased in a time-dependent manner in KhES-1 cells. Following a 7-day treatment of the resultant cells with dHGF, especially at 500 ng/ml, KhES-1 cells showed an expression of the hepatic makers albumin, AFP, and CK18. Transitional electron microscopy showed well-developed glycogen rosettes and a gap junction in KhES-1 cells treated with 500 ng/ml of dHGF. We developed an efficient method to differentiate KhES-1 cells into hepatocyte-like cells in vitro using 50 ng/ml of activin A and 500 ng/ml of dHGF.

The Effects of Exogenous Administration of Human Coagulation Factors Following Pig-to-Baboon Liver Xenotransplantation

We sought to determine the effects of exogenous administration of human coagulation factors following pig-to-baboon liver xenotransplantation (LXT) using GalT-KO swine donors. After LXT, baboons received no coagulation factors (historical control, n = 1), bolus administration of a human prothrombin concentrate complex (hPCC; 2.5 mL/kg, n = 2), continuous infusion of hPCC (1.0 mL/h, n = 1) or continuous infusion of human recombinant factor VIIa (1 µg/kg per hour, n = 3). The historical control recipient demonstrated persistent thrombocytopenia despite platelet administration after transplant, along with widespread thrombotic microangiopathy (TMA). In contrast, platelet levels were maintained in bolus hPCC recipients; however, these animals quickly developed large-vessel thrombosis and TMA, leading to graft failure with shortened survival. Recipients of continuous coagulation factor administration experienced either stabilization or an increase in their circulating platelets with escalating doses. Furthermore, transfusion requirements were decreased, and hepatic TMA was noticeably absent in recipients of continuous coagulation factor infusions compared with the historical control and bolus hPCC recipients. This effect was most profound with a continuous, escalating dose of factor VIIa. Further studies are warranted because this regimen may allow for prolonged survival following LXT.

Maintenance of mouse, rat, and pig pancreatic islet functions by coculture with human islet-derived fibroblasts

Development of an efficient preculture system of islets is ideal. Toward that goal, we constructed a human pancreatic islet-derived fibroblast cell line MNNK-1 for a source as a coculture system for freshly isolated islets to maintain islet functions. Human pancreatic islet cells were nucleofected with a plasmid vector pYK-1 expressing simian virus 40 large T antigen gene (SV40T) and hygromycin resistance gene (HygroR). One of the transduced cell lines, MNNK-1, was established and served as a feeder cell in the coculture for freshly isolated mouse, rat, and pig islets. Morphology, viability, and glucose-responding insulin secretion were analyzed in the coculture system. MNNK-1 cells were morphologically spindle shaped and were negative for pancreatic endocrine markers. MNNK-1 cells were positive for alpha-smooth muscle actin and collagen type I and produced fibroblast growth factor. Coculture of the mouse, rat, and pig islets with MNNK-1 cells maintained their viability and insulin secretion with glucose responsiveness. A human pancreatic islet-derived fibroblast cell line MNNK-1 was established. MNNK-1 cells were a useful means for maintaining morphology and insulin secretion of islets in the coculture system.

Intramuscular transplantation of engineered hepatic tissue constructs corrects acute and chronic liver failure in mice

BACKGROUND & AIMS

Transplantation of isolated hepatocytes holds great promise as an alternative to whole organ liver transplantation. For treatment of liver failure, access to the portal circulation has significant risks and intrahepatic hepatocyte engraftment is poor. In advanced cirrhosis, transplantation into an extrahepatic site is necessary and intrasplenic engraftment is short-lived. Strategies that allow repeated extrahepatic infusion of hepatocytes could improve the efficacy and safety of hepatocyte transplantation for the treatment of liver failure.

METHODS

A non-immunogenic self-assembling peptide nanofiber (SAPNF) was developed as a three-dimensional scaffold and combined with growth factors derived from a conditionally immortalized human hepatocyte cell line to engineer a hepatic tissue graft that would allow hepatocyte engraftment outside the liver.

RESULTS

The hepatic tissue constructs maintained hepatocyte-specific gene expression and functionality in vitro. When transplanted into skeletal muscle as an extrahepatic site for engraftment, the engineered hepatic grafts provided life-saving support in models of acute, fulminant, and chronic liver failure that recapitulates these clinical diseases.

CONCLUSIONS

SAPNF-engineered hepatic constructs engrafted and functioned as hepatic tissues within the muscle to provide life-sustaining liver support. These engineered tissue constructs contained no animal products that would limit their development as a therapeutic approach.

A newly developed bioartificial pancreas successfully controls blood glucose in totally pancreatectomized diabetic pigs

Construction of a safe and functional bioartificial pancreas (BAP) that provides an adequate environment for islet cells may be an important approach to treating diabetic patients. Various types of BAP devices have been developed, but most of them involve extravascular implantation of islets in microcapsules or diffusion chambers. These devices have poor diffusive exchange between the islets and blood, and often rupture. To overcome these problems, we developed a new type of BAP composed of polyethylene-vinyl alcohol (EVAL) hollow fibers that are permeable to glucose and insulin and a poly-amino-urethane-coated, non-woven polytetrafluoroethylene (PTFE) fabric that allows cell adhesion. Porcine islets attached to the surface of the PTFE fabric, but not to the surface of the EVAL hollow fibers, allowing nutrient and oxygen exchange between blood flowing inside the fibers and cells outside. We inoculated this BAP with porcine islets and connected it to the circulation of totally pancreatectomized diabetic pigs. We found that blood glucose levels were reduced to a normal range and general health was improved, resulting in longer survival times. In addition, regulation of insulin secretion from the BAP was properly controlled in response to glucose both in vitro and in vivo. These results indicate that our newly developed BAP may be a potential therapy for the treatment of diabetes in humans.

Isolation and propagation of a human CD133(-) colon tumor-derived cell line with tumorigenic and angiogenic properties

It has been proposed in human colorectal cancers (CRC) a minority subset of cancer cells within tumors able to initiate tumor growth, defined as cancer stem cells (CSC). Solid human primary colonic and its ovarian metastatic cancer tissues were collected from fresh surgical samples and subsequent xenografts were established in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. The resulting tumors were disaggregated into single-cell suspensions and a CD133(-) cell line (NANK) was newly established and analyzed by flow cytometry. Surface markers of progenitor cells were immunophenotypically analyzed, and expression of stem cell and cancer-related genes was characterized. Secreted angiogenesis-associated molecules were investigated by proteomic array technology. Finally, different numbers of NANK were implanted and their tumor-initiating properties were investigated in NOD/SCID mice. Intraperitoneal injection of NANK in NOD/SCID mice induced tumors with developing progressive peritoneal dissemination and ascites. NANK cells maintained a differentiated phenotype and reproduced the full morphologic and phenotypic heterogeneity of their parental lesions. Noticeably, NANK lacked the expression of conventional CSC markers CD133 and CD44, self-renewal genes Oct-4 and Nanog, but showed the expression of an important gastrointestinal development marker CDX-2 and BMI-1 that is essential in regulating the proliferative activity of normal and leukemic stem cells. In addition, NANK secreted high amounts of important angiogenic cytokines. These results provide a novel and extensive model in human CSC for studying the generation and maintenance of phenotypic heterogeneity in CRC.

Increased transfusion-free survival following auxiliary pig liver xenotransplantation

BACKGROUND

Pig to baboon liver xenotransplantation typically results in severe thrombocytopenia and coagulation disturbances, culminating in death from hemorrhage within 9 days, in spite of continuous transfusions. We studied the contribution of anticoagulant production and clotting pathway deficiencies to fatal bleeding in baboon recipients of porcine livers.

METHODS

By transplanting liver xenografts from α1,3-galactosyltransferase gene-knockout (GalT-KO) miniature swine donors into baboons as auxiliary organs, leaving the native liver in place, we provided the full spectrum of primate clotting factors and allowed in vivo mixing of porcine and primate coagulation systems.

RESULTS

Recipients of auxiliary liver xenografts develop severe thrombocytopenia, comparable to recipients of conventional orthotopic liver xenografts and consistent with hepatic xenograft sequestration. However, baboons with both pig and native livers do not exhibit clinical signs of bleeding and maintain stable blood counts without transfusion for up to 8 consecutive days post-transplantation. Instead, recipients of auxiliary liver xenografts undergo graft failure or die of sepsis, associated with thrombotic microangiopathy in the xenograft, but not the native liver.

CONCLUSION

Our data indicate that massive hemorrhage in the setting of liver xenotransplantation might be avoided by supplementation with primate clotting components. However, coagulation competent hepatic xenograft recipients may be predisposed to graft loss related to small vessel thrombosis and ischemic necrosis.