Widespread Distribution of Adenovirus-Transduced Monkey Amniotic Epithelial Cells after Local Intracerebral Injection: Implication for Cell-Mediated Therapy for Lysosome Storage Disorders

Cell-mediated therapy for mucopolysaccharidosis type VII (MPSVII) was studied using monkey amniotic epithelial cells (mAEC). The cells were transduced with a recombinant adenovirus expressing human β-glucuronidase (GUSB), and cells overexpressing GUSB were generated. The cells expressed 2000-fold higher activities than the endogenous GUSB activities of nontransduced mAEC, demonstrating that mAEC were successfully transduced with adenoviral vectors. These cells also secreted high levels of GUSB. To clarify the cross-correction of GUSB secreted from mAEC, the conditioned medium containing high levels of GUSB was added into the medium for culturing human or murine fibroblasts established from an MPSVII patient or a mouse model of the disease. Dramatic increases in GUSB activities were observed in both fibroblasts. We then transplanted the cells transduced with an adenovirus expressing LacZ into the caudate-putamen of monkey brain. Survival and distribution of the transplanted cells 1 month after the treatment were evaluated. Histochemical analysis showed that LacZ-positive cells were widely distributed in the brain, suggesting that the transplanted cells had migrated and were distributed even at regions far from the implantation site. These findings suggest that local intracerebral engraftment of genetically engineered amniotic epithelial cells is favorable for the treatment of lysosome storage disorders, whose pathological abnormalities are not restricted to specific regions of the brain.

Cytological Examination of Rat Amniotic Epithelial Cells and Cell Transplantation to the Liver

It is hoped that amniotic epithelial cells can be useful in cell-mediated gene therapy. We report here an experimental cell transplantation model of amniotic cells in rats. There is an anatomical difference between human and rodent embryos. We established a method to isolate amniotic cells that are equivalent to human amniotic epithelial cells. An amniotic membrane distinct from the yolk sac was carefully collected and teased in saline containing deoxyribonuclease and hyaluronidase, followed by collagenase digestion. The cell yield was approximately 106 cells per pregnant female (105 cells per fetus), roughly in proportion to the age of fetus used, and 60% of the isolated cells were attached to the dish under culture conditions. Telomerase activity was higher in the cells isolated from fetuses in the middle stage (day 13.5 to 15.5) than in the late stage (day 17.5 to 21.5). Adherent cells exhibited two to three times more cell division, resulting in a ninefold increase in the number of cells. Immunohistochemical analysis revealed that approximately half of the adherent cells were albumin positive and formed clusters. The senescent cells survived for 2 months without apparent morphological changes. The adherent cells were able to be stored in liquid nitrogen and had a viability of 70% when thawed. Gene transduction with adenovirus vector was highly effective for rat amniotic cells. Transplantation of lacZ transfected amniotic cells into syngeneic rat liver resulted in the integration of the transplanted cells in the liver structure and the cells survived for at least 30 days.

In Vitro Study of Encapsulation Therapy for Fabry Disease Using Genetically Engineered CHO Cell Line

Fabry disease is an X-linked recessive disorder caused by a deficiency of the lysosomal hydrolase α-galac-tosidase A (α-gal). The deficiency of this enzyme leads to the systemic deposition of ceramide trihexoside (CTH) in various tissues and organs. Enzyme replacement using IV doses of recombinant human α-gal produced in CHO cells or in human fibroblasts is currently being evaluated in clinical trials as a potential therapy for this disease. However, it requires lifelong therapy involving a large amount of purified α-gal. As a novel approach for treatment of Fabry disease we used polymer encapsulated Chinese hamster ovary (CHO) cells genetically modified to express α-gal. The secreted high levels of α-gal passed through the semipermeable polymeric membrane. Using coculture system with Fabry fibroblasts, the secreted enzyme was taken up in cells, resulting in reduced accumulation of CTH in Fabry fibroblasts. This in vitro study demonstrated that an encapsulated α-gal-secreting cell line can be used to treat Fabry mice by transplantation in vivo. Judging from the protection against immune rejection by a semipermeable synthetic membrane, this novel approach may be applied to treat patients with Fabry disease and other lysosomal storage diseases.

Immunostaining of Human Amniotic Epithelial Cells: Possible use as a Transgene Carrier in Gene Therapy for Inborn Errors of Metabolism

Immunoreactivity of human cultured amniotic epithelial (AE) cells was investigated to evaluate the possible use of these cells as a transgene carrier in gene therapy for inborn errors of metabolism. AE cells were prepared and cultured by the methods described previously. Flow cytometry analysis revealed that these cells did not express any class II antigen at all on their surfaces. But the class I antigen was slightly expressed on their surfaces. Immunoperoxidase staining was slightly positive as to the class I antigen but not to the class II antigen at all. pSV-β-galactosidase was transfected into AE cells by means of electroporation, followed by staining of the cells with X-gal. Several cells in 60 mm dish expressed β-galactosidase activity. The possible gene transfer of β-galactosidase into cultured AE cells may suggest that these cells could be used as a transgene carrier in gene therapy for inborn errors of metabolism.

Transplantation of Amniotic Epithelial Cells into Fetal Rat Liver by In Utero Manipulation

It has been hoped that amniotic epithelial cells would be a gene carrier to neural and hepatic tissue, because of 1) the presence of neural and hepatic stem-like cells, 2) the ability to cryopreserve them, 3) long-term survival in the transplanted site, and 4) few ethical problems concerning procurement. But transplantation of a sufficient number of cells to adult tissue needs large-scale cell supply and may lead to vascular embolism. We attempted transplantation of amniotic epithelial cells into fetal liver, because 1) the fetal liver is at the proliferative stage, 2) the number of cells required is small, and 3) the fetal stage is advantageous for the induction of immunological tolerance. Amniotic epithelial cells from day 18.5–20.5 fetuses were transfected with adenoviral AdlacZ and harvested to inject into fetal rat liver of the syngeneic strain (day 18.5–20.5). The efficacy of cell transplantation into the liver increased in the order: intraplacental < intraumbilical vein < intrahepatic route. LacZ-transfected amniotic cells (1–8 × 105 cells), hepatocytes (5 × 105 cells), or AdlacZ vector solution (1.7 × 107 pfu) were injected through the uterine membrane into the liver. Transplanted cells formed a cellular mass and survived for up to 14 days after birth, whereas lacZ-transfected cells were rapidly decreased after the injection of AdlacZ vector or rat hepatocytes as a gene carrier so that the use of amniotic epithelial cells as a gene carrier will result in long-term expression of exogenous genes in the liver.

Characteristics and thrombogenicity of factor IX concentrate

Thrombogenicity of the factor IX concentrate and its clinical use for stoppage of the bleeding in the case of hemophilia A with inhibitor were reported. (1) Factor IX concentrate contained the coagulation factors as prothrombin complex (factors II, VII, IX and X); Thrombin and factor Xa. (2) Prothrombin in the factor IX concentrate could be converted to thrombin without any additional procoagulant such as thromboplastin or factor V, but in just 2.5M glycine solution by the effect of factor Xa. (3) The infusion of factor IX concentrate into a rabbit induced DIC promptly which was proved by autopsy and coagulation-fibrinolytic studies. (4) Factor IX concentrate showed a great efficacy in stopping the bleeding in the case of hemophilia A with inhibitor.

Hypoxia enhances the induction of human amniotic mesenchymal side population cells into vascular endothelial lineage

Human amniotic mesenchymal side population (hAM-SP) cells have pluripotency and weak immunogenicity, and have promising roles in the field GAPDH of regenerative medicine. The aim of the present study was to determine whether hypoxic conditions induce the differentiation of hAM-SP cells into the vascular endothelial lineage. Mesenchymal cells were isolated from enzyme-treated amniotic membranes and stained with Hoechst 33342. The hAM-SP cells were negatively sorted by FACS and cultured in induction medium containing vascular endothelial growth factor (VEGF) under normoxic (20% O2) or hypoxic (1% O2) conditions for 1 or 2 weeks. The expression of endothelial markers such as kinase domain region (KDR), fms-like tyrosine kinase (Flt)-1, von Willebrand factor (vWF), vascular endothelial (VE)-cadherin and human vascular cell adhesion molecule (VCAM) at the gene and protein level was evaluated by real-time PCR and fluorescent immunostaining, respectively. The gene expression of KDR, Flt-1, VE-cadherin and vWF peaked after 2 weeks of culture. The protein expression of KDR and VE-cadherin was also enhanced after 2 weeks of culture under hypoxic conditions. To confirm the involvement of hypoxia-inducible factor (HIF) in the induction under hypoxic conditions, the expression of genes which are known to be upregulated by HIF was analyzed by DNA microarray. The expression of these genes increased under hypoxic conditions. hAM-SP cells cultured under hypoxic conditions differentiated into the vascular endothelial lineage, probably due to upregulation of the gene expression associated with angiogenesis through activation of the HIF system.

Multilineage Potential of Side Population Cells from Human Amnion Mesenchymal Layer

Side population (SP) cells were isolated by FACS from a human amnion mesenchymal cell (AMC) layer soon after enzyme treatment. The yield of SP cells from AMC layer (AMC-SP cells) was about 0.1–0.2%. AMC-SP cells grew well with cell doublings of 40–80 days of culture. FACS profiles and immunocytostaining showed that AMC-SP cells were composed of two different cells immunologically: HLA I–/II- and HLA I+/II–. Oct-3/4 was detected in the nucleus of AMC-SP cells, when the culture was examined at the third, sixth, and 10th passages. RT-PCR showed that AMC-SP cells expressed the Oct-4, Sox-2, and Rex-1 genes. Immunocytochemistry revealed that all AMC-SP cells were vimentin+, CK19+, and nestin+. In addition, flow cytometry analysis showed that SP cells had high expression of CD13, CD29, CD44, CD46, CD49b, CD49c, CD49e, CD59, CD140a, and CD166 but low expression of CD 49d, and CD51. No evidence of expression was obtained for CD34, CD45, CD49a, CD56, CD90, CD105, CD106, CD117, CD133, CD271, or Flk-1. Upon appropriate differentiation protocols, AMC-SP cells differentiated to several cell lineages such as neuroectodermal, osteogenic, chondrogenic, and adipogenic cells. These results indicate that AMC-SP cells have multilineage potential to several cell lineages with unique immunological characteristics such as HLA I–/II– or HLA I+/II–. AMC-SP cells should be of considerable value for regenerative medicine because they do not induce acute rejection after allotransplantation, they do not cause ethical issues, and there is no limit of supply.

256 EFFECT OF EPIDERMAL GROWTH FACTOR ON IN VITRO MATURATION OF CYNOMOLGUS MONKEY (MACACA FASCICULARIS) OOCYTES

Collected oocytes include not only mature oocytes (metaphase II: MII), but also immature oocytes (germinal vesicle: GV, and metaphase I: MI). To establish a dependable artificial indoor breeding program in cynomolgus monkeys, we are planning to carry out in vitro maturation (IVM) using GV and MI oocytes. In this study, we attempted to determine whether different types of feeder layers and epidermal growth factor (EGF) were effective for IVM. Cumulus–oocyte complexes (COCs) were collected from ovaries of 4–10-year-old female cynomolgus monkeys stimulated by the combination of FSH (25 IU kg–1 × 9 days) and hCG (400 IU kg–1) (Torii 2000 Primates 39, 399–406). Oocytes were classified by morphological features: oocytes retaining an intact germinal vesicle nucleus (GV); oocytes that had undergone germinal vesicle breakdown without polar body formation (MI); and oocytes with a first polar body (MII). GV and MI oocytes were co-cultured on monkey cumulus cells (MCC), monkey follicular ovarian cells (MFOC), monkey oviductal cells (MOC), or human solubilized amnion product (HSAP), with TCM-199+10% fetal bovine serum containing epidermal growth factor (EGF; 10 ng mL–1 or 20 ng mL–1). The maturation rate from GV to MII oocytes was 6.7% (MCC), 18.0% (MFOC), 35.7% (MOC), and 28.6% (HSAP) (Table 1). Although higher maturity was observed in MOC and HSAP, the effect of EGF was not found in co-cultures using any feeder layers. The maturation rate from MI to MII oocytes was 33.3% (MCC), 27.8% (MFOC), 55.6% (MOC), and 44.0% (HSAP) (Table 1). The highest maturation rate from GV and MI was observed in co-cultures using MOC. The maturation rate from MI to MII oocytes in the presence of 10 ng mL–1 EGF was 75.0% (MCC) and 73.7% (HSAP) (Table 1), whereas the rate in the presence of 20 ng mL–1 EGF was 59.1% (MCC), 64.3% (MFOC), 92.3% (MOC), and 60.0% (HSAP) (Table 1). Thus, the best maturation rate was a co-culture using MOC as a feeder layer with 20 ng mL–1 EGF. According to our results, maturation rate during IVM depends on the cellular type of feeder layers and the concentration of EGF. EGF is especially effective for maturity from MI to MII oocytes, but not from GV to MI or MII oocytes. Thus, IVM should be carred out under optimal culture conditions, including suitable feeder layer and media plus supplements. In the future, it is important that intracytoplasmic sperm injection be carried out using in vitro-matured MII oocytes for establishment of an artificial indoor breeding program in cynomolgus monkeys. Table 1. Number of matured oocytes co-cultured with different feeder layers and EGF

Concise review: isolation and characterization of cells from human term placenta: outcome of the first international Workshop on Placenta Derived Stem Cells

Placental tissue draws great interest as a source of cells for regenerative medicine because of the phenotypic plasticity of many of the cell types isolated from this tissue. Furthermore, placenta, which is involved in maintaining fetal tolerance, contains cells that display immunomodulatory properties. These two features could prove useful for future cell therapy-based clinical applications. Placental tissue is readily available and easily procured without invasive procedures, and its use does not elicit ethical debate. Numerous reports describing stem cells from different parts of the placenta, using nearly as numerous isolation and characterization procedures, have been published. Considering the complexity of the placenta, an urgent need exists to define, as clearly as possible, the region of origin and methods of isolation of cells derived from this tissue. On March 23-24, 2007, the first international Workshop on Placenta Derived Stem Cells was held in Brescia, Italy. Most of the research published in this area focuses on mesenchymal stromal cells isolated from various parts of the placenta or epithelial cells isolated from amniotic membrane. The aim of this review is to summarize and provide the state of the art of research in this field, addressing aspects such as cell isolation protocols and characteristics of these cells, as well as providing preliminary indications of the possibilities for use of these cells in future clinical applications.

Uptake and Decarboxylation of l-3,4-Dihydroxyphenylalanine in Cultured Monkey Placenta Amniotic Epithelial Cells

In this study we tested the ability of monkey amniotic epithelial cells (MAEC) to take up and decarboxylate l-3,4-dihydroxyphenylalanine (l-DOPA) by incubating the cells in buffer containing l-DOPA under different experimental conditions followed by assaying cellular dopamine (DA) content using high performance liquid chromatography with electrochemical detection. Cellular contents of DA were significantly increased in a time- and l-DOPA-concentration-dependent manner, suggesting the uptake of l-DOPA by MAEC and indicating the presence of aromatic l-amino acid decarboxylase (AADC). This was confirmed by the decreased DA content in the presence of benserazide, an AADC inhibitor. Neither d-DOPA nor DA uptake blockers such as mazindol and GBR 12935 significantly affected l-DOPA uptake and hence DA levels. Further, synthesis of DA from l-DOPA was decreased in the presence of the amino acids tyrosine, phenylalanine and tryptophan, whereas the amino acids glycine and proline were without any significant effect. These findings suggest that MAEC have the capacity to selectively take up and decarboxylate l-DOPA with subsequent production of DA.

Immunological Characteristics of Amniotic Epithelium

We review recent experimental evidence of the immunosuppressive and immunogenic potential of amniotic epithelial cells. Since cryopreserved amniotic membrane (AM) has been used in clinical applications, much research has focused on the beneficial effects of amniotic stromal matrix rather than on the function of viable amniotic cells. However, viable human amniotic epithelial cells (HAECs) have been shown to elicit beneficial effects on secretion of anti-inflammatory factors. Topical application of culture supernatant from HAECs leads to profound suppression of suture-induced neovascularization in cornea and fewer major histocompatibility complex (MHC) class II antigen-presenting cells (APCs) in inflamed cornea after thermal cautery. Furthermore, expression of interleukin (IL)-1beta mRNA was suppressed in cauterized cornea. These results suggest that HAECs are a source of soluble anti-inflammatory factors that suppress corneal inflammation. However, viable amniotic epithelial cells display antigenicity and immunogenicity as allografts. Fresh allogeneic amniotic epithelium (AE) expresses MHC class I antigens and sensitizes recipients when placed in the eye, although long-term memory of allo-specific delayed hypersensitivity (DH) was not acquired. Allogeneic AE was clearly vulnerable to acute immune rejection in specifically sensitized recipients and recipients of repeated AE transplantation. We therefore suggest that immunogenicity of AE should not be ignored, and use of AM from different donor placentas should be emphasized when repeated AM transplantation is required in patients clinically.

Encapsulation Cell Therapy for Mucopolysaccharidosis Type VII Using Genetically Engineered Immortalized Human Amniotic Epithelial Cells

Mucopolysaccharidosis type VII (MPSVII) is a lysosomal storage disease resulted from a deficiency of the enzyme beta-glucuronidase (GUSB), which is necessary for degradation of glycosaminoglycans (GAGs). The deficiency of GUSB causes progressive accumulation of GAGs and subsequent lysosomal distension in multiple tissues, including the central nervous system (CNS). In murine experiments, bone marrow transplant, enzyme replacement, viral vectors, and genetically modified cells were successfully used for correction of the visceral accumulation of GAGs, but little improvement was seen in the brain, because these therapeutic agents cannot cross the blood-brain barrier (BBB). Although direct intracerebral injection of GUSB-encoding viral vectors has been developed to bypass the BBB, the possibility of tumor formation and the toxicity of over-expressed GUSB have been reported. In this study, we generated immortalized human amniotic epithelial (IHAE) cells to maintain the effect of implantation, and encapsulated these cells to prevent harmful immunological response and tumor formation and to regulate the level of GUSB expression within the host. Moreover, we generated IHAE cells that over-express and secrete human GUSB following transduction with an adenoviral vector encoding human GUSB. Therapeutic efficacy for MPSVII was evaluated in and ex vivo experiments using these encapsulated genetically engineered GUSB-encoding IHAE cells. We confirmed that encapsulated genetically engineered IHAE cells could secrete significant amounts of GUSB outside the capsule in vitro and into the cerebral parenchyma of C3H mice seven days after the capsule implantation. Thus, encapsulation cell therapy using genetically engineered IHAE cells is an effective armamentarium for the treatment of MPSVII.

Progesterone, but not 17beta-estradiol, up-regulates erythropoietin (EPO) production in human amniotic epithelial cells

Human amniotic epithelial (HAE) cells have great potential for successful use in cell therapy, since they do not cause acute rejection upon allotransplantation. However, to date, HAE cells have not well been studied. We previously reported that HAE cells produce erythropoietin (EPO), which is known to be a regulator of hematopoiesis, and that the induction mechanism of HAE cells is unknown, although EPO production from HAE cells is not increased by hypoxia which induces several cell types to produce EPO. In this study, we determined whether female sex hormones, including progesterone and 17beta-estradiol, affect the EPO production of HAE cells. Bioactive measurement of EPO activity in the culture supernatants of HAE-SV40 cells, which were immortalized by transfection with a simian virus 40 large T antigen, revealed that EPO bioactivity was significantly increased by treatment with progesterone, but not 17beta-estradiol. Treatment of HAE-SV40 cells with progesterone transiently increased the EPO mRNA level by fivefold, while there was no change in response to 17beta-estradiol. Furthermore, the progesterone receptor (PR)-B was detected in both HAE cells and HAE-SV40 cells by Western blotting. These results suggest that EPO synthesis in HAE-SV40 cells is stimulated by progesterone, but not by 17beta-estradiol, and thus it is highly likely that the EPO synthesis of HAE cells is also regulated by progesterone.

Topical application of culture supernatant from human amniotic epithelial cells suppresses inflammatory reactions in cornea

Human amniotic epithelial cells (HAEC) may be a source of soluble anti-inflammatory factors. The purpose of this study is to determine the effect of topically applied HAEC culture supernatant on corneal inflammatory reactions. HAEC were obtained from a placenta and cultured for 48 hr, and the supernatant was collected. The conditioned medium from HAEC contained small amounts of human interleukin-1 receptor antagonist (IL-1ra). Intrastromal sutures were placed in the cornea of BALB/c mice to induce corneal neovascularisation. Superficial cauterisation was applied to induce recruitment or activation of antigen presenting cells (APCs) in the cornea without neovascularisation. HAEC conditioned medium, placebo, or recombinant human IL-1ra was topically applied three times daily for 2 weeks. Suture-induced corneal neovascularisation was evaluated microscopically for 8 weeks. The cauterised corneas were harvested at 2 weeks, and the MHC class II(+) APCs were quantified by immunofluorescent staining and confocal microscopy. Inflammatory cytokine gene expression in the cauterised corneas was analyzed by a multiprobe ribonuclease protection assay. Conditioned medium from HAEC led to a profound suppression of corneal neovascularisation and fewer MHC class II(+) APCs in the epithelium. In contrast, human IL-1ra was only slightly effective in suppressing corneal inflammatory reactions. mRNA expression of murine IL-1ra and IL-1beta in the cauterised corneas was markedly suppressed after application of the conditioned medium. These results suggest that HAEC are a source of soluble anti-inflammatory factors and that conditioned medium from HAEC contains factors other than IL-1ra that suppress corneal inflammation.

Human amnion mesenchyme cells express phenotypes of neuroglial progenitor cells

Previous studies from our laboratory showed that human amnion epithelial cells (AECs) have multiple functions, such as synthesis and release of catecholamines, acetylcholine, neurotrophic factors, activin, and noggin. In this study, we investigated the identity of neural progenitor cells in human amnion mesenchyme cells (AMCs), which lie immediately adjacent to the AECs. Cryostat sections revealed that vimentin expression was detected in the AMCs and CK19 in AECs. Vimentin-positive cells made up 97.5% of total cells tested in cultured AMCs. Interestingly, 3.6% of total AMCs expressed the phenotype CK19+/vimentin+, indicating coexpression of epithelial and mesenchyme cell markers. In culturing with bromodeoxyuridine (BrdU) for 24 hr, 66-82% of cells were found to be BrdU positive, suggesting that they have proliferating potency. By using RT-PCR, AMCs express mRNA of nestin and Musashi1. With a neural cell differentiating protocol, cell bodies extended long bipolar or complex multipolar processes. Nestin (87.7% of total cells tested) and Musashi1 (93.1%) were expressed in undifferentiated cells, and their positively stained cells increased in number slightly after induction. Undifferentiated cells were stained by anti-Tuj1 and NF-M, and their positively stained cells increased significantly in number after induction, to 72.8% and 46.0%, respectively. Meanwhile, glial fibrillary acidic protein-positive cells increased from 25.4% to 43.2% after induction. These studies demonstrate that AMCs have phenotypes of neuroglial progenitor cells and can be differentiated into neuroglial phenotypes by optimal differentiation protocol. Eventually, AMC-derived stem cells may be a favorable cell vehicle in regenerative medicine.

New GAA mutations in Japanese patients with GSDII (Pompe disease)

Glycogen storage disease type II (Pompe disease) is inherited by autosomal recessive transmission and caused by a deficiency of acid alpha-glucosidase (GAA), resulting in impaired degradation and lysosomal accumulation of glycogen. The GAA gene, responsible for this disease, has been mapped to chromosome 17q25.2-25.3. To date, more than 70 disease-causing mutations have been identified. In this study, we present four mutations found in three Japanese patients with the juvenile form of glycogen storage disease type II; three of these mutations were new (R224W, S619R, and R660H). The pathogenicity of these new mutations was verified by the loss of function of the mutant enzymes expressed in COS cells.

Implantation of human amniotic epithelial cells prevents the degeneration of nigral dopamine neurons in rats with 6-hydroxydopamine lesions

We recently found that human amniotic epithelial (HAE) cells secrete biologically active neurotrophins such as brain-derived neurotrophic factor and neurotrophin-3, both of which exhibit trophic activities on dopamine (DA) neurons. The present study explored whether implantation of HAE cells can be a possible means to deliver trophic factors into the brain to prevent the death of DA neurons in a rat model of Parkinson's disease. We first investigated the ability of HAE cells to produce factors capable of promoting DA cell survival in vitro, and then tested whether HAE cell grafts survive and prevent the death of nigral DA neurons in rats with 6-hydroxydopamine lesions. A treatment with conditioned medium derived from HAE cell cultures enhanced the survival of tyrosine hydroxylase (TH)-immunopositive DA cells in serum-free cultures. The conditioned medium also protected the morphological integrity of TH-positive neurons against toxic insult with 6-hydroxydopamine. HAE cells were grafted into the midbrain of immunosuppressed rats. The rats were then subjected to a unilateral nigrostriatal lesion induced by intrastriatal infusions of 6-hydroxydopamine. HAE cell transplants were found to survive without evidence for overgrowth 2 weeks postgrafting. The number of nigral DA cells, detected with either TH-immunohistochemistry or retrograde labelling with fluorogold, was significantly increased in rats given the grafts as compared to that in control animals without the grafts. The results indicate that HAE cells produce diffusible molecules that can enhance the survival of DA neurons. Although the factors that contribute to the currently observed effects remain to be fully determined, implantation of HAE cells could be a viable strategy to counteract the loss of DA neurons in Parkinson's disease.

Evidence of dopamine D1 receptor mRNA and binding sites in cultured human amniotic epithelial cells

In this study, we employed RT-PCR and radioligand binding studies to evaluate the gene expression and binding characteristics, respectively, of dopamine D(1) receptors in human amniotic epithelial cells (HAEC). The results showed that HAEC natively expressed D(1) receptor mRNA, as measured by RT-PCR, which was identical to that of human brain. Saturation binding studies using [(3)H]SCH 23390 demonstrated the presence of a high affinity D(1) site in HAEC with K(D) and B(max) values of 2.01+/-0.25 nM and 32.5+/-3.7 fmol/mg protein, respectively. Competition studies showed that selective D(1) antagonists were potent displacers of [(3)H]SCH 23390 binding with a potency order consistent with D(1) receptor characteristics. The current results present compelling evidence that HAEC natively express D(1) receptor mRNA and binding sites. The results also establish a primate cell model that can possibly be used for studying D(1) receptor signal transduction and molecular mechanisms and exploring newly developed drugs acting at these receptors.

Characterization of dopamine D2 receptor gene expression and binding sites in human placenta amniotic epithelial cells

This study was to investigate the presence of dopamine (DA) D(2)receptors mRNA and binding sites in human amniotic epithelial cells (HAEC). RT-PCR revealed that HAEC express DA D(2)receptor mRNA that is having 100 per cent homology with human DA D(2)receptors. Radioligand saturation binding studies showed a [3H]YM-09151-2 high affinity binding site with a K(D)and B(max)values of 0.53+/-0.09 nM and 119.6+/-8.5 fmol/mg protein, respectively. Competition experiments demonstrated that selective D(2)antagonists such as spiroperidol, domperidone and eticlopride potently competed with [3H]YM-09151-2 binding, whereas selective D(1)antagonists like SCH 23390 displayed weaker competition for the binding sites. The rank order of potency of these compounds in competing with [3H]YM-09151-2 for the binding sites was consistent with the pharmacology of the DA D(2)receptors. All competition curves were better fitted to a one-site model with a Hill coefficient around unity, indicating that [3H]YM-09151-2 is labelling a single population of receptors. These results provide evidence that HAEC natively express DA D(2)receptor mRNA and binding sites. Although the physiological function of D2 receptors in HAEC is currently unclear, the present results suggest that these cells could represent a source of human DA D(2)receptors without transformation or cloning procedures.

Characterization of the dopamine transporter gene expression and binding sites in cultured human amniotic epithelial cells

In this study we sought to investigate whether the dopamine transporter, DAT, and its binding sites are expressed in the human amniotic epithelial cells (HAEC) using reverse transcription-polymerase chain reaction (RT-PCR) and radioligand binding studies, respectively. The RT-PCR findings showed that HAEC expressed DAT mRNA with 100% homology to the human brain DAT. Saturation binding studies using [3H]mazindol showed a high affinity DAT binding site with K(D) and B(max) values of 12.32+/-1.67 nM and 82.7+/-9.74 fmol/mg protein, respectively. Competition experiments showed that selective DAT blockers are potent displacers of [3H]mazindol binding. The rank order of potency of the competing drugs is consistent with the pharmacology of the DAT. The present results provide compelling evidence that HAEC natively express the DAT mRNA and binding sites. More importantly, these results may suggest that HAEC is an appropriate human cell model for studying dopamine release and uptake processes and potential ligands at these sites.

Factors secreted by human amniotic epithelial cells promote the survival of rat retinal ganglion cells

We evaluated whether factors secreted by human amniotic epithelial cells (HAECs) have the neuroprotective effect on rat retinal ganglion cells (RGCs) purified by immunopanning. After culture in B27 complete medium containing B27 supplement, brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF) and forskolin, the medium was changed to: (1). medium containing N2 supplement and forskolin (N2 basal medium); (2). medium conditioned by HAECs containing N2 supplement and forskolin (HAEC-CM); and (3). N2 basal medium containing several neurotrophic factors. HAEC-CM promoted the RGC survival compared to N2 basal medium. The effect of HAEC-CM was significantly higher than that of BDNF, neurotrophin-3 and CNTF. These results suggest that HAECs may produce unknown neuroprotective factors, suggesting its potential for the treatment of RGC degenerative diseases.

Transplantation of amniotic epithelial cells into fetal rat liver by in utero manipulation

It has been hoped that amniotic epithelial cells would be a gene carrier to neural and hepatic tissue, because of 1) the presence of neural and hepatic stem-like cells, 2) the ability to cryopreserve them, 3) long-term survival in the transplanted site, and 4) few ethical problems concerning procurement. But transplantation of a sufficient number of cells to adult tissue needs large-scale cell supply and may lead to vascular embolism. We attempted transplantation of amniotic epithelial cells into fetal liver, because 1) the fetal liver is at the proliferative stage, 2) the number of cells required is small, and 3) the fetal stage is advantageous for the induction of immunological tolerance. Amniotic epithelial cells from day 18.5-20.5 fetuses were transfected with adenoviral AdlacZ and harvested to inject into fetal rat liver of the syngeneic strain (day 18.5-20.5). The efficacy of cell transplantation into the liver increased in the order: intraplacental < intraumbilical vein < intrahepatic route. LacZ-transfected amniotic cells (1-8 x 10(5) cells), hepatocytes (5 x 10(5) cells), or AdlacZ vector solution (1.7 x 10(7) pfu) were injected through the uterine membrane into the liver. Transplanted cells formed a cellular mass and survived for up to 14 days after birth, whereas lacZ-transfected cells were rapidly decreased after the injection of AdlacZ vector or rat hepatocytes as a gene carrier so that the use of amniotic epithelial cells as a gene carrier will result in long-term expression of exogenous genes in the liver.