OBJECTIVETo understand and improve the transdifferentiation of pancreatic stem cells into islet cells through isolation, cultivation and transdifferentiation of adult human pancreatic duct cells.

METHODSA portion of adult human pancreas was digested with collagenase, followed by incontinuous density gradient to separate islets from the acinar and ductal tissue. Duct epithelial cells were cultivated in CMRL1066 and then in serum-free DMEM/F12 medium with the addition of growth factors for 27 days. Samples were taken at different time points for light and electron microscopic examination and for immunocytochemical study with antibodies against transdifferentiation gene PDX-1 and protein CK-19. Amylase and insulin contents in the medium were assayed.

RESULTSA large number of duct epithelial cells were harvested after the isolation of islets. Some duct epithelial cells were PDX-1 and CK-19 positive at day one and duct epithelial cells proliferated and expanded rapidly and then transdifferentiated into stem cells and finally 3D islets. 760 islets were harvested from each gram of pancreatic tissue on day 27.

CONCLUSIONSAdult pancreatic duct cells are potential stem cells and could be transdifferentiated into islet cells in vitro under appropriate conditions.

Adult ; Cell Differentiation ; physiology ; Humans ; Islets of Langerhans ; cytology ; Pancreas ; cytology ; Stem Cells ; cytology

OBJECTIVE: To investigate islet graft survival and function after co-culture and co-transplantation with vascular endothelial cells (ECs) in diabetic rats. METHODS: We isolated ECs, and assessed the viability of isolated islets in a group of standard culture and a group of co-culture with ECs. Then we put the diabetic rats in 4 groups: an islet transplantation group, an islet graft with EC transplantation group, an EC transplantation group, and a PBS control group. Blood glucose and insulin concentrations were measured daily. Cell morphology and cell markers were investigated by immunohistochemical staining and electron microscope. RESULTS: Normal morphology was shown in more than 90% of AO/PI staining positive islets while co-cultured with ECs for 7 days. Insulin release assays showed a significantly higher simulation index co-culture except for the first day (P<0.05). There was a significant difference in concentrations of blood glucose and insulin among the 4 groups after 3 days after the transplantation (P<0.05). CONCLUSION EC-islet co-culture can improve the function and survival of isolated islets in vitro, and EC-islet co-transplantation can effectively prolong the islet graft survival in diabetic rats.
Animals ; Blood Glucose ; analysis ; Coculture Techniques ; Diabetes Mellitus, Experimental ; Endothelial Cells ; cytology ; Graft Survival ; Insulin ; blood ; Islets of Langerhans ; cytology ; Islets of Langerhans Transplantation ; Rats

OBJECTIVETo obtain massive human pancreatic islets with modified techniques and evaluation of the islets for the clinical allo-transplantation to treat type I and II diabetes.

METHODS28 consecutive adult human pancreata were isolated with modified automated techniques. Islets were purified using continuous density gradient. The islet yield was counted with international standard known as islet equivalent (IEQ). The function of the isolated islets was evaluated by measuring DNA/insulin ratio, static glucose stimulating test in vitro and transplanting the islets into diabetic nude mice in vivo followed by abdominal glucose tolerance test and C peptide measurement.

RESULTSThe yield of 28 consecutive human pancreata isolations ranged from 5 000 to 1 030 000 IEQs/pancreas with the average of 291 635 IEQs/pancreas. The first 13 isolations yielded 49 123 IEQs/pancreas, 846 IEQs/g and, purity 87% in average. The remained 15 isolations after the modifications yielded 501 813 IEQs/pancreas, 7 003 IEQs/g and purity 89% in average. The results of in vitro SGS showed good response to the different glucose concentration. 34 diabetic nude mice were transplanted under the renal capsule with the freshly isolated islets. 29 out of 34 diabetic mice obtained normoglycemia within 12 hours and the glucose tolerance tests were near normal. Serum C peptide level of transplanted mice is close to that of the control group.

CONCLUSIONSMassive human islets can be isolated with the modified techniques. Quality assessment of these islets both in vitro and in vivo has indicated that these high quality human islets could be used for the clinical allogeneic islet transplantation.

Adult ; Animals ; Cell Separation ; methods ; Diabetes Mellitus, Experimental ; surgery ; Glucose ; Humans ; In Vitro Techniques ; Islets of Langerhans ; cytology ; drug effects ; physiology ; Islets of Langerhans Transplantation ; Mice ; Mice, Nude ; Transplantation, Heterologous

BACKGROUNDGlobally, 180 million people suffer from diabetes mellitus. Islet transplantation is believed to be an almost ideal therapy for insulin-dependent patients. How to maintain the viability and the function of isolated human islets is a challenge in clinical practice. Sertoli cells are considered 'nurse cells' in the seminiferous tubules and have been used in cell graft protocols for neurodegenerative diseases and diabetes in many studies. Many researchers have used immature murine testes as the primarily source of Sertoli cells in islet transplantation because they are easily purified. Mature human Sertoli cells have been seldom investigated. In the present study, we developed a method for the isolation and culture of Sertoli cells derived from adult human testes, and investigated their effects on the function of allogeneic islets when they were cultured together in vitro.

METHODSAdult Sertoli cells were prepared successfully by two-step enzyme digestion with trypsin, collagenase and hyaluronidase. They were identified by morphological characteristics and their activity was determined by MTT colorimetry over a 28-day culture time in vitro. A glucose-stimulated insulin secretion test was performed to detect the effects of Sertoli cells on allogeneic islets' function when they were co-cultured for 21 days in vitro.

RESULTSIn cultured cells, mature human Sertoli cells accounted for more than 90% of total cells. The activity of Sertoli cells reached 95% and they remained highly cytoactive for a long time in vitro (P > 0.05). Compared with the islets cultured alone, the co-cultured islets with allogeneic Sertoli cells maintained higher sensitivity to glucose stimulation for the duration of the experiment (P < 0.01).

CONCLUSIONSA method of isolation and culture of Sertoli cells from adult testes has been established. Sertoli cells could enhance allogeneic islets' function when they were co-cultured in vitro. They could be a helper cell in islet transplantation.

Adult ; Cell Separation ; methods ; Cell Survival ; Cells, Cultured ; Coculture Techniques ; Humans ; Islets of Langerhans ; physiology ; Islets of Langerhans Transplantation ; Male ; Sertoli Cells ; cytology ; physiology

Pdx-1, an important transcription factor highlighting in the early pancreatic development, islet functions and pancreatic disorders, needs to be more investigated in zebrafish, and siRNA is still seldom applied in zebrafish embryo-related research. Our aim was to explore the role of pdx-1 in pancreatic development of zebrafish embryos by using siRNA approach. Microinjection, reverse transcriptase-PCR (RT-PCR), in situ hybridization and immunofluorescent staining were used in this research, and the morphology of the islet in normal zebrafish embryos, and in those treated with the siRNA specific to pdx-1 (siPDX-1) or siGFP was observed and compared. The expression of pdx-1 was detected in the stages of 1-cell, 2-cell, 4-cell, 8-cell, 16-cell, 16-hour by RT-PCT. The in situ hybridization and immunofluorescent staining results showed that siPDX-1 disturbed the formation of the islet in zebrafish embryos. Pdx-1 played multiple roles in maintaining the phenotype of the islet during embryogenesis in zebrafish.
Embryo, Nonmammalian ; Homeodomain Proteins/genetics ; Homeodomain Proteins/*metabolism ; Islets of Langerhans/cytology ; Islets of Langerhans/*embryology ; Islets of Langerhans/metabolism ; RNA Interference ; RNA, Small Interfering/*genetics ; Trans-Activators/genetics ; Trans-Activators/*metabolism ; Zebrafish

OBJECTIVETo compare the effect of continuous and discontinuous density gradient centrifugation for purification of human pancreatic islets with COBE 2991 cell processor.

METHODSHuman pancreases were obtained from brain-dead donors and stored in cold UW solution. The connective tissues were removed from the pancreases, and the pancreatic ducts were perfused with a cold enzyme (Liberase). The islets were then separated by gentle mechanical dissociation and purified with discontinuous (10 pancreases) or continuous (8 pancreases) gradients of HCA-Ficoll in COBE 2991 cell processor. Samples were collected in duplicate for determination of the quantity of islets, islet equivalents (IEQ), and the purity.

RESULTSThe weights of the pancreases before and after connective tissue removal and pancreas duct perfusion, and the quantity of islets obtained (including islets quantity of different diameters and total IEQ) after dissociation were not significantly different. Continuous gradient of HCA-Ficoll, compared with discontinuous gradient, resulted in significantly greater final islet quantity (55,000 IEQ vs 206,000 IEQ, P=0.000) and islet purity (58.0%-/+8.0% vs 33.5%-/+10.3%, P=0.000) and also greater number of islets with a diameter lager than 200 microm (P<0.01).

CONCLUSIONContinuous density gradient centrifugation can be more effective than discontinuous gradient in islet purification.

Cell Count ; Cell Separation ; methods ; Centrifugation, Density Gradient ; methods ; Humans ; Islets of Langerhans ; cytology ; Organ Size

OBJECTIVETo establish the methods for isolation, purification and function identification of Syrian golden hamster islets.

METHODSThe Langerhans islets were isolated and purified from golden hamster pancreas by intra-ductal collagenase V perfusion and discontinuous Ficoll density gradient centrifugation. After isolation, the islet yield and purity were evaluated with DTZ staining. The islet function was assessed using glucose-stimulated insulin secretion test.

RESULTSThe total number of purified islets from one donor hamster was 359-/+35 islet equivalent (IEQ), with the purity and viability of the isolated islets of more than 90%. In response to glucose stimulations at 5.8 and 16.7 mmol/L, the secretion of insulin by the islets was 3.29-/+0.3 and 11.12-/+0.57 mU/L, respectively, showing a 2.28-fold higher insulin release by high-concentration than by low- concentration glucose stimulation (P<0.01).

CONCLUSIONThe methods of collagenase V digestion and gradient centrifugation result in high yield and high purity of the isolated hamster islets.

Animals ; Cell Separation ; methods ; Cricetinae ; Insulin ; secretion ; Islets of Langerhans ; cytology ; Male ; Mesocricetus

OBJECTIVETo isolate human amniotic mesenchymal cells (hAMCs) and investigate their transdifferentiation ability into islet-like cells in vitro.

METHODSHuman amnion was treated with the trypsin/EDTA to remove the amniotic epithelial cells and then incubated with collagenase I and dispase at 37 degrees celsius; overnight. The cells were collected by centrifugation and identified for the expressions of vimentin and SSEA-4 using immunofluorescence assay and for CD29, CD90, CD34, and CD45 using flow cytometry. RT-PCR was performed to detect the expressions of ACTG2, ACTA2, MMP2, Cripto, Sox2, LEFTYA, nanog, and Oct-4 in the cells. The differentiation potential of the isolated cells into inslet-like cells was assessed after a 14-day induction with the inducing factors by RT-PCR and immunofluorescence assay.

RESULTSThe hAMCs were capable of in vitro proliferation and passaging for 10 passages while retaining the normal karyotype. The isolated cells were positive for staining of vimentin and SSEA-4 and negative for CD34 and CD45; the CD29 and CD90 cells accounted for (91.5∓9.93)% and (48.7∓9.47)% of the cells, respectively. The hAMCs expressed several pluripotency-related genes, including Cripto, Sox2, LEFTYA, nanog, and Oct-4. After induction, endocrine-related genes were expressed in the islet-like cells, including PDX1, ngn3, insulin and glucagon.

CONCLUSIONWe have successfully established the method for isolating hAMCs, which possess the potential of differentiation into islet-like cells in vitro.

Amnion ; cytology ; Cell Culture Techniques ; methods ; Cell Transdifferentiation ; physiology ; Cells, Cultured ; Female ; Humans ; Islets of Langerhans ; cytology ; Mesenchymal Stromal Cells ; cytology

OBJECTIVETo explore the feasibility of using a virus-free system in the induction of umbilical cord derived mesenchymal stem cells (UC-MSCs) into insulin-secreting cells.

METHODSMSCs were isolated from human umbilical cord and induced into insulin-secreting cells with a three-stage method. The mRNA expression levels of foxa2, sox17, pdx1, ngn3, pax4, insulin, and glut-2 were compared between induced and non-induced groups by RT-PCR in each stage. The distribution pattern of insulin and c-peptide were detected by immunofluorescence staining and observed by fluorescence microscopy. Insulin and c-peptide secretion and glucose responsiveness were detected by enzyme-linked immunosorbent assay (ELISA).

RESULTSTranscription factors foxa2, sox17, pdx1, ngn3, pax4, insulin, and glut-2 were expressed in the induced cells. The mRNA expression levels of foxa2 and sox17 were significantly higher in the induced group than those in non-induced group in the first stage (all P < 0.05), pdx1, ngn3, and pax4 were significantly higher in the induced cells than those in non-induced cells in the second stage (all P < 0.05), and insulin and glut-2 expressions were significantly up-regulated in the induced group at last stage (all P < 0.05). Immunofluorescence staining showed that insulin and c-peptide were located in the cytoplasm of more than 90% of induced cells. ELISA showed that total intracellular insulin content of the induced cells contained up to (346.3 739 +/- 32.5 149) microU/ml, which was significantly higher than insulin in non-induced cells (17.69 +/- 1.46) microU/ml (P < 0.01). C-peptide content of the induced cells measured up to (195.10 +/- 8.88) pmol/L/h (P < 0.01), when exposed to 5.5 mmol/L glucose (P < 0.01). When stimulated with 22 mmol/L glucose, the c-peptide content of the induced cells increased to (340.99 +/- 7.91) pmol/L/h (P < 0.01 ).

CONCLUSIONThe umbilical cord derived MSCs can be efficiently induced into insulin-secreting cells via a virus-free system.

Cell Culture Techniques ; Cell Differentiation ; Cells, Cultured ; Humans ; Islets of Langerhans ; cytology ; Mesenchymal Stromal Cells ; cytology ; Umbilical Cord ; cytology

OBJECTIVETo establish a method for isolating and culturing human amniotic epithelial cells (hAECs) in a serum-free medium and investigate their transdifferentiation ability into islet-like cells.

METHODSThe culture condition of hAECs was optimized using DMEM with different supplements. The genetic stability of the tenth-passage cells was assessed by chromosome analysis and G-banding method. The stem cell characteristics of the cells were identified by examination of the surface markers using immunofluorescence methods. The endocrine-related genes and hormones of the cells were tested after induced differentiation into islet-like cells.

RESULTSThe hAECs allow stable passaging in the presence of 10 ng epidermal growth factor (EGF) in the culture medium. After 10 passages, the cells maintained a normal karyotype and G-banding profile. The hAECs expressed many multi-potent stem cell markers, including SSEA4, TRA-1-60, and TRA-1-81. After induced differentiation, the endocrine-related genes were expressed in the islet-like cells, including PDX1, ngn3, insulin and glucagon. Insulin secretion increased in the differentiated islet-like cells in response to high glucose exposure.

CONCLUSIONWe established a method for isolating and expanding the hAECs in a serum-free medium. hAECs possess stem cell characteristics and can be induced to differentiate into islet-like cells in vitro.

Amnion ; cytology ; Cell Culture Techniques ; methods ; Cell Differentiation ; Cells, Cultured ; Epithelial Cells ; cytology ; secretion ; Humans ; Insulin ; secretion ; Islets of Langerhans ; cytology ; Stem Cells ; cytology ; secretion