Bone marrow-derived mesenchymal stem cells improve rat islet graft revascularization by upregulating ISL1.

Revascularization of the islet transplant is a crucial step that defines the success rate of patient recovery. Bone marrow-derived mesenchymal stem cells (BMSCs) have been reported to promote revascularization; however, the underlying cellular mechanism remains unclear. Moreover, our liquid chromatography-tandem mass spectrometry results showed that BMSCs could promote the expression of insulin gene enhancer binding protein-1 (ISL1) in islets. ISL1 is involved in islets proliferation and plays a potential regulatory role in the revascularization of islets. This study identifies the ISL1 protein as a potential modulator in BMSCs-mediated revascularization of islet grafts. We demonstrated that the survival rate and insulin secretion of islets were increased in the presence of BMSCs, indicating that BMSCs promote islet revascularization in a coculture system and rat diabetes model. Interestingly, we also observed that the presence of BMSCs led to an increase in ISL1 and vascular endothelial growth factor A (VEGFA) expression in both islets and the INS-1 rat insulinoma cell line. In silico protein structure modeling indicated that ISL1 is a transcription factor that has four binding sites with VEGFA mRNA. Further results showed that overexpression of ISL1 increased both the abundance of VEGFA transcripts and protein accumulation, while inhibition of ISL1 decreased the abundance of VEGFA. Using a ChIP-qPCR assay, we demonstrated that direct molecular interactions between ISL1 and VEGFA occur in INS-1 cells. Together, these findings reveal that BMSCs promote the expression of ISL1 in islets and lead to an increase in VEGFA in islet grafts. Hence, ISL1 is a potential target to induce early revascularization in islet transplantation.

Simultaneous blockade of the CD40/CD40L and NF-κB pathways prolonged islet allograft survival.

Activation of NF-κB pathway and co-stimulatory system CD40/CD40L promotes the inflammation, which plays a key role in the failure of islet graft. Therefore, the purpose of this study was to determine if simultaneous blockade of CD40/CD40L and IκB/NF-κB pathways could protect islet graft. Streptozocin-induced diabetic Wistar rats were transplanted intraportally with 2000 IEQ islets isolated from Sprague-Dawley rats. The rats were divided into five groups: nontreatment group, AdGFP-treated group, Ad-IκBα-treated group, Ad-sCD40LIg-treated group, and Ad-IκBα-IRES(2) -sCD40L-treated group. The islet graft mean survival time (MST), insulin expression of islet grafts, and the levels of cytokines in peripheral blood, were measured for the animals in each group. Our study confirmed that islet cells transfected with low doses of adenovirus could achieve high transfection efficiency, and would not affect the function of islet cells (P > 0.05). Splenocytes cultured with Ad-IκBα-IRES2-CD40L-transfected islets resulted in homospecific hyporesponsiveness. The islet graft MST (>100 d) in the Ad-IκBα-IRES2-sCD40L-treated group was dramatically prolonged compared with that in the nontreatment group (7.1 ± 1.16 d). In addition, TNF-α, IL-1ß, and IFN-γ were diminished in the Ad-IκBα-IRES2-sCD40L-treated group, which was commensurate with the reduced cellular infiltration (P < 0.01). Simultaneous blockade of the CD40/CD40L and IκB/NF-κB pathways could effectively extend the survival of islet grafts.

Tea polyphenol-induced neuron-like differentiation of mouse mesenchymal stem cells.

Bone marrow mesenchymal stem cells (BMSCs) can be induced to differentiate into neuron-like cells under appropriate conditions often involving toxic reagents that are not applicable for clinical transplantation. The present study investigated whether tea polyphenol (TP), a native nontoxic antioxidant, could induce mouse neuron-like cell differentiation of BMSCs in vitro. BMSCs, dissected from mouse femur bone marrow, were amplified in culture and treated with TP or beta-mercaptoethanol (BME, control). Morphological changes were observed under light microscopy. After 12 h treatment with 50 microg/ml TP or 5 mM BME, most cells differentiated into neuron-like cells exhibiting neuronal morphological characteristics, cellular shrinkage and neurite growth. Immunocytochemistry and reverse transcription (RT)-PCR results demonstrated neuronal marker expression in the induced cells with no glial fibrillary acidic protein expression. Taken together, TP induced mouse BMSCs to differentiate into neuron-like cells in vitro. These findings provide a potential source for the treatment of various neurological diseases.

Application of kushenin on patients with chronic hepatitis C after renal transplantation.

OBJECTIVE: To evaluate the efficacy of kushenin in treating patients with chronic hepatitis C after renal transplantation. METHODS: Fifty-five patients were randomly assigned by lottery to the treatment group (29 cases) and control group (26 cases). The same immunosuppression therapy was given to all patients in both groups. Patients in the treatment group were treated with kushenin 0.6 g once a day, while those in the control group were treated with conventional liver protective agents such as vitamins. The treatment duration of both groups was 3 months. The incidences of serious hepatitis and acute rejection reaction, serum biochemistry parameters including indicators of liver and kidney functions, hepatic fibrosis index, and serum HCV-RNA were compared between the two groups. RESULTS: (1) The incidence of serious hepatitis in the treatment group and the control group was 3.45% (1/29 cases) and 11.54% (3/26 cases), respectively, which was insignificantly different between the two groups (P=0.335). (2) The incidence of acute rejection in the treatment group was 6.90% (2/29 cases) and that in the control group was 7.69% (2/26 cases), showing insignificant difference (P=0.335). (3) The differences in serum alanine aminotransferase (ALT), direct bilirubin (DBIL), hyaluronic acid (HA), propeptide collagen type III (PC III), laminin (LN), collagen type IV (Col IV) levels between the two groups were insignificant before transplantation (P>0.05), while the above-mentioned parameters in the treatment group were significantly lower than those in the control group after transplantation (P<0.05). The difference in serum creatinine (SCr) and endogenous creatinine clearance rate (CCr) between the two groups was insignificant before and after transplantation (P>0.05). (4) The negative conversion rate of HCV-RNA in the treatment group was 31.03% (9/29 cases), significantly higher than the value of 11.54% (3/26 cases) in the control group after transplantation (P<0.05). (5) The levels of serum ALT and DBIL in patients with HCV-RNA converted to negative were significantly lower than those with still-positive HCV-RNA (P<0.05). CONCLUSIONS: Kushenin has a certain effect on inhibiting the proliferation of HCV, protecting liver cells, and anti-liver fibrosis. On the other hand, it has no obvious influence on renal allograft function. Thus, the drug is clinically safe and effective for use in treating patients with chronic hepatitis C after renal transplantation.

Polyglycolic Acid Fibrous Scaffold Improving Endothelial Cell Coating and Vascularization of Islet.

BACKGROUND: Improving islet graft revascularization has become a crucial task for prolonging islet graft survival. Endothelial cells (ECs) are the basis of new microvessels in an isolated islet, and EC coating has been demonstrated to improve the vascularization and survival of an islet. However, the traditional method of EC coating of islets has low efficiency in vitro. This study was conducted to evaluate the effect of a polyglycolic acid (PGA) scaffold on the efficiency of islet coating by ECs and the angiogenesis in the coated islet graft. METHODS: A PGA fibrous scaffold was used for EC coating of islet culture and was evaluated for its efficiency of EC coating on islets and islet graft angiogenesis. RESULTS: In in vitro experiments, we found that apoptosis index of ECs-coating islet in PGA group (27% ± 8%) was significantly lower than that in control group (83% ± 20%, P < 0.05) after 7 days culture. Stimulation index was significantly greater in the PGA group than in the control group at day 7 after ECs-coating (2.07 ± 0.31 vs. 1.80 ± 0.23, P < 0.05). vascular endothelial growth factor (VEGF) level in the PGA group was significantly higher than the coating in the control group after 7 days culture (52.10 ± 13.50 ng/ml vs. 16.30 ± 8.10 ng/ml, P < 0.05). Because of a tight, circumvallated, adhesive and three-dimensional growth microenvironment, islet cultured in a PGA scaffold had higher coating efficiency showing stronger staining intensity of enzyme than those in the control group after 14 days of culture following ECs-coating. For in vivo study, PGA scaffold significantly prolonged the average survival time of EC-coated islet graft after transplantation compared with control group (15.30 ± 5.60 days vs. 8.30 ± 2.45 days, P < 0.05). The angiogenesis and area of survived grafts were more in the PGA group compared with the control group by measuring the mean microvessel density (8.60 ± 1.21/mm2 vs. 5.20 ± 0.87/mm2, P < 0.05). In addition, expression of VEGF and tyrosin-protein kinase receptor (Tie-2) gene increased in PGA scaffold group than that in control group by real-time reverse transcription-polymerase chain reaction analysis. CONCLUSIONS: These results demonstrate that the efficiency of EC coating of islets was successfully increased by culturing ECs on a PGA scaffold. This method enhances the function, survival, and vascularization of isolated islets in vitro and in vivo.

Small intestinal submucosa improves islet survival and function during in vitro culture.

AIM: To evaluate the recovery and function of isolated rat pancreatic islets during in vitro culture with small intestinal submucosa (SIS). METHODS: Pancreatic islets were isolated from Wistar rats by standard surgical procurement followed by intraductal collagenase distension, mechanical dissociation and Euroficoll purification. Purified islets were cultured in plates coated with multilayer SIS (SIS-treated group) or without multilayer SIS (standard cultured group) for 7 and 14 d in standard islet culture media of RPMI 1640. After isolation and culture, islets from both experimental groups were stained with dithizone and counted. Recovery of islets was determined by the ratio of counts after the culture to the yield of islets immediately following islet isolation. Viability of islets after the culture was assessed by the glucose challenge test with low (2.7 mmol/L) and high glucose (16.7 mmol/L) solution supplemented with 50 mmol/L 3-isobutyl-1-methylxanthine (IBMX) solution. Apoptosis of islet cells after the culture was measured by relative quantification of histone-complexed DNA fragments using ELISA. RESULTS: After 7 or 14 d of in vitro tissue culture, the recovery of islets in SIS-treated group was significantly higher than that cultured in plates without SIS coating. The recovery of islets in SIS-treated group was about twice more than that of in the control group. In SIS-treated group, there was no significant difference in the recovery of islets between short- and long-term periods of culture (95.8+/-1.0% vs 90.8+/-1.5%, P>0.05). When incubated with high glucose (16.7 mmol/L) solution, insulin secretion in SIS-treated group showed a higher increase than that in control group after 14 d of culture (20.7+/-1.1 mU/L vs 11.8+/-1.1 mU/L, P<0.05). When islets were placed in high glucose solution containing IBMX, stimulated insulin secretion was higher in SIS-treated group than in control group. Calculated stimulation index of SIS-treated group was about 23 times of control group. In addition, the stimulation index of SIS-treated group remained constant regardless of short- and long-term periods of culture (9.5+/-0.2 vs 10.2+/-1.2, P>0.05). Much less apoptosis of islet cells occurred in SIS-treated group than in control group after the culture. CONCLUSION: Co-culture of isolated rat islets with native sheet-like SIS might build an extracellular matrix for islets and provide possible biotrophic and growth factors that promote the recovery and subsequent function of islets.

Isolation and culture of adult Sertoli cells and their effects on the function of co-cultured allogeneic islets in vitro.

BACKGROUND: Globally, 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. METHODS: Adult 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. RESULTS: In 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). CONCLUSIONS: A 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.

Effect of small intestinal submucosa on islet recovery and function in vitro culture.

BACKGROUND: The ability to maintain isolated human islet preparation in tissue culture has recently been adopted by most islet transplant centers to improve the safety and practicality of islet transplantation. However, maintaining islet viability and recovery remains a challenge in clinical setting. Extracellular matrix (ECM) is one of the most important components of islet microenvironment. The reconstruction of the cell-matrix relationship seems to be effective in improving the loss of differentiated islet structure and function. Small intestinal submucosa (SIS), a naturally occurring ECM, has been investigated to be able to promote wound healing, tissue remodeling, and cell growth. The purpose of this study was to evaluate the recovery and function of isolated rat pancreatic islets after in vitro culture with SIS. METHODS: Pancreatic islets were isolated from Wistar rats by using standard surgical procurement followed by intraductal collagenase distension, mechanical dissociation, and EuroFicoll purification. Groups of purified islets were cultured in plates which were coated with multilayer SIS (SIS-treated group) or without (standard cultured group) for 7 days and 14 days in standard islet culture conditions of RPMI 1640 tissue culture media in humidified atmosphere containing 95% air and 5% CO2 at 37 degree centigrade. The mean recovery of islets after the culture period was determined by sizing duplicate counts of a known volume and their viability was assessed by static incubation with low glucose (2.7 mmol), high glucose (16.7 mmol) and high glucose solution supplemented with 50 mum 3-isobutyl-1-methylxanthine (IBMX) solution. RESULTS: After 7 days and 14 days of in vitro tissue culture, the SIS-treated group showed a significantly higher recovery compared with those cultured under standard conditions. The recovery in the SIS-treated group was about two times of the control group cultured in standard conditions after 14 days culture. In the SIS-treated group, there was no statistically difference between the short and long periods of culture(95.8+/-1.0% vs. 90.8+/-1.5%, P>0.05). During incubation in high glucose (16.7 mmol) solution, there was a 2-3 fold increase in insulin secretion from both groups,but the SIS-treated group showed a higher increase than the standard cultured group after 14-day culture (20.7+/-1.1 mU/L vs. 11.8+/-1.1 mU/L, P<0.05). When islets were placed in the high glucose solution supplemented with IBMX, the stimulated insulin response in the SIS-treated group was higher than that in the standard cultured group in spite of the duration of the culture. The stimulation index of the SIS-treated group was about 2-3 times of the standard cultured group. In addition, after a long period of culture, the stimulation index of the SIS-treated group was statistically equivalent with that of the short period of culture (9.5+/-0.2 vs. 10.2+/-1.2, P>0.05). CONCLUSIONS: The co-culture of isolated rat islets with native sheet-like SIS can provide an excellent extracellular matrix, possible biotrophic and growth factors that promote the recovery and subsequent function of islets after in vitro tissue culture. In view of results of this study and rapid degradation of SIS in vitro, future studies will investigate the extended duration of culture and the effect of SIS on islets in vitro.

Treatment of cytomegalovirus infection after renal transplantation: experience from a single center in China.

BACKGROUND: We compared the efficacy and safety of 2 different treatments of CMV infection, including asymptomatic CMV replication and CMV disease. MATERIAL AND METHODS: 852 renal transplantation recipients, including asymptomatic CMV replication and CMV disease, received antiviral therapies of intravenous acyclovir or comprehensive anti-infection solution, mainly with intravenous ganciclovir. Effect, time, acute allograft rejection, and safety were analyzed during the antiviral therapy RESULTS: The total effective rates were higher with ganciclovir in both asymptomatic CMV replication (98.96% vs. 84.90%) and CMV disease (96.29% vs. 50.36%). Ganciclovir significantly shortened antiviral therapy duration in both asymptomatic CMV replication (15.0 ± 2.3 days vs. 16.0 ± 3.4 days) and CMV disease (19.7 ± 3.1 days vs. 21.5 ± 4.0 days). The acute allograft rejection incidences were significantly lower with ganciclovir in both asymptomatic CMV replication (8% vs. 14%) and CMV disease (11% vs. 22%). CMV-IEA was detected in renal grafts of patients with acute rejection. There was more CMV-associated acute rejection using acyclovir than using ganciclovir. Except for the higher incidence of anemia leucopenia and anemia with ganciclovir, the safety profiles of both drugs were similar. CONCLUSIONS: Comprehensive anti-infection solution, mainly with intravenous ganciclovir, can effectively treat CMV infection, shorten duration of therapy, and decrease acute rejection. The few adverse effects had negligible effects on use of ganciclovir.

[Comparison of different isolation methods on adult Sertoli cells co-transplanted with islets].

AIM: To establish a more convenient and effective method for isolating adult Sertoli cells and apply the method to islet transplantation. METHODS: Trypsin, DNase, collagenase and hyaluronidase were used for a one-step digestion in group A. A two-step digestion was used in group B, in which testis tissues were first digested by trypsin and DNase and then were digested by collagenase and hyaluronidase. In group C, trypsin and DNase were used in the first step of digestion, hyaluronidase was used in the second step and collagenase was used in the third step. Sertoli cells were identified by morphology and immunohistochemistry and the viability and purity of Sertoli cells were detected by MTT and flow cytometry (FCM). Expression of Fas-L was detected by Western blot and the effects of the co-transplantation of islets and Sertoli cells were compared between the three groups. RESULTS: Typical Sertoli cells were seen after isolation using the three different methods. Sertoli cells isolated by method A and method B were large in number while those isolated by method B and method C were pure. The results of MTT showed that the viability of Sertoli cells in group B was significantly higher than that in group A and group C (P<0.05) and Western blot results showed that expression of Fas-L on Sertoli cells in group B was significantly stronger than that in group A and group C (P<0.05). The purity of Sertoli cells detected by FCM in group B and group C were significantly higher than that in group A (P<0.05). The survival of islets co-transplanted with Sertoli cells to renal capsule of diabetic mice was significantly longer in group B compared with that in control group as well as in group A and group C (P<0.05). CONCLUSION: Sertoli cells obtained by the two-step digestion method are of higher purity and viability, which significantly prolong the survival of islet graft by co-transplantation.

Study on systemic immune tolerance induction in rat islet transplantation by intravenous infusion of Sertoli cells.

BACKGROUND: Sertoli cells are usually co-transplanted with pancreatic islets to induce local immune tolerance. In this report, we used infusion with Sertoli cells in islet transplantation to induce systemic immune tolerance and studied the mechanism of the tolerance induction. METHODS: Streptozotocin-induced diabetic rats were divided into four groups before islet transplantation: group A as control; group B with intravenous infusion of Sertoli cells; group C with Sertoli cell infusion and Fas ligand antibody treatment; and group D with Sertoli cell infusion and transforming growth factor-beta1 antibody treatment. The mean survival time (MST) and insulin expression of islet grafts were measured. The number of lymphocytes and the levels of cytokines in peripheral blood were also measured. RESULTS: Group B had the longest MST of islet allografts (41.6+/-4.20 days) followed by groups C, D, and A (P<0.05). Immunohistochemistry showed similar results with MST. The rats in group B had the least CD4 T cells (only 15.6%+/-6.4%) compared with other groups (P<0.05). The numbers of CD8 T cells in rats of groups B (11.2%+/-4.3%) and D (14.5%+/-5.6%) were significantly lower than those of groups A and C (P<0.05). After transplantation, group B's interleukin (IL)-2 level (1.92+/-0.68 ng/mL) was found to be significantly lower than that of other groups (P<0.05). Interferon-gamma showed similar pattern of change as IL-2 (P<0.05). Groups A and D had significantly lower levels of IL-4 (4.31+/-1.97 pg/mL 4.69+/-1.33 pg/mL, respectively) than groups B and C (P<0.05). CONCLUSION: Infusion of Sertoli cells could effectively prolong the survival of islet grafts and reduce peripheral blood lymphocyte and cytokine levels. In this process, transforming growth factor-beta1 played a major role and Fas ligand played a smaller additional role.

Allograft rejection-related gene expression in the endothelial cells of renal transplantation recipients after cytomegalovirus infection.

OBJECTIVE: To explore the effects of cytomegalovirus (CMV) infection on rejection-related gene expression in the endothelial cells of renal transplantation recipients. METHODS: Endothelial cells (ECs) were cultured and stimulated by a variety of factors: A, normal control group; B, inactivated human cytomegalovirus (HCMV) infection group; C, HCMV infection group; D, HCMV supernatant infection group; and E, ganciclovir HCMV group. Expression of intercellular adhesion molecule-1 (ICAM-1) and major histocompability complex (MHC) class I and class II antigens was detected by flow cytometry (FCM) and immunohistochemistry. RESULTS: We found characteristic CMV-infected ECs in this study. There were no significant differences among groups A, B and D (P>0.05). Although the expression levels of ICAM-1 were not significantly different between groups C and E (P>0.05), the ICAM-1 expression in these two groups was significantly higher than that in group A (P<0.05). ICAM-1 expression was detected in groups C and E, while there was no expression in groups A, B and D. Furthermore, there was no significant difference of ICAM-1 mRNA expression between groups C and E (P>0.05). Human leucocyte antigen (HLA)-ABC expression was detected in all the groups, while HLA-DR expression was only detected in groups C and E. There were no significant differences of HLA-ABC and HLA-DR expression among groups A, B and D (P>0.05). However, the HLA-ABC and HLA-DR expression levels in groups C and D were higher than those of the remaining groups previously reported (P<0.05). Meanwhile, the HLA-ABC and HLA-DR expression levels in group E were lower than those of group C (P<0.05). CONCLUSION: CMV could up-regulate the expression levels of ICAM-1 and MHC antigens, which was closely related to allograft rejection.

[Establishment of a rat islets model coated with human umbilical vein endothelial cells coexpressing sCD40L-Ig and CTLA4-Ig].

AIM: To isolate and culture primary human umbilical vein endothelial cells (HUVECs) and then to coat rat islets in vitro. METHODS: Primary HUVECs were isolated and cultured, then they were identified by detecting human VIII factor associated antigen with immunohistochemical method. Weible-palade bodies were observed by transmission electron microscope and the phagocytosis for DiI-Ac-LDL was detected by fluorescent microscopy. Rat islets were isolated and coated with HUVECs coexpressing sCD40L-Ig and CTLA4-Ig in a heparinized culture dish. The coated islets were observed via morphology and high glucose challenge test. RESULTS: The human VIII factor associated antigen, Weible-palade bodies and the phagocytosis for DiI-Ac-LDL were found in HUVECs. The islets coated by HUVECs coexpressing sCD40L-Ig and CTLA4-Ig were identified by green fluorescence proteins. Compared with that of the untreated islets (4.09), the release index of the coated islets was 3.94. There was no difference in insulin release between coated islets and untreated islets under glucose challenge. CONCLUSION: HUVECs have been isolated, cultured and identified successfully. The rat islets were coated with HUVECs in vitro function well.

[Recombinant adenovirus-mediated RNA silencing of tissue factor expression in human islet: an in vitro study].

OBJECTIVE: To construct a replication-incompetent recombinant adenovirus mediating short hairpin RNA (shRNA)-induced tissue factor gene silencing in the islet. METHODS: Four pairs of complementary oligonucleotides were designed and synthesized to create double-stranded oligonucleotides (ds oligo). The ds oligos were cloned into Pentr/U6 vector to construct the shuttle plasmid pENTR/U6-shRNA, which was transduced into human islets via liposome after sequence verification. The plasmid with the best silencing effect was identified by real-time RT-PCR, followed by homologous recombination with the adenovirus backbone plasmid. The functional clone was transfected into 293A cells to amplify the adenovirus, whose silencing effect against TF expression was tested using real-time RT-PCR and Western blotting. RESULTS: The pENTR/U6-shRNA shuttle plasmid was constructed and verified by sequencing. The recombinant adenovirus-mediated shRNA against TF was constructed, and real-time RT-PCR and Western blotting demonstrated that the strongest silencing effect of the adenovirus against TF occurred on the 4th day following islet transfection. CONCLUSION: Replication-incompetent recombinant adenovirus-mediated shRNA against TF has been successfully constructed, which has good silencing effect against TF expression in human islet in vitro.

[Cryopreservation of microencapsulated rat islets].

OBJECTIVE: To investigate the role of alginate-polylysine-alginate (APA) microcapsules in protecting rat islet cells in cryopreservation. METHOD: Purified rat islet cells microencapsulated with APA and free islet cells were cryopreserved for one month and then thawed for culture in RPMI 1640 overnight. The morphology of the cells was observed and their function assessed by stimulated insulin release test. RESULT: APA microcapsulation protected the fragile islets from freezing damage by increasing the recovery rate of the cells from 68.6%+/-2.9% to 94.7%+/-1.4% (P<0.05). After incubation with high glucose (16.7 mmol/L) solution, the insulin release from the encapsulated cells after cryopreservation significantly increased in comparison with that of the nonencapsulated cells (22.6+/-1.8 mU/L vs 11.7+/-1.5 mU/L, P<0.05). In high glucose solution containing theophylline, the calculated stimulation index of the encapsulated cells was about 3 times that of the nonencapsulated cells. CONCLUSION: APA microencapsulation may significantly increase the post-thaw recovery and improve the function for cryopreserved rat islets.

[Co-culture of cryopreserved rat islets with small intestinal submucosa].

OBJECTIVE: To investigate the feasibility and benefits of co-culture of cryopreserved islets with small intestinal submucosa (SIS). METHODS: Purified rat islets cryopreserved for one month were divided into SIS group and control group, and after culture in standard islet culture media RPMI1640 for 1 week, the morphology and function of the islets were assessed. RESULTS: The SIS protects the fragile islets from damage by cryopreservation, and increased the recovery from (60.6-/+3.3)% to (91.7-/+1.8) % (P<0.05). Compared with the control group, incubation of the islets of the SIS group in high-glucose (16.7 mmol/L) solution resulted in significantly enhanced insulin secretion (23.7-/+1.6 vs 12.5-/+1.1 mU/L, P<0.05). When the islets were incubated in high-glucose solution containing theophylline, the calculated stimulation index of SIS group was about 3-fold higher than that of the control group. CONCLUSION: Co-culture of cryopreserved rat islets with SIS can increase the recovery of islet cells and improve their function.

[Recombinant adenovirus-mediated human cytosolic glutathione peroxidase gene transfection protects vascular endothelial cells from oxidative damage].

OBJECTIVE: To study the protective effect of recombinant adenovirus-mediated human cytosolic glutathione peroxidase (hCGPx) gene transfection on vascular endothelial cells ECV304 from oxidative damage. METHODS: pGEM-T Easy Vector containing hCGPx cDNA and recombinant adenovirus shuttle plasmid pACCMV-pLpA were used to construct the shuttle plasmid pACCMV-hCGPx for cotransfection of 293 cells with pJM17, thereby to obtain the recombinant adenovirus AdCMV-hCGPx. Cultured ECV304 cells were transfected with AdCMV-hCGPx for 24, 48 and 72 h, respectively, with the cells transfected with the empty vector serving as control, and hCGPx gene expression was then examined in the transfected cells. The transfected cell viability and apoptotic cell ratio were evaluated after treatment of the cells with H(2)O(2). RESULTS: The expression ratio of hCGPx gene was significantly higher in the AdCMV-hCGPx-transfected cells than in those with empty vector transfection (P<0.01). The hCGPx gene-transfected cells showed significantly higher viability and significantly lower apoptotic ratio than the control cells following challenge with H(2)O(2)-induced oxidative damage. CONCLUSION: hCGPx gene transfer mediated by recombinant adenovirus protects the vascular endothelial cells from oxidative damage in vitro, possibly due to the antioxidative and apoptosis-inhibiting effect of hCGPx.

[The isolation and culture of Sertoli cells from adult testis and their immune privilege mechanism].

AIM: To set up a method of isolation and culture of Sertoli cells from adult testis and to investigate their immune privilege mechanism. METHODS: Adult testis Sertoli cells were prepared successfully by digestion with trypsin, collagenase, hyaluronidase and DNase, and then the expression of Fas-L and TGF-beta1 was examined by SABC staining. The Sertoli cells were cocultured with adult splenocytes to detect the inhibitory effect of Sertoli cells on splenocyte proliferation by MTT colorimetry. RESULTS: In cultured cells, Sertoli cells accounted for more than 80% of total cells. The activity of Sertoli cells reached 90%. Sertoli cells expressed Fas-L and TGF-beta1 and could inhibit the proliferation of cocultured splenocytes in vitro. CONCLUSION: A method of isolation and culture of Sertoli cells from adult testis has been established. The immune privilege mechanism of Sertoli cells may be related to the expression of Fas-L and TGF-beta1.