| 1. |
- Bohman, Sara, et al.
(författare)
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Transient beneficial effect of Exendin-4 treatment on the function of microencapsulated mouse pancreatic islets
- 2007
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 16:1, s. 15-22
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Tidskriftsartikel (refereegranskat)abstract
- Transplantation of microencapsulated islets may reduce hyperglycemia in the absence of immunosuppression. However, the efficiency of microencapsulated islet transplantation is low, requiring more islets to achieve normoglycemia than in vascularized islet transplantation. Exendin-4 (a glucagon-like receptor agonist) has been previously shown to improve islet transplantation outcome in rodents. We investigated whether this treatment would enhance the function of microencapsulated islets in vitro and in vivo. Encapsulated or naked islets were cultured with or without exendin-4 for 72 h. To test in vitro function, insulin release and glucose oxidation rates were measured in the absence or presence of exendin-4. In addition, in vivo function of a minimal mass of 350 microencapsulated islets was assessed by syngeneic transplantation into the peritoneal cavity of alloxan-diabetic mice. Glucose oxidation rates of microencapsulated islets were improved by 72-h pretreatment with exendin-4. Insulin release was increased both acutely after glucose stimulation and over a 40-h culture period by the presence of exendin-4. Transplantation outcome of microencapsulated islets cultured with exendin-4 was initially improved, but by day 7 there were no differences compared with control cultured microencapsulated islets. Culture of microencapsulated islets with exendin-4 increases glucose oxidation and insulin release rates, but the increased function seen in vitro was not enough to improve the long term outcome in a transplantation model.
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| 2. |
- Brandhorst, Daniel, et al.
(författare)
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Porcine islet graft function is affected by pretreatment with a caspase-3 inhibitor
- 2006
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 15:4, s. 311-317
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Tidskriftsartikel (refereegranskat)abstract
- During the isolation procedure and after transplantation islets are subjected to numerous variables associated with the induction of apoptosis. The present study investigated the effect of transient pretreatment with caspase inhibitors on function and survival of transplanted pig islets. Isolated porcine islets (3000 IEQ) were incubated overnight in 200 mu M of the caspase-3 inhibitor DEVD-CMK prior to transplantation into diabetic nude mice. Glucose-stimulated insulin release of pretreated islets was assessed during static incubation. DEVD-CMK successfully prevented the expression of capase-3 and DFF as demonstrated in heat-shocked pig islets. Nevertheless, transient pretreatment of freshly isolated pig islets with DEVD-CMK resulted in a significantly decreased final graft function of 50.0% (n = 16) compared to 85.7% (n = 14) in control islets (p < 0.05). Glucose-stimulated insulin release of porcine islets (n = 6) was not significantly effected by overnight culture with DEVD-CMK. Morphological assessment revealed that this caspase-3 inhibitor significantly increased the percentage of necrosis to a small, but nevertheless significant, extent in comparison to control islets (p < 0.05). The study demonstrates that short-time pretreatment with the caspase-3 inhibitor DEVD-CMK reduces the capacity of transplanted porcine islets to restore normoglycemia in diabetic nude mice.
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| 3. |
- Brandhorst, Heide, 1962-, et al.
(författare)
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Effect of pretransplant preconditioning by whole body hyperthermia on islet graft survival
- 2007
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 16:7, s. 707-715
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Tidskriftsartikel (refereegranskat)abstract
- Previous observations in heat-shocked pig islets revealed the ambivalent character of the stress response simultaneously inducing processes of protection and apoptosis. To clarify whether the proapoptotic character of the stress response is reduced in heat-exposed islets still embedded in their native environment, hyperthermia was performed in the present study either as whole body hyperthermia (WBH) prior to pancreas resection or as in vitro heat shock (HS) after isolation. HS (42 degrees C/45 min) was induced in donors 12 h before isolation (WBH, n = 32) or in freshly isolated islets prior to 12 h of culture at 37 degrees C (in vitro HS, n = 25). Islets continuously incubated at 37 degrees C served as controls (n = 34). Proinflammatory treatment was performed with H2O2, DETA-NO, or a combination of IL-1beta, TNF-alpha, and IFN-gamma. Quality assessment included islet yield, viability staining, static glucose incubation, and nude mouse transplantation. WBH was significantly less effective than in vitro HS to induce HSP70 overexpression and to increase islet resistance against inflammatory mediators. Although characterized by an unaltered Bax to Bcl-2 ratio, islets subjected to WBH partially failed to restore sustained normoglycemia in diabetic nude mice. The inflammatory response observed in the pancreas of WBH-treated rats was associated with significantly reduced viability that seems to have a higher predictive value for posttransplant outcome compared to islet in vitro function or mitochondrial activity. In contrast, in vitro HS significantly decreased transcript levels of Bcl-2, but did not affect posttransplant function compared to sham-treated islets. These findings suggest that WBH is primarily associated with increased necrosis as a secondary tissue type-specific effect of pancreas damage while in vitro HS mainly induces apoptosis.
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| 4. |
- Börjesson, Andreas, et al.
(författare)
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Survival of an islet allograft deficient in iNOS after implantation into diabetic NOD mice
- 2006
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 15:8-9, s. 769-775
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Tidskriftsartikel (refereegranskat)abstract
- Proinflammatory cytokines play a major role in rejection of pancreatic islet allografts and in type 1 diabetes (T1D). In rodent islets, exposure to IL-1β alone or combined with IFN-γ induces expression of inducible nitric oxide synthase (iNOS). Inhibition of iNOS or a deletion of the iNOS gene has been shown to be protective in animal models of T1D. In the present study we tested the hypothesis that transplantation of pancreatic islets deficient in iNOS (iNOS-/-) would permit increased graft survival. Pancreatic islets isolated from wild-type (wt) mice and iNOS-/- mice were allogeneically transplanted beneath the kidney capsule of spontaneously diabetic NOD mice. When blood glucose increased above 12.0 mM after preceding normalization of hyperglycemia, animals were sacrificed. Histological examinations of grafts were performed and graft gene expression was analyzed by real-time PCR. Transplantations of the two types of islets could reverse hyperglycemia and the grafts functioned for on average 1 week posttransplantation. Morphological examination of both types of islet grafts showed immune cell infiltration around and within the grafts. Remaining endocrine cells could be observed in wt and iNOS-/- islet grafts. In the removed grafts iNOS-/- islet tissue contained higher mRNA levels of insulin, proinsulin convertases (PC-1 and PC-2), and IL-1β compared to transplanted wt islets. The assessments of insulin, PC-1 and PC-2 mRNAs of the grafts suggest that the iNOS-/- islets may be more resistant to destruction in the transplantation model used; however, this was not sufficient to prolong the period of normoglycemia posttransplantation.
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| 5. |
- Cabrera, O, et al.
(författare)
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Automated, High-Throughput Assays for Evaluation of Human Pancreatic Islet Function
- 2007
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Ingår i: Cell transplantation. - : SAGE Publications. - 1555-3892 .- 0963-6897. ; 16:10, s. 1039-1048
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Tidskriftsartikel (refereegranskat)abstract
- An important challenge in pancreatic islet transplantation in association with type 1 diabetes is to define automatic high-throughput assays for evaluation of human islet function. The physiological techniques presently used are amenable to small-scale experimental samples and produce descriptive results. The postgenomic era provides an opportunity to analyze biological processes on a larger scale, but the transition to high-throughput technologies is still a challenge. As a first step to implement high-throughput assays for the study of human islet function, we have developed two methodologies: multiple automated perifusion to determine islet hormone secretion and high-throughput kinetic imaging to examine islet cellular responses. Both technologies use fully automated devices that allow performing simultaneous experiments on multiple islet preparations. Our results illustrate that these technologies can be applied to study the functional status and explore the pharmacological profiles of islet cells. These methodologies will enable functional characterization of human islet preparations before transplantation and thereby provide the basis for the establishment of predictive tests for β-cell potency.
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| 6. |
- Cabric, Sanja, et al.
(författare)
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Adenovirus-Mediated Expression of the Anticoagulant Hirudin in Human Islets : A Tool to Make the Islets Biocompatible to Blood
- 2006
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 15:8-9, s. 759-767
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Tidskriftsartikel (refereegranskat)abstract
- Human islets induce an injurious clotting reaction at the time of transplantation. A potential strategy to counteract this reaction would be to allow the islets to express hirudin, a protein with direct anticoagulative activity. Human islets were transduced with an adenoviral vector encoding hirudin, an empty corresponding vector, or left untreated. Islet culture supernatants were analyzed for hirudin using an ELISA, a chromogenic substrate assay based on the thrombin-binding properties of hirudin and in a whole blood viscosimetry assay. Immunohistochemical evaluation and determination of hirudin content revealed an abundant expression of hirudin after transduction. Hirudin content in transduced islets was in the range of the insulin content levels. A delay in human whole blood clotting time could be observed after addition of supernatants taken from islet cultures expressing hirudin. However, transduced islets showed an impaired glucose-stimulated insulin release, but could readily be retrieved 6 weeks after transplantation to athymic mice. A marked expression and secretion of hirudin with functional capacity can be induced in human islets using an adenoviral vector. The impairment in glucose-stimulated insulin release in hirudin-secreting islets, compared to controls, indicates that the additional protein synthesis affects the functional capacity of the islets.
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| 7. |
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| 8. |
- Estrada, EJ, et al.
(författare)
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Combined treatment of intrapancreatic autologous bone marrow stem cells and hyperbaric oxygen in type 2 diabetes mellitus
- 2008
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Ingår i: Cell transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 17:12, s. 1295-1304
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to determine whether the combination therapy of intrapancreatic autologous stem cell infusion (ASC) and hyperbaric oxygen treatment (HBO) before and after ASC can improve islet function and metabolic control in patients with type 2 diabetes mellitus (T2DM). This prospective phase 1 study enrolled 25 patients with T2DM who received a combination therapy of intrapancreatic ASC and periinfusion HBO between March 2004 and October 2006 at Stem Cells Argentina Medical Center Buenos Aires, Argentina. Clinical variables (body mass index, oral hypoglycemic drugs, insulin requirement) and metabolic variables (fasting plasma glucose, C-peptide, HbA1c, and calculation of C-peptide/glucose ratio) were assessed over quartile periods starting at baseline and up to 1 year follow-up after intervention. Means were calculated in each quartile period and compared to baseline. Seventeen male and eight female patients were enrolled. Baseline variables expressed as means ± SEs were: age 55 ± 2.14 years, diabetes duration 13.2 ± 1.62 years, insulin dose 34.8 ± 2.96 U/day, and BMI 27.11 ± 0.51. All metabolic variables showed significant improvement when comparing baseline to 12 months follow-up, respectively: fasting glucose 205.6 ± 5.9 versus 105.2 ± 14.2 mg/dl, HbA1c 8.8 ± 0.2 versus 6.0 ± 0.4%, fasting C-peptide 1.5 ± 0.2 versus 3.3 ± 0.3 ng/ml, C-peptide/glucose ratio 0.7 ± 0.2 versus 3.5 ± 0.3, and insulin requirements 34.8 ± 2.9 versus 2.5 ± 6.7 U/day. BMI remained constant over the 1-year follow-up. Combined therapy of intrapancreatic ASC infusion and HBO can improve metabolic control and reduce insulin requirements in patients with T2DM. Further randomized controlled clinical trials will be required to confirm these findings.
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| 9. |
- Fort, A, et al.
(författare)
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Biohybrid devices and encapsulation technologies for engineering a bioartificial pancreas
- 2008
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Ingår i: Cell transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 17:9, s. 997-1003
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Tidskriftsartikel (refereegranskat)abstract
- The use of cell-based treatments in the field of metabolic organs, particularly the pancreas, has seen tremendous growth in recent years. The transplantation of islet of Langerhans cells for the treatment of type 1 diabetes mellitus (T1DM) has allowed for natural glycemic control for patients plagued with hypoglycemia unawareness. The transplantation of islet cells into the portal vein of the liver, however, has presented challenges to the survival of the cells due to inflammation, vascularization, the need for systemic immunosuppression, and physical stress on the graft. New advances in the engineering of appropriate biohybrid devices and encapsulation technologies have led to promising alternatives to traditional methods.
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| 10. |
- Friberg, Andrew S., et al.
(författare)
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Human islet separation utilizing a closed automated purification system
- 2008
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 17:12, s. 1305-1313
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Tidskriftsartikel (refereegranskat)abstract
- A central step within the human islet isolation process is the separation of islets from contaminating exocrine tissue utilizing linear, continuous density gradients manufactured by means of manually controlled standard gradient makers (SGM). The present study was performed to develop a closed, automated purification system (APS) that customizes density gradient profiles aiming to standardize and optimize human islet purification. Digested human pancreata were pooled, split evenly, and incubated in UW solution according to our standard protocol (n = 11). Continuous density gradient centrifugation was performed in parallel in two refrigerated COBE 2991 cell separators loaded with light (1.076 g/ml) and heavy (1.097 g/ml) Ficoll utilizing either an SGM or two computer-controlled pumps connected to Ficoll-containing bags. Quality control included islet equivalent (IE) yield, purity, in vitro function, and islet cytokine expression. Gradient profiles demonstrated that the APS readily customizes linear and nonlinear gradients. In comparison to the SGM, the APS recovered a higher percentage of the expected volume of continuous gradients (90.0 +/- 1.1% vs. 98.2 +/- 2.0%, p < 0.05). Islet yield (120,468 +/- 15,970 vs. 114,570 +/- 15,313 IE, NS) and purity (51.7 +/- 4.8% vs. 54.4 +/- 4.9%, NS) were nearly identical utilizing the SGM or APS. Decreased MCP-1, IL-6, and IL-8 expression indicated that APS-purified islets were possibly exposed to less proinflammatory stress. Compared to standard procedures, similar success and gentle continuous density gradient separation of human islets is feasible utilizing the APS. The APS facilitates the standardization of this complex procedure according to cGMP standards.
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| 11. |
- Iken, M., et al.
(författare)
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Pig Pancreas Oxygenation at 20°C Increases Islet ATP Generation but Deteriorates Islet Function
- 2009
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 18:7, s. 745-751
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Tidskriftsartikel (refereegranskat)abstract
- Successful pancreas preservation during storage in oxygenated perfluorodecalin (PFD) is mainly related to oxidative ATP generation during storage. Increasing the storage temperature would accelerate this process essential for resuscitation of ischemically damaged pancreatic tissue. The present study aimed at comparing islet isolation outcome from adult pig pancreata preserved in oxygenated PFD by means of a one-layer method during storage on ice or at 20 degrees C. Resected pancreata were intraductally flushed with cold UW solution and promptly processed (n = 6) or stored for 3 h in continuously oxygenated PFD at 4 degrees C (n = 5) or 20 degrees C (n = 7). Prior to digestion-filtration pancreata were intraductally injected with UW supplemented with Serva collagenase NB8 and neutral protease. Islet quality assessment determined viability, glucose stimulation index, mitochondrial activity, intracellular ATP content, and transplant function in diabetic nude mice. Pancreata oxygenated for 3 h at 20 degrees C yielded islet numbers similar to organs oxygenated at 4 degrees C. Compared to a storage temperature of 20 degrees C, preservation at 4 degrees C reduced islet ATP content (p < 0.05) as well as islet viability (p < 0.05). Nevertheless, PFD storage at 20 degrees C decreased insulin response to glucose compared to unstored pancreata (p < 0.05). In contrast to unstored pancreata or cold-stored organs, transplantation of islets isolated after oxygenation at 20 degrees C was characterized by an early loss of transplant function in 50% of recipients (p < 0.05). The present study demonstrates that PFD storage at 20 degrees C enhances islet ATP synthesis within a short period of oxygenation but deteriorates islet function. We conclude that the present data reflect an equilibration between reduced depression of metabolic activity resulting in damage of islets and temperature-stimulated acceleration of ATP synthesis. Future studies are required to adjust the optimum storage temperature for pancreas oxygenation in different species.
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| 12. |
- Johansson, Åsa, et al.
(författare)
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Inhibition of p38 MAP kinase in the early posttransplantation phase redistributes blood vessels from the surrounding stroma into the transplanted endocrine tissue
- 2006
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 15:6, s. 483-488
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Tidskriftsartikel (refereegranskat)abstract
- Transplanted pancreatic islets attain a chronically decreased vascular density following transplantation, despite the increased concentrations of vascular endothelial growth factor (VEGF) secreted from beta-cells in response to hypoxia during culture and in the immediate posttransplantation phase. VEGF, however, exerts dual effects on endothelial cells, and in islet endothelial cells of the adult, the vascular permeability-inducing effects of VEGF seem normally more pronounced than those to induce angiogenesis. p38 MAP kinase activity has recently been shown to serve as a switch to separate these properties of VEGF; inhibition of p38 MAP kinase activity enhances VEGF-induced angiogenesis and, at the same time, abrogates VEGF-induced vascular permeability. We hypothesized that the revascularization of transplanted islets may be hampered by a predisposition of adult islet endothelial cells to react to VEGF by forming fenestrae rather than migrating and proliferating. We therefore administered the p38 MAP kinase inhibitor SB203580 by daily IP injections for the first 14 days following transplantation, and then studied the influence of this treatment on the oxygen tension, blood perfusion, and vascular density of the islet grafts I month posttransplantation. SB203580 treatment redistributed islet graft blood vessels from the stroma into the endocrine tissue, and this redistribution of blood vessels into the endocrine tissue was accompanied by an increased oxygenation of the islet cells. However, the total number of blood vessels in the tissue was not affected. The blood perfusion of the islet grafts was also similar in control and SB203580-treated animals. Our results suggest that effects of VEGF to preferentially induce vascular permeability may partially contribute to, but is not the main cause of, low revascularization of transplanted islets.
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| 13. |
- Lau, Joey, et al.
(författare)
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Beneficial role of pancreatic microenvironment for angiogenesis in transplanted pancreatic islets
- 2009
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 18:1, s. 23-30
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic islets implanted heterotopically (i.e., into the kidney, spleen, or liver) become poorly revascularized following transplantation. We hypothesized that islets implanted into the pancreas Would become better revascularized. Islets isolated from transgenic mice expressing enhanced yellow fluorescent protein (EYFP) in all somatic cells were Cultured before they were implanted into the pancreas or beneath the renal capsule of athymic mice. Vascular density was evaluated in histological sections 1 month posttransplantation. EYFP was used as reporter for the transgene to identify the transplanted islets. Islet endothelial cells were visualized by staining with the lectin Bandeiraea simplicifolia (BS-1). Capillary numbers in intrapancreatically implanted islets were only slightly lower than those counted in endogenous islets, whereas islets implanted beneath the renal capsule had a markedly lower vascular density. In order to determine if this high graft vascular density at the intrapancreatic site reflected expansion of remnant donor endothelial cells or increased ingrowth of blood vessels from the host. also islets from Tie2-green fluorescent protein (GFP) mice (i.e., islets with fluorescent endothelial cells) were transplanted into the pancreas or beneath the renal capsule of athymic mice. These islet grafts revealed that the new vascular structures formed in the islet grafts contained very few GFP-positive cells, and thus mainly were of recipient origin. The reason(s) for the much better ingrowth of blood vessels at the intrapancreatic site merits further studies, because this may help us form strategies to overcome the barrier for ingrowth of host vessels also into islets in heterotopic implantation sites.
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| 14. |
- Nolan, K, et al.
(författare)
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Tissue engineering and biomaterials in regenerative medicine
- 2008
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Ingår i: Cell transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 17:3, s. 241-243
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Tidskriftsartikel (refereegranskat)abstract
- The field of regenerative medicine offers the potential to significantly impact a wide spectrum of healthcare issues, from diabetes to cardiovascular disease. In particular, the design of tailored biomaterials, which possess properties desired for their particular application, and the development of superior implant environments, which seek to meet the nutritional needs of the tissue, have yielded promising tissue engineering prototypes. In this commentary, we examine the novel approaches researchers have made in customized biomaterials and promoting angiogenesis that have led to significant advancements in recent years.
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| 15. |
- Strom, SC, et al.
(författare)
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Hepatocyte transplantation: clinical experience and potential for future use
- 2006
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Ingår i: Cell transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 1515 Suppl 1, s. S105-S110
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Tidskriftsartikel (refereegranskat)abstract
- Hepatocyte transplantation has been proposed as a method to support patients with liver insufficiency. There are three main areas where the transplantation of isolated hepatocytes has been proposed and used for clinical therapy. Cell transplantation has been used: 1) for temporary metabolic support of patients in end-stage liver failure awaiting whole organ transplantation, 2) as a method to support liver function and facilitate regeneration of the native liver in cases of fulminant hepatic failure, and 3) in a manner similar to gene therapy, as a “cellular therapy” for patients with genetic defects in vital liver functions. We will briefly review the basic research that leads to clinical hepatocyte transplantation, the published clinical experience with this experimental technique, and some possible future uses of hepatocyte transplantation.
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| 16. |
- Sumitran-Holgersson, S, et al.
(författare)
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Generation of hepatocyte-like cells from in vitro transdifferentiated human fetal pancreas
- 2009
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Ingår i: Cell transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 18:2, s. 183-193
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Tidskriftsartikel (refereegranskat)abstract
- Although the appearance of hepatic foci in the pancreas has been described in animal experiments and in human pathology, evidence for the conversion of human pancreatic cells to liver cells is still lacking. We therefore investigated the developmental plasticity between human embryonic pancreatic cells and liver cells. Cells were isolated and expanded from 7–8-week-old human fetal pancreata (HFP) and were characterized for the absence and presence of pancreatic and hepatic markers. In vitro expanded HFP were treated with fibroblast growth factor 2 (FGF2) and dexamethasone (DX) to induce a liver phenotye in the cells. These treated cells in various passages were further studied for their capacity to be functional in hepatic parenchyma following retrorsine-induced injury in nude C57 black mice. Amylase- and EPCAM-positive-enriched cells isolated from HFP and treated with FGF2 and DX lost expression of pancreatic markers and gained a liver phenotype. Hepatic differentiation was based on the expression (both at the mRNA and protein level) of liver markers albumin and cytokeratin 19. When transplanted in vivo into nude mice treated with retrorsine, both cell types successfully engrafted and functionally differentiated into hepatic cells expressing human albumin, glycogen, dipeptidyl peptidase, and γ-glutamyltranspeptidase. These data indicate that human fetal pancreatic cells have a capacity to alter their gene expression profile in response to exogenous treatment with FGF2 and DX. It may be possible to generate an unlimited supply of hepatocytes in vitro for cell therapy.
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| 17. |
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| 18. |
- von Seth, Erik, et al.
(författare)
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Distribution of intraportally implanted microspheres and fluorescent islets in mice
- 2007
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 16:6, s. 621-627
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to evaluate the distribution of intraportally transplanted islets in mice. We initially administered 2000 polystyrene microspheres with a diameter of 50 microm intraportally into normoglycemic C57BL/6 mice. In separate experiments other mice were injected similarly with 300 microspheres each with a diameter of 100 or 200 microm. One week later the animals were killed, and the lungs and livers were removed and divided into lobes. The number of microspheres in each individual liver lobe and in the lungs was counted using a stereomicroscope. In other experiments, athymic C57BL/6 mice were similarly implanted with 250 islets isolated from transgenic mice expressing the enhanced yellow fluorescent protein in the islet cells. The distribution of microspheres and islets was independent of size, and fairly homogenous within the liver, with the exception of the caudate lobe, which contained fewer microspheres and islets, respectively. Approximately one third of all microspheres and islets were present as aggregates. Eighty-five to 90% of the implanted microspheres were identified in the liver sections, whereas 60-65% of the implanted islets were recovered. Aggregates or single fluorescent cells were observed in the liver of islet-implanted mice. We conclude that islets and microspheres implanted into the liver distribute fairly homogenously and quite a few of them exist as aggregates or, with respect to islets, as fragments.
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| 19. |
- Yin, ZH, et al.
(författare)
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Isolation of mouse hepatocytes for transplantation: a comparison between antegrade and retrograde liver perfusion
- 2007
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Ingår i: Cell transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 16:8, s. 859-865
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Tidskriftsartikel (refereegranskat)abstract
- We compared antegrade with retrograde liver perfusion when isolating mouse hepatocytes for hepatocyte transplantation. Male mouse hepatocytes were isolated by different perfusion methods and transplanted into the spleen of congeneic female mice. Retrograde perfusion yielded a larger number of cells (4.90 × 107) than antegrade (4.09 × 107, p < 0.05), but hepatocytes obtained by antegrade perfusion gave higher engraftment efficiency (p < 0.05). More of the transplanted hepatocytes could be recovered from recipient liver with antegrade perfusion than with retrograde perfusion (p < 0.05). Our results indicate that hepatocytes isolated by antegrade perfusion gave a higher engraftment efficiency.
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| 20. |
- Åkesson, Elisabet, et al.
(författare)
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Long-term survival, robust neuronal differentiation, and extensive migration of human forebrain stem/progenitor cells transplanted to the adult rat dorsal root ganglion cavity
- 2008
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 17:10-11, s. 1115-1123
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Tidskriftsartikel (refereegranskat)abstract
- Neurons in dorsal root ganglia (DRGs) transmit sensory information from peripheral tissues to the spinal cord. This pathway can be interrupted, for example, as the result of physical violence, traffic accidents, or complications during child delivery. As a consequence, the patient permanently loses sensation and often develops intractable neuropathic pain in the denervated area. Here we investigate whether human neural stem/progenitor cells (hNSPCs) transplanted to the DRG cavity can serve as a source for repairing lost peripheral sensory connections. We found that hNSPCs robustly differentiate to neurons, which survive long-term transplantation. The neuronal population in the transplants was tightly surrounded by astrocytes, suggesting their active role in neuron survival. Furthermore, 3 months after grafting hNSPCs were found in the dorsal root transitional zone (DRTZ) and within the spinal cord. The level of differentiation of transplanted cells was high in the core of the transplants whereas cells that migrated to the DRTZ and spinal cord were undifferentiated, nestin-expressing precursors. These data indicate that peripherally transplanted hNPSCs can be used for repair of dorsal root avulsion or spinal cord injuries; however, additional factors are required to guide their differentiation to the desired type of neurons. Furthermore, hNPSCs that migrate from the DRG cavity graft site to the DRTZ and spinal cord may provide trophic support for regenerating dorsal root axons, thereby allowing them to reenter the host spinal cord.
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| 21. |
- Engelsberg, Karl, et al.
(författare)
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Transplantation of cultured adult porcine full-thickness retina.
- 2007
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Ingår i: Cell Transplantation. - 1555-3892. ; 16:1, s. 31-39
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Tidskriftsartikel (refereegranskat)abstract
- In this study we wanted to examine how an adult neuroretina from an animal with an eye similar to the human one survives in vitro. We also wanted to investigate how the culture process affects the adult retina when used in a transplantation paradigm. Full-thickness neuroretinal sheets from adult porcine eyes were dissected into pieces measuring 3 mm in diameter. These were kept in culture for 1-3 days. After this time, the explants were fixed or transplanted subretinally to adult pigs, which were killed after 72-74 days. Transplanted eyes, as well as tissue kept in culture only, were processed for hematoxylin and eosin staining and immunohistochemistry. Explants kept I day in vitro (DIV) displayed the normal morphology. In these specimens, single pyknotic cells were evident in the outer nuclear layer (ONL) and ganglion cell layer, but were more frequent in the inner nuclear layer (INL). After longer times in vitro, severe degenerative changes appeared. Transplanted explants kept I DIV prior to transplantation exhibited normal retina] lamination in two out of four specimens. Transducin and recoverin labeling revealed photoreceptors with inner segments in these grafts. Rod bipolar cells displayed a normal morphology. Vertically arranged Muller cells were also seen in the laminated grafts. Two of the three transplants kept 2 DIV displayed minimal lamination. Eyes with transplants kept 3 DIV prior to transplantation displayed degenerated grafts in all eyes. This study shows that adult porcine neuroretinal explants kept in culture for I day display a normal morphology in their major part. Additionally, 1-day explants can survive transplantation with retained morphology even after several months. This indicates the possibility of storing adult donor tissue between harvest and transplantation. The culture system may also be used in the future as a tool for manipulating retina] donor tissue prior to transplantation.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
- Tallheden, Tommi, 1972, et al.
(författare)
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Human serum for culture of articular chondrocytes.
- 2005
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Ingår i: Cell transplantation. - 0963-6897. ; 14:7, s. 469-79
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Tidskriftsartikel (refereegranskat)abstract
- In the field of cell and tissue engineering, culture expansion of human cells in monolayer plays an important part. Traditionally, cell cultures have been supplemented with serum to support attachment and proliferation, but serum is a potential source of foreign protein contamination and viral protein transmission. In this study, we evaluated the use of human serum for experimental human articular chondrocyte expansion and to develop a method for preparation of large volumes of high-quality human serum from healthy blood donors. Human autologous serum contained high levels of epidermal-derived growth factor and platelet-derived growth factor-AB and supported proliferation up to 7 times higher than FCS in primary chondrocyte cultures. By letting the coagulation take place in a commercially available transfusion bag overnight, up to 250 ml of growth factor-rich human serum could be obtained from one donor. The allogenic human serum supported high proliferation rate without losing expression of cartilage-specific genes. The expanded chondrocytes were able to redifferentiate and form cartilage matrix in comparable amounts to autologous serums. In conclusion, the transfusion bags allow preparation of large volumes of growth factor-rich human serum with the capacity to support in vitro cell expansion. The data further indicate that by controlling the coagulation process there are possibilities of optimizing the release of growth factors for other emerging cell therapies.
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| 31. |
- Warfvinge, Karin, et al.
(författare)
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Retinal progenitor cell xenografts to the pig retina: immunological reactions.
- 2006
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Ingår i: Cell Transplantation. - 1555-3892. ; 15:7, s. 603-612
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated the host response to murine retinal progenitor cells (RPCs) following transplantation to the subretinal space (SRS) of the pig. RPCs from GFP mice were transplanted subretinally in 18 nonimmunosuppressed normal or laser-treated pigs. Evaluation of the SRS was performed on hematoxylin-cosin (H&E)-stained sections. Serum samples were taken from naive and RPC-grafted pigs and mouse-reactive antibody responses were assessed. At 1 week, histology showed a few perivascular lymphocytes consistent with a mild retinal vasculitis, and depigmentation of the RPE with large numbers of mononuclear inflammatory cells in the choroid near the transplantation site. Large choroidal infiltrates were evident at 2-5 weeks. Serum from naive and RPC-xenografted pigs contained significant levels of preformed IgG and IgM antibodies against murine antigens. Xenogeneic RPCs transplanted to the porcine SRS induced mononuclear infiltration in the choroid with graft rejection occurring over 2-5 weeks. Serum analysis confirmed that mice and pigs are discordant species; however, a cell-mediated acute mechanism appears to be responsible, rather than an antibody-mediated rejection.
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