| 1. |
- Abdulreda, MH, et al.
(författare)
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Challenges in stem cell-derived islet replacement therapy can be overcome
- 2021
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Ingår i: Cell transplantation. - : SAGE Publications. - 1555-3892 .- 0963-6897. ; 30, s. 9636897211045320-
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Tidskriftsartikel (refereegranskat)abstract
- In this Commentary, we echo the conclusions of a recent review titled “ The promise of stem cell-derived islet replacement therapy,” which highlighted recent advances in producing glucose responsive “islets” from stem cells and the benefits of their use in islet transplant therapy in type 1 diabetes (T1D). The review also outlined the status of clinical islet transplantation and the challenges that have prevented it from reaching its full therapeutic promise. We agree with the conclusions of the review and suggest that the identified challenges may be overcome by using the eye anterior chamber as an islet transplant site. We anticipate that the combination of stem cell-derived islets and intraocular transplant could help this promising T1D therapy reach full fruition.
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| 2. |
- Ballagi, A E, et al.
(författare)
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Platelet-derived growth factor receptor expression after neural grafting in a rat model of Parkinson's disease
- 1994
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 3:6, s. 453-460
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factor (PDGF) has trophic effect on dopaminergic neurons in vitro. We have previously shown dynamic changes in the expression of PDGF in embryonic mesencephalic grafts and surrounding host striatal tissue following intracerebral transplantation in a rat model of Parkinson's disease. In this study the expression of the PDGF receptors was examined in the same model using immunohistochemistry. Most ventral mesencephalic (VM) cells from E13-E15 rat embryos possessed both PDGF alpha- and beta-receptors before implantation. Double immunofluorescence staining revealed that about 10% of the cells also expressed tyrosine hydroxylase (TH). The PDGF alpha-receptor was detectable in the graft up to 1 wk after transplantation but had disappeared at 3 wk. In the host tissue, scattered glial cells were positive for the alpha-receptor but the expression was unchanged following transplantation. The beta-receptor expression almost completely disappeared from the grafted tissue by 4 h following transplantation, and only a few cells of the host striatum showed immunoreactivity. However, after 3 wk beta-receptor positive cells were again detectable in the graft. These cells appeared to be endothelial cells as identified by an antibody against von Willebrand's factor. Our data suggest that PDGF might act locally on embryonic dopaminergic cells in an autocrine or juxtacrine manner before and shortly after transplantation, and on surrounding glial cells in a paracrine manner after transplantation. Furthermore, PDGF-BB might influence neovascularization in the graft.
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| 3. |
- Benda, B, et al.
(författare)
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Co-stimulatory molecules in islet xenotransplantation: CTLA4Ig treatment in CD40 ligand-deficient mice
- 2002
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Ingår i: Cell transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 11:7, s. 715-720
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Tidskriftsartikel (refereegranskat)abstract
- Previous work has demonstrated that short-term systemic administration of cytotoxic T lymphocyte antigen-4 (CTLA-4) Ig blocks human pancreatic islet xenograft rejection in mice and induces long-term, donor-specific tolerance, whereas studies on pig pancreatic islet rejection in mice have failed to demonstrate a role for CTLA4Ig in preventing rejection. Treatment with anti-CD40 ligand (L) monoclonal antibodies alone is somewhat effective in prolonging the survival of islet xenografts, but ineffective when applied to skin xenografts. However, simultaneous blockade of the CD28 and CD40 co-stimulatory pathways prolongs the survival of pig skin on recipient mice. To evaluate the role of CD28 and CD40 co-stimulatory pathways in pig islet-like cell cluster (ICC) xenograft rejection in mice, CD40L-deficient mice transplanted with fetal porcine ICCs were given posttransplant treatment with human (h) CTLA4Ig or a human IgG1 chimeric mAb (hL6). Xenografts were evaluated 6 or 12 days after transplantation. Fetal porcine ICC xenografts were protected from rejection in hCTLA4Ig-treated CD40L-deficient mice, whereas xenograft rejection persisted in untreated CD40L-deficient mice. Simultaneous blockade of the CD28 and CD40 co-stimulatory pathways is mandatory to inhibit ICC xenograft rejection in the pig-to-mouse model, because the CD28 and CD40 co-stimulatory pathways seem capable of efficiently substituting for one another.
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| 4. |
- Bergström, Marcus, et al.
(författare)
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Comparing the Effects of the mTOR Inhibitors Azithromycin and Rapamycin on In Vitro Expanded Regulatory T Cells
- 2019
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Ingår i: Cell Transplantation. - : SAGE PUBLICATIONS INC. - 0963-6897 .- 1555-3892. ; 28:12, s. 1603-1613
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Tidskriftsartikel (refereegranskat)abstract
- Adoptive transfer of autologous polyclonal regulatory T cells (Tregs) is a promising option for reducing graft rejection in allogeneic transplantation. To gain therapeutic levels of Tregs there is a need to expand obtained cells ex vivo, usually in the presence of the mTOR inhibitor Rapamycin due to its ability to suppress proliferation of non-Treg T cells, thus promoting a purer Treg yield. Azithromycin is a bacteriostatic macrolide with mTOR inhibitory activity that has been shown to exert immunomodulatory effects on several types of immune cells. In this study we investigated the effects of Azithromycin, compared with Rapamycin, on Treg phenotype, growth, and function when expanding bulk, naive, and memory Tregs. Furthermore, the intracellular concentration of Rapamycin in CD4+ T cells as well as in the culture medium was measured for up to 48 h after supplemented. Treg phenotype was assessed by flow cytometry and Treg function was measured as inhibition of responder T-cell expansion in a suppression assay. The concentration of Rapamycin was quantified with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Azithromycin and Rapamycin both promoted a FoxP3-positive Treg phenotype in bulk Tregs, while Rapamycin also increased FoxP3 and FoxP3+Helios positivity in naive and memory Tregs. Furthermore, Rapamycin inhibited the expansion of naive Tregs, but also increased their suppressive effect. Rapamycin was quickly degraded in 37 degrees C medium, yet was retained intracellularly. While both compounds may benefit expansion of FoxP3+ Tregs in vitro, further studies elucidating the effects of Azithromycin treatment on Tregs are needed to determine its potential use.
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| 5. |
- Bluhme, E, et al.
(författare)
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Procurement and Evaluation of Hepatocytes for Transplantation From Neonatal Donors After Circulatory Death
- 2022
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Ingår i: Cell transplantation. - : SAGE Publications. - 1555-3892 .- 0963-6897. ; 31, s. 9636897211069900-
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Tidskriftsartikel (refereegranskat)abstract
- Hepatocyte transplantation is a promising treatment for liver failure and inborn metabolic liver diseases, but progress has been hampered by a scarcity of available organs. Here, hepatocytes isolated from livers procured for a neonatal hepatocyte donation program within a research setting were assessed for metabolic function and suitability for transplantation. Organ donation was considered for infants who died in neonatal intensive care in the Stockholm region during 2015–2021. Inclusion was assessed when a decision to discontinue life-sustaining treatment had been made and hepatectomy performed after declaration of death. Hepatocyte isolation was performed by three-step collagenase perfusion. Hepatocyte viability, yield, and function were assessed using fresh and cryopreserved cells. Engraftment and maturation of cryopreserved neonatal hepatocytes were assessed by transplantation into an immunodeficient mouse model and analysis of the gene expression of phase I, phase II, and liver-specific enzymes and proteins. Twelve livers were procured. Median warm ischemia time (WIT) was 190 [interquartile range (IQR): 80–210] minutes. Median viability was 86% (IQR: 71%–91%). Median yield was 6.9 (IQR: 3.4–12.8) x106 viable hepatocytes/g. Transplantation into immunodeficient mice resulted in good engraftment and maturation of hepatocyte-specific proteins and enzymes. A neonatal organ donation program including preterm born infants was found to be feasible. Hepatocytes isolated from neonatal donors had good viability, function, and engraftment despite prolonged WIT. Therefore, neonatal livers should be considered as a donor source for clinical hepatocyte transplantation, even in cases with extended WIT.
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| 6. |
- 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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| 7. |
- Brandhorst, Daniel, et al.
(författare)
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Multicenter Assessment of Animal-free Collagenase AF-1 for Human Islet Isolation
- 2017
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Ingår i: Cell Transplantation. - : Sage Publications. - 0963-6897 .- 1555-3892. ; 26:10, s. 1688-1693
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Tidskriftsartikel (refereegranskat)abstract
- Animal-free (AF) SERVA Collagenase AF-1 and Neutral Protease (NP) AF GMP Grade have recently become available for human islet isolation. This report describes the initial experiences of 3 different islet transplant centers. Thirty-four human pancreases were digested using 1 vial of the 6 different lots of Collagenase AF-1 (2,000-2,583 PZ-U/vial) supplemented with 4 different lots of NP AF in a range of 50 to 160 DMC-U per pancreas. Isolation, culture, and quality assessment were performed using standard techniques as previously described. All data are presented as mean +/- standard error of the mean (SEM). Variability of pancreas weight was associated with a wide range of collagenase and NP activities, ranging from 12.7 to 46.6 PZ-U/g (26.0 +/- 1.5 PZ-U/g) and 0.4 to 3.0 DMC-U/g (1.5 +/- 0.1 DMC-U/g), respectively. Postpurification islet yield was 296,494 +/- 33,620 islet equivalents (IEQ) equivalent to 3,274 +/- 450 IEQ/g with a purity of 55.9% +/- 3.2%. Quality assessment performed after 2 to 4 d of culture demonstrated a viability of 88.1% +/- 1.5% and a stimulation index of 3.7 +/- 0.7. Eighteen of the 34 preparations were transplanted into type 1 diabetic patients equivalent to a transplantation rate of 52.9%. Six preparations, which were infused into patients as first transplant, could be analyzed and increased the fasting C-peptide level from 0.11 +/- 0.08 pretransplant to 1.23 +/- 0.24 and 2.27 +/- 0.31 ng/mL 3 and 6 mo posttransplant (P < 0.05), respectively. Insulin requirements were simultaneously reduced at the same time from 39.2 +/- 3.8 IU/d before transplantation to 10.8 +/- 4.1 and 4.0 +/- 2.3 IU/d, after 3 and 6 mo posttransplant (P < 0.05), respectively. This study demonstrates the efficiency of AF SERVA Collagenase AF-1 and NP AF for clinical islet isolation and transplantation. The new plant-based production process makes these products a safe new option for the islet field.
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| 8. |
- 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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| 9. |
- Brandhorst, Heide, 1962-, et al.
(författare)
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Comparison of Clostripain and Neutral Protease as Supplementary Enzymes for Human Islet Isolation
- 2019
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Ingår i: Cell Transplantation. - : SAGE PUBLICATIONS INC. - 0963-6897 .- 1555-3892. ; 28:2, s. 176-184
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Tidskriftsartikel (refereegranskat)abstract
- Although human islet transplantation has been established as valid and safe treatment for patients with type 1 diabetes, the utilization rates of human pancreases for clinical islet transplantation are still limited and substantially determined by the quality and composition of collagenase blends. While function and integrity of collagenase has been extensively investigated, information is still lacking about the most suitable supplementary neutral proteases. The present study compared islet isolation outcome after pancreas digestion by means of collagenase used alone or supplemented with either neutral protease (NP), clostripain (CP), or both proteases. Decent amounts of islet equivalents (IEQ) were isolated using collagenase alone (3090 +/- 550 IEQ/g), or in combination with NP (2340 +/- 450 IEQ/g) or CP (2740 +/- 280 IEQ/g). Nevertheless, the proportion of undigested tissue was higher after using collagenase alone (21.1 +/- 1.1%, P < 0.05) compared with addition of NP (13.3 +/- 2.2%) or CP plus NP (13.7 +/- 2.6%). Likewise, the percentage of embedded islets was highest using collagenase only (13 +/- 2%) and lowest adding NP plus CP (4 +/- 1%, P < 0.01). The latter combination resulted in lowest post-culture overall survival (42.7 +/- 3.9%), while highest survival was observed after supplementation with CP (74.5 +/- 4.8%, P < 0.01). An insulin response toward glucose challenge was present in all experimental groups, but the stimulation index was significantly decreased using collagenase plus NP (2.0 +/- 0.12) compared with supplementation with CP (3.16 +/- 0.4, P < 0.001). This study demonstrates for the first time that it is possible to isolate significant numbers of human islets combining collagenase only with CP. The supplementation with CP is an effective means to substantially reduce NP activity, which significantly decreases survival and viability after culture. This will facilitate the manufacturing of enzyme blends with less harmful characteristics.
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| 10. |
- 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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