Tailored generation of insulin producing cells from canine mesenchymal stem cells derived from bone marrow and adipose tissue

The trend of regenerative therapy for diabetes in human and veterinary practices has conceptually been proven according to the Edmonton protocol and animal models. Establishing an alternative insulin-producing cell (IPC) resource for further clinical application is a challenging task. This study investigated IPC generation from two practical canine mesenchymal stem cells (cMSCs), canine bone marrow-derived MSCs (cBM-MSCs) and canine adipose-derived MSCs (cAD-MSCs). The results illustrated that cBM-MSCs and cAD-MSCs contain distinct pancreatic differentiation potential and require the tailor-made induction protocols. The effective generation of cBM-MSC-derived IPCs needs the integration of genetic and microenvironment manipulation using a hanging-drop culture of PDX1-transfected cBM-MSCs under a three-step pancreatic induction protocol. However, this protocol is resource- and time-consuming. Another study on cAD-MSC-derived IPC generation found that IPC colonies could be obtained by a low attachment culture under the three-step induction protocol. Further, Notch signaling inhibition during pancreatic endoderm/progenitor induction yielded IPC colonies through the trend of glucose-responsive C-peptide secretion. Thus, this study showed that IPCs could be obtained from cBM-MSCs and cAD-MSCs through different induction techniques. Also, further signaling manipulation studies should be conducted to maximize the protocol’s efficiency.

Tailor-made generation of insulin-producing cells from canine mesenchymal stem cells derived from bone marrow and adipose tissue

Trend of regenerative therapy for diabetes in human and veterinary practice has conceptually been proven according to Edmonton protocol and animal models. Establishing an alternative insulin-producing cell (IPC) resource is a challenge task for further clinical application. In this study, IPC generation from two practical canine mesenchymal stem cells(cMSCs), canine bone marrow-derived MSCs (cBM-MSCs) and canine adipose-derived MSCs(cAD-MSCs), was of interest. The results illustrated that cBM-MSCs and cAD-MSCs contained distinct pancreatic differentiation potential and required the tailor-made induction protocols. Effective generation of cBM-MSC-derived IPCs needed an integration of genetic and microenvironment manipulation using hanging-drop culture of PDX-1-transfected cBM-MSCs under three-step pancreatic induction protocol. However, this protocol was resource- and time-consumed. Another study on cAD-MSC-derived IPC generation found that IPC colonies could be obtained by low attachment culture under three-step induction protocol. Further Notch signaling inhibition during pancreatic endoderm/progenitor induction yielded IPC colonies with trend of glucose-responsive C-peptide secretion. Thus, this study showed that IPCs could be obtained from cBM-MSCs and cAD-MSCs by different induction techniques, and further signaling manipulation study should be conducted to maximize the protocol efficiency.

Antithrombotic therapy in pediatric ventricular assist devices: Multicenter survey of the European EXCOR Pediatric Investigator Group

Objectives: Mechanical circulatory support for pediatric heart failure patients with the Berlin Heart EXCOR ventricular assist system is the only approved and established bridging strategy for recovery or heart transplantation. In recent years, the burden of thromboembolic events has led to modifications of the recommended antithrombotic therapy. Therefore, we aimed to assess modifications of antithrombotic practice among the European EXCOR Pediatric Investigator Group members. Methods: We sent a questionnaire assessing seven aspects of antithrombotic therapy to 18 European hospitals using the EXCOR device for children. Returned questionnaires were analyzed and identified antithrombotic strategies were descriptively compared to “Edmonton protocol” recommendations developed for the US EXCOR pediatric approval study. Results: Analysis of 18 received surveys revealed substantial deviations from the Edmonton protocol, including earlier start of heparin therapy at 6–12 h postoperatively and in 50% of surveyed centers, monitoring of heparin effectiveness with aPTT assay, administering vitamin K antagonists before 12 months of age. About 39% of centers use higher international normalized ratio targets, and platelet inhibition is changed in 56% including the use of clopidogrel instead of dipyridamole. Significant inter-center variability with multiple deviations from the Edmonton protocol was discovered with only one center following the Edmonton protocol completely. Conclusion: Current antithrombotic practice among European EXCOR users representing the treatment of more than 600 pediatric patients has changed over time with a trend toward a more aggressive therapy. There is a need for systematic evidence-based evaluation and harmonization of developmentally adjusted antithrombotic management practices in prospective studies toward revised recommendations.

Modular tissue engineering for the vascularization of subcutaneously transplanted pancreatic islets

The transplantation of pancreatic islets, following the Edmonton Protocol, is a promising treatment for type I diabetics. However, the need for multiple donors to achieve insulin independence reflects the large loss of islets that occurs when islets are infused into the portal vein. Finding a less hostile transplantation site that is both minimally invasive and able to support a large transplant volume is necessary to advance this approach. Although the s.c. site satisfies both these criteria, the site is poorly vascularized, precluding its utility. To address this problem, we demonstrate that modular tissue engineering results in an s.c. vascularized bed that enables the transplantation of pancreatic islets. In streptozotocin-induced diabetic SCID/beige mice, the injection of 750 rat islet equivalents embedded in endothelialized collagen modules was sufficient to restore and maintain normoglycemia for 21 days; the same number of free islets was unable to affect glucose levels. Furthermore, using CLARITY, we showed that embedded islets became revascularized and integrated with the host’s vasculature, a feature not seen in other s.c. studies. Collagen-embedded islets drove a small (albeit not significant) shift toward a proangiogenic CD206+MHCII−(M2-like) macrophage response, which was a feature of module-associated vascularization. While these results open the potential for using s.c. islet delivery as a treatment option for type I diabetes, the more immediate benefit may be for the exploration of revascularized islet biology.

Stem Cells as a Tool to Improve Outcomes of Islet Transplantation

The publication of the promising results of the Edmonton protocol in 2000 generated optimism for islet transplantation as a potential cure for Type 1 Diabetes Mellitus. Unfortunately, follow-up data revealed that less than 10% of patients achieved long-term insulin independence. More recent data from other large trials like the Collaborative Islet Transplant Registry show incremental improvement with 44% of islet transplant recipients maintaining insulin independence at three years of follow-up. Multiple underlying issues have been identified that contribute to islet graft failure, and newer research has attempted to address these problems. Stem cells have been utilized not only as a functional replacement forβcells, but also as companion or supportive cells to address a variety of different obstacles that prevent ideal graft viability and function. In this paper, we outline the manners in which stem cells have been applied to address barriers to the achievement of long-term insulin independence following islet transplantation.

Pancreas Procurement and Preservation for Islet Transplantation: Personal Considerations

Pancreatic islet transplantation is a promising option for the treatment of type 1 diabetic patients. After the successful demonstration of the Edmonton protocol, islet transplantation has advanced significantly on several fronts, including improved pancreas procurement and preservation systems. Since we frequently use pancreata from donors after cardiac death in Japan,we have applied thein situregional organ cooling system for pancreas procurement to reduce the warm ischemic time. To reduce the apoptosis of pancreatic tissue during cold preservation, we have applied the ductal injection of preservation solution. For pancreas preservation, we use modified Kyoto solution, which is advantageous at trypsin inhibition and less collagenase inhibition. In this paper, we show pancreas procurement and preservation in our group for islet transplantation.