Combined scanning probe microscopy and x-ray scattering instrument for in situ catalysis investigations

Catalysis and Surface Chemistr

Galactosyl-knock-out engineered pig as a xenogenic donor source of adipose MSCs for bone regeneration.

Pig adipose mesenchymal stem cells (AMSCs) could be proposed for the improvement of bone substitute. However, these xenogenic cells retain a galactosyl (Gal) epitope that elicits xenorejection. Our work aims to use Gal-Knock-Out (Gal-KO) pig AMSCs to associate cellular immunomodulation, humoral down-elicitation of Gal-KO cells and osteogenic capacity of AMSCs. Human and pig AMSCs were compared for proliferation/differentiation kinetics and bone neoformation in vivo. Humoral reaction against pig Gal+ vs. Gal-KO AMSCs and immunomodulation properties of Gal+ vs. Gal-KO AMSCs were assessed in vitro. Humoral/cellular reactions against Gal+ vs. Gal-KO osteogenic differentiated pig AMSC xenografts were assessed in an immunocompetent rodent model. Expansion/differentiation/bone neoformation was significantly improved with differentiated pig AMSCs compared with human cells. Based on immunohistochemistry and cell-based ELISA, Gal+ AMSCs had higher sensitivity to preformed/induced anti-pig antibodies than Gal-KO AMSCs. In vitro cellular immunomodulation was similar between Gal+ and Gal-KO AMSCs. In vivo, a significant reduction of anti-pig IgG was found at 1 month in rats implanted with Gal-KO AMSCs compared with those implanted with Gal+ AMSCs. Lymphocyte/macrophage infiltration of osteogenic differentiated pig AMSC xenografts was significantly lower at post-operative day (POD) 7 in recipients of Gal-KO vs. Gal+ pig cells. No significant difference was found at POD 28. The combination of the cellular immunomodulation with the Gal-KO phenotype of AMSCs can significantly improve the cellular engraftment of pig osteogenic cells by delaying xenorejection

Beta-5 Score to evaluate pig islet graft function in a primate pre-clinical model

BACKGROUND: We developed a composite scoring system to accurately assess pig islet function in pre-clinical primate studies. METHODS: Two scoring methods that have been clinically validated in human islet allotransplantation were tested in six non-diabetic and nine streptozotocin (STZ)-induced diabetic primates: (i) SUITO index=[1500 × fasting C-peptide (ng/ml)]/[fasting blood glucose (FBG, mg/dl) - 63] and (ii) CP/G ratio =[fasting C-peptide (ng/ml) × 100]/FBG (mg/dl). Both scores were analysed as a function of the β-cell mass of the native primate pancreas. Next, a proposed β5 score based on FBG values, daily glycosuria, post-prandial glycosuria, polydipsia, and polyuria was validated on the same primates. Ranges of normal and pathologic values for each parameter were assessed during 5 months in non-diabetic and diabetic primates, respectively. Finally, scores were tested on the nine STZ-induced diabetic primates, four of which were transplanted with microencapsulated pig islets and five with macroencapsulated pig islets. All parameters required for each score were measured prior to transplantation and up to 12 weeks post-transplantation. For the CP/G ratio after transplantation, primate C-peptide was replaced by porcine C-peptide. RESULTS: The Suito index was not correlated with the pancreatic β-cell mass in contrast to the CP/G ratio (R(2) = 0.17, P = 0.645 vs. R(2) = 0.76, P = 0.003; respectively). The internal consistency of the parameters implied by the β5 score was confirmed by a Cronbach's alpha test of 0.97. Diabetes was confirmed by a significant decrease in the CP/G ratio and the β5 score before and after diabetes induction, respectively. After transplantation, a significant correlation was found between the CP/G ratio and the β5 score, which reflected the functionality of pig islet xenografts and diabetes control. In addition, the CP/G ratio and β5 score were correlated with the glycosylated hemoglobin course after transplantation and diabetes correction with macroencapsulated pig islets. CONCLUSION: The proposed β5 score provides a valid tool to accurately assess islet transplantation in a primate pre-clinical model

Critical size bone defect reconstruction by an autologous 3D osteogenic-like tissue derived from differentiated adipose MSCs

For critical size bone defects and bone non-unions, bone tissue engineering using osteoblastic differentiated adipose mesenchymal stem cells (AMSCs) is limited by the need for a biomaterial to support cell transplantation. An osteoblastic three-dimensional autologous graft made of AMSCs (3D AMSC) was developed to solve this issue. This autograft was obtained by supplementing the osteoblastic differentiation medium with demineralized bone matrix. Two surgical models were developed to assess the potential of this 3D osteogenic AMSC autograft. A four-level spinal fusion using polyetheretherketone cages was designed in six pigs to assess the early phase of ossification (8-12 weeks postimplantation). In each pig, four groups were compared: cancellous bone autograft, freeze-dried irradiated cancellous pig bone, 3D AMSC, and an empty cage. A critical size femoral defect (n = 4, bone non-union confirmed 6 months postoperatively) was used to assess the 3D AMSCs' ability to achieve bone fusion. Pigs were followed by CT scan and explanted specimens were analyzed for bone tissue remodeling by micro-CT scan, micro-radiography, and histology/histomorphometry. In the spine fusion model, bone formation with the 3D AMSC was demonstrated by a significant increase in bone content. In the critical-size femoral defect model, the 3D AMSC achieved new bone formation and fusion in a poorly vascularized fibrotic environment. This custom-made 3D osteogenic AMSC autograft is a therapeutic solution for bone non-unions and for critical-size defects