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Polyetherketoneketone (PEKK) a high performance thermoplastic polymer that is FDA-approved for cranio- and maxillo-facial as well as spineal surgery. We studied the viability, growth and osteogenic differentiation of bone marrow-derived human and sheep mesenchymal stem cells (MSC) in combination with a 3D scaffold made of PEKK using different cell-based assays. To investigate if autologous MSC, either undifferentiated or osteogenically pre-differentiated, augmented bone formation after implantation, we implanted cell-seeded 3D PEKK scaffolds into calvarial defects in sheep for 12 weeks. The volume and quality of newly formed bone were investigated using micro-computer tomography (micro-CT) and histological stainings. Our results show that the 3D PEKK scaffolds were cyto- and bio-compatible. They allowed for adherence, growth and osteogenic differentiation of human and ovine MSC. However, bone healing seemed unaffected by whether the scaffolds were seeded with MSC. Considerable amounts of newly formed bone were found in all PEKK treated groups, but a fibrous capsule was formed around the implants regardless of cell seeding with MSC. European Association for Cranio-Maxillo-Facial Surgery.

Cord blood-derived haematopoietic stem cells (CB-HSCs) are an attractive source for transplantation in haematopoietic disorders. However, the yield of CB-HSCs per graft is limited and often insufficient, particularly for the treatment of adult patients. Here we compare the capacity of three cytokine cocktails to expand CB-CD34(+) cells. Cells were cultured for 5 or 14 days in media supplemented with: (a) SCF, FL, IL-3 and IL-6 (SFLIL3/6); (b) SCF, TPO, FGF-1 and IL-6 (STFIL6); and (c) SCF, TPO, FGF-1, IGFBP2 and Angptl-5 (STFAI). We observed that STFAI-culture expansion sustained the most vigorous cell proliferation, maintenance of CD34(+) phenotype and colony-forming unit counts. In addition, STFAI-cultured cells had a potent ex vivo migration activity. STFAI-expanded cells were able to engraft NSG mice. However, no significant difference in overall engraftment was observed among the expansion cocktails. Assessment of short-term reconstitution using multilineage markers demonstrated that the STFAI cocktail for HSCs expansion greatly improved total cell expansion but may impair short-term lymphoid repopulation.