Search

Background: Fractures with a critical size bone defect are associated with high rates of delayed- and non-union. The treatment of such complications remains a serious issue in orthopaedic surgery. Adipose derived stem cells (ASCs) combined with biomimetic materials can potentially be used to increase fracture healing. Nevertheless, a number of requirements have to be fulfilled; in particular, the insufficient vascularisation of the bone constructs. Here, the objectives were to study the impact of ASC-derived osteoblasts on ASC-derived endothelial cells in a 3D co-culture and the effect of 40wt% of amorphous calcium phosphate nanoparticles on the proliferation and differentiation of ASC-derived endothelial cells when present in PLGA., Materials and Methods: Five primary ASC lines were differentiated towards osteoblasts (OBs) and endothelial cells (ECs) and two of them were chosen based on quantitative PCR results. Either a mono-culture of ASC-derived EC or a co-culture of ASC-derived EC with ASC-derived OB (1:1) was seeded on an electrospun nanocomposite of poly-(lactic-co-glycolic acid) and amorphous calcium phosphate nanoparticles (PLGA/a-CaP; reference: PLGA). The proliferation behaviour was determined histomorphometrically in different zones and the expression of von Willebrand Factor (vWF) was quantified., Results: Independently of the fat source (biologic variability), ASC-derived osteoblasts decelerated the proliferation behaviour of ASC-derived endothelial cells in the co-culture compared to the mono-culture. However, expression of vWF was clearly stronger in the co-culture, indicating further differentiation of the ASC-derived EC into the EC lineage. Moreover, the presence of a-CaP nanoparticles in the scaffold slowed the proliferation behaviour of the co-culture cells, too, going along with a further differentiation of the ASC-derived OB, when compared to pure PLGA scaffolds., Conclusions: This study revealed significant findings for bone tissue-engineering. Co-cultures of ASC-derived EC and ASC-derived OB stimulate each other's further differentiation. A nanocomposite with a-CaP nanoparticles offers higher mechanical stability, bioactivity and osteoconductivity compared to mere PLGA and can easily be seeded with pre-differentiated EC and OB., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

For tissue engineering of critical size bone grafts, nanocomposites are getting more and more attractive due to their controllable physical and biological properties. We report in vitro and in vivo behaviour of an electrospun nanocomposite based on poly-lactic-co-glycolic acid and amorphous calcium phosphate nanoparticles (PLGA/a-CaP) seeded with human adipose-derived stem cells (ASC) compared to PLGA. Major findings were that cell attachment, three-dimensional ingrowth and proliferation were very good on both materials. Cell morphology changed from a spindle-shaped fibroblast-like form to a more roundish type when ASC were seeded on PLGA, while they retained their morphology on PLGA/a-CaP. Moreover, we found ASC differentiation to a phenotype committed towards osteogenesis when a-CaP nanoparticles were suspended in normal culture medium without any osteogenic supplements, which renders a-CaP nanoparticles an interesting osteoinductive component for the synthesis of other nanocomposites than PLGA/a-CaP. Finally, electrospun PLGA/a-CaP scaffold architecture is suitable for a rapid and homogenous vascularisation confirmed by a complete penetration by avian vessels from the chick chorioallantoic membrane (CAM) within one week., (Copyright © 2012 Elsevier Ltd. All rights reserved.)