Osteoblastic exosomes. A non-destructive quantitative approach of alkaline phosphatase to assess osteoconductive nanomaterials

Alkaline phosphatase (ALP) is an essential biomarker of osteoblastic activity. Currently, ALP activity has been used to study bone mineralization mechanisms and osteoactive biomaterials among others. The ALP quantification is usually performed by destructive methods either on growing cells or cells lysate in which the osteoconductive biomaterial is being assessed. This work addresses the evaluation of a non-destructive colorimetric approach for the determination of ALP activity on osteoblast-derived exosomes from culture supernatants. The efficiency of the method was evaluated on osteoconductive electrospun scaffolds of PCL compounded with ZnO as a reference biomaterial. The results demonstrated that the osteoblast cell line mineralization induced by osteoconductive scaffolds can be monitorized over time by the non-destructive measurement of ALP activity on osteoblast derived exosomes. Consequently, this non-destructive approach suggested to be a reliable alternative technique for the quantification of biomaterials osteoconductivity or even evaluation of osteoblastic response at stem cells. [Display omitted] •We present a novel non-destructive approach to measure in vitro ALP activity.•ALP expression is assessed directly on exosomes derived from osteoblast cells.•ALP activity can be evaluated over time on the same cell culture sample.•We assessed ALP expression on PCL-ZnO nanofibres scaffolds.•Our method quantifies ALP activity following clinical chemistry recommendations.