Expression of Bone Markers by Human Osteoblasts on Polymer Scaffolds

Objectives: Scaffolds are porous structures that play the role of a synthetic matrix and constitute a physical support for cell adhesion and growth. This study aimed at examining the in vitro effects of newly developed co-polymer scaffolds on the synthesis of osteoblast differentiation markers [alkaline phosphatase (ALP), osteocalcin (OC), collagen type I (Coll type I), bone sialoprotein (BSP) and runt-related transcription factor 2 (RUNX2)] by human osteoblast-like cells (HOB).

Methods: HOB derived from alveolar bone biopsies obtained from patients undergoing routine oral surgery were cultured in alpha-MEM medium with 10% FCS and 1% antibiotics on culture dishes (as a control) and on L-lactide (LLA) scaffolds copolymerized with 1,5-dioxepan-2-one (DXO-co-LLA) or with caprolactone (CL-co-LLA) as tests, and pore sizes within the range of 0-400 µm. Cells were harvested on day 1 and 14. Scanning electron microscopy (SEM) analyses were undertaken to determine cellular morphology and spread after 1 and 14 days of incubation. After 14 days the supernatants were collected, and the synthesis of OC and Coll typeI by HOB were measured by ELISA. Total RNA was extracted, and the expression of OC, Coll typeI, ALP, BSP and RUNX2 was quantified by real time reverse transcriptase PCR (QRT-PCR).

Results: SEM analysis showed that cells had spread well on the surfaces and through the pores of the polymers, indicating excellent attachment to all scaffolds investigated. ELISA analysis demonstrated higher synthesis of OC and Coll typeI on DXO scaffolds than CL. Increased expression of OC, Coll typeI, ALP, BSP and RUNX2 was found on DXO-co-LLA scaffolds compared to CL-co-LLA as measured by QRT-PCR.

Conclusion: The present in vitro study showed that the developed co-polymer scaffolds had promoted osteoblast differentiation indicating that these scaffolds might be appropriate carriers for bone engineering.

The study is supported by Helse Vest and The Research Council of Norway.