This work aimed at studying in vitro interactions between human tendon‐derived cells (hTDCs) and pre‐osteoblasts (pre‐OBs) that may trigger a cascade of events involved in enthesis regeneration.

The effect of 5 osteogenic medium (OM) conditions over the modulation of hTDCs and pre‐OBs towards the tenogenic and osteogenic phenotypes, respectively, was studied. Three different medium conditions were chosen for subsequently establishing a direct co‐culture system in order to study the expression of bone, tendon and interface‐related markers.

A higher matrix mineralization and ALP activity was observed in co‐cultures in the presence of OM. Higher transcription levels of bone‐ (ALPL, RUNX2, SPP1) and interface‐related genes (ACAN, COMP) were found in co‐cultures. The expression of aggrecan was influenced by the presence of OM and cell‐cell interactions occurring in co‐culture.

The present work assessed both the influence of OM on cell phenotype modulation and the importance of co‐culture models while promoting cell‐cell interactions and the exchange of soluble factors in triggering an interface‐like phenotype to potentially modulate enthesis regeneration.