In osteoporosis, bone loss is accompanied by an increase of adiposity in the marrow. A dialogue between adipocytes and osteoblasts is one of the ways occurring in the competition between Mesenchymal Stem Cells (MSCs) lineage commitments, supporting adipocyte differentiation at the expense of osteoblast differentiation. Using an in vitro coculture model based on human primary MSCs, we have previously shown that MSC-derived adipocytes are capable of inducing MSC-derived osteoblasts to differentiate towards an adipocyte-like phenotype. Indeed, upon coculture, MSC-derived osteoblasts showed appearance of adipocyte and decrease of late osteogenic mRNA markers. To confirm the co-localisation of adipogenic and osteoblastic proteins on a single cell level, we performed double immunofluorescence microscopic analyses. The results clearly showed an expression of osteoblast specific protein osteocalcin with adipogenic marker leptin in osteoblasts incubated with adipocytes conditioned medium, while in control osteoblasts expression of osteocalcin could only be observed. So, we provide evidence that MSC-derived osteoblasts can transdifferentiate into another lineage under the influence of secreted products release by MSC-derived adipocytes. We further aim to elucidate the mechanisms implicated in this phenotypic conversion, this knowledge being a prerequisite to target the competition between osteoblasts and adipocytes and to conceive a new approach for treatment of osteoporosis.
Disclosure: The authors declared no competing interests.