Gremlin-1 suppression increases BMP-2-induced osteogenesis of human mesenchymal stem cells

Abstract

Previous research focusing on rodent cells and animal models has demonstrated that gremlin-1 antagonizes bone morphogenetic proteins (BMPs) in order to suppress osteogenesis. However, the impact of gremlin‑1 on osteogenesis in human bone marrow-derived mesenchymal stem cells (MSCs) remains unknown. The aim of the present study was to test the effects of gremlin-1 on viability and in vitro BMP-2-induced osteogenic differentiation of human bone marrow‑derived mesenchymal stem cells (MSCs). Gremlin‑1‑specific small interfering RNA (siRNA) inhibited gremlin‑1 mRNA and protein expression in human MSCs. The mRNA expression levels of osteoblastic genes were analyzed using reverse transcription-quantitative polymerase chain reaction, and calcification and enzymatic alkaline phosphatase (ALP) activity assessed the BMP‑2‑induced osteogenic differentiation of human MSCs. The results indicated that gremlin‑1 suppression significantly increased human MSC metabolism and DNA content. The expression levels of osteoblastic genes were also significantly increased by gremlin‑1 inhibition. In the gremlin‑1‑inhibited group, enzymatic ALP activity was significantly increased. In addition, due to BMP‑2‑inducing osteoblasts, gremlin‑1 inhibition increased calcium deposits. The present study indicated that gremlin‑1 inhibited the cell viability and osteogenic differentiation of human MSCs and that the suppression of gremlin‑1 expression suppressed can increase the cell viability and osteogenic differentiation of human MSCs induced by BMP-2.