Increased BMP/SMAD Signaling by PD-MSCs Promotes Bone Formation in an Ovariectomized Mouse Model of Osteoporosis

Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic approach for degenerative diseases due to their ability to modulate disease progression through paracrine mechanisms. Among various MSC sources, placenta-derived MSCs (PD-MSCs) offer significant advantages, including high proliferation capacity, reduced senescence, and low immunogenicity, making them ideal for allogeneic applications. In this study, we investigated the therapeutic effects of PD-MSC transplantation in an estrogen-deficiency-induced osteoporosis mouse model. Mice were divided into three groups: a normal control group, a non-transplanted osteoporosis group, and a PD-MSC-transplanted group. Our findings demonstrated that PD-MSC transplantation significantly improved osteoporosis-related parameters, including increased femur weight, bone volume, bone mineral density, and calcium deposition. Additionally, estrogen levels were elevated, bone formation markers were upregulated, and bone resorption markers were downregulated. PD-MSCs also reduced inflammatory cytokine levels while enhancing anti-inflammatory factors. Notably, the BMP/SMAD signaling pathway, crucial for bone formation, was significantly upregulated. These results suggest that PD-MSC transplantation effectively restores bone homeostasis by inhibiting osteoclast activity, promoting osteogenesis, and modulating inflammation. This study provides strong evidence supporting the potential of PD-MSCs as a novel therapeutic strategy for osteoporosis, offering a regenerative and anti-inflammatory approach to bone disease management.