Jiaxu Lu,1,2,* Jiaxian Chen,2,* Youping Jiang,1,2 Yuanyuan Liu,1,2 Sheng Yu,2 Zhen Shi,2 Peicong Chen,2 Hao Lin,2 Peng Li1,2 

1Stem Cell Research and Cellular Therapy Center, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China; 2Orthopedic Center, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Hao Lin, Orthopedic Center, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China, Email linhao@gdmu.edu.cn Peng Li, Stem Cell Research and Cellular Therapy Center, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China, Email 13763086273@163.com

Introduction: Osteoporosis, a critical public health challenge, is marked by skeletal deformities and heightened fracture risk. Steleophaga plancyi (Boleny) (SP), a component of traditional Chinese medicine, is known to enhance bone health, but the molecular mechanisms behind its osteoprotective effects are not well understood.
Methods: We isolated extracellular vesicle (EV)-like particles from SP (SP-EVLP) using differential velocity centrifugation and investigated their effects on human bone marrow stromal cells (hBMSCs) in vitro. We utilized CCK-8, Alkaline phosphatase (ALP) and alizarin red staining (ARS), RNA-seq, bioinformatics, immunofluorescence, and Western blot to elucidate the osteoprotective role and mechanisms of SP-EVLP. The therapeutic potential of SP-EVLP was evaluated in an ovariectomized (OVX) rat model, a standard model for osteoporosis, by encapsulating them in enteric-coated capsules.
Results: SP-EVLP were successfully isolated and characterized, and they were shown to be effectively internalized by hBMSCs, enhancing osteogenic differentiation. In the OVX rat model, SP-EVLP encapsulated in enteric-coated capsules significantly increased bone mass, indicating a robust osteoprotective effect. Further mechanistic studies revealed that SP-EVLP promotes osteoblast proliferation by activating melatonin-induced autophagy, a pathway that may improve osteoporotic conditions.
Conclusion: Our results establish SP-EVLP as a promising therapeutic candidate for osteoporosis. The activation of melatonin-induced autophagy by SP-EVLP suggests a molecular mechanism for its osteoprotective effects, opening new possibilities for osteoporosis treatment development.

Keywords: Osteoporosis, Steleophaga plancyi (Boleny), extracellular vesicles (EV)-like particles, autophagy, melatonin