Human amnion mesenchymal stem cells (HAMSCs) can be obtained from human amniotic membrane, a highly abundant and readily available tissue. HAMSC sources present fewer ethical issues, have low immunogenicity, anti-inflammatory properties, considerable advantageous characteristics, and are considered an attractive potential treatment material in the field of regenerative medicine. We used a co-culture system to determine whether HAMSCs could promote osteogenesis in human bone marrow mesenchymal stem cells (HBMSCs). We isolated HAMSCs from discarded amnion samples and collected them using pancreatin/collagenase digestion. We cultured HAMSCs and HBMSCSs in basal medium. Activity of alkaline phosphatase (ALP), an early osteogenesis marker, was increased in the co-culture system compared to the control single cultures, which we also confirmed by ALP staining. We used immunofluorescence testing to investigate the effects of co-culturing with HAMSCs on HBMSC proliferation, which revealed that the co-culturing enhanced EdU expression in HBMSCs. Western blotting and quantitative real-time PCR indicated that co-culturing promoted osteogenesis in HBMSCs. Furthermore, Alizarin red S staining revealed that extracellular matrix calcium levels in mineralized nodule formation produced by the co-cultures were higher than that in the controls. Using the same co-culture system, we further observed the effects of HAMSCs on osteogenic differentiation in primary osteoblasts by Western blotting, which better addressed the mechanism for HAMSCs in bone regeneration. The results showed HAMSCs are osteogenic and not only play a role in promoting HBMSC proliferation and osteogenic differentiation but also in osteoblasts, laying the foundation for new regenerative medicine methods.

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Mandible osteoporosis with age is characterized by greater fragility and accompanied with abnormal oral function. Mesenchymal stem cell transplantation can ameliorate osteoporosis. Bmi‐1 is a transcriptional repressor which is an important regulator of cell cycle, stem cells self‐renewal, and cell senescence. Here, we use a new kind of membrane mesenchymal stem cells (MSCs), amniotic membrane mesenchymal stem cells (AMSCs), to explore therapeutic effects on Bmi‐1‐deficient caused mandible osteoporosis. Phenotypes of mandibles from 5‐week‐old Bmi‐1‐deficient mice with AMSCs‐based therapy were compared with age‐matched Bmi‐1‐deficient mandibles without AMSCs‐based therapy and wild‐type mice. Bmi‐1‐deficient mice without AMSCs‐based therapy displayed mandible osteoporosis accompanied with the rising senescence‐associated molecules and imbalance redox homeostasis. Results showed that the alveolar bone volume, cortical thickness, type I collagen and osteocalcin immunopositive areas, mRNA expression levels of alkaline phosphatase, superoxide dismutase, gluathione reductase, and protein expression level of Runx2 were all reduced significantly in Bmi‐1−/− mandibles. Protein levels of PPARγ, p16, p21, p53, and redox gene levels of Bnip3l, Cdo1, Duox1, and Duox2 were up‐regulated in mandibles from vehicle‐transplanted Bmi‐1−/− mice. Also, osteoclasts were activated in Bmi‐1−/− alveolar bone. Transplanted AMSCs migrated into mandibles and improved all the parameters in Bmi‐1−/− mandibles with AMSCs‐based therapy. These findings indicate that AMSCs‐based therapy could rescue mandible osteoporosis induced by Bmi‐1 deficiency through stimulating osteoblastic bone formation and inhibiting osteoclastic bone resorption. Our findings implied that AMSCs‐based therapy had preventative and therapeutic potential for mandible osteoporosis.