Calcium-type montmorillonite, a phyllosilicate mineral, has diverse health benefits when introduced into the gastrointestinal tract or applied to the skin. However, the predominant use of this layered material has thus far been in traditional industries, despite its potential application in the pharmaceutical industry. We investigated the effects and mechanism of nano-montmorillonite (NM) on osteoblast and osteoclast differentiation in vivo and in vitro. We examined the osteogenic effects of NM with high calcium content (3.66 wt%) on alkaline phosphatase (ALP) activity, mineralization, bone microarchitecture, and expression level of osteoblast and osteoclast related genes in Ca-deficient ovariectomized (OVX) rats. Micro-computed tomography of OVX rats revealed that NM attenuated the low-Ca-associated changes in trabecular and cortical bone mineral density. It improved ALP activity and mineralization, as well as the expression of osteoblast and osteoclast differentiation associated genes. NM also activated the expression of runt-related transcription factor 2, osteocalcin, bone morphogenetic protein 2, and type 1 collagen via phosphorylated small mothers against decapentaplegic homolog 1/5/8 signaling. Further, NM repressed the expression of receptor activator for cathepsin K, nuclear factor kappa-B ligand and tartrate-resistant acid phosphatase. Therefore, NM inhibits osteoclastogenesis, stimulates osteoblastogenesis, and alleviates osteoporosis.
Keywords: bone formation; nano-montmorillonite; osteoblasts; osteoclasts; ovariectomy rats.