Nanosheets-incorporated bio-composites containing natural and synthetic polymers/ceramics for bone tissue engineering.

Bone is a highly integrative and dynamic tissue of the human body that is regularly modeled and remodeled by bone cells such as osteoblasts and osteoclasts. When a fraction of a bone is damaged or deformed, stem cells and bone cells under the influence of several signaling pathways regulate bone regeneration at the particular locale, but in a dilatory manner. To overcome this problem, the field of bone tissue engineering (BTE) utilizes various bio-composite scaffolds that incorporate cells and appropriate growth factors to promote osteogenesis. Nanosheets are in two-dimensional (2D)-atomic structures, and metallic and non-metallic nanosheets play a keen role in biomedical applications, including BTE. Due to their intrinsic mechanical properties such as durability and flexibility, nanosheets strengthen the bio-composite scaffolds containing natural polymers (chitosan, gelatin, and collagen), synthetic polymers, bio-ceramics, and bio-glasses. Incorporating nanosheets into bio-composites promotes the bio-functionality of the cells, such as cell adhesion and osteoblast differentiation. Hence, this review was aimed to provide a detailed study on the nanosheets-incorporated bio-composites and their properties for BTE applications.

An osteoinductive effect of phytol on mouse mesenchymal stem cells (C3H10T1/2) towards osteoblasts.

In recent years, phytochemicals have been widely researched and utilized for the treatment of various medical conditions such as cancer, cardiovascular diseases, age-related problems and are also said to have bone regenerative effects. In this study, phytol (3,7,11,15-tetramethylhexadec-2-en-1-ol), an acyclic unsaturated diterpene alcohol and a secondary metabolite derived from aromatic plants was investigated for its effect on osteogenesis. Phytol was found to be nontoxic in mouse mesenchymal stem cells (C3H10T1/2). At the cellular level, phytol-treatment promoted osteoblast differentiation, as seen by the increased calcium deposits. At the molecular level, phytol-treatment stimulated the expression of Runx2 (a bone-related transcription factor) and other osteogenic marker genes. MicroRNAs (miRNAs) play an essential role in controlling bone metabolism by targeting genes at the post-transcriptional level. Upon phytol-treatment in C3H10T1/2 cells, mir-21a and Smad7 levels were increased and decreased, respectively. It was previously reported that mir-21a targets Smad7 (an antagonist of TGF-beta1 signaling) and thus, protects Runx2 from its degradation. Thus, based on our results, we suggest that phytol-treatment promoted osteoblast differentiation in C3H10T1/2 cells via Runx2 due to downregulation of Smad7 by mir-21a. Henceforth, phytol was identified to bolster osteoblast differentiation, which in turn may be used for bone regeneration.