Static Magnetic Fields Enhance the Chondrogenesis of Mandibular Bone Marrow Mesenchymal Stem Cells in Coculture Systems

The present study was performed to examine the effect of intra- articular injection of bone marrow mesenchymal stem cells (BMMSCs) and chondrogenic differentiated mesenchymal stem cells (CD- MSCs) on the repair of articular cartilage defects in rabbits. Twenty-five adult female baladi rabbits were used in this work. 5 rabbits were used for preparation of bone marrow mesenchymal stem cells (BM-MSCs) and their left knees were not subjected for the surgical procedure and used as normal control group. The remaining twenty rabbits were subjected for surgically induced cartilage defects in their left knees through a small medial parapatellar incision using bone curette. In the next day, the rabbits were divided into four groups: group I was not injected intraarticularly, group II injected intra-articularly by a single dose of saline, group III injected intra-articularly by a single dose of BM-MSCs and group IV injected intra-articularly by a single dose of CD-MSCs. After 8 weeks from the time of intra-articular injection. On time the rabbits were sacrificed and the entire knee joints were excised and examined. Groups I and II showed marked degenerative changes in their articular cartilage. The articular surface healed by fibrocartilage in group III, while in group IV the articular surface healed by hyaline cartilage. Treatment by CD-MSCs promotes a better healing effect on the articular cartilage defects of injured knee joints in rabbit’s model and has a remarkable superiority of repair than BM-MSCs. This can prevent the progress of cartilage defect into osteoarthritis which was a harmful disease.

The craniofacial skeleton is the foundation of most stomatological treatments, including prosthodontics and maxillofacial surgery. Although histologically similar to the appendicular skeleton, the craniofacial skeleton manifests many unique properties in response to external stimuli and signals. However, the mandibular or maxillary bone marrow mesenchyme, which is the intrinsic foundation of the functions of craniofacial skeleton, has not been well studied, and its homeostasis mechanism remains elusive. Osteoporosis is a systemic disease that affects all skeletons and is characterized by bone mass loss. Osteoporotic bone marrow mesenchymal stem cells (BMMSCs) exhibit disturbed homeostasis and distorted lineage commitment. Many reports have shown that microRNAs (miRNAs) play important roles in regulating MSCs homeostasis. Here, to obtain a better understanding of mandibular bone marrow MSCs homeostasis, we isolated and cultured mandible marrow MSCs from mouse mandibles. Using miR-705 mimics and an inhibitor, we demonstrated that miR-705 played a vital role in shifting the mandibular MSCs lineage commitment in vitro. Utilizing an osteoporosis mouse model, we demonstrated that MSCs from ovariectomized (OVX) mouse mandibular bone marrow exhibited impaired osteogenic and excessive adipogenic differentiation. miR-705 was found overexpressed in OVX mandibular MSCs. The knock down of miR-705 in vitro partially attenuated the differentiation disorder of the OVX mandibular MSCs by upregulating the expression of osteogenic marker genes but suppressing adipogenic genes. Taken together, our findings provide a better understanding of the homeostasis mechanism of mandibular BMMSCs and a novel potential therapeutic target for treating mandibular osteoporosis.

In the present study, we have demonstrated that alginate and collagen sponge can act as scaffolds in order to support 3-dimensional structure for the differentiated bone marrow derived mesenchymal stem cells (BMSCs) during chondrogenesis in vitro and in vivo. The chondrogenic induced BMSCs were well distributed and differentiation in scaffolds system before implantation, then they produced sufficient ECM in the implants to form chondroid aggregates in vivo. In our opinion, well-differentiated BMSCs is a crucial feature of cartilage repair and only can be achieved in scaffold matrix. Furthermore, when dealing with cartilage defects, alginate seem to be superior to collagen sponge, and the combinational strategy of pre-induced BMSCs combined with alginate 3D-culture might be useful in improving conventional autologous cells transplantation or free-cells scaffolds.