Healing and regeneration of bone injuries, particularly those that are associated with large bone defects, are a complicated process. There is growing interest in the application of osteoinductive and osteogenic growth factors and mesenchymal stem cells (MSCs) in order to significantly improve bone repair and regeneration. MSCs are multipotent stromal stem cells that can be harvested from many different sources and differentiated into a variety of cell types, such as preosteogenic chondroblasts and osteoblasts. The effectiveness of MSC therapy is dependent on several factors, including the differentiating state of the MSCs at the time of application, the method of their delivery, the concentration of MSCs per injection, the vehicle used, and the nature and extent of injury, for example. Tissue engineering and regenerative medicine, together with genetic engineering and gene therapy, are advanced options that may have the potential to improve the outcome of cell therapy. Although several in vitro and in vivo investigations have suggested the potential roles of MSCs in bone repair and regeneration, the mechanism of MSC therapy in bone repair has not been fully elucidated, the efficacy of MSC therapy has not been strongly proven in clinical trials, and several controversies exist, making it difficult to draw conclusions from the results. In this review, we update the recent advances in the mechanisms of MSC action and the delivery approaches in bone regenerative medicine. We will also review the most recent clinical trials to find out how MSCs may be beneficial for treating bone defects.

This study aimed to investigate effects of dental pulp stem cells (DPSCs) on regeneration of a defect experimentally created in the periodontium of a canine model. Surgically created mesial 3-walled periodontal defects with ligature-induced periodontitis were produced bilaterally in the first lower premolar teeth of 10 mongrel dogs. Simultaneously, DPSCs were derived from the maxillary premolar teeth of the same dogs. Four weeks after creation of the periodontitis model, autologous passaged-3 DPSCs combined with Bio-Oss were implanted on one side as the test group. On the other side, only Bio-Oss was implanted as a control. Eight weeks after surgery, regeneration of the periodontal defects was evaluated histologically and histomorphometrically in terms of bone, periodontal ligament (PDL), and cement formation. Histologically, in all test specimens (10 defects), regeneration of cementum, bone, and PDL was observed. In the control groups, although we observed the regeneration of bone in all defects, the formation of cementum was seen in 9 defects and PDL was seen in 8 defects. Histomorphometric analyses showed that the amount of regenerated cementum and PDL in the test groups (3.83 ± 1.32 mm and 3.30 ± 1.12 mm, respectively) was significantly higher than that of the control groups (2.42 ± 1.40 mm and 1.77 ± 1.27 mm, respectively; P< .05). A biocomplex consisting of DPSCs and Bio-Oss would be promising in regeneration of periodontal tissues.

Developing wisdom teeth are easy-accessible source of stem cells during the adulthood which could be obtained by routine orthodontic treatments. Human pulp-derived stem cells (hDPSCs) possess high proliferation potential with multi-lineage differentiation capacity compare to the ordinary source of adult stem cells [1][2][3][4][5][6][7][8]

While small bone defects heal spontaneously, large bone defects need surgical intervention for bone transplantation. Autologous bone grafts are the best and safest strategy for bone repair. An alternative method is to use allogenic bone graft. Both methods have limitations, particularly when bone defects are of a critical size. In these cases, bone constructs created by tissue engineering technologies are of utmost importance. Cells are one main component in the manufacture of bone construct. A few cell types, including embryonic stem cells (ESCs), adult osteoblast, and adult stem cells, can be used for this purpose. Mesenchymal stem cells (MSCs), as adult stem cells, possess characteristics that make them good candidate for bone repair. This paper discusses different aspects of MSCs that render them an appropriate cell type for clinical use to promote bone regeneration.

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Murine mesenchymal stem cells (mMSC) and the difficult task of isolation and purification of them have been the subject of rather extensive investigation. The present study sought to isolate these cells from two different mouse strains, one outbred and the other inbred, primarily through a relatively simple but novel approach, the most important feature of which was the low density primary culture of bone marrow cells. For this purpose, mononuclear cells from either NMRI or BALB/c bone marrow were plated at about 500 cells per well of 24-well plates and incubated for 7 days. At this point, the fibroblastic clones that had emerged were pooled together and expanded through several subcultures. To investigate the mesenchymal nature, we differentiated the cells into the osteoblastic, chondrocytic and adipocytic lineages in different subcultures up to passage 10. According to the results, 1 week after culture initiation, several clones each comprising several fibroblastic cells appeared in each plate. The cells from different passages were capable of differentiating into corresponding skeletal tissues. In the present investigation, the best culture condition for maximum proliferation and also the expression of certain surface marker on isolated cells were examined. In this term the two murine strains showed some differences.

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This study is devoted to fabricate a novel hydroxyapatite(HAp)/gelatin scaffold coated with nano-HAp in nano-rod configuration to evaluate its biocompatibility potential. The nano-HAp particles are needle and rod-like with widths ranging between 30 to 60 nm and lengths from 100 to 300 nm, respectively. Because of their higher surface area and higher reactivity, the nano-rod particles were distributed in gelatin much better than spherical and mixed shapes particles. The compressive modulus of the nano-HAp/gelatin scaffolds coated with nano-HAp was comparable with the compressive modulus of a human cancellous bone. The potential performance of the fabricated scaffolds as seeding media was assayed using mesenchymal stem cells (MSCs). MTT (3-(4,5-dimethylthiazol-2-yl)-1,5-diphenyl tetrazulium bromide) assays were performed on days 4 and 7 and the number of the cells per scaffold was determined. On the basis of this assay, all the studied scaffolds exhibited an appropriate environment in which the loaded cells appeared to be proliferated during the cultivation periods. In all fabricated composite scaffolds, marrow-derived MSCs appeared to occupy the scaffolds internal spaces and attach on their surfaces. According to the cell culture experiments, the incorporation of rod-like nano-HAp and coating of scaffolds with nano-HAp particles enabled the prepared scaffolds to possess desirable biocompatibility, high bioactivity, and sufficient mechanical strength in comparison with noncoated HAp samples. This research suggests that the newly developed scaffold has a potential as a suitable scaffold for bone tissue engineering.