Transplantation of osteoblast-like cells to the distracted callus in the rabbit mandible

Mandibular distraction osteogenesis assisted by cell-based tissue engineering: a systematic review

OBJECTIVES

To review the advances and limitations of recent investigations on mandibular distraction osteogenesis (MDO) assisted by mesenchymal stem cell (MSC) transplantation.

MATERIALS AND METHODS

Following the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines, the PubMed, Scopus, and Cochrane electronic databases were systematically searched and screened from their inception through August 2014. Searching terms included the following: 'distraction osteogenesis', 'mandible OR mandibular OR jaw', and 'cells', without any other limitations.

RESULTS

Nineteen studies meeting the eligibility criteria were selected from 227 published articles and used for qualitative synthesis. Fifteen of the studies used small animal models (rats or rabbits), while the other four used large animal models (dogs, pigs or sheep). Among these studies, large variations exist in MDO protocol, cell transplantation time, route and quantity, as well as methodology of outcome assessment. Additionally, all studies had certain biases. Nevertheless, the majority of studies found that MSC transplantation enhanced MDO bone regeneration.

CONCLUSION

Evidence from animal studies indicates that MDO may be enhanced by mesenchymal stem cell transplantation, but many questions related to animal models, MDO protocols, and cell transplantation remain to be investigated.

Transplantation of human dental pulp stem cells: enhance bone consolidation in mandibular distraction osteogenesis

PURPOSE

The main aim of the present study was to evaluate the capacity of stem cells from human exfoliated deciduous teeth (SHED) to enhance mandibular distraction osteogenesis (DO) in rabbits.

MATERIALS AND METHODS

A randomized controlled trial was conducted. Eighteen skeletally immature New Zealand white rabbits were divided into 2 groups, with 9 in the control group and 9 in the SHED group. The SHED were isolated, expanded, and characterized. Six million cells were transplanted into the distracted area during the osteotomy period. After a 4-day latency period, a total of 6 mm was distracted for 6 days. The newly formed bone was analyzed radiologically, histologically, and histomorphometrically at 2, 4, and 6 weeks postoperatively. Nonparametric analysis of variance (Kruskal-Wallis test) was used for data analysis, and P < .05 was considered statistically significant.

RESULTS

The cell lineage was positive for the 2 mesenchymal stem cell markers tested (CD105 and CD166). More mature bone in the SHED transplanted group was observed radiographically and histologically. Histomorphologically, the percentage of newly formed bone after 2, 4, and 6 weeks was 18.41% and 41.53%, 31.68% and 59.78%, and 52.34% and 65.24% in the control and SHED groups, respectively. The difference between the groups was statistically significant (P = .012). The bone union and stage of bone maturity scores were significantly different between the control and SHED groups (P = .006 and P = .011, respectively).

CONCLUSIONS

Our findings suggest that SHED can serve as an additional cell resource for DO enhancement in rabbits and might be a promising model for the reconstruction of large mandibular defects in human oral maxillofacial surgery.

Locally injection of cell sheet fragments enhances new bone formation in mandibular distraction osteogenesis: a rabbit model

Effective methods to shorten the treatment period of distraction osteogenesis (DO) are needed. To investigate whether injections of osteogenic bone marrow stromal cell (BMSC) sheet fragments could be used to facilitate new bone formation during DO, 30 rabbits underwent bilateral mandibular osteotomy and their mandibles were lengthened at a rate of 0.75 mm/12 h for 6 days after a 5-day latency period. There were three treatment groups (n = 10 for each group): Serum-free medium, dissociated BMSCs, and BMSC sheet fragments. A local injection was conducted with a needle directly into the distracted areas immediately after distraction. Rabbits were sacrificed for examination at 3 and 6 weeks after injection. Gross examination, radiographic evaluation, and micro-CT scanning indicated a significant increase in bony union in the BMSC sheet fragment group, compared with the medium group and the dissociated cell group. The histomorphometric analysis showed more intensive bone formation in the sheet fragment group than the other two groups at each time point. Additionally, the peak load was significantly higher in the fragment group than those in the others. The results show that injection of BMSC sheet fragments promotes bone formation in DO and indicate a promising approach to shorten the treatment period of osteodistraction.

Autologous rabbit adipose tissue-derived mesenchymal stromal cells for the treatment of bone injuries with distraction osteogenesis

BACKGROUND AIMS

Adipose tissue-derived mesenchymal stromal cells (MSCs) have a higher capacity for proliferation and differentiation compared with other cell lineages. Although distraction osteogenesis is the most important therapy for treating bone defects, this treatment is restricted in many situations. The aim of this study was to examine the therapeutic potential of adipose tissue-derived MSCs and osteoblasts differentiated from adipose tissue-derived MSCs in the treatment of bone defects.

METHODS

Bone defects were produced in the tibias of New Zealand rabbits that had previously undergone adipose tissue extraction. Tibial osteotomy was performed, and a distractor was placed on the right leg of the rabbits. The rabbits were placed in control (group I), stem cell (group II) and osteoblast-differentiated stem cell (group III) treatment groups. The rabbits were sacrificed, and the defect area was evaluated by radiologic, biomechanical and histopathologic tests to examine the therapeutic effects of adipose tissue-derived MSCs.

RESULTS

Radiologic analyses revealed that callus density and the ossification rate increased in group III compared with group I and group II. In biomechanical tests, the highest ossification rate was observed in group III. Histopathologic studies showed that the quality of newly formed bone and the number of cells active in bone formation were significantly higher in group III rabbits compared with group I and group II rabbits.

CONCLUSIONS

These data reveal that osteoblasts differentiated from adipose tissue-derived MSCs shorten the consolidation period of distraction osteogenesis. Stem cells could be used as an effective treatment for bone defects.

Implantation of osteogenic differentiated donor mesenchymal stem cells causes recruitment of host cells

The interaction between host and donor cells is believed to play an important role in osteogenesis. However, it is still unclear how donor osteogenic cells behave and interact with host cells in vivo. The purpose of this study was to track the interactions between transplanted osteogenic cells and host cells during osteogenesis. In vitro migration assay was carried out to investigate the ability of osteogenic differentiated human mesenchymal stem cells (O-hMSCs) to recruit MSCs. At the in vivo level, O-hMSCs were implanted subcutaneously or into skull defects in severe combined immunodeficient (SCID) mice. New bone formation was observed by micro-CT and histological procedures. In situ hybridization (ISH) against human Alu sequences was performed to distinguish donor osteogenic cells from host cells. In vitro migration assay revealed an increased migration potential of MSCs by co-culturing with O-hMSCs. In agreement with the results of in vitro studies, ISH against human Alu sequences showed that host mouse MSCs migrated in large numbers into the transplantation site in response to O-hMSCs. Interestingly, host cells recruited by O-hMSCs were the major cell populations in newly formed bone tissues, indicating that O-hMSCs can trigger and initiate osteogenesis when transplanted in orthotopic sites. The observations from this study demonstrated that in vitro induced O-hMSCs were able to attract host MSCs in vivo and were involved in osteogenesis together with host cells, which may be of importance for bone tissue-engineering applications.

Effect of icariin on bone formation during distraction osteogenesis in the rabbit mandible

The aim of this study was to evaluate the effect of icariin on bone formation during mandibular distraction. 40 Rabbits were randomly divided into experimental and control groups. Mandibular distraction was performed 5 days after unilateral mandibular osteotomy using a custom-made external distractor at a rate of 0.5mm/12h for 10 days. From the first day of distraction, icariin (2.5mg/kg · day) was orally administered to the experimental group and placebo to the controls. 10 Rabbits were killed at the end of weeks 2 and 4 of the consolidation phase. The distracted hemimandible was harvested and newly formed bone was evaluated by soft radiography, histology and bone histomorphometry. Regenerated bone was evaluated for bone mineral density by dual-energy X-ray absorptiometry. The experimental group had fewer radiolucent areas on soft radiography. Bone mineral density of regenerated bone was higher in the experimental than in the control group at 2 and 4 weeks. At 4 weeks, the experimental group had greater volumes of new bone, higher trabecular number, and less trabecular separation than the controls. Oral administration of icariin could promote bone formation during mandibular distraction osteogenesis and might be a promising method for shortening the course of distraction osteogenesis.