Efficacy of stem cells in maxillary sinus floor augmentation: systematic review and meta-analysis

Efficacy of mesenchymal stem cell-based therapy on the bone repair of hypertensive rats

OBJECTIVE

Hypertension disrupts the bone integrity and its repair ability. This study explores the efficiency of a therapy based on the application of mesenchymal stem cells (MSCs) to repair bone defects of spontaneously hypertensive rats (SHR).

METHODS

First, we evaluated SHR in terms of bone morphometry and differentiation of MSCs into osteoblasts. Then, the effects of the interactions between MSCs from normotensive rats (NTR-MSCs) cocultured with SHR (SHR-MSCs) on the osteoblast differentiation of both cell populations were evaluated. Also, bone formation into calvarial defects of SHR treated with NTR-MSCs was analyzed.

RESULTS

Hypertension induced bone loss evidenced by reduced bone morphometric parameters of femurs of SHR compared with NTR as well as decreased osteoblast differentiation of SHR-MSCs compared with NTR-MSCs. NTR-MSCs partially restored the capacity of SHR-MSCs to differentiate into osteoblasts, while SHR-MSCs exhibited a slight negative effect on NTR-MSCs. An enhanced bone repair was observed in defects treated with NTR-MSCs compared with control, stressing this cell therapy efficacy even in bones damaged by hypertension.

CONCLUSION

The use of MSCs derived from a heathy environment can be in the near future a smart approach to treat bone loss in the context of regenerative dentistry for oral rehabilitation of hypertensive patients.

Radiographic outcome after maxillary sinus floor augmentation with allogeneic adipose tissue-derived stem cells seeded on deproteinized bovine bone mineral. A randomized controlled experimental study

The objective was to test the hypothesis of no difference in radiographic outcome after maxillary sinus floor augmentation (MSFA) with allogeneic adipose tissue-derived stem cells (ASCs) seeded on deproteinized bovine bone mineral (DBBM) (test) compared with excipient on DBBM (control). Eighteen minipigs were assigned into three groups of six animals and euthanised after one month (T1), two months (T2), and four months (T3), respectively. Each maxillary sinus was randomly allocated to either test or control with an equal volume of graft. Computed tomography scans (CTs) after MSFA (T0) were compared with CTs after euthanasia to evaluate graft volume (GV) changes and bone density (BD) using three-dimensional measurements and Hounsfield units. GV was larger in test compared with control at T1 (P = 0.046), whereas GV was larger in control compared with test at T3 (P = 0.01). BD increased from T0 to T1-T3 (P < 0.001) with both treatments. Higher BD was observed in control compared with test at T3 (P = 0.01), while no significant difference was observed at T1 and T2. Conclusively, the present study demonstrate that allogeneic ASCs seeded on DBBM in conjunction with MSFA seemed not to improve the radiographic outcome compared with excipient on DBBM. However, radiological outcomes need to be supplemented by bone histomorphometry before definitive conclusions can be provided about the beneficial use of allogeneic ASCs seeded on DBBM in conjunction with MSFA compared with DBBM alone.

Clinical and patient-reported outcomes of tissue engineering strategies for periodontal and peri-implant reconstruction

Scientific advancements in biomaterials, cellular therapies, and growth factors have brought new therapeutic options for periodontal and peri-implant reconstructive procedures. These tissue engineering strategies involve the enrichment of scaffolds with living cells or signaling molecules and aim at mimicking the cascades of wound healing events and the clinical outcomes of conventional autogenous grafts, without the need for donor tissue. Several tissue engineering strategies have been explored over the years for a variety of clinical scenarios, including periodontal regeneration, treatment of gingival recessions/mucogingival conditions, alveolar ridge preservation, bone augmentation procedures, sinus floor elevation, and peri-implant bone regeneration therapies. The goal of this article was to review the tissue engineering strategies that have been performed for periodontal and peri-implant reconstruction and implant site development, and to evaluate their safety, invasiveness, efficacy, and patient-reported outcomes. A detailed systematic search was conducted to identify eligible randomized controlled trials reporting the outcomes of tissue engineering strategies utilized for the aforementioned indications. A total of 128 trials were ultimately included in this review for a detailed qualitative analysis. Commonly performed tissue engineering strategies involved scaffolds enriched with mesenchymal or somatic cells (cell-based tissue engineering strategies), or more often scaffolds loaded with signaling molecules/growth factors (signaling molecule-based tissue engineering strategies). These approaches were found to be safe when utilized for periodontal and peri-implant reconstruction therapies and implant site development. Tissue engineering strategies demonstrated either similar or superior clinical outcomes than conventional approaches for the treatment of infrabony and furcation defects, alveolar ridge preservation, and sinus floor augmentation. Tissue engineering strategies can promote higher root coverage, keratinized tissue width, and gingival thickness gain than scaffolds alone can, and they can often obtain similar mean root coverage compared with autogenous grafts. There is some evidence suggesting that tissue engineering strategies can have a positive effect on patient morbidity, their preference, esthetics, and quality of life when utilized for the treatment of mucogingival deformities. Similarly, tissue engineering strategies can reduce the invasiveness and complications of autogenous graft-based staged bone augmentation. More studies incorporating patient-reported outcomes are needed to understand the cost-benefits of tissue engineering strategies compared with traditional treatments.

Advances in Tissue Engineering and Implications for Oral and Maxillofacial Reconstruction

BACKGROUND

Reconstructive surgery in the oral and maxillofacial region poses many challenges due to the complexity of the facial skeleton and the presence of composite defects involving soft tissue, bone and nerve defects.

METHODS

Current methods of reconstruction include autologous grafting techniques with local or regional rotational flaps or microvascular free flaps, allografts, xenografts and prosthetic devices.

RESULTS

Tissue engineering therapies utilizing stem cells provide promise for enhancing the current reconstructive options.

CONCLUSIONS

This article is a review on tissue engineering strategies applicable to specialists who treat oral and maxillofacial defects.

PRACTICAL IMPLICATIONS

We review advancements in hard tissue regeneration for dental rehabilitation, soft tissue engineering, nerve regeneration and innovative strategies for reconstruction of major defects.

A comparative evaluation of bone regeneration using mesenchymal stem cells versus blood coagulum in sinus augmentation procedures

Objective:

The present study evaluated the quality and quantity of new bone formation in the maxillary sinus lift procedures and stability of implants in posterior atrophic maxilla.

Materials and Methods:

This prospective randomized controlled split-mouth study included 20 patients (16 males and 4 females having a mean age of 36.7 years) having atrophic maxilla. They were divided randomly into two groups: Group A using mesenchymal stem cells and Group B into blood coagulum. They were radiographically evaluated using cone-beam computed tomography (CBCT) for residual bone height preoperatively and availability of new bone formation around implants, density, and stability of implants 6 months postoperatively.

Results:

The placement of dental implants in posterior maxilla is challenging due to rapid resorption of alveolar bone after extraction of teeth due to pneumatization of maxillary sinuses. In both the groups, more pain and swelling were observed in the 2^nd postoperative day which gradually decreased over a period of 7 days. Membrane perforation occurs in only four cases (20%). A significant gain in alveolar bone height was observed in Group A (7.69 mm ± 2.5 mm) and Group B (9.32 mm ± 2 mm) after 6 months. On comparing both the groups, there is a similar significant increase in bone density in Hounsfield units postoperatively at various levels buccally and palatally. Total 40 sinuses were lifted and 42 implants were placed, respectively. All implants showed primary stability.

Conclusions:

Such findings provide a significant contribution in future perspective studies that the use of stem cells had the same success rate as blood coagulum.

Characteristics and biologic effects of thermosensitive quercetin-chitosan/collagen hydrogel on human periodontal ligament stem cells

Thermosensitive hydrogels could function as scaffolds and delivery vehicle of natural flavonoids. The current study aimed to investigate effects of chitosan/collagen ratios on properties of thermosensitive beta-glycerophosphate (bGP) chitosan/collagen hydrogels as delivery vehicle of quercetin and then examined effects of quercetin-hydrogels on growth and cell viability of human periodontal ligament stem cells (hPDLSCs). Microstructure and physical, mechanical and antioxidant properties and quercetin release profiles of the hydrogels were investigated. Fourier transform infrared spectroscopy and X-ray powder diffraction analyses were performed to examine gelation process of the hydrogels. Antioxidant assays were conducted to measure antioxidant capacity of quercetin-hydrogels. It was found that bGP-chitosan/collagen hydrogels exhibited porous structures with interconnected pore architecture and could sustain quercetin release. Chitosan content improved well defined porous structure, increased porosity of the hydrogels and decreased releasing rate of quercetin from the hydrogels. The quercetin-bGP-2:1 (wt/wt) chitosan/collagen hydrogels exhibited antioxidant capacity and were able to promote growth of hPDLSCs in a dose dependent manner. In conclusion, the thermosensitive quercetin-bGP-2:1 (wt/wt) chitosan/collagen hydrogel demonstrated optimal properties of scaffolds for bone tissue engineering and sustained release of natural flavonoids. Incorporating quercetin in the chitosan/collagen hydrogel enhanced bioactive microenvironment that supported stem cell encapsulation.

Implant Placement Following Crestal Sinus Lift with Sequential Drills and Osteotomes: Five Years after Final Loading Results from a Retrospective Study

The aim of this retrospective study was to clinically evaluate the five-year outcomes of implants placed following a combined approach to the sinus, consisting of sequential drills and osteotomes. Medical records of patients with implants placed in combination with crestal sinus lift using sequential drills and osteotomes, with a residual alveolar bone crest between 4 to 8 mm, and a follow-up of at least five years after final loading, were evaluated. Outcomes were implant and prosthetic survival and success rates, any complication, and marginal bone loss. Data from 96 patients (53 women and 43 men; mean age 54.7 years; range 23-79 years) were collected. A total of 105 single implants were analyzed. After five years of function, two implants were lost and two prostheses failed. No major biological or prosthetic complications occurred. At the five-year examination, the marginal bone loss was 1.24 ± 0.28 mm. Within the limitations of this retrospective study it can be concluded that implants placed following a combined approach to the sinus consisting of sequential drills and osteotomes seem to be a viable option for the treatment of posterior atrophic edentulous maxilla.

Promoting Osseointegration of Dental Implants in Dog Maxillary Sinus Floor Augmentation Using Dentin Matrix Protein 1-Transduced Bone Marrow Stem Cells

BACKGROUND

Beta-tricalcium phosphate (β-TCP) has been employed successfully as a synthetic graft material in maxillary sinus floor augmentation (MSFA) for placing dental implants. However, the lack of osteogenic and osteoinductive properties of this substitute invariably results in bone regeneration of low quality and quantity. The purpose of this study was to determine whether loading dentin matrix protein-1 (DMP1) gene-modified bone marrow mesenchymal stem cells (BMSCs) onto β-TCP promoted bone regeneration and osteointegration of dental implants in MSFA of dogs.

METHODS

BMSCs were transduced with a lentiviral vector overexpressing the DMP1 gene (Lenti-DMP1) and with a lentiviral vector overexpressing enhanced green fluorescent protein (Lenti-EGFP) in vitro and were loaded into β-TCP scaffolds for autologous sinus grafting. Beagles received bilateral MSFA with four biomaterials (① Lenti-DMP1-transduced BMSCs/β-TCP, ② Lenti-EGFP-transduced BMSCs/β-TCP, ③ BMSCs/β-TCP, ④ β-TCP) and simultaneous implant placement at each sinus. Twelve weeks post operation, the maxillae were explanted, and every sinus was evaluated by radiographic observation, micro-CT and histological analysis. The osteogenic outcomes of bone regeneration and osseointegration were compared between the four groups.

RESULTS

The sinuses grafted with Lenti-DMP1-transduced BMSCs/β-TCP constructs presented a significantly higher increase in compact radiopaque area, higher local bone mineral densities, greater bone-implant contact and greater bone density when compared to other three groups.

CONCLUSION

These results demonstrated that combinations of β-TCP and DMP1 gene-modified BMSCs could be used to construct tissue-engineered bone to enhance mineralization of the regenerated bone and osseointegration of dental implants in MSFA.