Mesenchymal stem cells in oral reconstructive surgery: a systematic review of the literature

Bone Tissue Engineering (BTE) of the Craniofacial Skeleton, Part II: Translational Potential of 3D-Printed Scaffolds for Defect Repair

Computer-aided design/computer-aided manufacturing and 3-dimensional (3D) printing techniques have revolutionized the approach to bone tissue engineering for the repair of craniomaxillofacial skeletal defects. Ample research has been performed to gain a fundamental understanding of the optimal 3D-printed scaffold design and composition to facilitate appropriate bone formation and healing. Benchtop and preclinical, small animal model testing of 3D-printed bioactive ceramic scaffolds augmented with pharmacological/biological agents have yielded promising results given their potential combined osteogenic and osteoinductive capacity. However, other factors must be evaluated before newly developed constructs may be considered analogous alternatives to the "gold standard" autologous graft for defect repair. More specifically, the 3D-printed bioactive ceramic scaffold's long-term safety profile, biocompatibility, and resorption kinetics must be studied. The ultimate goal is to successfully regenerate bone that is comparable in volume, density, histologic composition, and mechanical strength to that of native bone. In vivo studies of these newly developed bone tissue engineering in translational animal models continue to make strides toward addressing regulatory and clinically relevant topics. These include the use of skeletally immature animal models to address the challenges posed by craniomaxillofacial defect repair in pediatric patients. This manuscript reviews the most recent preclinical animal studies seeking to assess 3D-printed ceramic scaffolds for improved repair of critical-sized craniofacial bony defects.

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.

An Up-To-Date Overview of Dental Tissue Regeneration Using Dental Origin Mesenchymal Stem Cells: Challenges and Road Ahead

Stem cells (SCs) research has experienced exponential growth in recent years. SC-based treatments can enhance the lives of people suffering from cardiac ischemia, Alzheimer’s disease, and regenerative drug conditions, like bone or loss of teeth. Numerous kinds of progenitor/SCs have been hypothesized to depend on their potential to regain and/or heal wounded tissue and partly recover organ function. Growing data suggest that SCs (SCs) are concentrated in functions and that particular tissues have more SCs. Dental tissues, in particular, are considered a significant cause of mesenchymal stem cells (MSCs) cells appropriate for tissue regeneration uses. Tissue regeneration and SCs biology have particular attention in dentistry because they may give a novel method for creating clinical material and/or tissue redevelopment. Dental pulp, dental papilla, periodontal ligament, and dental follicle contain mesenchymal SCs. Such SCs, which must be identified and cultivated in specific tissue culture environments, may be used in tissue engineering applications such as tooth tissue, nerve regeneration, and bone redevelopment. A new cause of SCs, induced pluripotent SCs, was successfully made from human somatic cells, enabling the generation of the patient and disease-specific SCs. The dental SC’s (DSCs) multipotency, rapid proliferation rate, and accessibility make it an ideal basis of MSC for tissue redevelopment. This article discusses current advances in tooth SC investigation and its possible application in tissue redevelopment.

Stem Cell Therapy in Chronic Periodontitis: Host Limitations and Strategies

The treatment of chronic periodontitis is undergoing a transition from simple plaque removal and replacement with substitute materials to regenerative therapy, in which stem cells play an important role. Although stem cell-based periodontal reconstruction has been widely explored, few clinical regeneration studies have been reported. The inflammatory lesions under the impact of host factors such as local microbial–host responses, may impede the regenerative properties of stem cells and destroy their living microenvironment. Furthermore, systemic diseases, in particular diabetes mellitus, synergistically shape the disordered host-bacterial responses and exacerbate the dysfunction of resident periodontal ligament stem cells (PDLSCs), which ultimately restrain the capacity of mesenchymal stromal cells (MSCs) to repair the damaged periodontal tissue. Accordingly, precise regulation of an instructive niche has become a promising approach to facilitate stem cell-based therapeutics for ameliorating periodontitis and for periodontal tissue regeneration. This review describes host limitations and coping strategies that influence resident or transplanted stem cell-mediated periodontal regeneration, such as the management of local microbial–host responses and rejuvenation of endogenous PDLSCs. More importantly, we recommend that active treatments for systemic diseases would also assist in recovering the limited stem cell function on the basis of amelioration of the inflammatory periodontal microenvironment.

Oral biosciences: The annual review 2020

BACKGROUND

The Journal of Oral Biosciences is devoted to the advancement and dissemination of fundamental knowledge concerning every aspect of oral biosciences.

HIGHLIGHT

This review featured the review articles in the fields of "Microbiology," "Palate," "Stem Cells," "Mucosal Diseases," "Bone Cell Biology," "MicroRNAs," "TRPV1 Cation Channels," and "Interleukins" in addition to the review article by prize-winners of the "Rising Members Award" ("DKK3 expression and function in head and neck squamous cell carcinoma and other cancers"), presented by the Japanese Association for Oral Biology.

CONCLUSION

These reviews in the Journal of Oral Biosciences have inspired the readers of the journal to broaden their knowledge regarding the various aspects of oral biosciences. The current editorial review introduces these exciting review articles.

Usage of stem cells in oral and maxillofacial region

Malformations of the maxillofacial region has disturbing psychosocial effects and causes enormous socioeconomic concerns. The management of maxillofacial defects caused by congenital anomalies, trauma, osteoporotic fractures, periodontitis, or cancer treatment is challenging for oral and maxillofacial surgeons. Numerous approaches have been recommended for the managing of these deficiencies. The traditional treatment for maxillofacial defects or their repair is an intricate process by autologous bone grafts from the scapula, ribs, fibula, or iliac crest origins. Regenerative medicine is well thought-out as a perfect substitute approach for autologous bone grafts to renovate bone deficiencies. The use of stem cells has improved results and offered a technique to reconstruct craniofacial bone defects. The field of tissue engineering for the regeneration of maxillofacial needs integration of biochemical and biomaterial engineering aspects with cell transplantation to generate better-quality biomimetic scaffolds, prevascularize three-dimensional (3D) tissue structures, and engineer the composite interface of diverse facial tissues. In this review, we have discussed the application of different adult stem cells to repair oral and maxillofacial defects in animal models and clinical trials.

Efficacy of stem cell allograft in maxillary sinus bone regeneration: a randomized controlled clinical and blinded histomorphometric study

Purpose

This study aimed to evaluate the quality and quantity of newly generated bone in the maxillary sinus grafted with stem cell-based allograft material.

Methods

This study was a single site, prospective, blinded, randomized, and controlled clinical trial. Eleven subjects with 18 edentulous posterior maxillary sites requiring sinus augmentation for delayed implant placement using a lateral window approach were enrolled. At the time of sinus augmentation, test sinus was grafted with stem cell-based allograft (Osteocel Plus; NuVasive Therapeutics), while the control sinus was grafted with conventional cortico-cancellous allograft (alloOss; ACE Surgical). Cone beam computer tomography (CBCT) scan was taken before and 14 weeks post-sinus augmentation procedure, i.e., 2 weeks before implant placement. Thirty-six trephined core bone biopsies were harvested from the anterior and posterior grafted lateral-window osteotomy sites at the time of implant placement.

Results

The results showed a statistically significant difference in the vital bone percentage between the test and the control groups at the posterior grafted sites (p = 0.03). There was no significant difference in the percentage of vital bone between the anterior and posterior grafted sites within the test and control groups (p > .05). The CBCT analysis showed that the maxillary sinuses at the posterior grafted sites were statistically wider than those at the anterior grafted sites in both groups (p < .05).

Conclusions

Different allograft bone materials can be used in the maxillary sinus augmentation procedures. Stem cell allograft has more osteogenic potential with a better outcome in the wide posterior sinus.

Mesenchymal stem cells and biologic factors leading to bone formation

BACKGROUND

Physiological bone formation and bone regeneration occurring during bone repair can be considered distinct but similar processes. Mesenchymal stem cells (MSC) and associated biologic factors are crucial to both bone formation and bone regeneration.

AIM

To perform a narrative review of the current literature regarding the role of MSC and biologic factors in bone formation with the aim of discussing the clinical relevance of in vitro and in vivo animal studies.

METHODS

The literature was searched for studies on MSC and biologic factors associated with the formation of bone in the mandible and maxilla. The search specifically targeted studies on key aspects of how stem cells and biologic factors are important in bone formation and how this might be relevant to bone regeneration. The results are summarized in a narrative review format.

RESULTS

Different types of MSC and many biologic factors are associated with bone formation in the maxilla and mandible.

CONCLUSION

Bone formation and regeneration involve very complex and highly regulated cellular and molecular processes. By studying these processes, new clinical opportunities will arise for therapeutic bone regenerative treatments.

Risk factors in bone augmentation procedures

Bone augmentation is an extremely common procedure in implant dentistry today because of significant advancements with reactive biomaterials, a better understanding of the mechanism of action that is found with growth factors contained in platelets, and improvements in surgical techniques. The expectation is for the surgeon to place the dental implant in the position that best serves the requirements of the prosthetic restorations. With the increasing demands that patients have for ideal prosthetic results, surgeons are expected to predictably augment both hard and soft tissues to provide the anticipated esthetic and functional outcomes. Bone grafting can be performed before, during, and after the implant placement; however, these augmentation procedures come with increased cost, the risk of complications such as infection or failure, and lengthening of the total treatment time. In addition, a plethora of grafting materials are available commercially, where they are often inadequately studied, or there is minimal information regarding their predictability or long-term success, or ability to support dental implants. It is clear that although the surgical field has seen major progress since early implant surgical techniques in the 1980s, major challenges still exist with hard tissue augmentation procedures. This review will discuss these challenges that are increased and often specific to bone graft healing, and which are becoming more common as implant site development often requires bone augmentation to improve volume or contour deficiencies. The risk factors that patients may present with that will affect outcomes with bone augmentation procedures are identified, and recommendations for the prevention of complications or managing complications once they have occurred are provided.

Stem Cells in Dentistry: Types of Intra- and Extraoral Tissue-Derived Stem Cells and Clinical Applications

Stem cells are undifferentiated cells, capable of renewing themselves, with the capacity to produce different cell types to regenerate missing tissues and treat diseases. Oral facial tissues have been identified as a source and therapeutic target for stem cells with clinical interest in dentistry. This narrative review report targets on the several extraoral- and intraoral-derived stem cells that can be applied in dentistry. In addition, stem cell origins are suggested in what concerns their ability to differentiate as well as their particular distinguishing quality of convenience and immunomodulatory for regenerative dentistry. The development of bioengineered teeth to replace the patient's missing teeth was also possible because of stem cell technologies. This review will also focus our attention on the clinical application of stem cells in dentistry. In recent years, a variety of articles reported the advantages of stem cell-based procedures in regenerative treatments. The regeneration of lost oral tissue is the target of stem cell research. Owing to the fact that bone imperfections that ensue after tooth loss can result in further bone loss which limit the success of dental implants and prosthodontic therapies, the rehabilitation of alveolar ridge height is prosthodontists' principal interest. The development of bioengineered teeth to replace the patient's missing teeth was also possible because of stem cell technologies. In addition, a “dental stem cell banking” is available for regenerative treatments in the future. The main features of stem cells in the future of dentistry should be understood by clinicians.

Stem Cells of Dental Origin: Current Research Trends and Key Milestones towards Clinical Application

Dental Mesenchymal Stem Cells (MSCs), including Dental Pulp Stem Cells (DPSCs), Stem Cells from Human Exfoliated Deciduous teeth (SHED), and Stem Cells From Apical Papilla (SCAP), have been extensively studied using highly sophisticated in vitro and in vivo systems, yielding substantially improved understanding of their intriguing biological properties. Their capacity to reconstitute various dental and nondental tissues and the inherent angiogenic, neurogenic, and immunomodulatory properties of their secretome have been a subject of meticulous and costly research by various groups over the past decade. Key milestone achievements have exemplified their clinical utility in Regenerative Dentistry, as surrogate therapeutic modules for conventional biomaterial-based approaches, offering regeneration of damaged oral tissues instead of simply “filling the gaps.” Thus, the essential next step to validate these immense advances is the implementation of well-designed clinical trials paving the way for exploiting these fascinating research achievements for patient well-being: the ultimate aim of this ground breaking technology. This review paper presents a concise overview of the major biological properties of the human dental MSCs, critical for the translational pathway “from bench to clinic.”

Concise Review: Mesenchymal Stem Cell Therapy for Pediatric Disease: Perspectives on Success and Potential Improvements

Mesenchymal stem cells (MSCs) represent a potentially revolutionary therapy for a wide variety of pediatric diseases, but the optimal cell-based therapeutics for such diversity have not yet been specified. The published clinical trials for pediatric pulmonary, cardiac, orthopedic, endocrine, neurologic, and hematologic diseases provide evidence that MSCs are indeed efficacious, but the significant heterogeneity in therapeutic approaches between studies raises new questions. The purpose of this review is to stimulate new preclinical and clinical trials to investigate these factors. First, we discuss recent clinical trials for pediatric diseases studying MSCs obtained from bone marrow, umbilical cord and umbilical cord blood, placenta, amniotic fluid, and adipose tissue. We then identify factors, some unique to pediatrics, which must be examined to optimize therapeutic efficacy, including route of administration, dose, timing of administration, the role of ex vivo differentiation, cell culture techniques, donor factors, host factors, and the immunologic implications of allogeneic therapy. Finally, we discuss some of the practicalities of bringing cell-based therapy into the clinic, including regulatory and manufacturing considerations. The aim of this review is to inform future studies seeking to maximize therapeutic efficacy for each disease and for each patient. Stem Cells Translational Medicine 2017;6:539-565.

Mandibular Tissue Engineering: Past, Present, Future

Almost 2 decades ago, the senior author's (M.T.J.) first article was with our mentor, Dr Leonard B. Kaban, a review article titled "Distraction Osteogenesis: Past, Present, Future." In 1998, many thought it would be impossible to have a remotely activated, small, curvilinear distractor that could be placed using endoscopic techniques. Currently, a U.S. patent for a curvilinear automated device and endoscopic techniques for minimally invasive access for jaw reconstruction exist. With minimally invasive access for jaw reconstruction, the burden to decrease donor site morbidity has increased. Distraction osteogenesis (DO) is an in vivo form of tissue engineering. The DO technique eliminates a donor site, is less invasive, requires a shorter operative time than usual procedures, and can be used for multiple reconstruction applications. Tissue engineering could further reduce morbidity and cost and increase treatment availability. The purpose of the present report was to review our experience with tissue engineering of bone: the past, present, and our vision for the future. The present report serves as a tribute to our mentor and acknowledges Dr Kaban for his incessant tutelage, guidance, wisdom, and boundless vision.

Treatment of Peri-Implant Defects in the Rabbit's Tibia with Adipose or Bone Marrow-Derived Mesenchymal Stems Cells

BACKGROUND

Mesenchymal stem cell (MSC) treatment in conjunction with bone graft materials or space filler can be an alternative to autogenous bone grafts in the treatment of peri-implant bone defects.

PURPOSE

To evaluate the success of bone regeneration capacity of adipose-derived and bone marrow-derived MSCs for the treatment of peri-implant bone defects when applied with a beta-tricalcium phosphate/collagen-based scaffold.

MATERIAL AND METHODS

Forty implants were placed into the tibiae of 10 rabbits bilaterally. Surgical defects created around the implants were treated with one the following treatment modalities: 1) adipose-derived MSC transplanted scaffold + collagen membrane; 2) bone marrow-derived MSC transplanted scaffold + collagen membrane; 3) autogenous bone + collagen membrane; and 4) collagen membrane only. The bone regeneration capacity of each technique was determined by histomorphometry, micro-CT, and measuring the implant stability by resonance frequency analysis.

RESULTS

One limb of one rabbit was excluded because of fracture, and another limb was excluded because of infection. All parameters on 36 implants revealed that both sources of MSC can form equivalently new bone that is comparable with autogenous bone. The defects treated with membrane only had significantly less bone formation compared with other groups.

CONCLUSION

Both adipose-derived and bone marrow-derived MSC treatments are feasible alternatives to autogenous bone grafts in the treatment of peri-implant osseos defects.

Skeletal tissue engineering using mesenchymal or embryonic stem cells: clinical and experimental data

INTRODUCTION

Mesenchymal stem cells (MSCs) can be obtained from a wide variety of tissues for bone tissue engineering such as bone marrow, adipose, birth-associated, peripheral blood, periosteum, dental and muscle. MSCs from human fetal bone marrow and embryonic stem cells (ESCs) are also promising cell sources.

AREAS COVERED

In vitro, in vivo and clinical evidence was collected using MEDLINE® (1950 to January 2014), EMBASE (1980 to January 2014) and Google Scholar (1980 to January 2014) databases.

EXPERT OPINION

Enhanced results have been found when combining bone marrow-derived mesenchymal stem cells (BMMSCs) with recently developed scaffolds such as glass ceramics and starch-based polymeric scaffolds. Preclinical studies investigating adipose tissue-derived stem cells and umbilical cord tissue-derived stem cells suggest that they are likely to become promising alternatives. Stem cells derived from periosteum and dental tissues such as the periodontal ligament have an osteogenic potential similar to BMMSCs. Stem cells from human fetal bone marrow have demonstrated superior proliferation and osteogenic differentiation than perinatal and postnatal tissues. Despite ethical concerns and potential for teratoma formation, developments have also been made for the use of ESCs in terms of culture and ideal scaffold.

Osteogenic Potential of Dental Mesenchymal Stem Cells in Preclinical Studies: A Systematic Review Using Modified ARRIVE and CONSORT Guidelines

Background and Objective. Dental stem cell-based tissue engineered constructs are emerging as a promising alternative to autologous bone transfer for treating bone defects. The purpose of this review is to systematically assess the preclinical in vivo and in vitro studies which have evaluated the efficacy of dental stem cells on bone regeneration. Methods. A literature search was conducted in Ovid Medline, Embase, PubMed, and Web of Science up to October 2014. Implantation of dental stem cells in animal models for evaluating bone regeneration and/or in vitro studies demonstrating osteogenic potential of dental stem cells were included. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used to ensure the quality of the search. Modified ARRIVE (Animal research: reporting in invivo experiments) and CONSORT (Consolidated reporting of trials) were used to critically analyze the selected studies. Results. From 1914 citations, 207 full-text articles were screened and 137 studies were included in this review. Because of the heterogeneity observed in the studies selected, meta-analysis was not possible. Conclusion. Both in vivo and in vitro studies indicate the potential use of dental stem cells in bone regeneration. However well-designed randomized animal trials are needed before moving into clinical trials.

Key aspects on the use of bone substitutes for bone regeneration of edentulous ridges

OBJECTIVES

To review the histological and clinical outcomes of the use of bone substitues in different oral bone regenerative procedures: socket preservation, immediate implant placement, lateral and vertical bone augmentation.

METHODS

Histological animal studies and clinical trials regarding the performances of bone substitutes, either allogenic, xenogeneic or alloplastic, have been evaluated. Different procedures examined separately and evidence-based results were provided.

RESULTS

The use of deproteinized bovine bone mineral (DBBM) seems to be effective most clinical indications, due to their osteoconductivity, space maintenance characteristics and slow resorption. The combination of Hydroxyapatite and Beta Tricalcium Phospate (HA/TCP) has also reported similar histological evidence and clinical outcomes. The use of autogenous block grafts is still the method of choice in clinical situations in need of vertical bone augmentation.

CONCLUSIONS

The use of bone substitutes is the standard of therapy in current modalities of lateral bone augmentation, mainly when used in conjunction with implant placement.

Secreted adiponectin as a marker to evaluate in vitro the adipogenic differentiation of human mesenchymal stromal cells

BACKGROUND AIMS

Multipotency is one of the hallmarks of mesenchymal stromal cells (MSCs). Given the widespread adoption of MSC-based clinical applications, the need for rapid and reliable methods to estimate MSC multipotency is demanding. Adipogenic potential is commonly evaluated by staining cell lipid droplets with oil red O. This cytochemical assay is performed at the terminal stage of adipogenic induction (21-28 days) and necessitates the destruction of the specimen. In this study, we investigated whether it is possible to assess MSC adipogenic differentiation in a more efficient, timely and non-destructive manner, while monitoring in vitro secretion of adiponectin, a hormone specifically secreted by adipose tissue.

METHODS

A commercially available enzyme-linked immunosorbent assay kit was used to quantify adiponectin secreted in the culture medium of adipo-induced human bone marrow-derived MSCs. Oil red O staining was used as a reference method.

RESULTS

Adiponectin is detectable after 10 days of induction at a median concentration of 5.13 ng/mL. The secretion of adiponectin steadily increases as adipogenesis proceeds. Adiponectin is undetectable when adipogenic induction is pharmacologically blocked, inefficient or when human MSCs are induced to differentiate toward the osteogenic lineage, proving the specificity of the assay. Furthermore, the results of adiponectin secretion strongly correlate with oil red O quantification at the end of induction treatment.

CONCLUSIONS

Our results demonstrate that quantification of secreted adiponectin can be used as a reliable and robust method to evaluate adipogenic potential without destroying samples. This method provides a useful tool for quality control in the laboratory and in clinical applications of human MSCs.