Bone Engineering of Maxillary Sinus Bone Deficiencies Using Enriched CD90+ Stem Cell Therapy: A Randomized Clinical Trial

Dual-Functional Peptide DPI-VTK Promotes Mesenchymal Stem Cell Migration for Bone Regeneration

Targeting specific populations of host cells with chemotactic and adhesion factors is a promising strategy for inducing bone regeneration without the use of exogenous cells. Two peptide sequences have been derived from phage display: the mesenchymal stem cell (MSC) binding DPI (DPIYALSWSGMA) sequence and the apatite binding VTK (VTKHLNQISQSY) sequence. When combined into the dual-functional sequence, DPI-VTK increases the adhesion strength of MSCs to apatite surfaces and the amount of bone formation with transplanted MSCs. Because many adhesion molecules can stimulate chemotaxis, and cell adhesion to peptide DPI-VTK is mediated by integrins also critical to migration, we hypothesized that DPI-VTK serves as an MSC-specific chemotactic factor and can increase bone regeneration by promoting the osteogenesis of the migrated host MSCs in vivo. In transwell assays, induced pluripotent stem cell-derived human MSCs (p < 0.0001) and primary mouse calvarial cells (p < 0.0001) showed significantly increased migration in vitro when DPI-VTK was used as a chemoattractant. Further characterization of DPI-VTK binding cells from mouse calvaria using flow cytometry showed specificity toward cells expressing MSC markers (CD29, CD73, CD90, CD105, CD106, Sca-1, CD44, and CD200). When conjugated to a mineralized scaffold in vivo, DPI-VTK increased the migration of CD90 and CD200 positive cells (p < 0.05) and increased bone formation versus no-peptide controls (p < 0.05). These results demonstrate the utility of phage display in creating multifunctional peptides that can increase migration, adhesion, and bone formation in vivo, a strategy that could be applied to numerous different cell types and systems. Results advance biomaterials-based bone regeneration in two ways-demonstrating the ability of the phage-derived peptides to increase the migration of MSCs in vivo and increase host-mediated bone regeneration-potentially bypassing cell transplantation.

Identification of mesenchymal stem cell populations with high osteogenic potential using difference in cell division rate

Introduction

In bone regenerative medicine, mesenchymal stem cells (MSCs) have been widely investigated for their potential in bone regeneration. However, MSCs are a heterogeneous cell population containing a variety of cell types, making it difficult to obtain a homogeneous MSC population sufficient for tissue regeneration. Our group previously reported that by selecting rapidly dividing human auricular chondrocytes, it was possible to enrich for more chondrogenic cells. In this study, we aimed to identify a highly osteogenic MSC population by using a similar approach for mouse bone marrow MSCs.

Methods

Mouse bone marrow MSCs were fluorescently labeled with carboxyfluorescein succinimidyl ester (CFSE) and sorted according to the fluorescence intensity using flow cytometry on day 3 after labeling. To compare the ability to produce bone matrix in vitro, osteogenic differentiation cultures were performed and mineral deposition was confirmed by alizarin red staining. Real-time qPCR was also performed to examine the differences in gene expression between the fast- and slow-dividing cell groups immediately after aliquoting and after osteogenic differentiation.

Results

Differences in the growth rate of the fractionated cells were maintained after culture. Results of osteogenic differentiation culture and alizarin red staining showed more extensive mineral deposition in the slow cell group than in the fast cell group. Calcium quantification also showed higher absorbance in the slow cell group compared to the fast cell group, indicating higher osteogenic differentiation potential in the slow cell group. Furthermore, real-time qPCR analysis showed that osteocalcin expression was higher in the slow cell group in cells immediately after preparative differentiation. In addition, the expression of osteocalcin and sclerostin were higher in the slow cells after osteogenic differentiation.

Conclusion

The slow cell population contains many highly differentiated cells that are already more deeply committed to the bone lineage, suggesting that they have higher osteogenic differentiation potential than the fast cell population. This study will contribute to the realization of better bone regenerative medicine by utilizing the high osteogenic differentiation potential of the slow cell population.

Histomorphometric outcome following sinus floor augmentation with allogeneic adipose tissue-derived stem cells. A randomized controlled experimental study

The aim of this pre-clinical study was to test the hypothesis of no difference in histomorphometric outcome following sinus floor augmentation (SFA) with allogeneic adipose tissue-derived stem cells (AASCs) seeded on deproteinized bovine bone mineral (DBBM) (test) compared with excipient on DBBM (control). Eighteen minipigs were allocated into three groups of six animals and euthanised after one month (T1), two months (T2), and four months (T3). The sinuses of each animal were randomly assigned to either test or control with identical graft volume. Percentage of newly formed bone (NFB), non-mineralized tissue, residual DBBM, and bone-to-implant contact (BIC) were estimated by histomorphometric analysis in a randomly selected region of interest and summarized as mean percentage with 95% confidence interval. Test group, mean percentage of NFB and BIC was 8.8 and 19.5 (T1), 17.7 and 23.2 (T2), 37.1 and 30.4 (T3). Control group, corresponding values were 8.9 and 13.9 (T1), 18.7 and 23.3 (T2), 36.8 and 36.6 (T3). There were no significant differences in NFB or BIC at T1 (P = 0.964; 0.551), T2 (P = 0.927; 0.992), and T3 (P = 0.971; 0.557) between test or control. Percentage of NFB was significantly higher at T3 compared with T1, in test (P = 0.001) and control (P = 0.004), while no significant difference in BIC was disclosed between T1, T2, and T3, in test and control, respectively. In conclusion, adding AASCs to DBBM seem not to improve NFB or BIC compared with DBBM alone in conjunction with SFA.

Extracellular Vesicles-in-Hydrogel (EViH) targeting pathophysiology for tissue repair

Regenerative medicine endeavors to restore damaged tissues and organs utilizing biological approaches. Utilizing biomaterials to target and regulate the pathophysiological processes of injured tissues stands as a crucial method in propelling this field forward. The Extracellular Vesicles-in-Hydrogel (EViH) system amalgamates the advantages of extracellular vesicles (EVs) and hydrogels, rendering it a prominent biomaterial in regenerative medicine with substantial potential for clinical translation. This review elucidates the development and benefits of the EViH system in tissue regeneration, emphasizing the interaction and impact of EVs and hydrogels. Furthermore, it succinctly outlines the pathophysiological characteristics of various types of tissue injuries such as wounds, bone and cartilage injuries, cardiovascular diseases, nerve injuries, as well as liver and kidney injuries, underscoring how EViH systems target these processes to address related tissue damage. Lastly, it explores the challenges and prospects in further advancing EViH-based tissue regeneration, aiming to impart a comprehensive understanding of EViH. The objective is to furnish a thorough overview of EViH in enhancing regenerative medicine applications and to inspire researchers to devise innovative tissue engineering materials for regenerative medicine.

First Experience of Personalized in Situ Tissue Engineering for Thoracic Surgery of the Sarcoma Patient: MSCs-Containing Minimally Manipulated Cells and an Individualized Micropore Titanium Sternum in a One-Year Follow-Up Case Report

Individually customized grafts have become standard for reconstructing extensive chest wall defects resulting from surgical interventions for sternal malignant neoplasms. However, the outcomes of these graft implantations can be further improved by administering patient-derived cells, which have minimal oncological risks. In 2021, a 52-year-old woman with chondrosarcoma (pT2N0M0G2, stage IIB) was admitted to the Department of Thoracic Surgery. The patient presented with a large tumor in the body of the sternum, measuring 81 × 94 × 91 mm, according to the computed tomography (CT) scan. To address this, an individualized endoprosthesis was modeled and created using the original 'pincer-dock' construction based on CT-scan screens. The mononuclear cell fraction (MNCs) was obtained from the patient's peripheral blood one week before surgery using a Haemonetics cell separation device and cryopreserved until the day of the procedure. The resulting 30 mL MNC suspension contained 12 mln cells per 1 mL. We performed flow cytometry analysis using a FACS Aria III flow cytometer to confirm the presence of mesenchymal stromal cells in the MNCs. We also performed immunostaining for S-100, a common tumor marker for benign and malignant diseases, and D2-40, a marker for the lymphatic endothelium that reacts with Kaposi's sarcoma and a subset of angiosarcomas. None of the cells were positive for either marker. Approximately 3 ml of the MNC suspension was injected into each rib edge and 30 ml into the operating field immediately after resection. The titanium endoprosthesis was placed in the sternal defect, and the body of the endoprosthesis was securely covered with a laparoscopically mobilized omental flap. After a one-year follow-up, the patient showed no signs of recurrence or post-surgical complications. These outstanding functional and cosmetic results highlight the potential for the broader clinical utilization of minimally manipulated cells in personalized medicine in oncology. These results could pave the way for wider clinical application of peripheral blood-derived minimally manipulated cells in personalized medicine as an adjuvant for titanium endoprosthesis reconstruction of osteochondral defects in patients with sarcoma.

Assessing the Impact of Stem Cell-based Therapy on Periodontal Health: A Meta-analysis of Clinical Studies

OBJECTIVE

While clinical trials exploring stem cells for regenerating periodontal tissues have demonstrated positive results, there is a limited availability of systematic literature reviews on this subject. To gain a more comprehensive understanding of stem cell interventions in periodontal regeneration, this meta-analysis is undertaken to assess the beneficial effects of stem cells in human periodontal regeneration.

METHODS

"PubMed," "PubMed Central," "Web of Science," "Embase Scopus" "Wanfang," and "CNKI," were used to extract clinical studies related to the utilization of stem cells in repairing periodontal tissue defects. This search included studies published up until October 5, 2023. The inclusion criteria required the studies to compare the efficacy of stem cell-based therapy with stem cell-free therapy for regenerating periodontal tissues. Meta-analysis was conducted using Review Manager software (version 5.4).

RESULTS

This meta-analysis synthesized findings from 15 selected studies investigating the impact of stem cell interventions on periodontal tissue regeneration. The "stem cell" group displayed a substantial reduction in clinical attachment level (CAL) compared to the "control" group within 3 to 12 months post-surgery. However, no significant differences in CAL gain were found between groups. Probing pocket depth (PPD) significantly decreased in the "stem cell" group compared to the "control" group, particularly for follow-up periods exceeding 6 months, and dental stem cell treatment exhibited notable improvements. Conversely, no significant differences were observed in PPD reduction. Gingival recession (GR) significantly decreased in the "stem cell" group compared to the "control" group at 3 to 12 months post-surgery. No significant differences were observed in GR reduction between groups. No significant differences were identified in cementoenamel junction-bone distance reduction, infrabony defect reduction, or bone mineral density increase between the two groups. Furthermore, no significant changes were observed in the gingival index, plaque index, or width of keratinized gingiva.

CONCLUSION

In conclusion, while stem cell-based therapy offers promising prospects for periodontal defect treatment, there are notable limitations in the current body of research. Larger, multicenter, double-blind RCTs with robust methodologies are needed to provide more reliable evidence for stem cell-based intervention in periodontitis.

CD90's role in vascularization and healing of rib fractures: insights from Dll4/notch regulation

BACKGROUND

Vascularization after rib fracture is a crucial physiological process that is essential for the repair and healing of the rib. Studies have shown that CD90 plays a critical role in regulating rib fracture healing, but the underlying mechanism of its role has not been fully elucidated.

METHODS

CD90 adenovirus knockout mice were used to construct a rib injury model. The bone healing was observed by micro-CT. CD31/EMCN immunofluorescence staining was performed on bone tissue to observe the density of H-shaped and L-shaped blood vessels at the site of bone injury. CD31 and EMCN dual-stained single cells from the rib fracture sites were detected by flow cytometry. The periosteal stem cells transfected with CD90 or Notch1 overexpression and silencing vector were co-cultured with osteoblast MC3T3-E1 in osteogenic induction medium. Moreover, bone microvascular endothelial cells were extracted from the rib injury and co-cultured with the periosteal stem cells transfected with CD90. CCK-8 was used to detect cell viability, RT-qPCR and Western blot were used to detect Notch1, Notch2, Notch3, Notch4, CD31, HIF-1α, CD90, RUNX2, OCN and OPN expression. Alkaline phosphatase (ALP) staining and alizarin red staining were used to observe mineralized nodules. Immunofluorescence staining was used to detect the expression of Dll4, Notch, and CD90 in each group of cells. The angiogenesis experiment was conducted to observe cellular vascular formation.

RESULTS

Compared with the Adsh-NC group, the bone healing in the Adsh-CD90 group was significantly impaired, with a marked reduction in the number and volume of blood vessels at the rib fracture site, as evidenced by CD31/EMCN immunofluorescence staining, which showed a reduction in the number of H type vessels at the site of bone injury. It was found that CD90 depletion can inhibit the signaling of Dll4/Notch in the rib fracture site. Furthermore, we found that overexpression of Notch1 reverses the impairment of tubule formation in bone microvascular endothelial cells caused by CD90 suppression.r.Dll4 protein reverses the inhibitory effect of CD90 deletion on periosteal stem cells and MC3T3-E1 cell viability and osteogenesis. In the end, we found that overexpression of Notch1 and CD90 can promote angiogenesis of bone microvascular endothelial cells and Notch pathway activation.

CONCLUSION

CD90 can affect vascular formation in mouse rib fractures, and CD90 may be regulated by Dll4/Notch.

The Therapeutic Use of Dental Mesenchymal Stem Cells in Human Clinical Trials

Mesenchymal stem cells (MSCs), characterized by their undifferentiated and multipotent nature, can be derived from various sources, including bone marrow, adipose, and dental tissues. Among these, dental MSCs (DSCs) exhibit universal MSC characteristics and are attracting considerable attention for regenerating oral and craniofacial tissues. This review provides a contemporary overview of recently published clinical studies using DSCs for various orodental and maxillofacial regenerative applications, including bone, periodontal, and endodontic regeneration. It also explores the utilization of DSCs in treating systemic conditions, exemplified by their application in managing conditions such as COVID-19 and osteoarthritis. The available evidence underscores the potential of DSCs and their secretome as efficacious tools in regenerative medicine for both dental and nondental clinical applications, supporting the continued promise of stem cell-based therapies. It is nevertheless evident that there are a number of important challenges that restrict the widespread utilization of DSCs, namely, difficulty in standardizing autologous preparations, insufficient cell surface marker characterization, high production costs, and regulatory compliance requirements. Further, the unique requirements of dental applications, especially complex structures such as the periodontium, where temporospatial control over the healing process is required, necessitate the combination of stem cells with appropriate scaffolds according to the principles of tissue engineering. There is currently insufficient evidence to support the clinical translation of DSCs into clinical practice, and phase 3 clinical trials with standardized protocols for cell sourcing, propagation, dosing, and delivery are required to move the field forward. In summary, this review provides a contemporary overview of the evolving landscape of stem cell therapy, offering insights into the latest developments and trends as well as the challenges that need to be addressed for the widespread application of DSC-based cell therapies.

The Advantages and Shortcomings of Stem Cell Therapy for Enhanced Bone Healing

This review explores the regenerative potential of key progenitor cell types and therapeutic strategies to improve healing of complex fractures and bone defects. We define, summarize, and discuss the differentiation potential of totipotent, pluripotent, and multipotent stem cells, emphasizing the advantages and shortcomings of cell therapy for bone repair and regeneration. The fundamental role of mesenchymal stem cells is highlighted due to their multipotency to differentiate into the key lineage cells including osteoblasts, osteocytes, and chondrocytes, which are crucial for bone formation and remodeling. Hematopoietic stem cells (HSCs) also play a significant role; immune cells such as macrophages and T-cells modulate inflammation and tissue repair. Osteoclasts are multinucleated cells that are important to bone remodeling. Vascular progenitor (VP) cells are critical to oxygen and nutrient supply. The dynamic interplay among these lineages and their microenvironment is essential for effective bone restoration. Therapies involving cells that are more than "minimally manipulated" are controversial and include embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). ESCs, derived from early-stage embryos, possess pluripotent capabilities and have shown promise in preclinical studies for bone healing. iPSCs, reprogrammed from somatic cells, offer personalized medicine applications and can differentiate into various tissue-specific cell lines. Minimally manipulative cell therapy approaches such as the use of bone marrow aspirate concentrate (BMAC), exosomes, and various biomaterials for local delivery are explored for their effectiveness in bone regeneration. BMAC, which contains mostly immune cells but few mesenchymal and VPs, probably improves bone healing by facilitating paracrine-mediated intercellular communication. Exosome isolation harnesses the biological signals and cellular by-products that are a primary source for cell crosstalk and activation. Safe, efficacious, and cost-effective strategies to enhance bone healing using novel cellular therapies are part of a changing paradigm to modulate the inflammatory, repair, and regenerative pathways to achieve earlier more robust tissue healing and improved physical function. Impact Statement Stem cell therapy holds immense potential for bone healing due to its ability to regenerate damaged tissue. Nonmanipulated bone marrow aspirate contains mesenchymal stem cells that promote bone repair and reduce healing time. Induced pluripotent stem cells offer the advantage of creating patient-specific cells that can differentiate into osteoblasts, aiding in bone regeneration. Other delivery methods, such as scaffold-based techniques, enhance stem cell integration and function. Collectively, these approaches can improve treatment outcomes, reduce recovery periods, and advance our understanding of bone healing mechanisms, making them pivotal in orthopedic research and regenerative medicine.

Periodontists and stem cell-based therapy for alveolar bone regeneration: A national survey

BACKGROUND

Stem cell-based therapy for bone regeneration has received attention in medical settings but has not yet been used in clinical practice for treating alveolar bone defects. The objectives of this study were to explore whether periodontists had heard about this approach, and if so how, how interested they were to learn about it, which attitudes and behavioral intentions they had related to using stem cell-based grafting, and what they would like to know before using this approach.

METHODS

Anonymous survey data were collected from 481 members of the American Academy of Periodontology (response rate: 19.41%).

RESULTS

Responses showed 35.3% had heard about stem cell-based therapy, mostly from publications (9.6%) and meetings (8.3%); 76.1% wanted to learn about it through in-person continuing education (CE) courses, 68.6% in online CE courses, and 57.1% from manuals; 73% considered this approach promising; and 54.9% preferred it to traditional approaches. It was important to them that it would result in more bone volume (93%), better bone quality (90.4%), and accelerated healing (83.2%). Also, 60.1% considered it likely/very likely that they would adopt this approach, 54% that patients would prefer it, and 62.1% that it would benefit their practice. When asked what they would like to know about this approach, information about short- and long-term outcomes, cost, and logistical considerations were most frequently named.

CONCLUSIONS

These findings provide the basis to develop educational interventions for periodontists about this novel approach and inform future research activities aimed to translate this approach to clinical practice.

Mesenchymal stem cells in craniofacial reconstruction: a comprehensive review

Craniofacial reconstruction faces many challenges, including high complexity, strong specificity, severe injury, irregular and complex wounds, and high risk of bleeding. Traditionally, the "gold standard" for treating craniofacial bone defects has been tissue transplantation, which involves the transplantation of bone, cartilage, skin, and other tissues from other parts of the body. However, the shape of craniofacial bone and cartilage structures varies greatly and is distinctly different from ordinary long bones. Craniofacial bones originate from the neural crest, while long bones originate from the mesoderm. These factors contribute to the poor effectiveness of tissue transplantation in repairing craniofacial defects. Autologous mesenchymal stem cell transplantation exhibits excellent pluripotency, low immunogenicity, and minimally invasive properties, and is considered a potential alternative to tissue transplantation for treating craniofacial defects. Researchers have found that both craniofacial-specific mesenchymal stem cells and mesenchymal stem cells from other parts of the body have significant effects on the restoration and reconstruction of craniofacial bones, cartilage, wounds, and adipose tissue. In addition, the continuous development and application of tissue engineering technology provide new ideas for craniofacial repair. With the continuous exploration of mesenchymal stem cells by researchers and the continuous development of tissue engineering technology, the use of autologous mesenchymal stem cell transplantation for craniofacial reconstruction has gradually been accepted and promoted. This article will review the applications of various types of mesenchymal stem cells and related tissue engineering in craniofacial repair and reconstruction.

Quantitative analysis of change in bone volume 5 years after sinus floor elevation using plate-shaped bone substitutes: a prospective observational study

PURPOSE

Tricalcium phosphate (TCP) has osteoconductive ability and reportedly offers similar clinical results as autogenous bone grafts in dental implant treatment. However, few reports quantify temporal changes in augmented bone volume after sinus augmentation. We aimed to establish a three-dimensional (3D) quantification method to assess bone volume after sinus augmentation and to evaluate biocompatibility of the TCP plate.

METHODS

Maxillary sinus floor augmentation was performed employing the lateral window technique, and plate-shaped β-TCP (TCP plate) was used instead of granular bone grafting materials. After lifting the sinus membrane, the TCP plate was inserted and supported by dental implants or micro-screws. The changes in bone volumes in the maxillary sinus before and after surgery were recorded using cone-beam computed tomography, saved as Digital Imaging and Communications in Medicine-formatted files, and transformed to Standard Triangle Language (STL)-formatted files. Pre- and post-operative STL data of bone volume were superimposed, and the augmented bone volume was calculated. Moreover, changes in bone volumes, TCP plate resorption rates, and bone heights surrounding the implants were three dimensionally quantified.

RESULTS

Fifteen implants in nine subjects were included in this study. TCP plates secured long-term space making, with results similar to those of granular bone substitutes. Newly formed bone was identified around the implant without bone graft material. TCP plate was absorbed and gradually disappeared.

CONCLUSIONS

A novel 3D quantification method was established to evaluate changes in bone volume. Clinical application of TCP plate in sinus augmentation could be a better procedure in terms of prognosis and safety.

Stem cell therapies for periodontal tissue regeneration: A meta-analysis of clinical trials

Objective

Stem cell therapy in periodontal tissue regeneration has reported optimistic regenerative results; evidence supporting its superiority over conventional methods is still ambiguous. Therefore, this meta-analysis aims to evaluate the therapeutic effects of stem cells in human periodontal regeneration.

Design

A literature search was conducted to retrieve relevant articles on periodontal regeneration in stem cell therapy. A meta-analysis of the studies was conducted using the Stata software.

Results

Fifteen studies that examined the effect of stem cell therapies on periodontal tissue regeneration in 369 patients were selected from databases. Regardless of the various types of cells, both odontogenic (periodontal ligament, dental pulp, gingiva stem cell) and non-odontogenic (bone marrow, periosteum-derived, and umbilical cord stem cells), the cell therapies witnessed significant improvements in terms of clinical attachment level (SMD, -0.67; 95CI, -0.90 to -0.43), probing depth (SMD, -0.76; 95% CI, -1.21 to - 0.31), radiographic intrabony defect depth (SMD, -0.87; 95% CI, -1.52 to -0.23), and histomorphometric analysis of mineralized bone (SMD, 0.80; 95% CI, 0.42 to 1.19) when compared to traditional without-cell treatment in patients. However, evidence on gingival recession, alveolar thickness gain, bone mineral density of bone core, and bone volume fraction of bone core outcomes did not reach statistical significance.

Conclusions

Evidence suggests that the implementation of stem cell therapies in reconstructing compromised gingiva and alveolar bone tissue produces positive outcomes compared with conventional approaches. However, further well-designed investigations are needed to comprehensively identify the most effective source of cells and biomaterials for each case.

The current regenerative medicine approaches of craniofacial diseases: A narrative review

Craniofacial deformities (CFDs) develop following oncological resection, trauma, or congenital disorders. Trauma is one of the top five causes of death globally, with rates varying from country to country. They result in a non-healing composite tissue wound as they degenerate in soft or hard tissues. Approximately one-third of oral diseases are caused by gum disease. Due to the complexity of anatomical structures in the region and the variety of tissue-specific requirements, CFD treatments present many challenges. Many treatment methods for CFDs are available today, such as drugs, regenerative medicine (RM), surgery, and tissue engineering. Functional restoration of a tissue or an organ after trauma or other chronic diseases is the focus of this emerging field of science. The materials and methodologies used in craniofacial reconstruction have significantly improved in the last few years. A facial fracture requires bone preservation as much as possible, so tiny fragments are removed initially. It is possible to replace bone marrow stem cells with oral stem cells for CFDs due to their excellent potential for bone formation. This review article discusses regenerative approaches for different types of craniofacial diseases.

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.

Regenerative Potential of Granulation Tissue in Periodontitis: A Systematic Review and Meta-analysis

Methods

Electronic searches were conducted in five databases including CENTRAL, MEDLINE, EMBASE, Web of Science, and Dentistry & Oral Sciences Source using a combination of MeSH terms and keywords up to 21 June 2022. Human studies including patients aged over 18 years with all forms of periodontitis were included. Following the risk of bias assessment, both qualitative and quantitative analyses were performed.

Results

A total of twelve studies were included in qualitative analysis and six of them in quantitative analyses. The evidence suggested that cells derived from periodontitis granulation tissue have osteogenic, adipogenic, chondrogenic, neurogenic, and angiogenic differentiation abilities as well as immunoregulatory properties. In particular, CD44⁺, CD73⁺, CD90⁺, CD105⁺, and CD146⁺ cells were found widely in granulation tissue whilst the only meta-analysis confirmed that CD90⁺ cells were present in lower numbers within the granulation tissue when compared with healthy periodontal tissue (WMD = -23.43%, 95% CI -30.43 to -16.44, p < 0.00001).

Conclusions

This review provided further evidence that granulation tissue from patients with periodontitis can be a potential stem cell source for regenerative therapy.

Craniomaxillofacial derived bone marrow mesenchymal stem/stromal cells (BMSCs) for craniomaxillofacial bone tissue engineering: A literature review

Craniomaxillofacial bone defects seriously affect the appearance, function, and psychological status of patients. Traditional autologous bone grafting is very challenging due to the limited sources of bone tissue, excessive surgical trauma, and high incidence of related complications. Craniomaxillofacial bone tissue engineering (BTE) strategies based on bone marrow mesenchymal stem cells (BMSCs) are emerging as an alternative. Craniomaxillofacial BMSCs (C-BMSCs) are homologous to craniomaxillofacial bones, which develop from the mesoderm and neural crest. This article aims to compare the differences in osteogenesis, angiogenesis, and immune regulation of C-BMSCs and other sources of BMSCs, and propose ideas and strategies such as 3D printing and mechanotherapy to completely harness the characteristics of C-BMSCs. In conclusion, C-BSMCs are a promising source of stem cells for the repair and reconstruction of craniomaxillofacial bone defects, and more attention should be paid to accelerating their basic research and clinical practices.

Three-dimensional printing of clinical scale and personalized calcium phosphate scaffolds for alveolar bone reconstruction

OBJECTIVE

Alveolar bone defects can be highly variable in their morphology and, as the defect size increases, they become more challenging to treat with currently available therapeutics and biomaterials. This investigation sought to devise a protocol for fabricating customized clinical scale and patient-specific, bioceramic scaffolds for reconstruction of large alveolar bone defects.

METHODS

Two types of calcium phosphate (CaP)-based bioceramic scaffolds (alginate/β-TCP and hydroxyapatite/α-TCP, hereafter referred to as hybrid CaP and Osteoink™, respectively) were designed, 3D printed, and their biocompatibility with alveolar bone marrow stem cells and mechanical properties were determined. Following scaffold optimization, a workflow was developed to use cone beam computed tomographic (CBCT) imaging to design and 3D print, defect-specific bioceramic scaffolds for clinical-scale bone defects.

RESULTS

Osteoink™ scaffolds had the highest compressive strength when compared to hybrid CaP with different infill orientation. In cell culture medium, hybrid CaP degradation resulted in decreased pH (6.3) and toxicity to stem cells; however, OsteoInk™ scaffolds maintained a stable pH (7.2) in culture and passed the ISO standard for cytotoxicity. Finally, a clinically feasible laboratory workflow was developed and evaluated using CBCT imaging to engineer customized and defect-specific CaP scaffolds using OsteoInk™. It was determined that printed scaffolds had a high degree of accuracy to fit the respective clinical defects for which they were designed (0.27 mm morphological deviation of printed scaffolds from digital design).

SIGNIFICANCE

From patient to patient, large alveolar bone defects are difficult to treat due to high variability in their complex morphologies and architecture. Our findings shows that Osteoink™ is a biocompatible material for 3D printing of clinically acceptable, patient-specific scaffolds with precision-fit for use in alveolar bone reconstructive procedures. Collectively, emerging digital technologies including CBCT imaging, 3D surgical planning, and (bio)printing can be integrated to address this unmet clinical challenge.

Transforming the Degradation Rate of β-tricalcium Phosphate Bone Replacement Using 3-Dimensional Printing

BACKGROUND

β-Tricalcium phosphate (β-TCP) is one of the most common synthetic bone grafting materials utilized in craniofacial reconstruction; however, it is limited by a slow degradation rate. The aim of this study was to leverage 3-dimensional (3D) printing in an effort to accelerate the degradation kinetics of β-TCP.

METHODS

Twenty-two 1-month-old New Zealand white rabbits underwent creation of calvarial and alveolar defects, repaired with 3D-printed β-TCP scaffolds coated with 1000 μM of osteogenic agent dipyridamole. Rabbits were euthanized after 2, 6, and 18 months after surgical intervention. Bone regeneration, scaffold degradation, and bone mechanical properties were quantified.

RESULTS

Histological analysis confirmed the generation of vascularized and organized bone. Microcomputed tomography analysis from 2 to 18 months demonstrated decreased scaffold volume within calvarial (23.6% ± 2.5%, 5.1% ± 2.2%; P < 0.001) and alveolar (21.5% ± 2.2%, 0.2% ± 1.9%; P < 0.001) defects, with degradation rates of 54.6%/year and 90.5%/year, respectively. Scaffold-inducted bone generation within the defect was volumetrically similar to native bone in the calvarium (55.7% ± 6.9% vs 46.7% ± 6.8%; P = 0.064) and alveolus (31.4% ± 7.1% vs 33.8% ± 3.7%; P = 0.337). Mechanical properties between regenerated and native bone were similar.

CONCLUSIONS

Our study demonstrates an improved degradation profile and replacement of absorbed β-TCP with vascularized, organized bone through 3D printing and addition of an osteogenic agent. This novel additive manufacturing and tissue engineering protocol has implications to the future of craniofacial skeletal reconstruction as a safe and efficacious bone tissue engineering method.

Clinical Outcome and 8-Year Follow-Up of Alveolar Bone Tissue Engineering for Severely Atrophic Alveolar Bone Using Autologous Bone Marrow Stromal Cells with Platelet-Rich Plasma and β-Tricalcium Phosphate Granules

Background: Although bone tissue engineering for dentistry has been studied for many years, the clinical outcome for severe cases has not been established. Furthermore, there are limited numbers of studies that include long-term follow-up. In this study, the safety and efficacy of bone tissue engineering for patients with a severely atrophic alveolar bone were examined using autogenous bone marrow stromal cells (BMSCs), and the long-term stability was also evaluated. Methods: BMSCs from iliac bone marrow aspirate were cultured and expanded. Then, induced osteogenic cells were transplanted with autogenous platelet-rich plasma (PRP) and β-tricalcium phosphate granules (β-TCP) for maxillary sinus floor and alveolar ridge augmentation. Eight patients (two males and six females) with an average age of 54.2 years underwent cell transplantation. Safety was assessed by monitoring adverse events. Radiographic evaluation and bone biopsies were performed to evaluate the regenerated bone. Results: The major population of transplanted BMSCs belonged to the fraction of CD34⁻, CD45^dim, and CD73⁺ cells, which was only 0.065% of the total bone marrow cells. Significant deviations were observed in cell growth and alkaline phosphatase activities among individuals. However, bone regeneration was observed in all patients and the average bone area in the biopsy samples was 41.9% 6 months following transplantation, although there were also significant deviations among each case. No adverse events related to the transplants were observed. In the regenerated bone, 27 out of 29 dental implants were integrated. Dental implants and regenerated bone were stable for an average follow-up period of 7 years and 10 months. Conclusions: Although individual variations were observed, the results showed that bone tissue engineering using BMSCs with PRP and β-TCP was feasible for patients with severe atrophic maxilla throughout a long-term follow-up period and was considered safe. However, further studies with a larger number of cases and controls to confirm the efficacy of BMSCs and the development of a protocol to establish a reproducible quality of stem cell-based graft material will be required.

Clinical Applications of Cell-Scaffold Constructs for Bone Regeneration Therapy

Bone tissue engineering (BTE) is a process of combining live osteoblast progenitors with a biocompatible scaffold to produce a biological substitute that can integrate into host bone tissue and recover its function. Mesenchymal stem cells (MSCs) are the most researched post-natal stem cells because they have self-renewal properties and a multi-differentiation capacity that can give rise to various cell lineages, including osteoblasts. BTE technology utilizes a combination of MSCs and biodegradable scaffold material, which provides a suitable environment for functional bone recovery and has been developed as a therapeutic approach to bone regeneration. Although prior clinical trials of BTE approaches have shown promising results, the regeneration of large bone defects is still an unmet medical need in patients that have suffered a significant loss of bone function. In this present review, we discuss the osteogenic potential of MSCs in bone tissue engineering and propose the use of immature osteoblasts, which can differentiate into osteoblasts upon transplantation, as an alternative cell source for regeneration in large bone defects.

A systematic review on regenerative alveolar graft materials in clinical trials: Risk of bias and meta-analysis

BACKGROUND

Alveolar cleft grafting is a necessary procedure to restore bone defects. Randomized clinical trials (RCTs) are regarded as a golden standard for investigating the efficacy of treatments. Nevertheless, risk of bias (RoB) can still affect the validity of these trials. We aimed to conduct a systemic review of all control trials (CTs) using regenerative materials for alveolar cleft reconstructions to evaluate their RoB and perform a meta-analysis of new bone formation.

METHODS

Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (PubMed), EMBASE AND Google Scholar were searched up to October 2020. Thereafter, the articles underwent quality assessment (according to the Jadad scale and the Delphi list) for the evaluation of the RoB.

RESULTS

A total of 15 trials met the inclusion criteria, none of which reached a full score. Of these, 20% didn't randomize the trails, 73,33% failed to describe the way of randomization, and none reported the double-blinded criteria. Furthermore, allocation concealment (99.9%), intention to treat (100%), and patient awareness (100%) were inadequately described. The meta-analysis found no significant difference between regenerative materials and iliac crest graft.

CONCLUSION

This review showed high RoB in CTs implying quality improvement of CTs is necessary. Meta-analysis showed no significant difference between the regenerative materials and autogenous grafts.

Regenerative Medicine Technologies to Treat Dental, Oral, and Craniofacial Defects

Additive manufacturing (AM) is the automated production of three-dimensional (3D) structures through successive layer-by-layer deposition of materials directed by computer-aided-design (CAD) software. While current clinical procedures that aim to reconstruct hard and soft tissue defects resulting from periodontal disease, congenital or acquired pathology, and maxillofacial trauma often utilize mass-produced biomaterials created for a variety of surgical indications, AM represents a paradigm shift in manufacturing at the individual patient level. Computer-aided systems employ algorithms to design customized, image-based scaffolds with high external shape complexity and spatial patterning of internal architecture guided by topology optimization. 3D bioprinting and surface modification techniques further enhance scaffold functionalization and osteogenic potential through the incorporation of viable cells, bioactive molecules, biomimetic materials and vectors for transgene expression within the layered architecture. These computational design features enable fabrication of tissue engineering constructs with highly tailored mechanical, structural, and biochemical properties for bone. This review examines key properties of scaffold design, bioresorbable bone scaffolds produced by AM processes, and clinical applications of these regenerative technologies. AM is transforming the field of personalized dental medicine and has great potential to improve regenerative outcomes in patient care.

Achievements and Challenges in Transplantation of Mesenchymal Stem Cells in Otorhinolaryngology

Otorhinolaryngology enrolls head and neck surgery in various tissues such as ear, nose, and throat (ENT) that govern different activities such as hearing, breathing, smelling, production of vocal sounds, the balance, deglutition, facial animation, air filtration and humidification, and articulation during speech, while absence of these functions can lead to high morbidity and even mortality. Conventional therapies for head and neck damaged tissues include grafts, transplants, and artificial materials, but grafts have limited availability and cause morbidity in the donor site. To improve these limitations, regenerative medicine, as a novel and rapidly growing field, has opened a new therapeutic window in otorhinolaryngology by using cell transplantation to target the healing and replacement of injured tissues. There is a high risk of rejection and tumor formation for transplantation of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs); mesenchymal stem cells (MSCs) lack these drawbacks. They have easy expansion and antiapoptotic properties with a wide range of healing and aesthetic functions that make them a novel candidate in otorhinolaryngology for craniofacial defects and diseases and hold immense promise for bone tissue healing; even the tissue sources and types of MSCs, the method of cell introduction and their preparation quality can influence the final outcome in the injured tissue. In this review, we demonstrated the anti-inflammatory and immunomodulatory properties of MSCs, from different sources, to be safely used for cell-based therapies in otorhinolaryngology, while their achievements and challenges have been described too.

Clinical Efficacy of Mesenchymal Stem Cells in Bone Regeneration in Oral Implantology. Systematic Review and Meta-Analysis

In bone regeneration, obtaining a vital bone as similar as possible to native bone is sought. This review aimed to evaluate the efficacy of stem cells in maxillary bone regeneration for implant rehabilitation and to review the different techniques for obtaining and processing these cells. A systematic review and meta-analysis were performed using the Pubmed/Medline (NCBI), Cochrane, Scielo, and Scopus databases, without restriction on the publication date. The following Mesh terms were used, combined by the Boolean operator “AND”: “dental implants” AND “stem cells” AND “bioengineering”. Applying inclusion and exclusion criteria, five articles were obtained and three were added after manual search. The results from the meta-analysis (18 patients) did not provide significant differences despite the percentage of bone formed in the maxillary sinus, favoring the stem cell group, and the analysis of the percentage of residual Bio-Oss^® showed results favoring the control group. Stem cell regeneration usually shows positive vascular and viable bone formation. In conclusion, using mesenchymal stem cells in bone regeneration provides benefits in the quality of bone, similar or even superior to autologous bone, all this through a minimally invasive procedure.

Current and future trends in periodontal tissue engineering and bone regeneration

Periodontal tissue engineering involves a multi-disciplinary approach towards the regeneration of periodontal ligament, cementum and alveolar bone surrounding teeth, whereas bone regeneration specifically applies to ridge reconstruction in preparation for future implant placement, sinus floor augmentation and regeneration of peri-implant osseous defects. Successful periodontal regeneration is based on verifiable cementogenesis on the root surface, oblique insertion of periodontal ligament fibers and formation of new and vital supporting bone. Ultimately, regenerated periodontal and peri-implant support must be able to interface with surrounding host tissues in an integrated manner, withstand biomechanical forces resulting from mastication, and restore normal function and structure. Current regenerative approaches utilized in everyday clinical practice are mainly guided tissue/bone regeneration-based. Although these approaches have shown positive outcomes for small and medium-sized defects, predictability of clinical outcomes is heavily dependent on the defect morphology and clinical case selection. In many cases, it is still challenging to achieve predictable regenerative outcomes utilizing current approaches. Periodontal tissue engineering and bone regeneration (PTEBR) aims to improve the state of patient care by promoting reconstitution of damaged and lost tissues through the use of growth factors and signaling molecules, scaffolds, cells and gene therapy. The present narrative review discusses key advancements in PTEBR including current and future trends in preclinical and clinical research, as well as the potential for clinical translatability.

Clinical Application of Bone Marrow Mesenchymal Stem/Stromal Cells to Repair Skeletal Tissue

There has been an escalation in reports over the last decade examining the efficacy of bone marrow derived mesenchymal stem/stromal cells (BMSC) in bone tissue engineering and regenerative medicine-based applications. The multipotent differentiation potential, myelosupportive capacity, anti-inflammatory and immune-modulatory properties of BMSC underpins their versatile nature as therapeutic agents. This review addresses the current limitations and challenges of exogenous autologous and allogeneic BMSC based regenerative skeletal therapies in combination with bioactive molecules, cellular derivatives, genetic manipulation, biocompatible hydrogels, solid and composite scaffolds. The review highlights the current approaches and recent developments in utilizing endogenous BMSC activation or exogenous BMSC for the repair of long bone and vertebrae fractures due to osteoporosis or trauma. Current advances employing BMSC based therapies for bone regeneration of craniofacial defects is also discussed. Moreover, this review discusses the latest developments utilizing BMSC therapies in the preclinical and clinical settings, including the treatment of bone related diseases such as Osteogenesis Imperfecta.

Emerging local delivery strategies to enhance bone regeneration

In orthopedics and dentistry there is an increasing need for novel biomaterials and clinical strategies to achieve predictable bone regeneration. These novel molecular strategies have the potential to eliminate the limitations of currently available approaches. Specifically, they have the potential to reduce or eliminate the need to harvest autogenous bone, and the overall complexity of the clinical procedures. In this review, emerging tissue engineering strategies that have been, or are currently being, developed based on the current understanding of bone biology, development and wound healing will be discussed. In particular, protein/peptide based approaches, DNA/RNA therapeutics, cell therapy, and the use of exosomes will be briefly covered. The review ends with a summary of the current status of these approaches, their clinical translational potentials and their challenges.

Tissue engineering applications in otolaryngology-The state of translation

While tissue engineering holds significant potential to address current limitations in reconstructive surgery of the head and neck, few constructs have made their way into routine clinical use. In this review, we aim to appraise the state of head and neck tissue engineering over the past five years, with a specific focus on otologic, nasal, craniofacial bone, and laryngotracheal applications. A comprehensive scoping search of the PubMed database was performed and over 2000 article hits were returned with 290 articles included in the final review. These publications have addressed the hallmark characteristics of tissue engineering (cellular source, scaffold, and growth signaling) for head and neck anatomical sites. While there have been promising reports of effective tissue engineered interventions in small groups of human patients, the majority of research remains constrained to in vitro and in vivo studies aimed at furthering the understanding of the biological processes involved in tissue engineering. Further, differences in functional and cosmetic properties of the ear, nose, airway, and craniofacial bone affect the emphasis of investigation at each site. While otolaryngologists currently play a role in tissue engineering translational research, continued multidisciplinary efforts will likely be required to push the state of translation towards tissue-engineered constructs available for routine clinical use.

LEVEL OF EVIDENCE

NA.

Efficacy of autologous stem cells for bone regeneration during endosseous dental implants insertion - A systematic review of human studies

Availability of adequate quantity and quality of bone is prerequisite for longevity and survival of endosseous dental implants. Most of the clinicians face with the problem of lack of bone due to long-standing edentulism during this treatment modality. Conventional therapies with the use of various types of bone grafts and membranes have provided clinicians with unpredictable and compromised results. Cell-based therapies utilizing undifferentiated cells, that have the potential to differentiate into various cell types including osteoblastic lineages, have demonstrated through various previously conducted in-vitro and animal studies, a successful formation of bone in a predictable manner. Thus the main objective of this review was to evaluate the effectiveness of these therapies when applied on human subjects. A search was carried out in MEDLINE (via PubMed) and Cochrane CENTRAL databases for completed randomized and non-randomised clinical trials utilizing stem cell-based therapies with histologic and radiographic analysis written in English up to January 2019. This search of the literature yielded 10 studies meeting the inclusion and exclusion criteria. In all these studies, stem cells were primarily used to achieve bone augmentation during insertion of endosseous dental implants. Results of these therapies conducted on human subjects have shown a positive impact on bone regeneration, in particular, therapies utilizing bone marrow and adipose tissue derived stem cells. But the clinicians need to examine the efficacy, safety, feasibility of these therapies while treating large size defects or planning for shorter healing period and early loading of dental implants.

Tissue Engineering and Regenerative Medicine in Craniofacial Reconstruction and Facial Aesthetics

The craniofacial region is anatomically complex and is of critical functional and cosmetic importance, making reconstruction challenging. The limitations of current surgical options highlight the importance of developing new strategies to restore the form, function, and esthetics of missing or damaged soft tissue and skeletal tissue in the face and cranium. Regenerative medicine (RM) is an expanding field which combines the principles of tissue engineering (TE) and self-healing in the regeneration of cells, tissues, and organs, to restore their impaired function. RM offers many advantages over current treatments as tissue can be engineered for specific defects, using an unlimited supply of bioengineered resources, and does not require immunosuppression. In the craniofacial region, TE and RM are being increasingly used in preclinical and clinical studies to reconstruct bone, cartilage, soft tissue, nerves, and blood vessels. This review outlines the current progress that has been made toward the engineering of these tissues for craniofacial reconstruction and facial esthetics.

Bone Tissue Regeneration in the Oral and Maxillofacial Region: A Review on the Application of Stem Cells and New Strategies to Improve Vascularization

Bone tissue engineering techniques are a promising alternative for the use of autologous bone grafts to reconstruct bone defects in the oral and maxillofacial region. However, for successful bone regeneration, adequate vascularization is a prerequisite. This review presents and discusses the application of stem cells and new strategies to improve vascularization, which may lead to feasible clinical applications. Multiple sources of stem cells have been investigated for bone tissue engineering. The stromal vascular fraction (SVF) of human adipose tissue is considered a promising single source for a heterogeneous population of essential cells with, amongst others, osteogenic and angiogenic potential. Enhanced vascularization of tissue-engineered grafts can be achieved by different mechanisms: vascular ingrowth directed from the surrounding host tissue to the implanted graft, vice versa, or concomitantly. Vascular ingrowth into the implanted graft can be enhanced by (i) optimizing the material properties of scaffolds and (ii) their bioactivation by incorporation of growth factors or cell seeding. Vascular ingrowth directed from the implanted graft towards the host tissue can be achieved by incorporating the graft with either (i) preformed microvascular networks or (ii) microvascular fragments (MF). The latter may have stimulating actions on both vascular ingrowth and outgrowth, since they contain angiogenic stem cells like SVF, as well as vascularized matrix fragments. Both adipose tissue-derived SVF and MF are cell sources with clinical feasibility due to their large quantities that can be harvested and applied in a one-step surgical procedure. During the past years, important advancements of stem cell application and vascularization in bone tissue regeneration have been made. The development of engineered in vitro 3D models mimicking the bone defect environment would facilitate new strategies in bone tissue engineering. Successful clinical application requires innovative future investigations enhancing vascularization.

Cell-Based Therapies for Alveolar Bone and Periodontal Regeneration: Concise Review

Current regenerative strategies for alveolar bone and periodontal tissues are effective and well adopted. These are mainly based on the use of a combination of synthetic/natural scaffolds and bioactive agents, obviating the incorporation of cells. However, there are some inherent limitations associated with traditional techniques, and we hypothesized that the use of cell-based therapies as part of comprehensive regenerative protocols may help overcome these hurdles to enhance clinical outcomes. We conducted a systematic review of human controlled clinical trials investigating the clinical and/or histological effect of the use of cell-based therapies for alveolar bone and periodontal regeneration and explored the translational potential of the different cell-based strategies identified in the included trials. A total of 16 studies (11 randomized controlled trials, 5 controlled clinical trials) were included for data synthesis and qualitative analysis with meta-analyses performed when appropriate. The results suggest a clinical benefit from the use of cell therapy. Improved outcomes were shown for alveolar ridge preservation, lateral ridge augmentation, and periodontal regeneration. However, there was insufficient evidence to identify best-performing treatment modalities amongst the different cell-based techniques. In light of the clinical and histological outcomes, we identify extraction socket and challenging lateral and vertical bone defects requiring bone block grafts as strong candidates for the adjuvant application of mesenchymal stem cells. Given the complexity, invasiveness, and costs associated with techniques that include "substantial manipulation" of tissues and cells, their additional clinical benefit when compared with "minimal manipulation" must be elucidated in future trials. Stem Cells Translational Medicine 2019;8:1286&1295.

A new possibility in fertility preservation: The artificial ovary

Conventional fertility preservation methods such as oocyte or embryo cryopreservation are currently insufficient to treat including those patients with prepubertal cancer and premature ovarian failure. Ovarian tissue cryopreservation presents as an alternative but has limitations with a potential risk of reintroducing malignant cells in patients who recover from cancer, those of chemotherapy prior to tissue cryopreservation. The so called "artificial ovary" aims to resolve this issue by transplanting isolated follicles with or without a biological scaffold. The artificial ovary may also offer an effective alternative option for those who cannot benefit from traditional assisted reproductive techniques such as in vitro fertilisation. To date, in animal studies and human trial, the artificial ovary restored endocrine function, achieved in vivo follicular development, and resulted in successful pregnancies. However, development of a technique for higher follicular recovery rate and a more optimised design of delivery scaffold, better transplantation techniques to prevent postsurgical ischemia, and consideration for genetic safety are required for safer and consistent human clinical applications. Ideas from different transplantation surgeries (e.g., entire ovary, ovarian cortex, and transplantation with tissue-engineered products) can be applied to enhance the efficacy of artificial ovarian transplantation. For the better application of artificial ovary, a deeper understanding of mechanical and biochemical properties of the ovary and folliculogenesis after cryopreservation, transplantation with or without scaffold, and development of sophisticated in vivo imaging techniques of transplanted artificial ovary need to precede its efficient clinical application.

Small molecule inhibitor of TGF-β signaling enables robust osteogenesis of autologous GMSCs to successfully repair minipig severe maxillofacial bone defects

BACKGROUND

Clinically, for stem cell-based therapy (SCBT), autologous stem cells are considered better than allogenic stem cells because of little immune rejection and no risk of communicable disease infection. However, severe maxillofacial bone defects restoration needs sufficient autologous stem cells, and this remains a challenge worldwide. Human gingival mesenchymal stem cells (hGMSCs) derived from clinically discarded, easily obtainable, and self-healing autologous gingival tissues, have higher proliferation rate compared with autologous bone marrow mesenchymal stem cells (hBMSCs). But for clinical bone regeneration purpose, GMSCs have inferior osteogenic differentiation capability. In this study, a TGF-β signaling inhibitor SB431542 was used to enhance GMSCs osteogenesis in vitro and to repair minipig severe maxillofacial bone defects.

METHODS

hGMSCs were isolated and cultured from clinically discarded gingival tissues. The effects of SB431542 on proliferation, apoptosis, and osteogenic differentiation of hGMSCs were analyzed in vitro, and then, SB431542-treated hGMSCs composited with Bio-Oss® were transplanted into immunocompromised mice subcutaneously to explore osteogenic differentiation in vivo. After that, SB431542-treated autologous pig GMSCs (pGMSCs) composited with Bio-Oss® were transplanted into circular confined defects (5 mm × 12 mm) in minipigs maxillary to investigate severe bone defect regeneration. Minipigs were sacrificed at 2 months and nude mice at 8 weeks to retrieve specimens for histological or micro-CT or CBCT analysis. Effects of SB431542 on TGF-β and BMP signaling in hGMSCs were investigated by Western Blot or qRT-PCR.

RESULTS

One micromolar of SB431542 treatment induced a robust osteogenesis of hGMSCs in vitro, without adverse effect on apoptosis and growth. In vivo, 1 μM SB431542 treatment also enabled striking osteogenesis of hGMSCs subcutaneously in nude mice and advanced new bone formation of pGMSCs in minipig maxillary bone defect model. In addition, SB431542-treated hGMSCs markedly increased bone-related proteins expression, and BMP2 and BMP4 gene expression. Conversely, SMAD3 protein-dependent TGF-β signal pathway phosphorylation was decreased.

CONCLUSIONS

Our study show that osteogenic differentiation of GMSCs treated with TGF-β signaling inhibitor SB431542 was increased, and SB431542-treated autologous pig GMSCs could successfully repair minipig severe maxillofacial bone defects. This preclinical study brings about a promising large bone regeneration therapeutic potential of autologous GMSCs induced by SB431542 in clinic settings.

Expression of Musashi-1 During Osteogenic Differentiation of Oral MSC: An In Vitro Study

Background: Musashi-1 (MSI1) is a negative regulator of mesenchymal stromal cell (MSC) differentiation which in turn favors cell proliferation. However, little is known about its expression by MSC from the oral cavity and in the context of osteogenic differentiation. Aim: The aim of this study was to analyze the expression of MSI1 in the context of osteogenic differentiation of MSC derived from the oral cavity. Material/methods: For this in vitro study, MSC were isolated from six different origins of the oral cavity. They were extensively characterized in terms of proliferative and clonogenicity potential, expression of stemness genes (MYC, NANOG, POU5F1, and SOX2), expression of surface markers (CD73, CD90, CD105, CD14, CD31, CD34, and CD45) and adipo-, chondro- and osteogenic differentiation potential. Then, osteogenic differentiation was induced and the expression of MSI1 mRNA and other relevant markers of osteogenic differentiation, including RUNX2 and Periostin, were also evaluated. Results: Cell populations from the alveolar bone (pristine or previously grafted with xenograft), dental follicle, dental germ, dental pulp, and periodontal ligament were obtained. The analysis of proliferative and clonogenicity potential, expression of the stemness genes, expression of surface markers, and differentiation potential showed similar characteristics to those of previously published MSC from the umbilical cord. Under osteogenic differentiation conditions, all MSC populations formed calcium deposits and expressed higher SPARC. Over time, the expression of MSI1 followed different patterns for the different MSC populations. It was not significantly different than the expression of RUNX2. In contrast, the expression of MSI1 and POSTN and RUNX2 were statistically different in most MSC populations. Conclusion: In the current study, a similar expression pattern of MSI1 and RUNX2 during in vitro osteogenic differentiation was identified.

Improved bone regeneration through amniotic membrane loaded with buccal fat pad-derived MSCs as an adjuvant in maxillomandibular reconstruction

BACKGROUND

Human amniotic membranes (HAMs), as a biological membrane with healing, osteogenic, and cell therapy potential, has been in the spotlight to enhance the outcomes of treating bone defects. Present study aims to clinically assess the potential of HAM loaded with buccal fat pad-derived stem cells (BFSCs) as an osteogenic coverage for onlay bone grafts to maxillomandibular bone defects.

MATERIALS AND METHODS

Nine patients with jaw bone defects were enrolled in the present study. The patients were allocated to two study groups: Iliac crest bone graft with HAM coverage (n = 5), and Iliac bone grafts covered with HAM loaded with BFSCs (n = 4). Five months following the grafting and prior to implant placement, cone beam computed tomography was performed for radiomorphometric analysis.

RESULTS

The mean increase in bone width was found to be significantly greater in the HAM + BFSCs group (4.42 ± 1.03 mm versus 3.07 ± 0.73 mm, p < 0.05). Further, the changes in vertical dimension were greater in the HAM + BFSCs group (4.66 ± 1.06 mm versus 4.14 ± 1.03 mm, p > 0.05).

CONCLUSION

Combined use of HAM with mesenchymal stem cells may enhance bone regeneration specifically in the horizontal dimension. Moreover, this methodology reduces the amount of harvested autogenous bone and diminish secondary bone resorption.

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

The aim of this review was to test the hypothesis of no difference in the efficacy of bone regeneration when using stem cells in maxillary sinus floor augmentation surgery in comparison to other grafts. Nine randomized clinical trials and one follow-up study involving human subjects were identified through a search of the PubMed/MEDLINE, Scopus, Cochrane, and Web of Science databases, supplemented by a hand search. No significant difference between groups was found for the implant survival rate, increase in bone height, marginal bone loss following implant placement, or new bone formation. With regard to the residual bone graft, an effect favouring the graft group at 3-4months (P=0.001) and favouring the stem cell group at 6months (P=0.01) was found. Analyses of the subgroup in which the BMAC system extraction method was used in combination with Bio-Oss, revealed no difference in new bone formation; however, the results for residual bone graft at 3months favoured the control graft (Bio-Oss) (P=0.01), but at 6months favoured the stem cells (Bio-Oss+BMAC system) (P=0.01). Based on all findings, the use of stem cells does not contribute significantly to greater implant survival rates or the efficacy of bone regeneration following sinus lift procedures.

Sinus floor elevation using particulate PLGA-coated biphasic calcium phosphate bone graft substitutes: A prospective histological and radiological study

BACKGROUND

Poly (lactic-co-glycolic acid) (PLGA) is widely used for the development of delivery systems for drugs and therapeutic biomolecules in tissue engineering applications. Particles of biphasic calcium phosphate can be covered by PLGA to change their manipulating characteristics.

PURPOSE

Aim of this study was to investigate the radiological and histomorphometric results of the use of PLGA-coated biphasic calcium phosphate granules in sinus floor elevation and to analyze the underlying molecular processes by immunohistochemical staining.

MATERIALS AND METHODS

A randomized clinical study was designed to include patients in need of sinus floor elevation. Patients were assigned to receive either PLGA-coated biphasic calcium phosphate particles (group I) or the equivalent but noncoated particles (group II). Cone beam computed tomography (CBCT) scans were performed before and 6 months after the procedure to assess the bone height gain. At the time of implant placement, bone core biopsies were obtained at the site of implant placement. Histological sections were subjected to histomorphometric and immunohistochemical evaluation of differentiation markers (Musashi-1 [MSI1]).

RESULTS

No statistically significant differences were observed between groups for the radiologic parameters. No differences were observed histologically or histomorphometrically. However, PLGA-coated particles (group I) were more colonized by MSI1-positive osteoblast precursors (P = 0.0001, chi-squared test) and were penetrated by more CD34-positive vascular structures (P = 0.001, chi-squared test) than noncoated particles (group II).

CONCLUSIONS

PLGA-coated particles are associated with more MSI11-positive cells and more extensive microvascularization than noncoated particles.

Bone, Periodontal and Dental Pulp Regeneration in Dentistry: A Systematic Scoping Review

The aim of presented systematic scoping review was to investigate the actual and future clinical possibilities of regenerative therapies and their ability to regenerate bone, periodontal and pulp with histological confirmation of the nature of formed tissue. Electronic search was conducted using a combination between Keywords and MeSH terms in PubMed, Scopus, ISI-Web of Science and Cochrane library databases up to January 2016. Two reviewers conducted independently the papers judgment. Screened studies were read following the predetermined inclusion criteria. The included studies were evaluated in accordance with Arksey and O'Malley's modified framework. From 1349 papers, 168 completed inclusion criteria. Several characterized and uncharacterized cells used in Cell Therapy have provided bone regeneration, demonstrating bone gain in quantity and quality, even as accelerators for bone and periodontal regeneration. Synthetic and natural scaffolds presented good cell maintenance, however polyglycolid-polylactid presented faster resorption and consequently poor bone gain. The Growth Factor-Mediated Therapy was able to regenerate bone and all features of a periodontal tissue in bone defects. Teeth submitted to Revascularization presented an increase of length and width of root canal. However, formed tissues not seem able to deposit dentin, characterizing a repaired tissue. Both PRP and PRF presented benefits when applied in regenerative therapies as natural scaffolds. Therefore, most studies that applied regenerative therapies have provided promising results being possible to regenerate bone and periodontal tissue with histological confirmation. However, pulp regeneration was not reported. These results should be interpreted with caution due to the short follow-up periods.

Composite Alloplastic Biomaterial vs. Autologous Platelet-Rich Fibrin in Ridge Preservation

AIM

The aim of this study was to examine the clinical and histological differences of using a combination of alloplastic beta triphasic calcium phosphate (β-TCP) and a cross-linked collagen membrane versus autologous platelet-rich fibrin (PRF-L) in ridge preservation after dental extraction.

MATERIAL AND METHODS

Fifty-one patients were included in this observational case-series study. Dental extractions were performed, after which 25 patients were grafted with β-TCP and 26 with PRF-L. After four months of healing, clinical, radiological, histomorphometric and histological evaluations were performed.

RESULTS

A significantly higher percentage of mineralized tissue was observed in samples from the PRF-L grafted areas. Cellularity was higher in PRF-L grafted areas (osteocytes in newly formed bone per mm² = 123.25 (5.12) vs. 84.02 (26.53) for PRF-L and β-TCP, respectively, p = 0.01). However, sockets grafted with PRF-L showed a higher reduction in the bucco-lingual dimension after four months of healing (2.19 (0.80) vs. 1.16 (0.55) mm, p < 0.001), as well as a higher alteration in the final position of the mid muco-gingival junction (1.73 (1.34) vs. 0.88 (0.88) mm, p < 0.01).

CONCLUSION

PRF-L concentrate accelerates wound healing in post-extraction sockets in terms of new mineralized tissue component. However, the use of β-TCP biomaterial appears to be superior to maintain bucco-lingual volume and the final position of the muco-gingival junction.

The role of sclerostin and dickkopf-1 in oral tissues - A review from the perspective of the dental disciplines

Wnt signaling is of high relevance in the development, homeostasis, and regeneration of oral tissues. Therefore, Wnt signaling is considered to be a potential target for therapeutic strategies. The action of Wnt is tightly controlled by the inhibitors sclerostin (SOST) and Dickkopf (DKK)-1. Given the impact of SOST and DKK-1 in hard tissue formation, related diseases and healing, it is of high relevance to understand their role in oral tissues. The clinical relevance of this knowledge is further underlined by systemic and local approaches which are currently in development for treating a variety of diseases such as osteoporosis and inflammatory hard tissue resorption. In this narrative review, we summarize the current knowledge and understanding on the Wnt signaling inhibitors SOST and DKK-1, and their role in physiology, pathology, and regeneration in oral tissues. We present this role from the perspective of the different specialties in dentistry, including endodontics, orthodontics, periodontics, and oral surgery.

Evaluation of the Osteogenic Potential of Different Scaffolds Embedded with Human Stem Cells Originated from Schneiderian Membrane: An In Vitro Study

BACKGROUND

Novel treatments for bone defects, particularly in patients with poor regenerative capacity, are based on bone tissue engineering strategies which include mesenchymal stem cells (MSCs), bioactive factors, and convenient scaffold supports.

OBJECTIVE

In this study, we aimed at comparing the potential for different scaffolds to induce osteogenic differentiation of human maxillary Schneiderian sinus membrane- (hMSSM-) derived cells. Methods. hMSSM-derived cells were seeded on gelatin, collagen, or Hydroxyapatite β-Tricalcium phosphate-Fibrin (Haβ-TCP-Fibrin) scaffolds. Cell viability was determined using an MTT assay. Alizarin red staining method, Alkaline phosphatase (ALP) activity assay, and quantitative real-time PCR analysis were performed to assess hMSSM-derived cells osteogenic differentiation.

RESULTS

Cell viability, calcium deposition, ALP activity, and osteoblastic markers transcription levels were most striking in gelatin scaffold-embedded hMSSM-derived cells.

CONCLUSION

Our findings suggest a promising potential for gelatin-hMSSM-derived cell construct for treating bone defects.

Modern Trends in Dental Medicine: An Update for Internists

Traumatic injuries, genetic diseases, and external harmful agents such as bacteria and acids often compromise tooth integrity. There is an unmet medical need to develop alternative, innovative dental treatments that complement traditional restorative and surgery techniques. Stem cells have transformed the medical field in recent years. The combination of stem cells with bioactive scaffolds and nanostructured materials turns out to be increasingly beneficial in regenerative dental medicine. Stem cell-based regenerative approaches for the formation of dental tissues will significantly improve treatments and will have a major impact in dental practice. To date there is no established and reliable stem cell-based treatment translated into the dental clinics, however, the advances and improved technological knowledge are promising for successful dental therapies in the near future. Here, we review some of the contemporary challenges in dental medicine and describe the benefits and future possibilities of certain novel approaches in the emerging field of regenerative dentistry.

Continuing Challenges in Advancing Preclinical Science in Skeletal Cell-Based Therapies and Tissue Regeneration

Cell-based therapies hold much promise for musculoskeletal medicine; however, this rapidly growing field faces a number of challenges. Few of these therapies have proven clinical benefit, and an insufficient regulatory environment has allowed for widespread clinical implementation without sufficient evidence of efficacy. The technical and biological complexity of cell-based therapies has contributed to difficulties with reproducibility and mechanistic clarity. In order to aid in addressing these challenges, we aim to clarify the key issues in the preclinical cell therapy field, and to provide a conceptual framework for advancing the state of the science. Broadly, these suggestions relate to: (i) delineating cell-therapy types and moving away from "catch-all" terms such as "stem cell" therapies; (ii) clarifying descriptions of cells and their processing; and (iii) increasing the standard of in vivo evaluation of cell-based therapy experiments to determining cell fates. Further, we provide an overview of methods for experimental evaluation, data sharing, and professional society participation that would be instrumental in advancing this field. © 2018 American Society for Bone and Mineral Research.

Preconditioning of bone marrow-derived mesenchymal stem cells with N-acetyl-L-cysteine enhances bone regeneration via reinforced resistance to oxidative stress

Oxidative stress on transplanted bone marrow-derived mesenchymal stem cells (BMSCs) during acute inflammation is a critical issue in cell therapies. N-acetyl-L cysteine (NAC) promotes the production of a cellular antioxidant molecule, glutathione (GSH). The aim of this study was to investigate the effects of pre-treatment with NAC on the apoptosis resistance and bone regeneration capability of BMSCs. Rat femur-derived BMSCs were treated in growth medium with or without 5 mM NAC for 6 h, followed by exposure to 100 μM H₂O₂ for 24 h to induce oxidative stress. Pre-treatment with NAC significantly increased intracellular GSH levels by up to two fold and prevented H₂O₂-induced intracellular redox imbalance, apoptosis and senescence. When critical-sized rat femur defects were filled with a collagen sponge containing fluorescent-labeled autologous BMSCs with or without NAC treatment, the number of apoptotic and surviving cells in the transplanted site after 3 days was significantly lower and higher in the NAC pre-treated group, respectively. By the 5th week, significantly enhanced new bone formation was observed in the NAC pre-treated group. These data suggest that pre-treatment of BMSCs with NAC before local transplantation enhances bone regeneration via reinforced resistance to oxidative stress-induced apoptosis at the transplanted site.