Injectable bone tissue engineering using expanded mesenchymal stem cells

Prevention of bone dehiscence associated with orthodontic tooth movement by prophylactic injection of bone anabolic agents in mice

Although bone dehiscence may occur during orthodontic tooth movement into the narrow alveolar ridge, a non-invasive prevention method is yet to be fully established. We show for the first time prevention of bone dehiscence associated with orthodontic tooth movement by prophylactic injection of bone anabolic agents in mice. In this study, we established a bone dehiscence mouse model by applying force application and used the granular type of scaffold materials encapsulated with bone morphogenetic protein (BMP)-2 and OP3-4, the receptor activator of NF-κB ligand (RANKL)-binding peptide, for the prophylactic injection to the alveolar bone. In vivo micro-computed tomography revealed bone dehiscence with decreased buccal alveolar bone thickness and height after force application, whereas no bone dehiscence was observed with the prophylactic injection after force application, and alveolar bone thickness and height were kept at similar levels as those in the control group. Bone histomorphometry analyses revealed that both bone formation and resorption parameters were significantly higher in the injection with force application group than in the force application without the prophylactic injection group. These findings suggest that the prophylactic local delivery of bone anabolic reagents can prevent bone dehiscence with increased bone remodelling activity.

Evaluation of Osteogenic Potential for Rat Adipose-Derived Stem Cells under Xeno-Free Environment

This study aimed to develop a novel culture method for rat adipose-derived stem cells (rADSC) and evaluate their osteogenic potential. The rADSC cultured in xeno-free culture medium (XF-rADSCs) or conventional culture medium containing fetal bovine serum (FBS-rADSCs) were combined with micropieces of xeno-free recombinant collagen peptide to form 3-dimensional aggregates (XF-rADSC-CellSaic or FBS-rADSC-CellSaic). Both FBS-rADSC and XF-ADSC in CellSaic exhibited multilineage differentiation potential. Compared to FBS-rADSC-CellSaic, XF-rADSC-CellSaic accelerated and promoted osteogenic differentiation in vitro. When transplanted into rat mandibular congenital bone defects, the osteogenically differentiated XF-rADSC-CellSaic induced regeneration of bone tissue with a highly maturated structure compared to FBS-rADSC-CellSaic. In conclusion, XF-rADSC-CellSaic is a feasible 3-dimensional platform for efficient bone formation.

The Role and Involvement of Stem Cells in Periodontology

Periodontitis is a widespread inflammatory condition, characterized by a progressive deterioration of the supporting structures of the teeth. Due to the complexity of periodontal tissue and the surrounding inflammatory microenvironment, the repair of lesions at this level represents a continuous challenge. The regeneration of periodontal tissues is considered a promising strategy. Stem cells have remarkable properties, such as immunomodulatory potential, proliferation, migration, and multilineage differentiation. Thus, they can be used to repair tissue damage and reduce inflammation, potentially leading to periodontal regeneration. Among the stem cells used for periodontal regeneration, we studied dental mesenchymal stem cells (DMSCs), non-dental stem cells, and induced pluripotent stem cells (IPSCs). Although these cells have well documented important physiological characteristics, their use in contemporary practice to repair the affected periodontium is still a challenge.

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.

Stem Cell Applications in Periodontal Regeneration

In this review, the authors consider the substantial advances that have been made in recent years in stem cell-based periodontal regeneration. These advances involve identifying dental- and nondental-derived stem cells with the capacity to modulate periodontal regeneration, human clinical trials, and emerging concepts, including cell banking, good manufacturing processes, and overall clinical translation.

Periodontal regeneration using a xenogeneic bone substitute seeded with autologous periodontal ligament-derived mesenchymal stem cells: A 12-month quasi-randomized controlled pilot clinical trial

AIM

To evaluate the safety and efficacy of autologous periodontal ligament-derived mesenchymal stem cells (PDL-MSCs) embedded in a xenogeneic bone substitute (XBS) for the regenerative treatment of intra-bony periodontal defects.

MATERIAL AND METHODS

This quasi-randomized controlled pilot phase II clinical trial included patients requiring a tooth extraction and presence of one intra-bony lesion (1-2 walls). Patients were allocated to either the experimental (XBS + 10 × 10⁶ PDL-MSCs/100 mg) or the control group (XBS). Clinical and radiographical parameters were recorded at baseline, 6, 9 and 12 months. The presence of adverse events was also evaluated. Chi-square, Student's t test, Mann-Whitney U, repeated-measures ANOVA and regression models were used.

RESULTS

Twenty patients were included. No serious adverse events were reported. Patients in the experimental group (n = 9) showed greater clinical attachment level (CAL) gain (1.44, standard deviation [SD] = 1.87) and probing pocket depth (PPD) reduction (2.33, SD = 1.32) than the control group (n = 10; CAL gain = 0.88, SD = 1.68, and PPD reduction = 2.10, SD = 2.46), without statistically significant differences.

CONCLUSION

The application of PDL-MSCs to XBS for the treatment of one- to two-wall intra-bony lesions was safe and resulted in low postoperative morbidity and appropriate healing, although its additional benefit, when compared with the XBS alone, was not demonstrated.

The platelet-rich plasma and mesenchymal stem cell milieu: A review of therapeutic effects on bone healing

Platelet-rich plasma is autologous plasma that contains concentrated platelets compared to whole blood. It is relatively inexpensive to produce, can be easily isolated from whole blood, and can be administered while the patient is in the operating room. Further, because platelet-rich plasma is an autologous therapy, there is minimal risk for adverse reactions to the patient. Platelet-rich plasma has been used to promote bone regeneration due to its abundance of concentrated growth factors that are essential to wound healing. In this review, we summarize the methods for producing platelet-rich plasma and the history of its use in bone regeneration. We also summarize the growth factor profiles derived from platelet-rich plasma, with emphasis on those factors that play a direct role in promoting bone repair within the local fracture environment. In addition, we discuss the potential advantages of combining platelet-rich plasma with mesenchymal stem cells, a multipotent cell type often obtained from bone marrow or fat, to improve craniofacial and long bone regeneration. We detail what is currently known about how platelet-rich plasma influences mesenchymal stem cells in vitro, and then highlight the clinical outcomes of administering platelet-rich plasma and mesenchymal stem cells as a combination therapy to promote bone regeneration in vivo.

Mass acquisition of human periodontal ligament stem cells

The periodontal ligament (PDL) is an essential fibrous tissue for tooth retention in the alveolar bone socket. PDL tissue further functions to cushion occlusal force, maintain alveolar bone height, allow orthodontic tooth movement, and connect tooth roots with bone. Severe periodontitis, deep caries, and trauma cause irreversible damage to this tissue, eventually leading to tooth loss through the destruction of tooth retention. Many patients suffer from these diseases worldwide, and its prevalence increases with age. To address this issue, regenerative medicine for damaged PDL tissue as well as the surrounding tissues has been extensively investigated regarding the potential and effectiveness of stem cells, scaffolds, and cytokines as well as their combined applications. In particular, PDL stem cells (PDLSCs) have been well studied. In this review, I discuss comprehensive studies on PDLSCs performed in vivo and contemporary reports focusing on the acquisition of large numbers of PDLSCs for therapeutic applications because of the very small number of PDLSCs available in vivo.

Immunomodulatory Properties of Stem Cells in Periodontitis: Current Status and Future Prospective

Periodontitis is the sixth-most prevalent chronic inflammatory disease and gradually devastates tooth-supporting tissue. The complexity of periodontal tissue and the local inflammatory microenvironment poses great challenges to tissue repair. Recently, stem cells have been considered a promising strategy to treat tissue damage and inflammation because of their remarkable properties, including stemness, proliferation, migration, multilineage differentiation, and immunomodulation. Several varieties of stem cells can potentially be applied to periodontal regeneration, including dental mesenchymal stem cells (DMSCs), nonodontogenic stem cells, and induced pluripotent stem cells (iPSCs). In particular, these stem cells possess extensive immunoregulatory capacities. In periodontitis, these cells can exert anti-inflammatory effects and regenerate the periodontium. Stem cells derived from infected tissue possess typical stem cell characteristics with lower immunogenicity and immunosuppression. Several studies have demonstrated that these cells can also regenerate the periodontium. Furthermore, the interaction of stem cells with the surrounding infected microenvironment is critical to periodontal tissue repair. Though the immunomodulatory capabilities of stem cells are not entirely clarified, they show promise for therapeutic application in periodontitis. Here, we summarize the potential of stem cells for periodontium regeneration in periodontitis and focus on their characteristics and immunomodulatory properties as well as challenges and perspectives.

Evaluation of a cell-based osteogenic formulation compliant with good manufacturing practice for use in tissue engineering

Proper bony tissue regeneration requires mechanical stabilization, an osteogenic biological activity and appropriate scaffolds. The latter two elements can be combined in a hydrogel format for effective delivery, so it can readily adapt to the architecture of the defect. We evaluated a Good Manufacturing Practice-compliant formulation composed of bone marrow-derived mesenchymal stromal cells in combination with bone particles (Ø = 0.25 to 1 µm) and fibrin, which can be readily translated into the clinical setting for the treatment of bone defects, as an alternative to bone tissue autografts. Remarkably, cells survived with unaltered phenotype (CD73⁺, CD90⁺, CD105⁺, CD31^-, CD45^-) and retained their osteogenic capacity up to 48 h after being combined with hydrogel and bone particles, thus demonstrating the stability of their identity and potency. Moreover, in a subchronic toxicity in vivo study, no toxicity was observed upon subcutaneous administration in athymic mice and signs of osteogenesis and vascularization were detected 2 months after administration. The preclinical data gathered in the present work, in compliance with current quality and regulatory requirements, demonstrated the feasibility of formulating an osteogenic cell-based tissue engineering product with a defined profile including identity, purity and potency (in vitro and in vivo), and the stability of these attributes, which complements the preclinical package required prior to move towards its use of prior to its clinical use.

Promising advances in clinical trials of dental tissue-derived cell-based regenerative medicine

Background

Advances in regenerative medicine with stem cells have led to clinical trials. Dental/oral tissues are emerging as promising cellular sources of human mesenchymal stem cells. Recently, dental tissue-derived cells have been used clinically due to their great potential, easy accessibility, and ability to be obtained via methods with low invasiveness. The aim of this study is to systematically assess the clinical effectiveness of dental cell-mediated therapies compared to current evidence-based methods in human patients.

Methods

The electronic databases MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov were searched up to December 2019 for clinical trials. Clinical trials with any intervention using stem cells/cells derived from dental tissue were included.

Results

A total of 815 studies were identified by the electronic search, and 38 articles qualified for full-text evaluation. Finally, 20 studies (10 clinical trials using dental pulp-derived cells, 3 clinical trials using periodontal ligament-derived cells, and 7 studies using gingiva-derived cells) were included in this review. No clinical trials using dental follicle- or apical papilla-derived cells were selected in this review. Dental pulp-derived cells were used in clinical trials for bone regeneration, periodontitis, and dental pulp regeneration. All clinical trials using periodontal ligament-derived cells and gingiva-derived cells were conducted for periodontal disease treatment and gingival augmentation, respectively. Among the 20 selected studies, 16 showed clinical benefits of cell transplantation therapies. In addition, no study reported adverse events that may have been associated with cell transplantation.

Conclusions

These findings indicate that dental tissue-derived cells would be useful for cell-based regenerative medicine for various diseases.

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.

Diagnostic Cytokines and Comparative Analysis Secreted from Exfoliated Deciduous Teeth, Dental Pulp, and Bone Marrow Derived Mesenchymal Stem Cells for Functional Cell-Based Therapy

The aim of the study was to clarify the distinctive features of stem cells for effective cell-based therapy strategies in regenerative medicine. The expression levels of cytokines secreted from stem cells from exfoliated deciduous teeth (SHED), dental pulp stem cells (DPSCs), and bone marrow derived mesenchymal stem cells (BMMSCs) were examined to identify the details of their characteristics. A total of 174 cytokines were analyzed using cytokine antibody array, and their expression levels were confirmed by an enzyme-linked immunosorbent assay. These results indicated that 11 cytokines that were related to tissue regeneration, including growth factors, chemokines, and inflammatory cytokines, were identical in SHED, DPSCs, and BMMSCs. The comparative analyses between SHED and BMMSCs revealed that hepatocyte growth factor (HGF), matrix metalloproteinase-3, and stromal cell derived factor 1 (SDF-1) were expressed 6.7-, 2.5-, and 2.1-fold higher, respectively, in SHEDs. HGF was also expressed 3.4-fold higher in DPSCs than BMMSCs. Monocyte chemoattractant protein-1, and-3 were expressed more strongly in BMMSCs. SHED contained significantly higher SDF-1 levels than DPSCs. The distinct cytokine secretion indicated that they had different character besides basic MSC features. This knowledge of diagnostic cytokines analysis secreted from SHED, DPSCs, and BMMSCs extends our understanding, and can provide a novel therapeutic paradigm shift for functional cell-based therapy.

Clinical application of mesenchymal stem cells in periodontal regeneration: A systematic review and meta-analysis

OBJECTIVE

To evaluate the potential efficacy of mesenchymal stem cells (MSCs) in periodontal regeneration in humans on the following main outcomes: clinical attachment level (CAL), probing depth (PD), and gingival recession (GR).

BACKGROUND

The clinical application of stem cells in periodontal regeneration has begun in recent years, but clinical practices are not yet standardized and no recommendations are available at this time.

METHODS

Electronic database searches and hand searches were conducted. All types of studies, case series, and case reports were qualitatively described. Double-blind randomized controlled trials (RCTs) evaluating MSCs in periodontal regeneration were included in a meta-analysis if they compared administration of MSCs vs application of stem cell-free therapy in the control group, in healthy patients with periodontal defects, with a minimum of three mo of follow-up.

RESULTS

Fifteen reports were included in qualitative analysis, involving 123 patients and 158 periodontal defects. Only two small RCTs at high risk of bias, with a total of 59 patients and 70 periodontal defects, were included in the meta-analysis. A small but significant difference between test and control groups was found for CAL at three mo (-0.90 mm, 95% CI [-1.51; -0.29]), but not for PD and GR.

CONCLUSION

Low-quality evidence suggests that MSC-based therapy may have a small impact on periodontal regeneration. However, due to the monocentric character, the small sample size, and potential heterogeneity across the two included RCTs, these results must not be considered as definitive. High-quality RCTs are needed before any clinical use of MSCs in periodontal regeneration.

Bone Marrow-Derived CD44+ Cells Migrate to Tissue-Engineered Constructs via SDF-1/CXCR4-JNK Pathway and Aid Bone Repair

Background and Aims

Host-derived cells play crucial roles in the regeneration process of tissue-engineered constructs (TECs) during the treatment of large segmental bone defects (LSBDs). However, their identity, source, and cell recruitment mechanisms remain elusive.

Methods

A complex model was created using mice by combining methods of GFP⁺ bone marrow transplantation (GFP-BMT), parabiosis (GFP⁺-BMT and wild-type mice), and femoral LSBD, followed by implantation of TECs or DBM scaffolds. Postoperatively, the migration of host BM cells was detected by animal imaging and immunofluorescent staining. Bone repair was evaluated by micro-CT. Signaling pathway repressors including AMD3100 and SP600125 associated with the migration of BM CD44⁺ cells were further investigated. In vitro, transwell migration and western-blotting assays were performed to verify the related signaling pathway. In vivo, the importance of the SDF-1/CXCR4-JNK pathway was validated by ELISA, fluorescence-activated cell sorting (FACS), immunofluorescent staining, and RT-PCR.

Results

First, we found that host cells recruited to facilitate TEC-mediated bone repair were derived from bone marrow and most of them express CD44, indicating the significance of CD44 in the migration of bone marrow cells towards donor MSCs. Then, the predominant roles of SDF-1/CXCR4 and downstream JNK in the migration of BM CD44⁺ cells towards TECs were demonstrated.

Conclusion

Together, we demonstrated that during bone repair promoted by TECs, BM-derived CD44⁺ cells were essential and their migration towards TECs could be regulated by the SDF-1/CXCR4-JNK signaling pathway.

Application of Periodontal Ligament-Derived Multipotent Mesenchymal Stromal Cell Sheets for Periodontal Regeneration

Periodontitis is a chronic inflammatory disorder that causes destruction of the periodontal attachment apparatus including alveolar bone, the periodontal ligament, and cementum. Dental implants have been routinely installed after extraction of periodontitis-affected teeth; however, recent studies have indicated that many dental implants are affected by peri-implantitis, which progresses rapidly because of the failure of the immune system. Therefore, there is a renewed focus on periodontal regeneration aroundnatural teeth. To regenerate periodontal tissue, many researchers and clinicians have attempted to perform periodontal regenerative therapy using materials such as bioresorbable scaffolds, growth factors, and cells. The concept of guided tissue regeneration, by which endogenous periodontal ligament- and alveolar bone-derived cells are preferentially proliferated by barrier membranes, has proved effective, and various kinds of membranes are now commercially available. Clinical studies have shown the significance of barrier membranes for periodontal regeneration; however, the technique is indicated only for relatively small infrabony defects. Cytokine therapies have also been introduced to promote periodontal regeneration, but the indications are also for small size defects. To overcome this limitation, ex vivo expanded multipotent mesenchymal stromal cells (MSCs) have been studied. In particular, periodontal ligament-derived multipotent mesenchymal stromal cells are thought to be a responsible cell source, based on both translational and clinical studies. In this review, responsible cell sources for periodontal regeneration and their clinical applications are summarized. In addition, recent transplantation strategies and perspectives about the cytotherapeutic use of stem cells for periodontal regeneration are discussed.

Screen-enrich-combine circulating system to prepare MSC/β-TCP for bone repair in fractures with depressed tibial plateau

Aim: To evaluate the clinical efficacy of mesenchymal stem cell/β-tricalcium phosphate composites (MSC/β-TCP) prepared with a screen-enrich-combine circulating system (SECCS) in patients with depressed tibial plateau fractures. Materials & methods: Bone defects in depressed tibial plateaus were filled with MSC/β-TCP (n = 16) or with β-TCP only (n = 23). Enrichment efficiency and effect of enrichment on cell viability were evaluated. Clinical results were assessed by imaging examination and Lysholm score. Results: SECCS effectively integrated MSCs with β-TCP. At 18 months postimplantation, new bone ratio was significantly higher in patients treated with MSC/β-TCP than in those treated with β-TCP only (p = 0.000). Patients with MSC/β-TCP implants had better functional recovery (p = 0.028). Conclusion: MSC/β-TCP prepared by SECCS were effective in the treatment of bone defects in patients with depressed tibial plateau fractures, promoted bone regeneration and improved joint function recovery.

Regenerative Capacity of Adipose Derived Stem Cells (ADSCs), Comparison with Mesenchymal Stem Cells (MSCs)

Adipose tissue is now on the top one of stem cell sources regarding its accessibility, abundance, and less painful collection procedure when compared to other sources. The adipose derived stem cells (ADSCs) that it contains can be maintained and expanded in culture for long periods of time without losing their differentiation capacity, leading to large cell quantities being increasingly used in cell therapy purposes. Many reports showed that ADSCs-based cell therapy products demonstrated optimal efficacy and efficiency in some clinical indications for both autologous and allogeneic purposes, hence becoming considered as potential tools for replacing, repairing, and regenerating dead or damaged cells. In this review, we analyzed the therapeutic advancement of ADSCs in comparison to bone marrow (BM) and umbilical cord (UC)-mesenchymal stem cells (MSCs) and designed the specific requirements to their best clinical practices and safety. Our analysis was focused on the ADSCs, rather than the whole stromal vascular fraction (SVF) cell populations, to facilitate characterization that is related to their source of origins. Clinical outcomes improvement suggested that these cells hold great promise in stem cell-based therapies in neurodegenerative, cardiovascular, and auto-immunes diseases.

Regenerative Capacity of Adipose Derived Stem Cells (ADSCs), Comparison with Mesenchymal Stem Cells (MSCs)

Adipose tissue is now on the top one of stem cell sources regarding its accessibility, abundance, and less painful collection procedure when compared to other sources. The adipose derived stem cells (ADSCs) that it contains can be maintained and expanded in culture for long periods of time without losing their differentiation capacity, leading to large cell quantities being increasingly used in cell therapy purposes. Many reports showed that ADSCs-based cell therapy products demonstrated optimal efficacy and efficiency in some clinical indications for both autologous and allogeneic purposes, hence becoming considered as potential tools for replacing, repairing, and regenerating dead or damaged cells. In this review, we analyzed the therapeutic advancement of ADSCs in comparison to bone marrow (BM) and umbilical cord (UC)-mesenchymal stem cells (MSCs) and designed the specific requirements to their best clinical practices and safety. Our analysis was focused on the ADSCs, rather than the whole stromal vascular fraction (SVF) cell populations, to facilitate characterization that is related to their source of origins. Clinical outcomes improvement suggested that these cells hold great promise in stem cell-based therapies in neurodegenerative, cardiovascular, and auto-immunes diseases.

Spontaneously Formed Spheroids from Mouse Compact Bone-Derived Cells Retain Highly Potent Stem Cells with Enhanced Differentiation Capability

The results from our recent study showed the presence of two distinct spheroid-forming mechanisms, i.e., spontaneous and mechanical. In this study, we focused on the spontaneously formed spheroids, and the character of spontaneously formed spheroids from mouse compact bone-derived cells (CBDCs) was explored. Cells from (C57BL/6J) mouse leg bones were isolated, and compact bone-derived cells were cultured after enzymatic digestion. Spontaneous spheroid formation was achieved on a culture plate with specific water contact angle as reported. The expression levels of embryonic stem cell markers were analyzed using immunofluorescence and quantitative reverse transcription polymerase chain reaction. Then, the cells from spheroids were induced into osteogenic and neurogenic lineages. The spontaneously formed spheroids from CBDCs were positive for ES cell markers such as SSEA1, Sox2, Oct4, and Nanog. Additionally, the expressions of fucosyltransferase 4/FUT4 (SSEA1), Sox2, and Nanog were significantly higher than those in monolayer cultured cells. The gene expression of mesenchymal stem cell markers was almost identical in both spheroids and monolayer-cultured cells, but the expression of Sca-1 was higher in spheroids. Spheroid-derived cells showed significantly higher osteogenic and neurogenic marker expression than monolayer-cultured cells after induction. Spontaneously formed spheroids expressed stem cell markers and showed enhanced osteogenic and neurogenic differentiation capabilities than cells from the conventional monolayer culture, which supports the superior stemness.

Design of a Randomized Controlled Clinical Study of tissue-engineered osteogenic materials using bone marrow-derived mesenchymal cells for Maxillomandibular bone defects in Japan: the TEOM study protocol

Background

Maxillomandibular bone defects arise from maxillofacial injury or tumor/cyst removal. While the standard therapy for bone regeneration is transplantation with autologous bone or artificial bone, these therapies are still unsatisfactory. Autologous bone harvesting is invasive and occasionally absorbed at the implanted site. The artificial bone takes a long time to ossify and it often gets infected. Therefore, we have focused on regenerative therapy consisting of autologous bone marrow-derived mesenchymal cells (BM-MSCs), which decreases the burden on patients. Based on our previous research in patients with maxillomandibular bone defects or alveolar bone atrophy using a mixture of BM-MSCs, platelet-rich plasma (PRP), thrombin, and calcium, we confirmed the efficacy and acceptable safety profile of this treatment. In this investigator-initiated clinical study (the TEOM study), we intended to add β-tricalcium phosphate (β-TCP) owing to large defect with patients. The TEOM study aimed to evaluate the efficacy and safety of bone regeneration using mixtures of BM-MSCs in patients with bone defects resulting from maxillofacial injury, and tumor/cyst removal in the maxillomandibular region.

Methods

The TEOM study is an open-label, single-center, randomized controlled study involving a total of 83 segments by the Fédération Dentaire Internationale numbering system in maxillomandibular bone defects that comprise over 1/3 of the maxillomandibular area with a remaining bone height of ≤10 mm. The primary endpoint is rate of procedure sites with successful bone regeneration defined as a computed tomography (CT) value of more than 400 and a bone height of more than 10 mm. Our specific hypothesis is that the number of required regions was calculated assuming that the rate of procedure sites with successful bone regeneration is similar and the non-inferiority margin is 15.0%.

Discussion

The TEOM study is the first randomized controlled study of regenerative treatment using BM-MSCs for large maxillomandibular bone defects. We will evaluate the efficacy and safety in this study to provide an exploratory basis for the necessity of BM-MSCs for these patients.

Trial registration

This trial was registered at the University Hospital Medical information Network Clinical Trials Registry (UMIN-CTR Unique ID: UMIN000020398; Registration Date: Jan 15, 2016; URL: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000016543).

Clinical Potential and Current Progress of Dental Pulp Stem Cells for Various Systemic Diseases in Regenerative Medicine: A Concise Review

Dental pulp stem cells (DPSCs) are mesenchymal stem cells (MSCs) that have multipotent differentiation and a self-renewal ability. They have been useful not only for dental diseases, but also for systemic diseases. Extensive studies have suggested that DPSCs are effective for various diseases, such as spinal cord injuries, Parkinson's disease, Alzheimer's disease, cerebral ischemia, myocardial infarction, muscular dystrophy, diabetes, liver diseases, eye diseases, immune diseases, and oral diseases. DPSCs have the potential for use in a cell-therapeutic paradigm shift to treat these diseases. It has also been reported that DPSCs have higher regenerative potential than the bone marrow-derived mesenchymal stem cells known as representative MSCs. Therefore, DPSCs have recently gathered much attention. In this review, the therapeutic potential of DPSCs, the latest progress in the pre-clinical study for treatment of these various systemic diseases, and the clinical applications of DPSCs in regenerative medicine, are all summarized. Although challenges, including mechanisms of the effects and establishment of cell processing and transplantation methods for clinical use, still remain, DPSCs could be promising stem cells sources for various clinical applications, because of their easy isolation by a noninvasive procedure without ethical concerns.

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

Abstract 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.

Combination of polyetherketoneketone scaffold and human mesenchymal stem cells from temporomandibular joint synovial fluid enhances bone regeneration

Therapies using human mesenchymal stem cells (MSCs) combined with three-dimensional (3D) printed scaffolds are a promising strategy for bone grafting. But the harvest of MSCs still remains invasive for patients. Human synovial fluid MSCs (hSF-MSCs), which can be obtained by a minimally invasive needle-aspiration procedure, have been used for cartilage repair. However, little is known of hSF-MSCs in bone regeneration. Polyetherketoneketone (PEKK) is an attractive bone scaffold due to its mechanical properties comparable to bone. In this study, 3D-printed PEKK scaffolds were fabricated using laser sintering technique. hSF-MSCs were characterized and cultured on PEKK to evaluate their cell attachment, proliferation, and osteogenic potential. Rabbit calvarial critical-sized bone defects were created to test the bone regenerative effect of PEKK with hSF-MSCs. In vitro results showed that hSF-MSCs attached, proliferated, and were osteogenic on PEKK. In vivo results indicated that PEKK seeded with hSF-MSCs regenerated twice the amount of newly formed bone when compared to PEKK seeded with osteogenically-induced hSF-MSCs or PEKK scaffolds alone. These results suggested that there was no need to induce hSF-MSCs into osteoblasts prior to their transplantations in vivo. In conclusion, the combined use of PEKK and hSF-MSCs was effective in regenerating critical-sized bone defects.

Dental pulp stem cells in chitosan/gelatin scaffolds for enhanced orofacial bone regeneration

OBJECTIVE

Biomimetic chitosan/gelatin (CS/Gel) scaffolds have attracted great interest in tissue engineering of several tissues. However, limited information exists regarding the potential of combining CS/Gel scaffolds with oral cells, such as dental pulp stem cells (DPSCs), to produce customized constructs targeting alveolar/orofacial bone reconstruction, which has been the aim of the present study.

METHODS

Two scaffold types, designated as CS/Gel-0.1 and CS/Gel-1, were fabricated using 0.1 and 1% (v/v) respectively of the crosslinker glutaraldehyde (GTA). Scaffolds (n=240) were seeded with DPSCs with/without pre-exposure to recombinant human BMP-2. In vitro assessment included DPSCs characterization (flow cytometry), evaluation of viability/proliferation (live/dead staining, metabolic-based tests), osteo/odontogenic gene expression analysis (qRT-PCR) and structural/chemical characterization (scanning electron microscopy, SEM; energy dispersive X-ray spectroscopy, EDX; X-ray powder diffraction, XRD; thermogravimetry, TG). In vivo assessment included implantation of DPSC-seeded scaffolds in immunocompromised mice, followed by histology and SEM-EDX. Statistical analysis employed one/two-way ANOVA and Tukey's post-hoc tests (significance for p<0.05).

RESULTS

Both scaffolds supported cell viability/proliferation over 14 days in culture, showing extensive formation of a hydroxyapatite-rich nanocrystalline calcium phosphate phase. Differential expression patterns indicated GTA concentration to significantly affect the expression of osteo/odontogenic genes, with CS/Gel-0.1 scaffolds being more effective in upregulating DSPP, IBSP and Osterix. In vivo analysis demonstrated time-dependent production of a nanocrystalline, mineralized matrix at 6, 8 and 10 weeks, being more prominent in constructs bearing rhBMP-2 pre-treated cells. The latter showed higher amounts of osteoid and fully mineralized bone, as well as empty space reduction.

SIGNIFICANCE

These results reveal a promising strategy for orofacial bone tissue engineering.

Development of a micro-tissue-mediated injectable bone tissue engineering strategy for large segmental bone defect treatment

BACKGROUND

Bone tissue engineering is not widely used in clinical treatment. Two main reasons hide behind this: (1) the seed cells are difficult to obtain and (2) the process of tissue engineering bone construction is too complex and its efficiency is still relatively low. It is foreseeable that in the near future, the problem of seed cell sources could be solved completely in tissue engineering bone repair. As for the complex process and low efficiency of tissue engineering bone construction, usually two strategies would be considered: (1) the construction strategy based on injectable bone tissue and (2) the construction strategy based on osteogenic cell sheets. However, the application of injectable bone tissue engineering (iBTE) strategy and osteogenic cell sheet strategy is limited and they could hardly be used directly in repairing defects of large segmental bone, especially load-bearing bone.

METHODS

In this study, we built an osteogenic micro-tissue with simple construction but with a certain structure and composition. Based on this, we established a new iBTE repair strategy-osteogenic micro-tissue in situ repair strategy, mainly targeting at solving the problem of large segmental bone defect. The steps are as follows: (1) Build the biodegradable three-dimensional scaffold based on the size of the defect site with 3D printing rapid prototyping technology. (2) Implant the three-dimensional scaffold into the defect site. This scaffold is considered as the "steel framework" that could provide both mechanical support and space for bone tissue growth. (3) Inject the osteogenic micro-tissue (i.e., the "cell-extracellular matrix" complex), which could be considered as "concrete," into the three-dimensional scaffold, to promote the bone tissue regeneration in situ. Meanwhile, the digested cells were injected as the compared group in this experiment. After 3 months, the effect of in situ bone defect repair of osteogenic micro-tissue and digested cells was compared.

RESULTS

It is confirmed that osteogenic micro-tissue could achieve a higher efficiency on cell usage and has a better repair effect than the digested cells.

CONCLUSIONS

Osteogenic micro-tissue repairing strategy would be a more promising clinical strategy to solve the problem of large segmental bone defect.

Effects of physiological aging factor on bone tissue engineering repair based on fetal BMSCs

Background

At present, many laboratories and hospitals all over the world are attempting and exploring the clinical transformation of this tissue engineered bone graft (TEBG) strategy. Many successful cases of bone tissue engineering (BTE) repair were based on young individuals. But there are little studies about the effectiveness of TEBG strategy in physiological aged individuals.

Methods

In this research, we studied whether aging factor has influence on the skull repair effect of Fetal-TEBG, at the level of the large animal models. We used the fetal bone marrow stromal cells (Fetal-BMSCs) as the seed cells, combining the decalcified bone matrix (DBM) scaffolds, to repair the skull defects of the aged goats and the young goats. The repair effects on both aged goat and young goat were compared by Micro-CT and histology examination.

Results

The skull defects of the young goats could be repaired better than that of the aged goats after 6 months by Fetal-TEBG; In the aged goats, although not completely repaired, the defects repaired by Fetal-TEBG was better than that repaired by the Control DBM scaffold.

Conclusions

Aging factor has impact on the bone repair effect of Fetal-TEBG; and the BTE strategy is still efficacious even in the aged individuals. The improvement of the aged state may promote the repair effect of the BTE in the aged individuals.

Clinical Study of Bone Regeneration by Conditioned Medium From Mesenchymal Stem Cells After Maxillary Sinus Floor Elevation

OBJECTIVE

This clinical study was undertaken to evaluate the safety of use of the secretome of bone marrow-derived mesenchymal stem cells (MSC-CM) for maxillary sinus floor elevation (SFE).

MATERIALS AND METHODS

MSC-CM was prepared from conditioned medium from human bone marrow-derived MSCs. Six partially edentulous patients were enrolled in the study. MSC-CM was mixed with porous beta-tricalcium phosphate (β-TCP) and implanted in 4 patients (experimental group), whereas only β-TCP was implanted in the other 2 patients (control group). Six months after SFE, bone biopsies and histological assessments were performed.

RESULTS

Bone formation was clinically confirmed in all cases. Although Hounsfield units in computed tomography images were not significantly different between the groups, histological analysis revealed a significant difference in newly formed bone area between the groups. In particular, bone volume in the center of the augmented area was significantly greater in the MSC-CM group. Newly formed bone consisted of lamellar bone in the MSC-CM group but woven bone in the β-TCP group.

CONCLUSION

The secretome of bone marrow-derived mesenchymal stem cells (MSC-CM) was used safely and has great osteogenic potential for regenerative medicine of bone.

Cytokine Mixtures Mimicking Secretomes From Mesenchymal Stem Cells Improve Medication-Related Osteonecrosis of the Jaw in a Rat Model

Recently, several studies have demonstrated that intravenous administration of mesenchymal stem cells (MSCs) improve medication-related osteonecrosis of the jaw (MRONJ), and paracrine effects of secretomes from MSCs have been hypothesized as the primary contributors. These secretomes in conditioned media from human MSCs (MSC-CM) were previously demonstrated to promote bone and tissue regeneration. Because MSC-CM contain cytokines monocyte chemoattractant protein (MCP)-1, insulin growth factor (IGF)-1, and vascular endothelial growth factor (VEGF) at relatively higher concentrations than other factors, these cytokines were considered as relevant active factors for tissue regeneration. By mixing the recombinant proteins of MCP-1, IGF-1, and VEGF, included at the same concentrations in MSC-CM, we prepared cytokine mixtures mimicking MSC-CM and then evaluated its therapeutic effects in a rat MRONJ model. In vitro, cytokine mixtures promoted osteogenic differentiation, migration, and proliferation of rat MSCs. In addition, these maintained osteoclastic function. In vivo, we used a rat MRONJ model to examine therapeutic effects of the cytokine mixtures through intravenous administration. In MSC-CM or cytokine mixture group, open alveolar sockets in 66% or 67% of the rats with MRONJ, respectively, healed with complete soft tissue coverage and socket bones, whereas in the other groups, the exposed necrotic bone with inflamed soft tissue remained. Histological analysis revealed new bone formation and the appearance of osteoclasts in MSC-CM or cytokine mixture group; however, osteoclasts were significantly reduced in the other groups. Thus, we concluded that intravenous administration of cytokine mixtures might be an effective therapeutic modality for treating patients with MRONJ.

Strategies to retain properties of bone marrow-derived mesenchymal stem cells ex vivo

Mesenchymal stem cells (MSCs) have been extensively used for cell therapies and tissue engineering. The current MSC strategy requires a large quantity of cells for such applications, which can be achieved through cell expansion in culture. In the body, stem cell fate is largely determined by their microenvironment, known as the niche. The complex and dynamic stem cell niche provides physical, mechanical, and chemical cues to collaboratively regulate cell activities. It remains a great challenge to maintain the properties of MSCs in culture. Constructing a microenvironment as an engineered stem cell niche in culture to maintain MSC phenotypes, properties, and functions is a viable strategy to address the issue. Here, we review the current understanding of MSC behavior in the bone marrow niche, describe different strategies to engineer an in vitro microenvironment for maintaining MSC properties and functions, and discuss previous findings on environmental factors critical to the modulation of MSC activities in engineered microenvironments.

Efficacy of Humanized Mesenchymal Stem Cell Cultures for Bone Tissue Engineering: A Systematic Review with a Focus on Platelet Derivatives

Fetal bovine serum (FBS) is the most commonly used supplement for ex vivo expansion of human mesenchymal stem cells (hMSCs) for bone tissue engineering applications. However, from a clinical standpoint, it is important to substitute animal-derived products according to current good manufacturing practice (cGMP) guidelines. Humanized alternatives to FBS include three categories of products: human serum (HS), human platelet derivatives (HPDs)-including platelet lysate (PL) or platelet releasate (PR), produced by freeze/thawing or chemical activation of platelet concentrates, respectively, and chemically defined media (serum-free) (CDM). In this systematic literature review, the in vitro and in vivo osteogenic potential of hMSCs expanded in humanized (HS-, HPD-, or CDM-supplemented) media versus hMSCs expanded in FBS-supplemented media, was compared. In addition, PL and PR were compared in terms of their growth factor (GF)/cytokine-content and cell-culture efficacy. When using either 10-20% autologous or pooled HS, 3-10% pooled HPDs or CDM supplemented with GFs, in comparison with 10-20% FBS, a majority of studies reported similar or superior in vitro proliferation and osteogenic differentiation, and in vivo bone formation in ectopic or orthotopic rodent models. Moreover, a trend for higher GF content was observed in PL versus PR, although evidence for cell culture efficacy is limited. In summary, humanized supplements seem at least equally effective as FBS for hMSC expansion and osteogenic differentiation. Although pooled HPDs appear to be the most favorable supplement for large-scale hMSC expansion, further efforts are needed to standardize the preparation and composition of these products in compliance with cGMP standards.

Bone tissue engineering in oral peri-implant defects in preclinical in vivo research: A systematic review and meta-analysis

The regeneration and establishment of osseointegration within oral peri-implant bone defects remains a clinical challenge. Bone tissue engineering (BTE) is emerging as a promising alternative to autogenous and/or biomaterial-based bone grafting. The objective of this systematic review was to answer the focused question: in animal models, do cell-based BTE strategies enhance bone regeneration and/or implant osseointegration in experimental peri-implant defects, compared with grafting with autogenous bone or only biomaterial scaffolds? Electronic databases were searched for controlled animal studies reporting on peri-implant defects and implantation of mesenchymal stem cells (MSC) or other cells seeded on biomaterial scaffolds, following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Random effects meta-analyses were performed for the outcomes histomorphometric bone area fraction (BA) and bone-to-implant contact (BIC). Nineteen studies reporting on large animal models (dogs and sheep) were included. Experimental defects were created surgically (16 studies) or via ligature-induced peri-implantitis (LIPI, three studies). In general, studies presented with an unclear to high risk of bias. In most studies, MSC were used in combination with alloplastic mineral phase or polymer scaffolds; no study directly compared cell-loaded scaffolds vs. autogenous bone. In three studies, cells were also modified by ex vivo gene transfer of osteoinductive factors. The meta-analyses indicated statistically significant benefits in favour of: (a) cell-loaded vs. cell-free scaffolds [weighted mean differences (WMD) of 10.73-12.30% BA and 11.77-15.15% BIC] in canine surgical defect and LIPI models; and (b) gene-modified vs. unmodified cells (WMD of 29.44% BA and 16.50% BIC) in canine LIPI models. Overall, heterogeneity in the meta-analyses was high (I² 70-88%); considerable variation was observed among studies regarding the nature of cells and scaffolds used. In summary, bone regeneration and osseointegration in peri-implant defects are enhanced by the addition of osteogenic cells to biomaterial scaffolds. Although the direction of treatment outcome is clearly in favour of BTE strategies, due to the limited magnitude of treatment effect observed, no conclusive statements regarding the clinical benefit of such procedures for oral indications can yet be made. Copyright © 2017 John Wiley & Sons, Ltd.

Single cell biology beyond the era of antibodies: relevance, challenges, and promises in biomedical research

Research of the past two decades has proved the relevance of single cell biology in basic research and translational medicine. Successful detection and isolation of specific subsets is the key to understand their functional heterogeneity. Antibodies are conventionally used for this purpose, but their relevance in certain contexts is limited. In this review, we discuss some of these contexts, posing bottle neck for different fields of biology including biomedical research. With the advancement of chemistry, several methods have been introduced to overcome these problems. Even though microfluidics and microraft array are newer techniques exploited for single cell biology, fluorescence-activated cell sorting (FACS) remains the gold standard technique for isolation of cells for many biomedical applications, like stem cell therapy. Here, we present a comprehensive and comparative account of some of the probes that are useful in FACS. Further, we illustrate how these techniques could be applied in biomedical research. It is postulated that intracellular molecular markers like nucleostemin (GNL3), alkaline phosphatase (ALPL) and HIRA can be used for improving the outcome of cardiac as well as bone regeneration. Another field that could utilize intracellular markers is diagnostics, and we propose the use of specific peptide nucleic acid probes (PNPs) against certain miRNAs for cancer surgical margin prediction. The newer techniques for single cell biology, based on intracellular molecules, will immensely enhance the repertoire of possible markers for the isolation of cell types useful in biomedical research.

Angiogenesis in newly regenerated bone by secretomes of human mesenchymal stem cells

Background

For an effective bone graft for reconstruction of the maxillofacial region, an adequate vascular network will be required to supply blood, osteoprogenitor cells, and growth factors. We previously reported that the secretomes of bone marrow-derived mesenchymal stem cells (MSC-CM) contain numerous growth factors such as insulin-like growth factor (IGF)-1, transforming growth factor (TGF)-β1, and vascular endothelial growth factor (VEGF), which can affect the cellular characteristics and behavior of regenerating bone cells. We hypothesized that angiogenesis is an important step for bone regeneration, and VEGF is one of the crucial factors in MSC-CM that would enhance its osteogenic potential. In the present study, we focused on VEGF in MSC-CM and evaluated the angiogenic and osteogenic potentials of MSC-CM for bone regeneration.

Methods

Cytokines in MSC-CM were measured by enzyme-linked immunosorbent assay (ELISA). Human umbilical vein endothelial cells (HUVECs) were cultured with MSC-CM or MSC-CM with anti-VEGF antibody (MSC-CM + anti-VEGF) for neutralization, and tube formation was evaluated. For the evaluation of bone and blood vessel formation with micro-computed tomography (micro-CT) and for the histological and immunohistochemical analyses, a rat calvarial bone defect model was used.

Results

The concentrations of IGF-1, VEGF, and TGF-β1 in MSC-CM were 1515.6 ± 211.8 pg/mL, 465.8 ± 108.8 pg/mL, and 339.8 ± 14.4 pg/mL, respectively. Tube formation of HUVECs, bone formation, and blood vessel formation were increased in the MSC-CM group but decreased in the MSC-CM + anti-VEGF group. Histological findings suggested that new bone formation in the entire defect was observed in the MSC-CM group although it was decreased in the MSC-CM + anti-VEGF group. Immunohistochemistry indicated that angiogenesis and migration of endogenous stem cells were much more abundant in the MSC-CM group than in the MSC-CM + anti-VEGF group.

Conclusions

VEGF is considered a crucial factor in MSC-CM, and MSC-CM is proposed to be an adequate therapeutic agent for bone regeneration with angiogenesis.

Amniotic fluid-derived stem cells mixed with platelet rich plasma for restoration of rat alveolar bone defect

Stem cells isolated from the amniotic fluid have been shown as a promising candidate for cell therapy and tissue engineering. However, the experimental and preclinical applications of amniotic fluid-derived stem cells (AFSCs) in the very field of maxillofacial bone tissue engineering are still limited. In this study, rat AFSCs were successfully harvested and characterized in vitro. The rat AFSCs showed typical fibroblastoid morphology, stable proliferation activity and multi-differentiation potential. Flow-cytometry analysis demonstrated that these cells were positive for CD29, CD44, and CD90, while negative for hematopoietic markers such as CD34 and CD45. The regenerative performance of AFSCs-premixed with platelet rich plasma (PRP) gel in restoration of alveolar bone defect was further investigated using a modified rat maxillary alveolar defect model. Micro-computer tomography and histological examination showed a superior regenerative capacity of AFSCs-premixed with PRP gel at both 4 and 8 weeks after operation comparing with control groups. Moreover, the implanted AFSCs can survive in the defect site and directly participate in the bone tissue regeneration. Taken together, these results indicated the feasibility of an AFSCs-based alveolar bone tissue engineering strategy for alveolar defect restoration.

Low-serum culture with novel medium promotes maxillary/mandibular bone marrow stromal cell proliferation and osteogenic differentiation ability

OBJECTIVES

The purpose of this study was to evaluate the effect of low-serum STK2 medium on the isolation and osteogenic differentiation of human maxillary/mandibular bone marrow stromal cells (MBMSCs).

MATERIALS AND METHODS

Human MBMSCs were obtained from patients undergoing dental implant treatment. These cells were cultured in serum-free medium or STK2 medium containing 1  % fetal bovine serum (low-serum) or α-MEM containing 10  % fetal bovine serum (control). Proliferation on the culture surface, cell surface antigen expression, and mRNA levels of neural crest and osteogenic markers were examined. Alkaline phosphatase assay and Alizarin red staining were used to assess osteogenic differentiation potential. Immunoblotting analysis was performed to detect ERK phosphorylation.

RESULTS

Low-serum and control MBMSCs were positive for CD73, CD90, and CD105 and negative for CD14, CD34, CD45, CD271, and HLA-DR. CD140a was absent in low-serum cells but present in control cells. Low-serum MBMSCs proliferated more than control MBMSCs. After induction of osteogenic differentiation, alkaline phosphatase activity and osteocalcin mRNA levels were higher in low-serum MBMSCs than in control cells, and Alizarin red staining was stronger in low-serum MBMSCs than in control cells. Low-serum culture promoted ERK phosphorylation.

CONCLUSIONS

MBMSCs precultured in low-serum medium exhibited a greater cumulative cell number and a higher osteogenic differentiation capacity than those cultured in control medium.

CLINICAL RELEVANCE

These findings indicate that low-serum STK2 culture might be useful to promote MBMSC proliferation and osteogenic differentiation. This method requires less autologous blood collection for cell expansion than conventional methods, thus reducing the burden on patients.

A defined mix of cytokines mimics conditioned medium from cultures of bone marrow-derived mesenchymal stem cells and elicits bone regeneration

OBJECTIVES

We previously reported that conditioned medium from cultures of bone marrow-derived mesenchymal stem cells have strong potential to accelerate bone regeneration. We now examine in vitro and in vivo a defined cytokine cocktail that mimics the effects of conditioned medium on bone regeneration.

MATERIALS AND METHODS

A cocktail of recombinant human insulin-like growth factor-1, vascular endothelial growth factor-A and transforming growth factor-β1 was prepared at concentrations similar to those in conditioned medium. Conversely, these cytokines were depleted from conditioned medium, and the effects of the cocktail, the conditioned medium and the cytokine-depleted conditioned medium on bone regeneration were evaluated in vitro and in vivo.

RESULTS

The cytokine cocktail and conditioned medium enhanced cell migration, tube formation, and expression of osteogenic and angiogenic genes. Depletion of cytokines significantly decreased the effects of conditioned medium in vitro. Similarly, the cytokine cocktail and conditioned medium, but not cytokine-depleted medium, increased bone regeneration in damaged rat calvarial bone. Immunohistochemistry indicated that the cytokine cocktail and conditioned medium strongly enhanced recruitment of endogenous stem cells and endothelial cells.

CONCLUSIONS

The data indicate that the cytokine cocktail and conditioned medium enhance the migration of stem cells and endothelial cells to damaged bone, and elicit osteogenesis and angiogenesis.

Periostin Upregulates Wnt/β-Catenin Signaling to Promote the Osteogenesis of CTLA4-Modified Human Bone Marrow-Mesenchymal Stem Cells

The enhanced osteogenesis of mesenchymal stem cells (MSCs) modified by expression of cytotoxic T lymphocyte-associated antigen 4 (CTLA4) has been shown in previous studies, but the mechanism remains unknown. Here we found that the bone repair effect of CTLA4-modified MSCs in demineralized bone matrix (DBM) in a rabbit radius defect model was significantly better than that observed for unmodified MSCs in DBM or DBM alone, and the periostin (POSTN) expression in CTLA4-modified MSCs was significantly higher than that in unmodified MSCs both in vivo and in vitro. In addition, we also found that treatment of CTLA4-modified MSCs with soluble POSTN could inhibit the glycogen synthase kinase-3β activity and increase β-catenin expression through up-regulation of lipoprotein-related protein-6 phosphorylation to promote osteogenic differentiation, but blocking of integrin αvβ3, a receptor of POSTN, could suppress these effects. Our data demonstrated that POSTN expressed in response to CTLA4 can promote the osteogenesis of xenotransplanted MSCs through interaction with Wnt/β-catenin pathway.

Phase I/II Trial of Autologous Bone Marrow Stem Cell Transplantation with a Three-Dimensional Woven-Fabric Scaffold for Periodontitis

Regenerative medicine is emerging as a promising option, but the potential of autologous stem cells has not been investigated well in clinical settings of periodontal treatment. In this clinical study, we evaluated the safety and efficacy of a new regenerative therapy based on the surgical implantation of autologous mesenchymal stem cells (MSCs) with a biodegradable three-dimensional (3D) woven-fabric composite scaffold and platelet-rich plasma (PRP). Ten patients with periodontitis, who required a surgical procedure for intrabony defects, were enrolled in phase I/II trial. Once MSCs were implanted in each periodontal intrabony defect, the patients were monitored during 36 months for a medical exam including laboratory tests of blood and urine samples, changes in clinical attachment level, pocket depth, and linear bone growth (LBG). All three parameters improved significantly during the entire follow-up period (p < 0.0001), leading to an average LBG of 4.7 mm after 36 months. Clinical mobility measured by Periotest showed a decreasing trend after the surgery. No clinical safety problems attributable to the investigational MSCs were identified. This clinical trial suggests that the stem cell therapy using MSCs-PRP/3D woven-fabric composite scaffold may constitute a novel safe and effective regenerative treatment option for periodontitis.

Emerging regenerative approaches for periodontal reconstruction: a systematic review from the AAP Regeneration Workshop

More than 30 years have passed since the first successful application of regenerative therapy for treatment of periodontal diseases. Despite being feasible, periodontal regeneration still faces numerous challenges, and complete restoration of structure and function of the diseased periodontium is often considered an unpredictable task. This review highlights developing basic science and technologies for potential application to achieve reconstruction of the periodontium. A comprehensive search of the electronic bibliographic database PubMed was conducted to identify different emerging therapeutic approaches reported to influence either biologic pathways and/or tissues involved in periodontal regeneration. Each citation was assessed based on its abstract, and the full text of potentially eligible reports was retrieved. Based on the review of the full papers, their suitability for inclusion in this report was determined. In principle, only reports from scientifically well-designed studies that presented preclinical in vivo (animal studies) or clinical (human studies) evidence for successful periodontal regeneration were included. Hence, in vitro studies, namely those conducted in laboratories without any live animals, were excluded. In case of especially recent and relevant reviews with a narrow focus on specific regenerative approaches, they were identified as such, and thereby the option of referring to them to summarize the status of a specific approach, in addition to or instead of listing each separately, was preserved. Admittedly, the presence of subjectivity in the selection of studies to include in this overview cannot be excluded. However, it is believed that the contemporary approaches described in this review collectively represent the current efforts that have reported preclinical or clinical methods to successfully enhance regeneration of the periodontium. Today's challenges facing periodontal regenerative therapy continue to stimulate important research and clinical development, which, in turn, shapes the current concept of periodontal tissue engineering. Emerging technologies--such as stem cell therapy, bone anabolic agents, genetic approaches, and nanomaterials--also offer unique opportunities to enhance the predictability of current regenerative surgical approaches and inspire development of novel treatment strategies.

Stem Cell Therapy: Current Applications and Potential for Urology

Stem cell therapy holds the potential to revolutionize the treatment of a number of chronic conditions. Stem cells ability to home in on injured sites of the body, stimulate angiogenesis, tissue regeneration, immunomodulation, anti-inflammatory, and anti-fibrotic factors have attracted their use in the treatment of many conditions. Urology has registered one of the highest experimental successes using stem cell therapy. However, the rate of clinical applications is comparatively lower. This review takes a look at our efforts so far and what needs to be done in order to maximize the clinical benefit we can derive from stem cells.

Stem cells, growth factors and scaffolds in craniofacial regenerative medicine

Current reconstructive approaches to large craniofacial skeletal defects are often complicated and challenging. Critical-sized defects are unable to heal via natural regenerative processes and require surgical intervention, traditionally involving autologous bone (mainly in the form of nonvascularized grafts) or alloplasts. Autologous bone grafts remain the gold standard of care in spite of the associated risk of donor site morbidity. Tissue engineering approaches represent a promising alternative that would serve to facilitate bone regeneration even in large craniofacial skeletal defects. This strategy has been tested in a myriad of iterations by utilizing a variety of osteoconductive scaffold materials, osteoblastic stem cells, as well as osteoinductive growth factors and small molecules. One of the major challenges facing tissue engineers is creating a scaffold fulfilling the properties necessary for controlled bone regeneration. These properties include osteoconduction, osetoinduction, biocompatibility, biodegradability, vascularization, and progenitor cell retention. This review will provide an overview of how optimization of the aforementioned scaffold parameters facilitates bone regenerative capabilities as well as a discussion of common osteoconductive scaffold materials.

First-in-human study and clinical case reports of the alveolar bone regeneration with the secretome from human mesenchymal stem cells

BACKGROUND

Secreted growth factors and cytokines in the conditioned medium from bone marrow-derived mesenchymal stem cells (MSC-CM) have several effects on cell behavior. Our previous studies revealed that MSC-CM enhances bone regeneration by increasing cell mobilization, angiogenesis, and osteogenesis in vitro and in vivo. This clinical study was undertaken to evaluate the safety and use of MSC-CM for alveolar bone regeneration in eight patients who were diagnosed as needing bone augmentation prior to dental implant placement.

METHODS

The protocol of this clinical study was approved by the ethics committee of Nagoya University Hospital. MSC-CM was prepared from conditioned medium from commercially available human bone marrow-derived MSCs. Patients were treated with beta-tricalcium phosphate (β-TCP) or an atelocollagen sponge soaked with MSC-CM. Clinical and radiographic assessments were performed during the follow-up period. Histological assessments were also performed in some cases. Clinical and histological data from patients who underwent the SFE procedure without MSC-CM were also used retrospectively as reference controls.

RESULTS

MSC-CM contained several cytokines such as insulin-like growth factor-1, vascular endothelial growth factor, transforming growth factor-β1, and hepatocyte growth factor in relatively low amounts. No systemic or local complications were reported throughout the study. Radiographic evaluation revealed early bone formation in all cases. Histological evaluation also supported the radiographic findings. Furthermore, infiltration of inflammatory cells was scarce throughout the specimens.

CONCLUSIONS

MSC-CM was used safely and with less inflammatory signs and appears to have great osteogenic potential for regenerative medicine of bone. This is the first in-human clinical study of alveolar bone regeneration using MSC-CM.

Potential for Stem Cell-Based Periodontal Therapy

Periodontal diseases are highly prevalent and are linked to several systemic diseases. The goal of periodontal treatment is to halt the progression of the disease and regenerate the damaged tissue. However, achieving complete and functional periodontal regeneration is challenging because the periodontium is a complex apparatus composed of different tissues, including bone, cementum, and periodontal ligament. Stem cells may represent an effective therapeutic tool for periodontal regeneration due to their plasticity and their ability to regenerate different tissues. This review presents and critically analyzes the available information on stem cell-based therapy for the regeneration of periodontal tissues and suggests new avenues for the development of more effective therapeutic protocols.

Secreted Frizzled-Related Protein Promotes Bone Regeneration by Human Bone Marrow-Derived Mesenchymal Stem Cells

Secreted frizzled-related protein (sFRP)-3 is a negative regulator of Wnt signaling in human mesenchymal stem cells (hMSCs). The present study investigated the effects sFRP-3 on osteogenic differentiation by assessing osteogenic gene expression in hMSCs in vitro and by examining bone regeneration in a rat bone defect model. sFRP-3 treatment induced osteogenic differentiation in hMSCs as determined by alkaline phosphatase, collagen type I, osteocalcin, and Runt-related transcription factor 2 gene expression. hMSCs with or without sFRP-3 were implanted into a rat calvarial bone defect; a radiographic analysis by micro-computed tomography and histological analysis 4 and 8 weeks after implantation showed greater bone regeneration in the sFRP(+) than in the sFRP(−) group. These results suggest that modulation of Wnt signaling contributes to osteogenic differentiation in hMSCs. Specifically, sFRP-3 induces osteoblastic differentiation of cultured MSCs and bone regeneration in a calvarial bone defect, suggesting that it can be a useful agent for the treatment of bone defects.