Neuropilin Controls Endothelial Differentiation by Mesenchymal Stem Cells From the Periodontal Ligament

Background: Periodontal ligament (PDL) has been reported to be a source of mesenchymal stem cells (MSCs).New vascular networks from undifferentiated cells are essential for repair/regeneration of specialized tissues, including PDL. The current study aims to determine potential of CD105⁺‐enriched cell subsets of periodontal ligament cells (PDLSCs) to differentiate into endothelial cell (EC)‐like cells and to give insights into the mechanism involved. Methods: CD105⁺‐enriched PDLSCs were induced to EC differentiation by endothelial growth medium 2 (EGM‐2) for 3, 7, 14, and 21 days, with mRNA/protein levels and functional activity assessed by: 1) real‐time polymerase chain reaction; 2) Western blotting; 3) fluorescence‐activated cell sorting; 4) immunohistochemistry; 5) immunofluorescence; 6) matrigel; and 7) small interfering RNA assays. Results: Data analyses demonstrated that EGM‐2 treated PDLSCs presented increased expression of EC markers, including: 1) CD105; 2) kinase domain‐containing receptor; and 3) Ulex europaeus agglutinin 1, and were able to form cord/tube‐like structures. Gene and protein expression analysis showed that neuropilin 2 (NRP2), a key factor for vascular development, was significantly downregulated during EC differentiation. NRP2 was constitutively expressed in mouse PDL tissues by immunohistochemistry analysis, and NRP2 knockdown in CD105⁺‐enriched PDLSCs resulted in increased cord/tube‐like structures in a matrigel assay. Conclusion: These findings demonstrated the potential of CD105⁺‐enriched PDLSCs to support angiogenesis, and NRP2 as a pivotal factor regulating this process.     

In Vitro Study on Regeneration of Periodontal Tissue Microvasculature Using Human Dedifferentiated Fat Cells

Background: Human dedifferentiated fat cells (HDFATs) may be a new cell type suitable for regenerative therapies. The aim of this study is to assess the potential of HDFATs for vascular regeneration of periodontal tissue. To do this, HDFATs and human gingival endothelial cells (HGECs) were cocultivated, and vascular regeneration was examined in vitro. Methods: HDFATs were isolated from subcutaneous adipose tissue, and HGECs were isolated from gingival cells using anti‐cluster of differentiation 31 antibody‐coated magnetic beads. HDFATs were cocultured with HGECs in microvascular endothelial cell growth medium‐2 (EGM‐2MV) for 7 days. Expression of endothelial cell (EC) markers, the formation of capillary‐like tubes, and the expression of pericyte markers were determined. Results: HDFATs, cultured in EGM‐2MV or cocultured with HGECs, expressed EC markers. HDFATs in both conditions initiated tube formation within 5 hours of seeding and formed extensive capillary‐like structures within 12 hours. These structures disintegrated within 24 hours when cells were cultured in EGM‐2MV alone, whereas cocultured HDFATs maintained tubes for >24 hours. Cocultured HDFATs significantly increased expression of pericyte markers, a cell type associated with microvasculature. Conclusion: HDFATs possess the ability to express EC markers, and coculture with HGECs promotes differentiation into pericytes involved in the maturation and stabilization of the microvasculature.     

年龄因素对人牙周膜干细胞培养和性能的影响

目的:探讨年龄因素对人牙周膜干细胞(periodontal ligament stem cells,PDLSCs)体外培养及其生物学特性的影响。方法:收集临床<30岁、>50岁具有完整牙根的第三磨牙各4个,分别刮取根面残留牙周膜进行PDLSCs分离培养,观察其细胞克隆形成能力、MTT方法检测生长曲线、流式细胞仪分析细胞表面分子,并进行体外成骨、成脂诱导,对比分析PDLSCs多向分化能力。结果:两组第三磨牙中均可培养出具有明显间充质干细胞(mesenchymal stem cell,MSC)特性的PDLSCs,但>50岁组获得的PDLSCs克隆形成率显著降低(P<0.05),其增殖、分化能力亦较<30岁组明显减弱(P<0.05)。结论:年龄因素对PDLSCs体外培养及其生物学特性具有明显影响;PDLSCs的基础和临床研究中,应充分考虑到病人年龄因素。     

Stromal cell-derived factor-1 significantly induces proliferation, migration, and collagen type I expression in a human periodontal ligament stem cell subpopulation

Background: The pivotal role of chemokine stromal cell–derived factor‐1 (SDF‐1) in bone marrow mesenchymal stem cells recruitment and tissue regeneration has already been reported. However, its roles in human periodontal ligament stem cells (PDLSCs) remain unknown. PDLSCs are regarded as candidates for periodontal tissue regeneration and are used in stem cell–based periodontal tissue engineering. The expression of chemokine receptors on PDLSCs and the migration of these cells induced by chemokines and their subsequent function in tissue repair may be a crucial procedure for periodontal tissue regeneration. Methods: PDL tissues were obtained from clinically healthy premolars extracted for orthodontic reasons and used to isolate single‐cell colonies by the limited‐dilution method. Immunocytochemical staining was used to detect the expression of the mesenchymal stem cell marker STRO‐1. Differentiation potentials were assessed by alizarin‐red staining and oil‐red O staining. The expression of SDF‐1 receptor CXCR4 was evaluated by real‐time polymerase chain reaction (PCR) and immunocytochemical staining. 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay and bromodeoxyuridine incorporation assay were used to determine the viability and proliferation of the PDLSC subpopulation. Expression of collagen type I and alkaline phosphatase was detected by real‐time PCR to determine the effect of SDF‐1 on cells differentiation. Results: Twenty percent of PDL single‐cell colonies expressed STRO‐1 positively, and this specific subpopulation was positive for CXCR4 and formed minerals and lipid vacuoles after 4 weeks induction. SDF‐1 significantly increased proliferation and stimulated the migration of this PDLSC subpopulation at concentrations between 100 and 400 ng/mL. CXCR4 neutralizing antibody could block cell proliferation and migration, suggesting that SDF‐1 exerted its effects on cells through CXCR4. SDF‐1 promoted collagen type I level significantly but had little effect on alkaline phosphatase level. Conclusion: SDF‐1 may have the potential of promoting periodontal tissue regeneration by the mechanism of guiding PDLSCs to destructive periodontal tissue, promoting their activation and proliferation and influencing the differentiation of these stem cells.     

Establishing a technique for isolation and characterization of human periodontal ligament derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are extensively used in tissue regenerative procedures. One source of MSCs is the periodontal ligament (PDL) of teeth. Isolation of MSCs from extracted teeth is reasonably simple, being less invasive and presenting fewer ethical concerns than does the harvesting of MSC’s from other sites. The objectives of this study were to isolate and characterize the PDL stem cells (PDLSC) from healthy adults’ extracted teeth and then to characterize them by comparing them with bone-marrow derived MSCs (BMMSC).MethodsThe PDL tissue was scraped from the roots of freshly extracted teeth to enzymatically digest using collagenase. The cells were sub-cultured. Flow-cytometric analysis for the MSC surface-markers CD105, CD73, CD166, CD90, CD34, CD45 and HLA-DR was performed. To confirm the phenotype, total RNA was extracted to synthesize cDNA and which was then subjected to RT-PCR. The gene-expression for Oct4A, Sox2, NANOG and GAPDH was determined by gel-electrophoresis. To assess their multilineage potential, cells were cultured with osteogenic, chondrogenic and adipogenic medium and then stained by Alizarin-red, Alcian-blue and Oil-Red-O respectively. MSCs from the bone-marrow were processed similarly to serve as controls.ResultsThe cells isolated from extracted teeth expanded successfully. On flow-cytometric analysis, the cells were positive for CD73, CD90, CD105, CD166 and negative for CD34, CD45 and HLA-DR. The PDLSCs expressed Oct4A, Sox2, and NANOG mRNA with GAPDH expression. Cells cultured in the osteogenic, chondrogenic and adipogenic media stained positive for Alizarin-red, Alcian-blue and Oil- Red-O respectively. The surface marker expression and the trilineage differentiation characteristics were comparable to those of the BMMSCs.ConclusionsThe periodontal ligament tissue of extracted teeth is a potential source of therapeutically useful MSCs. Harvesting them is not invasive and are a promising source of MSC as the PDLSCs showed characteristics similar to those of the highly regarded MSC’s derived from bone-marrow.     

Stem cell properties of human periodontal ligament cells

BACKGROUND AND OBJECTIVE: Stem cells have been used for regenerative therapies in various fields. The proportion of cells that possess stem cell properties in human periodontal ligament (PDL) cells is not yet well understood. In this study, we quantitatively characterized human PDL cells to clarify their stem cell properties, including self-renewal, multipotency, and stem cell marker expression. MATERIAL AND METHODS: PDL cells were obtained from extracted premolar or wisdom teeth, following which a proliferation assay for self-renewal, a differentiation assay for multipotency, immunostaining for STRO-1, and fluorescence-activated cell sorter (FACS) analysis for stem cell markers (including CD105, CD166, and STRO-1) were performed. RESULTS: Approximately 30% of 400 PDL cells were found to possess replicative potential and formed single-cell colonies, and 30% of these colonies displayed positive staining for STRO-1, 20% differentiated into adipocytes and 30% differentiated into osteoblasts. FACS analysis revealed that PDL cells, including cell populations, expressed the stem cell markers CD105, CD166, and STRO-1. CONCLUSION: The findings of this study indicated that PDL cells possess crucial stem cell properties, such as self-renewal and multipotency, and express the mesenchymal stem cell markers CD105, CD166, and STRO-1 on their cell surface, although there were some variations. Thus, PDL cells can be used for periodontal regenerative procedures.     

Apical tooth germ cell-conditioned medium enhances the differentiation of periodontal ligament stem cells into cementum/periodontal ligament-like tissues

Background and Objective: Limitations of current periodontal regeneration modalities in both predictability and extent of healing response, especially on new cementum and attachment formation, underscore the importance of restoring or providing a microenvironment that is capable of promoting the differentiatiation of periodontal ligament stem cells (PDLSCs) towards cementoblast‐like cells and the formation of cementum/periodontal ligament‐like tissues. The aim of this study was to investigate the biological effect of conditioned medium from developing apical tooth germ cells (APTG‐CM) on the differentiation and cementogenesis of PDLSCs both in vitro and in vivo. Material and Methods: Using the limiting dilution technique, single‐colony‐derived human PDLSCs were isolated and expanded to obtain homogeneous populations of PDLSCs. Morphological appearance, cell cycle analysis, bromodeoxyuridine incorporation, alkaline phosphatase (ALP) activity, mineralization behavior, gene expression of cementoblast phenotype and in vivo differentiation capacities of PDLSCs co‐cultured with APTG‐CM were evaluated. Results: The induced PDLSCs exhibited several characteristics of cementoblast lineages, as indicated by the morphological changes, increased proliferation, high ALP activity, and the expression of cementum‐related genes and calcified nodule formation in vitro. When transplanted into immunocompromised mice, the induced PDLSCs showed tissue‐regenerative capacity to produce cementum/periodontal ligament‐like structures, characterized by a layer of cementum‐like mineralized tissues and associated periodontal ligament‐like collagen fibers connecting with the newly formed cementum‐like deposits, whereas control, untreated PDLSCs transplants mainly formed connective tissues. Conclusion: Our findings suggest that APTG‐CM is able to provide a cementogenic microenvironment and induce differentiation of PDLSCs along the cementoblastic lineage. This has important implications for periodontal engineering.     

Comparison of the properties of human CD146+ and CD146− periodontal ligament cells in response to stimulation with tumour necrosis factor α

ObjectivesPeriodontal ligament stem cells (PDLSCs) can be used in periodontal regeneration. Tumour necrosis factor-alpha (TNF-α) participates in the regulation of cell proliferation, apoptosis, differentiation, and migration. However, whether TNF-α can affect the biological features of PDLSCs is still unclear. The objective of this study was to illustrate the biological effects (proliferation, apoptosis, osteogenesis and migration) of TNF-α on human CD146 positive periodontal ligament cells (CD146+PLDCs) and CD146 negative periodontal ligament cells (CD146?PDLCs).MethodsCD146 ± PDLCs were isolated from human PDLCs and analyzed using a fluorescence-activated cell sorter. The biological effects of TNF-α on CD146 ± PDLCs were evaluated by CCK-8 assay (proliferation), DAPI staining (apoptosis), alizarin red staining and alkaline phosphatase activities assay (osteogenesis), and wounding assay and transwell assay (migration).ResultsCD146+PDLCs, which expressed MSC surface markers CD105, CD90, CD73, CD44, and Stro-1, showed higher proliferative and osteogenic potential than CD146?PDLCs. TNF-α at a dose of 2.5 ng/ml was found to enhance both proliferation and osteogenesis in CD146+PDLCs. At 5 ng/ml, TNF-α promoted proliferation, osteogenesis, and apoptosis in CD146+PDLCs and enhanced osteogenesis in CD146?PDLCs. At 10 ng/ml, TNF-α only aggravated apoptosis in CD146+PDLCs. The migratory ability of both CD146+PDLCs and CD146?PDLCs was not altered by TNF-α.ConclusionsCD146+PDLCs were subpopulation of MSC. It showed greater proliferative and osteogenic potential than CD146?PDLCs. At low concentration, TNF-α was beneficial to CD146+PDLCs on proliferation and osteogenesis, and at high concentration it was detrimental. CD146?PDLCs were found to be less sensitive to TNF-α.     

In Vitro Analysis of Human Periodontal Microvascular Endothelial Cells

Background: Endothelial cells (ECs) participate in key aspects of vascular biology, such as maintenance of capillary permeability, initiation of coagulation, and regulation of inflammation. According to previous reports, ECs have revealed highly specific characteristics depending on the organs and tissues. However, some reports have described the characteristics of the capillaries formed by human periodontal ECs. Therefore, the aim of the present study is to examine the functional characteristics of the periodontal microvascular ECs in vitro. Methods: Human periodontal ligament‐endothelial cells (HPDL‐ECs) and human gingiva‐endothelial cells (HG‐ECs) were isolated by immunoprecipitation with magnetic beads conjugated to a monoclonal anti‐CD31 antibody. The isolated HPDL‐ECs and HG‐ECs were characterized to definitively demonstrate that these cell cultures represented pure ECs. Human umbilical‐vein ECs and human dermal microvascular ECs were used for comparison. These cells were compared according to the proliferation potential, the formation of capillary‐like tubes, the transendothelial electric resistance (TEER), and the expression of tight junction proteins. Results: HPDL‐ECs and HG‐ECs with characteristic cobblestone monolayer morphology were obtained, as determined by light microscopy at confluence. Furthermore, the HPDL‐ECs and HG‐ECs expressed the EC markers platelet endothelial cell adhesion molecule‐1 (also known as CD31), von Willebrand factor, and Ulex europaeus agglutinin 1, and the cells stained strongly positive for CD31 and CD309. In addition, the HPDL‐ECs and HG‐ECs were observed to form capillary‐like tubes, and they demonstrated uptake of acetylated low‐density lipoprotein. Functional analyses of the HPDL‐ECs and HG‐ECs showed that, compared to the control cells, tube formation persisted for only a brief period of time, and TEER was substantially reduced at confluence. Furthermore, the cells exhibited delocalization of zonula occludens‐1 and occludin at cell–cell contact sites. Conclusions: The present results provide new evidence that HPDL‐ECs and HG‐ECs have characteristics of fenestrated capillaries. Therefore, capillaries in human periodontal tissues have functional characteristics of fenestrated capillaries, which might be related to the onset and the progression of systemic diseases and inflammation.     

LncRNA MAFG‐AS1 regulates human periodontal ligament stem cell proliferation and Toll‐like receptor 4 expression

LncRNA MAFG‐AS1 is predicted to interact with miR‐146a, which can target Toll‐like receptor 4 (TLR4), a key player in periodontitis. This study aimed to investigate the roles of MAFG‐AS1 in periodontitis. It was observed that MAFG‐AS1 was downregulated in the human periodontal ligament stem cells (PDLSCs) derived from periodontitis‐affected teeth. Dual‐luciferase assay revealed that co‐transfection of MAFG‐AS1 expression vector and miR‐146a mimic showed significantly lower relative luciferase activity comparing to co‐transfection of MAFG‐AS1 expression vector and negative control (NC) miRNA. However, MAFG‐AS1 and miR‐146a failed to affect each other. Interestingly, MAFG‐AS1 overexpression led to the upregulated TLR4. In addition, MAFG‐AS1 overexpression also led to the inhibited proliferation of PDLSCs. Therefore, MAFG‐AS1 may regulate the proliferation of PDLSCs and the expression of TLR4 to participate in periodontitis.     

Aspirin Enhances Osteogenic Potential of Periodontal Ligament Stem Cells (PDLSCs) and Modulates the Expression Profile of Growth Factor–Associated Genes in PDLSCs

Background: This study investigates the effects of aspirin (ASA) on the proliferative capacity, osteogenic potential, and expression of growth factor–associated genes in periodontal ligament stem cells (PDLSCs). Methods: Mesenchymal stem cells (MSCs) from PDL tissue were isolated from human premolars (n = 3). The MSCs’ identity was confirmed by immunophenotyping and trilineage differentiation assays. Cell proliferation activity was assessed through 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Polymerase chain reaction array was used to profile the expression of 84 growth factor–associated genes. Pathway analysis was used to identify the biologic functions and canonic pathways activated by ASA treatment. The osteogenic potential was evaluated through mineralization assay. Results: ASA at 1,000 μM enhances osteogenic potential of PDLSCs. Using a fold change (FC) of 2.0 as a threshold value, the gene expression analyses indicated that 19 genes were differentially expressed, which includes 12 upregulated and seven downregulated genes. Fibroblast growth factor 9 (FGF9), vascular endothelial growth factor A (VEGFA), interleukin‐2, bone morphogenetic protein‐10, VEGFC, and 2 (FGF2) were markedly upregulated (FC range, 6 to 15), whereas pleotropin, FGF5, brain‐derived neurotrophic factor, and Dickkopf WNT signaling pathway inhibitor 1 were markedly downregulated (FC 32). Of the 84 growth factor–associated genes screened, 35 showed high cycle threshold values (≥35). Conclusions: ASA modulates the expression of growth factor–associated genes and enhances osteogenic potential in PDLSCs. ASA upregulated the expression of genes that could activate biologic functions and canonic pathways related to cell proliferation, human embryonic stem cell pluripotency, tissue regeneration, and differentiation. These findings suggest that ASA enhances PDLSC function and may be useful in regenerative dentistry applications, particularly in the areas of periodontal health and regeneration.     

A Synthetic Oligopeptide Derived From Enamel Matrix Derivative Promotes the Differentiation of Human Periodontal Ligament Stem Cells Into Osteoblast‐Like Cells With Increased Mineralization

Background: In a previous study, the authors obtained a synthetic peptide (SP) for useful periodontal tissue regeneration. Periodontal ligament stem cells (PDLSCs) have multiple potentiality to contribute to tissue regeneration. The aim of this experiment is to investigate the effect of SP on human PDLSCs. Methods: Periodontal ligament cells were obtained from healthy adult human third molars and used to isolate single PDLSC‐derived colonies. The mesenchymal stem cell nature of the PDLSCs was confirmed by immunohistochemical evaluation of STRO‐1 expression. Proliferation and osteoblastic differentiation were investigated by culturing PDLSCs in normal or osteogenic medium with and without SP (100 ng/mL). Osteoblast differentiation was assessed by measuring alkaline phosphatase (ALP) activity, osteocalcin production, mRNA expression of osteonectin, mineralization, and calcium deposition. Results: Isolated PDLSCs were immunohistochemically positive for vimentin and STRO‐1 and negative for cytokeratin. A greater number of calcified nodules were observed in osteogenic medium culture with SP than without. In the early and later stages of PDLSC culture with SP, osteonectin production and osteocalcin production were increased. SP in culture with osteogenic medium significantly enhanced proliferation of PDLSCs, as well as ALP activity, expression of osteonectin, osteocalcin production, formation of calcified nodules, and mineralization. Conclusions: SP enhances the formation of calcified nodules and osteocalcin production in the culture of PDLSCs into osteoblast‐like cells and is a useful material for periodontal tissue regeneration.     

Characterization and evaluation of ascorbic acid-induced cell sheet formation in human periodontal ligament stem cells: An in vitro study

ObjectivesPeriodontal ligament-derived stem cells (PDLSCs) are regarded as a viable option for periodontal regeneration using cell sheet technology. The objective of the present in vitro study was to characterize human PDLSCs based on their phenotypic and biological properties and to evaluate the ascorbic acid (AA or vitamin C)-induced cell sheet by analyzing the molecular markers.MethodsPDLSCs were established from premolars, and their morphology, viability, proliferation, phenotypic marker expression, and ability to differentiate into osteocytes and adipocytes were analyzed. PDLSCs were then induced to form cell sheets using 100 μM AA, and gene expression was examined by real-time polymerase chain reaction.ResultsPDLSCs showed fibroblastic morphology with >95% viability. The cells were highly proliferative and positive for surface antigens CD29, CD73, and CD90 but negative for CD34 and CD45. They were capable of differentiating into osteocytes and adipocytes. Induction with 100 μM AA transformed PDLSCs into two-to three-layered cell sheets. There was no significant upregulation in ALP and RUNX2 expression in the AA-induced cell sheet. However, the expression levels of late osteoblast differentiation marker (bone gamma-carboxy glutamate protein); cementogenic markers (cementum attachment protein and CP23), and genes encoding extracellular matrix (ECM) proteins [collagen type 1 alpha 1 and integrin beta 1) were higher in AA-induced cell sheets by PDLSCs.ConclusionsThe stimulating effect of AA on cell sheet formation by PDLSCs was confirmed by the expression of typical markers involved in osteogenesis/cementogenesis and ECM secretion, which makes this procedure a prospective option for periodontal tissue regeneration applications.     

Effect of leptin on differentiation of human dental stem cells

Oral Diseases (2011) 17 , 662–669 Objectives: Mesenchymal stem cells (MSCs) were identified in adult human periodontal ligament and dental pulp that are considered as potential stem cell sources for future clinical applications in dentistry. Leptin is known as an important regulator of mesenchymal differentiation. The objective of this study was to elucidate the role of leptin on proliferation and differentiation of dental MSCs. Materials and methods: Enhancement of cemento/odontoblastic differentiation of dental stem cells by leptin was confirmed by alizarin red S staining and alkaline phosphatase activity staining. In contrast, leptin reduced adipogenesis in both dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) confirmed by oil red O staining and RT‐PCR. The expression of adipogenic markers, lipoprotein lipase and proliferator‐activated receptor γ2 (PPARγ2), were suppressed in PDLSCs incubated on media supplemented with leptin for 2 weeks. Results: Leptin had a relatively stronger osteogenesis promoting effect and adipogenesis suppressing effect in PDLSCs than in DPSCs. Conclusions: Collectively, leptin had a relatively stronger promoting effect on cemento/odontoblastic differentiation and a suppressing effect on adipogenesis in PDLSCs than in DPSCs. This study has provided evidence that leptin acts as an important modulator of dental MSCs differentiation.     

Efficacy of stem cells on periodontal regeneration: Systematic review of pre‐clinical studies

This systematic review aims to evaluate mesenchymal stem cells (MSC) periodontal regenerative potential in animal models. MEDLINE, EMBASE and LILACS databases were searched for quantitative pre‐clinical controlled animal model studies that evaluated the effect of local administration of MSC on periodontal regeneration. The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses statement guidelines. Twenty‐two studies met the inclusion criteria. Periodontal defects were surgically created in all studies. In seven studies, periodontal inflammation was experimentally induced following surgical defect creation. Differences in defect morphology were identified among the studies. Autogenous, alogenous and xenogenous MSC were used to promote periodontal regeneration. These included bone marrow‐derived MSC, periodontal ligament (PDL)‐derived MSC, dental pulp‐derived MSC, gingival margin‐derived MSC, foreskin‐derived induced pluripotent stem cells, adipose tissue‐derived MSC, cementum‐derived MSC, periapical follicular MSC and alveolar periosteal cells. Meta‐analysis was not possible due to heterogeneities in study designs. In most of the studies, local MSC implantation was not associated with adverse effects. The use of bone marrow‐derived MSC for periodontal regeneration yielded conflicting results. In contrast, PDL‐MSC consistently promoted increased PDL and cementum regeneration. Finally, the adjunct use of MSC improved the regenerative outcomes of periodontal defects treated with membranes or bone substitutes. Despite the quality level of the existing evidence, the current data indicate that the use of MSC may provide beneficial effects on periodontal regeneration. The various degrees of success of MSC in periodontal regeneration are likely to be related to the use of heterogeneous cells. Thus, future studies need to identify phenotypic profiles of highly regenerative MSC populations.