LMP1 regulates periodontal ligament progenitor cell proliferation and differentiation

The unexpected versatility of ALP/Enigma family proteins

One of the most intriguing features of multicellular animals is their ability to move. On a cellular level, this is accomplished by the rearrangement and reorganization of the cytoskeleton, a dynamic network of filamentous proteins which provides stability and structure in a stationary context, but also facilitates directed movement by contracting. The ALP/Enigma family proteins are a diverse group of docking proteins found in numerous cellular milieus and facilitate these processes among others. In vertebrates, they are characterized by having a PDZ domain in combination with one or three LIM domains. The family is comprised of CLP-36 (PDLIM1), Mystique (PDLIM2), ALP (PDLIM3), RIL (PDLIM4), ENH (PDLIM5), ZASP (PDLIM6), and Enigma (PDLIM7). In this review, we will outline the evolution and function of their protein domains which confers their versatility. Additionally, we highlight their role in different cellular environments, focusing specifically on recent advances in muscle research using Drosophila as a model organism. Finally, we show the relevance of this protein family to human myopathies and the development of muscle-related diseases.

LIM Mineralization Protein-1 Enhances the Committed Differentiation of Dental Pulp Stem Cells through the ERK1/2 and p38 MAPK Pathways and BMP Signaling

Tissue regeneration is the preferred treatment for dentin and bone tissue defects. Dental pulp stem cells (DPSCs) have been extensively studied for their use in tissue regeneration, including the regeneration of dentin and bone tissue. LIM mineralization protein-1 (LMP-1) is an intracellular non-secretory protein that plays a positive regulatory role in the mineralization process. In this study, an LMP-1-induced DPSCs model was used to explore the effect of LMP-1 on the proliferation and odonto/osteogenic differentiation of DPSCs, as well as the underlying mechanisms. As indicated by the cell counting kit-8 assay, the results showed that LMP-1 did not affect the proliferation of DPSCs. Overexpression of LMP-1 significantly promoted the committed differentiation of DPSCs and vice versa, as shown by alkaline phosphatase activity assay, alizarin red staining, western blot assay, quantitative real-time polymerase chain reaction assay, and in vivo mineralized tissue formation assay. Furthermore, inhibiting the activation of the extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK) pathways using specific pathway inhibitors showed that the ERK1/2 and p38 MAPK pathways attenuated the differentiation of DPSCs. Besides, the expression of BMP signaling pathway components were also determined, which suggested that LMP-1 could activate BMP-2/Smad1/5 signaling pathway. Our results not only indicated the underlying mechanism of LMP-1 treated DPSCs but also provided valuable insight into therapeutic strategies in regenerative medicine.

Differential Response of Oral Mucosal and Gingival Cells to Corynebacterium durum, Streptococcus sanguinis, and Porphyromonas gingivalis Multispecies Biofilms

Polymicrobial interactions with oral mucosal surfaces determine the health status of the host. While a homeostatic balance provides protection from oral disease, a dysbiotic polymicrobial community promotes tissue destruction and chronic oral diseases. How polymicrobial communities transition from a homeostatic to a dysbiotic state is an understudied process. Thus, we were interested to investigate this ecological transition by focusing on biofilm communities containing high abundance commensal species and low abundance pathobionts to characterize the host-microbiome interactions occurring during oral health. To this end, a multispecies biofilm model was examined using the commensal species Corynebacterium durum and Streptococcus sanguinis and the pathobiont Porphyromonas gingivalis. We compared how both single and multispecies biofilms interact with different oral mucosal and gingival cell types, including the well-studied oral keratinocyte cell lines OKF4/TERT-1and hTERT TIGKs as well as human primary periodontal ligament cells. While single species biofilms of C. durum, S. sanguinis, and P. gingivalis are all characterized by unique cytokine responses for each species, multispecies biofilms elicited a response resembling S. sanguinis single species biofilms. One notable exception is the influence of P. gingivalis upon TNF-α and Gro-α production in hTERT TIGKs cells, which was not affected by the presence of other species. This study is also the first to examine the host response to C. durum. Interestingly, C. durum yielded no notable inflammatory responses from any of the tested host cells, suggesting it functions as a true commensal species. Conversely, S. sanguinis was able to induce expression and secretion of the proinflammatory cytokines IL-6 and IL-8, demonstrating a much greater inflammatory potential, despite being health associated. Our study also demonstrates the variability of host cell responses between different cell lines, highlighting the importance of developing relevant in vitro models to study oral microbiome-host interactions.

TGF-β prevents the denervation-induced reduction of bone formation and promotes the bone regeneration through inhibiting ubiquitin-proteasome pathway

Background: Transforming growth factor beta (TGF-β) can stimulate osteogenesis as a multifunctional protein. The present study was to explore if TGF-β can prevent denervation-induced reduction of bone formation.

Materials & methods: The 6-week-old male mice were treated with recombinant human TGF-β1 (rhTGF-β1). Bone formation, endochondral bone growth rates, and gene expression of osteoblast markers were measured in the skeletal tissue by real-time PCR.

Results: RhTGF-β1 treatment prevented the denervation-induced decrease in bone formation rates, endochondral growth, and expression of Cbfa1/Runx2 (runt-related transcription factor 2), Ostecalcin (OC), and ColIA1. TGF-β1 partially inhibited the denervation-induced ubiquitination of Cbfa1/Runx2 in mouse cancellous bones via ubiquitin-proteasome pathway.

Conclusion: TGF-β prevents denervation-induced reduction of bone formation and promotes the bone regeneration through inhibiting ubiquitin-proteasome pathway at least partially.

Transgelin mediates transforming growth factor-β1-induced proliferation of human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Human periodontal ligament cells (HPDLCs) express transforming growth factor-β1 (TGF-β1) that regulates differentiation and proliferation, and plays key roles in homeostasis of PDL tissue. Transgelin is a cytoskeleton-associated protein with an Smad-binding element in its gene promoter region. In this study, we examined the localization and potential function of transgelin in PDL tissue and cells.

MATERIAL AND METHODS

Microarray analysis of HPDLC lines (2-14, 2-23 and 2-52) was performed. Expression of transgelin in HPDLCs was examined by quantitative reverse transcription-polymerase chain reaction, immunofluorescence staining and western blot analysis. Effects of TGF-β1 and its signaling inhibitor, SB431542, on transgelin expression in HPDLCs were examined by western blot analysis. The effects of transgelin knockdown by small interfering RNA (siRNA) on HPDLC proliferation stimulated by TGF-β1 were assessed by WST-1 assay.

RESULTS

In microarray and quantitative reverse transcription-polymerase chain reaction analyses, the expression levels of transgelin (TAGLN) in 2-14 and 2-23 cells, which highly expressed PDL markers such as periostin (POSTN), tissue non-specific alkaline phosphatase (ALPL), α-smooth muscle actin (ACTA2) and type I collagen A1 (COL1A1), was significantly higher than those in 2-52 cells that expressed PDL markers weakly. Immunohistochemical and immunofluorescence staining revealed expression of transgelin in rat PDL tissue and HPDLCs. In HPDLCs, TGF-β1 treatment upregulated transgelin expression, whereas inhibition of the type 1 TGF-β1 receptor by SB431542 suppressed this upregulation. Furthermore, TAGLN siRNA transfection did not promote the proliferation of HPDLCs treated with TGF-β1. The expression levels of CCNA2 and CCNE1, which regulate DNA synthesis and mitosis through the cell cycle, were also not upregulated in HPDLCs transfected with TAGLN siRNA.

CONCLUSION

Transgelin is expressed in PDL tissue and might have a role in HPDLC proliferation induced by TGF-β1 stimulation.

Phenotypic Modulation of Smooth Muscle Cells in Atherosclerosis Is Associated With Downregulation of LMOD1, SYNPO2, PDLIM7, PLN, and SYNM

OBJECTIVE

Key augmented processes in atherosclerosis have been identified, whereas less is known about downregulated pathways. Here, we applied a systems biology approach to examine suppressed molecular signatures, with the hypothesis that they may provide insight into mechanisms contributing to plaque stability.

APPROACH AND RESULTS

Muscle contraction, muscle development, and actin cytoskeleton were the most downregulated pathways (false discovery rate=6.99e-21, 1.66e-6, 2.54e-10, respectively) in microarrays from human carotid plaques (n=177) versus healthy arteries (n=15). In addition to typical smooth muscle cell (SMC) markers, these pathways also encompassed cytoskeleton-related genes previously not associated with atherosclerosis. SYNPO2, SYNM, LMOD1, PDLIM7, and PLN expression positively correlated to typical SMC markers in plaques (Pearson r>0.6, P<0.0001) and in rat intimal hyperplasia (r>0.8, P<0.0001). By immunohistochemistry, the proteins were expressed in SMCs in normal vessels, but largely absent in human plaques and intimal hyperplasia. Subcellularly, most proteins localized to the cytoskeleton in cultured SMCs and were regulated by active enhancer histone modification H3K27ac by chromatin immunoprecipitation-sequencing. Functionally, the genes were downregulated by PDGFB (platelet-derived growth factor beta) and IFNg (interferron gamma), exposure to shear flow stress, and oxLDL (oxidized low-density lipoprotein) loading. Genetic variants in PDLIM7, PLN, and SYNPO2 loci associated with progression of carotid intima-media thickness in high-risk subjects without symptoms of cardiovascular disease (n=3378). By eQTL (expression quantitative trait locus), rs11746443 also associated with PDLIM7 expression in plaques. Mechanistically, silencing of PDLIM7 in vitro led to downregulation of SMC markers and disruption of the actin cytoskeleton, decreased cell spreading, and increased proliferation.

CONCLUSIONS

We identified a panel of genes that reflect the altered phenotype of SMCs in vascular disease and could be early sensitive markers of SMC dedifferentiation.

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.

PERK-eIF2α-ATF4 pathway mediated by endoplasmic reticulum stress response is involved in osteodifferentiation of human periodontal ligament cells under cyclic mechanical force

To prevent excess accumulation of unfolded proteins in endoplasmic reticulum (ER), eukaryotic cells have signaling pathways from the ER to the cytosol or nucleus. These processes are known as the endoplasmic reticulum stress (ERS) response. Protein kinase R like endoplasmic reticulum kinase (PERK) is a major transducer of the ERS response and it directly phosphorylate α-subunit of eukaryotic initiation factor 2 (eIF2α), resulting in translational attenuation. Phosphorylated eIF2α specifically promoted the translation of the activating transcription factor 4 (ATF4). ATF4 is a known important transcription factor which plays a pivotal role in osteoblast differentiation and bone formation. Furthermore, ATF4 is a downstream target of PERK. Studies have shown that PERK-eIF2α-ATF4 signal pathway mediated by ERS was involved in osteoblastic differentiation of osteoblasts. We have known that orthodontic tooth movement is a process of periodontal ligament cells (PDLCs) osteodifferentiation and alveolar bone remodeling under mechanical force. However, the involvement of PERK-eIF2α-ATF4 signal pathway mediated by ERS in osteogenic differentiation of PDLCs under mechanical force has not been unclear. In our study, we applied the cyclic mechanical force at 10% elongation with 0.5Hz to mimic occlusal force, and explored whether PERK-eIF2α-ATF4 signaling pathway mediated by ERS involved in osteogenic differentiation of PDLCs under mechanical force. Firstly, cyclic mechanical force will induce ERS and intensify several osteoblast marker genes (ATF4, OCN, and BSP). Next, we found that PERK overexpression increased eIF2α phosphorylation and expression of ATF4, furthermore induced BSP, OCN expression, thus it will promote osteodifferentiation of hPDLCs; mechanical force could promote this effect. However, PERK(-/-) cells showed the opposite changes, which will inhibit osteodifferentiation of hPDLCs. Taken together, our study proved that PERK-eIF2α-ATF4 signaling pathway mediated by ERS involved in osteoblast differentiation of PDLCs under cyclic mechanical force.

Evolution of metastasis revealed by mutational landscapes of chemically induced skin cancers

Human tumors show a high level of genetic heterogeneity, but the processes that influence the timing and route of metastatic dissemination of the subclones are unknown. Here we have used whole-exome sequencing of 103 matched benign, malignant and metastatic skin tumors from genetically heterogeneous mice to demonstrate that most metastases disseminate synchronously from the primary tumor, supporting parallel rather than linear evolution as the predominant model of metastasis. Shared mutations between primary carcinomas and their matched metastases have the distinct A-to-T signature of the initiating carcinogen dimethylbenzanthracene, but non-shared mutations are primarily G-to-T, a signature associated with oxidative stress. The existence of carcinomas that either did or did not metastasize in the same host animal suggests that there are tumor-intrinsic factors that influence metastatic seeding. We also demonstrate the importance of germline polymorphisms in determining allele-specific mutations, and we identify somatic genetic alterations that are specifically related to initiation of carcinogenesis by Hras or Kras mutations. Mouse tumors that mimic the genetic heterogeneity of human cancers can aid our understanding of the clonal evolution of metastasis and provide a realistic model for the testing of novel therapies.

Biologic Agents for Periodontal Regeneration and Implant Site Development

The advancement of molecular mediators or biologic agents has increased tremendously during the last decade in periodontology and dental implantology. Implant site development and reconstruction of the lost periodontium represent main fields in which these molecular mediators have been employed and investigated. Different growth factors trigger different reactions in the tissues of the periodontium at various cellular levels. Proliferation, migration, and differentiation constitute the main target areas of these molecular mediators. It was the purpose of this comprehensive review to describe the origin and rationale, evidence, and the most current understanding of the following biologic agents: Recombinant Human Platelet-Derived Growth Factor-BB (rhPDGF-BB), Enamel Matrix Derivate (EMD), Platelet-Rich Plasma (PRP) and Platelet-Rich Fibrin (PRF), Recombinant Human Fibroblast Growth Factor-2 (rhFGF-2), Bone Morphogenic Proteins (BMPs, BMP-2 and BMP-7), Teriparatide PTH, and Growth Differential Factor-5 (GDF-5).

Cyclic tensile stress during physiological occlusal force enhances osteogenic differentiation of human periodontal ligament cells via ERK1/2-Elk1 MAPK pathway

Physiological occlusal force constitutively exists in the oral environment and is important for periodontal homeostasis and remodeling. Cyclic tensile stress (CTS) triggers the biological response of periodontal ligament (PDL). However, a few reports have studied the correlation between CTS during physiological occlusal force and PDL cell activities such as osteogenic differentiation. In the present study, human PDL cells (hPDLCs) were subjected to 10% elongation CTS loading at 0.5 Hz for 24 h, which represents the physiological conditions of occlusal force. Gene expression microarray was used to investigate the mechano-induced differential gene profile and pathway analysis in vitro. The osteogenic relative factors, that is, SPP1, RUNX2, and SP7, were assessed by real-time PCR and Western blot. The involvement of mitogen-activated protein kinase (MAPK) signaling pathways was investigated by Western blot with a specific inhibitor. The expressions of SPP1, RUNX2, SP7, p-ERK1/2, and p-Elk1 were up-regulated after 10% CTS exposure. However, these up-regulated expressions were prevented by ERK1/2 inhibitor U0126 in the physiological occlusal force-applied hPDLCs. These results showed that 10% CTS could enhance osteogenic differentiation of hPDLCs via ERK1/2-Elk1 MAPK pathway, indicating that CTS during physiological occlusal force is a potent agent for PDL remodeling.

Modulation of osteoblastic/odontoblastic differentiation of adult mesenchymal stem cells through gene introduction: a brief review

Bone tissue engineering is one of the important therapeutic approaches to the regeneration of bones in the entire field of regeneration medicine. Mesenchymal stem cells (MSCs) are actively discussed as material for bone tissue engineering due to their ability to differentiate into autologous bone. MSCs are able to differentiate into different lineages: osteo/odontogenic, adipogenic, and neurogenic. The tissue of origin for MSCs defines them as bone marrow-derived stem cells, adipose tissue-derived stem cells, and, among many others, dental stem cells. According to the tissue of origin, DSCs are further stratified into dental pulp stem cells, periodontal ligament stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, and dental papilla cells. There are numerous in vitro/in vivo reports suggesting successful mineralization potential or osteo/odontogenic ability of MSCs. Still, there is further need for the optimization of MSCs-based tissue engineering methods, and the introduction of genes related to osteo/odontogenic differentiation into MSCs might aid in the process. In this review, articles that reported enhanced osteo/odontogenic differentiation with gene introduction into MSCs will be discussed to provide a background for successful bone tissue engineering using MSCs with artificially introduced genes.

Lim mineralization protein is involved in the premature calvarial ossification in sporadic craniosynostoses

Sporadic mono-sutural craniosynostosis represents a highly prevalent regional bone disorder, where a single cranial suture undergoes premature ossification due to a generally unclear etiopathogenesis. The LIM mineralization protein (LMP) was recently described as an efficient osteogenic molecule involved in osteoblast differentiation, expressed in calvarial tissues upon corticosteroid-osteogenic induction and used as a potent inducer of bone formation in several animal models. In this study, calvarial cells isolated from both prematurely fused and physiologically patent sutures of children with sporadic craniosynostosis, were used as an in vitro paradigmatic model for the study of the molecular events involved in calvarial osteogenesis, focusing on the possible role of the LMP-related osteogenic signaling. Calvarial cells isolated from both patent and fused sutures expressed a mesenchymal-like immunophenotype. Cells isolated from fused sutures displayed an increased osteogenic potential, being able to undergo spontaneous mineralization and premature response to osteogenic induction, leading to in vitro bone nodule formation. The expression of LMP and its target genes (bone morphogenetic protein-2, osteocalcin and Runt-related transcription factor 2) was significantly up-regulated in cells derived from the fused sutures. Upon silencing the expression of LMP in fused suture-derived cells, the osteogenic potential along with the expression of osteo-specific transcription factors decreased, restoring the "physiologic" cell behavior. These results suggested that: 1. mesenchymal cells residing in fused sutures display a constitutionally active osteogenic disposition leading to the premature suture ossification; 2. the molecular basis of the overactive osteogenic process may at least in part involve a deregulation of the LMP-related pathway in calvarial cells.

Prospective potency of TGF-β1 on maintenance and regeneration of periodontal tissue

Periodontal ligament (PDL) tissue, central in the periodontium, plays crucial roles in sustaining tooth in the bone socket. Irreparable damages of this tissue provoke tooth loss, causing a decreased quality of life. The question arises as to how PDL tissue is maintained or how the lost PDL tissue can be regenerated. Stem cells included in PDL tissue (PDLSCs) are widely accepted to have the potential to maintain or regenerate the periodontium, but PDLSCs are very few in number. In recent studies, undifferentiated clonal human PDL cell lines were developed to elucidate the applicable potentials of PDLSCs for the periodontal regenerative medicine based on cell-based tissue engineering. In addition, it has been suggested that transforming growth factor-beta 1 is an eligible factor for the maintenance and regeneration of PDL tissue.

Lim mineralization protein 3 induces the osteogenic differentiation of human amniotic fluid stromal cells through Kruppel-like factor-4 downregulation and further bone-specific gene expression

Multipotent mesenchymal stem cells with extensive self-renewal properties can be easily isolated and rapidly expanded in culture from small volumes of amniotic fluid. These cells, namely, amniotic fluid-stromal cells (AFSCs), can be regarded as an attractive source for tissue engineering purposes, being phenotypically and genetically stable, plus overcoming all the safety and ethical issues related to the use of embryonic/fetal cells. LMP3 is a novel osteoinductive molecule acting upstream to the main osteogenic pathways. This study is aimed at delineating the basic molecular events underlying LMP3-induced osteogenesis, using AFSCs as a cellular model to focus on the molecular features underlying the multipotency/differentiation switch. For this purpose, AFSCs were isolated and characterized in vitro and transfected with a defective adenoviral vector expressing the human LMP3. LMP3 induced the successful osteogenic differentiation of AFSC by inducing the expression of osteogenic markers and osteospecific transcription factors. Moreover, LMP3 induced an early repression of the kruppel-like factor-4, implicated in MSC stemness maintenance. KLF4 repression was released upon LMP3 silencing, indicating that this event could be reasonably considered among the basic molecular events that govern the proliferation/differentiation switch during LMP3-induced osteogenic differentiation of AFSC.

Quantitative determination of matrix Gla protein (MGP) and BMP-2 during the osteogenic differentiation of human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Matrix Gla protein (MGP) has been recognized as a potent calcification inhibitor and a regulator for bone morphogenetic protein-2 (BMP-2). The periodontal ligament (PDL) is a non-mineralized connective tissue located between two mineralized tissues, the cementum and the alveolar bone. However, the mechanism by which PDL prevents mineralization has yet to be defined. This study aims to examine the expression pattern of MGP and BMP-2 during human periodontal ligament cells (hPDLCs) osteogenic differentiation in vitro, preliminarily exploring their roles in this process.

MATERIALS AND METHODS

hPDLCs were obtained and cultured in mineralizing medium. The expression of MGP and BMP-2 was confirmed by RT-PCR and immunofluorescence staining. In the process of osteogenic induction, alkaline phosphatase (ALP) activity, extracelluar calcium deposition, and mineralized nodules were measured. Quantitative real-time RT-PCR was performed to evaluate mRNA expression of MGP, BMP-2 and osteogenic marker genes, including ALP, bone sialoprotein (BSP), type I collagen (COLI), osteocalcin (OCN), and runt-related transcription factor 2 (Runx2). The protein expression of MGP and BMP-2 was analyzed by western blotting.

RESULTS

Co-localization of MGP and BMP-2 was visualized in hPDLCs. After osteogenic induction, ALP activity, calcium deposition, mineralized nodules, and osteogenic marker genes were significantly up-regulated. mRNA expression of MGP and BMP-2 generally decreased, although MGP mRNA increased on day 14 and 21 compared with the control, and protein expression of MGP and BMP-2 was down-regulated.

CONCLUSION

Our results indicate that MGP might regulate hPDLCs osteogenic differentiation which might keep a potential relationship with BMP-2 in this process.

LIM domain protein-3 (LMP3) cooperates with BMP7 to promote tissue regeneration by ligament progenitor cells

Gene transfer of key regulators of osteogenesis for mesenchymal stem cells represents a promising strategy to regenerate bone. It has been reported that LMP3, a transcription variant of LIM domain mineralization protein (LMP) lacking LIM domains, can induce osteogenesis in vitro and in vivo. As little is known about the effects of LMP3 gene therapy on periodontal ligament (PDL) cell osteogenic differentiation, this study sought to explore whether gene delivery of LMP3 can promote PDL cell mineralization and bone formation. Our results showed that adenoviral mediated gene transfer of LMP3 (AdLMP3) significantly upregulated ALP (Alkaline Phosphatase), BSP (Bone Sialoprotein) and BMP2 gene expression and increased in vitro matrix mineralization in human PDL. Although AdLMP3 gene delivery to PDL cells did not induce ectopic bone formation in vivo, we found that AdLMP3 augments new bone formation, which co-delivered with AdBMP7 gene transfer. Our study provides the evidence that there is a synergistic effect between LMP3 and BMP-7 in vivo, suggesting that LMP3 delivery may be used to augment BMP-mediated osteogenesis. LMP3 and BMP-7 combinatory gene therapy may also have specific applications for oral and periodontal regenerative medicine.

Sonic hedgehog stimulates proliferation of human periodontal ligament stem cells

Regulation of cell renewal in the periodontium is a critical cell function that has not been clarified. Sonic hedgehog (Shh) is a secreted signaling molecule that plays a key role during development and adult tissue homeostasis. In the present study, we have analyzed the role played by Shh in human periodontal ligament stem cell (HPLSC) proliferation. HPLSC were isolated with anti-STRO-1 antibodies. Shh increased the expression of GLI1 and PTC-1 and selectively stimulated cell proliferation in STRO-1(+) derived from adult periodontal ligament. Shh components were localized to primary cilia in STRO-1(+) cells after Shh stimulation. STRO-1(+) also expressed Shh, suggesting an autocrine-regulated phenomenon. Thus, we propose that Shh plays a critical role in the regulation of cell proliferation in STRO-1(+)/HPLSC.

Cell- and gene-based therapeutic strategies for periodontal regenerative medicine

Inflammatory periodontal diseases are a leading cause of tooth loss and are linked to multiple systemic conditions, such as cardiovascular disease and stroke. Reconstruction of the support and function of affected tooth-supporting tissues represents an important therapeutic endpoint for periodontal regenerative medicine. An improved understanding of periodontal biology coupled with current advances in scaffolding matrices has introduced novel treatments that use cell and gene therapy to enhance periodontal tissue reconstruction and its biomechanical integration. Cell and gene delivery technologies have the potential to overcome limitations associated with existing periodontal therapies, and may provide a new direction in sustainable inflammation control and more predictable tissue regeneration of supporting alveolar bone, periodontal ligament, and cementum. This review provides clinicians with the current status of these early-stage and emerging cell- and gene-based therapeutics in periodontal regenerative medicine, and introduces their future application in clinical periodontal treatment. The paper concludes with prospects on the application of cell and gene tissue engineering technologies for reconstructive periodontology.