Development and characterization of waste equine bone-derived calcium phosphate cements with human alveolar bone-derived mesenchymal stem cells.

Calcium phosphate cements (CPCs) are regarded as promising graft substitutes for bone tissue engineering. However, their wide use is limited by the high cost associated with the complex synthetic processes involved in their fabrication. Cheaper xenogeneic calcium phosphate (CaP) materials derived from waste animal bone may solve this problem. Moreover, the surface topography, mechanical strength, and cellular function of CPCs are influenced by the ratio of micro- to nano-sized CaP (M/NCaP) particles. In this study, we developed waste equine bone (EB)-derived CPCs with various M/NCaP particle ratios to examine the potential capacity of EB-CPCs for bone grafting materials. Our study showed that increasing the number of NCaP particles resulted in reductions in roughness and porosity while promoting smoother surfaces of EB-CPCs. Changes in the chemical properties of EB-CPCs by NCaP particles were observed using X-ray diffractometry. The mechanical properties and cohesiveness of the EB-CPCs improved as the NCaP particle content increased. In an in vitro study, EB-CPCs with a greater proportion of MCaP particles showed higher cell adhesion. Alkaline phosphatase activity indicated that osteogenic differentiation by EB-CPCs was promoted with increased NCaP particle content. These results could provide a design criterion for bone substitutes for orthopedic disease, including periodontal bone defects.

USP1 inhibitor ML323 enhances osteogenic potential of human dental pulp stem cells.

LIM homeobox 8 (LHX8) is expressed during embryonic development of craniofacial tissues, including bone and teeth. In a previous study, the overexpression of LHX8 inhibited osteodifferentiation of human dental pulp stem cells (DPSCs). In this study, a cDNA microarray analysis was performed to reveal the molecular changes which occur in response to LHX8 overexpression in DPSCs and discover possible targets for an osteoinductive agent. There were 345 differentially expressed genes (DEGs) in response to osteoinductive signaling and 53 DEGs in response to LHX8 overexpression and osteoinductive signaling, respectively. Thirty-eight genes were common in both conditions, and among these, genes upregulated in LHX8 DPSCs but downregulated in osteodifferentiated DPSCs were chosen. Five of them had commercial inhibitors available. Among the tested inhibitors, ML323, which target DNA-binding protein inhibitor ID-1, promoted osteodifferentiation of DPSCs. In conclusion, inhibition of ID-1 led to increased osteogenesis of human DPSCs.

MSM promotes human periodontal ligament stem cells differentiation to osteoblast and bone regeneration.

Periodontal disease is the most common chronic disease of the oral and maxillofacial region, causing alveolar bone loss and ultimate loss of tooth. The purpose of treatment of periodontal disease is to promote the regeneration of periodontal tissue, including alveolar bone, and implantation of fixtures to replace the missing tooth as a result of advanced periodontal disease also requires alveolar bone regeneration. Methylsulfonylmethane (MSM) is a sulfur compound with well-known anti-inflammatory effects but its effects on bone regeneration are unknown. In this study, we investigated the effects of MSM on osteogenic differentiation of human PDLSCs (hPDLSCs) in vitro and in vivo. Our results demonstrate that MSM not only promotes the proliferation but also promotes osteogenic differentiation of hPDLSCs. MSM increased the expression levels of osteogenic specific markers that ALP, OPN, OCN, Runx2, and OSX. Smad2/3 signaling pathway was reinforced by MSM. Runx2, which downstream of Smad pathway, was expressed in accordance. Consistent with in vitro results, in vivo calvarial defect model and transplantation model revealed that MSM induces hPDLSCs to differentiate into osteoblast, which express ALP, OPN and OCN highly and enhance bone formation. These results suggest that MSM promotes osteogenic differentiation and bone formation of hPDLSCs, and Smad2/3 / Runx2 / OSX / OPN may play critical roles in the MSM-induced osteogenic differentiation. Thus, MSM combined with hPDLSCs may be a good candidate for future clinical applications in alveolar bone regeneration and can be used for graft material in reconstructive dentistry.

Extensive Surgical Procedures Result in Better Treatment Outcomes for Bisphosphonate-Related Osteonecrosis of the Jaw in Patients With Osteoporosis.

PURPOSE: To identify the risk factors associated with relapse or treatment failure after surgery for bisphosphonate-related osteonecrosis of the jaw (BRONJ) in patients with osteoporosis. PATIENTS AND METHODS: We performed a retrospective cohort study of BRONJ in patients with osteoporosis who had undergone surgical procedures from 2004 to 2016 at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. The predictor variables were a set of heterogeneous variables, including demographic (age, gender), anatomic (maxilla or mandible, or both, affected location), clinical (disease stage, etiology, comorbidities, history of intravenous bisphosphonate intake), time (conservative treatment before surgery, bisphosphonate treatment before the development of BRONJ, discontinuation of the drug before surgery, interval to final follow-up, interval to reoperation in the case of relapse or treatment failure), and perioperative variables (type of anesthesia, type of surgical procedures). The primary outcome variable was relapse after surgery that required reoperation (yes vs no). The descriptive and bivariate statistics were computed to assess the relationships between the study variables and the outcome. To determine the risk factors, we conducted a survival analysis using the Cox model. RESULTS: The final sample included 325 subjects with a median age of 75 years, and 97% were women. After surgery, 30% of patients did not completely recuperate and underwent repeat surgery. The interval from the first surgery to reoperation ranged from 10 days to 5.6 years. Relapse or treatment failure most often occurred immediately after surgery. The type of surgical procedure and mode of anesthesia were the most important factors in the treatment outcome. A drug holiday did not appear to influence the likelihood of relapse after surgery. CONCLUSIONS: Treatment of BRONJ in patients with osteoporosis might benefit from more careful and extensive surgical procedures rather than curettage performed with the patient under local anesthesia.

Simultaneous premaxillary repositioning and cheiloplasty in adult patients with unrepaired bilateral cleft lip and palate.

Primary cheiloplasty in adult patients with unrepaired complete bilateral cleft lip and palate is quite challenging due to severe premaxillary anterior projection. To get the best repair results, the author carried out repositioning of the premaxilla and repair of the lip deformity in a single stage. Positive results for the primary lip repair and appropriate repositioning of the premaxilla were achieved. No avascular necrosis of the premaxilla was observed. Repositioning of the premaxilla and repair of the lip deformity in a single operation appears to be a reliable method for treating adult patients with previously unrepaired or poorly repaired bilateral cleft lip and palate.

Integration of blue light with near-infrared irradiation accelerates the osteogenic differentiation of human dental pulp stem cells.

Blue light is used less in photobiomodulation than red or near-infrared light because of concerns about its high energy. However, some reports have suggested that blue light releases NO from nitrosated proteins, affects cell signal regulation, and promotes stem cell differentiation. Because blue and red lights could have different mechanisms of action, their combination is expected to have new consequences. In this study, human dental pulp stem cells (hDPSCs) were sequentially exposed to blue and near-infrared light to study their effects on proliferation, osteogenic differentiation, and immunomodulation. We found that NIR irradiation applied after blue light can reduce blue light toxicity improving the cell viabiltiy. Delayed luminescence and transmission electron microscopy studies showed that this combination excited hDPSCs and activated mitochondrial biogenesis. Those modulations accelerated hDPSC differentiation, as shown by an increase of about 1.3-fold in alkaline phosphatase activity in vitro and an about 1.5-fold increase in the osteocalcin-positive regions in cells implanted in nude mice compared with mice exposed to near-infrared alone.

Osseointegration of 3D-printed titanium implants with surface and structure modifications.

BACKGROUND: The purpose of this study was to establish a mechanical and histological basis for the development of biocompatible maxillofacial reconstruction implants by combining 3D-printed porous titanium structures and surface treatment. Improved osseointegration of 3D-printed titanium implants for reconstruction of maxillofacial segmental bone defect could be advantageous in not only quick osseointegration into the bone tissue but also in stabilizing the reconstruction. METHODS: Various macro-mesh titanium scaffolds were fabricated by 3D-printing. Human mesenchymal stem cells were used for cell attachment and proliferation assays. Osteogenic differentiation was confirmed by quantitative polymerase chain reaction analysis. The osseointegration rate was measured using micro computed tomography imaging and histological analysis. RESULTS: In three dimensional-printed scaffold, globular microparticle shape was observed regardless of structure or surface modification. Cell attachment and proliferation rates increased according to the internal mesh structure and surface modification. However, osteogenic differentiation in vitro and osseointegration in vivo revealed that non-mesh structure/non-surface modified scaffolds showed the most appropriate treatment effect. CONCLUSION: 3D-printed solid structure is the most suitable option for maxillofacial reconstruction. Various mesh structures reduced osteogenesis of the mesenchymal stem cells and osseointegration compared with that by the solid structure. Surface modification by microarc oxidation induced cell proliferation and increased the expression of some osteogenic genes partially; however, most of the markers revealed that the non-anodized solid scaffold was the most suitable for maxillofacial reconstruction.

Reduced graphene oxide-incorporated calcium phosphate cements with pulsed electromagnetic fields for bone regeneration.

Natural calcium phosphate cements (CPCs) derived from sintered animal bone have been investigated to treat bone defects, but their low mechanical strength remains a critical limitation. Graphene improves the mechanical properties of scaffolds and promotes higher osteoinduction. To this end, reduced graphene oxide-incorporated natural calcium phosphate cements (RGO-CPCs) are fabricated for reinforcement of CPCs' characteristics. Pulsed electromagnetic fields (PEMFs) were additionally applied to RGO-CPCs to promote osteogenic differentiation ability. The fabricated RGO-CPCs show distinct surface properties and chemical properties according to the RGO concentration. The RGO-CPCs' mechanical properties are significantly increased compared to CPCs owing to chemical bonding between RGO and CPCs. In in vitro studies using a mouse osteoblast cell line and rat-derived adipose stem cells, RGO-CPCs are not severely toxic to either cell type. Cell migration study, western blotting, immunocytochemistry, and alizarin red staining assay reveal that osteoinductivity as well as osteoconductivity of RGO-CPCs was highly increased. In in vivo study, RGO-CPCs not only promoted bone ingrowth but also enhanced osteogenic differentiation of stem cells. Application of PEMFs enhanced the osteogenic differentiation of stem cells. RGO-CPCs with PEMFs can overcome the flaws of previously developed natural CPCs and are anticipated to open the gate to clinical application for bone repair and regeneration.

Comparative study of LHX8 expression between odontoma and dental tissue-derived stem cells.

BACKGROUND: LHX8 (LIM-homeobox gene 8) is known as an important regulating factor in tooth morphogenesis. Odontoma is a mixed odontogenic tumor where epithelium and mesenchyme differentiated together, resulting in anomalous tooth structures. In this study, gene and protein expressions of LHX8 were analyzed in human odontoma-derived mesenchymal cells (HODC) compared to adult dental mesenchymal stem cells (aDSC), as well as morphological and histological characteristics of odontoma were analyzed. METHODS: aDSCs were isolated from normal teeth, and HODCs were isolated from surgically removed odontoma mass. Morphological and histological evaluations were performed to compare between compound odontomas and normal premolars. RT-PCR and real-time PCR were performed to identify LHX8 mRNA expression in the HODCs and aDSCs. LHX8 protein expression levels were observed by immunoblotting and immunofluorescent staining. RESULTS: The compound odontoma was composed of multiple tooth-like structures, which contained disorganized but recognizable enamel matrix, dentin, pulp, and cementum. LHX8 mRNA and LHX8 protein expressions were all higher in HODCs compared to those in aDSCs examined by RT-PCR, immunoblot, and immunofluorescent staining. Especially, real-time PCR showed 2.77-fold higher LHX8 expression in HODCs than in normal periodontal ligament stem cells (PDLSCs), while alveolar bone marrow stem cells (ABMSCs) expressed 0.12-fold LHX8 than PDLSCs. CONCLUSIONS: Based on these observations, LHX8 might play an important role in odontoma formation. This is the first report regarding the comparison of LHX8 expression between HODC and normal aDSCs and its overexpression in human samples. The specific mechanism of LHX8 in odontoma morphogenesis awaits further study.

Bioprinting on 3D Printed Titanium Scaffolds for Periodontal Ligament Regeneration.

The three-dimensional (3D) cell-printing technique has been identified as a new biofabrication platform because of its ability to locate living cells in pre-defined spatial locations with scaffolds and various growth factors. Osseointegrated dental implants have been regarded as very reliable and have long-term reliability. However, host defense mechanisms against infections and micro-movements have been known to be impaired around a dental implant because of the lack of a periodontal ligament. In this study, we fabricated a hybrid artificial organ with a periodontal ligament on the surface of titanium using 3D printing technology. CEMP-1, a known cementogenic factor, was enhanced in vitro. In animal experiments, when the hybrid artificial organ was transplanted to the calvarial defect model, it was observed that the amount of connective tissue increased. 3D-printed hybrid artificial organs can be used with dental implants, establishing physiological tooth functions, including the ability to react to mechanical stimuli and the ability to resist infections.

Nuclear factor I-C is essential for odontogenic cell proliferation and odontoblast differentiation during tooth root development.

Our previous studies have demonstrated that nuclear factor I-C (NFI-C) null mice developed short molar roots that contain aberrant odontoblasts and abnormal dentin formation. Based on these findings, we performed studies to elucidate the function of NFI-C in odontoblasts. Initial studies demonstrated that aberrant odontoblasts become dissociated and trapped in an osteodentin-like mineralized tissue. Abnormal odontoblasts exhibit strong bone sialoprotein expression but a decreased level of dentin sialophosphoprotein expression when compared with wild type odontoblasts. Loss of Nfic results in an increase in p-Smad2/3 expression in aberrant odontoblasts and pulp cells in the subodontoblastic layer in vivo and primary pulp cells from Nfic-deficient mice in vitro. Cell proliferation analysis of both cervical loop and ectomesenchymal cells of the Nfic-deficient mice revealed significantly decreased proliferative activity compared with wild type mice. In addition, Nfic-deficient primary pulp cells showed increased expression of p21 and p16 but decreased expression of cyclin D1 and cyclin B1, strongly suggesting cell growth arrest caused by a lack of Nfic activity. Analysis of the pulp and abnormal dentin in Nfic-deficient mice revealed an increase in apoptotic activity. Further, Nfic-deficient primary pulp cells exhibited an increase in caspase-8 and -3 activation, whereas the cleaved form of Bid was hardly detected. These results indicate that the loss of Nfic leads to the suppression of odontogenic cell proliferation and differentiation and induces apoptosis of aberrant odontoblasts during root formation, thereby contributing to the formation of short roots.

Stem cell property of postmigratory cranial neural crest cells and their utility in alveolar bone regeneration and tooth development.

The vertebrate neural crest is a multipotent cell population that gives rise to a variety of different cell types. We have discovered that postmigratory cranial neural crest cells (CNCCs) maintain mesenchymal stem cell characteristics and show potential utility for the regeneration of craniofacial structures. We are able to induce the osteogenic differentiation of postmigratory CNCCs, and this differentiation is regulated by bone morphogenetic protein (BMP) and transforming growth factor-beta signaling pathways. After transplantation into a host animal, postmigratory CNCCs form bone matrix. CNCC-formed bones are distinct from bones regenerated by bone marrow mesenchymal stem cells. In addition, CNCCs support tooth germ survival via BMP signaling in our CNCC-tooth germ cotransplantation system. Thus, we conclude that postmigratory CNCCs preserve stem cell features, contribute to craniofacial bone formation, and play a fundamental role in supporting tooth organ development. These findings reveal a novel function for postmigratory CNCCs in organ development, and demonstrate the utility of these CNCCs in regenerating craniofacial structures.

Diagnostic analysis of vertical orbital dystopia and canthal tilt for surgical correction.

OBJECTIVES: We sought to identify a clinically useful method of analyzing orbital dystopia to aid in diagnosis and treatment planning and to quantify vertical discrepancies in eye level and variations in canthal tilt in Koreans. PATIENTS AND METHODS: In 76 Korean patients with a mean age of 23.12 years, mean differences in the level of the pupils, lateral canthi, medial canthi, and canthal tilt were measured. The difference in pupil level was calculated from the perpendicular lines drawn from the midpupil area of each eye to the midline of the face to determine the amount of skeletal discrepancy of the eye. Soft tissue discrepancies were determined according to the vertical difference between the lines drawn from the lateral or medial canthus of each eye perpendicular to the midline of the face. The canthal tilt was determined from the inclination of a line connecting the lateral and medial canthi, then classified as class I, II, or III. RESULTS: Mean differences in pupil level, medial canthi, and lateral canthi were 1.57±1.10 mm, 1.14±1.07 mm, and 2.03±1.64 mm, respectively. The mean degree of canthal tilt were 8.45°±3.53° for the right side and 8.42°±3.81° for the left side. No study participants presented with class III canthal tilt. The mean canthal tilt values for those with class I tilt were 3.21°±1.68° for the right side and 3.18°±1.63° for the left side, while, for those who had class II tilt, the values were 9.60°±3.66° for the right side and 9.54°±2.99° for the left side. CONCLUSION: The presented diagnostic method of orbital dystopia can be used to effectively establish a treatment plan that takes into consideration the patient's skeletal and soft-tissue discrepancies.

Allogeneic Fibrin Clot for Odontogenic/Cementogenic Differentiation of Human Dental Mesenchymal Stem Cells.

BACKGROUND: Fetal bovine serum is widely used as a growth supplement for cell culture medium; however, animal-borne pathogens increase the risk of transmitting infectious agents. Platelet-rich fibrin is recently considered as a successful alternative but leukocytes present limits to its allogeneic feasibility. The aim of this study was to explore the effects of allogeneic fibrin clot (AFC) without leukocytes on inducing odontogenic/cementogenic differentiation of human dental pulp stem cells (hDPSCs) and human periodontal ligament stem cells (hPDLSCs) in vitro and in vivo. METHODS: AFC was prepared by high-speed centrifugation and leukocytes were almost removed, and AFC serum was obtained through three freeze-thaw cycles. hDPSCs and hPDLSCs were treated with AFC serum to investigate the odontogenic or cementogenic associated markers by real-time polymerase chain reaction. hDPSCs were treated with AFC serum and placed inside of dentin canal, hPDLSCs were treated with AFC serum to wrap outside of dentin, the mixture was then transplanted into the subcutaneous of nude mice for 12 weeks. RESULTS: AFC serum exhibited enough growth factors and cytokines to induce odontogenic/cementogenic differentiation of hDPSCs and hPDLSCs in vitro. Furthermore, AFC seurum could induce hDPSCs to differentiate into odontoblasts-like cells and pulp-like tissues, and hPDLSCs to regenerate cementum-like tissues. CONCLUSION: AFC could be an alternative safe source with growth factors for the expansion of human dental mesenchymal stem cells (hDMSCs).

Quantification of three-dimensional facial asymmetry for diagnosis and postoperative evaluation of orthognathic surgery.

BACKGROUND: To evaluate the facial asymmetry, three-dimensional computed tomography (3D-CT) has been used widely. This study proposed a method to quantify facial asymmetry based on 3D-CT. METHODS: The normal standard group consisted of twenty-five male subjects who had a balanced face and normal occlusion. Five anatomical landmarks were selected as reference points and ten anatomical landmarks were selected as measurement points to evaluate facial asymmetry. The formula of facial asymmetry index was designed by using the distances between the landmarks. The index value on a specific landmark indicated zero when the landmarks were located on the three-dimensional symmetric position. As the asymmetry of landmarks increased, the value of facial asymmetry index increased. For ten anatomical landmarks, the mean value of facial asymmetry index on each landmark was obtained in the normal standard group. Facial asymmetry index was applied to the patients who had undergone orthognathic surgery. Preoperative facial asymmetry and postoperative improvement were evaluated. RESULTS: The reference facial asymmetry index on each landmark in the normal standard group was from 1.77 to 3.38. A polygonal chart was drawn to visualize the degree of asymmetry. In three patients who had undergone orthognathic surgery, it was checked that the method of facial asymmetry index showed the preoperative facial asymmetry and the postoperative improvement well. CONCLUSIONS: The current new facial asymmetry index could efficiently quantify the degree of facial asymmetry from 3D-CT. This method could be used as an evaluation standard for facial asymmetry analysis.

Treatment of patients with clinically lymph node-negative squamous cell carcinoma of the oral cavity.

OBJECTIVE: To evaluate treatment outcome and to determine optimal treatment strategy for patients with clinically lymph node-negative (N0) oral cavity squamous cell carcinoma (SCC). METHODS: Two hundred and twenty-seven patients with oral cavity SCC received radiotherapy with curative intent. We retrospectively analyzed 69 patients with clinically N0 disease. Forty-three patients were treated with surgery followed by radiotherapy (S+EBRT) and 26 with radiotherapy alone (EBRT). The median doses administered were 63.0 Gy for S+EBRT and 70.2 Gy for EBRT. RESULTS: The rates of occult metastasis were 60% for T1, 69% for T2, 100% for T3 and 39% for T4, respectively, among patients who underwent neck dissection. A contralateral occult metastasis occurred only in two patients. The median follow-up was 39 months (range, 6-170 months). The 5-year overall survival (OS), disease-free survival (DFS), local control (LC) and regional control (RC) rates for all patients were 56, 50, 66 and 79%, respectively. The 5-year OS, DFS, LC and RC rates were 67/39% (P < 0.01), 66/24% (P < 0.01), 87/30% (P < 0.01) and 73/89% (P = 0.11) for S+EBRT/EBRT, respectively. CONCLUSIONS: The risk for occult neck metastasis is high in patients with oral cavity SCC; therefore, elective neck treatment should be considered. Excellent RC for subclinical disease can be achieved with radiotherapy alone. However, external beam radiotherapy alone to primary tumor resulted in poor LC and combined treatment with surgery and radiotherapy appeared to be a better treatment strategy.

A high concentration of MMP-2/gelatinase A and MMP-9/gelatinase B reduce NK cell-mediated cytotoxicity against an oral squamous cell carcinoma cell line.

BACKGROUND: Recent studies have shown that matrix metalloproteinases (MMPs) from tumors influence the host immune system to reduce antitumor activity. The aim of this study was to examine the influence of MMP-2 and MMP-9 on the natural killer (NK) cell. MATERIALS AND METHODS: NK cells were pretreated with either MMP-2 or MMP-9 in the experimental group but not in the control group. NK cell cytotoxicity against oral squamous cell carcinoma cells (OSCC) were examined using the [Cr51] release assay and the expression levels of surface receptors on NK cells were measured by flow cytometry. RESULTS: NK cell cytotoxicity was significantly reduced in the experimental group compared to the control group. Significant increases in KIR expression and decreases in NKG2D expression on the NK cells were observed in the experimental group. CONCLUSION: This study suggests an additional role of MMP-2 and MMP-9 in an immune escape mechanism of OSCC.

Targeted Delivery of siRNA Therapeutics using Ligand Mediated Biodegradable Polymeric Nanocarriers.

BACKGROUND: Cancer poses a major public health issue, is linked with high mortality rates across the world, and shows a strong interplay between genetic and environmental factors. To date, common therapeutics, including chemotherapy, immunotherapy, and radiotherapy, have made significant contributions to cancer treatment, although diverse obstacles for achieving the permanent "magic bullet" cure have remained. Recently, various anticancer therapeutic agents designed to overcome the limitations of these conventional cancer treatments have received considerable attention. One of these promising and novel agents is the siRNA delivery system; however, poor cellular uptake and altered siRNA stability in physiological environments have limited its use in clinical trials. Therefore, developing the ideal siRNA delivery system with low cytotoxicity, improved siRNA stability in the body's circulation, and prevention of its rapid clearance from bodily fluids, is rapidly emerging as an innovative therapeutic strategy to combat cancer. Moreover, active targeting using ligand moieties which bind to over-expressed receptors on the surface of cancer cells would enhance the therapeutic efficiency of siRNA. CONCLUSION: In this review, we provide 1) an overview of the non-viral carrier associated with siRNA delivery for cancer treatment, and 2) a description of the five major cancer-targeting ligands.

Sugar-based gene delivery systems: Current knowledge and new perspectives.

Carbohydrates, one of the most abundant natural compounds and key participants in many biological processes, are relevant in medical and industrial fields. In comparison with synthetic polymers, carbohydrates are biocompatible and have intrinsic targeting properties, enabling them to interact with cell-surface receptors. Among the different carbohydrates, polysaccharides are naturally occurring biological molecules with tremendous potential for biomedical applications. The physicochemical properties of these polysaccharide based nanoparticles, such as excellent biocompatibility, surface charge to interact with nucleic acids, low toxicity and cost effectiveness make them superior carriers for nanomedicine. In addition to variety of physicochemical properties, polysaccharides allow the great ease of chemical modification which enables the preparation of wide range of nanoparticles. In this review, we present the state-of-the-art information on the potential of polysaccharides-based polymers as non-viral gene delivery vectors in treating various diseases. Then, we discuss the chemical modification and structure/property relationship of carbohydrates.

Effects of pulsing of light on the dentinogenesis of dental pulp stem cells in vitro.

Low power light (LPL) treatment has been widely used in various clinical trials, which has been known to reduce pain and inflammation and to promote wound healing. LPL was also shown to enhance differentiation of stem cells into specific lineages. However, most studies have used high power light in mW order, and there was lack of studies about the effects of very low power light in µW. In this study, we applied 810 nm LPL of 128 µW/cm2 energy density in vitro. Upon this value, continuous wave (CW) irradiation did not induce any significant changes for differentiation of human dental pulp stem cells (hDPSCs). However, the membrane hyperpolarization, alkaline phosphatase activity, and intracellular oxidative stress were largely enhanced in the pulsed wave (PW) with 30% of duty cycle and 300-3000 Hz frequencies-LPL in which LED driver work in the form of square wave. After 21 days of daily LPL treatment, Western blot revealed the dentinogenesis in this condition in vitro. This study demonstrates that the very low power light at 810 nm enhanced significant differentiation of hDPSCs in the PW mode and there were duty cycle dependency as well as pulsing frequency dependency in the efficiency.