Mouse mandible contains distinctive mesenchymal stem cells

Although human orofacial bone-marrow-derived mesenchymal stem cells showed differentiation traits distinctly different from those of mesenchymal stem cells (MSCs) derived from long bone marrow (BMMSCs), mouse MSCs derived from orofacial bone have not been isolated due to technical difficulties, which in turn precludes the use of mouse models to study and cure orofacial diseases. In this study, we developed techniques to isolate and expand mouse orofacial bone/bone-marrow-derived MSCs (OMSCs) from mandibles and verified their MSC characteristics by single-colony formation, multi-lineage differentiation, and in vivo tissue regeneration. Activated T-lymphocytes impaired OMSCs via the Fas/Fas ligand pathway, as occurs in BMMSCs. Furthermore, we found that OMSCs are distinct from BMMSCs with respect to regulating T-lymphocyte survival and proliferation. Analysis of our data suggests that OMSCs are a unique population of MSCs and play an important role in systemic immunity.

ABBREVIATIONS

BMMSC, bone marrow mesenchymal stem cell; HA/TCP, hydroxyapatite/tricalcium phosphate; OMSC, orofacial mesenchymal stem cell; OVX, ovariectomized.

Transplantation of umbilical cord mesenchymal stem cells alleviates lupus nephritis in MRL/lpr mice

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease, which, despite the advances in immunosuppressive medical therapies, remains potentially fatal in some patients, especially in treatment-refractory patients. This study found that transplantation of umbilical cord mesenchymal stem cells (UC-MSCs) has the same therapeutic effect as transplantation of bone marrow mesenchymal stem cells (BM-MSCs), which has been reported to be efficient in treating SLE-related symptoms in MRL/lpr mice. Multi-treatment (at the 18th, 19th, and 20th weeks of age) of 1 × 10(6) UC-MSCs was able to decrease the levels of 24-h proteinuria, serum creatinine, and anti-double-stranded DNA (dsDNA) antibody, and the extent of renal injury such as crescent formation in MRL/lpr mice. A lower, but still significant, reduction in these parameters was also observed in mice receiving a single dose of UC-MSCs (at the 18th week). UC-MSCs treatment also inhibited expression of monocyte chemotactic protein-1 (MCP-1) and high-mobility group box 1 (HMGB-1) expression in a similar fashion. UC-MSCs labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE) were found in the lungs and kidneys 1 week post infusion. In addition, after 11 weeks post UC-MSCs infusion, human cells were found in kidney of UC-MSCs-treated mice. These findings indicated that UC-MSCs transplantation might be a potentially promising approach in the treatment of lupus nephritis, possibly by inhibiting MCP-1 and HMGB-1 production.

Utility of PDL progenitors for in vivo tissue regeneration: a report of 3 cases

OBJECTIVE

Periodontal disease is an inflammatory disorder with widespread morbidities involving both oral and systemic health. The primary goal of periodontal treatment is the regeneration of the lost or diseased periodontium. In this study, we retrospectively examined feasibility and safety of reconstructing the periodontal intrabony defects with autologous periodontal ligament progenitor (PDLP) implantation in three patients.

MATERIALS AND METHODS

In this retrospective pilot study, we treated 16 teeth with at least one deep intrabony defect of probing depth (PD) > OR = 6 mm with PDLP transplantation and evaluated clinical outcome measures in terms of probing depth, gingival recession and attachment gain for a duration of 32-72 months. Furthermore, we compare PDLPs with standard PDL stem cells (PDLSCs) and confirmed that PDLPs possessed progenitor characters.

RESULTS

Clinical examination indicated that transplantationof PDLPs may provide therapeutic benefit for the periodontal defects. All treated patients showed no adverse effects during the entire course of follow up. We also found that PDLPs were analogous to PDLSCs in terms of high proliferation, expression of mesenchymal surface molecules, multipotent differentiation, and in vivo tissue regain. However, PDLPs failed to express scleraxis, a marker of tendon, as seen in PDLSCs.

CONCLUSIONS

This study demonstrated clinical and experimental evidences supporting a potential efficacy and safety of utilizing autologous PDL cells in the treatment of human periodontitis.

SHED differentiate into functional odontoblasts and endothelium

Studies on mechanisms underlying the differentiation of dental pulp stem cells are critical for the understanding of the biology of odontogenesis and for dental tissue engineering. Here, we tested the hypothesis that stem cells from exfoliated deciduous teeth (SHED) differentiate into functional odontoblasts and endothelial cells. SHED were seeded in tooth slice/scaffolds and implanted subcutaneously into immunodeficient mice. SHED differentiated into functional odontoblasts that generated tubular dentin, as determined by tetracycline staining and confocal microscopy. These cells also differentiated into vascular endothelial cells, as determined by beta-galactosidase staining of LacZ-tagged SHED. In vitro, vascular endothelial growth factor (VEGF) induced SHED to express VEGFR2, CD31, and VE-Cadherin (markers of endothelium) and to organize into capillary-like sprouts. VEGF induced ERK and AKT phosphorylation (indicative of differentiation), while inhibiting phosphorylation of STAT3 (indicative of 'stemness'). Collectively, this work demonstrates that SHED can differentiate into angiogenic endothelial cells and odontoblasts capable of generating tubular dentin.

Dentin-derived BMP-2 and Odontoblast Differentiation

It is known that stem cells from exfoliated deciduous teeth (SHED) can be induced to differentiate into odontoblasts. However, the nature of dentin-derived morphogenic signals required for dental pulp stem cell differentiation remains unclear. The hypothesis underlying this work is that dentin-derived Bone Morphogenetic Proteins (BMP) are necessary for the differentiation of SHED into odontoblasts. We observed that SHED express markers of odontoblastic differentiation (DSPP, DMP-1, MEPE) when seeded in human tooth slice/scaffolds and cultured in vitro, or implanted subcutaneously into immunodeficient mice. In contrast, SHED cultured in deproteinized tooth slice/scaffolds, or scaffolds without a tooth slice, do not express these markers. SHED express the BMP receptors BMPR-IA, BMPR-IB, and BMPR-II. Notably, blockade of BMP-2 signaling inhibited the expression of markers of odontoblastic differentiation by SHED cultured in tooth slice/scaffolds. Collectively, this work demonstrates that dentin-derived BMP-2 is required to induce the differentiation of SHED into odontoblasts.

Integration of silicon nanocrystals and erbium ring cavities for a silicon pumped Er:SiO2 laser

In this work we present a novel two-stage approach to achieve electrically pumped lasing on a CMOS compatible material platform in the telecom region. The proposed design consists of an electrically pumped silicon nanocrystal (Si-nc) light source acting as an optical pump for an Erbium doped silicate (Er:SiO2) lasing cavity. The integrated design, based on concentric disks of Si-nc and Er:SiO2, provides a means of coupling the Si-nc pump signal to the Er ions without requiring overlap of the Er based lasing mode with the Si-nc material. We present an electromagnetic analysis of the pump and lasing modes in the proposed configuration. We also present fabrication and characterization of Si-nc and Er:SiO2 microdisks as components of the integrated design.

Aryl hydrocarbon nuclear translocator (hypoxia inducible factor 1beta) activity is required more during early than late tumor growth

c4 is a derivative of the mouse hepatoma cell line, Hepa-1, that harbors a mutation in the aryl hydrocarbon receptor nuclear translocator gene (Arnt, or hypoxia inducible factor 1beta [HIF-1beta]) leading to loss of activity. Clone 3 cells were generated by introducing a doxycycline-repressible Arnt expression vector into c4 cells. Clone 3 cells were injected subcutaneously into immunosuppressed mice, which were treated with doxycyline (a) throughout the growth of the subsequent tumor xenografts, or (b) from day 7 through to the end of the experiment (day 30), or not treated (c). Tumors in all groups grew exponentially between days 14 and 30, and at rates that were indistinguishable from each other. However, tumors in group a were smaller than those of the other two groups throughout the measurable growth period, while tumor volumes in groups b and c were not significantly different from each other. The degrees of vascularity and apoptosis did not correlate with the differences in degrees of growth between the different groups. Thus, Arnt is required during the early stages of growth of the tumors but less in later stages. Since Arnt does not detectably effect the growth kinetics of Hepa-1 cells either during hypoxia or normoxia, this requirement is unlikely to reflect a direct effect of Arnt on cell proliferation, and is therefore probably a consequence of altered interaction(s) between the tumor cells and the host. These studies suggest that Arnt (and HIF-1alpha/HIF-2alpha) inhibitors will be particularly effective against smaller tumors, including micrometastases.

Mesenchymal stem cells derived from dental tissues vs. those from other sources: their biology and role in regenerative medicine

To date, 5 different human dental stem/progenitor cells have been isolated and characterized: dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHED), periodontal ligament stem cells (PDLSCs), stem cells from apical papilla (SCAP), and dental follicle progenitor cells (DFPCs). These postnatal populations have mesenchymal-stem-cell-like (MSC) qualities, including the capacity for self-renewal and multilineage differentiation potential. MSCs derived from bone marrow (BMMSCs) are capable of giving rise to various lineages of cells, such as osteogenic, chondrogenic, adipogenic, myogenic, and neurogenic cells. The dental-tissue-derived stem cells are isolated from specialized tissue with potent capacities to differentiate into odontogenic cells. However, they also have the ability to give rise to other cell lineages similar to, but different in potency from, that of BMMSCs. This article will review the isolation and characterization of the properties of different dental MSC-like populations in comparison with those of other MSCs, such as BMMSCs. Important issues in stem cell biology, such as stem cell niche, homing, and immunoregulation, will also be discussed.

Eph/ephrinB Mediate Dental Pulp Stem Cell Mobilization and Function

Damage to the dentin matrix instigates the proliferation and mobilization of dental progenitor cells to the injury site, the mechanisms of which are not defined. EphB receptors and ephrin-B ligands expressed within the perivascular niche of dental pulp have been implicated following tooth injury. We propose that elevated levels of ephrin-B1 following injury may prevent the proliferation and migration of dental pulp stem cell (DPSC), while EphB/ephrin-B interaction facilitates odontoblastic differentiation. The migration, proliferation, and differentiation of DPSC in response to Eph/ephrin-B molecules was assessed in an established ex vivo tooth injury model and by in vitro assays for the assessment of colony formation and differentiation. Analysis of our data demonstrated that EphB forward signaling promoted DPSC proliferation, while inhibiting migration. Conversely, reverse signaling enhanced DPSC mineral production. These observations suggest that EphB/ephrin-B molecules are important for perivascular DPSC migration toward the dentin surfaces and differentiation into functional odontoblasts, following damage to the dentin matrix.

Lessons from the diagnosis and treatment of spontaneous vertebral arterial dissection. Case report

SUMMARY

A 36-year-old man presented a sudden left occipital headache and right limb weakness after tooth-brushing. Conventional catheter digital subtraction angiography (DSA) showed a left VA occlusion at the crotch of the posterior inferior cerebellar artery. Four days later, the patient got worse. The angiogram showed the left vertebral artery had reopened and the basilar trunk occluded above the AICA. He died two days later and autopsy demonstrated a dissection of the basilar arteries. Based on the autopsy data from the patient in this study, we suggest that the BA dissection might be due to left VA dissection, and placing a stent on the juncture between the uninjured VA and the basilar trunk might be an effective method to prevent fatal BA occlusion.

Stem cells from deciduous tooth repair mandibular defect in swine

Stem cells from human exfoliated deciduous teeth have been identified as a new post-natal stem cell population with multipotential differentiation capabilities, including regeneration of mineralized tissues in vivo. To examine the efficacy of utilizing these stem cells in regenerating orofacial bone defects, we isolated stem cells from miniature pig deciduous teeth and engrafted the critical-size bone defects generated in swine mandible models. Our results indicated that stem cells from miniature pig deciduous teeth, an autologous and easily accessible stem cell source, were able to engraft and regenerate bone to repair critical-size mandibular defects at 6 months post-surgical reconstruction. This pre-clinical study in a large-animal model, specifically swine, allows for testing of a stem cells/scaffold construct in the restoration of orofacial skeletal defects and provides rapid translation of stem-cell-based therapy in orofacial reconstruction in human clinical trials.

Inhibition of human dental pulp stem cell differentiation by Notch signaling

Notch signaling plays a critical role in development and cell fate specification. Notch receptors and ligands have been found to be expressed in dental epithelium or mesenchyme in the developing tooth, suggesting that Notch signaling may regulate odontogenesis. Post-natal human dental pulp stem cells (DPSCs) isolated from the dental pulp have characteristics of mesenchymal stem cells and can differentiate into odontoblasts. In this study, we examined whether Notch signaling regulated the odontoblastic differentiation of DPSCs. We found that over-expression of the Notch ligand, Jagged-1, activated the Notch signaling pathway in DPSCs. Jagged-1 inhibited the odontoblastic differentiation of DPSCs in vitro. Jagged-1-expressing DPSCs could not form mineralized tissues in vivo. Moreover, over-expression of the constitutively activated Notch1 intracellular domain (Notch-ICD) also inhibited odontoblastic differentiation of DPSCs. Taken together, our results demonstrate that Notch signaling can inhibit the odontoblastic differentiation of DPSCs.

The miniature pig: a useful large animal model for dental and orofacial research

Compared with small animal models such as rodents, large animal models are superior in many aspects for the study of human diseases and pre-clinical therapies. Since the development of the Minnesota miniature pig in 1949 at the Hormel Institute (USA), miniature pigs have been used as a large animal model in medical studies for scientific, economic, and ethical reasons. The oral maxillofacial region of miniature pigs is similar to that of humans in anatomy, development, physiology, pathophysiology, and disease occurrence. In this review, we describe the anatomical characteristics of the oral maxillofacial system of the miniature pig, established models of oral diseases in this animal, and other uses of the miniature pig in orofacial research.

Spatiotemporal patterns of postsynaptic density (PSD)-95 expression after rat spinal cord injury

AIMS

Postsynaptic density (PSD)-95 is a scaffolding protein linking the N-methyl-D-aspartate receptor with neuronal nitric oxide synthase (nNOS), which contributes to many physiological and pathological actions. We here investigated whether PSD-95 was involved in the secondary response following spinal cord injury (SCI).

METHODS

Spinal cord contusion (SCC) and spinal cord transection (SCT) models at thoracic (T) segment 9 (T(9)) were established in adults rats. Real-time polymerase chain reaction, Western blot, immunohistochemistry and immunofluorescence were used to detect the temporal profile and spatial distribution of PSD-95 after SCI. The association between PSD-95 and nNOS in the injured cords was also assessed by coimmmunoprecipation and double immunofluorescent staining.

RESULTS

The mRNA and protein for PSD-95 expression were significantly increased at 2 h or 8 h, and then gradually declined to the baseline level, ultimately up-regulated again from 5 days to 7 days for its mRNA level and at 7 days or 14 days for its protein level after either SCC or SCT. PSD-95 immunoreactivity was found in neurones, oligodendrocytes and synaptic puncta of spinal cord tissues within 5 mm from the lesion site. Importantly, injury-induced expression of PSD-95 was colabelled by active caspase-3 (apoptotic marker), Tau-1 (the marker for pathological oligodendrocytes) and nNOS.

CONCLUSIONS

Accompanied by the spatio-temporal changes for PSD-95 expression, the association between PSD-95 and nNOS undergoes substantial alteration after SCI. These two molecules are likely to form a complex on apoptotic neurones and pathological oligodendrocytes, which may in turn be involved in the secondary response after SCI.

Human Hertwig's epithelial root sheath cells play crucial roles in cementum formation

Hertwig's epithelial root sheath (HERS) cells are a unique population of epithelial cells in the periodontal ligament compartment. To date, their functional role has not been fully elucidated. Our hypothesis was that HERS cells may be involved in regulating differentiation of periodontal ligament stem cells (PDLSCs) and forming cementum in vivo. In this study, we found that HERS cells may be capable of promoting PDLSC differentiation and undergoing epithelial-mesenchymal transition in vitro. Immunohistochemical staining, Western blot analysis, a transwell co-culture system, and in vivo transplantation were used to characterize the interplay between HERS cells and PDLSCs, as well as the epithelial-mesenchymal transition (EMT) of HERS cells. TGFbeta1 was capable of inducing the epithelial-mesenchymal transition of HERS cells through activating the PI3K/AKT pathway. Furthermore, HERS cells were able to form cementum-like tissue when transplanted into immunocompromised mice.

ABBREVIATIONS

bone marrow mesenchymal stem cell, BMMSC; bone sialoprotein, BSP; hydroxyapatite/tricalcium phosphate, HA/TCP; Hertwig's epithelial root sheath, HERS; osteocalcin, OCN; periodontal ligament, PDL; periodontal ligament stem cell, PDLSC; phosphatidylinositol 3-kinase, PI3K.

Gene therapy for articular cartilage repair

Articular cartilage serves as the gliding surface of joints. It is susceptible to damage from trauma and from degenerative diseases. Restoration of damaged articular cartilage may be achievable through the use of cell-regulatory molecules that augment the reparative activities of the cells, inhibit the cells' degradative activities, or both. A variety of such molecules have been identified. These include insulin-like growth factor I, fibroblast growth factor 2, bone morphogenetic proteins 2, 4, and 7, and interleukin-1 receptor antagonist. It is now possible to transfer the genes encoding such molecules into articular cartilage and synovial lining cells. Although preliminary, data from in-vitro and in-vivo studies suggest that gene therapy can deliver such potentially therapeutic agents to protect existing cartilage and to build new cartilage.

Craniofacial tissue engineering by stem cells

Craniofacial tissue engineering promises the regeneration or de novo formation of dental, oral, and craniofacial structures lost to congenital anomalies, trauma, and diseases. Virtually all craniofacial structures are derivatives of mesenchymal cells. Mesenchymal stem cells are the offspring of mesenchymal cells following asymmetrical division, and reside in various craniofacial structures in the adult. Cells with characteristics of adult stem cells have been isolated from the dental pulp, the deciduous tooth, and the periodontium. Several craniofacial structures--such as the mandibular condyle, calvarial bone, cranial suture, and subcutaneous adipose tissue--have been engineered from mesenchymal stem cells, growth factor, and/or gene therapy approaches. As a departure from the reliance of current clinical practice on durable materials such as amalgam, composites, and metallic alloys, biological therapies utilize mesenchymal stem cells, delivered or internally recruited, to generate craniofacial structures in temporary scaffolding biomaterials. Craniofacial tissue engineering is likely to be realized in the foreseeable future, and represents an opportunity that dentistry cannot afford to miss.

Bone marrow-derived mesenchymal stem cells for regenerative medicine in craniofacial region

The craniofacial region contains many specified tissues including bone, cartilage, muscle, blood vessels and neurons. Defect or dysfunction of the craniofacial tissue after post-cancer ablative surgery, trauma, congenital malformations and progressive deforming skeletal diseases has a huge influence on the patient's life. Therefore, functional reconstruction of damaged tissues is highly expected. Bone marrow-derived mesenchymal stem cells (BMMSCs) are one of the most well characterized postnatal stem cell populations, and considered to be utilized for cell-based clinical therapies. Here, the current understanding and the potential applications in craniofacial tissue regeneration of BMMSCs are reviewed, and the current limitations and drawbacks are also discussed.