Isolation, identification and osteogenic capability analysis of mesenchymal stem cells derived from different layers of human maxillary sinus membrane.

AIM: To discover the populations of mesenchymal stem cells (MSCs) derived from different layers of human maxillary sinus membrane (hMSM) and evaluate their osteogenic capability. MATERIALS AND METHODS: hMSM was isolated into a monolayer using the combined method of physical separation and enzymatic digestion. The localization of MSCs in hMSM was performed by immunohistological staining and other techniques. Lamina propria layer-derived MSCs (LMSCs) and periosteum layer-derived MSCs (PMSCs) from hMSM were expanded using the explant cell culture method and identified by multilineage differentiation assays, colony formation assay, flow cytometry and so on. The biological characteristics of LMSCs and PMSCs were compared using RNA sequencing, reverse transcription and quantitative polymerase chain reaction, immunofluorescence staining, transwell assay, western blotting and so forth. RESULTS: LMSCs and PMSCs from hMSMs were both CD73-, CD90- and CD105-positive, and CD34-, CD45- and HLA-DR-negative. LMSCs and PMSCs were identified as CD171+/CD90+ and CD171-/CD90+, respectively. LMSCs displayed stronger proliferation capability than PMSCs, and PMSCs presented stronger osteogenic differentiation capability than LMSCs. Moreover, PMSCs could recruit and promote osteogenic differentiation of LMSCs. CONCLUSIONS: This study identified and isolated two different types of MSCs from hMSMs. Both MSCs served as good potential candidates for bone regeneration.

Hsa_circRNA_33287 promotes the osteogenic differentiation of maxillary sinus membrane stem cells via miR-214-3p/Runx3.

BACKGROUND: Circular RNAs (circRNAs) comprise a novel class of noncoding RNAs that play important roles in a variety of diseases. However, the mechanism by which circRNAs regulate the osteogenic differentiation of maxillary sinus membrane stem cells (MSMSCs) remains largely unclear. METHODS: Microarray analysis was used to explore the expression profiles of circRNAs during the osteogenic differentiation of normal and BMP2 induced-MSMSCs. CircRNA_33287 was identified by agarose electrophoresis, quantitative real-time PCR (qRT-PCR), and western blotting. The function of circRNA_33287 was assessed by loss- and gain-of-function techniques and Alizarin red staining. Potential miRNA binding sites for circRNA_33287, and the target genes of miR-214-3p, were predicted by using online bioinformatics analysis tools. The relationships among the regulatory roles played by circRNA_33287, miR-214-3p, and Runt-related transcription factor 3 (Runx3), during the osteogenic differentiation of MSMSCs were verified by use of the dual luciferase reporter assay, qRT-PCR, and western blotting techniques, respectively. In addition, the molecular sponge potential of circRNA_33287 for miRNA was assessed via in vivo ectopic bone formation and a histological analysis performed after hematoxylin and eosin staining. RESULTS: Expression of circRNA_33287 was confirmed to be up-regulated during the osteogenic differentiation of MSMSCS. Overexpression and silencing of circRNA_33287 increased and decreased the expression levels of key markers of osteogenesis, respectively, including Runx2, OSX, and ALP. Furthermore, circRNA_33287 acted as a molecular sponge for miR-214-3p, which regulated Runx3 expression by targeting its 3'UTR. Moreover, circRNA_33287 protected Runx3 from miR-214-3p-mediated suppression. In addition, circRNA_33287 was shown to increase ectopic bone formation in vivo and displayed the strongest ability to stimulate bone formation when co-transfected with a miR-214-3p inhibitor. CONCLUSION: The novel pathway circRNA_33287/miR-214-3p/Runx3 was found to play a role in regulating the osteoblastic differentiation of MSMSCs in the posterior maxilla.

Bisphosphonates hinder osteoblastic/osteoclastic differentiation in the maxillary sinus mucosa-derived stem cells.

OBJECTIVES: Although bisphosphonates (BPs) are known to be associated with osteonecrosis of the maxilla, the precise effects of BPs on bone metabolism in human maxillary sinus mucosal cells (HMSMCs) are not yet known. The purposes of this study were to examine the effects of the BPs zoledronate (ZOL) and alendronate (ALN) on osteoblastic and osteoclastic differentiation in HMSMCs and to investigate the signaling pathways involved. MATERIALS AND METHODS: The effects of ZOL and ALN were assessed for osteoblast differentiation by alkaline phosphatase (ALP) activity, alizarin red staining, and RT-PCR for genes encoding Runx2 and osterix. Receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclast differentiation in bone marrow macrophages (BMMs) was also examined. RESULTS: ZOL and ALN both suppressed osteoblastic differentiation, as evidenced by their effects on ALP activity, mineralization nodule formation, and the mRNA expression levels of osteoblastic transcript factors. The RANKL/osteoprotegerin ratio in HMSMCs was increased by ALN, whereas ZOL had the opposite effect. Conditioned medium obtained from ALN-treated HMSMCs stimulated osteoclast formation and upregulated NFATc1 expression, whereas conditioned medium from ZOL-treated cells did not. ALN was more cytotoxic and stimulated apoptosis more strongly than ZOL. BPs decreased the protein levels of the non-canonical Wnt signaling protein Wnt5a and calmodulin-dependent kinase II. Moreover, recombinant human Wnt5a reversed the effects of BPs on osteoblastic and osteoclastic differentiation. CONCLUSION: This study is the first demonstration that BPs exert negative effects on osteoblastic and osteoclastic processes via the non-canonical Wnt pathway in HMSMSCs. CLINICAL RELEVANCE: It suggests that patients taking BPs during the period of maxillary sinus lifting and amentation should be given special attention.

Lnc-NTF3-5 promotes osteogenic differentiation of maxillary sinus membrane stem cells via sponging miR-93-3p.

BACKGROUND: The function and the mechanism of long non-coding RNAs (lncRNAs) on the osteogenic differentiation of maxillary sinus membrane stem cells (MSMSCs) remain largely unknown. MATERIALS AND METHODS: The expression of lnc-NTF3-5 and Runt-related transcription factor 2 (RUNX2), Osterix (OSX), and Alkaline Phosphatase (ALP) was examined by quantitative real-time PCR (qRT-PCR) in MSMSCs during the process osteogenic differentiation. Then the function of lnc-NTF3-5 was evaluated by loss- and gain-of-function techniques, as well as qRT-PCR, western blot, and Alizarin Red staining. In addition, the microRNAs (miRNAs) sponge potential of lnc-NTF3-5 was assessed through RNA immunoprecipitation, dual luciferase reporter assay, and in vivo ectopic bone formation. RESULTS: Lnc-NTF3-5, RUNX2, OSX, and ALP increased alone with the differentiation. Inhibition of lnc-NTF3-5 decreased the expression of RUNX2, OSX, and ALP both at mRNA and protein levels. Alizarin red staining showed similar trend. In contrast, overexpression of lnc-NTF3-5 presented totally opposite effects. Besides, overexpression of lnc-NTF3-5 could decrease the expression of microRNA-93-3p (miR-93-3p). Enhance miR-93-3p could also inhibit the expression level of lnc-NTF3-5. RNA immunoprecipitation demonstrated that lnc-NTF3-5 is directly bound to miR-93-3p and dual luciferase reporter assay proved that miR-93-3p targets 3' UTR of RUNX2 to regulate its expression. Ultimately, in vivo bone formation study showed that lnc-NTF3-5 and miR-93-3p inhibitor co-transfection group displayed the strongest bone formation. CONCLUSIONS: The novel pathway lnc-NTF3-5/miR-93-3p/RUNX2 could regulate osteogenic differentiation of MSMSCs and might serve as a therapeutic target for bone regeneration in the posterior maxilla.

miR-27b-3p Suppressed Osteogenic Differentiation of Maxillary Sinus Membrane Stem Cells by Targeting Sp7.

OBJECTIVE: To explore the critical role and function of miRNAs in the regulation of development and physiology of maxillary sinus membrane stem cell (MSMSC) osteogenesis. METHODS: Microarray analysis was performed to screen the miRNAs expression profiles during the process of MSMSC osteogenic differentiation. Quantitative real-time polymerase chain reaction was applied to verify the miRNAs expression profiles. Gain- and loss-of-function experiments were used to demonstrate that miR-27b-3p inhibited MSMSC osteoblastic differentiation. Bioinformatic analysis was performed to predict the potential target of miR-27b-3p and then demonstrated by luciferase reporter assay and western blot. The negative regulation between miR-27b-3p and Sp7 was further confirmed using mimic and inhibitor of miR-27b-3p in vitro. Xenograft mice model was generated to confirm the relationship between miR-27b-3p and Sp7 using recombinant adenoviruses in vivo. RESULTS: MiR-27b-3p was downregulated during osteogenic differentiation of MSMSCs. The expression of Sp7, alkaline phosphatase, and osteocalcin decreased when transfected with miR-27b-3p-mimic in MSMSCs after osteogenic differentiation. MiR-27b-3p directly targeted Sp7 and inhibited the MSMSC osteogenesis in vivo. CONCLUSION: MiR-27b-3p suppressed the osteogenic differentiation of MSMSCs by directly inhibiting Sp7.

miR-1827 inhibits osteogenic differentiation by targeting IGF1 in MSMSCs.

We recently reported that maxillary sinus membrane stem cells (MSMSCs) have osteogenic potential. However, the biological mechanisms of bone formation remain unclear. In this study, we investigated the role and mechanisms of microRNAs (miRNAs) in the osteogenic differentiation of MSMSCs. The expression of miRNAs was determined in differentiated MSMSCs by comprehensive miRNA microarray analysis and quantitative RT-PCR (qRT-PCR). We selected miR-1827 for functional follow-up studies to explore its significance in MSMSCs. Here, miR-1827 was found to be up-regulated during osteogenic differentiation of MSMSCs. Over expression of miR-1827 inhibited osteogenic differentiation of MSMSCs in vitro, whereas the repression of miR-1827 greatly promoted cell differentiation. Further experiments confirmed that insulin-like growth factor 1 (IGF1) is a direct target of miR-1827. miR-1827 inhibited osteogenic differentiation partially via IGF1, which in turn is a positive regulator of osteogenic differentiation. Moreover, miR-1827 suppressed ectopic bone formation and silencing of miR-1827 led to increased bone formation in vivo. In summary, this study is the first to demonstrate that miR-1827 can regulate osteogenic differentiation. The increase in miR-1827 expression observed during osteogenesis is likely a negative feedback mechanism, thus offering a potential therapeutic target to address inadequate bone volume for dental implantation through inhibiting miR-1827.

Long Noncoding RNA Sponges miR-454 to Promote Osteogenic Differentiation in Maxillary Sinus Membrane Stem Cells.

OBJECTIVE: Although increasing evidence has shown that long noncoding RNAs (lncRNAs) play an important regulatory role in pluripotency and differentiation of mesenchymal stem cells, little is known about the role of lncRNA in maxillary sinus membrane stem cells (MSMSCs). The goal of this study was to investigate the expression profile and function of lncRNAs on osteogenic differentiation of MSMSCs. MATERIALS AND METHODS: By using lncRNA microarray, we identify a novel osteogenesis differentiation-related lncRNA of MSMSCs (lncRNA-MODR). The functional role of lncRNA-MODR in regulating osteogenesis was evaluated by quantitative real-time polymerase chain reaction, western blot, and alizarin red staining. Bioinformatic analyses of the predicted target genes (gene ontology, pathway, and network analysis) were applied for further study of lncRNA-MODR. RESULTS: We show that lncRNA-MODR is gradually upregulated during osteogenic differentiation. lncRNA-MODR overexpression upregulated, whereas lncRNA-MODR silencing decreased the expression of the osteogenic key marker, runt-related transcription factor 2 (RUNX2). In-depth analyses showed that lncRNA-MODR acts as a molecular sponge for microRNA-454 (miR-454) and that prevents RUNX2 from mi-454-mediated suppression. CONCLUSION: The lncRNAs act as a competing endogenous RNA to sequester microRNA-454 (miR-454), leading to heightened RUNX2 expression and thus promotes osteogenesis of MSMSCs.

Mesenchymal stem cells with osteogenic potential in human maxillary sinus membrane: an in vitro study.

OBJECTIVES: The aim of our study is to prove and validate the existence of an osteogenic progenitor cell population within the human maxillary Schneiderian sinus membrane (hMSSM) and to demonstrate their potential for bone formation. MATERIALS AND METHODS: Ten hMSSM samples of approximately 2 × 2 cm were obtained during a surgical nasal approach for treatment of chronic rhinosinusitis and were retained for this study. The derived cells were isolated, cultured, and assayed at passage 3 for their osteogenic potential using the expression of Alkaline phosphatase, alizarin red and Von Kossa staining, flow cytometry, and quantitative real-time polymerase chain reaction. RESULTS: hMSSM-derived cells were isolated, showed homogenous spindle-shaped fibroblast-like morphology, characteristic of mesenchymal progenitor cells (MPCs), and demonstrated very high expression of MPC markers such as STRO-1, CD44, CD90, CD105, and CD73 in all tested passages. In addition, von Kossa and Alizarin red staining showed significant mineralization, a typical feature of osteoblasts. Moreover, alkaline phosphatase (ALP) activity was significantly increased at days 7, 14, 21, and 28 of culture in hMSSM-derived cells grown in osteogenic medium, in comparison to controls. Furthermore, osteogenic differentiation significantly upregulated the transcriptional expression of osteogenic markers such as ALP, Runt-related transcription factor 2 (Runx-2), bone morphogenetic protein (BMP)-2, osteocalcin (OCN), osteonectin (ON), and osteopontin (OPN), confirming that hMSSM-derived cells are of osteoprogenitor origin. Finally, hMSSM-derived cells were also capable of producing OPN proteins upon culturing in an osteogenic medium. CONCLUSION: Our data showed that hMSSM holds mesenchymal osteoprogenitor cells capable of differentiating to the osteogenic lineage. CLINICAL RELEVANCE: hMSSM contains potentially multipotent postnatal stem cells providing a promising clinical application in preimplant and implant therapy.

Differences in urinary leukotriene E4 levels and distribution of eosinophils between chronic rhinosinusitis patients with aspirin-intolerant and -tolerant asthma.

OBJECTIVE: Urinary leukotriene E4 (U-LTE4) concentrations are significantly elevated in patients with aspirin-intolerant asthma (AIA). However, the relationship between the clinicopathogenetic features of eosinophilic rhinosinusitis and U-LTE4 concentration remains unknown. Here we examined the relationship between U-LTE4 level and eosinophil in chronic rhinosinusitis. METHODS: We measured the U-LTE4 concentrations and eosinophil counts in ethmoidal and maxillary sinuses and peripheral blood in 30 asthmatic patients (including 15 AIA patients). RESULTS: Eosinophil counts in ethmoidal sinuses and peripheral blood were markedly higher in asthmatic patients than in controls. Although there were no significant differences between eosinophil counts in maxillary and ethmoidal sinuses for ATA group, eosinophil counts were higher in ethmoidal sinus compared to that in maxillary sinus in the AIA group (P<.05). Eosinophil counts were higher in the maxillary than in ethmoidal sinuses for control patients (P<.05). Despite low correlation between eosinophil counts in peripheral blood and eosinophil counts in maxillary sinus (rs=0.4323, P<.001), moderate correlation was observed between eosinophil counts in peripheral blood and eosinophil counts in ethmoidal sinus (rs=0.5249, P<.0001). Basal U-LTE4 concentrations were higher in AIA patients than in those with aspirin-tolerant asthma. Despite low correlation between eosinophil counts and U-LTE4 concentration in maxillary sinus (rs=0.3849, P<.01), moderate correlation was observed between eosinophil counts and U-LTE4 concentrations in ethmoidal sinus (rs=0.4736, P<.001). CONCLUSION: We describe the differences in U-LTE4 and other parameters in AIA compared to ATA, and correlation among parameters. We demonstrate that eosinophil-dominant inflammation starts in ethmoidal sinus clinicopathogenetically in CRS with asthma. U-LTE4 concentration was not exclusively associated with eosinophil counts in ethmoidal sinus. Eosinophils in ethmoidal sinus may be a major production site for CysLTs, particularly in AIA. CRS with AIA is assumed to be characterized by leukotriene-eosinophil cross-interaction in ethmoidal sinus.

Significance of the Immunohistochemical Expression of Bone Morphogenetic Protein-4 in Bone Maturation after Maxillary Sinus Grafting in Humans.

BACKGROUND: Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-ß (TGFß) protein superfamily and are known to be involved in bone and cartilage formation. Within this family, BMP-4 is one of the most studied members. It has been shown to induce osteogenic differentiation of osteoblasts and osteoprogenitor cells in vitro, but the intimate processes in which this protein promotes and regulates osseous repair still remains unclear. PURPOSE: To assess whether the native cellular immunohistochemical expression of BMP-4 correlates with the maturation of bone samples obtained at 6 months after maxillary sinus augmentation. MATERIALS AND METHODS: Histopathological and histomorphometrical analyses were performed in all the samples, which were obtained from a total of 58 patients. Immunohistochemical expression of BMP-4 was analyzed in 30 core biopsies obtained from maxillary sinuses grafted with a combination of anorganic bovine bone and autogenous cortical bone [1:1] (AB-group), and 18 biopsies from maxillary sinuses grafted solely with a cortico-cancellous particulate allograft (M-group), all of them after a 6-month healing period. Also, 10 biopsies of native pristine bone were obtained and used as control group (C-group). RESULTS: Mild to moderate immunohistochemical expression of native granular BMP-4 was present in 56.8% (31.0% AB-group, 22.4% M-group, and 3.4% C-group) (p = 0.000, chi-square) of the specimens analyzed. BMP-4 expression was primarily located in the cytoplasm of osteoblasts, osteoclasts, and epithelial cells of the schneiderian membrane. Whereas significant differences were observed in the proportion of mineralized tissue and cellularity between sinuses grafted with anorganic bovine bone, allograft, or nongrafted sinuses, there were no statistically significant differences in the cellular expression of BMP-4 among groups. CONCLUSION: Our findings suggest that the native expression of BMP-4 appears to be associated with normal bone homeostasis and reparation in grafted and nongrafted maxillary sites.

Histological and Histomorphometric Human Results of HA-Beta-TCP 30/70 Compared to Three Different Biomaterials in Maxillary Sinus Augmentation at 6 Months: A Preliminary Report.

OBJECTIVE: The aim of this investigation was to examine the bone regenerative potential of newly biphasic calcium phosphate ceramics (HA-ß-TCP 30/70), by assessing histological and histomorphometric results of human specimens retrieved from sinuses augmented with HA-ß-TCP 30/70, and comparing them to anorganic bovine bone (ABB), mineralized solvent-dehydrated bone allograft (MSDBA), and equine bone (EB), after a healing period of 6 months. MATERIALS AND METHODS: Four consecutive patients with edentulous atrophic posterior maxilla were included in this report. A two-stage procedure was carried out for sinus augmentation with HA-ß-TCP 30/70, ABB, MSDBA, and EB. After 6 months, specimens were retrieved at the time of implant placement and processed for histological and histomorphometric analyses. RESULTS: At histological examination, all biomaterials were in close contact with the newly formed bone and showed the same pattern of bone formation; the grafted granules were surrounded by a bridge-like network of newly formed bone. A limited number of ABB particles were partially covered by connective tissue. The histomorphometric analysis revealed 30.2% newly formed bone for Ha-ß-TCP 30/70, 20.1% for ABB, 16.4% for MSDBA, and 21.9% for EB. CONCLUSIONS: Within the limitations of the present investigation, these results support the successful use of HA-ß-TCP 30/70 for sinus augmentation.

Investigation of multipotent postnatal stem cells from human maxillary sinus membrane.

Maxillary sinus membrane (MSM) elevation is a common surgical technique for increasing bone height in the posterior maxilla prior to dental implant placement. However, the biological nature of bone regeneration in MSM remains largely unidentified. In this study, MSM tissue was obtained from 16 individuals during orthognathic surgery and used to isolate MSM stem cells (MSMSCs) by single-colony selection and STRO-1 cell sorting. The cell characteristics in terms of colony-forming ability, cell surface antigens, multi-differentiation potential and in vivo implantation were all evaluated. It was found that MSMSCs were of mesenchymal origin and positive for mesenchymal stem cell (MSC) markers such as STRO-1, CD146, CD29 and CD44; furthermore, under defined culture conditions, MSMSCs were able to form mineral deposits and differentiate into adipocytes and chondrocytes. When transplanted into immunocompromised rodents, MSMSCs showed the capacity to generate bone-like tissue and, importantly, maintain their MSC characteristics after in vivo implantation. These findings provide cellular and molecular evidence that MSM contains stem cells that show functional potential in bone regeneration for dental implant.

Autogenous bone combined with anorganic bovine bone for maxillary sinus augmentation: analysis of the osteogenic potential of cells derived from the donor and the grafted sites.

OBJECTIVES: This study aimed to comparatively evaluate the in vitro osteogenic potential of cells obtained from the mandibular ramus (MR, autogenous bone donor site) and from the maxillary sinus (MS) bone grafted with a mixture of anorganic bovine bone (ABB) and MR prior to titanium implant placement (MS, grafted implant site). MATERIAL AND METHODS: Cells were obtained from three patients subjected to MS floor augmentation with a 1 : 1 mixture of ABB (GenOx Inorg(®) ) and MR. At the time of the sinus lift procedure and after 8 months, prior to implant placement, bone fragments were taken from MR and MS, respectively, and subjected to trypsin-collagenase digestion for primary cell culturing. Subcultured cells were grown under osteogenic condition for up to 21 days and assayed for proliferation/viability, osteoblast marker mRNA levels, alkaline phosphatase (ALP) activity and calcium content/Alizarin red staining. ALP activity was also determined in primary explant cultures exposed to GenOx Inorg(®) (1 : 1 with MR) for 7 days. Data were compared using either the Mann-Whitney U-test or the Kruskal-Wallis test. RESULTS: MS cultures exhibited a significantly lower osteogenic potential compared with MR cultures, with a progressive increase in cell proliferation together with a decrease in osteoblast markers, reduced ALP activity and calcium content. Exposure of MR-derived primary cultures to GenOx Inorg(®) inhibited ALP activity. CONCLUSION: These results suggest that the use of GenOx Inorg(®) in combination with MR fragments for MS floor augmentation inhibits the osteoblast cell differentiation at the implant site in the long term.

Maxillary sinus grafting with biphasic calcium phosphate ceramics: clinical and histologic evaluation in man.

PURPOSE: To evaluate the clinical and histologic aspects of bone formation in maxillary sinus augmentation using macroporous biphasic calcium phosphate (MBCP) comprising hydroxyapatite/tricalcium phosphate (HA/TCP) 60/40 as bone-grafting material. MATERIALS AND METHODS: A total of 10 patients and 12 sinuses grafted with MBCP in two-stage sinus augmentation were included in the present study. After a healing period of 6 months, bone core biopsies were harvested during implant insertion and evaluated under light microscopy. RESULTS: The histologic examination showed that the MBCP particles were in close contact with new bone in all biopsies. Histomorphometric evaluation demonstrated that newly formed bone constituted 28.3% ± 2.7%, residual grafted material 27.3% ± 1.2%, and marrow spaces 45.9% ± 1.9%. CONCLUSIONS: Histologic investigation showed that the MBCP grafted particles were embedded and integrated in the newly formed bone; this bone was in close and tight contact with the biomaterial particles. Data from the preliminary results demonstrated that MBCP is a biocompatible and osteoconductive material that can be successfully used as a grafting material for sinus floor augmentation.

Radiographic and histologic evaluation of platelet-rich plasma and bovine-derived xenograft combination in bilateral sinus augmentation procedure.

There is currently a great interest regarding the use of platelet-rich plasma (PRP) in combination with various bone graft materials in sinus lift procedures. The purpose of this study was to assess and compare the radiographic and histological results of sinus augmentation procedures following treatment with PRP/bovine-derived xenograft (BDX) vs. BDX/collagen membrane. Using a split mouth design, 10 patients, with ≤5 mm of residual alveolar bone in the vertical direction, were treated with PRP/BDX or BDX/collagen membrane. At 8 months after surgery, both graft materials led to a satisfactory increase in vertical dimensions of bone. Bone biopsies were taken from the augmented sites during the implant placement. Histological analysis demonstrated that majority of the trabecula contained orderly layered lamellar bone in the PRP/BDX group, whereas mainly woven bone with a haphazard arrangement of collagen fibers were noticed in the BDX /collagen membrane group. It can be concluded that both combinations resulted with a satisfactory bone height, but more prominent and mature bone formation was observed at sites treated with PRP/BDX.

Apoptosis as a mechanism of maxillary sinus mucosa injury in rats after experimental transection of the maxillary nerve.

Transection of the maxillary nerve initiates apoptosis of the maxillary sinus mucosa cells in rats. Significant activation of apoptosis and proapoptotic factor p53 was found in the epithelium during week 1 after nerve transection. In delayed period after injury, apoptotic cells predominated in the submucosa against the background of Bcl-2 hypoexpression.

Infraorbital ethmoid (Haller's) cells: a panoramic radiographic study.

OBJECTIVE: Haller's cells or infraorbital ethmoid cells refer to the ethmoidal pneumatization of the superior aspect of the maxillary sinus and floor of the orbit. The clinical importance of these entities initiated this study with an aim to determine the prevalence and characteristics of Haller's cells on panoramic radiographs. METHODS: The study group comprised 600 healthy adults of both genders with an age range of 18-60 years. One panoramic radiograph for each of the patients was made and interpreted for the presence of Haller's cells. The data collected were subjected to statistical analysis: frequencies/percentages, descriptive statistics, χ(2) test and cross-tabulation (contingency table analysis) to obtain the results. RESULTS: Haller's cells were noted in 96 patients, accounting for a prevalence of 16%. Of these patients, 77.1% were unilateral while 22.9% were bilateral. Among 96 cases, a total of 204 cells were found. The majority of the cells were round or ovoid in shape. The unilocular type of Haller's cells occurring unilaterally was statistically significant. CONCLUSION: This study has attempted to explore the characteristics of Haller's cells on panoramic radiographs. A description of Haller's cells on these radiographs may prove vital in enumerating the differential diagnosis for patients afflicted with intractable orofacial pain and reduce the risk of untoward intraoperative complications during endonasal procedures.

Bone production by human maxillary sinus mucosa cells.

The Schneider membrane is the mucosa that covers the inner part of the maxillary sinus cavities. The free surface is a ciliated pseudostratified epithelium, while the deeper portion is a highly vascularized connective tissue. The stromal fraction, bordering the bony wall of the sinus, after tooth loss can exhibit increased osteoclastic activity resulting in resorption of the bone in the posterior maxilla. Goal of our study was to isolate and characterize mesenchymal progenitors in the Schneider's membrane connective net and to evaluate their self ability to differentiate toward osteoblastic lineage, in absence of osteoinductive factors and osteoconductive biomaterials of support. This should indicate that maxillary sinus membrane represents an useful an approachable source of MSCs for bone tissue engineering and cell therapy and owns the intrinsic capacity to restore maxillary bone after tooth loss without the needing of biomaterials.

Maxillary sinus floor elevation using a tissue-engineered bone with rhBMP-2-loaded porous calcium phosphate cement scaffold and bone marrow stromal cells in rabbits.

The aim of this study was to evaluate the effects of maxillary sinus floor elevation by a tissue-engineered bone complex with recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded porous calcium phosphate cement (CPC) scaffold and bone marrow stromal cells (bMSCs) in rabbits. bMSCs were cultured and osteogenically induced. The osteoblastic differentiation of expanded bMSCs was detected by alkaline phosphatase activity, and calcium deposits in vitro. Thirty-six rabbits were randomly allocated into week 2, 4 and 8 observation groups. At each time point, 24 maxillary sinus floor elevation surgeries in 12 rabbits were performed bilaterally and randomly implanted by (1) CPC materials alone (group A, n = 6), (2) rhBMP-2/CPC composite materials alone (group B, n = 6), (3) CPC/bMSCs complex (group C, n = 6) and (4) rhBMP-2/CPC/bMSCs complex (group D, n = 6). As for maxillary sinus floor elevation, rhBMP-2-loaded CPC could promote new bone formation as compared to CPC, while addition of bMSCs could further enhance its new bone formation and maturity significantly, as detected by histological findings, and fluorochrome labeling. Our data suggested that rhBMP-2/CPC possessed excellent osteoinductive ability, while combining with bMSCs could further promote new bone formation and maturation in maxillary sinus elevation.

Closure of oroantral communications using biodegradable polyurethane foam: a long term study in rabbits.

An oroantral communication (OAC) is an open connection between the oral cavity and maxillary sinus. Closure of OACs is commonly performed with a surgical procedure using a mucoperiosteal flap. An alternative technique using synthetic biodegradable polyurethane (PU) foam for closure of OACs is presented. This PU foam is composed of hard urethane segments, and soft segments made of D/L lactide (50/50), epsilon-caprolactone, and 5% polyethyleneglycol (PEG). To evaluate the use of PU foam for this application, OACs were created in the edentulous part of the maxilla in 21 rabbits, after which PU foams were fitted in the defects. Results showed complete healing of the oral mucosa after 4-10 weeks, healing of the antral mucosal lining after 6 months and complete bony regeneration after 1 year. No reopening of the defects occurred and no maxillary sinusitis was observed. Degradation of the PU foam had not yet reached completion 1 year after implantation. In conclusion, PU foam with 5% PEG provides adequate closure of an OAC in the rabbit model to support healing of the oral and maxillary sinus mucosa. Longer time intervals are needed to assess the complete degradation of the PU foam.