In vitro wound healing responses to enamel matrix derivative

BACKGROUND: Enamel matrix derivative (EMD) contains a variety of hydrophobic enamel matrix proteins and is extracted from developing embryonal enamel of porcine origin. EMD has been associated with the formation of acellular cementum and it has been found to stimulate periodontal regeneration. The present study was established to investigate the influence of EMD on human periodontal ligament (PDL) cells, gingival fibroblasts (GF), and osteosarcoma (MG-63) cells on wound-fill rates using an in vitro wound model. METHODS: Wounds were created by making 3 mm incisions in cell monolayers across the length of tissue culture plates. The wounded PDL, GF, and MG-63 cell monolayers were treated with media containing EMD over a concentration range of 5 to 100 microg/ml, platelet-derived growth factor (PDGF-BB) at 20 ng/ml as a positive control and insulin-like growth factor (IGF-I) at 100 ng/ml as a negative control. PDL cell wounded monolayers also were treated in EMD coated tissue culture plates. After an incubation period (up to 9 days), the cells were fixed and stained and cellular fill was measured across the width of the wound by computer-assisted histomorphometry. RESULTS: When PDL, GF, and MG-63 cells were exposed to EMD in culture medium, an enhanced wound-fill was observed for all cells compared to untreated conditions. At early time points, PDL wound-fill rates in the presence of EMD were statistically greater than the rates of GF and MG-63 treated with EMD (P<0.001). There were no significant differences in wound-fill rates of PDL cells treated with EMD in medium versus EMD coated on culture plates. At days 3 and 6 post-wounding, PDL cells showed a significantly greater response to EMD than to PDGF-BB (P <0.001). EMD also had a greater effect on GF wound-fill rates than PDGF-BB at days 6 and 9. MG-63 cells were less responsive to PDGF-BB and EMD than PDL cells and GF. All 3 cell types treated with IGF-I showed no significant increase of wound-fill rates. CONCLUSION: The present data support the concept that clinical application of enamel matrix derivative may enhance periodontal wound regeneration by specifically modifying periodontal ligament cell proliferation and migration.     

In vitro studies on periodontal ligament cells and enamel matrix derivative

Abstract The recognition that periodontal regeneration can be achieved has resulted in increased efforts focused on understanding the mechanisms and factors required for restoring periodontal tissues so that clinical outcomes of such therapies are more predictable than those currently being used. In vitro models provide an excellent procedure for providing clues as to the mechanisms that may be required for regeneration of tissues. The investigations here were targeted at determining the ability of enamel matrix derivative (EMD) to influence specific properties of periodontal ligament cells in vitro. Properties of cells examined included migration, attachment, proliferation, biosynthetic activity and mineral nodule formation. Immunoassays were done to determine whether or not EMD retained known polypeptide factors. Results demonstrated that EMD under in vitro conditions formed protein aggregates, thereby providing a unique environment for cell-matrix interaction. Under these conditions, EMD: (a) enhanced proliferation of PDL cells, but not of epithelial cells; (b) increased total protein production by PDL cells; (c) promoted mineral nodule formation of PDL cells, as assayed by von Kossa staining; (d) had no significant effect on migration or attachment and spreading of cells within the limits of the assay systems used here. Next, EMD was screened for possible presence of specific molecules including: GM-CSF, calbindin D, EOF, fibronectin, bFGF, γ-interferon. IL-1β, 2, 3, 6; IGF-1,2; NGF, PDGF, TNF, TGFβ. With immunoassays used, none of these molecules were identified in EMD. These in vitro studies support the concept that EMD can act as a positive matrix for cells at a regenerative site.     

In vitro effects of enamel matrix proteins on rat bone marrow cells and gingival fibroblasts

Emdogain (EMD), a formulation of Enamel Matrix Proteins (EMP), is used clinically for periodontal regeneration, where it stimulates cementum formation and promotes gingival healing. In this study, we investigated the in vitro effects of EMD on rat bone marrow stromal cells (BMSC) and gingival fibroblasts (GF). EMD (at 25 micro g/mL) increased the osteogenic capacity of bone marrow, as evidenced by approximately three-fold increase in BMSC cell number and approximately two-fold increase in alkaline phosphatase (ALP) activity and mineralized nodule formation. The presence of EMD in the initial stages (first 48 hrs) of the culture was crucial for this effect. In contrast, EMD did not induce osteoblastic differentiation of GF (evidenced by lack of mineralization or ALP activity) but increased up to two-fold both their number and the amount of matrix produced. These in vitro data on BMSC and GF could explain the promotive effect of EMD on bone formation and connective tissue regeneration, respectively.     

釉基质蛋白对猪骨髓基质细胞黏附、伸展及增殖的影响

目的：研究釉基质蛋白（enamel matrix proteins,EMPs）对体外培养的猪骨髓基质细胞（bone marrow stromal cells,BMSCs）黏附、伸展和增殖活性的影响。方法：抽取猪髂骨骨髓．全血培养法获得骨髓基质细胞。培养液中EMPs的浓度分别为25、50、100、200μg／ml,以不加EMPs为对照。用比色法检测不同浓度EMPs对BMSCs黏附的影响。通过计数预定视野中伸展的细胞数,计算BMSCs在培养1h、3．5h、6、5h后的伸展率。MTT法测定各组细胞的增殖活性。对实验数据行单因素方差分析和SNK法组间比较。结果：猪BMSCs在含有EMPs的培养液中生长良好。对照组以及不同浓度EMPs实验组对细胞黏附的影响无统计学差异。在1h、3．5h、6．5h．各组细胞的伸展率无显著不同。EMPs对BMSCs的促增殖作用呈浓度和时间依赖性．200μg／ml浓度的EMPs从实验的第3天开始．显著促进猪BMSCs的增殖。结论：EMPs对体外培养的猪BMSCs的黏附和伸展无显著影响．200μg／ml浓度的EMPs可显著促进猪BMSCs增殖,为联合应用EMPs和BMSCs修复牙周组织缺损提供了理论依据。     

釉基质蛋白对猪骨髓基质细胞增殖和根面附着生长的影响

目的:研究釉基质蛋白(enamel matrix proteins,EMPs)对体外培养的猪骨髓基质细胞(bone marrowstrom alcells,BMSCs)增殖和在根面附着生长的影响,为EMPs联合应用BMSCs修复牙周组织缺损提供理论依据。方法:抽取猪髂骨骨髓,全血培养法获得骨髓基质细胞。培养液中EMPs的浓度分别为25、50、100、200μg/ml,以不加EMPs为对照。MTT法测定各组细胞的增殖活性。对实验数据行单因素方差分析和SNK法组间比较,检验水准为α=0.05。制备猪自体牙根片,以200μg/mlEMPs处理组为实验组,对照组不用EMPs处理。接种BMSCs后培养7d,HE染色和扫描电镜观察。选取800倍下标准视野,计数每个视野中的细胞数,取4个视野均值。采用配对t检验法作统计学分析,检验水准为α=0.05。结果:猪BMSCs在含有EMPs的培养液中生长良好。EMPs对BMSCs的促增殖作用呈浓度和时间依赖性,200μg/ml浓度的EMPs从实验的第3天开始显著促进猪BMSCs增殖。HE染色显示BMSCs在根片表面附着良好。扫描电镜观察表明实验组附着生长的BMSCs数量较多,与对照组相比具有显著差异。结论:EMPs在200μg/ml浓度时可显著促进猪BMSCs增殖,并促进其在根面的附着生长,提示EMPs和BMSCs可以联合应用以修复牙周组织缺损。     

釉基质蛋白对大鼠骨髓基质细胞合成非胶原蛋白的影响

目的探讨釉基质蛋白对大鼠骨髓基质细胞合成非胶原蛋白的影响。方法采用全骨髓法培养大鼠骨髓基质细胞,通过免疫细胞化学和图像分析方法观察釉基质蛋白对骨髓基质细胞合成骨桥蛋白、骨涎蛋白的影响。结果实验组非胶原蛋白合成明显强于对照组。结论一定浓度的釉基质蛋白可以有效促进骨桥蛋白、骨涎蛋白的合成。     

大鼠颌骨与髂骨来源骨髓基质干细胞的体外生物学特性比较

目的比较大鼠颌骨与髂骨来源的骨髓基质干细胞(bone marrowstromal cells,BMSCs)的体外生物学特性差异。方法采用贴壁法分离培养大鼠颌骨与髂骨来源的BMSCs,从细胞生长特点,诱导矿化及成脂能力等方面比较两者的体外生物学特性。结果颌骨来源的BMSCs与髂骨来源的相比,具有更强的增殖能力,矿化诱导后形成更多的钙结节(P<0.05);而髂骨来源BMSCs在成脂诱导条件下形成更多脂质(P<0.05)。结论不同部位来源的BMSCs具有不同的生物学特点,颌骨来源的BMSCs具有更强的增殖和诱导后形成更多钙结节的能力,这为进一步研究颌骨病变与再生修复机制提供细胞学模型。     

牙骨质基质和骨基质对骨髓基质细胞体外钙化的影响

目的：研究骨髓基质细咆任牙骨质和骨片表面生长细胞表型发育的情况。方法：将骨髓基质细胞与牙骨质片和股骨片在体外共同培养，分别在第7d、第28d进行形态学观察，并用放射免疫的方法测定上清液中骨钙素的含量。结果：骨髓基质细胞在牙骨质片和骨片表面生长良好，但细胞形态不同，两组上清液中均有骨钙素的生成，骨片组较牙骨质片组的含量高，第28d骨钙素分泌量高于7d。结论：结果表明生长于牙骨质片和骨片表面的骨髓基质细胞在体外矿化液培养条件下可向成骨样细胞转化，但细胞表现型有所区别。     

Correlation of in vivo bone formation capability and in vitro differentiation of human bone marrow stromal cells

Although human bone marrow stromal cells (MSCs) have been used for clinical bone reconstruction, how the physiological status of patients and culture conditions of MSCs affect the result of bone reconstruction must be clarified to use MSCs in a clinical stage. If in vitro parameters of the status of MSCs may be correlate with in vivo bone formation capability, the better cells for clinical bone reconstruction can be defined by the parameters. In order to explore the parameters and define the optimum cells for clinical use, the proliferation and differentiation capabilities in vitro and the in vivo bone formation capability of MSCs were analyzed. An age-related proliferation capability was found. The in vitro alkaline phosphatase activity of bone formation finding groups was higher than that of the no bone formation group. This may be provide a parameter to obtain the optimum cells for clinical use to benefit improving the cure efficiency. In this study, it is preferable that MSCs of passage 1 have stronger osteogenic potential than those of passage 2 and 3 in vitro, and might be suitable for clinical application to bone tissue engineering.     

In vitro assessment of motility and proliferation of human osteogenic cells on different isolated extracellular matrix components compared with enamel matrix derivative by continuous single-cell observation

OBJECTIVES: The composition of the extracellular matrix (ECM) plays a substantial role in bone remodelling, fracture healing and osseointegration of dental implants by regulating proliferation, migration and finally differentiation of osteogenic cell populations. Emdogain, a composition of an enamel matrix derivative (EMD), has been introduced as a potential candidate to promote tissue regeneration. We investigated whether EMD could serve as a potential promoter of cell proliferation and motility as a dynamic cell response and compared the results with the ubiquitous single ECM components type I collagen and laminin. MATERIAL AND METHODS: In the investigation presented, we used a continuous observation method for the analysis of migratory and proliferative patterns of individual cells. We analyzed the response of four osteoblastic cell lines to specific extracellular ligands (type I collagen, laminin and EMD) over a period of 24 h compared with untreated glass surface and bovine serum albumin (BSA) as control groups. RESULTS: Type I collagen and laminin promoted cell motility significantly compared with the control groups and, in part, compared with EMD as well. The analysis of all 451 investigated cells revealed the following mean values for cell motiliy: untreated glass (n=99): 5.46+/-2.74 microm/h, BSA (n=89): 6.35+/-2.43 microm/h, type I collagen (n=108): 8.77+/-3.42 microm/h, laminin (n=74): 9.89+/-5.10 microm/h and EMD (n=81): 7.92+/-3.35 microm/h. Proliferation rates on the different surfaces were heterogenous for all investigated cell lines and varied from 0% to 50% within 24 h without a correlation to cell motility. CONCLUSION: In our study, EMD promotes cell motility better than the control groups. The two investigated single ECM components type I collagen and laminin promoted cell motility superior to EMD. This supports the hypothesis that EMD promotes a less mobile but more differentiated osteogenic phenotype.     

培养状态下成人骨髓基质细胞的生长特性

目的研究培养状态下成人骨髓基质细胞的生长特性,为自体骨组织工程的功能细胞培养提供实验基础研究。方法培养健康成人骨髓基质细胞连续8代,测定第3、6代细胞的生长曲线、分裂指数、贴壁率及倍增时间。结果所测第3、6代细胞生长曲线基本相同,12h内细胞贴壁率达88.54%,分裂指数最高达15‰。结论在本实验条件下,细胞生长较稳定,接种成活率较高,增殖速度较快,可用于自体骨组织工程。     

Anti-inflammatory properties of enamel matrix derivative in human blood

BACKGROUND AND OBJECTIVE: Enamel matrix derivative (EMD), extracted from porcine tooth buds, has been shown to promote periodontal healing in patients with severe periodontitis. This involves modulation of the inflammatory response followed by the onset of periodontal regeneration. Based on these observations, we examined the ability of EMD to modulate the release of a pro-inflammatory cytokine [tumor necrosis factor (TNF)-alpha], an anti-inflammatory cytokine (interleukin-10) and a chemokine (interleukin- 8) in whole human blood challenged by bacterial cell wall components. MATERIAL AND METHODS: Whole blood from healthy donors was challenged by lipopolysaccharide or peptidoglycan and incubated with different concentrations of EMD or a cAMP analogue 8-(4-chlorophenyl)thio-cAMP (8-CPT-cAMP). TNF-alpha, interleukin-8 and interleukin-10 were analysed from plasma by enzyme-linked immunosorbent assay (ELISA) while cAMP levels of peripheral blood mononuclear cell lysates were analysed by enzyme immunoassay (EIA). RESULTS: We found that EMD attenuated the release of TNF-alpha and interleukin-8 in whole blood from healthy donors challenged by lipopolysaccharide or peptidoglycan, while the release of interleukin-10 was unchanged. Enamel matrix derivative also produced a four-fold increase in the cAMP levels of peripheral blood mononuclear cell lysates. Like EMD, 8-CPT-cAMP attenuated the formation of TNF-alpha, but not of interleukin-10, in blood challenged by lipopolysaccharide. CONCLUSION: Enamel matrix derivative limits the release of pro-inflammatory cytokines induced by lipopolysaccharide or peptidoglycan in human blood, suggesting that it has anti-inflammatory properties. We propose that this effect of EMD is, at least partly, secondary to an increase in the intracellular levels of cAMP in peripheral blood mononuclear cells.     

Disparate osteogenic response of mandible and iliac crest bone marrow stromal cells to pamidronate

Objective:  Long-term administration of intravenous bisphosphonates like pamidronate is associated with jaw osteonecrosis but axial and appendicular bones remain unaffected. Pathogenesis of bisphosphonate-associated jaw osteonecrosis may relate to skeletal site-specific effects of bisphosphonates on osteogenic differentiation of bone marrow stromal cells (BMSCs) of orofacial and axial / appendicular bones. This study evaluated and compared skeletal site-specific osteogenic response of mandible (orofacial bone) and iliac crest (axial bone) human BMSCs to pamidronate.
Materials and methods:  Mandible and iliac crest BMSCs from six normal healthy volunteers were established in culture and tested with pamidronate to evaluate and compare cell survival, osteogenic marker alkaline phosphatase, osteoclast differentiation in co-cultures with CD34⁺ hematopoietic stem cells, gene expression of receptor activator of NFκB ligand (RANKL) and osteoprotegerin, and in vivo bone regeneration.
Results:  Mandible BMSCs were more susceptible to pamidronate than iliac crest BMSCs based on decreased cell survival, lower alkaline phosphatase production, and structurally less organized in vivo bone regeneration. Pamidronate promoted higher RANKL gene expression and osteoclast recruitment by mandible BMSCs.
Conclusion:  Mandible and iliac crest BMSC survival and osteogenic differentiation are disparately affected by pamidronate to favor dysregulated mandible bone homeostasis.     

Autocrine growth factors in human periodontal ligament cells cultured on enamel matrix derivative

OBJECTIVE: Enamel extracellular matrix proteins in the form of the enamel matrix derivative EMDOGAIN (EMD) have been successfully employed to mimic natural cementogenesis to restore fully functional periodontal ligament, cementum and alveolar bone in patients with severe periodontitis. When applied to denuded root surfaces EMD forms a matrix that locally facilitates regenerative responses in the adjacent periodontal tissues. The cellular mechanism(s), e.g. autocrine growth factors, extracellular matrix synthesis and cell growth, underlying PDL regeneration with EMD is however poorly investigated. MATERIAL AND METHODS: Human periodontal ligament (PDL) cells were cultured on EMD and monitored for cellular attachment rate, proliferation, DNA replication and metabolism. Furthermore, intracellular cyclic-AMP levels and autocrine production of selected growth factors were monitored by immunological assays. Controls included PDL and epithelial cells in parallel cultures. RESULTS: PDL cell attachment rate, growth and metabolism were all significantly increased when EMD was present in cultures. Also, cells exposed to EMD showed increased intracellular cAMP signalling and autocrine production of TGF-beta1, IL-6 and PDGF AB when compared to controls. Epithelial cells increased cAMP and PDGF AB secretion when EMD was present, but proliferation and growth were inhibited. CONCLUSION: Cultured PDL cells exposed to EMD increase attachment rate, growth rate and metabolism, and subsequently release several growth factors into the medium. The cellular interaction with EMD generates an intracellular cAMP signal, after which cells secrete TGF-beta1, IL-6 and PDGF AB. Epithelial cell growth however, is inhibited by the same signal. This suggest that EMD favours mesenchymal cell growth over epithelium, and that autocrine growth factors released by PDL cells exposed to EMD contribute to periodontal healing and regeneration in a process mimicking natural root development.     

体外培养的大鼠骨髓基质细胞的生物学特性

目的：研究体外培养的大鼠骨髓基质细胞的生物学特性及基成骨细胞表型特征。方法：分离大鼠四肢长骨髓基质细胞,常规和矿化培养液培养,测定细胞生长曲线,碱性成纤细胞生长因子（bFGF）、重组人骨形成蛋白－2（rhBMP-2)及矿化培养液对骨髓基质细胞性磷酸酶（ALP）活性的影响,观察矿化结节的形成。结果：大鼠骨髓基质细胞群体倍增时间（DT）为66．1h;在矿化液培养条件下细胞DT为50．3h。bFGF和rhBMP－2均不同程度增加骨髓基质细胞碱性磷酸酶的活性。矿化液有较明显的增加骨髓基质细胞碱性磷酸酶活性的作用,用茜素红染色法显示较多的深红色矿化结节。常规培养条件下大鼠骨髓基质细胞生长虽呈现密集单层,没有矿化结节形成。结论：大鼠骨髓基质细胞在体外可以稳定传代培养,在矿化培养液诱导培养条件下可以向成骨细胞分化,bFGF和rhBMP－2有助于骨髓基质细胞表现成骨细胞表型特征,提示骨髓基质细胞在骨移植研究领域有重要的应用价值。