牛血浆纤维粘连蛋白对培养的鼠牙乳头组织的影响

目的观察牛血浆纤维粘连蛋白（ｆｉｂｒｏｎｅｃｔｉｎ，ＦＮ）对牙乳头组织及细胞的作用。方法对大鼠牙乳头和牙胚组织进行器官培养，实验组将微孔滤膜用８０ｍｇ／ＬＦＮ液浸润２ｈ，然后将牙乳头组织置薄膜上培养３、６天，同时设对照组，牙胚培养３、６、９天，常规组织学染色。结果牙胚在体外可有成牙本质细胞分化和前期牙本质的形成。实验组于牙乳头组织和滤膜交界处出现极化细胞，而对照组则未出现上述现象。结论ＦＮ参与了成牙本质细胞的极化过程。     

Mineralized nodule formation by human dental papilla cells in culture

Human dental papilla cells were enzymatically separated from deciduous tooth germs of an 8-month-old embryo legally aborted. the second passage cells were cultured up to 35 days in 3 groups. The β-gp group was cultured in the Dulbecco MEM containing ascorbic acie and β-glycerophosphate supplemented with 15% fetal bovine serum. The Dex group was in the same medium, in addition containing dexamethasone. The Control group contained none of the 3 chemicals, Mineralized nodules were formed after 15 days in the β-GP and Dex groups. Only in the presence of ascorbic acid and organic phosphate did they mineralize. The addition of dexamethasone caused a significant increase in the number of nodules. By electron microscopy, the nodules contained needle-shaped crystals associated with a network of collagen fibrils. Calcium and phosphorus were detected by energy-dispersive X-ray diffiractometry. Cells showed high levels of alkaline phosphatase activity, which was increased 2∼3 times in the presence of the 3 chemicals. These results indicated that human dental papilla cells have the ability to from dentin in culture. The formation of mineralized nodules by human dental papilla in vitro provides a useful model for studying the morphogenesis and differentiation of dental papilla cctomesenchyme.     

Human gingival tissues in culture synthesize three metalloproteinases and a metalloproteinase inhibitor

Explants of human gingiva obtained during periodontal surgery and maintained in tissue culture synthesized three metalloproteinases which degraded collagen, gelatin, and proteoglycan respectively. Collagenase and gelatinase were present in both active and latent forms suggesting that collagen degradation was taking place. Proteoglycan degrading activity, however, was present only in the latent form.
Human gingival fibroblasts in monolayer culture did not synthesize metalloproteinases, but did produce an inhibitor with properties similar to the purified inhibitor TIMP (Tissue Inhibitor of Metallo-Proteinases) synthesized by rabbit bones in culture. Human gingival fibroblast inhibitor had an apparent molecular weight of 32,000 on gel filtration and blocked the activity of all three metalloproteinases.
These findings indicate that further investigation of the factors that control or modify metalloproteinase and TIMP activity in gingival tissues should help clarify the pathogenic mechanisms responsible for connective tissue loss in periodontal disease.     

cbfa1在人牙乳头细胞中的免疫组织化学研究

目的：构建pcDNA3-cbfal重组质粒，瞬时转染人牙乳头细胞，观察cbfal在转染前后的表达。方法：用EcoRV和XbaⅠ双酶切pcDNA3空载体和pGEM-5z-f-cbfal质粒，电泳回收后进行连接，连接产物转化DH5α，进行酶切鉴定和PCR分析。采用脂质体法瞬时转染人牙乳头细胞，制备细胞爬片。免疫组织化学染色。结果：共挑出7个阳性转化子，酶切和PCR分析结果均显示重组质粒构建成功。正常人牙乳头细胞中cbfal表达阴性，瞬时转染24h后，cbfal表达阳性。结论：成功构建了pcDNA3-cbfal真核表达载体。人牙乳头细胞无cbfal的表达，当转染正义的cbfal重组质粒后出现cbfal的表达。为进一步研究cbfal在牙乳头细胞中的作用奠定了基础。     

Patients who seek but do not receive implant-stabilized dentures will probably remain unsatisfied when new conventional dentures are made

J Evid Base Dent Pract 2001;1:198-9     

Dental pulp stem cells in regenerative dentistry

Stem cells constitute the source of differentiated cells for the generation of tissues during development, and for regeneration of tissues that are diseased or injured postnatally. In recent years, stem cell research has grown exponentially owing to the recognition that stem cell-based therapies have the potential to improve the life of patients with conditions that span from Alzheimer’s disease to cardiac ischemia to bone or tooth loss. Growing evidence demonstrates that stem cells are primarily found in niches and that certain tissues contain more stem cells than others. Among these tissues, the dental pulp is considered a rich source of mesenchymal stem cells that are suitable for tissue engineering applications. It is known that dental pulp stem cells have the potential to differentiate into several cell types, including odontoblasts, neural progenitors, osteoblasts, chondrocytes, and adipocytes. The dental pulp stem cells are highly proliferative. This characteristic facilitates ex vivo expansion and enhances the translational potential of these cells. Notably, the dental pulp is arguably the most accessible source of postnatal stem cells. Collectively, the multipotency, high proliferation rates, and accessibility make the dental pulp an attractive source of mesenchymal stem cells for tissue regeneration. This review discusses fundamental concepts of stem cell biology and tissue engineering within the context of regenerative dentistry.     

CVD-grown monolayer graphene induces osteogenic but not odontoblastic differentiation of dental pulp stem cells

Objective

The objective was to investigate the potential of graphene (Gp) to induce odontogenic and osteogenic differentiation in dental pulp stem cells (DPSC).

Cellular death but not genetic damage in oral mucosa cells after exposure to digital lateral radiography

The aim of the present study was to evaluate DNA damage (micronucleus) and cellular death (pyknosis, karyolysis, and karyorrhexis) in exfoliated buccal mucosa cells from individuals following digital lateral radiography. A total of 30 healthy patients (15 men and 15 women) indicated to the orthodontic therapy were submitted to digital lateral X-ray. Exfoliated oral mucosa cells were collected immediately before the X-ray exposure and after 10 days. The results pointed out no significant statistically differences (p > 0.05) of micronucleated oral mucosa cells. On the other hand, X-ray was able to increase other nuclear alterations closely related to cytotoxicity such as karyorrhexis, pyknosis, and karyolysis. In summary, these data indicate that exposure to digital lateral radiography may not be a factor that induced chromosomal damage, but it is able to promote cytotoxicity.     

牙齿发育相关基因ADAM28在人牙乳头细胞中的定位分布研究

目的探讨牙齿发育相关基因金属蛋白酶解离素28(a disintegrin and metalloproteinase28,ADAM28)在人牙乳头细胞(human dental papilla cells,HDPC)中的定位分布及作用。方法应用基因重组技术构建真核表达质粒pcDNA3.1(+)-ADAM28,通过细胞培养、基因转染HDPC后,采用免疫荧光、RT-PCR及Western blot检测ADAM28在HDPC中的表达分布。结果成功构建并鉴定ADAM28真核质粒,瞬时转染HDPC72h后,HDPC的胞质和胞膜上均表达ADAM28蛋白,而两对照组均无表达。结论ADAM28在HDPC内能被正确地翻译、表达,可能作为一种胞质蛋白调控着牙源性间充质细胞的增殖和分化。     

Preferential recruitment of bone marrow-derived cells to rat palatal wounds but not to skin wounds

ObjectiveTo investigate the contribution of bone marrow-derived cells to oral mucosa wounds and skin wounds.BackgroundBone marrow-derived cells are known to contribute to wound healing, and are able to differentiate in many different tissue-specific cell types. As wound healing in oral mucosa generally proceeds faster and with less scarring than in skin, we compared the bone marrow contribution in these two tissues.DesignBone marrow cells from GFP-transgenic rats were transplanted to irradiated wild-type rats. After recovery, 4-mm wounds were made in the mucoperiosteum or the skin. Two weeks later, wound tissue with adjacent normal tissue was stained for GFP-positive cells, myofibroblasts (a-smooth muscle actin), activated fibroblasts (HSP47), and myeloid cells (CD68).ResultsThe fraction of GFP-positive cells in unwounded skin (19%) was larger than in unwounded mucoperiosteum (0.7%). Upon wounding, the fraction of GFP-positive cells in mucoperiosteum increased (8.1%), whilst it was unchanged in skin. About 7% of the myofibroblasts in both wounds were GFP-positive, 10% of the activated fibroblasts, and 25% of the myeloid cells.ConclusionsThe results indicate that bone marrow-derived cells are preferentially recruited to wounded oral mucosa but not to wounded skin. This might be related to the larger healing potential of oral mucosa.     

Calcium ion release from calcium hydroxide stimulated fibronectin gene expression in dental pulp cells and the differentiation of dental pulp cells to mineralized tissue forming cells by fibronectin

Aim The effect of calcium ions on dental pulp cells was examined and the mechanism of dentine bridge formation by calcium hydroxide was investigated. Methodology Human dental pulp cells were treated with high concentration of calcium or magnesium ions for 24 h and fibronectin gene expression was measured by the quantitative PCR method. Human dental pulp cells were then cultured on fibronecin‐coated dishes for 24 h, and osteocalcin and osteopontin gene expression, which are typical phenotypes of mineralized tissue forming cells, were measured by the quantitative PCR method. Results Fibronectin gene expression was stimulated by calcium ions dose‐dependently. On the other hand, magnesium ions did not influence fibronectin gene expression. Furthermore, pulp cells cultured on fibronectin‐coated dishes enhanced the expression of phenotypes of mineralized tissue forming cells. Conclusions Calcium ions released from calcium hydroxide stimulates fibronectin synthesis in dental pulp cells. Fibronectin might induce the differentiation of dental pulp cells to mineralized tissue forming cells that are the main cells to form dentine bridges, via contact with cells.