牙乳头细胞复合海藻酸钠-聚乳酸羟基乙酸共聚物构建组织工程牙根

背景：牙胚组织工程重建研究表明牙齿结构可用组织工程方法构建，牙齿存活及行使功能的关键在于牙根及其牙周附着，那么是否可以绕开具有复杂组织结构的完整牙齿组织工程概念的束缚，而将组织工程构建目标仅仅指向结构单一的牙根组织？ 目的：采用组织工程方法，以牙乳头细胞为种子细胞，海藻酸钠-聚乳酸羟基乙酸共聚物为支架材料构建兔组织工程牙根。 方法：分离、培养扩增兔牙乳头细胞，离心收集细胞混于海藻酸钠水凝胶，制成浓度6×10⁹ L^-1的细胞悬液，接种到人牙根状聚乳酸羟基乙酸共聚物支架中，用CaCl₂固化后，构建出细胞-支架复合物，然后移植于裸鼠背部皮下，植入后4，8周取材，进行大体标本、X射线、三维CT、组织学及免疫组织化学染色观察。 结果与结论：经4-8周体内移植后获得的组织定型于牙根形状。植入4周后，标本密度较低；牙根移植物出现矿化，但矿化不完全，海藻酸钠水凝胶已降解，聚乳酸羟基乙酸共聚物支架未降解；标本中出现了大量类牙本质结构，在标本表面具有纤维膜结构，与根面平行，结构不连续，没有明显髓腔形成。植入后8周，标本密度增高，更为接近自然生长的牙根组织；牙根移植物矿化基本完成，聚乳酸羟基乙酸共聚物支架已大部分降解；标本中出现了大量类似于成熟牙本质的结构，在标本表面形成连续的纤维膜结构，与根面平行，在其下方开始有类似牙骨质样结构的形成。表明采用工程方法可建出具有基本组织学类型和结构的类似人工牙根组织。

Constructing a tissue-engineered dental root by seeding dental papilla cells into poly(lactic-co-glycolic acid)/sodium alginate hydrogel

BACKGROUND:Studies addressing reconstruction of tooth tissue engineering have shown that tooth structure can be constructed using tissue engineering technology. Tooth root and its periodontal attachment are critical for tooth survival and functions, based on which, whether we can target root tissues with simple structure for tissue engineering construction by bypassing a complex dental tissue engineering concept with the structural integrity? OBJECTIVE:To construct a tissue-engineered dental root by seeding dental papilla cells, as seed cells, into poly(lactic-co-glycolic acid)/sodium alginate hydrogel. METHODS:Rabbit dental papilla cells were isolated and cultured. The cells were then mixed with 1% sodium alginate hydrogel at a final density of 6×10⁹/L. The cell suspension was seeded into a poly(lactic-co-glycolic acid) scaffold with predetermined shape of human tooth and solidified with calcium chloride. Finally, the cell-scaffold composites were subcutaneously implanted into the back of nude mice. The specimens were harvested after 4 and 8 weeks respectively and processed for gross inspection, X-ray and CT examination and histological observation. RESULTS AND CONCLUSION:The newly formed tissue kept the original shape of human dental root 4 and    8 weeks post-implantation. After 4 weeks of implantation, the specimen density was low; the root implants appeared to be incompletely mineralized, alginate hydrogels were degraded, but the copolymer scaffold was not degraded; a number of dentin-like structure appeared, and a fibrous membrane structure was visible on the surface of specimens parallel to the root surface, but the structure was not continuous, and no pulp cavity formed. After 8 weeks, the newly formed tissue was highly mineralized close to root tissue of the nature tooth; the copolymer scaffold was mostly degraded; specimens appeared to have a large number of mature dentin-like structure, and form continuous fibers membrane on the surface parallel to the root surface, below which, cementum-like structure formed. Artificial dental root with biologically similar structures of human dental roots can be constructed using the method of tissue engineering.