氟磷灰石晶体—聚己内酯纳米纤维抗菌支架在诱导牙周组织再生中的研究

Tissue engineering technique has shown a promising future in periodontal regeneration. However, it has not been widely used in clinic therapy, mostly because that the tissue engineering scaffolds couldn’t efficiently support and induce stem cells adhering，growing and differentiating in the bacteria-induced inflammatory environment...Our previous study showed that a fluorapatite coated polycaprolactone nanofiber scaffold supported the growth, differentiation and mineralization of periodontal ligament stem cells (PDLSCs). This fluorapatite modified polycaprolactone scaffold served as an excellent in vitro model for studying the mechanisms underlying the stem cell differentiation and mineralization process in a biomimetic micro environment. Most importantly, this fluorapatite modified polycaprolactone nanofiber construction is a new biomimetic material, which has the promising potential to be used as a multi-purpose scaffolds in tissue engineering regeneration of periodontal tissues...In this study, the polycaprolactone nanofibers will be modified with different sizes and shapes of fluorapatite crystals. The physical, chemical, biological characteristics and micro-topographies of the composite scaffolds will be analyzed. The degradation rate and antibacterial ability of the scaffolds will be studied. The behaviors of stem cells seeded on these scaffolds will be analyzed. Eventually, the capability of fluorapatite modified polycaprolactone used as a scaffold for periondontal tissue regeneration will be tested and evaluated.

牙周组织工程技术应用前景良好，但“在有菌的炎性环境中按需再生牙周组织”的目标尚未实现。前期研究结果发现牙周膜干细胞接种于氟磷灰石晶体—聚己内酯纳米纤维支架上，不需额外诱导即可向成骨细胞分化，同时支架降解过程中持续缓释高浓度氟离子，表明其有成为牙周组织工程支架的可能。但支架的理化性质、诱导牙周膜干细胞分化的机理尚不明确，仍需进一步研究。本研究将在前期工作基础上对氟磷灰石晶体—聚己内酯纳米纤维支架中晶体的形态、成分比例精确调控，表征复合支架的理化、生物性能，调节支架降解速度及抑菌能力，建立其性能评判标准。进一步研究支架结构组成及微地形的差异对牙周膜干细胞的内部结构、生物学行为、牙周局部菌群和炎症状态及牙周组织再生的影响。优选出可抵抗牙周致病菌干扰、结合干细胞即能诱导牙周组织再生的新型支架。提出由抗菌支架诱导干细胞分化、再生组织的新理念。以期研究结果为牙周组织工程技术临床转化奠定基础。

牙周组织工程技术目前的瓶颈问题是支架材料的选择和诱导因子的缓释。本研究在前期工作基础上研发出具有强抗菌能力、可独立诱导干细胞矿化分化的新型组织工程支架：氟磷灰石（fluorapatite，FA）—聚己内酯（polycaprolactone，PCL）纳米纤维三维支架。并通过对支架中FA晶体的形态、成分比例精确调控，合成了不同拓扑结构的支架。实验结果表明：各组支架均具有良好的生物相容性；各组支架中裸露的FA晶体均可独立诱导种子细胞矿化分化，从而规避了常规组织工程中使用诱导因子带来的免疫原性风险，避免了诱导因子缓释难以控制的问题；各组支架均可持续释放高浓度氟离子，起到抗菌的作用；其中纳米梭形晶体组的拓扑结构亲水性能最好，FA结晶程度最高。被优选用于牙周组织工程的进一步研究。动物实验证实：FA-PCL支架可以在裸鼠体内诱导异位成骨。但在牙周病动物模型体内实验中组织修复效果不够理想。分析原因，课题组认为支架强度不够、局部炎症难以控制是失败的主要原因。进一步研究发现：重度牙周炎病损经基础治疗后，龈沟液内牙龈卟啉单胞菌脂多糖（Porphyromonas gingivalis lipopolysaccharide, Pg-LPS）水平仍明显高于正常对照，而Pg-LPS刺激下牙周膜干细胞增殖分化能力明显下降。此外，课题组还发现自噬参与FA-PCL支架诱导牙周膜干细胞矿化分化的过程；及Pg-LPS下调牙周膜干细胞增殖分化能力的过程。.针对实验结果课题组已启动支架改良方案，正在研发钛网加强型FA-PCL纳米纤维三维支架。并计划通过调节牙周膜干细胞自噬强度，激活干细胞增殖分化能力后，再植入FA-PCL支架，以重建牙周组织。.本研究结果为组织工程技术临床转化提供新的思路和方法，为牙周组织工程技术真正转化为临床治疗手段奠定基础。