Photocross-linked alginate hydrogels, due to their biodegradability, biocompatibility, strong control for gelling kinetics in space and time, and admirable adaptability for in situ polymerization with a minimally invasive approach in surgical procedures, have created great expectations in bone regeneration. However, hydrogels with suitable degradation kinetics that can match the tissue regeneration process have not been designed, which limits their further application in bone tissue engineering. Herein, we finely developed an oxidation strategy for alginate to obtain hydrogels with more suitable degradation rates and comprehensively explored their physical and biological performances in vitro and in vivo to further advance the clinical application for the hydrogels in bone repair. The physical properties of the gels can be tuned via tailoring the degree of alginate oxidation. In particular, in vivo degradation studies showed that the degradation rates of the gels were significantly increased by oxidizing alginate. The activity, proliferation, initial adhesion, and osteogenic differentiation of rat and rabbit bone marrow stromal cells (BMSCs) cultured with/in the hydrogels were explored, and the results demonstrated that the gels possessed excellent biocompatibility and that the encapsulated BMSCs were capable of osteogenic differentiation. Furthermore, in vivo implantation of rabbit BMSC-loaded gels into tibial plateau defects of rabbits demonstrated the feasibility of hydrogels with appropriate degradation rates for bone repair. This study indicated that hydrogels with increasingly controllable and matchable degradation kinetics and satisfactory bioproperties demonstrate great clinical potential in bone tissue engineering and regenerative medicine and could also provide references for drug/growth-factor delivery therapeutic strategies for diseases requiring specific drug/growth-factor durations of action.

In recent years, photocrosslinked alginate hydrogel has been widely studied in bone tissue engineering, owing to its numerous advantages. However, there are still some shortcomings like insufficient mechanical strength and lack of bone induction. To compensate for these deficiencies, in this work, a novel doped strontium (Sr) photocrosslinked methacrylated alginate (Sr-PMA) hydrogel was developed. Photocrosslinked alginate hydrogel fabricated via crosslinking methacrylate-modified alginate under ultraviolet (UV) light was placed into strontium solutions to prepare Sr-PMA gel by chelating reaction. The chemical structures, swelling behaviors, degradation profiles, elastic moduli, Sr2+ ion release and surface morphology of the Sr-PMA hydrogel were characterized, and we found that physical properties of the gels can be tailored by varying concentration of Sr2+ ions. And MC3T3-E1 cell viability, proliferation and mineralization outside the hydrogel were also investigated. Further research on cell survival, multiplication, osteogenic differentiation of the cells encapsulated in Sr-PMA hydrogels were explored. In vitro studies of biological properties revealed that incorporation of Sr2+ into photocrosslinked alginate gels significantly improved osteogenic differentiation capabilities and mineralization via stimulating expression of osteogenesis related genes and proteins of the cells compared to strontium-free photocrosslinked alginate gels. The research demonstrates that the innovative Sr-PMA hydrogels possessing adjustable physical performances, excellent biocompatibility and osteogenic differentiation capabilities could be potentially applied to bone tissue engineering and regenerative medicine. Meanwhile, it also provides a reference for the modification of biological properties of biomaterials.

背景:光交联藻酸盐水凝胶以其良好的稳定性、可控性和生物相容性而备受关注,然而其作为骨组织工程支架仍存在不足之处,如强度不足、细胞黏附性能较差、缺乏骨诱导性等.目的:在光交联海藻酸盐水凝胶支架中复合锶离子,探究其机械和生物学性能变化.方法:在甲基丙烯酸酯化海藻酸盐形成光交联水凝胶后,分别浸泡于不同浓度(0,10,30,50,80,100 mmol/L)锶离子溶液中,制备携锶离子光交联海藻酸盐水凝胶,测量其溶胀率、弹性模量,并用扫描电镜和能谱仪分析材料表面形态和元素.将MC3T3-E1细胞分别接种于不同浓度携锶离子光交联海藻酸盐水凝胶表面,培养第4小时,Live/Dead染色观察细胞黏附情况;培养第3天,Live/Dead染色观察细胞伸展情况.结果 与结论:①扫描电镜显示,随着引入锶离子浓度的升高,携锶离子光交联海藻酸盐水凝胶的致密程度增加,孔径减小;②能谱仪检测显示,随着引入锶离子浓度的增加,携锶离子光交联海藻酸盐水凝胶表面锶离子含量递增;⑨随着引入锶离子浓度的增加,携锶离子光交联海藻酸盐水凝胶溶胀率呈逐渐降低的趋势,弹性模量呈逐渐升高的趋势;④随着引入锶离子浓度的提高,MC3T3-E1细胞在携锶离子光交联海藻酸盐水凝胶表面的早期黏附率呈递增趋势,细胞伸展越来越好;⑤结果表明,在光交联海藻酸盐水凝胶中引入锶离子,可提高其机械性能,促进细胞的黏附伸展.

It can get better effect to perform tooth demineralization for tough tissue in multitudinous oral disease during clinical therapy. Demineralization of tooth is needed in many simulated experiments in vitro. Demineralization is not only essential measure of tooth treatment, but also the progress of part of tooth diseases. This paper summarized the current methods of demineralization for tooth hard tissue.

目的:评价离体牙梯度浓度脱矿后的理化性能,为牙支架材料的临床应用提供依据.方法:收集健康正畸减数牙56颗及牙槽骨标本4例,将牙齿标本随机分为单一浓度脱矿A组(阴性对照组),梯度浓度脱矿B、C、D组(实验组),未脱矿E组(阴性对照组),牙槽骨F组(阳性对照组).脱矿完成后通过分析天平测量质量变化、扫描电子显微镜(scanning electron microscope,SEM)观察表面形貌变化、能谱仪(EDX)测量组成元素含量变化、显微硬度仪测量不同层厚硬度变化.结果:离体牙脱矿后质量变化率为30％ ～65％,无机物含量减少,范围为0.82％ ～38.05％;根据脱矿环境不同牙本质小管不同程度暴露,且显微硬度降低,与未脱矿牙差异明显(P<0.05),单一浓度脱矿后表面与中心硬度差异明显,梯度浓度脱矿后从表面到中心硬度呈梯度变化;C2、D3组与牙槽骨显微硬度及矿物质含量无明显差异.结论:梯度浓度脱矿法可制备出力学相容性优良、理化性能优化的牙槽嵴增高材料,但其临床疗效有待进一步研究.

目的 对预防腮腺肿瘤切除术后并发症的Meta分析进行汇总评价.方法 检索PubMed、Cochrane Library、CNKI和WanFang Data关于腮腺肿瘤切除术后并发症预防的Meta分析,检索时间为建库到2018年9月12日.按照纳入标准筛选文献、提取资料,采用AMSTAR量表评价纳入研究的质量.结果 共纳入24个研究,探讨13种干预措施对预防腮腺肿瘤切除术后并发症的效果.AMSTAR质量评价结果显示,3个高质量研究,16个中等质量研究,5个低质量研究.结论 本研究所涉及的干预措施对Frey综合征、涎瘘/积液、面部畸形预防有一定的效果,对术后复发、感染无明显效果,对面神经麻痹的疗效不确定;此外,仍然需实施严谨和规范的原始研究、直接比较Meta分析/系统评价或间接比较网状Meta分析,为临床提供更可靠、全面的证据.

Objective To compare the efficacy of the gradient demineralized teeth with different conditioning times to be used as autograft in alveolar augmentation. Methods 12 New Zealand rabbits were randomly divided into 4 groups (A to D), the maxillary incisors were fixed on the incisor distal of mandible by titanium nail after acid treatment with different conditioning time, mandible samples were taken for X-ray examination and hematoxylin-eosin staining at 3 months after surgery. Results 3 months after the operation, the boundary between bone and autografts were distinct in undecalcified teeth group (group D), the autografts were absorbed in the early stage in the group with long-term decalcifying time(group A), the autografts were replaced by new bone in the group with short-term decalcifying time (group B and C), and the speed of bone remodeling significantly increased with decalcifying time. Conclusion Grandient demineralized autogenous tooth can be used for alveolar augmentation, to some extent, the speed of bone remodeling significantly increased with decalcifying time.

目的:探讨不同浓度盐酸处理的梯度脱矿自体牙作为牙槽嵴增高材料与牙槽骨的结合情况.方法:3月龄雄性新西兰家兔18只,随机分为梯度脱矿自体牙组(A组),未脱矿自体牙组(B组)及自体胫骨组(C组),分别取自体牙及自体胫骨,经预处理后用钛钉固定在兔牙槽骨上,增加牙槽嵴高度,12周后处死动物,进行X线检查与HE染色.结果:术后12周,梯度脱矿自体牙片发生血管化,原移植物被新骨取代;未脱矿自体牙组未出现明显再吸收现象,与骨组织之间存在清晰界限;自体胫骨与牙槽骨发生骨整合,结合紧密,但供骨区出现术后感染.结论:经梯度脱矿处理的自体牙增高牙槽嵴具有自体骨组织移植相似效果.