负载褪黑素的甲基丙烯酰明胶微球延缓髓核退变

Melatonin-loaded gelatin methacryloyl microspheres delay nucleus pulposus degeneration

背景:髓核退变是椎间盘退变的重要病理环节,褪黑素可通过抗炎抗氧化等途径对细胞产生保护作用,然而褪黑素对髓核作用的研究较少,目前各种生物支架的出现为药物与材料结合的研究提供了新思路。目的:探究褪黑素是否可以通过减轻氧化应激损伤来改善髓核的代谢状态,以及负载褪黑素的甲基丙烯酰明胶(gelatin methacryloyl,GelMA)微球在体内对椎间盘退变的影响。方法:在体外,将褪黑素与成胶前的GelMA微球溶液结合,通过微流控技术将GelMA水凝胶制成微球,与髓核细胞共培养,利用CCK-8法检测细胞增殖活力,扫描电镜下观察微球的表面形态,用紫外分光光度计检测药物释放的速率,随后用白细胞介素1β诱导髓核退变,给予治疗后采用qRT-PCR检测基质合成基因聚集蛋白多糖、Ⅱ型胶原蛋白α1及基质降解基因基质金属蛋白酶13、ADAMTS5的表达水平。在大鼠体内采用针刺方法诱导髓核退变,随后分别注入GelMA和GelMA@MT微球,6周后取标本进行组织染色,显微镜下观察组织形态的变化,对其进行组织学分析及评分。结果与结论:①电子扫描显微镜下观察制得的GelMA和GelMA@MT微球,褪黑素的结合并没有改变微球的形态与外貌;药物释放实验显示40 d后药物释放达到80%左右;②CCK-8结果显示,GelMA与GelMA@MT微球均无明显细胞毒性,且对髓核细胞增殖起促进作用;③qRTPCR结果揭示,GelMA@MT微球可使白细胞介素1β环境下聚集蛋白多糖和Ⅱ型胶原蛋白α1的表达分别提高42.1%和27.1%,使基质金属蛋白酶13和ADAMTS5的表达分别降低70.7%和109.3%;④白细胞介素1β+GelMA@MT组活性氧水平显著低于白细胞介素1β组和白细胞介素1β+GelMA组;⑤切片组织学染色可见,负载了褪黑素的GelMA微球在体内可显著延缓椎间盘退变;⑥提示将褪黑素与GelMA水凝胶结合制成的GelMA@MT微球在体外显示出良好的细胞相容性,在体内外显著延缓髓核退变。

BACKGROUND:Nucleus pulposus degeneration is an important pathological link of intervertebral disc degeneration.Melatonin has a protective effect on cells through anti-inflammatory and antioxidant pathways,but the effect of melatonin on the nucleus pulposus has been less studied.At present,the emergence of various biological scaffolders provides a new idea for the study of drug-material combinations.OBJECTIVE:To explore whether melatonin can improve the metabolic state of the nucleus pulposus by reducing oxidative stress damage as well as the effect of gelatin methacryloyl(GelMA)microspheres loaded with melatonin on intervertebral disc degeneration in vivo.METHODS:In vitro,melatonin was combined with GelMA solution,and GelMA hydrogel was prepared into microspheres by microfluidic technology to coculture with nucleus pulposus cells.The cell proliferation activity was detected by cell counting kit-8 assay,the surface morphology of the microspheres was observed under scanning electron microscopy,and the rate of drug release was detected by ultraviolet spectrophotometer.Then,interleukin-1βwas used to induce degeneration of the nucleus pulposus.After treatment,the expression levels of aggrecan,type II collagenα1,matrix metalloproteinase 13 and a disintegrin and metalloproteinase with thrombospondin motifs-5(ADAMTS5)in the nucleus pulposus were detected by qRT-PCR.In vivo,nucleus pulposus degeneration was induced by puncture.Subsequently,GelMA and GelMA@MT microspheres were injected.After 6 weeks,the specimens were taken for tissue staining,and the changes in tissue morphology were observed under the microscope for histological analysis and scoring.RESULTS AND CONCLUSION:(1)When the GelMA and GelMA@MT microspheres were observed under electron scanning microscope,melatonin binding did not change the morphology and external appearance of the microspheres.Drug release experiments showed that the drug release reached about 80%after 40 days.(2)Cell counting kit-8 assay results showed that both GelMA and GelMA@MT microspheres had no obvious cytotoxicity and promoted the proliferation of nucleus pulposus cells.(3)qRT-PCR results revealed that GelMA@MT microspheres increased the expression of aggrecan and type I collagenα1 in the interleukin 1βenvironment by 42.1%and 27.1%,respectively,and decreased the expression of matrix metalloproteinase 13 and ADAMTS5 by 70.7%and 109.3%,respectively.(4)The level of reactive oxygen species was significantly lower in the interleukin 1β+GelMA@MT group than in the interleukin 1βand interleukin 1β+GelMA groups.(5)Histological staining of the sections showed that melatonin-loaded GelMA microspheres significantly delayed disc degeneration in vivo.(6)These findings indicate that GelMA@MT microspheres made by combining melatonin with GelMA hydrogel have good cytocompatibility in vitro and significantly delay nucleus pulposus degeneration in vitro and in vivo.