Feng Ganjun, Zhang Zhanpeng, Dang Ming, Rambhia Kunal J, Ma Peter X
Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI, 48109, USA.
Macromolecular Science and Engineering Center, University of Michigan, Ann Arbor, MI, 48109, USA.
Biomaterials. 2020 Oct;256:120213. doi: 10.1016/j.biomaterials.2020.120213. Epub 2020 Jun 21.
Lower back pain is mainly caused by intervertebral disc degeneration, in which calcification is frequently involved. Here novel nanofibrous spongy microspheres (NF-SMS) are used to carry rabbit bone marrow mesenchymal stromal cells (MSCs) to regenerate nucleus pulposus tissues. NF-SMS are shown to significantly enhance the MSC seeding, proliferation and differentiation over control microcarriers. Furthermore, a hyperbranched polymer (HP) with negligible cytotoxicity and high microRNA (miRNAs) binding affinity is synthesized. The HP can complex with anti-miR-199a and self-assemble into "double shell" polyplexes which are able to achieve high transfection efficiency into MSCs. A double-emulsion technique is used to encapsulate these polyplexes in biodegradable nanospheres (NS) to enable sustained anti-miR-199 delivery. Our results demonstrate that MSC/HP-anti-miR-199a/NS/NF-SMS constructs can promote the nucleus pulposus (NP) phenotype and resist calcification in vitro and in a subcutaneous environment. Furthermore, injection of MSC/HP-anti-miR-199a/NS/NF-SMS can stay in place, produce functional extracellular matrix, maintain disc height and prevent intervertebral disc (IVD) calcification in a rabbit lumbar degeneration model.
下背痛主要由椎间盘退变引起，其中钙化常与之相关。在此，新型纳米纤维海绵微球（NF-SMS）被用于携带兔骨髓间充质基质细胞（MSC）以再生髓核组织。结果表明，与对照微载体相比，NF-SMS能显著增强MSC的接种、增殖和分化。此外，合成了一种细胞毒性可忽略不计且对微小RNA（miRNA）具有高结合亲和力的超支化聚合物（HP）。该HP可与抗miR-199a复合并自组装成“双壳”多聚体，能够实现对MSC的高效转染。采用双乳液技术将这些多聚体封装在可生物降解的纳米球（NS）中，以实现抗miR-199的持续递送。我们的结果表明，MSC/HP-抗miR-199a/NS/NF-SMS构建体在体外和皮下环境中均可促进髓核（NP）表型并抵抗钙化。此外，在兔腰椎退变模型中，注射MSC/HP-抗miR-199a/NS/NF-SMS可原位留存、产生功能性细胞外基质、维持椎间盘高度并防止椎间盘（IVD）钙化。
