Bez Maxim, Sheyn Dmitriy, Tawackoli Wafa, Avalos Pablo, Shapiro Galina, Giaconi Joseph C, Da Xiaoyu, David Shiran Ben, Gavrity Jayne, Awad Hani A, Bae Hyun W, Ley Eric J, Kremen Thomas J, Gazit Zulma, Ferrara Katherine W, Pelled Gadi, Gazit Dan
Skeletal Biotech Laboratory, Hadassah Faculty of Dental Medicine, The Hebrew University of Jerusalem, Ein Kerem, Jerusalem 91120, Israel.
Department of Surgery, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA.
Sci Transl Med. 2017 May 17;9(390). doi: 10.1126/scitranslmed.aal3128.
More than 2 million bone-grafting procedures are performed each year using autografts or allografts. However, both options carry disadvantages, and there remains a clear medical need for the development of new therapies for massive bone loss and fracture nonunions. We hypothesized that localized ultrasound-mediated, microbubble-enhanced therapeutic gene delivery to endogenous stem cells would induce efficient bone regeneration and fracture repair. To test this hypothesis, we surgically created a critical-sized bone fracture in the tibiae of Yucatán mini-pigs, a clinically relevant large animal model. A collagen scaffold was implanted in the fracture to facilitate recruitment of endogenous mesenchymal stem/progenitor cells (MSCs) into the fracture site. Two weeks later, transcutaneous ultrasound-mediated reporter gene delivery successfully transfected 40% of cells at the fracture site, and flow cytometry showed that 80% of the transfected cells expressed MSC markers. Human (-) plasmid DNA was delivered using ultrasound in the same animal model, leading to transient expression and secretion of BMP-6 localized to the fracture area. Micro-computed tomography and biomechanical analyses showed that ultrasound-mediated gene delivery led to complete radiographic and functional fracture healing in all animals 6 weeks after treatment, whereas nonunion was evident in control animals. Collectively, these findings demonstrate that ultrasound-mediated gene delivery to endogenous mesenchymal progenitor cells can effectively treat nonhealing bone fractures in large animals, thereby addressing a major orthopedic unmet need and offering new possibilities for clinical translation.
每年使用自体骨移植或异体骨移植进行的骨移植手术超过200万例。然而，这两种选择都有缺点，对于大规模骨质流失和骨折不愈合的新疗法的开发，仍然存在明确的医学需求。我们假设，局部超声介导的、微泡增强的治疗性基因传递至内源性干细胞将诱导有效的骨再生和骨折修复。为了验证这一假设，我们通过手术在尤卡坦小型猪（一种临床相关的大型动物模型）的胫骨上制造了一个临界尺寸的骨折。在骨折处植入胶原支架，以促进内源性间充质干/祖细胞（MSC）募集到骨折部位。两周后，经皮超声介导的报告基因传递成功转染了骨折部位40%的细胞，流式细胞术显示80%的转染细胞表达MSC标志物。在同一动物模型中使用超声递送人（-）质粒DNA，导致BMP-6在骨折区域的瞬时表达和分泌。微型计算机断层扫描和生物力学分析表明，超声介导的基因传递导致所有动物在治疗后6周实现完全的影像学和功能性骨折愈合，而对照动物则明显出现骨折不愈合。总体而言，这些发现表明，超声介导的基因传递至内源性间充质祖细胞可以有效治疗大型动物的骨不连骨折，从而满足了骨科领域一个未被满足的主要需求，并为临床转化提供了新的可能性。
