延迟的萎缩性愈合和不愈合所带来的挑战是骨质疏松性骨折治疗中的巨大障碍。H型血管生成和成骨过程是骨再生过程中的关键机制。值得注意的是,低氧条件下脂肪干细胞(ADSC)外泌体的预处理因其增加外泌体分泌和功能的潜力而备受关注.在目前的调查中,我们着手全面阐明骨质疏松性骨再生环境中hypo-ADSC-Exos的潜在机制。我们的发现揭示了hypo-ADSC-Exos拥有一个卓越的miRNA,即,miR-21-5p,成为血管生成效应的主要协调者。通过体外实验,我们证明了hypo-ADSC-Exos刺激增殖的能力,迁移,以及通过miR-21-5p介导人脐静脉内皮细胞(HUVECs)的血管生成潜力。miR-21-5p的抑制有效地减弱了由hypo-ADSC-Exos介导的促血管生成作用。机械上,我们的研究表明,来自hypo-ADSCs的外泌体miR-21-5p通过靶向HUVECs内的sprouly1(SPRY1)发挥其调控作用,从而促进PI3K/AKT信号通路的激活。值得注意的是,发现HUVEC中SPRY1的敲低可增强PI3K/AKT的激活,同时,HUVEC增殖,迁移,和血管生成。我们研究的高潮阶段涉及令人信服的体内演示,其中验证了装载有hypo-ADSC-Exos的GelMA可显著增强局部H型血管生成和伴随的骨再生。这种增强明确归因于SPRY1的外泌体调节。总之,我们的调查为hypo-ADSC-Exos在骨质疏松性骨折治疗中的潜在效用提供了一个开创性的观点.
The challenges posed by delayed atrophic healing and nonunion stand as formidable obstacles in osteoporotic fracture treatment. The processes of type H angiogenesis and osteogenesis emerge as pivotal mechanisms during bone regeneration. Notably, the preconditioning of adipose-derived stem cell (ADSC) exosomes under hypoxic conditions has garnered attention for its potential to augment the secretion and functionality of these exosomes. In the present investigation, we embarked upon a comprehensive elucidation of the underlying mechanisms of hypo-ADSC-Exos within the milieu of osteoporotic bone regeneration. Our findings revealed that hypo-ADSC-Exos harboured a preeminent miRNA, namely, miR-21-5p, which emerged as the principal orchestrator of angiogenic effects. Through in vitro experiments, we demonstrated the capacity of hypo-ADSC-Exos to stimulate the proliferation, migration, and angiogenic potential of human umbilical vein endothelial cells (HUVECs) via the mediation of miR-21-5p. The inhibition of miR-21-5p effectively attenuated the proangiogenic effects mediated by hypo-ADSC-Exos. Mechanistically, our investigation revealed that exosomal miR-21-5p emanating from hypo-ADSCs exerts its regulatory influence by targeting sprouly1 (SPRY1) within HUVECs, thereby facilitating the activation of the PI3K/AKT signalling pathway. Notably, knockdown of SPRY1 in HUVECs was found to potentiate PI3K/AKT activation and, concomitantly, HUVEC proliferation, migration, and angiogenesis. The culminating stage of our study involved a compelling in vivo demonstration wherein GelMA loaded with hypo-ADSC-Exos was validated to substantially enhance local type H angiogenesis and concomitant bone regeneration. This enhancement was unequivocally attributed to the exosomal modulation of SPRY1. In summary, our investigation offers a pioneering perspective on the potential utility of hypo-ADSC-Exos as readily available for osteoporotic fracture treatment.