Precise orchestration of cell fate determination underlies the success of scaffold-based skeletal regeneration. Despite extensive studies on mineralized parenchymal tissue rebuilding, regenerating and maintaining undifferentiated mesenchyme within calvarial bone remain very challenging with limited advances yet. Current knowledge has evidenced the indispensability of rebuilding suture mesenchymal stem cell niches to avoid severe brain or even systematic damage. But to date, the absence of promising therapeutic biomaterials/scaffolds remains. The reason lies in the shortage of fundamental knowledge and methodological evidence to understand the cellular fate regulations of scaffolds. To address these issues, in this study, we systematically investigated the cellular fate determinations and transcriptomic mechanisms by distinct types of commonly used calvarial scaffolds. Our data elucidated the natural processes without scaffold transplantation and demonstrated how different scaffolds altered in vivo cellular responses. A feasible scaffold, polylactic acid electrospinning membrane (PLA), was next identified to precisely control mesenchymal ingrowth and self-renewal to rebuild non-osteogenic suture-like tissue at the defect center, meanwhile supporting proper osteointegration with defect bony edges. Especially, transcriptome analysis and cellular mechanisms underlying the well-orchestrated cell fate determination of PLA were deciphered. This study for the first time cellularly decoded the fate regulations of scaffolds in suture-bony composite defect healing, offering clinicians potential choices for regenerating such complicated injuries.

细胞命运决定的精确协调是基于支架的骨骼再生成功的基础。尽管对矿化实质组织重建进行了广泛的研究，但颅骨内未分化间质的再生和维持仍然非常具有挑战性，且进展有限。目前的知识已经证明重建缝合间充质干细胞生态位对于避免严重的大脑甚至系统损伤是必不可少的。但迄今为止，仍然缺乏有前景的治疗性生物材料/支架。原因在于缺乏理解支架细胞命运调控的基础知识和方法论证据。为了解决这些问题，在本研究中，我们系统地研究了不同类型的常用颅骨支架的细胞命运决定和转录组机制。我们的数据阐明了无需支架移植的自然过程，并证明了不同支架如何改变体内细胞反应。接下来确定了一种可行的支架，即聚乳酸静电纺丝膜（PLA），可以精确控制间充质向内生长和自我更新，以重建缺损中心的非成骨缝合样组织，同时支持缺损骨边缘的适当骨整合。特别是，转录组分析和 PLA 精心策划的细胞命运决定背后的细胞机制被破译。这项研究首次从细胞角度解码了支架在缝合-骨复合缺损愈合中的命运调控，为临床医生再生此类复杂损伤提供了潜在的选择。