Extracellular matrix-inspired multi-morphology microspheres harness osteogenic-prone stem cells to recruit and
Huixin Lv1, Yihan Wang2, Jingxia Chen2
1Department of Prosthodontics, Peking University School and Hospital of Stomatology, 100081 Beijing, China; National Center for Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and National Health Commission Key Laboratory of Digital Technology of Stomatology, 100081 Beijing, China; Institute of Advanced Clinical Medicine, Peking University, 100191 Beijing, China.
Objectives:
The limited proportion and age-related decline in proliferative capacity of skeletal stem cells within jawbone tissue hinder efficient bone regeneration. Enhancing osteogenesis through stem cell recruitment and phenotypic modulation via intercellular communication remains an underexplored strategy. We hypothesized that osteogenic-prone stem cells can recruit adjacent osteogenic-weak cells and promote their proliferation and osteogenic differentiation. Biomimetic scaffolds mimicking an extracellular matrix (ECM) microenvironment favorable to osteogenic-prone stem cells may amplify this intercellular cascade.
Methods:
Based on our previous findings of two osteogenically heterogeneous stem cell populations with intercellular communication potential, we designed biomimetic mineralized (methacrylated gelatin)-fibrinogen crosslinked hydrogel microspheres (bmGFMs) via microemulsion and photocrosslinking, guided by the gene signatures of the osteogenic-prone stem cell subtype. These microspheres supported multidirectional cell growth and were used to construct a 3D culture system in which distinct stem cell populations were loaded separately under contact or non-contact conditions. The proliferative, migratory, and osteogenic capacities of the cells were examined using RNA-seq, qRT-PCR, western blot, immunofluorescence, subcutaneous ectopic transplantation, etc. In vivo study was conducted in rabbits undergoing bilateral bone augmentation in the maxillary posterior region, and regeneration outcomes were assessed via micro-CT, H&E staining, immunofluorescence, etc. RESULTS: The bmGFMs provided physicochemical and mechanical cues that preferentially recruited osteogenic-prone stem cells for colonization and osteogenesis via FAK/PKC/PI3K/Akt signaling pathway. Enhanced interstitial fluid infiltration facilitated paracrine signaling (e.g., SDF-1) from these primed cells, recruiting nearby osteogenic-weak populations and inducing their osteogenic conversion, thereby expanding osteogenic source. In vivo, bmGFMs guided spatiotemporal bone formation, achieving high-density intramembranous ossification through dual-cell synergy.
Conclusion:
Harnessing endogenous stem cell cooperation to enrich osteogenic sources offers a promising strategy for jawbone regeneration. Developing biomimetic materials tailored to genetic profiles of resident osteogenic-prone stem cells to sequentially enhance stemness maintenance and osteogenic differentiation provides a potent collaborative approach for bone tissue engineering.
