Advancements in 3D bioprinting are revolutionizing bone tissue engineering by enabling patient-specific, biomimetic scaffolds with stem cells to promote efficient bone regeneration and repair. Integrating bioceramic or decellularized bone-based bioinks provides osteoinduces cues to enhance bone regeneration but achieving native tissue-level cell density remains a challenge. While 3D bioprinting strategies increasingly allow for spatial control of scaffold composition and cell placement, current embedded bioprinting techniques are limited by the rheological constraints of shear-thinning microgel supports, restricting material selection and structural fidelity. To overcome this, we developed a novel embedded bioprinting platform using photocurable viscous hydrogels as layer-by-layer support matrices.
1, 2 Here, we expand this platform by incorporating osteoinductive microparticles—decellularized human bone allograft or tricalcium phosphate (TCP)—within methacrylated hyaluronic acid (MeHA) support hydrogels to fabricate 3D constructs of aggregated human mesenchymal stem cells (hMSCs) to assess their impact on osteogenesis. The support gels are printed and partially photocrosslinked in sequence before the fully crosslinking at the end, allowing stable cell deposition while maintaining mechanical integrity and bioactivity. Composite MeHA matrices containing human bone allograft or tricalcium phosphate (TCP) microparticles were assessed for rheological, mechanical, and then osteoinductive performance. Incorporation of microparticles did not significantly affect viscosity, crosslinking behavior, or compressive modulus, preserving the mechanical robustness of the constructs. High cell viability (>95%) and consistent strand morphology were maintained across all printing conditions, confirming the method’s capacity to preserve both cell integrity and geometric fidelity. Importantly, bone allograft particles markedly enhanced osteogenic differentiation of hMSCs, with elevated alkaline phosphatase activity and calcium deposition. Osteogenesis occurred even in basal media in a dose-dependent manner, highlighting the intrinsic bioactivity of the bone matrix. These findings establish the utility of integrating embedded bioprinting with osteoinductive microcomposites to fabricate dense, functional bone constructs. The ability to promote osteogenesis without exogenous growth factors supports its potential for spatial control of chondrogenesis and osteogenesis within same tissue constructs.
- M Guvendiren, S Ji, A Abaci US Patent 11,806,444 (2023) and 12,121,632 (2024).
- A Abaci, M Guvendiren, Biofabrication, 2024, 16:035027.
