Sustained adenosine release:Revealing its impact on osteogenic signalling pathways of human mesenchymal stromal cells

Non-healing fractures,a global health concern arising from trauma,osteoporosis,and tumours,can lead to severe disabilities.Adenosine,integral to cellular energy metabolism,gains prominence in bone regeneration via adeno-sine A2 B receptor activation.This study introduces a controlled-release system for localized adenosine delivery,fostering human mesenchymal stromal cell(hMSC)differentiation into functional bone cells.The study investi-gates how the ratio of lactic acid to glycolic acid in microparticles can influence adenosine release and explores the downstream effects on gene expression and metabolic profiles of osteogenic differentiation in hMSCs cultured in growth and osteoinductive media.Insights into adenosine-modulated signalling pathways during MSC differenti-ation,with osteogenic factors,provide a comprehensive understanding of the pathways involved.Analysing gene expression and metabolic profiles unravels adenosine’s regulatory mechanisms in MSC differentiation.Sustained adenosine release from microparticles induces mineralization,synergizing with osteogenic media supplements,showcasing the potential of adenosine for treating critical bone defects and metabolic disorders.This study high-lights the efficacy of a polymeric microparticle-based delivery system,offering novel strategies for bone repair.Unveiling adenosine’s roles and associated signalling pathways advances our comprehension of molecular mech-anisms steering bone regeneration,propelling innovative biomaterial,combined with metabolites,approaches for clinical use.

In vivo analysis of hybrid hydrogels containing dual growth factor combinations,and skeletal stem cells under mechanical stimulation for bone repair

Bone tissue engineering requires a combination of materials,cells,growth factors and mechanical cues to recapitulate bone formation.In this study we evaluated hybrid hydrogels for minimally invasive bone formation by combining biomaterials with skeletal stem cells and staged release of growth factors together with mechanotransduction.Hybrid hydrogels consisting of alginate and decellularized,demineralised bone extracellular matrix(ALG/ECM)were seeded with Stro-1t human bone marrow stromal cells(HBMSCs).Dual combinations of growth factors within staged-release polylactic-co-glycolic acid(PLGA)microparticles were added to hydrogels to mimic,in part,the signalling events in bone regeneration:VEGF,TGF-β_(3),PTHrP(fast release),or BMP-2,vitamin D_(3)(slow release).Mechanotransduction was initiated using magnetic fields to remotely actuate superparamagnetic nanoparticles(MNP)targeted to TREK1 ion channels.Hybrid hydrogels were implanted subcutaneously within mice for 28 days,and evaluated for bone formation using micro-CT and histology.Control hydrogels lacking HBMSCs,growth factors,or MNP became mineralised,and neither growth factors,HBMSCs,nor mechanotransduction increased bone formation.However,structural differences in the newly-formed bone were influenced by growth factors.Slow release of BMP-2 induced thick bone trabeculae and PTHrP or VitD_(3)increased bone formation.However,fast-release of TGF-β_(3)and VEGF resulted in thin trabeculae.Mechanotransduction reversed the trabecular thinning and increased collagen deposition with PTHrP and VitD_(3).Our findings demonstrate the potential of hybrid ALG/ECM hydrogel–cell–growth factor constructs to repair bone in combination with mechanotransduction for fine-tuning bone structure.This approach may form a minimally invasive reparative strategy for bone tissue engineering applications.