Akermanite used as an alkaline biodegradable implants for the treatment of osteoporotic bone defect

In osteoporosis scenario, tissue response to implants is greatly impaired by the deteriorated boneregeneration microenvironment. In the present study, a Mg-containing akermanite (Ak) ceramic wasemployed for the treatment of osteoporotic bone defect, based on the hypothesis that both beneficialions (e.g. Mg^2+ ect.) released by the implants and the weak alkaline microenvironment pH (μe-pH) itcreated may play distinct roles in recovering the abnormal bone regeneration by stimulating osteoblasticanabolic effects. The performance of Ak, b-tricalcium phosphate (β-TCP) and Hardystone (Har) in healinga 3 mm bone defect on the ovariectomized (OVX) osteoporotic rat model was evaluated. Our resultsindicated that, there's more new bone formed in Ak group than in β-TCP or Har group at week 9. Theinitial me-pHs of Ak were significantly higher than that of the β-TCP and Blank group, and this weakalkaline condition was maintained till at least 9 weeks post-surgery. Increased osteoblastic activity whichwas indicated by higher osteoid secretion was observed in Ak group at week 4 to week 9. An intermediatelayer which was rich in phosphorus minerals and bound directly to the new forming bone wasdeveloped on the surface of Ak. In a summary, our study demonstrates that Ak exhibits a superior boneregenerative performance under osteoporosis condition, and might be a promising candidate for thetreatment of osteoporotic bone defect and fracture.

A novel akermanite/poly (lactic-co-glycolic acid) porous composite scaffold fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process

Desirable scaffolds for tissue engineering should be biodegradable carriers to supply suitablemicroenvironments mimicked the extracellular matrices for desired cellular interactions and to providesupports for the formation of new tissues. In this work, a kind of slightly soluble bioactiveceramic akermanite (AKT) powders were aboratively selected and introduced in the PLGA matrix,a novel L-lactide modified AKT/poly (lactic-co-glycolic acid) (m-AKT/PLGA) composite scaffold wasfabricated via a solvent casting-particulate leaching method improved by solvent self-proliferatingprocess. The effects of m-AKT contents on properties of composite scaffolds and on MC3T3-E1 cellularbehaviors in vitro have been primarily investigated. The fabricated scaffolds exhibited threedimensionalporous networks, in which homogenously distributed cavities in size of 300–400 lmwere interconnected by some smaller holes in a size of 100–200 lm. Meanwhile, the mechanicalstructure of scaffolds was reinforced by the introduction of m-AKT. Moreover, alkaline ionic productsreleased by m-AKT could neutralize the acidic degradation products of PLGA, and the apatitemineralizationability of scaffolds could be largely improved. More valuably, significant promotionson adhesion, proliferation, and differentiation of MC3T3-E1 have been observed, which implied thecalcium, magnesium and especially silidous ions released sustainably from composite scaffoldscould regulate the behaviors of osteogenesis-related cells.

Magnesium-containing bioceramics stimulate exosomal miR-196a-5p secretion to promote senescent osteogenesis through targeting Hoxa7/MAPK signaling axis

Stem cell senescence is characterized by progressive functional dysfunction and secretory phenotypic changes including decreased proliferation,dysfunction of osteogenic and angiogenic differentiation,increased secretion of the senescence-associated secretory phenotype(SASP),which bring difficulties for bone repair.Rescuing or delaying senescence of aged bone marrow mesenchymal stem cells(O-BMSCs)was considered as effective strategy for bone regeneration in aging microenvironment.Magnesium(Mg)ion released from bioceramics was reported to facilitate bone regeneration via enhancing osteogenesis and alleviating senescence.In this study,Akermanite biocreamics(Akt)containing Mg ion as a model was demonstrated to promote osteogenesis and angiogenesis effects of O-BMSCs by activating the MAPK signaling pathway in vitro.Moreover,the enhanced osteogenesis effects might be attributed to enhanced Mg-containing Akt-mediated exosomal miR-196a-5p cargo targeting Hoxa7 and activation of MAPK signaling pathway.Furthermore,the in vivo study confirmed that 3D-printed porous Mg-containing Akt scaffolds effectively increased bone regeneration in cranial defects of aged rats.The current results indicated that the exosomal-miR-196a-5p/Hoxa7/MAPK signaling axis might be the potential mechanism underlying Akt-mediated osteogenesis.The exosome-meditaed therapy stimulated by the released Mg ion contained in Akt biocreamics or other biomaterials might serve as a candidate strategy for bone repair in aged individuals.

Upconversion luminescence Ca-Mg-Si bioactive glasses synthesized using the containerless processing technique

In this study,a series of Er^3+/Yb^3+co-doped Ca-Mg-Si glasses were prepared via the containerless processing.Phase composition and luminescent properties of the prepared materials were investigated through XRD and spectrometry,and bioactivity,biocompatibility and cytotoxicity were evaluated.The XRD patterns indicated that akermanite(AKT)ceramic powders were completely transformed into the glassy phase(AKT-G,EYA)through the containerless processing,which exhibit upconversion luminescence,and the luminescence intensity increased with the increase of the doping amount of Er^3+ and Yb^3+.High amount of Yb^3+doping and existence of Ca^2+in glasses resulted in more intensive red-light emission.The SEM observation,combined with EDS analysis,and cell culture experiments showed that the as-prepared glasses were nontoxic,biocompatible and bioactive.All these results demonstrated that the containerless processing is a facile method for preparing homogeneous luminescent bioactive glasses.Furthermore,this luminescent Ca-Mg-Si glasses may be used as bone implant materials to study the in vivo distribution of degradation products of bone implants,which may be of great significance for the development and clinical application of new bone grafting materials.