Osteogenic and Immunomodulatory Effects of Novel Bone Adhesives for Use in Sternal Fixation
Notice bibliographique
Résumé
Median sternotomy is a procedure that involves cutting open the sternum longitudinally and is the most common method to access to the heart and surrounding valves for cardiothoracic surgery. Following the procedure, closure of the sternum with stainless steel wires remains the current standard of care. Despite the widespread use of this closure technique, post-operative complications pose life-threatening consequences. Sternal separation occurs in up to 8% of cases and results in a 40% mortality rate. Glass polyalkenoate cements (GPCs) are adhesives that have the potential to augment the mechanical union of the two sternal halves by wire cerclage. This dissertation relates to the biocompatibility testing of proprietary GPCs for use in sternal fixation and repair. The GPCs investigated are based on the same novel strontium and zinc containing bioactive glass (mole fraction: SiO2:0.48, ZnO:0.36, CaO:0.12, SrO:0.04). Two GPCs were formulated (GPCA and GPCB) and their effect on osteogenic differentiation and immunomodulation was assessed in vitro. Bone mineralization, collagen formation and alkaline phosphatase activity were found to be significantly elevated in response to GPCA’s dissolution products. However, all three osteogenic markers were inhibited when cultured with GPCA in direct and indirect culture set-ups. GPCB also reduced these markers in comparison to control cultures, but performed significantly better than GPCA. For immune studies, GPC dissolution products and GPC particles were tested for their ability to affect the secretion of cytokines peripheral blood mononuclear cells (PBMCs). Additionally, the size, shape and concentration of fragmented GPC particles were characterized. The results showed that GPCA ionic products had an anti-inflammatory effect, where they significantly reduced the secretion of TNF-α secreted from PBMCs stimulated with LPS. Conversely, the particles released from GPCA significantly stimulated the secretion TNF-α and IL-6 compared to control cultures. Overall, GPC B significantly outperformed GPC A and was selected for animal testing, where it was implanted subcutaneously in rats for 6 and 12 weeks. Polymethyl-methacrylate (PMMA) bone cement was used as a baseline control, and histological assessment revealed no adverse tissue reaction in response to GPCB. Additionally, relative expression of pro-inflammatory and osteogenic genes was assessed in the tissue surrounding implants and revealed no significant differences in expression between the GPC and control. It is concluded that GPCs based on the novel Sr/Zn glass system have varied biocompatibility which depends on the cement composition. Based on the obtained results, the formulated adhesive may offer optimal fixation for patients undergoing cardiac surgery and reduce post-operative complications.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».