Repurposing sarecycline for osteoinductive therapies: an in vitro and ex vivo assessment.

INTRODUCTION: Tetracyclines (TCs) embrace a class of broad-spectrum antibiotics with unrelated effects at sub-antimicrobial levels, including an effective anti-inflammatory activity and stimulation of osteogenesis, allowing their repurposing for different clinical applications. Recently, sarecycline (SA)-a new-generation molecule with a narrower antimicrobial spectrum-was clinically approved due to its anti-inflammatory profile and reduced adverse effects verified with prolonged use. Notwithstanding, little is known about its osteogenic potential, previously verified for early generation TCs. MATERIALS AND METHODS: Accordingly, the present study is focused on the assessment of the response of human bone marrow-derived mesenchymal stromal cells (hBMSCs) to a concentration range of SA, addressing the metabolic activity, morphology and osteoblastic differentiation capability, further detailing the modulation of Wnt, Hedgehog, and Notch signaling pathways. In addition, an ex vivo organotypic bone development system was established in the presence of SA and characterized by microtomographic and histochemical analysis. RESULTS: hBMSCs cultured with SA presented a significantly increased metabolic activity compared to control, with an indistinguishable cell morphology. Moreover, RUNX2 expression was upregulated 2.5-fold, and ALP expression was increased around sevenfold in the presence of SA. Further, GLI2 expression was significantly upregulated, while HEY1 and HNF1A were downregulated, substantiating Hedgehog and Notch signaling pathways' modulation. The ex vivo model developed in the presence of SA presented a significantly enhanced collagen deposition, extended migration areas of osteogenesis, and an increased bone mineral content, substantiating an increased osteogenic development. CONCLUSION: Summarizing, SA is a promising candidate for drug repurposing within therapies envisaging the enhancement of bone healing/regeneration.

Assessment of the Bone Healing Process Mediated by Periosteum-Derived Mesenchymal Stem Cells' Secretome and a Xenogenic Bioceramic-An In Vivo Study in the Rabbit Critical Size Calvarial Defect Model.

The mesenchymal stem cell (MSC) secretome has been considered an innovative therapeutic biological approach, able to modulate cellular crosstalk and functionality for enhanced tissue repair and regeneration. This study aims to evaluate the functionality of the secretome isolated from periosteum-derived MSCs, from either basal or osteogenic-induced conditions, in the healing of a critical size calvarial bone defect in the rabbit model. A bioceramic xenograft was used as the vehicle for secretome delivery, and the biological response to the established biocomposite system was assessed by clinical, histological, histomorphometric, and microtomographic analysis. A comparative analysis revealed that the osteogenic-induced secretome presented an increased diversity of proteins, with emphasis on those related to osteogenesis. Microtomographic and histological morphometric analysis revealed that bioceramic xenografts implanted with secretomes enhanced the new bone formation process, with the osteogenic-induced secretome inducing the highest bone tissue formation. The application of the MSC secretome, particularly from osteogenic-induced populations, may be regarded as an effective therapeutic approach to enhance bone tissue healing and regeneration.

Engineering a multifunctional 3D-printed PLA-collagen-minocycline-nanoHydroxyapatite scaffold with combined antimicrobial and osteogenic effects for bone regeneration.

3D-printing and additive manufacturing can be powerful techniques to design customized structures and produce synthetic bone grafts with multifunctional effects suitable for bone repair. In our work we aimed the development of novel multifunctionalized 3D printed poly(lactic acid) (PLA) scaffolds with bioinspired surface coatings able to reduce bacterial biofilm formation while favoring human bone marrow-derived mesenchymal stem cells (hMSCs) activity. For that purpose, 3D printing was used to prepare PLA scaffolds that were further multifunctionalized with collagen (Col), minocycline (MH) and bioinspired citrate- hydroxyapatite nanoparticles (cHA). PLA-Col-MH-cHA scaffolds provide a closer structural support approximation to native bone architecture with uniform macroporous, adequate wettability and an excellent compressive strength. The addition of MH resulted in an adequate antibiotic release profile that by being compatible with local drug delivery therapy was translated into antibacterial activities against Staphylococcus aureus, a main pathogen associated to bone-related infections. Subsequently, the hMSCs response to these scaffolds revealed that the incorporation of cHA significantly stimulated the adhesion, proliferation and osteogenesis-related gene expression (RUNX2, OCN and OPN) of hMSCs. Furthermore, the association of a bioinspired material (cHA) with the antibiotic MH resulted in a combined effect of an enhanced osteogenic activity. These findings, together with the antibiofilm activity depicted strengthen the appropriateness of this 3D-printed PLA-Col-MH-cHA scaffold for future use in bone repair. By targeting bone repair while mitigating the typical infections associated to bone implants, our 3D scaffolds deliver an integrated strategy with the combined effects further envisaging an increase in the success rate of bone-implanted devices.

Assessment of the external load of amateur soccer players during four consecutive training microcycles in relation to the external load during the official match

Aim: The aim of this study was to assess the external load of amateur male players during 4 consecutive training microcycles (M) at the beginning of the in-season according to the training session in absolute external load demands and in relation to the competition demands. Methods: Regional-level players (n = 10; age, 20.8 ± 1.7 years; height, 175.5 ± 3.8 cm; body mass, 69.7 ± 2.9 kg; soccer experience, 13.2 ± 2.5 years) were monitored using GPS devices during training sessions and matches. The external load variables measured were: duration (min); total distance covered (TD); distance covered at high-speed (HID, 14.4-19.8 km/h); distance covered at sprinting (SPD; >19.8 km/h); and distance covered in high intensity acceleration (ACD; >2.5 m/s2) and deceleration (DECD; <-2.5 m/s2). Results: The results indicated that the external load variables (time, HID, SPD, ACD, and DECD) were similar between the four microcycles. Greater (p<0.01) time, TD, HID and SPD were observed in match day (MD)-2 compared to MD+1, MD-3, and MD-1. Aside from training duration, all external loads variables (TD, HID, SPD, ACD, and DECD) were lower during training sessions compared to official matches (p<0.05). Conclusion: Amateur soccer players present relative stable external training loads across competitive microcycles, with the peak load observed two days before the official match. Besides this, the match constitutes the highest load during a typical competitive microcycle in this cohort of players.(AU)