Bioactive coatings with anti-osteoclast therapeutic agents for bone implants: Enhanced compliance and prolonged implant life

The use of therapeutic agents that inhibit bone resorption is crucial to prolong implant life, delay revision surgery, and reduce the burden on the healthcare system. These therapeutic agents include bisphosphonates, various nucleic acids, statins, proteins, and protein complexes. Their use in systemic treatment has several drawbacks, such as side effects and insufficient efficacy in terms of concentration, which can be eliminated by local treatment. This review focuses on the incorporation of osteoclast inhibitors (antiresorptive agents) into bioactive coatings for bone implants. The ability of bioactive coatings as systems for local delivery of antiresorptive agents to achieve optimal loading of the bioactive coating and its release is described in detail. Various parameters such as the suitable concentrations, release times, and the effects of the antiresorptive agents on nearby cells or bone tissue are discussed. However, further research is needed to support the optimization of the implant, as this will enable subsequent personalized design of the coating in terms of the design and selection of the coating material, the choice of an antiresorptive agent and its amount in the coating. In addition, therapeutic agents that have not yet been incorporated into bioactive coatings but appear promising are also mentioned. From this work, it can be concluded that therapeutic agents contribute to the biocompatibility of the bioactive coating by enhancing its beneficial properties.

Pamidronate-Encapsulated Electrospun Polycaprolactone-Based Composite Scaffolds for Osteoporotic Bone Defect Repair

Bone fractures associated with osteoporosis are a major concern all over the world especially among the elderly population and postmenopausal women. Bisphosphonates (BPs) are widely used clinically for both treatment and prevention of osteoporosis despite their poor oral bioavailability and undesired side effects. Local delivery of BPs from polymeric scaffolds can improve the efficacy and overcome the undesirable side effects associated with oral bisphosphonate therapy. The aim of the present study is to explore the effectiveness of pamidronate (PDS) encapsulated electrospun polycaprolactone/polycaprolactone-polyethyleneglycol-polycaprolactone/nanohydroxyapatite (PCH) scaffolds in healing critical-size calvarial defects in an osteoporotic rat animal model. Prior to implantation studies, the effect of PDS on the fiber architecture, mechanical properties, and in vitro degradation behavior was evaluated. The in vitro release of PDS from PCH scaffolds in phosphate buffer saline (PBS) at 37 °C was monitored for a period of 21 days. An osteoporotic animal model was successfully developed in Wistar rats by bilateral ovariectomy. Results of micro CT (computed tomography) and blood serum analysis confirmed the osteoporotic model induction in rats. Critical-size calvarial defects of 8 mm size were created in osteoporotic rats, and the in vivo osteogenic efficacy of PCH-PDS scaffolds was evaluated by micro CT, histology, and histomorphometry. Micro CT analysis showed improved osseous tissue integration with the use of PDS-loaded PCH scaffolds after 12 week post implantation. Histology, density measurement using micro CT, and histomorphometry further substantiate that PCH-PDS scaffolds have the potential to be used for the repair of osteoporotic bone defects. Our findings revealed that incorporation of PDS onto PCH scaffolds provides a promising biomaterial that could be used for regenerating osteoporosis-related fractures.

Antithrombogenic properties of Tulbaghia violacea–loaded polycaprolactone nanofibers

A broad range of polymers have been utilized for the development of blood-contacting implantable medical devices; however, their rate of failure has raised the need for developing more hemocompatible biomaterial surfaces. In this study, a novel scaffold based on polycaprolactone incorporated with 10% and 15% (w/w) Tulbaghia violacea plant extracts were fabricated using electrospinning technique. The fabricated scaffolds were then treated with T. violacea aqueous plant extracts (100 and 1000 µg/mL) to investigate their use as interfaces for blood-contacting implants. The 10% Tvio scaffold produced the lowest mean fibre diameter (193 ± 30 nm), whereas the 15% Tvio scaffold produces the highest mean fibre diameter (538 ± 236 nm) when compared with the control polycaprolactone (275 ± 61 nm) scaffold. The number of adhered platelets was directly linked to fibre diameter and concentration of plant extract in such a way that the lowest fibre diameter scaffold (10% Tvio) inhibited platelet adhesion, whereas more platelets adhered to the scaffold with the highest fibre diameter (15% Tvio scaffolds). There was also an increase in platelet adhesion as the concentration of T. violacea was increased from 100 to 1000 µg/mL for all designed scaffolds. The improved blood compatibility demonstrated by the 10% Tvio scaffold suggests that the plant possesses antithrombogenic properties, particularly at lower concentrations.