Towards Controlling the Local Bone Tissue Remodeling-Multifunctional Injectable Composites for Osteoporosis Treatment

Thermosensitive hydrogel doped with osteoconductive fillers for the treatment of periodontitis periapicalis chronica: from synthesis to clinical trial

Herein, a chitosan-based thermosensitive hydrogel (CH) containing hydroxyapatite (HAp), poly(lactic acid) (PLDLLA) or their mixture is proposed as an innovative, biomimetic composition with antimicrobial and bone-forming properties for guided bone regeneration. The modified hydrogels were synthesized and characterized to verify their suitability for the treatment of periodontitis periapicalis chronica. Compared to the unmodified hydrogel, both CH_HAp and CH_PLDLLA revealed improved mechanical properties, as evidenced by rotational rheology. FTIR analysis proved that no chemical interplay existed between the components. All the tested samples displayed no cytotoxicity against osteoblast-like cell culture and confirmed antimicrobial features, both crucial from an application perspective. Radiation sterilization dosage was tailored for the tested samples to maintain sterility for a minimum of 8 weeks of storage and limit crosslinking of the samples. Finally, the hydrogel was used in a clinical trial to treat a patient with chronic inflammation of periapical tissues in teeth 26 and 27. The medical procedure proved the safety, nontoxicity, non-allergenicity, and, most importantly, bone-forming properties of the hydrogel formulation. The kinetics of new bone formation was analyzed in-depth using graphical cross-sections of anatomical structures obtained from pre- and post-operative CBCT scans.

Photocrosslinked gelatin/chondroitin sulfate/chitosan-based composites with tunable multifunctionality for bone tissue regeneration

Novel hydrogel-based multifunctional systems prepared utilizing photocrosslinking and freeze-drying processes (PhotoCross/Freeze-dried) dedicated for bone tissue regeneration are presented. Fabricated materials, composed of methacrylated gelatin, chitosan, and chondroitin sulfate, possess interesting features including bioactivity, biocompatibility, as well as antibacterial activity. Importantly, their degradation and swellability might be easily tuned by playing with the biopolymeric content in the photocrosllinked systems. To broaden the potential application and deliver the therapeutic features, mesoporous silica particles functionalized with methacrylate moieties decorated with hydroxyapatite and loaded with the antiosteoporotic drug, alendronate, (MSP-MA-HAp-ALN) were dispersed within the biopolymeric sol and photocrosslinked. It was demonstrated that the obtained composites are characterized by a significantly extended degradation time, ensuring optimal conditions for balancing hybrids removal with the deposition of fresh bone. We have shown that attachment of MSP-MA-HAp-ALN to the polymeric matrix minimizes the initial burst effect and provides a prolonged release of ALN (up to 22 days). Moreover, the biological evaluation in vitro suggested the capability of the resulted systems to promote bone remodeling. Developed materials might potentially serve as scaffolds that after implantation will fill up bone defects of various origin (osteoporosis, tumour resection, accidents) providing the favourable conditions for bone regeneration and supporting the infections' treatment.

Innovative Vancomycin-Loaded Hydrogel-Based Systems - New Opportunities for the Antibiotic Therapy

Purpose

Surgical site infections pose a significant challenge for medical services. Systemic antibiotics may be insufficient in preventing bacterial biofilm development. With the local administration of antibiotics, it is easier to minimize possible complications, achieve drugs' higher concentration at the injured site, as well as provide their more sustained release. Therefore, the main objective of the proposed herein studies was the fabrication and characterization of innovative hydrogel-based composites for local vancomycin (VAN) therapy.

Methods

Presented systems are composed of ionically gelled chitosan particles loaded with vancomycin, embedded into biomimetic collagen/chitosan/hyaluronic acid-based hydrogels crosslinked with genipin and freeze-dried to serve in a flake/disc-like form. VAN-loaded carriers were characterized for their size, stability, and encapsulation efficiency (EE) using dynamic light scattering technique, zeta potential measurements, and UV-Vis spectroscopy, respectively. The synthesized composites were tested in terms of their physicochemical and biological features.

Results

Spherical structures with sizes of about 200 nm and encapsulation efficiencies reaching values of approximately 60% were obtained. It was found that the resulting particles exhibit stability over time. The antibacterial activity of the developed materials against Staphylococcus aureus was established. Moreover, in vitro cell culture study revealed that the surfaces of all prepared systems are biocompatible as they supported the proliferation and adhesion of the model MG-63 cells. In addition, we have demonstrated significantly prolonged VAN release while minimizing the initial burst effect for the composites compared to bare nanoparticles and verified their desired physicochemical features during swellability, and degradation experiments.

Conclusion

It is expected that the developed herein system will enable direct delivery of the antibiotic at an exposed to infections surgical site, providing drugs sustained release and thus will reduce the risk of systemic toxicity. This strategy would both inhibit biofilm formation and accelerate the healing process.

Study of Injectable Hydrogel Based on ALN/nHA Promoting Osteogenesis and Inhibiting Osteoclasts in Osteoporotic Bone Defects Repair

Osteoporotic bone defects cannot withstand surgery with more significant trauma due to bone fragility, while systemic drug therapy has formidable adverse effects. Consequently, the present study introduces an innovatively devised injectable double-crosslinked hydrogel, as a potential therapeutic avenue for addressing varied shapes of osteoporotic bone defects via a minimally invasive approach. The injectable hydrogel is formed by the formation of Schiff base bonds between oxidized sodium alginate (OSA) and carboxymethyl chitosan, and the polymerization of gelatin methacrylate by UV light crosslinking. Additionally, alendronate sodium (ALN) is loaded into the hydrogel through Schiff base formation with OSA, and nanohydroxyapatite (nHA) is incorporated into the hydrogel via blending. The hydrogel demonstrates excellent injectability, and the nHA improves the mechanical properties of hydrogel and can promote bone formation. In addition, the hydrogel can sustain the release of ALN, which has the effect of inhibiting osteoclasts. Cell studies indicate that the hydrogel can promote the differentiation of osteoblasts and inhibit the activity of osteoclast, so as to obtain better osteogenic effect. Therefore, the injectable hydrogel can be used to repair osteoporotic bone defects through a minimally invasive, simple treatment modality.

In vitro/ex vivo evaluation of multifunctional collagen/chitosan/hyaluronic acid hydrogel-based alendronate delivery systems

Injectable hydrogel-based materials have emerged as promising alendronate (ALN) delivery systems for the treatment of osteoporosis. However, their intrinsic permeability limits the sustained delivery of small-molecule drugs. In response to this challenge, we present the multifunctional hybrids composed of mesoporous silica particles decorated with hydroxyapatite and loaded with alendronate (MSP-NH2-HAp-ALN), which are immobilized in collagen/chitosan/hyaluronic acid-based hydrogel. We have mainly focused on the biological in vitro/ex vivo evaluation of developed composites. It was found that the extracts released from tested systems do not exhibit hemolytic properties and are safe for blood elements and the human liver cell model. The resulting materials create an environment conducive to differentiating human bone marrow mesenchymal stem cells and reduce the viability of osteoclast precursors (RAW 264.7). Importantly, even the system with the lowest concentration of ALN caused a substantial cytotoxic effect on RAW 264.7 cells; their viability decreased to 20 % and 10 % of control on 3 and 7 day of culture. Additionally, prolonged ALN release (up to 20 days) with minimized burst release was observed, while material features (wettability, swellability, degradation, mechanical properties) depended on MSP-NH2-HAp-ALN content. The obtained data indicate that developed composites establish a high-potential formulation for safe and effective osteoporosis therapy.

Study on a co-hybrid nano-hydroxyapatite with lignin derivatives and alendronate and the reinforce effect for poly(lactide-co-glycolide)

A novel co-hybrid nano-apatite (n-HA) by introducing lignin derivatives (LDs) and alendronate (ALE) was designed to reinforce poly(lactide-co-glycolide) (PLGA). The effect of different addition methods and contents of LDs, lignin derivatives sorts of lignosulfonate (LS), alkali lignin (AL) and carboxymethyl lignin (CML), and the addition order of ALE on the dispersion of hybrid n-HA, and reinforce effective for PLGA were investigated by FTIR, XRD, TEM, TGA, XPS, N2 adsorption/desorption, zeta potential, dispersion experiments, universal testing machine, SEM, DSC and POM. The results showed that the addition order could regulate the growth of n-HA crystal planes by binding with Ca2+, and co-hybrid HA by LDs and ALE possessed better dispersion owing to the synergistic effect. Moreover, 10 wt% LS-ALE-n-HA displayed the best reinforce effect, and the tensile strength of composite was 24.43 % higher than that of PLGA, even 15 wt% LS-ALE-n-HA was added, it still exhibited reinforce effect for PLGA. In vitro soaking in simulated body fluid (SBF) results indicated that LS-ALE-n-HA delayed tensile strength reduce of PLGA and promoted bone-like apatite deposition. The cell proliferation results demonstrated that the hybrid n-HA by the introduction of ALE endowed PLGA with better cell adhesion and proliferation.