Fabrication of 3D-printed scaffolds loaded with gallium acetylacetonate for potential application in osteoclastic bone resorption.

We recently reported the potential of a new gallium compound, gallium acetylacetonate (GaAcAc) in combating osteoclastic bone resorption through inhibition of osteoclast differentiation and function. Herein, we focused on 3D-printed polylactic acid scaffolds that were loaded with GaAcAc and investigated the impact of scaffold pretreatment with polydopamine (PDA) or sodium hydroxide (NaOH). We observed a remarkable increase in scaffold hydrophilicity with PDA or NaOH pretreatment while biocompatibility and in vitro degradation were not affected. NaOH-pretreated scaffolds showed the highest amount of GaAcAc loading when compared to other scaffolds (p < 0.05). NaOH-pretreated scaffolds with GaAcAc loading showed effective reduction of osteoclast counts and size. The trend was supported by suppression of key osteoclast differentiation markers such as NFAT2, c-Fos, TRAF6, & TRAP. All GaAcAc-loaded scaffolds, regardless of surface pretreatment, were effective in inhibiting osteoclast function as evidenced by reduction in the number of resorptive pits in bovine cortical bone slices (p < 0.01). The suppression of osteoclast function according to the type of scaffold followed the ranking: GaAcAc loading without surface pretreatment > GaAcAc loading with NaOH pretreatment > GaAcAc loading with PDA pretreatment. Additional studies will be needed to fully elucidate the impact of surface pretreatment on the efficacy and safety of GaAcAc-loaded 3D-printed scaffolds.

Efficacy assessment of methylcellulose-based thermoresponsive hydrogels loaded with gallium acetylacetonate in osteoclastic bone resorption.

Homeostatic imbalance involving progressive stimulation of osteoclast (OC) differentiation and function will lead to an increased risk of fragility fractures. In this regard, we investigated gallium acetylacetonate (GaAcAc) as a possible treatment for osteoclastic bone resorption. Further, the extent to which suitable delivery systems can enhance the therapeutic potential of GaAcAc was evaluated. GaAcAc solution (10-50 µg/mL) suppressed OC differentiation using murine monocytic RAW 264.7 or hematopoietic stem cells. Methylcellulose-based hydrogels were fabricated and characterized based on biocompatibility with bone cells, GaAcAc loading, and thermoresponsive behavior using storage (G') and loss (G″) moduli parameters. Compared to GaAcAc solution, hydrogels loaded with GaAcAc (GaMH) were more effective in suppressing OC differentiation and function. The number and extent of bone resorption pits from ex vivo studies were markedly reduced with GaMH treatment. Mechanistic assessment of GaMH efficacy showed superiority, compared to GaAcAc solution, in downregulating the expression of key markers involved in mediating OC differentiation (such as NFAT2, cFos, TRAF6, and TRAP) as well as in bone resorption by OCs (cathepsin K or CTSK). Additional studies (in vitro and in vivo) suggested that the performance of GaMH could be ascribed to controlled release of GaAcAc and the ability to achieve prolonged bio-retention after injection in BALB/c mice, which plausibly maximized the therapeutic impact of GaAcAc. Overall, the work demonstrated, for the first time, the therapeutic efficacy of GaAcAc and the therapeutic potential of GaMH delivery systems in osteoclastic bone resorption.

Polymeric micelles of suberoylanilide hydroxamic acid to enhance the anticancer potential in vitro and in vivo.

AIM: To improve the bioavailability and anticancer potential of suberoylanilide hydroxamic acid (SAHA) by developing a drug-loaded polymeric nanomicellar system. METHODS: SAHA-loaded Poly(ethylene glycol)-block-poly(caprolactone) (PEG-PCL) micelles were developed, and physico-chemically characterized. In vitro cellular uptake, viability and apoptosis-inducing ability of the SAHA-PEG-PCL micelles were investigated. In vivo anticancer activity was evaluated in C57BL/6 mice-bearing tumor. RESULTS: The SAHA-PEG-PCL micelles had optimum size (∼130 nm) with an entrapment efficiency of approximately 67%. The SAHA-PEG-PCL induced stronger cell cycle arrest in G2/M phase leading to higher rate of apoptosis compared to free SAHA. SAHA-PEG-PCL demonstrated significant tumor suppression compared to free SAHA in vivo. CONCLUSION: The physicochemical properties and the antitumor efficacy of SAHA were improved by encapsulating in polymeric micelles.

Cholesterol-conjugated poly(D, L-lactide)-based micelles as a nanocarrier system for effective delivery of curcumin in cancer therapy.

Polymeric micelles have been widely explored preclinically as suitable delivery systems for poorly soluble chemotherapeutic drugs in cancer therapy. The present study reported the development of cholesterol (Ch)-conjugated poly(D,L-Lactide) (PLA)-based polymeric micelles (mPEG-PLA-Ch) for effective encapsulation and delivery of curcumin (CUR) at the tumor site. Cholesterol conjugation dramatically affected the particle size and improved drug loading (DL) and encapsulation efficiency (EE). mPEG-PLA-Ch-CUR showed bigger hydrodynamic diameter (104.6 ± 2.1 nm, and 169.3 ± 1.52 nm for mPEG-PLA and mPEG-PLA-Ch, respectively) due to increased size of the hydrophobic core. The newly developed polymer exhibited low critical micelles concentration (CMC) (25 µg/mL) which is close to lipid-based polymer, PEG-phosphatidyl ethanolamine (12.5 µg/mL) compared to mPEG-PLA (50 µg/mL). mPEG-PLA-Ch micelles exhibited relatively higher EE (93.74 ± 1.6%) and DL (11.86 ± 0.8%) compared to mPEG-PLA micelles (EE 91.89 ± 1.2% and DL 11.06 ± 0.8%). mPEG-PLA-Ch micelles were internalized by the cancer cells effectively and exhibited higher cytotoxicity compared to free CUR in both, murine melanoma (B16F10) and human breast cancer (MDA-MB-231) cells. mPEG-PLA-Ch exhibited satisfactory hemocompatibility indicating their potential for systemic application. Further, mPEG-PLA-Ch-CUR demonstrated higher rate of reduction of tumor volume in B16F10-xenografted tumor-bearing mice compared to free CUR. At the end of 22 days, the tumor reduced to 1.87-fold (627.72 ± 0.9 mm3 versus 1174.68 ± 1.64 mm3) compared to the treatment with free CUR. In conclusion, the experimental data in vitro and in vivo indicated that the newly developed CUR-mPEG-PLA-Ch micelles may have promising applications in solid tumors.