Evaluating the osteoimmunomodulatory properties of micro-arc oxidized titanium surface at two different biological stages using an optimized in vitro cell culture strategy

Gallium-doped thermochemically treated titanium reduces osteoclastogenesis and improves osteodifferentiation

Excessive bone resorption is one of the main causes of bone homeostasis alterations, resulting in an imbalance in the natural remodeling cycle. This imbalance can cause diseases such as osteoporosis, or it can be exacerbated in bone cancer processes. In such cases, there is an increased risk of fractures requiring a prosthesis. In the present study, a titanium implant subjected to gallium (Ga)-doped thermochemical treatment was evaluated as a strategy to reduce bone resorption and improve osteodifferentiation. The suitability of the material to reduce bone resorption was proven by inducing macrophages (RAW 264.7) to differentiate to osteoclasts on Ga-containing surfaces. In addition, the behavior of human mesenchymal stem cells (hMSCs) was studied in terms of cell adhesion, morphology, proliferation, and differentiation. The results proved that the Ga-containing calcium titanate layer is capable of inhibiting osteoclastogenesis, hypothetically by inducing ferroptosis. Furthermore, Ga-containing surfaces promote the differentiation of hMSCs into osteoblasts. Therefore, Ga-containing calcium titanate may be a promising strategy for patients with fractures resulting from an excessive bone resorption disease.

Translating Material Science into Bone Regenerative Medicine Applications: State-of-The Art Methods and Protocols

In the last 20 years, bone regenerative research has experienced exponential growth thanks to the discovery of new nanomaterials and improved manufacturing technologies that have emerged in the biomedical field. This revolution demands standardization of methods employed for biomaterials characterization in order to achieve comparable, interoperable, and reproducible results. The exploited methods for characterization span from biophysics and biochemical techniques, including microscopy and spectroscopy, functional assays for biological properties, and molecular profiling. This review aims to provide scholars with a rapid handbook collecting multidisciplinary methods for bone substitute R&D and validation, getting sources from an up-to-date and comprehensive examination of the scientific landscape.

Modulation of T Cell Responses by Fucoidan to Inhibit Osteogenesis

Fucoidan has sparked considerable interest in biomedical applications because of its inherent (bio)physicochemical characteristics, particularly immunomodulatory effects on macrophages, neutrophils, and natural killer cells. However, the effect of fucoidan on T cells and the following regulatory interaction on cellular function has not been reported. In this work, the effect of sterile fucoidan on the T-cell response and the subsequent modulation of osteogenesis is investigated. The physicochemical features of fucoidan treated by high-temperature autoclave sterilization are characterized by UV–visible spectroscopy, X-ray diffraction, Fourier transform infrared and nuclear magnetic resonance analysis. It is demonstrated that high-temperature autoclave treatment resulted in fucoidan depolymerization, with no change in its key bioactive groups. Further, sterile fucoidan promotes T cells proliferation and the proportion of differentiated T cells decreases with increasing concentration of fucoidan. In addition, the supernatant of T cells co-cultured with fucoidan greatly suppresses the osteogenic differentiation of MC3T3-E1 by downregulating the formation of alkaline phosphatase and calcium nodule compared with fucoidan. Therefore, our work offers new insight into the fucoidan-mediated T cell and osteoblast interplay.

Sequential activation of M1 and M2 phenotypes in macrophages by Mg degradation from Ti-Mg alloy for enhanced osteogenesis

BACKGROUND

Even though the modulatory effects of Magnisum (Mg) and its alloys on bone-healing cells have been widely investigated during the last two decades, relatively limited attention has been paid on their inflammation-modulatory properties. Understanding the activation process of macrophages in response to the dynamic degradation process of Mg as well as the relationship between macrophage phenotypes and their osteogenic potential is critical for the design and development of advanced Mg-based or Mg-incorporated biomaterials.

METHODS

In this work, a Ti-0.625 Mg (wt.%) alloy fabricated by mechanical alloying (MA) and subsequent spark plasma sintering (SPS) was employed as a material model to explore the inflammatory response and osteogenic performance in vitro and in vivo by taking pure Ti as the control. The data analysis was performed following Student's t-test.

RESULTS

The results revealed that the macrophages grown on the Ti-0.625 Mg alloy underwent sequential activation of M1 and M2 phenotypes during a culture period of 5 days. The initially increased environmental pH (~ 8.03) was responsible for the activation of M1 macrophages, while accumulated Mg²⁺ within cells contributed to the lateral M2 phenotype activation. Both M1 and M2 macrophages promoted osteoblast-like SaOS-2 cell maturation. In vivo experiment further showed the better anti-inflammatory response, regenerative potentiality and thinner fibrous tissue layer for the Ti-0.625 Mg alloy than pure Ti.

CONCLUSION

The results highlighted the roles of Mg degradation in the Ti-0.625 Mg alloy on the sequential activation of macrophage phenotypes and the importance of modulating M1-to-M2 transition in macrophage phenotypes for the design and development of inflammation-modulatory biomaterials.

Irreversible Electroporation Plus Anti-PD-1 Antibody versus Irreversible Electroporation Alone for Patients with Locally Advanced Pancreatic Cancer

Background

Irreversible electroporation (IRE) is shown to not only improve the prognosis of patients with locally advanced pancreatic cancer (LAPC) but also activate the immune system. Considering the immune-activating function of IRE, IRE may enhance the effect of immune checkpoint inhibitors in the treatment of LAPC. We aimed to compare the effect and safety of IRE combined with toripalimab versus IRE alone for LAPC.

Methods

We retrospectively collected data from LAPC patients treated with IRE plus toripalimab (240mg, 7 days after IRE) or IRE alone at Sun Yat‑sen University Cancer Center. Overall and progression-free survival and treatment-related adverse events were evaluated and compared.

Results

From August 2015 to June 2020, a total of 85 patients were collected and analyzed in this study: 70 in the IRE group and 15 in the IRE plus toripalimab group. The IRE plus toripalimab group showed longer OS [44.33 months (95% CI 17.39–71.27) versus 23.37 months (95% CI 21.20–25.54), P=0.010] and PFS [27.5 months (95% CI not reached) versus 10.6 months (95% CI 7.79–13.42), P=0.036], compared with IRE group. There were no treatment-related deaths in all patients of this study. Although pancreatic fistula, biliary fistula, abscess, vomiting and gastroparesis were a little more common in IRE plus toripalimab group, no significant differences in the rates of all adverse events between these two groups were observed.

Conclusion

IRE plus toripalimab had acceptable toxic effects and might improve survival in LAPC compared with IRE alone.

The response of macrophages and their osteogenic potential modulated by micro/nano-structured Ti surfaces

Current understanding on the interactions between micro/nano-structured Ti surfaces and macrophages is still limited. In this work, TiO₂ nano-structures were introduced onto acid-etched Ti surfaces by alkali-heat treatment, ion exchange and subsequent heat treatment. By adjusting the concentration of NaOH during alkali-heat treatment, nano-flakes, nano-flakes mixed with nano-wires or nano-wires could formed on acid-etched Ti surfaces. The micro- and micro/nano-structured Ti surfaces possessed similar surface chemical and phase compositions. In vitro results indicate that the morphology of macrophages was highly dependent on the morphological features of nano-structures. Nano-flakes and nano-wires were favorable to induce the formation of lamellipodia and filopodia, respectively. Compared to micro-structured Ti surface, micro/nano-structured Ti surfaces polarized macrophages to their M2 phenotype and enhanced the gene expressions of osteogenic growth factors in macrophages. The M2 polarized macrophages promoted the maturation of osteoblasts. Compared to that with nano-flakes or nano-wires, the surface with mixed features of nano-flakes and nano-wires exhibited stronger anti-inflammatory and osteo-immunomodulatory effects. The findings presented in the current work suggest that introducing micro/nano-topographies onto Ti-based implant surfaces is a promising strategy to modulate the inflammatory response and mediate osteogenesis.

Hierarchically hybrid biocoatings on Ti implants for enhanced antibacterial activity and osteogenesis

Titanium (Ti) is widely applied as bone-anchoring implants in dental and orthopedic applications owing to its superior mechanical characteristics, high corrosion resistance, and excellent biocompatibility. Nevertheless, Ti-based implants with the deficiencies of insufficient osteoinduction and associated infections can result in implant failure, which significantly limits its applications in some cases. In this work, hierarchically hybrid biocoatings on Ti implants are developed by gradual incorporation of polydopamine (PDA), ZnO nanoparticles (nZnO), and chitosan (CS)/nanocrystal hydroxyapatite (nHA) via oxidative self-polymerization, nanoparticle deposition, solvent casting and evaporation methods for enhancing their antibacterial activity and osteogenesis. The modification of PDA on porous reticular Ti substrates greatly reduces the surface roughness, wettability, protein adsorption, and provides high adhesion to the deposited nZnO. Further, incorporating nZnO on PDA-coated Ti surfaces affects the surface structure and wettability, significantly inhibits the growth of both Staphylococcus aureus and Escherichia coli. Moreover, the CS/nHA-doped coating on the nZnO-modified Ti surfaces remarkably improves cytocompatibility and enhances the osteogenic differentiation of MC3T3-E1 cells by upregulating the protein expression of alkaline phosphatase. This work offers a promising alternative for developing Ti implants with long-lifetime bioactivity to achieve strong antibacterial ability and enhanced bone formation for potential dental/orthopedic applications.

Identification of Circulating Biomarkers and Construction of a Prognostic Signature for Survival Prediction in Locally Advanced Pancreatic Cancer After Irreversible Electroporation

Background

Irreversible electroporation (IRE) is a novel treatment for locally advanced pancreatic cancer (LAPC), but the predictive factors, based on cytokines and immunocytes of survival, are still lacking. This study aimed to establish a risk model based on cytokines and immunocytes for LAPC patients undergoing IRE treatment.

Patients and Methods

Peripheral blood samples were obtained from 31 LAPC patients and 8 healthy control subjects before IRE. The phenotypes of lymphocytes were analyzed by flow cytometry, and the cytokines were evaluated with Luminex microarray assay. Least absolute shrinkage and selection operator (LASSO) and Cox regression were applied to assess the prognostic factors for overall survival (OS) and progression-free survival (PFS). A receiver operating characteristic (ROC) curve and a concordance index (C-index) were used to compare the abilities to predict survival rates.

Results

The relationship between multiple cytokines and clinical factors was evaluated and their prognostic value was compared. The five best predictors for OS and PFS, including CA19-9, CD3⁺CD4⁺ T cells, CD3⁺CD8⁺ T cells, IL-17A, and TNF-α were selected and incorporated into a new immune panel. A risk model based on this immune panel was established and exhibited significantly higher values of C-indexes and AUC for OS and PFS prediction as compared with tumor marker score and TNM stage system.

Conclusion

We presented a risk model based on a microarray assay of cytokines and lymphocytes for LAPC patients after receiving IRE treatment for the first time. The established risk model showed relatively good performance in survival prediction and was able to facilitate tailed patient management in clinical practice.

The State of the Art and Prospects for Osteoimmunomodulatory Biomaterials

The critical role of the immune system in host defense against foreign bodies and pathogens has been long recognized. With the introduction of a new field of research called osteoimmunology, the crosstalk between the immune and bone-forming cells has been studied more thoroughly, leading to the conclusion that the two systems are intimately connected through various cytokines, signaling molecules, transcription factors and receptors. The host immune reaction triggered by biomaterial implantation determines the in vivo fate of the implant, either in new bone formation or in fibrous tissue encapsulation. The traditional biomaterial design consisted in fabricating inert biomaterials capable of stimulating osteogenesis; however, inconsistencies between the in vitro and in vivo results were reported. This led to a shift in the development of biomaterials towards implants with osteoimmunomodulatory properties. By endowing the orthopedic biomaterials with favorable osteoimmunomodulatory properties, a desired immune response can be triggered in order to obtain a proper bone regeneration process. In this context, various approaches, such as the modification of chemical/structural characteristics or the incorporation of bioactive molecules, have been employed in order to modulate the crosstalk with the immune cells. The current review provides an overview of recent developments in such applied strategies.