Transfection system of amino-functionalized calcium phosphate nanoparticles: in vitro efficacy, biodegradability, and immunogenicity study

Immunomodulatory Properties: The Accelerant of Hydroxyapatite-Based Materials for Bone Regeneration

The immunoinflammatory response is the prerequisite step for wound healing and tissue regeneration, and the immunomodulatory effects of biomaterials have attracted increasing attention. Hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂] (HAp), a common calcium phosphate ceramic, due to its structural and functional similarity to the inorganic constituent of natural bones, has been developed for different application purposes such as bone substitutes, tissue engineering scaffolds, and implant coatings. Recently, the interaction between HAp-based materials and the immune system (various immune cells), and the immunomodulatory effects of HAp-based materials on bone tissue regeneration have been explored extensively. Macrophages-mediated regenerative effect by HAp stimulation occupies the mainstream status of immunomodulatory strategies. The immunomodulation of HAp can be manipulated by tuning the physical, chemical, and biological cues such as surface functionalization (physical or chemical modifications), structural and textural characteristics (size, shape, and surface topography), and the incorporation of bioactive substances (cytokines, rare-earth elements, and bioactive ions). Therefore, HAp ceramic materials can contribute to bone regeneration by creating a favorable osteoimmune microenvironment, which would provide a more comprehensive theoretical basis for their further clinical applications. Considering the rapidly developed HAp-based materials as well as their excellent biological performances in the field of regenerative medicine, this review discusses the recent advances concerning the immunomodulatory methods for HAp-based biomaterials and their roles in bone tissue regeneration.

CaP-based anti-inflammatory HIF-1α siRNA-encapsulating nanoparticle for rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a common inflammatory disease and its treatment is largely limited by drug ineffectiveness or severe side effects. In RA progression, multiple signalling pathways, such as hypoxia-inducible factor (HIF)-1α, nuclear factor kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) pathways, act synergistically to maintain the inflammatory response. To downregulate HIF-1α, NF-κB, and MAPK expression, we proposed HIF-1α siRNA-loaded calcium phosphate nanoparticles encapsulated in apolipoprotein E3-reconstituted high-density lipoprotein (HIF-CaP-rHDL) for RA therapy. Here, we evaluated the potential of CaP-rHDL nanoparticles in RA therapy using a murine macrophage line (RAW 264.7) and a collagen-induced arthritis (CIA) mouse model. The CaP-rHDL nanoparticles showed significant anti-inflammatory effects along with HIF-1α knockdown and NF-κB and MAPK signalling pathway inhibition in lipopolysaccharide-activated macrophages. Moreover, they inhibited receptor activator of NF-κB ligand (RANKL)-induced osteoclast formation. In CIA mice, their intravenous administration resulted in high accumulation at the arthritic joint sites, and HIF-CaP-rHDL effectively suppressed inflammatory cytokine secretion and relieved bone erosion, cartilage damage, and osteoclastogenesis. Thus, HIF-CaP-rHDL demonstrated great potential in RA precision therapy by inhibiting multiple inflammatory signalling pathways.

Materials for Improving Immune Cell Transfection

Chimeric antigen receptor T cell (CAR-T) therapy holds great promise for preventing and treating deadly diseases such as cancer. However, it remains challenging to transfect and engineer primary immune cells for clinical cell manufacturing. Conventional tools using viral vectors and bulk electroporation suffer from low efficiency while posing risks like viral transgene integration and excessive biological perturbations. Emerging techniques using microfluidics, nanoparticles, and high-aspect-ratio nanostructures can overcome these challenges, and on top of that, provide universal and high-throughput cargo delivery. Herein, the strengths and limitations of traditional and emerging materials for immune cell transfection, and commercial development of these tools, are discussed. To enhance the characterization of transfection techniques and uptake by the clinical community, a list of in vitro and in vivo assays to perform, along with relevant protocols, is recommended. The overall aim, herein, is to motivate the development of novel materials to meet rising demand in transfection for clinical CAR-T cell manufacturing.

Polymer-Coated Hydroxyapatite Nanocarrier for Double-Stranded RNA Delivery

Conventional synthetic insecticides have limited success due to insect resistance and negative effects on off-target biota and the environment. Although RNA interference (RNAi) is a tool that is becoming more widely utilized in pest control products, naked dsRNA has limited success in most taxa. Nanocarriers have shown promising results in enhancing the efficacy of this tool. In this study, we used a layer-by-layer electrostatic assembly where we synthesized poly(acrylic acid) (PAA)-coated hydroxyapatite (HA) nanoparticles (PAA-HA NPs) as inorganic nanocarriers, which were then coated with a layer of a cationic poly(amino acid), 10 kDa poly-l-arginine (PLR₁₀), to allow for binding of a layer of negatively charged dsRNA. Binding of PLR₁₀-PAA-HA NPs to dsRNA was found to increase as the mass ratio of NPs to dsRNA increased. In vitro studies with transgenic SF9 cells (from Spodoptera frugiperda) expressing the firefly luciferase gene showed a significant gene silencing (35% decrease) at a 5:1 NP-to-dsRNA ratio, while naked dsRNA was ineffective at gene silencing. There was a significant concentration-response relationship in knockdown; however, cytotoxicity was observed at higher concentrations. Confocal microscopy studies showed that dsRNA from PLR₁₀-PAA-HA NPs was not localized within endosomes, while naked dsRNA appeared to be entrapped within the endosomes. Overall, polymer-functionalized HA nanocarriers enabled dsRNA to elicit gene knockdown in cells, whereas naked dsRNA was not effective in causing gene knockdown.

Biodegradable calcium phosphate nanoparticles for cancer therapy

Calcium phosphate is the inorganic mineral of hard tissues such as bone and teeth. Due to their similarities to the natural bone, calcium phosphates are highly biocompatible and biodegradable materials that have found numerous applications in dental and orthopedic implants and bone tissue engineering. In the form of nanoparticles, calcium phosphate nanoparticles (CaP's) can also be used as effective delivery vehicles to transfer therapeutic agents such as nucleic acids, drugs, proteins and enzymes into tumor cells. In addition, facile preparation and functionalization of CaP's, together with their inherent properties such as pH-dependent solubility provide advantages in delivery and release of these bioactive agents using CaP's as nanocarriers. In this review, the challenges and achievements in the intracellular delivery of these agents to tumor cells are discussed. Also, the most important issues in the design and potential applications of CaP-based biominerals are addressed with more focus on their biodegradability in tumor microenvironment.

Enhancement of bone mineral density and body mass in newborn chickens by in ovo injection of ionic-hydroxyapatite nanoparticles of bacterial origin

Using non-drug, non-surgical treatments for improving bone mineral diseases in newborn babies is an important topic for neonatologists. The present study introduces bacterial synthesized ionic nano-hydroxyapatite (Bio-HA) for the development of bone mineral density in the chicken embryo model. In vitro cytotoxicity analyses were demonstrated the optimal concentrations of Bio-HA compared to a chemically-synthesized hydroxyapatite (Ch-HA). Toxicity of Bio-HA on MCF-7 human cell lines was negligible at the concentrations less than 500 μg/mL whereas Ch-HA showed similar results at the concentrations less than 100 μg/mL. Therefore, concentrations at 50 μg/mL and 100 μg/mL were selected for in ovo injection of both materials into the fertilized eggs. The newly hatched chickens were sacrificed in order to monitor their serological factors, total body mass, bone mineral contents and bone mineral density. The results confirmed that Bio-HA increased the average body weight and bone mineral indices of chickens in comparison to the Ch-HA and negative controls (normal saline and intact groups). In view of the intact group, no liver or kidney damage occurred in the groups receiving Bio-HA which promises the effectiveness of these nanoparticles for the treatment of afterbirth bone mineral deficiency.

Small addition of Zn2+ in Ca2+@DNA results in elevated gene transfection by aminated PGMA-modified silicon nanowire arrays

Gene therapy, a promising and effective treatment, has ignited new hope in overcoming difficult-to-cure diseases. The key question in gene therapy is how to efficiently and safely deliver exogenous nucleic acids into the nuclei of target cells. To achieve stable, efficient and safe gene transfer and to ensure efficiency of gene transfer into cell nuclei, a zinc ion-assisted gene delivery nanosystem was proposed in the present study by loading a low concentration of Zn²⁺ in Ca²⁺@DNA nanoparticles on ethanolamine-functionalized poly(glycidyl methacrylate) (PGEA)-modified SiNWAs (Zn²⁺/Ca²⁺@DNA + SN-PGEA). The results showed that with the help of Zn ions, this composite nanosystem could promote more DNA in the cell nuclei and thus dramatically increased the transfection efficiency by as much as 7-fold. The nanosystem with 0.2 mM Zn²⁺, 100 mM Ca²⁺ and PGEA modification on SiNWAs displayed the highest transfection efficiency and good biocompatibility. This new composite nanosystem will have great potential in gene transfection for biomedical research.

Calcium-based biomaterials for diagnosis, treatment, and theranostics

Calcium-based biomaterials with good biosafety and bio-absorbability are promising for biomedical applications such as diagnosis, treatment, and theranostics.

Effects of engineered nanoparticles on the innate immune system

Engineered nanoparticles (NPs) have broad applications in industry and nanomedicine. When NPs enter the body, interactions with the immune system are unavoidable. The innate immune system, a non-specific first line of defense against potential threats to the host, immediately interacts with introduced NPs and generates complicated immune responses. Depending on their physicochemical properties, NPs can interact with cells and proteins to stimulate or suppress the innate immune response, and similarly activate or avoid the complement system. NPs size, shape, hydrophobicity and surface modification are the main factors that influence the interactions between NPs and the innate immune system. In this review, we will focus on recent reports about the relationship between the physicochemical properties of NPs and their innate immune response, and their applications in immunotherapy.

Bioadhesive Bacterial Microswimmers for Targeted Drug Delivery in the Urinary and Gastrointestinal Tracts

Bacteria-driven biohybrid microswimmers (bacteriabots), which integrate motile bacterial cells and functional synthetic cargo parts (e.g., microparticles encapsulating drug), are recently studied for targeted drug delivery. However, adhesion of such bacteriabots to the tissues on the site of a disease (which can increase the drug delivery efficiency) is not studied yet. Here, this paper proposes an approach to attach bacteriabots to certain types of epithelial cells (expressing mannose on the membrane), based on the affinity between lectin molecules on the tip of bacterial type I pili and mannose molecules on the epithelial cells. It is shown that the bacteria can anchor their cargo particles to mannose-functionalized surfaces and mannose-expressing cells (ATCC HTB-9) using the lectin-mannose bond. The attachment mechanism is confirmed by comparing the adhesion of bacteriabots fabricated from bacterial strains with or without type I pili to mannose-covered surfaces and cells. The proposed bioadhesive motile system can be further improved by expressing more specific adhesion moieties on the membrane of the bacteria.

Nanocaged platforms: modification, drug delivery and nanotoxicity. Opening synthetic cages to release the tiger

Nanocages (NCs) have emerged as a new class of drug-carriers, with a wide range of possibilities in multi-modality medical treatments and theranostics. Nanocages can overcome such limitations as high toxicity caused by anti-cancer chemotherapy or by the nanocarrier itself, due to their unique characteristics. These properties consist of: (1) a high loading-capacity (spacious interior); (2) a porous structure (analogous to openings between the bars of the cage); (3) enabling smart release (a key to unlock the cage); and (4) a low likelihood of unfavorable immune responses (the outside of the cage is safe). In this review, we cover different classes of NC structures such as virus-like particles (VLPs), protein NCs, DNA NCs, supramolecular nanosystems, hybrid metal-organic NCs, gold NCs, carbon-based NCs and silica NCs. Moreover, NC-assisted drug delivery including modification methods, drug immobilization, active targeting, and stimulus-responsive release mechanisms are discussed, highlighting the advantages, disadvantages and challenges. Finally, translation of NCs into clinical applications, and an up-to-date assessment of the nanotoxicology considerations of NCs are presented.

Calcium phosphate nanoparticles prepared from infusion fluids for stem cell transfection: process optimization and cytotoxicity analysis

The preparation of calcium phosphate nanoparticles from infusion fluids for gene delivery to stem cells and CHO-K1 cells is reported.

A biological method for in-situ synthesis of hydroxyapatite-coated magnetite nanoparticles using Enterobacter aerogenes: Characterization and acute toxicity assessments

Hydroxyapatite (HA)-coated magnetite nanoparticles (MNPs) are being widely investigated for various applications in medical engineering and wastewater treatment. In this work, the MNPs were thoroughly coated by bacterial synthesized HA nanoparticles during biomineralization process using Enterobacter aerogenes. The resulting bacterial-induced precipitate was then calcined at 600°C and investigated with respect to structural characteristics, particle size and magnetic strength by XRD, FT-IR, SEM, EDS, TEM and VSM analyses. The effects of MNPs and HA-coated MNPs (HA-MNPs) on the viability of human MCF-7 cell lines were also investigated via mitochondrial activity test (MTT) and lactate dehydrogenase (LDH) assays. The powder characterization results showed appropriate structural properties for HA-MNPs samples. The particles diameter size of the MNPs and HA-MNPs were in the range of 3-25nm and 20-80nm, respectively. The biologically-synthesized HA-MNPs formed a stable suspension in water while keeping their magnetic property. The saturation magnetization (Ms) of HA-MNPs was measured at ~10emug^-1 which was in good agreement with the structural composition of this sample. Finally, the results of the cell lines viability indicated that coating of toxic MNPs via biomineralization was a promising approach in order to synthesize bio-compatible magnetic nanoparticles with suitable physical and chemical structural characteristics. The toxicity level of MNPs was reduced by 10 fold when coated by bacterial-synthesized HA.

Efficient Transfection by Using PDMAEMA-Modified SiNWAs as a Platform for Ca(2+)-Dependent Gene Delivery

The major bottleneck for gene delivery lies in the lack of safe and efficient gene vectors and delivery systems. In order to develop a much safer and efficient transfection system, a novel strategy of combining traditional Ca(2+)-dependent transfection with cationic polymer poly(N,N-dimethylamino)ethyl methacrylate (PDMAEMA) modified silicon nanowire arrays (SiNWAs) was proposed in this work. Detailed studies were carried out on the effects of the PDMAEMA polymerization time, the Ca(2+) concentration, and the incubation time of Ca(2+)@DNA complex with PDMAEMA-modified SiNWAs (SN-PDM) on the gene transfection in the cells. The results demonstrated that the transfection efficiency of SN-PDM assisted traditional Ca(2+)-dependent transfection was significantly enhanced compared to those without any surface assistance, and SN-PDM with polymerization time 24 h exhibited the highest efficiency. Moreover, the optimal transfection efficiency was found at the system of a complex containing Ca(2+) (100 mM) and plasmid DNA (pDNA) incubated on SN-PDM for 20 min. Compared with unmodified SiNWAs, SN-PDM has little cytotoxicity and can improve cell attachment. All of these results demonstrated that SN-PDM could significantly enhance Ca(2+)-dependent transfection; this process depends on the amino groups' density of PDMAEMA on the surface, the Ca(2+) concentration, and the available Ca(2+)@DNA complex. Our study provides a potential novel and excellent means of gene delivery for therapeutic applications.