Hydroxyapatite nanoparticles modified by branched polyethylenimine are effective non-viral vectors for siRNA transfection of hepatoma cells in vitro

Biomaterial-assisted tumor therapy: A brief review of hydroxyapatite nanoparticles and its composites used in bone tumors therapy

Malignant bone tumors can inflict significant damage to affected bones, leaving patients to contend with issues like residual tumor cells, bone defects, and bacterial infections post-surgery. However, hydroxyapatite nanoparticles (nHAp), the principal inorganic constituent of natural bone, possess numerous advantages such as high biocompatibility, bone conduction ability, and a large surface area. Moreover, nHAp's nanoscale particle size enables it to impede the growth of various tumor cells via diverse pathways. This article presents a comprehensive review of relevant literature spanning the past 2 decades concerning nHAp and bone tumors. The primary goal is to explore the mechanisms responsible for nHAp's ability to hinder tumor initiation and progression, as well as to investigate the potential of integrating other drugs and components for bone tumor diagnosis and treatment. Lastly, the article discusses future prospects for the development of hydroxyapatite materials as a promising modality for tumor therapy.

Amphiphilic Anionic Oligomer-Stabilized Calcium Phosphate Nanoparticles with Prospects in siRNA Delivery via Convection-Enhanced Delivery

Convection-enhanced delivery (CED) has been introduced as a concept in cancer treatment to generate high local concentrations of anticancer therapeutics and overcome the limited diffusional distribution, e.g., in the brain. RNA interference provides interesting therapeutic options to fight cancer cells but requires nanoparticulate (NP) carriers with a size below 100 nm as well as a low zeta potential for CED application. In this study, we investigated calcium phosphate NPs (CaP-NPs) as siRNA carriers for CED application. Since CaP-NPs tend to aggregate, we introduced a new terpolymer (o14PEGMA(1:1:2.5) NH₃) for stabilization of CaP-NPs intended for delivery of siRNA to brain cancer cells. This small terpolymer provides PEG chains for steric stabilization, and a fat alcohol to improve interfacial activity, as well as maleic anhydrides that allow for both labeling and high affinity to Ca(II) in the hydrolyzed state. In a systematic approach, we varied the Ca/P ratio as well as the terpolymer concentration and successfully stabilized NPs with the desired properties. Labeling of the terpolymer with the fluorescent dye Cy5 revealed the terpolymer’s high affinity to CaP. Importantly, we also determined a high efficiency of siRNA binding to the NPs that caused very effective survivin siRNA silencing in F98 rat brain cancer cells. Cytotoxicity investigations with a standard cell line resulted in minor and transient effects; no adverse effects were observed in organotypic brain slice cultures. However, more specific cytotoxicity investigations are required. This study provides a systematic and mechanistic analysis characterizing the effects of the first oligomer of a new class of stabilizers for siRNA-loaded CaP-NPs.

In situ functionalizing calcium phosphate biomaterials with curcumin for the prevention of bacterial biofilm infections

This study developed a novel bioactive bone substitute (hydroxyapatite, HA) with improved anti-biofilm activity by functionalizing with curcumin (anti-biofilm compound) which provide sufficient flux of curcumin concentration for 14 days. The released curcumin acts to inhibit biofilm formation and control the number of viable planktonic cells simultaneously. To prepare curcumin-functionalized HA, different concentrations of curcumin (up to 3% w/v) were added simultaneously during the precipitation process of HA. The highest loading (50 mg/g HA) of curcumin onto HA was achieved with 2% w/v of curcumin. Physicochemical characterizations of curcumin-functionalized HA composites revealed that curcumin was successfully incorporated onto HA. Curcumin was sustainably released over 14 days, while higher curcumin release was observed in acidic condition (pH 4.4) compared to physiological (pH 7.4). The cytotoxicity assays revealed that no significant difference on bone cells growth on curcumin-functionalized HA and non-functionalized HA. Curcumin-functionalized HA was effective to inhibit bacterial cell attachment and subsequent biofilm maturation stages. The anti-biofilm effect was stronger against Staphylococcus aureus compared to Pseudomonas aeruginosa. The curcumin-functionalized HA composite significantly delayed the maturation of S. aureus compared to non-functionalized HA in which microcolonies of cells only begin to appear at 96 h. Up to 3.0 log reduction in colony forming unit (CFU)/mL of planktonic cells was noted at 24 h of incubation for both microorganisms. Thus, in this study we have suggested that curcumin loaded HA could be an alternative antimicrobial agent to control the risk of infections in post-surgical implants.

Facile synthesis of biodegradable flower-like hydroxyapatite for drug and gene delivery

Controlled synthesis of hierarchical hydroxyapatite materials is a hot research topic because of the excellent biocompatibility and bioactivity of the materials. In this study, flower-like hydroxyapatite spheres (FHAPS) were facile synthesized in one pot using Al(OH)₃ as a structure-directing agent. The prepared FHAPS comprised nanosheets possessing a uniform diameter of approximately 4 µm. Notably, the FHAPS can be degraded in solutions with a pH of 5.5 for 144 h or incubated with cells for 48 h. In addition, the FHAPS have rough surfaces, which exhibit high loading contents for the anticancer drug doxorubicin (DOX, 9.1%) and siRNA (2.0%). Thus, the FHAPS can effectively deliver DOX into drug-resistant breast cancer cells to exert an excellent killing effect compared with free DOX and transfect siRNA into tumor cells to interfere with the expression of the target protein. Taken together, this work successfully prepared FHAPS via a convenient synthesis route that shows high delivery efficiency for anticancer drugs and siRNA.

Synergism of wt-p53 and synthetic material in local nano-TAE gene therapy of hepatoma: comparison of four systems and the possible mechanism

Background

TAE-gene therapy for hepatoma, incorporating the tumor-targeted therapeutic efficacy of trans-arterial embolization, hydroxyapatite nanoparticles (nHAP) and anti-cancer wild-type p53 gene (wt-p53), was presented in our former studies (Int J Nanomedicine 8:3757-68, 2013, Liver Int 32:998-1007, 2012). However, the incompletely antitumoral effect entails defined guidelines on searching properer materials for this novel therapy.

Methods

Unmodified nHAP, Ca⁽²⁺⁾ modified nHAP, poly-lysine modified nHAP and liposome were separately used to form U-nanoplex, Ca-nanoplex, Pll-nanoplex, L-nanoplex respectively with wt-p53 expressing plasmid. The four nanoplexs were then applied in vitro for human normal hepacyte L02 and hepatoma HePG2 cell line, and in vivo for rabbits with hepatic VX2 tumor by injection of nanoplexs/lipiodol emulsion into the hepatic artery in a tumor target manner. The distribution, superficial potential, physical structure, morphology and chemical compositions of nanoplexs were evaluated by TEM, SEM, EDS etc., with the objective of understanding their roles in hepatoma TAE-gene therapy.

Results

In vitro, L-nanoplex managed the highest gene transferring efficiency. Though with the second highest transfection activity, Pll-nanoplex showed the strongest tumor inhibition activity while maintaining safe to the normal hepacyte L02. In fact, only Pll-nanoplex can combine both the antitumoral effect to HePG2 and safe procedure to L02 among the four systems above. In vivo, being the only one with successful gene transference to hepatic VX2 tumor, Pll-nanoplex/lipiodol emulsion can target the tumor more specifically, which may explain its best therapeutic effect and hepatic biologic response. Further physical characterizations of the four nanoplexs suggested particle size and proper electronic organic surface may be crucial for nano-TAE gene therapy.

Conclusion

Pll-nanoplex is the most proper system for the combined therapy due to its selectively retention in liver cancer cells, secondary to its morphological and physico-chemical properties of nanometric particle size, steady emulsion, proper organic and electronic surface.

Anisamido-Polyethylenimines as Efficient Nonviral Vectors for the Transport of Plasmid DNA to Sigma Receptor-Bearing Cells In Vitro

Site-specific delivery of therapeutics promises better outcomes in the treatment of diseases. A small ligand, anisamide, has been shown to specifically bind sigma receptors highly overexpressed on prostate cancer cells, one of the leading cancers causing deaths worldwide. Here, anisamide-tethered polyethylenimine polymers (AP) have been synthesized and evaluated for their capability to transport nucleic acid across the cell membrane. A series of modified polymers (AP-1 to AP-4) was synthesized, physicochemically characterized, and evaluated for their transfection efficiency and cytotoxicity. Postconjugation, there was a marginal decrease in the buffering capacity; however, it did not diminish the ultimate objective of the study rather improved the transfection efficiency and decreased the cytotoxicity making these polymers as efficient and safe vectors for nucleic acid delivery. All the modified polymers displayed enhanced capability to deliver DNA inside the cells. Among the series, the modified polymer, AP-4 (10% attempted substitution), exhibited the highest transfection in HEK293 cells having abundant sigma receptors with minimal cytotoxicity. The projected polymer also showed complete protection of bound DNA against enzymatic degradation. Altogether, the results demonstrated targeting ability of the proposed polymers to deliver nucleic acid to sigma receptor-bearing cells in vitro.