Honglian Dai

Different Inhibitory Effect and Mechanism of Hydroxyapatite Nanoparticles on Normal Cells and Cancer Cells In Vitro and In Vivo

Hydroxyapatite (HAP), similar to inorganic phase in bones, shows good biocompatibility and bioactivity as bone defect repairing material. Recently, nanoscaled HAP shows the special properties differing from bulk HAP in physics, chemistry and biology. This paper demonstrates that HAP nanoparticle (nHAP) possesses the ability for inhibiting cancer cell growth in vitro and in vivo. In vitro, after treatment with nHAP for 3 days, proliferation of human cancer cells are inhibited by more than 65% and by less than 30% for human normal cells. In vivo, injection of nHAP in transplanted tumor results in significant reduction (about 50%) of tumor size. The anticancer effect of nHAP is mainly attributed to high amount by endocytosis in cancer cells and inhibition on protein synthesis in cells. The abundant nHAP internalized in cancer cells around endoplasmic reticulum may inhibit the protein synthesis by decreasing the binding of mRNA to ribosome due to its high adsorption capacity for ribosome and arrest cell cycle in G0/G1 phase. nHAP shows no ROS-involved cytotoxicity and low cytotoxicity to normal cells. These results strongly suggest that nHAP can inhibit cancer cell proliferation and have a potential application in cancer treatment.

Luminescence Enhanced Eu3+/Gd3+ Co-Doped Hydroxyapatite Nanocrystals as Imaging Agents In Vitro and In Vivo

Biocompatible, biodegradable, and luminescent nano material can be used as an alternative bioimaging agent for early cancer diagnosis, which is crucial to achieve successful treatment. Hydroxyapatite (HAP) nanocyrstals have good biocompatibility and biodegradability, and can be used as an excellent host for luminescent rare earth elements. In this study, based on the energy transfer from Gd(3+) to Eu(3+), the luminescence enhanced imaging agent of Eu/Gd codoping HAP (HAP:Eu/Gd) nanocrystals are obtained via coprecipitation with plate-like shape and no change in crystal phase composition. The luminescence can be much elevated (up to about 120%) with a nonlinear increase versus Gd doping content, which is due to the energy transfer ((6)PJ of Gd(3+) → (5)HJ of Eu(3+)) under 273 nm and the possible combination effect of the cooperative upconversion and the successive energy transfer under 394 nm, respectively. Results demonstrate that the biocompatible HAP:Eu/Gd nanocrystals can successfully perform cell labeling and in vivo imaging. The intracellular HAP:Eu/Gd nanocrystals display good biodegradability with a cumulative degradation of about 65% after 72 h. This biocompatible, biodegradable, and luminescence enhanced HAP:Eu/Gd nanocrystal has the potential to act as a fluorescent imaging agent in vitro and in vivo.

Rare earth doped apatite nanomaterials for biological application

In most biological analyses, a sensitive detection technique is primarily dependent on the fluorescence labeling agent. New generation of fluorophores called rare earth doped apatite nanoparticle (REAnp) has the ability to emit near infrared radiations which are of low absorptivity by tissue chromophores and especially suitable for biological system imaging. Moreover, bioapatite is demonstrated to be an excellent candidate for biomedical applications because of its biocompatibility, biodegradability, and bioactivity. During recent years a lot of efforts have been made for achievement of REAnp for medical diagnostics and targeted therapeutics applications. In this review, we discuss the significance of REAnps in biological systems, different root of synthesis, and biological applications. Also we discuss the future studies for the effective biological applications of REAnps.

PDLLA/PRGD/β-TCP conduits build the neurotrophin-rich microenvironment suppressing the oxidative stress and promoting the sciatic nerve regeneration.

A novel nerve guidance conduit comprising poly{(lactic acid)-co-[(glycolic acid)-alt-(l-lysine)]} (PRGD), poly (d,l-lactic acid) (PDLLA) and β-tricalcium phosphate (β-TCP) was constructed to facilitate the peripheral nerve regeneration. From the comparative study, PDLLA/PRGD/β-TCP conduit achieved the best recovery in regard of the ultrastructure observation and the SFI evaluation. At the first stage of the injury (7 days), the maximum expression augments in ZnSOD (6.4 folds) and GPX4 (6.8 folds) were observed in PDLLA/PRGD/β-TCP group; while striking rise in actin (6.8 folds), tubulin (5.6 folds), and ERM components expressions were observed later (35 days). Meanwhile, compared with PDLLA and PDLLA/PRGD conduits, PDLLA/PRGD/β-TCP conduits achieved the highest local nerve growth factor (NGF) content and an accumulating BDNF content. We speculated that addition of RGD and β-TCP in the composites were the main positive factors to build the microenvironment rich in NGF and BDNF, which help to counteract with the oxidative stress and to boost the cytoskeletal protein expressions. Therefore, PDLLA/PRGD/β-TCP could be promising composites used in peripheral nerve regeneration.

Effects of Uptake of Hydroxyapatite Nanoparticles into Hepatoma Cells on Cell Adhesion and Proliferation

Hydroxyapatite nanoparticles (nano-HAPs) were prepared by homogeneous precipitation, and size distribution and morphology of these nanoparticles were determined by laser particle analysis and transmission electron microscopy, respectively. Nano-HAPs were uniformly distributed, with rod-like shapes sizes ranging from 44.6 to 86.8 nm. Attached overnight, suspended, and proliferating Bel-7402 cells were repeatedly incubated with nano-HAPs. Inverted microscopy, transmission electron microscopy, and fluorescence microscopy were used to observe the cell adhesion and growth, the culture medium containing nano-HAPs, the cell ultrastructure, and intracellular Ca2

Ultrasonically assisted preparation of poly(acrylic acid)/calcium phosphate hybrid nanogels as pH-responsive drug carriers

Biocompatible, biodegradable and stimuli-responsive nanomaterials can be used as drug carriers and to achieve controlled drug delivery, which is crucial for treating tumors and lowering drug side effects. Calcium phosphate (CaP) nanoparticles and poly(acrylic acid) (PAA) hydrogels can be used as biocompatible and pH-responsive drug carriers. In this study, based on the ultrasound effect, PAA/CaP hybrid nanogels (approximately 100nm, PDI<0.2) are obtained via the cross-linking of CaP nanoparticles and PAA molecules between the Ca2+ ions and -COOH groups. The PAA/CaP hybrid nanogels show good stability in biological media as well as no hemolysis and no cytotoxicity to L02 cells. Moreover, the PAA/CaP hybrid nanogels display an enhanced loading capacity (approximately 32%) for doxorubicin hydrochloride (DOX) compared to pure CaP nanoparticles (approximately 7.5%) and a pH-controlled drug release due to their dissolution in acidic environment. DOX can be delivered into cancer cells by the PAA/CaP hybrid nanogels, which show an inhibitory effect comparable to that of free DOX, although the inhibitory effect is delayed due to the slow release of DOX from the carriers. In vivo, the PAA/CaP hybrid nanogels cannot avoid the capture by the reticuloendothelial system; however, they show passive tumor targeting ability. In brief, the biocompatible, biodegradable and pH-responsive PAA/CaP hybrid nanogels have the potential to act as drug carriers for controlled drug release.

Promotion of peripheral nerve regeneration and prevention of neuroma formation by PRGD/PDLLA/β-TCP conduit: report of two cases

In the field of nerve repair, one major challenge is the formation of neuroma. However, reports on both the promotion of nerve regeneration and prevention of traumatic neuroma in the clinical settings are rare in the field of nerve repair. One of the reasons could be the insufficiency in the follow-up system. We have conducted 33 cases of nerve repair using PRGD/PDLLA/β-TCP conduit without any sign of adverse reaction, especially no neuroma formation. Among them, we have selected two cases as representatives to report in this article. The first case was a patient with an upper limb nerve wound was bridged by PRGD/PDLLA/β-TCP conduit and a plate fixation was given. After nearly 3-years’ follow-up, the examination results demonstrated that nerve regeneration effect was very good. When the reoperation was performed to remove the steel plate we observed a uniform structure of the regenerated nerve without the formation of neuroma, and to our delight, the implanted conduit was completely degraded 23 months after the implantation. The second case had an obsolete nerve injury with neuroma formation. After removal of the neuroma, the nerve was bridged by PRGD/PDLLA/β-TCP conduit. Follow-up examinations showed that the structure and functional recovery were improved gradually in the 10-month follow-up; no end-enlargement and any other abnormal reaction associated with the characteristic of neuroma were found. Based on our 33-case studies, we have concluded that PRGD/PDLLA/β-TCP nerve conduit could both promote nerve regeneration and prevent neuroma formation; therefore, it is a good alternative for peripheral nerve repair.

Synthesis, characterization and biological evaluation of poly [LA-co-(Glc-alt-Lys)] for nerve regeneration scaffold

A novel nerve repairing material poly [LA-co-(Glc-alt-Lys)] (PLGL) was synthesized. The viability and growth of Schwann cells (SCs) co-cultured with poly (D, Llactic acid) (PDLLA) films (control group) and PLGL films were evaluated by MTTassay and SEM observation. Then, contact angle measurement, histological assessment and enzyme-linked immunosorbent assay (ELISA) testing on inflammatory-related cytokines such as IL-10 and TGF-β1 were performed. The results showed that, compared with PDLLA, PLGL films possesses better hydrophilicity, biocompatibility, degradation property and less inflammatory reaction. The present study indicated that PLGL scaffolds would meet the requirements of artificial nerve scaffold and have a potential application in the fields of nerve regeneration.

Effects of crystallinity and surface modification of calcium phosphate nanoparticles on the loading and release of tetracycline hydro-chloride

The influences of crystallinity and surface modification of calcium phosphate nanoparticles (nCaP) on their drug loading capacity and drug release profile were studied in the present investigation. The CaP nanoparticles with different crystallinity were prepared by precipitation method under different temperatures. CaP nanoparticles with lower crystallinity exhibited higher drug loading capacity. The samples were characterized by XRD, FT-IR, SEM, TEM and BET surface area analyzer respectively. The drug loading capacity of nCaP was evaluated to tetracycline hydro-chloride (TCH). The internalization of TCH loaded nCaP in cancer cell was observed by florescence microscope. nCaP could be stabilized and dispersed in aqueous solution by poly(acrylic acid) surface modification agent, leading to enhanced drug loading capacity. The drug release was conducted in different pH environment and the experimental data proved that nCaP were pH sensitive drug carrier, suggesting that nCaP could achieve the controlled drug release in intracellular acidic environment. Furthermore, nCaP with higher crystallinity showed lower drug release rate than that of lower crystallinity, indicating that the drug release profile could be adjusted by crystallinity of nCaP. nCaP with adjustable drug loading and release properties are promising candidate as drug carrier for disease treatment.

Degradation characteristics, cell viability and host tissue responses of PDLLA-based scaffold with PRGD and β-TCP nanoparticles incorporation.

This study is aimed to evaluate the degradation characteristics, cell viability and host tissue responses of PDLLA/PRGD/β-TCP (PRT) composite nerve scaffold, which was fabricated by poly(d, l-lactic acid) (PDLLA), RGD peptide(Gly-Arg-Gly-Asp-Tyr, GRGDY, abbreviated as RGD) modified poly-{(lactic acid)-co-[(glycolic acid)-alt-(l-lysine)]}(PRGD) and β-tricalcium phosphate (β-TCP). The scaffolds’ in vitro degradation behaviors were investigated in detail by analysing changes in weight loss, pH and morphology. Then, the 3-(4,5-dimethyl-2-thiazolyl) -2,5-diphenyl-2 -H-tetrazolium bromide (MTT) assay and cell live/dead assay were carried out to assess their cell viability. Moreover, in vivo degradation patterns and host inflammation responses were monitored by subcutaneous implantation of PRT scaffold in rats. Our data showed that, among the tested scaffolds, the PRT scaffold had the best buffering capacity (pH = 6.1–6.3) and fastest degradation rate (12.4%, 8 weeks) during in vitro study, which was contributed by the incorporation of β-TCP nanoparticles. After in vitro and in vivo degradation, the high porosity structure of PRT could be observed using scanning electron microscopy. Meanwhile, the PRT scaffold could significantly promote cell survival. In the PRT scaffold implantation region, less inflammatory cells (especially for neutrophil and lymphocyte) could be detected. These results indicated that the PRT composite scaffold had a good biodegradable property; it could improve cells survival and reduced the adverse host tissue inflammation responses.