A combination of cisplatin-eluting gelatin microspheres and flavopiridol enhances anti-tumour effects in a rabbit VX2 liver tumour model

Current Trends in Gelatin-Based Drug Delivery Systems

Gelatin is a highly versatile natural polymer, which is widely used in healthcare-related sectors due to its advantageous properties, such as biocompatibility, biodegradability, low-cost, and the availability of exposed chemical groups. In the biomedical field, gelatin is used also as a biomaterial for the development of drug delivery systems (DDSs) due to its applicability to several synthesis techniques. In this review, after a brief overview of its chemical and physical properties, the focus is placed on the commonly used techniques for the development of gelatin-based micro- or nano-sized DDSs. We highlight the potential of gelatin as a carrier of many types of bioactive compounds and its ability to tune and control select drugs' release kinetics. The desolvation, nanoprecipitation, coacervation, emulsion, electrospray, and spray drying techniques are described from a methodological and mechanistic point of view, with a careful analysis of the effects of the main variable parameters on the DDSs' properties. Lastly, the outcomes of preclinical and clinical studies involving gelatin-based DDSs are thoroughly discussed.

Progress of gelatin-based microspheres (GMSs) as delivery vehicles of drug and cell

Gelatin has various attractive features as biomedical materials, for instance, biocompatibility, low immunogenicity, biodegradability, and ease of manipulation. In recent years, various gelatin-based microspheres (GMSs) have been fabricated with innovative technologies to serve as sustained delivery vehicles of drugs and genetic materials as well as beneficial bacteria. Moreover, GMSs have exhibited promising potentials to act as both cell carriers and 3D scaffold components in tissue engineering and regenerative medicine, which not only exhibit excellent injectability but also could be integrated into a macroscale construct with the laden cells. Herein, we aim to thoroughly summarize the recent progress in the preparations and biomedical applications of GMSs and then to point out the research direction in future. First, various methods for the fabrication of GMSs will be described. Second, the recent use of GMSs in tumor embolization and in the delivery of cells, drugs, and genetic material as well as bacteria will be presented. Finally, several key factors that may enhance the improvement of GMSs were suggested as delivery vehicles.

Prospects of multitarget drug designing strategies by linking molecular docking and molecular dynamics to explore the protein-ligand recognition process

The designing of drugs that can simultaneously affect different protein targets is one novel and promising way to treat complex diseases. Multitarget drugs act on multiple protein receptors each implicated in the same disease state, and may be considered to be more beneficial than conventional drug therapies. For example, these drugs can have improved therapeutic potency due to synergistic effects on multiple targets, as well as improved safety and resistance profiles due to the combined regulation of potential primary therapeutic targets and compensatory elements and lower dosage typically required. This review analyzes in-silico methods that facilitate multitarget drug design that facilitate the discovery and development of novel therapeutic agents. Here presented is a summary of the progress in structure-based drug discovery techniques that study the process of molecular recognition of targets and ligands, moving from static molecular docking to improved molecular dynamics approaches in multitarget drug design, and the advantages and limitations of each.

Automated Quantification of Tumor Viability in a Rabbit Liver Tumor Model after Chemoembolization Using Infrared Imaging

The rabbit VX2 tumor is a fast-growing carcinoma model commonly used to study new therapeutic devices, such as catheter-based therapies for patients with inoperable hepatocellular carcinoma. The evaluation of tumor viability after such locoregional therapies is essential to directing hepatocellular carcinoma management. We used infrared microspectroscopy for the automatic characterization and quantification of the VX2 liver tumor viability after drug-eluting beads transarterial chemoembolization (DEB-TACE). The protocol consisted of K-means clustering followed by principal component analysis (PCA) and linear discriminant analysis (LDA). The K-means clustering was used to classify the spectra from the infrared images of control or treated tumors and to build a database of many tissue spectra. On the basis of this reference library, the PCA-LDA analysis was used to build a predictive model to identify and quantify automatically tumor viability on unknown tissue sections. For the DEB group, the LDA model determined that the surface of tumor necrosis represented 91.6% ± 8.9% (control group: 33.1% ± 19.6%; Mann-Whitney P = 0.0004) and the viable tumor 2.6% ± 4% (control group: 62.2% ± 15.2%; Mann-Whitney P = 0.0004). Tissue quantification measurements correlated well with tumor necrosis (r = 0.827, P < 0.0001) and viable tumor (r = 0.840, P < 0.0001). Infrared imaging and PCA-LDA analysis could be helpful for easily assessing tumor viability.

Comparison of two different laparotomy methods for modeling rabbit VX2 hepatocarcinoma

AIM: To compare two different laparotomy methods for modeling rabbit VX2 hepatocarcinoma.

METHODS: Thirty New Zealand rabbits were randomly divided into two groups: A and B. Group A was assigned a traditional laparotomy method (embedding tumor fragments directly into the liver with tweezers). Group B was subjected to an improved laparotomy method (injection of tumor fragments into the liver through a 15 G syringe needle). The operation time, incision length, incision infection rate, and mortality rate were compared between the two groups after laparotomy. Magnetic resonance imaging (MRI) was performed to evaluate tumor formation rates and the characteristics of the tumors 2 wk after laparotomy.

RESULTS: The mean operation times for the two groups (Group A vs Group B) were 23.2 ± 3.4 min vs 17.5 ± 2.9 min (P < 0.05); the incision length was 3.3 ± 0.5 cm vs 2.4 ± 0.6 cm (P < 0.05); and the mortality rate after 2 wk was 26.7% vs 0% (P < 0.05); all of these outcomes were significantly different between the two groups. The incision infection rates in the two groups were 6.7% vs 0% (P > 0.05), which were not significantly different. MRI performed after 2 weeks showed that the tumor formation rates in the two groups were 90.9% vs 93.3% (P > 0.05). These rates were not significantly different between the two groups. The celiac implantation rate and abdominal wall metastasis rate in the two groups were 36.4% vs 13.3% (P < 0.05) and 27.2% vs 6.7% (P < 0.05), respectively, which were significantly different between the two groups.

CONCLUSION: The tumor formation rates were not significantly different between the two methods for modeling rabbit VX2 hepatocarcinoma. However, the improved method is recommended because it has certain advantages.

Enhanced antitumor effect of tirapazamine delivered intraperitoneally to VX2 liver tumor-bearing rabbits subjected to transarterial hepatic embolization

PURPOSE

We evaluated the effects of the combination of Tirapazamine (TPZ), activated preferentially under hypoxic conditions, and gelatin microspheres (GMS) on the tumor growth ratio in rabbits.

METHODS

We assigned 20 liver tumor-bearing Japanese white rabbits to 4 equal groups. Group 1 received 1 ml of saline intra-arterially (i.a.) and 20 ml of saline intraperitoneally (i.p.; saline group). Group 2 was injected with GMS i.a. and 20 ml saline i.p. (GMS group). Group 3 received 1 ml of saline i.a. and 300 mg/m(2) of TPZ i.p. (TPZ group), and group 4 was treated with GMS i.a. and 300 mg/m(2) of TPZ i.p. (GMS + TPZ group). The infusion of GMS was stopped when the blood flow stagnated. Before and 7 days after treatment, the liver tumor volumes were measured as the total number of pixels on 0.3Tesla (T) magnetic resonance imaging (MRI) scans.

RESULTS

The tumor growth ratio (mean ± standard deviation) of the saline, GMS, TPZ, and GMS + TPZ groups was 519.15 ± 93.78, 279.24 ± 91.83, 369.78 ± 95.73, and 119.87 ± 17.62, respectively. The difference between the GMS + TPZ group and the other groups was statistically significant (P < 0.05).

CONCLUSIONS

Our results show that the combination of TPZ i.p. and GMS i.a. enhanced the antitumor effect of TPZ. This procedure may represent a new alternative treatment for patients with hepatic cell carcinoma.

Anti-tumour effects of transcatheter arterial embolisation administered in combination with thalidomide in a rabbit VX2 liver tumour model

OBJECTIVE

Using a liver tumour model we investigated whether thalidomide enhances the anti-tumour effect of transcatheter arterial embolisation (TAE).

METHOD

First, the viability of VX2 tumour cells co-cultured with thalidomide in a 21% and 1% O(2) atmosphere was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Second, we randomly assigned 20 rabbits bearing VX2 liver tumours to 4 groups: Group 1 (thalidomide plus TAE), Group 2 (TAE only), Group 3 (thalidomide only) and Group 4 (control). Thalidomide was orally administered for 5 days. The anti-tumour effects were assessed by the tumour proliferation rate using MRI and by immunohistochemical analysis of the area of intratumoural vessels. Analysis of variance and Tukey's honestly significant difference test were used for statistical analysis.

RESULTS

The viability of cells grown under hypoxic and normal conditions was not significantly different, nor was there a difference among the four groups. The tumour size increased by 55.9±29.3% in Group 1, 250.6±73.3% in Group 2, 355.2±51.7% in Group 3 and 424.7±110.7% in Group 4; the difference between Group 1 and the other three groups was significant. The area of intratumour vessels in specimens was 0.22±0.28% in Group 1, 0.42±0.29% in Group 2, 1.44±1.00% in Group 3 and 6.00±2.17% in Group 4; the difference between Group 1 and the other groups was statistically significant, as was the difference between Groups 3 and 4.

CONCLUSION

Thalidomide used in combination with TAE enhanced anti-tumour effects in rabbits bearing VX2 liver tumours.

In-silico approaches to multi-target drug discovery : computer aided multi-target drug design, multi-target virtual screening

Multi-target drugs against selective multiple targets improve therapeutic efficacy, safety and resistance profiles by collective regulations of a primary therapeutic target together with compensatory elements and resistance activities. Efforts have been made to employ in-silico methods for facilitating the search and design of selective multi-target agents. These methods have shown promising potential in facilitating drug discovery directed at selective multiple targets.