Publication May and June 2013

231 articles about chitosan and chitosan derivatives have been published in May and June 2013. The main topics focused on animal and human studies and on chitosan-based nanoparticles and pharmaceutical preparations. Moreover, the physico-chemical properties and pH sensitivity of various chitosan derivatives were intensively studied. Among the top nations of chitosan research are again: China (76 articles), USA (30) and India (14).

Table: Leading journals, publishing the highest number of chitosan-related articles in May and June 2013.
Source: GoPubMed

Chitosan-based nanoparticles can serve as drug delivery systems and possess great potential in the treatment of tumours. Conventional chemotherapies are often associated with adverse side effects and many tumour cells display drug resistance. Therefore, novel and gentler therapies are constantly tested, which might also facilitate multidrug delivery to tumorous cells. Below, we present two interesting reports about chitosan-based nanoparticles, which might be beneficial for early cancer diagnosis and therapy. 

Gadolinium-loaded chitosan nanoparticles as magnetic resonance imaging contrast agents for the diagnosis of tumour.

Zhang L., Liu Y., Yu D. and Zhangl N.; Journal of Biomedical Nanotechnology. Vol. 9(5):863-9. Mai 2013

In the present study chitosan-based nanoparticles (CSNPs) were modified with gadolinium (Gd) to improve the early diagnosis of tumours by magnetic resonance imaging (MRI). Gd ions are paramagnetic and display a characteristic movement in magnetic fields. Therefore they can enhance the contrast of MRI scans, which visualise internal body structures by using a strong magnetic field.

Gd ions were conjugated to the surface of chitosan nanoparticles (Gd-CSNPs). The physico-chemical properties, toxicity and contrast agent efficiency of Gd-CSNPs were studied.

Results:

• Spherical or ellipsoid particle shape
• Mean particle size: 111 nm (CSNPs) and 153 nm (Gd-CSNPs)
• Zeta potential: 22.3 mV (CSNPs) and 13.9 mV (Gd-CSNPs)
• Relaxation rate: 7.509 mM-1s-1
• High T1 relaxivity
• No cytotoxicity in mouse B16 melanoma cells

Conclusions: The contrast of MRI scans was enhanced by Gd-modified chitosan nanoparticles, as they improved the T1 relaxivity. T1 signals represent the longitudinal relaxation time of MR contrast agents and determine brightness and contrast of MRI images. Gd-CSNPs displayed no obvious cytotoxicity to the tested tumour cells, while Gd is toxic by itself. Thus, Gd-CSNPs possess great potential as MRI contrast agent and might improve the early detection and delineation of tumorous from normal tissue.

Source: http://www.ncbi.nlm.nih.gov/pubmed/23802417

Codelivery of mTERT siRNA and paclitaxel by chitosan-based nanoparticles promoted synergistic tumor suppression.

Wei W., Lv P.P., Chen X.M. et al.; Biomaterials. Vol. 34(15):3912-23. Mai 2013

Small interfering RNAs (siRNAs) are promising tools of anticancer therapy. They can suppress the expression of tumour-associated proteins and promote apoptosis of cancer cells. The aim of this study was to overcome the obstacles of siRNA delivery, since clinical use of siRNA therapy is restricted by poor cellular uptake and strong enzymatic degradation.

To improve siRNA delivery and to allow oral administration, siRNA was encapsulated into nanoparticles composed of N-((2-hydroxy-3-trimethylammonium) propyl) chitosan chloride (HNP). The target protein for siRNA-mediated knockdown was the telomerase reverse transcriptase (TERT), an enzyme, which is linked to unregulated division of tumour cells.

Results:

HNPs protect siRNA from enzymatic degradation Improved siRNA permeability in the intestinal tract Enhanced intracellular uptake of siRNA into tumour cells HNPs ferry hydrophobic chemotherapeutic drugs like paclitaxel (PTX) Simultaneous delivery of siRNA and PTX

Conclusions: The chitosan-based nanocarriers could carry TERT siRNA and PTX simultaneously. HNPs enhance intestinal adsorption and cellular uptake and thereby increase the intratumoral drug concentration. The codelivery of siRNA and PTX had a synergistic effect in the tumour and inhibited its growth significantly.

Source: http://www.ncbi.nlm.nih.gov/pubmed/23453062