Publications in March and April 2013

In March and April 262 publications were released about Chitosan, which mainly focused on animal and human studies, nanoparticles and pharmaceutical preparations. The most successful nations in the field of chitosan research have been: China (83 articles), India (31) and USA (22).

Table: List of scientific journals publishing most chitosan-related articles in March and April 2013.
Source: GoPubMed

Several reports examined the usability of chitosan and its derivatives for vaccine production. Here we present two publications, which offer new and innovative application options for chitosan that might provide novel impetus for vaccine research.

Fully embeddable chitosan microneedles as a sustained release depot for intradermal vaccination.

Chen M.C., Huang S.F., Lai K.Y. and Ling M.H.; Biomaterials. Vol. 34(12):3077-86. April 2013.

In the present study a transdermal delivery system for vaccinations was invented. It was designed from biodegradable chitosan microneedles, which were mounted to a stable poly(L-lactide-co-D,L-lactide) (PLA) array. Chitosan microneedles served as a carrier for antigens like ovalbumin (OVA) and were fully embeddable in the skin. The efficiency of drug delivery was tested in vivo by injecting microneedles into rat skin.

Results:

Chitosan microneedles remained in the skin after injection No transdermal patch required Penetration depth: 600 µm Microneedles gradually degraded Prolonged OVA exposure for up to 14 days Sustained antibody response for at least 6 weeks

Conclusion: Embeddable and biodegradable chitosan microneedles proved to be suitable for the administration of vaccines. Since these needle remained within the skin the OVA exposure was prolonged, which in turn extended the specific antibody response to OVA antigen. In comparison to traditional intramuscular immunization the immune response was clearly prolonged by the novel injection method.

Source: http://www.ncbi.nlm.nih.gov/pubmed/23369214

Evaluation of the effectiveness and safety of chitosan derivatives as adjuvants for intranasal vaccines.

Kobayashi T., Fukushima K., Sannan T. et al.; Viral Immunology. Vol. 26(2):133-42. April 2013.

The aim of this study was to examine the adjuvant activity of chitosan, when added to intranasal (i.n.) vaccines. Adjuvants are added to i.n. vaccines to increase the mucosal immune response. Such adjuvants can be derived from bacterial toxins like cholera toxin or E.coli heat-labile toxin. However, these adjuvants cause some side effects. Therefore, novel adjuvants are required, which are safer than existing immune stimulants.

Chitosan is a strong activator of macrophages and NK cells. The author of the study examined chitosan microparticles or cationized chitosan, which were i.n. co-administered with ovalbumin (OVA). OVA served as antigen model. In vivo experiments were performed on BALB/c mice, polymeric Ig receptor knockout (pIgR-KO) mice and cynomolgus monkeys.

Results:

• Chitosan microparticles: 1-20 µm, 50 kDa, 85% degree of deacetylation
• Cationized chitosan: 1000 kDa, 85% degree of deacetylation
• Immune response to OVA antigen was enhanced by both chitosan adjuvants
  • pIgR-KO mice: high IgA response in serum
  • BALB/c mice and cynomolgus monkeys: high IgG response in serum
• No detrimental effects on the blood count of cynomolgus monkeys

Conclusion: Chitosan adjuvants improve the mucosal immune response when administered intranasally with the antigen OVA. The i.n. vaccination enhanced the humoral immunity by increasing mucosal S-IgA and anti-OVA IgG in the serum. Since no side effects were detected upon immunization, chitosan could be an effective and safe mucosal adjuvant for vaccines.

Source: http://www.ncbi.nlm.nih.gov/pubmed/23509985