Engineering and characterisation of BCG-loaded polymeric microneedles

Area of Science:

• Biomaterials Science
• Immunology
• Pharmaceutical Technology

Background:

• Traditional Bacillus Calmette-Guérin (BCG) vaccination involves intradermal injections, which can cause discomfort and require trained personnel.
• Microneedle technology offers a potential alternative for painless and efficient transdermal drug and vaccine delivery.

Purpose of the Study:

• To fabricate and characterize BCG-loaded sodium alginate-trehalose microneedle patches using micromould casting.
• To compare the immunogenicity and efficacy of these microneedle patches with conventional injectable BCG vaccines.

Main Methods:

• Microneedle patches were formulated with 10% sodium alginate and 20% trehalose.
• Characterization included optical microscopy, scanning electron microscopy, and folding endurance tests.
• Immunogenicity was assessed by measuring serum IgG, total leucocyte count (TLC), granulocyte count, lymphocyte count, and C-reactive protein (CRP) in rats.

Main Results:

• The fabricated microneedle patches exhibited a thickness of 0.8 mm and microneedle projections of 272 ± 12 µm, with excellent folding endurance (>300).
• BCG-loaded microneedle patches induced immune responses comparable to injectable BCG, evidenced by significant increases in lymphocytes, granulocytes, and peptide-specific IgG.
• Specific increases observed: IgG from 3 g/L to 5.98 g/L, leucocytes from 2.6 × 10^9/L to 18.45 × 10^9/L, granulocytes from 14.4% to 29.15%, and lymphocytes from 58.75% to 85.3%.

Conclusions:

• Polymeric microneedle patches loaded with BCG are suitable for transdermal vaccine delivery.
• This microneedle patch system provides an effective and potentially less uncomfortable alternative to traditional BCG injections.