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Tissue distribution of DNA-Hsp65/TDM-loaded PLGA microspheres and uptake by phagocytic cells

Ana Paula F Trombone1, Celio L Silva, Luciana P Almeida

  • 1Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av, Bandeirantes, 3900, 14049-900, Ribeirão Preto, SP, Brasil. tromboneapf@usp.br

Genetic Vaccines and Therapy
|September 21, 2007
PubMed

Insights

Poly (lactic-co-glycolic acid) microspheres effectively deliver DNA-Hsp65/TDM vaccines, widely distributing to organs and activating immune cells. These gene carriers show promise for future vaccination strategies.

Area of Science:

  • Biomedical Engineering
  • Immunology
  • Vaccine Development

Background:

  • Poly (lactic-co-glycolic acid) (PLGA) microspheres are utilized as delivery vehicles for DNA vaccines.
  • Understanding the biodistribution and immune cell interaction of these microspheres is crucial for optimizing vaccine efficacy.

Purpose of the Study:

  • To investigate the organ distribution of PLGA microspheres containing DNA-Hsp65/TDM after intramuscular administration in mice.
  • To assess the immune response, including antigen-presenting cell uptake and lymph node cell activation, induced by these microspheres.
  • To elucidate the intracellular trafficking and degradation pathways of the microspheres.

Main Methods:

  • Intramuscular administration of PLGA microspheres loaded with DNA-Hsp65/TDM in BALB/c mice.
  • Analysis of microsphere distribution in various organs.
  • Flow cytometry to evaluate antigen-presenting cell (APC) phagocytosis and expression of costimulatory molecules (CD80, CD86) and MHC class II on draining lymph node cells.
  • Intracellular trafficking studies to determine microsphere location within APCs over time.

Main Results:

  • PLGA microspheres were widely distributed across multiple organs following intramuscular injection.
  • Microspheres were efficiently phagocytosed by antigen-presenting cells, including macrophages and dendritic cells.
  • Significant upregulation of CD80, CD86, and MHC class II was observed on draining lymph node cells, indicating immune activation.
  • Microspheres were retained in early endosomal compartments and not detected in late endosomes/lysosomes up to 15 days post-administration, suggesting early hydrolysis.

Conclusions:

  • PLGA microspheres serve as effective gene carriers for DNA-Hsp65/TDM vaccination, demonstrating broad organ distribution and potent immune cell activation.
  • The observed immune cell activation and early hydrolysis within APCs provide valuable insights into the mechanism of action for PLGA microsphere-based vaccines.
  • These findings support the potential clinical application of PLGA microspheres in advanced vaccination strategies.

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