This study deals with the process of optimization and synthesis of
Poly(3-hydroxybutyrate) microspheres with encapsulated
Cl-amidine.
Cl-amidine is an inhibitor of
peptidylarginine deiminases (PADs), a group of
calcium-dependent
enzymes, which play critical roles in a number of pathologies, including autoimmune and
neurodegenerative diseases, as well as
cancer. While
Cl-amidine application has been assessed in a number of in vitro and in vivo models; methods of controlled release delivery remain to be investigated. P(3HB)
microspheres have proven to be an effective delivery system for several compounds applied in antimicrobial, wound healing,
cancer, and cardiovascular and regenerative disease models. In the current study, P(3HB)
microspheres with encapsulated
Cl-amidine were produced in a size ranging from ~4-5 µm and characterized for surface morphology, porosity, hydrophobicity and
protein adsorption, in comparison with empty P(3HB)
microspheres.
Cl-amidine encapsulation in P(3HB)
microspheres was optimized, and these were found to be less hydrophobic, compared with the empty
microspheres, and subsequently adsorbed a lower amount of
protein on their surface. The release kinetics of
Cl-amidine from the
microspheres were assessed in vitro and expressed as a function of encapsulation efficiency. There was a burst release of ~50%
Cl-amidine in the first 24 h and a zero order release from that point up to 16 days, at which time point ~93% of the drug had been released. As
Cl-amidine has been associated with anti-
cancer effects, the
Cl-amidine encapsulated
microspheres were assessed for the inhibition of
vascular endothelial growth factor (
VEGF) expression in the mammalian
breast cancer cell line SK-BR-3, including in the presence of the anti-proliferative drug
rapamycin. The cytotoxicity of the combinatorial effect of
rapamycin with
Cl-amidine encapsulated P(3HB)
microspheres was found to be 3.5% more effective within a 24 h period. The cells treated with
Cl-amidine encapsulated
microspheres alone, were found to have 36.5% reduction in
VEGF expression when compared with untreated SK-BR-3 cells. This indicates that controlled release of
Cl-amidine from P(3HB)
microspheres may be effective in anti-
cancer treatment, including in synergy with chemotherapeutic agents. Using controlled drug-delivery of
Cl-amidine encapsulated in
Poly(3-hydroxybutyrate) microspheres may be a promising novel strategy for application in PAD-associated pathologies.