The PLGA nanoparticles for sustainable release of CGRP to ameliorate the inflammatory and vascular disorders in the lung of CGRP-deficient rats

Abstract

The calcitonin gene-related peptide (CGRP) has been demonstrated relating to vascular and inflammatory regulations not only the nerve systems. As the anti-inflammation factor and the most potent vasodilator, the CGRP holds therapeutic potentials for the treatment of cardiovascular diseases which was, however, limited by its peptide nature and short half-life. With advantages in improving the stability, circulation time and protection from degradation, the nanoparticles were promising as delivery carriers for the peptide. Nevertheless, few nanoparticulate systems were developed to deliver the CGRP peptide for the modulation of vascular or inflammatory functions instead of neural regulation. In this study, the CGRP was encapsulated into the poly (lactic-co-glycolic acid) (PLGA) nanoparticle for sustained release of CGRP in vivo. The nanoparticles recovered the systemic level of CGRP and the vascular inflammatory factors in the CGRP^+/- rats comparing to the administration of (Dulbecco's Phosphate Buffered Saline) DPBS or peptide only. With the decrease of vascular wall thickness and the attenuation of the T cell infiltration in the lung, the polymer based CGRP delivery system showed potentials to facilitate the therapeutic effects of the CGRP which may help for the development of CGRP-based therapy in vascular and inflammatory disorder related diseases.

Keywords: CGRP; PLGA delivery; inflammatory and vascular disorders; nanoparticles; sustainable release.

Figure 1.

(A) TEM images, (B) diameter and (C) zeta-potentials of nanoparticles. Long term stability of the (D) diameter and (E) zeta-potential of nanoparticles in the water. (F) The sustained-release profile of CGRP from P-C NPs and PP-C NPs in the PBS under 37 °C for 120 h. (Mean ± SD, n = 3). (scale bar in magnified image, 100 nm).

Figure 2.

(A) Scheme of experiment design to investigate the function of CGRP loaded nanoparticles to modulate inflammatory and vascular factors in CGRP^+/− rats. (B) Concentration of the CGRP and other factors in serum post the administration in the CGRP^+/− rats comparing to the wild type. (Mean ± SEM, n = 3; *, p < .05; **, p < .01; ***, p < .001).

Figure 3.

(A) Hematoxylin-eosin (HE) staining and (B) CD3+ T cell immunohistochemistry staining of the lung sections after different treatments. The outer and inner surfaces of the blood vessels in (A) were outlined by the black dashed lines and the thicknesses of the vascular walls were indicated by the distances from the outer surfaces to the inner surfaces which were marked out by the black full lines.

Figure 4.

(A) Contents of CGRP and other factors in the lungs after the treatment of nanoparticles in the CGRP^+/− rats comparing to wild type rats. (B) mRNA expression of factors in the CGRP^+/− rats comparing to wild type rats post the treatments. (Mean ± SEM, n = 3; *, p < .05; **, p < .01, ****, p < .0001).