Immunosuppressive nano-therapeutic micelles downregulate endothelial cell inflammation and immunogenicity

Abstract

In this study, we developed a stable, nontoxic novel micelle nanoparticle to attenuate responses of endothelial cell (EC) inflammation when subjected to oxidative stress, such as observed in organ transplantation. Targeted Rapamycin Micelles (TRaM) were synthesized using PEG-PE-amine and N-palmitoyl homocysteine (PHC) with further tailoring of the micelle using targeting peptides (cRGD) and labeling with far-red fluorescent dye for tracking during cellular uptake studies. Our results revealed that the TRaM was approximately 10 nm in diameter and underwent successful internalization in Human Umbilical Vein EC (HUVEC) lines. Uptake efficiency of TRaM nanoparticles was improved with the addition of a targeting moiety. In addition, our TRaM therapy was able to downregulate both mouse cardiac endothelial cell (MCEC) and HUVEC production and release of the pro-inflammatory cytokines, IL-6 and IL-8 in normal oxygen tension and hypoxic conditions. We were also able to demonstrate a dose-dependent uptake of TRaM therapy into biologic tissues ex vivo. Taken together, these data demonstrate the feasibility of targeted drug delivery in transplantation, which has the potential for conferring local immunosuppressive effects without systemic consequences while also dampening endothelial cell injury responses.

Effects of engineered nanoparticles on the innate immune system

“…For example, rapamycin-loaded poly (lactic-co-glycolic acid) (PLGA) NPs down-regulated intercellular adhesion molecule 1 (ICAM-1) expression in DCs and maintained DCs in the immature state, exhibiting an immunosuppressive response [89]. Rapamycin and dexamethasone loaded NPs also have been shown to downregulate production of pro-inflammatory cytokines via sustained drug release, maintaining immunosuppression to transplant recipients, and prolonging viability of transplanted tissue [90,91]. In many autoimmune diseases, the expression of pro-inflammatory cytokines is overwhelming.…”

Nanotechnological Approaches to Immunosuppression and Tolerance Induction

“…We demonstrated that membrane targeting facilitated receptor mediated micelle endocytosis, and significantly enhanced micellular specific uptake, as compared to untargeted constructs in in-vitro models. Further, we showed that rapamycin micelles inhibited EC cytokine production, and alloreactive T cell proliferation, as compared to free rapamycin drug or untargeted rapamycin micelles 68 . Finally, we were able to demonstrate that incorporation of cRGD targeting moiety to the micelle construct improved aortic graft uptake as compared to untargeted constructs when micelles were added to University of Wisconsin solution ex-vivo.…”

“…Although, these studies set the stage for donor organ pre-treatment, the methods employed are not clinically translatable and therefore strategies to target rapamycin to donor ECs pre-transplantation offer promise for improving post-transplant outcomes. To this end, we have recently designed and constructed rapamycin micelles decorated with cyclic arginine-glycine-aspartate moieties (cRGD) specific for alpha V beta 3 (αVβ3) integrins located on the surface of endothelial cells 68 . We demonstrated that membrane targeting facilitated receptor mediated micelle endocytosis, and significantly enhanced micellular specific uptake, as compared to untargeted constructs in in-vitro models.…”

Organ preservation with targeted rapamycin nanoparticles: a pre-treatment strategy preventing chronic rejection in vivo

“…Therefore, in this study, we report the application of our novel TRaM nanoparticles as an additive to UW and explore the impact of donor organ nanoparticle delivered rapamycin on the development of chronic rejection 9. For the first time, we show that donor organ pre-treatment with TRaM augmented UW preservation solution, as compared to standard-of-care UW alone and UW augmented with free rapamycin, protects against the development of chronic rejection in two separate in vivo allograft models.…”