Lymph-Node-Targeted Drug Delivery for Effective Immunomodulation to Prolong the Long-Term Survival After Heart Transplantation

A novel FK506-loading mesoporous silica nanoparticle homing to lymph nodes for transplant rejection treatment

Tacrolimus (FK506) is an effective therapeutic for transplant rejection in clinical practice, primarily inhibiting rejection by suppressing the activation and proliferation of allogeneic T cells in the lymph nodes (LNs). However, conventional administration methods face challenges in directly delivering free FK506 to the LNs. In this study, we introduce a novel LN-targeted delivery system based on mesoporous silica nanoparticles (MSNs-FK506-MECA79). These particles were designed to selectively target high endothelial venules in LNs; this was achieved through surface modification with MECA79 antibodies. Their mean size and zeta potential were 201.18 ± 5.98 nm and - 16.12 ± 0.36 mV, respectively. Our findings showed that MSNs-FK506-MECA79 could accumulate in LNs and increase the local concentration of FK506 from 28.02 ± 7.71 ng/g to 123.81 ± 76.76 ng/g compared with the free FK506 treatment group. Subsequently, the therapeutic efficacy of MSNs-FK506-MECA79 was evaluated in a skin transplantation model. The treatment with MSNs-FK506-MECA79 could lead to a decrease in the infiltration of T cells in the grafts, a reduction in the grade of rejection, and a significant prolongation of survival. Consequently, this study presents a promising strategy for the active LN-targeted delivery of FK506 and improving the immunotherapeutic effects on transplant rejection.

Nanoparticle-assisted Targeting Delivery Technologies for Preventing Organ Rejection

Although organ transplantation is a life-saving medical procedure, the challenge of posttransplant rejection necessitates safe and effective immune modulation strategies. Nanodelivery approaches may have the potential to overcome the limitations of small-molecule immunosuppressive drugs, achieving efficacious treatment options for transplant tolerance without compromising overall host immunity. This review highlights recent advances in biomaterial-assisted formulations and technologies for targeted nanodrug delivery with transplant organ- or immune cell-level precision for treating graft rejection after transplantation. We provide an overview of the mechanism of transplantation rejection, current clinically approved immunosuppressive drugs, and their relevant limitations. Finally, we discuss the targeting principles and advantages of organ- and immune cell-specific delivery technologies. The development of biomaterial-assisted novel therapeutic strategies holds considerable promise for treating organ rejection and clinical translation.

Nanoparticle-based T cell immunoimaging and immunomodulatory for diagnosing and treating transplant rejection

T cells serve a pivotal role in the rejection of transplants, both by directly attacking the graft and by recruiting other immune cells, which intensifies the rejection process. Therefore, monitoring T cells becomes crucial for early detection of transplant rejection, while targeted drug delivery specifically to T cells can significantly enhance the effectiveness of rejection therapy. However, regulating the activity of T cells within transplanted organs is challenging, and the prolonged use of immunosuppressive drugs is associated with notable side effects and complications. Functionalized nanoparticles offer a potential solution by targeting T cells within transplants or lymph nodes, thereby reducing the off-target effects and improving the long-term survival of the graft. In this review, we will provide an overview of recent advancements in T cell-targeted imaging molecular probes for diagnosing transplant rejection and the progress of T cell-regulating nanomedicines for treating transplant rejection. Additionally, we will discuss future directions and the challenges in clinical translation.

Mitochondrion-targeted carboxymethyl chitosan hybrid nanoparticles loaded with Coenzyme Q10 protect cardiac grafts against cold ischaemia‒reperfusion injury in heart transplantation

BACKGROUND

Heart transplantation (HT) has been approved as an optimal therapeutic regimen for patients with terminal-stage cardiac failure. However, cold ischaemia‒reperfusion (I/R) injury remains an unavoidable and outstanding challenge, which is a major factor in early graft dysfunction and an obstacle to long-term survival in HT. Cold I/R injury induces cardiac graft injury by promoting mitochondrial dysfunction and augmenting free radical production and inflammatory responses. We therefore designed a mitochondrion-targeted nanocarrier loaded with Coenzyme Q10 (CoQ10) (CoQ10@TNPs) for treatment of cold I/R injury after cardiac graft in a murine heterotopic cardiac transplantation model.

METHODS

Hybrid nanoparticles composed of CaCO3/CaP/biotinylated-carboxymethylchitosan (CaCO3/CaP/BCMC) were synthesized using the coprecipitation method, and the mitochondria-targeting tetrapeptide SS31 was incorporated onto the surface of the hybrid nanoparticles through biotin-avidin interactions. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis were used for characterisation. In vitro, the hypoxia-reoxygenation model of H9c2 cells was employed to replicate in vivo cold I/R injury and treated with CoQ10@TNPs. The impact of CoQ10@TNPs on H9c2 cell injury was assessed by analysis of oxidative damage and apoptosis. In vivo, donor hearts (DHs) were perfused with preservation solution containing CoQ10@TNPs and stored in vitro at 4 °C for 12 h. The DHs were heterotopically transplanted and analysed for graft function, oxidative damage, apoptosis, and inflammatory markers 1 day post-transplantation.

RESULTS

CoQ10@TNPs were successfully synthesized and delivered CoQ10 to the mitochondria of the cold ischaemic myocardium. In vitro experiments demonstrated that CoQ10@TNPs was taken up by H9c2 cells at 4 °C and localized within the mitochondria, thus ameliorating oxidative stress damage and mitochondrial injury in cold I/R injury. In vivo experiments showed that CoQ10@TNPs accumulated in DH tissue at 4 °C, localized within the mitochondria during cold storage and improved cardiac graft function by attenuating mitochondrial oxidative injury and inflammation.

CONCLUSIONS

CoQ10@TNPs can precisely deliver CoQ10 to the mitochondria of cold I/R-injured cardiomyocytes to effectively eliminate mitochondrial reactive oxygen species (mtROS), thus reducing oxidative injury and inflammatory reactions in cold I/R-injured graft tissues and finally improving heart graft function. Thus, CoQ10@TNPs offer an effective approach for safeguarding cardiac grafts against extended periods of cold ischaemia, emphasizing the therapeutic potential in mitigating cold I/R injury during HT. These findings present an opportunity to enhance existing results following HT and broaden the range of viable grafts for transplantation.