Delivery Of Rapamycin Research Articles

Adhesive polyelectrolyte coating on PLGA particles prolongs drug retention to vessel lesion.

Restenosis, the re-narrowing of blood vessels after drug-coated balloons (DCBs), remains a major clinical issue. While rapamycin is the current clinical option for preventing restenosis due to its effectiveness and low toxicity, its delivery is limited by poor tissue absorption and rapid clearance, leading to suboptimal drug retention. Here, we developed the adhesive-polyelectrolyte-coated poly(lactic-co-glycolic acid) (PLGA) particles using in-situ UV-triggered polymerization, encapsulating rapamycin. This system combines PLGA's sustained release with a robust adhesive coating that enhances vascular wall binding, by hydrogen bonding and covalent bonding. Rapamycin retention improved by 835 % in vitro (1 week) and 525 % in vivo (4 weeks) compared to uncoated particles. This approach offers a promising strategy to enhance rapamycin delivery, improving the safety and efficacy of DCBs in treating vessel obstruction.

PEGylated iron oxide-gold core-shell nanoparticles for tumor-targeted delivery of Rapamycin.

Rapamycin analogs are approved by the FDA for breast and renal cancer treatment. Hence, the possibility of nanoparticle-mediated delivery ofRapamycin could be examined. In the present study, PEGylated Gold-core shell iron oxide nanoparticles were used for the targeted delivery of Rapamycin, and R-Au-IONPs were formulated. SEM, XRD, and FTIR determined the smooth spherical morphology, andcompositional structure, and confirmed the conjugation of Rapamycin onto the NPs. The in vitro drug release study showed acontrolled release of the drug over time. R-Au-IONPs showed significant cytotoxicity in MCF 7 cells. Anti-proliferative assays such as trypan blue dye exclusion assay, microscopy, Fluorescent staining, and clonogenic assays were performed. NH staining, Rhodamine 123 staining, PS externalization, and the cleavage of PARP protein by western immunoblot assays confirmed the induction of apoptosis. The mechanism of R-Au-IONP-induced cell death was analyzed by flow cytometry. Our in-vitro study, on the impact of R-Au-IONPs on cell viability in the human breast adenocarcinoma cell line (MCF-7), confirms the efficacy of drug delivery using the nanoparticle system. Further results implied the induction of apoptosis. This drug delivery system using Rapamycin could be a potential candidate in the treatment of breast cancer.

Scanning Transmission Soft X-Ray Microscopy Probes Topical Drug Delivery of Rapamycin Facilitated by Microneedles.

Scanning Transmission X-ray microscopy (STXM) is a sensitive and selective probe for the penetration of rapamycin which is topically applied to human skin ex vivo and is facilitated by skin treatment with microneedles puncturing the skin. Inner-shell excitation serves as a selective probe for detecting rapamycin by changes in optical density as well as linear combination modeling using reference spectra of the most abundant species. The results indicate that mechanical damage induced by microneedles allows this drug to accumulate in the stratum corneum without reaching the viable skin layers. This is unlike intact skin which shows no drug penetration at all and underscores the mechanical impact of microneedle skin treatment. These results are compared to drug penetration profiles of other drugs highlighting the importance of skin barriers. High spatial resolution studies also indicate that the lipophilic drug rapamycin is observed in corneocytes. Attempts in data evaluation are reported to probe rapamycin also in the lipid layers between the corneocytes, which was not accomplished before. These results are compared to recent results on rapamycin uptake in skin where barrier impairment was induced by pre-treatment with the enzyme trypsin and drug formulations leading to occlusion.

Safety Evaluations of Rapamycin Perfluorocarbon Nanoparticles in Ovarian Tumor-Bearing Mice.

Nanomedicine holds great potential for revolutionizing medical treatment. Ongoing research and advancements in nanotechnology are continuously expanding the possibilities, promising significant advancements in healthcare. To fully harness the potential of nanotechnology in medical applications, it is crucial to conduct safety evaluations for the nanomedicines that offer effective benefits in the preclinical stage. Our recent efficacy studies indicated that rapamycin perfluorocarbon (PFC) nanoparticles showed promise in mitigating cisplatin-induced acute kidney injury (AKI). As cisplatin is routinely administered to ovarian cancer patients as their first-line chemotherapy, in this study, we focused on evaluating the safety of rapamycin PFC nanoparticles in mice bearing ovarian tumor xenografts. Specifically, this study evaluated the effects of repeat-dose rapamycin PFC nanoparticle treatment on vital organs, the immune system, and tumor growth and assessed pharmacokinetics and biodistribution. Our results indicated that rapamycin PFC nanoparticle treatment did not cause any detectable adverse effects on cardiac, renal, or hepatic functions or on splenocyte populations, but it reduced the splenocyte secretion of IL-10, TNFα, and IL12p70 upon IgM stimulation. The pharmacokinetics and biodistribution results revealed a significant enhancement in the delivery of rapamycin to tumors by rapamycin PFC nanoparticles, which, in turn, led to a significant reduction in ovarian tumor growth. Therefore, rapamycin PFC nanoparticles have the potential to be clinically beneficial in cisplatin-treated ovarian cancer patients.

Nano-based perivascular intervention sustains a nine-month long-term suppression of intimal hyperplasia in vein grafts

Open vascular reconstructions (OVR), including bypass grafts and dialysis access, are standard treatments for cardiovascular and renal diseases. Unfortunately, OVR often fail largely due to intimal hyperplasia (IH), and there are no clinical methods to prevent this complication. Perivascular drug administration during OVR presents a promising strategy for IH suppression. However, durations of drug release from carriers are generally short whereas sustained efficacy is essential for clinical success. This raises a critical question in clinical translation: can IH suppression be realistically maintained long-term (e.g., over 6 months) with short-term perivascular interventions? To address this question, we modified a rat vein-graft model to prolong IH progression. We then applied Pericelle, a nanoparticle/hydrogel hybrid system that we developed for perivascular delivery of rapamycin, an established IH-inhibitory drug. Surprisingly, despite short (∼3-month) drug release, Pericelle demonstrated IH suppression throughout 3, 6, and 9 months with IH reduced from 115.58 ± 27.89 to 40.34 ± 5.18 at 9 months (P < 0.05, n = 6 rats), as indicated by morphometric analysis. Live animal ultrasonography showed the same trend. Consistently, histone-3 lysine-27 trimethylation, an epigenetic mark associated with IH progression, was decreased at 6 months after Pericelle treatment. Moreover, Pericelle exhibited promising efficacy in mitigating IH in a porcine model of arteriovenous fistula that mimics dialysis access. These results suggest that Pericelle-mediated suppression of IH in rat vein-grafts extends much beyond drug release, offering potential solutions to longstanding translational challenges in reducing OVR failure.

Targeted Rapamycin Delivery via Magnetic Nanoparticles to Address Stenosis in a 3D Bioprinted in Vitro Model of Pulmonary Veins.

Vascular cell overgrowth and lumen size reduction in pulmonary vein stenosis (PVS) can result in elevated PV pressure, pulmonary hypertension, cardiac failure, and death. Administration of chemotherapies such as rapamycin have shown promise by inhibiting the vascular cell proliferation; yet clinical success is limited due to complications such as restenosis and off-target effects. The lack of in vitro models to recapitulate the complex pathophysiology of PVS has hindered the identification of disease mechanisms and therapies. This study integrated 3D bioprinting, functional nanoparticles, and perfusion bioreactors to develop a novel in vitro model of PVS. Bioprinted bifurcated PV constructs are seeded with endothelial cells (ECs) and perfused, demonstrating the formation of a uniform and viable endothelium. Computational modeling identified the bifurcation point at high risk of EC overgrowth. Application of an external magnetic field enabled targeting of the rapamycin-loaded superparamagnetic iron oxide nanoparticles at the bifurcation site, leading to a significant reduction in EC proliferation with no adverse side effects. These results establish a 3D bioprinted in vitro model to study PV homeostasis and diseases, offering the potential for increased throughput, tunability, and patient specificity, to test new or more effective therapies for PVS and other vascular diseases.

Delivery of rapamycin by biomimetic peptide nanoparticles targeting oxidized low-density lipoprotein in atherosclerotic plaques.

Drug delivery systems based on biomimetic peptide nanoparticles are steadily gaining prominence in the treatment of diverse medical conditions. This study focused on the development of peptides that depend on ligand-receptor interactions to load rapamycin (RAPA). Furthermore, a multifunctional peptide was engineered to target oxidized low-density lipoprotein (oxLDL) within atherosclerotic plaques, facilitating the localized delivery of RAPA. The interactions between peptides and RAPA/oxLDL were analyzed by simulations and experimental approaches. Results show that the main amino acid residues on the mammalian target of rapamycin that bind to RAPA are constructed as peptides (P1 and P2), which have specific interactions with RAPA and can effectively improve the loading efficiency of RAPA. The encapsulation and drug loading efficiencies of P1/P2 were 68.0/47.9% and 48.3/36.5%, respectively. In addition, the interaction force of the multifunctional peptide (P3) and oxLDL surpassed that of their interaction with human umbilical vein endothelial cells by a factor of 3.6, conclusively establishing the specific targeting of oxLDL by these nanoparticles. The encapsulation and drug loading efficiencies of P3 for RAPA were determined to be 60.2% and 41.5%. P3 can effectively load RAPA and target oxLDL within the plaque, suggesting that P3 has potential as a therapeutic agent for atherosclerotic disease.

Biomimetic nanoparticles with enhanced rapamycin delivery for autism spectrum disorder treatment via autophagy activation and oxidative stress modulation.

Rationale: Autism spectrum disorder (ASD) represents a complex neurodevelopmental condition lacking specific pharmacological interventions. Given the multifaced etiology of ASD, there exist no effective treatment for ASD. Rapamycin (RAPA) can activate autophagy by inhibiting the mTOR pathway and has exhibited promising effects in treating central nervous system disorders; however, its limited ability to cross the blood-brain barrier (BBB) has hindered its clinical efficacy, leading to substantial side effects. Methods: To address this challenge, we designed a drug delivery system utilizing red blood cell membrane (CM) vesicles modified with SS31 peptides to enhance the brain penetration of RAPA for the treatment of autism. Results: The fabricated SCM@RAPA nanoparticles, with an average diameter of 110 nm, exhibit rapid release of RAPA in a pathological environment characterized by oxidative stress. In vitro results demonstrate that SCM@RAPA effectively activate cellular autophagy, reduce intracellular ROS levels, improve mitochondrial function, thereby ameliorating neuronal damage. SS31 peptide modification significantly enhances the BBB penetration and rapid brain accumulation of SCM@RAPA. Notably, SCM@RAPA nanoparticles demonstrate the potential to ameliorate social deficits, improve cognitive function, and reverse neuronal impairments in valproic acid (VPA)-induced ASD models. Conclusions: The therapeutic potential of SCM@RAPA in managing ASD signifies a paradigm shift in autism drug treatment, holding promise for clinical interventions in diverse neurological conditions.

Abstract 13842: A Macromolecule-Linked Prodrug of Rapamycin Shows Potent Growth Inhibitory Effects Against Activated Fibroblasts Mimicking Fibroproliferative Transformation in Pulmonary Hypertension

Introduction: Pulmonary hypertension (PH) is a life-threatening disease characterized by a progressive loss of vascular cell homeostasis with an irreversible shift toward the activated proliferative phenotype. New drug delivery approaches with improved efficacy are urgently needed for better clinical management of the disease. The present studies evaluated a novel prodrug-based strategy designed to durably suppress PH through enhanced delivery of rapamycin. We hypothesized that a long-circulating rapamycin prodrug constructed with a bioeliminable polyethylene glycol (PEG) scaffold would show efficacy as a new anti-PH drug candidate in cell culture and animal model studies. Methods: A new carrier-linked prodrug was synthesized by reversibly attaching rapamycin to 4-arm PEG (PEG-[RAPA] 4 , Mn = 40 kDa). Cell growth inhibitory effects of the construct were studied in vitro with proliferative fetal lung fibroblasts (HEL299) and transformed fibroblast-type cells (SK-LMS1), and in vivo using SK-LMS1 xenografts established in athymic nude mice. The results were analyzed by comparing the growth curve slopes (one-way ANOVA with the Tukey post hoc test). Results: Rapamycin (1-5 μM) potently inhibited proliferation of both fetal and transformed fibroblasts (75-95% inhibition 7 days post-treatment) in PDGF-BB-stimulated growth conditions (40 ng/ml, 2% FBS). Serum-stimulated (10% FBS) growth of both cell lines was also suppressed with remarkable potency at all tested concentrations (≥50% and ≥65% inhibition for HEL299 and SK-LMS1, respectively). In animal model studies, PEG-[RAPA] 4 given 2х/week strongly mitigated disease progression throughout the 4-week treatment period, whereas all animals in ‘no treatment’ and ‘blank PEG’ control groups were eliminated after reaching the end point. Statistical analysis confirmed markedly delayed growth of SK-LMS1 xenografts in the prodrug group (p = 0.032). Conclusions: Polymeric carrier-linked prodrug delivery of rapamycin effectively inhibits growth of activated fibroblasts in vitro and in a preclinical model recapitulating the altered vascular cell phenotype and proliferative character of the human disease. PEG-[RAPA] 4 is a promising candidate for further evaluation as a potential therapy for PH.

Exploring the translational potential of PLGA nanoparticles for intra-articular rapamycin delivery in osteoarthritis therapy

Osteoarthritis (OA) is a prevalent joint disease that affects all the tissues within the joint and currently lacks disease-modifying treatments in clinical practice. Despite the potential of rapamycin for OA disease alleviation, its clinical application is hindered by the challenge of achieving therapeutic concentrations, which necessitates multiple injections per week. To address this issue, rapamycin was loaded into poly(lactic-co-glycolic acid) nanoparticles (RNPs), which are nontoxic, have a high encapsulation efficiency and exhibit sustained release properties for OA treatment. The RNPs were found to promote chondrogenic differentiation of ATDC5 cells and prevent senescence caused by oxidative stress in primary mouse articular chondrocytes. Moreover, RNPs were capable to alleviate metabolism homeostatic imbalance of primary mouse articular chondrocytes in both monolayer and 3D cultures under inflammatory or oxidative stress. In the mouse destabilization of the medial meniscus (DMM) model, intra-articular injection of RNPs effectively mitigated joint cartilage destruction, osteophyte formation, chondrocytes hypertrophy, synovial inflammation, and pain. Our study demonstrates the feasibility of using RNPs as a potential clinically translational therapy to prevent the progression of post-traumatic OA.Graphical abstract

The role of glycerol–water mixtures in the stability of FKBP12-rapalog-FRB complexes

The thermodynamic and biophysical implications of the introduction of a co-solvent during protein-ligand binding remain elusive. Using ternary complexes of 12-kDa FK506 binding protein (FKBP12), FKBP-rapamycin binding (FRB) domain of the mammalian/mechanistic target of rapamycin (mTOR) kinase, and rapamycin analogs (rapalogs) in glycerol–water mixtures, the influence of solvent composition on ligand binding dynamics was explored. The pharmaceutical potential of rapalogs and the utility of glycerol as a co-solvent in drug delivery applications were critical in deciding the system to be studied. Consolidation of existing studies on rapamycin modification was first performed to strategically design a new rapalog called T1. The results from 100-ns dual-boost Gaussian accelerated molecular dynamics simulations showed that protein stability was induced in the presence of glycerol. Reweighting of the trajectories revealed that the glycerol-rich solvent system lowers the energy barrier in the conformational space of the protein while also preserving native contacts between the ligand and the residues in the binding site. Calculated binding free energies using MM/GBSA also showed that electrostatic energy and polar contribution of solvation energy are heavily influenced by the changes in solvation. Glycerol molecules are preferentially excluded through electrostatic interactions from the solvation shell which induce complex stability as seen in existing experiments. Hence, using glycerol as a co-solvent in rapamycin delivery has a significant role in maintaining stability. In addition, compound T1 is a potential mTORC1-selective inhibitor with strong affinity for the FKBP12-FRB complex. This study aims to provide insights on the design of new rapalogs, and the applicability of glycerol as co-solvent for FKBP12-rapalog-FRB complexes.

Silica nanocarrier-mediated intracellular delivery of rapamycin promotes autophagy-mediated M2 macrophage polarization to regulate bone regeneration

Targeting macrophages to regulate the immune microenvironment is a new strategy for bone regeneration with nano-drugs. Nano-drugs have achieved surprising anti-inflammatory and bone-regenerative effects, however, their underlying mechanisms in macrophages remain to be clarified. Macrophage polarization, immunomodulation, and osteogenesis are governed by autophagy. Rapamycin, an autophagy inducer, has shown promising results in bone regeneration, but high dose-mediated cytotoxicity and low bioavailability hinder its clinical application. This study aimed to develop rapamycin-loaded virus-like hollow silica nanoparticles (R@HSNs) which are easily phagocytosed by macrophages and translocated to lysosomes. R@HSNs induced macrophage autophagy, promoted M2 polarization, and alleviated the degree of M1 polarization as indicated by the downregulation of inflammatory factors IL-6, IL-1β, TNF-α, and iNOS, and upregulation of anti-inflammatory factors CD163, CD206, IL-1ra, IL-10, and TGF-β. These effects were nullified by cytochalasin B-induced inhibition of R@HSNs uptake in macrophages. The conditioned medium (CM) collected from R@HSNs-treated macrophages promoted osteogenic differentiation of mouse bone marrow mesenchymal stromal cells (mBMSCs). In a mouse calvaria defect model, free rapamycin treatment was inhibited, but R@HSNs robustly promoted bone defect healing. In conclusion, silica nanocarrier-mediated intracellular rapamycin delivery to macrophages effectively triggers autophagy-mediated M2 macrophage polarization, further enhancing bone regeneration by triggering osteogenic differentiation of mBMSCs.

Nanoparticle cluster depolymerizes and removes amyloid fibrils for Alzheimer’s disease treatment

Aberrant amyloid-β (Aβ) fibrillation is the key event in Alzheimer’s disease (AD), the depolymerization and removal of which are being pursued with enthusiasm. Herein, a nanoparticle cluster is designed for amyloid-matching based on point-to-point strategy to prevent amyloid fibrillation. After reaching AD nidus, this cluster decomposes into ultra-small nanoparticles, and exposes more binding sites in different types to match with Aβ sequence via multivalent binding. Notably, AD microenvironment sensitive nucleophilic substitution reaction generates strong covalent linkage between nanoparticle and amyloid, which ensures high binding specificity/affinity. The strong binding event competitively reduces amyloid-amyloid interactions thereby disintegrating amyloid fibrils. Not only that, monomeric Aβ after fibrils depolymerization and nanoparticles reassemble into nanoparticle&Aβ composite. Such composite realizes Aβ receptor mediated precise rapamycin delivery into microglia, further normalizing microglial immunologic dysfunction for Aβ removal and brain-friendly environment. This system interferes with amyloid fate, rescues memory deficits in AD.

Transferrin decorated-nanostructured lipid carriers (NLCs) are a promising delivery system for rapamycin in Alzheimer's disease: An in vivo study.

Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by progressive cognitive impairment and memory loss. The mammalian target of rapamycin (mTOR) signaling pathway could regulate learning and memory. The effect of rapamycin (Rapa) on mTOR activity could slow or prevent the progression of AD by affecting various essential cellular processes. Previously, we prepared transferrin (Tf) decorated-nanostructured lipid carriers (NLCs) for rapamycin (150±9nm) to protect the drug from chemical and enzymatic degradation and for brain targeted delivery of rapamycin. Herein, the effect of Tf-NLCs compared to untargeted anionic-NLCs and free rapamycin, were studied in amyloid beta (Aβ) induced rat model of AD. Behavioral test revealed that the Rapa Tf-NLCs were able to significantly improve the impaired spatial memory induced by Aβ. Histopathological studies of hippocampus also showed neural survival in Rapa Tf-NLCs treated group. The immunosuppressive, and delayed wound healing adverse effects in the rapamycin solution treated group were abolished by incorporating the drug into NLCs. The Aβ induced oxidative stress was also reduced by Rapa Tf-NLCs. Molecular studies on the level of Aβ, autophagy (LC3) and apoptotic (caspase-3) markers, and mTOR activity revealed that the Rapa Tf-NLCs decreased the Aβ level and suppressed the toxic effects of Aβ plaques by modulating the mTOR activity and autophagy, and decreasing the apoptosis level. As a conclusion, the designed Tf-NLCs could be an appropriate and a safe brain delivery system for rapamycin and make this drug more efficient in AD for improving memory and neuroprotection.

The topical ocular delivery of rapamycin to posterior eye tissues and the suppression of retinal inflammatory disease

Treatment of posterior eye diseases with intravitreal injections of drugs, while effective, is invasive and associated with side effects such as retinal detachment and endophthalmitis. In this work, we have formulated a model compound, rapamycin (RAP), in nanoparticle-based eye drops and evaluated the delivery of RAP to the posterior eye tissues in a healthy rabbit. We have also studied the formulation in experimental autoimmune uveitis (EAU) mouse model with retinal inflammation. Aqueous RAP eye drops were prepared using N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (Molecular Envelope Technology – MET) containing 0.23 ± 0.001% w/v RAP with viscosity, osmolarity, and pH within the ocular comfort range, and the formulation (MET-RAP) was stable in terms of drug content at both refrigeration and room temperature for one month. The MET-RAP eye drops delivered RAP to the choroid-retina with a Cmax of 145 ± 49 ng/g (tmax = 1 h). The topical application of the MET-RAP eye drops to the EAU mouse model resulted in significant disease suppression compared to controls, with activity similar to dexamethasone eye drops. The MET-RAP eye drops also resulted in a reduction of RORγt and an increase in both Foxp3 expression and IL-10 secretion, indicating a mechanism involving the inhibition of Th17 cells and the up-regulation of T-reg cells. The MET-RAP formulation delivers RAP to the posterior eye segments, and the formulation is active in EAU.

Therapeutic Effect of Rapamycin-Loaded Small Extracellular Vesicles Derived from Mesenchymal Stem Cells on Experimental Autoimmune Uveitis.

Autoimmune uveitis is a major cause of vision loss and glucocorticoids are major traditional medications, which may induce serious complications. Rapamycin has been demonstrated to exhibit immunosuppressive effects and is promising to be used in treating uveitis by intravitreal injection. However, repeated and frequent intravitreal injections increase the risk of severe ocular complications, while the efficacy of subconjunctival injection of rapamycin is low since it is difficult for rapamycin to penetrate eyeball. Recently, small extracellular vesicles (sEVs) have attracted considerable research interest as natural drug delivery systems that can efficiently cross tissues and biological membranes. SEVs derived from mesenchymal stem cells (MSC-sEVs) also can exert immunosuppressive effect and ameliorate experimental autoimmune uveitis (EAU). The aim of this study was to construct a Rapamycin-loaded MSC-sEVs delivery system (Rapa-sEVs) and investigate its therapeutic effect on EAU by subconjunctival injection. Rapa-sEVs were prepared by sonication and characterized by nanoparticle tracking analysis, transmission electron microscopy, and western blotting. Clinical and histological scores were obtained to assess the treatment efficacy. Additionally, T cell infiltration was evaluated by flow cytometry. The results indicated that Rapa-sEVs could reach the retinal foci after subconjunctival injection. Compared to sEVs and rapamycin alone, Rapa-sEVs can produce a more marked therapeutic effect and reduce ocular inflammatory cell infiltration. Overall, MSC-sEVs have significant potential for the delivery of rapamycin to treat EAU. Subconjunctival injection of Rapa-sEVs may be contender for efficacious steroid-sparing immunomodulatory therapy.

Ultrasound-mediated rapamycin delivery for promoting osseointegration of 3D printed prosthetic interfaces via autophagy regulation in osteoporosis

Osteoporosis-derived bone marrow mesenchymal stem cells (OP-BMSCs) have impaired cell function, low osteogenic activity, and potential osteoclast inducibility, resulting in insufficient osseointegration and increased risk of catastrophic postoperative complications after arthroplasty. The low autophagy activity of OP-BMSCs contributed to poor osseointegration, which could be regulated by the classical autophagic activator, rapamycin. Hence, it is of great significance to regulate autophagy by rapamycin to promote osseointegration at the three-dimensional (3D) printed prosthetic interfaces under osteoporotic environment. In this study, 3D printed porous titanium alloy prosthetic interfaces with bionic pore size and porosity were prepared and implanted into the distal femur of osteoporosis rabbits. Subsequently, a transdermal drug delivery device was used to deliver rapamycin to the interfaces implantation sites. Ultrasound-mediated rapamycin delivery could restore the declined cellular activities (including cell viability, proliferation, migration, and osteogenesis), as well as inhibit potential osteoclast-inducing capacity and adipogenic differentiation by upregulating the autophagy level of OP-BMSCs. Moreover, percutaneous ultrasound-mediated rapamycin delivery significantly improved bone ingrowth and osseointegration of prosthetic interfaces in osteoporotic environment. To conclude, this novel therapy combining 3D printed bionic prosthesis and percutaneous ultrasound-mediated rapamycin delivery can effectively promote prosthetic interfaces osseointegration by regulating autophagy after arthroplasty for patients with osteoporosis.

Development of rapamycin-encapsulated exosome-mimetic nanoparticles-in-PLGA microspheres for treatment of hemangiomas

We have previously developed several kinds of rapamycin-encapsulated nanoparticles to achieve sustained release of rapamycin to treat hemangioma. However, lack of intrinsic targeting and easy clearance by the immune system are major hurdles that artificial fabricated nanoparticles must overcome. We constructed rapamycin-encapsulated macrophage-derived exosomes mimic nanoparticles-in-microspheres (RNM), to achieve the goal of continuous targeted therapy of hemangiomas. The rapamycin-encapsulated exosome mimic nanoparticles (RN) were firstly prepared by the extrusion-based method from the U937 cells (the human macrophage cell line). After then, RN was encapsulated with PLGA (poly(lactic-co-glycolic acid)) microspheres to obtain RNM. The release profile, targeting activity, and biological activity of RN and RNM were investigated on hemangioma stem cells (HemSCs). RN has a size of 100 nm in diameter, with a rapamycin encapsulation efficacy (EE) of 83%. The prepared microspheres RNM have a particle size of ~30 µm), and the drug EE of RNM is 34%. The sustained release of RNM can remarkably be achieved for 40 days. As expected, RN and RNM showed effective inhibition of cellular proliferation, significant cellular apoptosis, and remarkable repressed expression of angiogenesis factors in HemSCs. Our results showed that RNM is an effective approach for prolonged and effective delivery of rapamycin to hemangiomas.

Microenvironment-activatable cascaded responsive carbonized polymer dots as a theranostic platform for precise rapamycin delivery to potentiate the synergy of chemotherapy and γδ T cells-mediated immunotherapy against tumor

The combination of chemotherapy and immunotherapy (also known as chemo/immunotherapy) promoted by nanomedicine has the potential to enhance the therapeutic effect in more patient populations. However, it is still affected by the inactivation of immune cells induced by traditional chemotherapy, which greatly impairs the synergistic effect of chemotherapy/immunotherapy substantially. Moreover, once tumor cells lose their MHC expression, the current popular CD8+ T cell-based immunotherapy may fail consequently. Herein, rapamycin, as mTOR signaling inhibitor associated with serious side effect once systemically administered, was incorporated into shell-core theranostic nanoplatform to augment synergy of chemotherapy and γδ T cell-mediated MHC-unrestricted immunotherapy against tumor without toxicity on γδ T cells. This nano-platform assembled from a cleavable shell and a carbonized polymer dot core can achieve accurate delivery of rapamycin with traceable imaging and cascade response. Such cascaded responsiveness has endowed it with improved blood compatibility, effective tumor accumulation, microenvironment-selective endocytosis, and hierarchical drug release facilitated by microenvironment-triggered programmable properties (size shrinkage, charge conversion and degradability) transition responding to blood-tissue-cells multi-level biological barriers. In vitro and in vivo experiments have shown that the nanoplatform not only promotes tumor chemotherapy by down-regulating mTOR signals, but also enhances γδ T cell-mediated immunotherapy by promoting the NKG2D pathway in a microenvironment-selective manner. In addition, the TCR-δ knockout mouse model was used to verify the synergy of chemical/immunotherapy promoted by the nanoplatform. In addition to multifunctional integrated therapeutic and diagnostic strategies, we also provide a paradigm to enhance the synergistic effect of chemotherapy/immunotherapy, and broaden the horizons of immunotherapy through γδ T cell-mediated replacement therapy assisted by nano-drugs.

Brain targeted delivery of rapamycin using transferrin decorated nanostructured lipid carriers.

Introduction: Recent studies showed that rapamycin, as a mammalian target of rapamycin (mTOR) inhibitor, could have beneficial therapeutic effects for the central nervous system (CNS) related diseases. However, the immunosuppressive effect of rapamycin as an adverse effect, the low water solubility, and the rapid in vivo degradation along with the blood-brain barrier-related challenges restricted the clinical use of this drug for brain diseases. To overcome these drawbacks, a transferrin (Tf) decorated nanostructured lipid carrier (NLC) containing rapamycin was designed and developed. Methods: Rapamycin-loaded cationic and bare NLCs were prepared using solvent diffusion and sonication method and well characterized. The optimum cationic NLCs were physically decorated with Tf. For in vitro study, the MTT assay and intracellular uptake of nanoparticles on U-87 MG glioblastoma cells were assessed. The animal biodistribution of nanoparticles was evaluated by fluorescent optical imaging. Finally, the in vivo effect of NLCs on the immune system was also studied. Results: Spherical NLCs with small particle sizes ranging from 120 to 150 nm and high entrapment efficiency of more than 90%, showed ≥80% cell viability. More importantly, Tf-decorated NLCs in comparison with bare NLCs, showed a significantly higher cellular uptake (97% vs 60%) after 2 hours incubation and further an appropriate brain accumulation with lower uptake in untargeted tissue in mice. Surprisingly, rapamycin-loaded NLCs exhibited no immunosuppressive effect. Conclusion: Our findings proposed that the designed Tf-decorated NLCs could be considered as a safe and efficient carrier for targeted brain delivery of rapamycin which may have an important value in the clinic for the treatment of neurological disorders.