Platelet membrane-based and tumor-associated platelet- targeted drug delivery systems for cancer therapy

Abstract

Platelets have long been known to play critical roles in hemostasis by clumping and clotting blood vessel injuries. Recent experimental evidence strongly indicates that platelets can also interact with tumor cells by direct binding or secreting cytokines. For example, platelets have been shown to protect circulating cancer cells in blood circulation and to promote tumor metastasis. In-depth understanding of the role of platelets in cancer progression and metastasis provides promising approaches for platelet biomimetic drug delivery systems and functional platelet-targeting strategies for effective cancer treatment. This review highlights recent progresses in platelet membrane-based drug delivery and unique strategies that target tumor-associated platelets for cancer therapy. The paper also discusses future development opportunities and challenges encountered for clinical translation.

Keywords

platelet-mimicking delivery systems / tumor-associated platelets / cancer therapy / EPR effect

Introduction

Aside from playing important roles in thrombus formation and wound repair [¹,²], platelets maintain tumor blood vessel integrity and promote tumor metastasis [³,⁴]. To utilize the natural pathophysiological affinity and targeting ability of platelets to tumors, biomimetic and biocompatible drug delivery systems based on platelet membrane, genetically engineered platelet membranes or hybrid platelet membranes loaded with organic or inorganic biomaterials, and drug delivery systems have been generated for various drug delivery applications and cancer therapy. In addition, tumor-associated platelets are specific therapeutic targets in the design and fabrication of anticancer drug delivery systems. Significantly, improved antitumor efficacy has been reported in various drug delivery systems, such as nanomedicinal systems. In this review, we will first describe seminal works describing exploitation of platelet membrane as key component in tumor targeting and therapeutic drug delivery. We will then discuss recent progresses on the design and fabrication of tumor-associated platelet-targeting drug delivery systems and opportunities and challenges for platelet-based cancer therapy.

Platelet membrane-based nanoformulations for antitumor drug delivery

Whether in circulation or in tumor microenvironment, platelet–tumor cell interactions [⁵–⁷] have inspired the generation of several platelet-based drug delivery systems, including solely natural or genetically engineered platelet membrane-based drug delivery systems and platelet membrane-coated drug delivery systems. Systems based on core components of platelet membrane have been divided into two categories, namely, organic bioinspired drug delivery systems and inorganic bioinspired drug delivery systems. In the succeeding sections, we have summarized recent advancements in platelet membrane-based drug delivery systems. Fig.1 illustrates the prevailing design scheme of platelet membrane-based drug delivery systems.

Natural and genetically engineered platelet membranes for antitumor drug delivery

Entire platelet membranes or genetically engineered platelet membranes are used as drug delivery vehicles to completely mimic platelet features. Ouyang’s group first utilized natural platelet membranes as a carrier to deliver chemotherapeutic drugs (doxorubicin, Dox) to treat lymphoma (Fig. 2) [⁸].

In vitro investigations by using scanning electron microscopy and Western blot characterization of Dox-loaded platelets demonstrated that platelet membranes remained intact with their characteristic bioactive molecules after drug loading. The present study’s in vivo antitumor experiments and safety evaluation showed that Dox-loaded platelets significantly inhibited tumor growth while exhibiting good biocompatibility, biodegradability, and immune system evasion. Previous studies have shown that platelets preferentially accumulate not only in wound sites but also around circulating tumor cells (CTCs) [⁹,¹⁰]. Based on these intrinsic properties of platelets, Gu’s group developed an engineered monoclonal antibodies against programmed-death ligand 1 (anti-PD-L1)-coated platelet drug delivery system to block tumor post-surgical recurrence and metastasis (Fig. 3A) [¹¹].

Conjugation of anti-PD-L1 with platelets prolonged the half-life of anti-PD-L1 from 5 to 35 h. When the engineered immunoplatelet conjugates reached the surgical site or attached to CTCs, the platelets were activated and efficiently released anti-PD-L1-containing platelet microparticles (PMPs) which induced tumor cell death by immunological approach. In vivo imaging indicated that the engineered anti-PD-L1 immunoplatelet conjugates aggregated in the post-surgical site to an amount 10-fold higher than that of free anti-PD-L1 antibody. Two high-metastatic animal models, namely, melanoma (B16-F10) and triple-negative breast carcinoma (4T1), were established to examine antirecurrence and antimetastasis activities of antiPD-L1 immunoplatelet conjugates. As shown in Fig. 3B, platelet-conjugated anti-PD-L1 significantly reduced risks of cancer recurrence and metastases after surgery. Platelets are anuclear cytoplasmic bodies that detach from megakaryocytes in the bone marrow [¹²]. By using genetic modification of platelet membrane proteins in megakaryocytes, King’s group constructed platelets expressing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) (Fig. 4) [¹³]. In vitro experiments indicated that the platelets can significantly target tumor cells and induce apoptosis. In vivo, the genetically engineered platelets significantly reduced liver metastases.

Platelet-membrane-shell drug delivery system

Biological membrane coating has endowed biocompatibility and some special physiological properties to engineered nanocarriers. Inspired by the function of platelets as sentinels for vascular damage and invading microorganisms, Zhang’s group designed a platelet membrane-coated polymer nanoparticles (PNPs) consisting of a polymer core and a platelet membrane shell (Fig. 5) [¹⁴].

These PNPs possess several inherent platelet properties, including immunocompatibility, binding ability to injured vasculature, and pathogen adhesion. Development of large-scale purification and dispersion techniques enabled translation of this membrane-coated nanoparticle technology into clinical use. Zhang’s group also developed red blood cell–platelet hybrid membrane-coated PNPs (RBC-PNPs), which incorporate characteristics of both platelets and RBCs (Fig. 6) [¹⁵].

The reported technique laid the foundation for dual-membrane-coated nanoparticle preparation. Survival of CTCs in the circulation is essential for spread of tumors to distant organs. Additionally, platelets have been shown to protect tumor cells from natural killer cell attack by binding to CTCs [⁶]. Based on these principles, Gu’s group designed a platelet membrane-coated nanogel-based drug delivery system (TRAIL-Dox-PM-NV) capable of sequentially delivering an anticancer protein (tumor necrosis factor [TNF]-related apoptosis-inducing ligand) and a chemotherapeutic drug (Dox) to CTCs and primary tumor microenvironment (Fig. 7) [¹⁶].

Intravenous administration of TRAIL-Dox-PM-NV resulted in significant tumor shrinkage and decreased lung metastases in a breast cancer animal model. Gu’s group also constructed a platelet-mimicking nanocarrier (tPA-Ald-PM-NPs) to treat multiple myeloma (MM) (Fig. 8) [¹⁷].

The nanocarrier was composed of a polymeric core and a platelet membrane shell, loading with the proteasome inhibitor bortezomib to facilitate MM apoptosis. To overcome thrombus complication induced by MM, the nanovehicle surface was decorated with a clot-lysing drug (tPA). Alendronate was attached to the surface of nanovehicle to further endow the nanocarrier with bone-targeting ability. After intravenous injection, tPA-Ald-PM-NPs first targeted the bone microenvironment and subsequently targeted MMs by the naturally occurring platelet membrane ligand P-selectin. In vivo antiMM activity experiments revealed that tPA-Ald-PM-NPs can extensively prolong survival of MM-bearing Nod-SCID (nonobese diabetic-severe combined immunodeficiency disease) mice. Importantly, mice treated with this nanocarrier formulation exhibited fewer lung thrombus complications. Inspired by physiological signal amplification in vivo, Gu’s group also developed a two-sequential-module-based drug delivery system, comprising a signal transmission nanocarrier A (designated as NC_A) and an execution biomimetic nanocarrier B (designated as NC_B; Fig. 9) [¹⁸].

NC_A was composed of nanogel loaded with TNF-a, with the surface decorated with arginine-glycine-aspartic peptide motifs. NC_B consisted of a platelet membrane-coated acid-responsive dextran nanocarrier encapsulating the chemotherapeutic drug paclitaxel. NC_A was first injected into mice to induce the tumor vasculature branch to broadcast the targeting signal, and platelet membrane-coated NC_B was thereafter administered to efficiently target damaged tumor vessels and to maximize antitumor activity.

Homing ability of platelets to tumor cells in circulation presents an opportunity to attenuate tumor metastasis. King’s group designed and fabricated an activated platelet membrane-coated silica nanoparticle decorated with TRAIL. A lung metastasis animal model was used to investigate antimetastatic activity of the nanoplatform [¹⁹]. Their results showed that TRAIL-decorated platelet membrane-coated silica nanoparticles significantly decreased tumor nodule formulation in the lungs.

Tumor-associated platelet-targeted drug delivery

Platelets are well-known to play an indispensable role in tumor cell growth [²⁰], dissemination [²¹], angiogenesis [²²], and tumor-immune escape [²³]. Thus, targeting tumor-associated platelets with nanoparticle drug delivery systems may be a promising approach to treat cancer. Our group recently designed a biocompatible liposomal nanoparticle conjugated with a tumor-homing peptide (CREKA) on the surface and loaded with the reversible platelet inhibitor ticagrelor (referred to as CREKA-Lipo-T; Fig. 10) [²⁴].

We first demonstrated that platelets can induce transition of tumor cells into invasive phenotypes in vitro and subsequently showed that CREKA-Lipo-T can abolish this effect. These results showed that CREKA-Lipo-T can efficiently block tumor cell acquisition of an invasive phenotype. We then evaluated the interaction of platelets and tumor cells in vitro by confocal microscopy. CREKA-Lipo-T strongly inhibited tumor cell adhesion ability of platelets. Additionally, in contrast to the nontargeting nanoparticle Lipo-T, CREKA-Lipo-T efficiently accumulated in 4T1 solid tumors. CREKA-Lipo-T also showed remarkable antimetastatic activity in vivo, as evidenced by hematoxylin and eosin staining and immunostaining for proliferating cell nuclear antigen in lung tissues. Importantly, CREKA-Lipo-T did not cause notable bleeding complications, whereas free ticagrelor led to bleeding in the lungs.

In addition to promoting metastasis of tumor cells, some studies have indicated that platelets can also maintain the integrity of tumor blood vessels by secreting protective cytokines [²⁵,²⁶]. In a recent study, we described a method to specifically branch tumor vasculature and increase its permeability by locally depleting tumor-associated platelets. We constructed a polymer-lipid-peptide-based drug delivery system to codeliver a platelet-depleting antibody (R300) and a chemotherapeutic drug (Dox). A shell layer comprising matrix metalloproteinase 2 (MMP2)-cleavable peptides, lecithins, and PEGylated phospholipids were assembled into the polymer core to form an enzyme-responsive drug release (referred to as PLP-D-R). By using this strategy, local depletion of tumor-associated platelets and subsequent enhanced drug accumulation were achieved (Fig. 11) [²⁷].

Transmission electron microscopy (TEM) and dynamic light scattering (DLS) examination revealed a successfully constructed core–shell nanoparticle. We first tested the MMP2-dependent drug release profile and cytotoxicity in vitro. By using fluorescence imaging, photoacoustic imaging, and small animal positron emission tomography imaging, we demonstrated that tumor local platelet depletion can enhance nanoparticle accumulation. Additionally, we assessed the enhanced permeability and retention and Dox accumulation in tumors after intravenous injection of the nanoplatform. Drug concentration observed in the tumor group was thrice that in control groups. To explore the possible mechanism of enhanced drug perfusion, TEM imaging of tumor blood vessels was used. Compared with controls, widened breaches in blood vessel walls occurred with high frequency in the PLP-D-R-treated group (Fig. 12).

Lastly, we further validated anticancer efficacy of PLP-D-R in an MCF7 tumor-bearing nude mouse model. PLP-D-R exhibited higher suppression of tumor growth than either the PLP-D or free Dox group. Importantly, PLP-D-R did not cause any bleeding complications, whereas free R300 did.

Conclusions

Based on natural pathophysiological features of platelets, platelet membrane-based drug delivery systems have been shown to be promising strategies for treatment of several inflammation-eliciting diseases, including cancer, pathogen infection, and immune system diseases, with high biocompatibility. Despite advantages of platelets/platelet membranes as drug delivery systems, many obstacles are still observed for the translation of this approach into clinical applications. First, large-scale production technology is needed to produce sufficient supply of platelet membranes. Second, immunogenicity may pose a concern. The interaction between platelets and tumor tissue requires elucidation to design precision nanomedicine.

With regard to tumor-associated platelet targeting, the most important concern is avoidance of systematic bleeding complications. Targeted nanomedicine exhibits potential to overcome this issue by locally blocking the interaction between platelets and tumor cells. Further studies are required to elucidate molecular mechanisms that specifically mediate communication between platelets and tumor cells without affecting hemostatic functions. Can the suppression of platelets activity benefit to other therapeutic approaches, such as immunotherapy and chemotherapy? Evidence in literature suggest that platelets participate in immunosuppression and drug resistance [²³,²⁸]. Thus, antiplatelet therapy in cancer is possibly a highly powerful tool to be used in combination with other cancer treatment-related strategies.

References

[1] Gurtner GC, Werner S, Barrandon Y, Longaker MT. Wound repair and regeneration. Nature 2008; 453(7193): 314–321

[2] Furie B, Furie BC. Thrombus formation in vivo. J Clin Invest 2005; 115(12): 3355–3362

[3] Ho-Tin-Noé B, Goerge T, Cifuni SM, Duerschmied D, Wagner DD. Platelet granule secretion continuously prevents intratumor hemorrhage. Cancer Res 2008; 68(16): 6851–6858

[4] Gay LJ, Felding-Habermann B. Contribution of platelets to tumour metastasis. Nat Rev Cancer 2011; 11(2): 123–134

[5] Quail DF, Joyce JA. Microenvironmental regulation of tumor progression and metastasis. Nat Med 2013; 19(11): 1423–1437

[6] Mammadovabach E, Zigrino P, Brucker C, Bourdon C, Freund M, Arcangelis AD, Abrams SI, Orend G, Gachet C, Mangin PH. Platelet integrin a6b1 controls lung metastasis through direct binding to cancer cell–derived ADAM9. JCI Insight 2016; 1(14): e88245

[7] Yu LX, Yan L, Yang W, Wu FQ, Ling Y, Chen SZ, Tang L, Tan YX, Cao D, Wu MC, Yan HX, Wang HY. Platelets promote tumour metastasis via interaction between TLR4 and tumour cell-released high-mobility group box1 protein. Nat Commun 2014; 5: 5256

[8] Xu P, Zuo H, Chen B, Wang R, Ahmed A, Hu Y, Ouyang J. Doxorubicin-loaded platelets as a smart drug delivery system: an improved therapy for lymphoma. Sci Rep 2017; 7: 42632

[9] Nurden AT, Nurden P, Sanchez M, Andia I, Anitua E. Platelets and wound healing. Front Biosci 2008; 13: 3532–3548

[10] Nieswandt B, Hafner M, Echtenacher B, Männel DN. Lysis of tumor cells by natural killer cells in mice is impeded by platelets. Cancer Res 1999; 59(6): 1295–1300

[11] Wang C, Sun W, Ye Y, Hu Q, Bomba HN, Gu Z. In situ activation of platelets with checkpoint inhibitors for post-surgical cancer immunotherapy. Nat Biomed Eng 2017; 1: 0011

[12] Daly ME. Determinants of platelet count in humans. Haematologica 2011; 96(1): 10–13

[13] Li J, Sharkey CC, Wun B, Liesveld JL, King MR. Genetic engineering of platelets to neutralize circulating tumor cells. J Control Release 2016; 228: 38–47

[14] Hu CM, Fang RH, Wang KC, Luk BT, Thamphiwatana S, Dehaini D, Nguyen P, Angsantikul P, Wen CH, Kroll AV, Carpenter C, Ramesh M, Qu V, Patel SH, Zhu J, Shi W, Hofman FM, Chen TC, Gao W, Zhang K, Chien S, Zhang L. Nanoparticle biointerfacing by platelet membrane cloaking. Nature 2015; 526(7571): 118–121

[15] Dehaini D, Wei X, Fang RH, Masson S, Angsantikul P, Luk BT, Zhang Y, Ying M, Jiang Y, Kroll AV, Gao W, Zhang L. Erythrocyte-platelet hybrid membrane coating for enhanced nanoparticle functionalization. Adv Mater 2017 29(16):1606209

[16] Hu Q, Sun W, Qian C, Wang C, Bomba HN, Gu Z. Anticancer platelet-mimicking nanovehicles. Adv Mater 2015; 27(44): 7043–7050

[17] Hu Q, Qian C, Sun W, Wang J, Chen Z, Bomba HN, Xin H, Shen Q, Gu Z. Engineered nanoplatelets for enhanced treatment of multiple myeloma and thrombus. Adv Mater 2016; 28(43): 9573–9580

[18] Hu Q, Sun W, Qian C, Bomba HN, Xin H, Gu Z. Relay drug delivery for amplifying targeting signal and enhancing anticancer efficacy. Adv Mater 2017; 29(13): 1605803

[19] Li J, Ai Y, Wang L, Bu P, Sharkey CC, Wu Q, Wun B, Roy S, Shen X, King MR. Targeted drug delivery to circulating tumor cells via platelet membrane-functionalized particles. Biomaterials 2016; 76: 52–65

[20] Cho MS, Bottsford-Miller J, Vasquez HG, Stone R, Zand B, Kroll MH, Sood AK, Afshar-Kharghan V. Platelets increase the proliferation of ovarian cancer cells. Blood 2012; 120(24): 4869–4872

[21] Cooke NM, Spillane CD, Sheils O, O’Leary J, Kenny D. Aspirin and P2Y12 inhibition attenuate platelet-induced ovarian cancer cell invasion. BMC Cancer 2015; 15(1): 627

[22] Klement GL, Yip TT, Cassiola F, Kikuchi L, Cervi D, Podust V, Italiano JE, Wheatley E, Abou-Slaybi A, Bender E, Almog N, Kieran MW, Folkman J. Platelets actively sequester angiogenesis regulators. Blood 2009; 113(12): 2835–2842

[23] Rachidi S, Metelli A, Riesenberg B, Wu BX, Nelson MH, Wallace C, Paulos CM, Rubinstein MP, Garrett-Mayer E, Hennig M, Bearden DW, Yang Y, Liu B, Li Z. Platelets subvert T cell immunity against cancer via GARP-TGFb axis. Sci Immunol 2017; 2(11): 7911

[24] Zhang Y, Wei J, Liu S, Wang J, Han X, Qin H, Lang J, Cheng K, Li Y, Qi Y, Anderson GJ, Sukumar S, Li S, Nie G. Inhibition of platelet function using liposomal nanoparticles blocks tumor metastasis. Theranostics 2017; 7(5): 1062–1071

[25] Ho-Tin-Noé B, Goerge T, Wagner DD. Platelets: guardians of tumor vasculature. Cancer Res 2009; 69(14): 5623–5626

[26] Kisucka J, Butterfield CE, Duda DG, Eichenberger SC, Saffaripour S, Ware J, Ruggeri ZM, Jain RK, Folkman J, Wagner DD. Platelets and platelet adhesion support angiogenesis while preventing excessive hemorrhage. Proc Natl Acad Sci USA 2006; 103(4): 855–860

[27] Li S, Zhang Y, Wang J, Zhao Y, Ji T, Zhao X, Ding Y, Zhao X, Zhao R, Li F, Yang X, Liu S, Liu Z, Lai J, Whittaker AK, Anderson GJ, Wei J, Nie G. Nanoparticle-enabled local depletion of tumor-associated platelets disrupts tumor vascular barriers and augments tumor drug accumulation. Nat Biomed Eng 2017;1:667–679

[28] Ishikawa S, Miyashita T, Inokuchi M, Hayashi H, Oyama K, Tajima H, Takamura H, Ninomiya I, Ahmed AK, Harman JW, Fushida S, Ohta T. Platelets surrounding primary tumor cells are related to chemoresistance. Oncol Rep 2016; 36(2): 787–794

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