Available via license: CC BY 4.0
Content may be subject to copyright.
This article has been accepted for publication and undergone full peer review but has not been
through the copyediting, typesetting, pagination and proofreading process, which may lead to
differences between this version and the Version of Record. Please cite this article as doi:
10.1002/anbr.202000052
This article is protected by copyright. All rights reserved
Cell-based bio-hybrid delivery system for disease treatment
Chu-Xin Li, Yong-Dan Qi, Jun Feng* and Xian-Zheng Zhang*
C. X. Li, Y. D. Qi, Prof. J. Feng, Prof. X. Z. Zhang
Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry
Wuhan University
Wuhan 430072, P.R. China
* Emails: fengjun@whu.edu.cn (J. Feng), xz-zhang@whu.edu.cn (X. Z. Zhang)
C. X. Li and Y. D. Qi contributed equally to this work.
Keywords: synthetic material, live cell, drug delivery, immune cell, bio-hybrid
Accepted Article
. Li, Y. D. Qi, Prof. J. Feng, Prof. X. Z. Zhang
Accepted Article
. Li, Y. D. Qi, Prof. J. Feng, Prof. X. Z. Zhang
Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry
Accepted Article
Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry
Wuhan University
Accepted Article
Wuhan University
Wuhan 430072, P.R. China
Accepted Article
Wuhan 430072, P.R. China
* Emails: fengjun@whu.edu.cn (J. Feng), xz-zhang@whu.edu.cn (X. Z. Zhang)
Accepted Article
* Emails: fengjun@whu.edu.cn (J. Feng), xz-zhang@whu.edu.cn (X. Z. Zhang)
C. X. Li and Y. D. Qi contributed equally to this work.
Accepted Article
C. X. Li and Y. D. Qi contributed equally to this work.
ywords:
Accepted Article
ywords:
synthetic material,
Accepted Article
synthetic material,
This article is protected by copyright. All rights reserved
Abstract: Live cells are implicated in diverse biological processes, including nutrient transport
and removal of foreign substances. Their intelligent bio-functions with complex mechanisms
cannot be replicated at all in man-made materials despite the significant advance in material
design. Taking advantages of their biocompatibility and bio-tropic capability, various live cells
have been developed as a kind of special carriers for the on-demand delivery of therapeutic and
diagnostic agents in recent years. Furthermore, synthetic materials can be integrated with live
cells to provide bio-hybrid systems that inherit advantages from both the synthetic particles and
the natural cells. This review summarized recent strategies and advances in cell-based
bio-hybrid delivery systems for disease treatment. Challenges and opportunities in this field
were also discussed.
Accepted Article
design. Taking advantages of their biocompatibility and bio-tropic capability, various live cells
Accepted Article
design. Taking advantages of their biocompatibility and bio-tropic capability, various live cells
have been developed as a kind of special carriers for the on-demand delivery of therapeutic and
Accepted Article
have been developed as a kind of special carriers for the on-demand delivery of therapeutic and
diagnostic agents in recent years. Furthermore, synthetic materials can be integrated with live
Accepted Article
diagnostic agents in recent years. Furthermore, synthetic materials can be integrated with live
cells to provide bio-hybrid systems that inherit advantages from both the synthetic particles and
Accepted Article
cells to provide bio-hybrid systems that inherit advantages from both the synthetic particles and
the natural cells. This review summarized recent strategies and advances in cell-based
Accepted Article
the natural cells. This review summarized recent strategies and advances in cell-based
bio-hybrid delivery systems for disease treatment. Challenges and opportunities in this field
Accepted Article
bio-hybrid delivery systems for disease treatment. Challenges and opportunities in this field
were also discussed.
Accepted Article
were also discussed.
This article is protected by copyright. All rights reserved
1. Introduction
Synthetic delivery systems such as liposome and polymeric particles provide advantages in
improving the solubility, biocompatibility, and pharmacokinetics of free drugs. However,
considerable effort is still needed to improve their properties to satisfy clinical expectations.
Low delivery efficiency is still one of the major problems for therapeutics administration. It is
reported that only 0.7% of the injected nanoparticles can reach solid tumor in general.[1] For
tumor-tropic delivery, synthetic delivery systems, especially nanoscale materials, may rely on
passive targeting effects such as the enhanced permeability and retention (EPR) effect, which is
a special character of solid tumors due to the aggressive angiogenic environment.[2-3]
Nevertheless, the EPR effect for tumor-selective delivery is to some extent controversial and
researchers reported that active transport process via endothelial cells contributed to the
majority of nanoparticles‟ entrance into solid tumors.[4-6] In case of inflammatory diseases,
current therapeutic delivery take advantages of extravasation through leaky vasculature to cross
the endothelial barrier, or hitchhiking the inflammatory cells mediated sequestration activity.[7-9]
The transport processes of injected particles are usually heterogeneous and unpredictable,
which may lower the bioavailability of therapeutics. Besides, intravenously injected particles
will face multiple biological barriers, such as the well-known mononuclear phagocyte system,
during circulation and upon entering extracellular microenvironment.[10-13]
The innate functions of autologous cells have thus attracted great interest as new constituent
for developing powerful therapeutics. For example, red blood cells (RBCs) participate in
metabolic exchange and nutrients transport throughout the human body. Phagocytes like
monocytes and neutrophils circulate in peripheral blood, survey the inflammatory cues, and
migrate toward pathologic tissues to elicit pathogen eradication and tissues remodeling. The
question naturally arises that how to integrate drugs and therapeutic particles with cells. As
known, exotic intruders can be cleared by immune cells through multiple mechanisms. This
Accepted Article
Low delivery efficiency is still one of the major problems for therapeutics administration. It is
Accepted Article
Low delivery efficiency is still one of the major problems for therapeutics administration. It is
reported that only 0.7% of the injected nanoparticles can reach solid tumor in general.
Accepted Article
reported that only 0.7% of the injected nanoparticles can reach solid tumor in general.
tumor-tropic delivery, synthetic delivery systems, especially nanoscale materials, may rely on
Accepted Article
tumor-tropic delivery, synthetic delivery systems, especially nanoscale materials, may rely on
passive targeting effects such as the enhanced permeability and retention (EPR) effect, which is
Accepted Article
passive targeting effects such as the enhanced permeability and retention (EPR) effect, which is
a special character of solid tumors due to the aggressive angiogenic environment.
Accepted Article
a special character of solid tumors due to the aggressive angiogenic environment.
Nevertheless, the EPR effect for tumor-selective delivery is to some extent controversial and
Accepted Article
Nevertheless, the EPR effect for tumor-selective delivery is to some extent controversial and
researchers reported that active transport process via endothelial cells contributed to the
Accepted Article
researchers reported that active transport process via endothelial cells contributed to the
majority of nanoparticles‟ entrance into solid tumors.
Accepted Article
majority of nanoparticles‟ entrance into solid tumors.
current therapeutic delivery take advantages of extravasation through leaky vasculature to cross
Accepted Article
current therapeutic delivery take advantages of extravasation through leaky vasculature to cross
the endothelial barrier, or hitchhiking the inflammatory cells mediated sequestration activity.
Accepted Article
the endothelial barrier, or hitchhiking the inflammatory cells mediated sequestration activity.
The transport processes of injected particles are usually heterogeneous and unpredictable,
Accepted Article
The transport processes of injected particles are usually heterogeneous and unpredictable,
which may lower the bioavailability of therapeutics. Besides, intravenously injected particles
Accepted Article
which may lower the bioavailability of therapeutics. Besides, intravenously injected particles
will face multiple biological barriers, such as the well-known mononuclear phagocyte system,
Accepted Article
will face multiple biological barriers, such as the well-known mononuclear phagocyte system,
uring circulation and upon entering extracellular microenvironment.
Accepted Article
uring circulation and upon entering extracellular microenvironment.
The innate functions of autologous cells have thus attracted great interest as new constituent
Accepted Article
The innate functions of autologous cells have thus attracted great interest as new constituent
Accepted Article
for developing powerful therapeutics. For example, red blood cells (RBCs) participate in
Accepted Article
for developing powerful therapeutics. For example, red blood cells (RBCs) participate in
metabolic exchange and nutrients transport throughout the human body. Phagocytes like
Accepted Article
metabolic exchange and nutrients transport throughout the human body. Phagocytes like
This article is protected by copyright. All rights reserved
physiological barrier has been widely exploited as opportunity to develop bio-hybrid cell-based
delivery system, also called cellular vehicle or cellular carrier, where drugs and particles are
integrated with natural cells.[14-15] Taking advantages of the loading capacity, phagocytosis
activity and natural optimized transport patterns of live cells, therapeutic drugs and synthetic
materials loaded into cell carrier display improved pharmacokinetics and active targeting
capacity.
With the increasing understanding of cellular biology and the advance of nanotechnology,
intelligent functions of live cells as well as interactive design of therapeutic materials have also
been taken into consideration for developing novel bio-hybrid delivery systems. The plasticity,
diverse functional subtypes, and ingenious changes in response to different pathological stimuli
of intrinsic cells enable the feasibility of using synthetic materials to organically integrate with
cells and to regulate their diversity for multiple diagnostic and therapeutic purposes. By
harnessing advantages of synthetic materials as well as the special cellular activities of natural
cells, novel bio-hybrid delivery systems display multiple functionalities and biological
intelligence. As shown in Figure 1, we concisely summarize several interesting characters of
natural cells and attractive strategies that benefit from synthetic materials for constructing live
cell-based bio-hybrid delivery systems. We will provide a brief introduction of recent studies in
this field for disease treatment. Different types of intrinsic cells display distinct traffic patterns
in response to different pathology and disease process. Thus, we divide recent studies according
to cell types, including red blood cell, neutrophil, monocyte/macrophage, lymphocyte, and
platelet. The in vivo cell hitchhiking strategy is also introduced and compared with ex vivo cell
engineering. We also discuss about the advantages and limitations of different types of live
cell-based carrier, and provide our insights into future development of novel bio-hybrid
delivery systems.
Accepted Article
materials loaded into cell carrier display improved pharmacokinetics and active targeting
Accepted Article
materials loaded into cell carrier display improved pharmacokinetics and active targeting
capacity.
Accepted Article
capacity.
With the increasing understanding of cellular biology and the advance of nanotechnology,
Accepted Article
With the increasing understanding of cellular biology and the advance of nanotechnology,
intelligent functions of live cells as well as interactive design of therapeutic materials have also
Accepted Article
intelligent functions of live cells as well as interactive design of therapeutic materials have also
been taken into consideration for developing novel bio-hybrid delivery systems. The plasticity,
Accepted Article
been taken into consideration for developing novel bio-hybrid delivery systems. The plasticity,
diverse functional subtypes, and ingenious changes in response to different pathological stimuli
Accepted Article
diverse functional subtypes, and ingenious changes in response to different pathological stimuli
of intrinsic cells enable the feasibility of using synthetic materials to organically integrate with
Accepted Article
of intrinsic cells enable the feasibility of using synthetic materials to organically integrate with
cells and to regulate their diversity for multiple diagnostic and therapeutic purposes. By
Accepted Article
cells and to regulate their diversity for multiple diagnostic and therapeutic purposes. By
harnessing advantages of synthetic materials as well as the special cellular activities of natural
Accepted Article
harnessing advantages of synthetic materials as well as the special cellular activities of natural
cells, novel bio-hybrid delivery systems display multiple functionalities and biological
Accepted Article
cells, novel bio-hybrid delivery systems display multiple functionalities and biological
intelligence. As shown in
Accepted Article
intelligence. As shown in
natural cells and attractive strategies that benefit from synthetic materials for constructing live
Accepted Article
natural cells and attractive strategies that benefit from synthetic materials for constructing live
cell-based bio-hybrid delivery systems. We will provide a brief introduction of recent studies in
Accepted Article
cell-based bio-hybrid delivery systems. We will provide a brief introduction of recent studies in
this field for disease treatment. Different types of intrinsic cells display distinct traffic patterns
Accepted Article
this field for disease treatment. Different types of intrinsic cells display distinct traffic patterns
in response to different pathology and disease process. Thus, we divide recent studies according
Accepted Article
in response to different pathology and disease process. Thus, we divide recent studies according
Accepted Article
to cell types, including red blood cell, neutrophil, monocyte/macrophage, lymphocyte, and
Accepted Article
to cell types, including red blood cell, neutrophil, monocyte/macrophage, lymphocyte, and
platelet. The in vivo cell hitchhiking strategy is also introduced and compared with ex vivo cell
Accepted Article
platelet. The in vivo cell hitchhiking strategy is also introduced and compared with ex vivo cell
This article is protected by copyright. All rights reserved
2. Strategies for constructing bio-hybrid delivery systems
2.1. Red blood cell engineering
Red blood cell, also named erythrocyte, is the most abundant cell type and important cellular
component in blood. Learning from its transporter role for oxygen and carbon dioxide transfer,
researchers have made considerable efforts in manipulating red blood cells for in vivo drug and
particle delivery. Red blood cells display multiple advantages when serving as a carrier,
including prolonged circulation, benign biocompatibility, wide availability, and flexible
adaptability.[16] One of the major purposes of using red blood cell carriers is to improve
circulation half-life and to elongate in vivo retention period of laden cargoes.[17-19] Taking
advantage of the bio-distribution of red blood cells, several studies have reported
erythrocyte-hitchhiking strategy for lung targeting delivery.[20-21] Ukidve et al exploited another
biological traffic pattern of erythrocyte to deliver polystyrene nanoparticles loaded with
ovalbumin to the spleen, rather than lung, for immunization (Figure 2A).[22] It has been verified
that erythrocytes are able to capture pathogens during circulation and transport them to Kupffer
cells in the liver and professional antigen-presenting cells (APCs) to the spleen. By adjusting ex
vivo feeding ratio of nanoparticles and erythrocytes, the authors defined a preferable feeding
ratio of 300:1 (nanoparticles-to-erythrocytes), which displayed enhanced accumulation in
spleen and reduced accumulation in lung (Figure 2B).[22] Besides, this formulation also
promoted its internalization by APCs possibly due to the high density of conjugated
nanoparticles, which could increase the phosphatidylserine and physically mask CD47, a “don‟t
eat me” signal molecule, on the surface of erythrocytes. This OVA-loaded
nanoparticles-conjugated erythrocytes displayed therapeutic potential as a vaccine for tumor
that expressed OVA antigens.
Researchers also cleverly manipulated the surface receptor proteins on red blood cells to
construct smart delivery system. Gu‟s group linked glucose derivative-modified insulin with
Accepted Article
researchers have made considerable efforts in manipulating red blood cells for in vivo drug and
Accepted Article
researchers have made considerable efforts in manipulating red blood cells for in vivo drug and
particle delivery. Red blood cells display multiple advantages when serving as a carrier,
Accepted Article
particle delivery. Red blood cells display multiple advantages when serving as a carrier,
including prolonged circulation, benign biocompatibility, wide availability,
Accepted Article
including prolonged circulation, benign biocompatibility, wide availability,
adaptability.
Accepted Article
adaptability.
[16]
Accepted Article
[16]
One of the major purposes of using red blood cell carriers is to improve
Accepted Article
One of the major purposes of using red blood cell carriers is to improve
circulation half-life and to elongate in vivo retention period of laden cargoes.
Accepted Article
circulation half-life and to elongate in vivo retention period of laden cargoes.
advantage of the bio-distribution of red blood cells, several studies have reported
Accepted Article
advantage of the bio-distribution of red blood cells, several studies have reported
erythrocyte-hitchhiking strategy for lung targeting delivery.
Accepted Article
erythrocyte-hitchhiking strategy for lung targeting delivery.
biological traffic pattern of erythrocyte to deliver polystyrene nanoparticles loaded with
Accepted Article
biological traffic pattern of erythrocyte to deliver polystyrene nanoparticles loaded with
ovalbumin to the spleen, rather than lung, for immunization (
Accepted Article
ovalbumin to the spleen, rather than lung, for immunization (
that erythrocytes are able to capture pathogens during circulation and transport them to Kupffer
Accepted Article
that erythrocytes are able to capture pathogens during circulation and transport them to Kupffer
cells in the liver and professional antigen-presenting cells (APCs) to the spleen. By adjusting ex
Accepted Article
cells in the liver and professional antigen-presenting cells (APCs) to the spleen. By adjusting ex
feeding ratio of nanoparticles and erythrocytes, the authors defined a preferable feeding
Accepted Article
feeding ratio of nanoparticles and erythrocytes, the authors defined a preferable feeding
tio of 300:1 (nanoparticles-
Accepted Article
tio of 300:1 (nanoparticles-
Accepted Article
spleen and reduced accumulation in lung (Figure 2B).
Accepted Article
spleen and reduced accumulation in lung (Figure 2B).
promoted its internalization by APCs possibly due to the high density of conjugated
Accepted Article
promoted its internalization by APCs possibly due to the high density of conjugated
ticles, which could increase the phosphatidylserine and physically mask CD47, a “don‟t
Accepted Article
ticles, which could increase the phosphatidylserine and physically mask CD47, a “don‟t
eat me” signal molecule, on the surface of erythrocytes. This OVA-loaded
Accepted Article
eat me” signal molecule, on the surface of erythrocytes. This OVA-loaded
This article is protected by copyright. All rights reserved
abundant glucose transporter molecule on red blood cells.[23] This interaction is reversible,
making it possible to release insulin under high glucose conditions due to the competitive
interaction of free glucose with glucose transporter molecule (Figure 2C).[23] Hotz et al
demonstrated the potentials of red blood cells in binding and clearing cell-free RNA for
preventing lung injury, which are benefited from surface receptors.[24] Efforts in excavating the
protein components of red blood cells may help advance current erythrocyte-based therapeutics
and promote their clinical translation.
There are some studies that also adopted the biomaterial-assisted/engineered red blood cells
strategy while aimed at other purposes. Zhao and coworkers have reported a strategy of
shielding surface antigens of red blood cells by chemical frameworks for blood transfusion
(Figure 2D).[25] They anchored horseradish peroxidase (HRP) on cellular surface by using
biocompatible anchor molecule (BAM) that contained an oleyl chain for membrane insertion.
In the presence of substrates including polysialic acid (PSA), tyramine and hydrogen peroxide,
HRP catalyzed the formation of a 3D framework encompassing the red blood cell. This method
did not affect the fluidity and meanwhile shield the immunogenic antigens on red blood cells,
providing a universal strategy for modifying red blood cells and adoptive transfer. Zhu and
coworkers developed a strategy of using zirconium-based metal-organic framework (MOF)
nanoparticles for cryopreservation of red blood cells, without the need of any toxic agents and
solvents.[26] Herein, the authors adjusted different parameters of MOF nanoparticles to optimize
the cryopreservation effect. They found that MOF nanoparticles improved the cryopreservation
by inhibiting ice recrystallization meanwhile catalyzing the melting of ice crystals, which may
destroy the structure of red blood cells. Some researchers also excavated the potential of red
blood cells as a versatile scaffold for generating microreactors and immune modulatory
agents.[27-32]
We can summarize from these studies that current red blood cells engineering mainly
Accepted Article
preventing lung injury, which are benefited from surface receptors.
Accepted Article
preventing lung injury, which are benefited from surface receptors.
protein components of red blood cells may help advance current erythrocyte-based therapeutics
Accepted Article
protein components of red blood cells may help advance current erythrocyte-based therapeutics
and promote their clinical translation.
Accepted Article
and promote their clinical translation.
There are some studies that also adopted the biomaterial-assisted/engineered red blood cells
Accepted Article
There are some studies that also adopted the biomaterial-assisted/engineered red blood cells
strategy while aimed at other purposes. Zhao and coworkers have reported a strategy of
Accepted Article
strategy while aimed at other purposes. Zhao and coworkers have reported a strategy of
shielding surface antigens of red blood cells by chemical frameworks for blood transfusion
Accepted Article
shielding surface antigens of red blood cells by chemical frameworks for blood transfusion
(Figure 2D).
Accepted Article
(Figure 2D).
[25]
Accepted Article
[25]
They anchored horseradish peroxida
Accepted Article
They anchored horseradish peroxida
biocompatible anchor molecule (BAM) that contained an oleyl chain for membrane insertion.
Accepted Article
biocompatible anchor molecule (BAM) that contained an oleyl chain for membrane insertion.
In the presence of substrates including polysialic acid (PSA), tyramine and hydrogen peroxide,
Accepted Article
In the presence of substrates including polysialic acid (PSA), tyramine and hydrogen peroxide,
P catalyzed the formation of a 3D framework encompassing the red blood cell. This method
Accepted Article
P catalyzed the formation of a 3D framework encompassing the red blood cell. This method
did not affect the fluidity and meanwhile shield the immunogenic antigens on red blood cells,
Accepted Article
did not affect the fluidity and meanwhile shield the immunogenic antigens on red blood cells,
providing a universal strategy for modifying red blood cells and adoptive transfer. Zhu and
Accepted Article
providing a universal strategy for modifying red blood cells and adoptive transfer. Zhu and
coworkers developed a strategy of using zirconium-based metal-organic framework (MOF)
Accepted Article
coworkers developed a strategy of using zirconium-based metal-organic framework (MOF)
Accepted Article
nanoparticles for cryopreservation of red blood cells, without the need of any toxic agents and
Accepted Article
nanoparticles for cryopreservation of red blood cells, without the need of any toxic agents and
[26]
Accepted Article
[26]
Herein, the authors adjusted different parameters of MOF nanoparticles to optimize
Accepted Article
Herein, the authors adjusted different parameters of MOF nanoparticles to optimize
the cryopreservation effect. They found that MOF nanoparticles improved the cryopreservation
Accepted Article
the cryopreservation effect. They found that MOF nanoparticles improved the cryopreservation
Accepted Article
by inhibiting ice recrystallization meanwhile catalyzing the melting of ice crystals, which may
Accepted Article
by inhibiting ice recrystallization meanwhile catalyzing the melting of ice crystals, which may
This article is protected by copyright. All rights reserved
involves three directions: 1) generating delivery system with biocompatibility and prolonged
circulations, 2) excavating smart responsiveness and therapeutic potentials of erythrocytes‟
components, 3) serving as a special scaffold with unique shape and characteristics for artificial
modification.
2.2. Neutrophil carriers
Neutrophil is the major effector immune cell in response to acute inflammation, which is
usually occurred in infectious site and sterile injured tissues such as burn and hypoxia.[33]
Neutrophils also participate in chronic inflammation, adaptive immune responses and tumor
development. The recruitment and infiltration cascade of neutrophils is initiated by the
endothelium following the gradient of inflammatory factors like cytokine and chemokine.
Therefore, neutrophil is usually taken as an indicator of inflammation and relevant
diseases,[34-37] and has been widely studied as a drug delivery system in recent years.[38] For
example, neutrophil-based delivery system can cross the blood-brain barrier (BBB) and
overcome the blood–brain-tumor barrier (BBTB) for malignant glioma treatment.[39-41] Hou
and coworkers integrated neutrophils and monocytes with cyclo-(Arg-Gly-Asp-D-Tyr-Lys)
(cRGD) peptide-modified drug-loaded liposomes, realizing successful comigration across BBB
for delivering therapeutic molecules for cerebral ischemia.[39] Wu et al incubated neutrophils
with drug-loaded magnetic mesoporous silica nanoparticles for magnetic resonance (MR)
imaging tracking of their in vivo traffic toward inflamed glioma tissues (Figure 3A).[40]
Zhang‟s group reported a neutrophil-based chemotherapy delivery system that targeted
inflammatory signals in the brain after surgical resection of glioma.[41] Besides, they also
utilized similar neutrophil-based carrier to deliver chemotherapeutics toward inflamed tumor
tissues after radiotherapy.[42]
An additional advantage of the neutrophil-based delivery system is that in response to
inflammatory stimuli, neutrophils will form neutrophil extracellular traps (NETs) and release
Accepted Article
2.2. Neutrophil carriers
Accepted Article
2.2. Neutrophil carriers
Neutrophil is the major effector immune cell in response to acute inflammation, which is
Accepted Article
Neutrophil is the major effector immune cell in response to acute inflammation, which is
usually occurred in infectious site and sterile injured tissues such as burn and hypoxia.
Accepted Article
usually occurred in infectious site and sterile injured tissues such as burn and hypoxia.
Neutrophils also participate in chronic inflammation, adaptive immune responses and tumor
Accepted Article
Neutrophils also participate in chronic inflammation, adaptive immune responses and tumor
opment. The recruitment and infiltration cascade of neutrophils is initiated by the
Accepted Article
opment. The recruitment and infiltration cascade of neutrophils is initiated by the
helium following the gradient of inflammatory factors like cytokine and chemokine.
Accepted Article
helium following the gradient of inflammatory factors like cytokine and chemokine.
Therefore, neutrophil is usually taken as an indicator of inflammation and relevant
Accepted Article
Therefore, neutrophil is usually taken as an indicator of inflammation and relevant
[34-37]
Accepted Article
[34-37]
and has been widely studied as a drug delivery system in recent years.
Accepted Article
and has been widely studied as a drug delivery system in recent years.
example, neutrophil-based delivery system
Accepted Article
example, neutrophil-based delivery system
overcome the blood–brain
Accepted Article
overcome the blood–brain
and coworkers integrated neutrophils and monocytes with cyclo-(Arg-Gly-Asp-D-Tyr-Lys)
Accepted Article
and coworkers integrated neutrophils and monocytes with cyclo-(Arg-Gly-Asp-D-Tyr-Lys)
RGD) peptide-modified drug-loaded liposomes, realizing successful comigration across BBB
Accepted Article
RGD) peptide-modified drug-loaded liposomes, realizing successful comigration across BBB
for delivering therapeutic molecules for cerebral ischemia.
Accepted Article
for delivering therapeutic molecules for cerebral ischemia.
with drug-loaded magnetic mesoporous silica nanoparticles for magnetic resonance (MR)
Accepted Article
with drug-loaded magnetic mesoporous silica nanoparticles for magnetic resonance (MR)
Accepted Article
imaging tracking of their in vivo traffic toward inflamed glioma tissues
Accepted Article
imaging tracking of their in vivo traffic toward inflamed glioma tissues
Zhang‟s group reported a neutrophil-based chemotherapy delivery system that targeted
Accepted Article
Zhang‟s group reported a neutrophil-based chemotherapy delivery system that targeted
Accepted Article
inflammatory signals in the brain after surgical resection of glioma.
Accepted Article
inflammatory signals in the brain after surgical resection of glioma.
This article is protected by copyright. All rights reserved
the loaded drug to extracellular environment, which overcomes a delivery problem of cellular
vehicles that the loaded drug is usually trapped in the carrier cell and cannot reach the preferred
targets.
Zhang et al integrated neutrophils with photocatalytic nanoparticles Fe3O4@TiO2 (Figure
3B), containing an iron oxide core and a titanium dioxide shell, to target infection nidus and
activate innate immune system for eradicating pathogens.[43] Natural neutrophils displayed
certain antibiotic effect in vitro, which was further boosted after Fe3O4@TiO2 integration
(Figure 3C). Upon enriching at infectious tissues, photocatalytic nanoparticles produced
abundant reactive oxygen species (ROS) under near-ultraviolet irradiation, which could not
only eradicate surrounding microorganisms but also induced the apoptosis of the transporter
neutrophils. The apoptotic neutrophils produced and released a series chemokine such as
MCP-1 and MIP-1β, recruiting macrophages and amplifying subsequent innate immune
responses of the host for further elimination of pathogens. The therapeutic potentials of this
platform were verified in mouse model with necrotizing fasciitis and intraabdominal infection.
2.3. Monocyte/macrophage carriers
Monocyte and macrophages are important components of innate immune system,
participating in homeostasis and inflammation development. Monocytes, the bloodborne
precursor of both macrophage and dendritic cell (DC) lineages, can migrate following the
stimulus gradients, emigrate from blood vessels, infiltrate into tissues and differentiate into
macrophages to elicit various functions to control infection and disease progress.[44-45] While
macrophages, which distribute throughout the body and all organs, mainly reside in tissues and
monitors the surrounding physiological changes. Both monocyte and macrophage lineages
display heterogeneity and can divide into various subsets in response to specific
microenvironment, making them hot candidates for site-specific targeting delivery. For
example, it has been verified that macrophages can be recruited deep into hypoxic area of
Accepted Article
, containing an iron oxide core and a titanium dioxide shell, to target infection nidus and
Accepted Article
, containing an iron oxide core and a titanium dioxide shell, to target infection nidus and
activate innate immune system for eradicating pathogens.
Accepted Article
activate innate immune system for eradicating pathogens.
certain antibiotic effect in vitro, which was further boosted after
Accepted Article
certain antibiotic effect in vitro, which was further boosted after
(Figure 3C). Upon enriching at infectious tissues, photocatalytic nanoparticles produced
Accepted Article
(Figure 3C). Upon enriching at infectious tissues, photocatalytic nanoparticles produced
reactive oxygen species (ROS) under near-ultraviolet irradiation, which could not
Accepted Article
reactive oxygen species (ROS) under near-ultraviolet irradiation, which could not
only eradicate surrounding microorganisms but also induced the apoptosis of the transporter
Accepted Article
only eradicate surrounding microorganisms but also induced the apoptosis of the transporter
neutrophils. The apoptotic neutrophils produced and released a series chemokine such as
Accepted Article
neutrophils. The apoptotic neutrophils produced and released a series chemokine such as
MCP-1 and MIP-1β, recruiting macrophages and amplifying subsequent innate immune
Accepted Article
MCP-1 and MIP-1β, recruiting macrophages and amplifying subsequent innate immune
responses of the host for further elimination of pathogens. The therapeutic potentials of this
Accepted Article
responses of the host for further elimination of pathogens. The therapeutic potentials of this
platform were verified in mouse model with necrotizing fasciitis and intraabdominal infection.
Accepted Article
platform were verified in mouse model with necrotizing fasciitis and intraabdominal infection.
2.3. Monocyte/macrophage carriers
Accepted Article
2.3. Monocyte/macrophage carriers
Monocyte and macrophages are important components of innate immune system,
Accepted Article
Monocyte and macrophages are important components of innate immune system,
participating in homeostasis and inflammation development. Monocytes, the bloodborne
Accepted Article
participating in homeostasis and inflammation development. Monocytes, the bloodborne
precursor of both macrophage and dendritic cell (DC) lineages,
Accepted Article
precursor of both macrophage and dendritic cell (DC) lineages,
stimulus gradients, emigrate from blood vessels, infiltrate into tissues and differentiate into
Accepted Article
stimulus gradients, emigrate from blood vessels, infiltrate into tissues and differentiate into
Accepted Article
macrophages
Accepted Article
macrophages
to
Accepted Article
to
elicit various functions to control infection and disease progress.
Accepted Article
elicit various functions to control infection and disease progress.
macrophages, which distribute throughout the body and all organs, mainly reside in tissues and
Accepted Article
macrophages, which distribute throughout the body and all organs, mainly reside in tissues and
This article is protected by copyright. All rights reserved
tumor.[46] Hence, the specific while multifarious distribution patterns and homing capacities of
monocytes and macrophages are widely exploited for diagnosis and therapy for tumors and
inflammatory diseases.[47-49] Our group previously reported a contact-cell-enhanced
photodynamic therapy by anchoring functional molecule containing protoporphyrin X (PpIX)
on the plasma membrane of macrophages for tumor treatment (Figure 3D).[50] The engineered
macrophages actively accumulated at tumor tissues, recognized, and interacted with cancer
cells. This interaction formed macrophage-to-cancer cell contact, which concentrated PpIX and
ROS production around cancer cells, and improved the therapeutic outcomes than free PpIX.
This membrane insertion strategy for loading cargoes onto surface of macrophage-based
delivery system cleverly exploited the cell-cell contact for concentrating cytotoxic agents onto
cancer cells, taking advantages of natural cancer cell recognition capacity of macrophages
meanwhile circumventing the problem of drug release from cell-based carriers.
Zhang et al reported a macrophage-based chemotherapy delivery system with high drug
dosage.[51] They engineered a silica based nanoparticle (DSN) for loading doxorubicin (DOX)
and coordinated DSN with the macrophage carrier, with a high loading efficacy up to 16.6 μg
per cell (Figure 3E).[51] DSN possessed a robust silica sheath that degraded quite slowly in the
first few hours during circulation, preventing drug release in lysosomes of macrophages before
reaching targets. Upon reaching tumor tissues, the silica core was more susceptible to
degradation and released DOX for tumor inhibition. The authors took notice of the intracellular
lysosomal activity, which is also a troublesome limitation for cell based delivery system, and
prudentially designed nanoparticle carrier to guarantee efficient drug preservation during
transport meanwhile realized rapid drug release upon reaching tumor tissues.
Li‟s group loaded inflammatory monocytes with legumain-responsive nanoparticles for
treating lung metastatic breast tumors.[52-53] Cytotoxic agent mertansine was linked to
poly(styrene-co-maleic anhydride) (SMA) via legumain-sensitive peptide to obtain
Accepted Article
on the plasma membrane of macrophages for tumor treatment
Accepted Article
on the plasma membrane of macrophages for tumor treatment
macrophages actively accumulated at tumor tissues, recognized, and interacted with cancer
Accepted Article
macrophages actively accumulated at tumor tissues, recognized, and interacted with cancer
ls. This interaction formed macrophage-
Accepted Article
ls. This interaction formed macrophage-
ROS production around cancer cells, and improved the therapeutic outcomes than free PpIX.
Accepted Article
ROS production around cancer cells, and improved the therapeutic outcomes than free PpIX.
membrane insertion
Accepted Article
membrane insertion
delivery system cleverly exploited the cell-cell contact for concentrating cytotoxic agents onto
Accepted Article
delivery system cleverly exploited the cell-cell contact for concentrating cytotoxic agents onto
er cells, taking advantages of natural cancer cell recognition capacity of macrophages
Accepted Article
er cells, taking advantages of natural cancer cell recognition capacity of macrophages
meanwhile circumventing the problem of drug release from cell-based carriers.
Accepted Article
meanwhile circumventing the problem of drug release from cell-based carriers.
et al reported a macrophage-based chemotherapy delivery system with high drug
Accepted Article
et al reported a macrophage-based chemotherapy delivery system with high drug
[51]
Accepted Article
[51]
They engineered a silica based nanoparticle (DSN) for loading doxorubicin (D
Accepted Article
They engineered a silica based nanoparticle (DSN) for loading doxorubicin (D
and coordinated DSN with the macrophage carrier, with a high loading efficacy up to 16.6 μg
Accepted Article
and coordinated DSN with the macrophage carrier, with a high loading efficacy up to 16.6 μg
per cell (Figure 3E).
Accepted Article
per cell (Figure 3E).
[51]
Accepted Article
[51]
first few hours during circulation, preventing drug release in lysosomes of macrophages before
Accepted Article
first few hours during circulation, preventing drug release in lysosomes of macrophages before
Accepted Article
reaching targets. Upon reaching tumor tissues, the silica core was more susceptible to
Accepted Article
reaching targets. Upon reaching tumor tissues, the silica core was more susceptible to
degradation and released D
Accepted Article
degradation and released D
lysosomal activity, which is also a troublesome limitation for cell based delivery system, and
Accepted Article
lysosomal activity, which is also a troublesome limitation for cell based delivery system, and
prudentially designed nanoparticle carrier to guarantee efficient drug preservation during
Accepted Article
prudentially designed nanoparticle carrier to guarantee efficient drug preservation during
This article is protected by copyright. All rights reserved
SMA-AANK-Mertansine conjugate. This conjugate self-assembled into nanoparticles (SMNs)
and were loaded into inflammatory monocytes to prepare monocyte-based delivery system
(M-SMNs) for targeting cancer cells with lung metastasis (Figure 3F).[52] Upon settle down in
metastatic niche, monocytes activated and switched into macrophages, which expressed a high
level of legumain, which triggered the release of mertansine. The authors found that the
anticancer drug of mertansine was released in the form of free drug as well as microvesicles that
were derived from monocyte carriers. This cell-based delivery system exploited not only the
homing capacity but also biological changes of monocytes as an off-on switch to realize
tumor-specific drug transport and release.
Researchers also took advantage of cues in disease-associated microenvironment to realize
stimuli-responsive drug release. Chang et al loaded polymeric nanoparticles with astaxanthin
(AST) and trametinib (TRA) and modified this nanomedicine with matrix metalloproteinase-2
(MMP-2) cleavable peptide, which was overexpressed in idiopathic pulmonary fibrosis (IPF)
nidus, for pathology-responsive drug release.[54] They collected peripheral monocytes from
mice of IPF to isolate and obtain multipotent cells, which possessed homing capacity toward
damaged lung areas and participated in lung normalization. Then, they adhered the as-designed
nanomedicine onto cellular surface through interaction with CXCR4 on the multipotent cells.
Upon active homing toward injured lung tissues, both the laden drugs and the carrier
multipotent cells would elicit therapeutic effects and synergized with each other to reverse IPF.
The strategy of combining cell-based delivery system with enzyme-mediated catalytic
reactions to trigger drug release provides intelligent responsiveness toward different stimuli,
including pathological changes in microenvironment and natural immune cells recognition and
activation. However, considering that current studies mostly utilized enzymatic reaction to
realize drug release from synthetic particles rather than live cell carriers, there are some
dilemma need to be noticed and settled. Intracellular enzymatic catalysis dose not directly solve
Accepted Article
level of legumain, which triggered the release of mertansine. The authors found that the
Accepted Article
level of legumain, which triggered the release of mertansine. The authors found that the
icancer drug of mertansine was released in the form of free drug as well as microvesicles that
Accepted Article
icancer drug of mertansine was released in the form of free drug as well as microvesicles that
were derived from monocyte carriers. This cell-based delivery system exploited not only the
Accepted Article
were derived from monocyte carriers. This cell-based delivery system exploited not only the
homing capacity but also biological changes of monocytes as an off-on switch to realize
Accepted Article
homing capacity but also biological changes of monocytes as an off-on switch to realize
or-specific drug transport and release.
Accepted Article
or-specific drug transport and release.
Researchers also took advantage of cues in disease-associated microenvironment to realize
Accepted Article
Researchers also took advantage of cues in disease-associated microenvironment to realize
stimuli-responsive drug release.
Accepted Article
stimuli-responsive drug release.
(AST) and trametinib (TRA) and modified this nanomedicine with matrix metalloproteinase-
Accepted Article
(AST) and trametinib (TRA) and modified this nanomedicine with matrix metalloproteinase-
(MMP-2) cleavable peptide, which was overexpressed in idiopathic pulmonary fibrosis (IPF)
Accepted Article
(MMP-2) cleavable peptide, which was overexpressed in idiopathic pulmonary fibrosis (IPF)
nidus, for pathology-responsive drug release.
Accepted Article
nidus, for pathology-responsive drug release.
mice of IPF
Accepted Article
mice of IPF
to
Accepted Article
to
isolate and obtain multipotent cells, which possess
Accepted Article
isolate and obtain multipotent cells, which possess
damaged lung areas and participated in lung normalization
Accepted Article
damaged lung areas and participated in lung normalization
nanomedicine onto cellular surface through interaction with CXCR4 on the multipotent cells.
Accepted Article
nanomedicine onto cellular surface through interaction with CXCR4 on the multipotent cells.
Accepted Article
Upon active homing toward injured lung tissues, both the laden drugs and the carrier
Accepted Article
Upon active homing toward injured lung tissues, both the laden drugs and the carrier
multipotent cells would elicit therapeutic effects and synergized with each other to revers
Accepted Article
multipotent cells would elicit therapeutic effects and synergized with each other to revers
The strategy of combining cell-based delivery system with enzyme-mediated catalytic
Accepted Article
The strategy of combining cell-based delivery system with enzyme-mediated catalytic
reactions to trigger drug release provides intelligent responsiveness toward different stimuli
Accepted Article
reactions to trigger drug release provides intelligent responsiveness toward different stimuli
This article is protected by copyright. All rights reserved
the problem of transporting drugs from intracellular compartment of live cell carriers to
extracellular environment for acting on target cells. This problem may require the extracellular
secretion activity or artificial destroy of live cells carriers. Meanwhile, extracellular enzymatic
activity-mediated drug release requires the conjugation and retention of laden drugs and
cargoes on the surface of live cell carriers. This is to some extent difficult and require technical
live cell modification, since live cells possess phagocytic activities, especially for monocytes
and macrophages, which are important components of the mononuclear-phagocyte system.
Xu and coworkers have utilized ultrasound-mediated rupture to realize drug release from
macrophage carrier (Figure 3G).[55] Chemotherapy DOX and perfluoropentane (PFP) were
loaded into hollow mesoporous organosilica nanoparticles (HMONs), which were further
internalized into macrophages for active homing to tumor tissues. PFP functioned as an
ultrasonography imaging-agent for tracking macrophage migration, and evaporated to disrupt
macrophage vehicle upon ultrasound sonication for releasing chemotherapy drugs. This
method provided both real-time ultrasound imaging capability as well as on-demand
controllability with spatial precision.
By harnessing the phenomenon that macrophages can phagocytize and excrete
oligonucleotides into the surrounding environments, Wayne and coworkers utilized
macrophages to delivery small interfering RNA (siRNA) for inhibiting breast tumor growth.[56]
They utilized several co-incubation models to demonstrate the feasibility of siRNA horizontal
transfer from macrophages to cancer cells. They further studied the siRNA transfer dynamics,
and explored the associations between the transfection efficacy in cancer cells and the
phenotypes of macrophages. They found that the alternatively activated macrophages (also
called M2 macrophages) were better gene carrier for transferring siRNA to cancer cells, due to
their special activities in siRNA uptake and enhanced exosomal secretion for siRNA release.
This study linked the siRNA transfer efficacy to phenotypes of macrophages and provided a
Accepted Article
cargoes on the surface of live cell carriers. This is to some extent difficult and require technical
Accepted Article
cargoes on the surface of live cell carriers. This is to some extent difficult and require technical
ve cell modification, since live cells possess phagocytic activities, especially for monocytes
Accepted Article
ve cell modification, since live cells possess phagocytic activities, especially for monocytes
and macrophages, which
Accepted Article
and macrophages, which
and coworkers have utilized ultrasound-mediated rupture to realize drug release from
Accepted Article
and coworkers have utilized ultrasound-mediated rupture to realize drug release from
macrophage carrier (Figure 3G).
Accepted Article
macrophage carrier (Figure 3G).
loaded into hollow mesoporous organosilica nanoparticles (HMONs), which were further
Accepted Article
loaded into hollow mesoporous organosilica nanoparticles (HMONs), which were further
internalized into macrophages for active homing to tumor tissues
Accepted Article
internalized into macrophages for active homing to tumor tissues
ultrasonography imaging-agent for tracking macrophage migration, and evaporated to disrupt
Accepted Article
ultrasonography imaging-agent for tracking macrophage migration, and evaporated to disrupt
acrophage vehicle upon ultrasound sonication for releasing chemotherapy drugs. This
Accepted Article
acrophage vehicle upon ultrasound sonication for releasing chemotherapy drugs. This
method provided both real-time ultrasound imaging capability as well as on-demand
Accepted Article
method provided both real-time ultrasound imaging capability as well as on-demand
controllability with spatial precision.
Accepted Article
controllability with spatial precision.
By harnessing the phenomenon that macrophages can phagocytize and excrete
Accepted Article
By harnessing the phenomenon that macrophages can phagocytize and excrete
oligonucleotides into the surrounding environments, Wayne and coworkers utilized
Accepted Article
oligonucleotides into the surrounding environments, Wayne and coworkers utilized
macrophages to delivery small interfering RNA (siRNA) for inhibiting breast tumor growth.
Accepted Article
macrophages to delivery small interfering RNA (siRNA) for inhibiting breast tumor growth.
They utilized several co-incubation models to demonstrate the feasibility of siRNA horizontal
Accepted Article
They utilized several co-incubation models to demonstrate the feasibility of siRNA horizontal
Accepted Article
transfer from macrophages to cancer cells. They further studied the siRNA transfer dynamics,
Accepted Article
transfer from macrophages to cancer cells. They further studied the siRNA transfer dynamics,
and explored the associations between the transfection efficacy in cancer cells and the
Accepted Article
and explored the associations between the transfection efficacy in cancer cells and the
This article is protected by copyright. All rights reserved
special insight in the field of excavating underlying functionalities of macrophage carriers. Guo
et al directly loaded DOX with macrophages via electrostatic and hydrophobic interactions for
treating metastatic ovarian carcinoma.[57] They discovered that the classically activated
macrophages, also known as pro-inflammatory M1 macrophages, can formed tunneling
nanotube network between themselves and cancer cells. This specific nanotube functioned as a
drug transportation expressways, facilitating ultrafast transfer of the laden drug DOX from cell
carrier toward cancer cells. Besides, relying on the intrinsic recognition of cancer cells by
macrophages, this delivery system display preferable intelligent cancer cell-specific drug
delivery capacity. We can notice from these studies that heterogeneity of macrophages can
provide new delivery methods and strategies. Whether M2 macrophage, M1 macrophage, or
macrophage of other subsets can provide the most satisfactory delivery outcome is uncertain. It
seems that they are competent in delivering different types of cargoes, because their
functionalities and biological behaviors display diversity and huge otherness, which also
stimulate great interests and efforts in this field. Current studies in this field are far more enough,
and the underlying mechanisms and potentials remain unclear. Exploiting the heterogeneity of
monocyte and macrophage can be challenging meanwhile promising for developing advanced
delivery system.
Since monocytes and macrophages are professional phagocytes, unlike neutrophils that can
form NETs for unloading cargoes, it is necessary to solve the problem of drug release when
using monocyte/macrophage carriers. We summarized from recent studies that there are about
four strategies to circumvent this dilemma: 1) restrict the laden cargoes on the cellular surface
outside live cells and exploit environmental cues to trigger drug release, 2) take advantage of
cell-cell contact to realize cytotoxic agent transfer, 3) excavate the cell-derived microvesicles
and exosomes to transmit drugs, 4) utilize external stimuli such as ultrasound to disrupt cellular
carriers. These strategies are also adaptable for other types of cell carrier.
Accepted Article
nanotube network between themselves and cancer cells. This specific nanotube functioned as a
Accepted Article
nanotube network between themselves and cancer cells. This specific nanotube functioned as a
drug transportation expressways, facilitating ultrafast transfer of the laden drug
Accepted Article
drug transportation expressways, facilitating ultrafast transfer of the laden drug
carrier toward cancer cells. Besides, relying on the intrinsic recognition of cancer cells by
Accepted Article
carrier toward cancer cells. Besides, relying on the intrinsic recognition of cancer cells by
macrophages, this delivery system display preferable intelligent cancer cell-specific drug
Accepted Article
macrophages, this delivery system display preferable intelligent cancer cell-specific drug
delivery capacity. We can notice from these studies that heterogeneity of macrophages can
Accepted Article
delivery capacity. We can notice from these studies that heterogeneity of macrophages can
provide new delivery methods and strategies. Whether M2 macrophage, M1 macrophage, or
Accepted Article
provide new delivery methods and strategies. Whether M2 macrophage, M1 macrophage, or
macrophage of other subsets can provide the most satisfactory delivery outcome is uncertain. It
Accepted Article
macrophage of other subsets can provide the most satisfactory delivery outcome is uncertain. It
seems that they are competent in delivering different types of cargoes, because the
Accepted Article
seems that they are competent in delivering different types of cargoes, because the
functionalities and biological behaviors display diversity and huge otherness, which also
Accepted Article
functionalities and biological behaviors display diversity and huge otherness, which also
stimulate great interests and efforts in this field. Current studies in this field are far more enough,
Accepted Article
stimulate great interests and efforts in this field. Current studies in this field are far more enough,
and the underlying mechanisms and potentials remain unclear. Exploiting the heterogeneity of
Accepted Article
and the underlying mechanisms and potentials remain unclear. Exploiting the heterogeneity of
monocyte and macrophage can be challenging meanwhile promising for developing advanced
Accepted Article
monocyte and macrophage can be challenging meanwhile promising for developing advanced
delivery system.
Accepted Article
delivery system.
Since monocytes and macrophages are professional phagocytes, unlike neutrophils that can
Accepted Article
Since monocytes and macrophages are professional phagocytes, unlike neutrophils that can
m NETs for unloading cargoes, it is necessary to solve the problem of drug release when
Accepted Article
m NETs for unloading cargoes, it is necessary to solve the problem of drug release when
Accepted Article
using monocyte/macrophage carriers. We summarized from recent studies that there are about
Accepted Article
using monocyte/macrophage carriers. We summarized from recent studies that there are about
strategies to circumvent this dilemma: 1) restrict the laden cargoes on the cellular surface
Accepted Article
strategies to circumvent this dilemma: 1) restrict the laden cargoes on the cellular surface
This article is protected by copyright. All rights reserved
2.4. Lymphocyte carriers
Trafficking of lymphocytes, including B lymphocyte and T lymphocyte, are important for
integrating and controlling the systemic immune responses and homeostasis.[58] The homing
process of lymphocytes is also regulated by inflammatory and homeostatic chemokines.[59] In
terms of chemokine receptors, lymphocyte is the most complex group of leukocytes and can
differentiate into multiple subsets in response to specific microenvironment. Researchers have
taken advantages of the diversity of lymphocytes to generate cellular vehicle with specific
phenotype for on-demand drug delivery. Rubner‟s group synthesized functional polymer
patches as cellular backpack to load on both B lymphocytes and T lymphocytes.[60] They
demonstrated that these cellular patches did not alter the viability and migration capacity of live
lymphocytes, while could serve as a platform for monitoring their homing to lymphoid tissues,
tumors or infectious sites. Besides, these patches could be doped with magnetic nanoparticles
for manipulating lymphocytes‟ in vivo distribution. While lately, they discovered that the
primarily freely suspended synthetic backpack can also lead to lymphocytes‟ aggregation,
which was dependent on the ratio of cell-to-backpack and the size of the synthetic backpack.[61]
This can be a hindrance that makes it difficult to prepare homogeneous cell based delivery
system, while it can be taken as an opportunity for regulating the functional aggregation of
cells.
Irvine‟s group developed several types of cellular backpack loaded onto T lymphocytes for
tumor-tropic chemotherapy drug delivery and T cell-mediated immunotherapy.[62-65]
Specifically, they generated a type of activated T cells, which can efficiently target lymph node,
for drug loading and active targeting toward lymphoma.[63] Taking into account that during
activation, T cells usually down-regulated lymph node homing molecules, such as CD62L and
CCR7, and reduced lymph node-tropism through mTOR signaling, researchers expanded T
cells in vitro via IL-2 stimulation and retained their targeting moiety through the mTOR
Accepted Article
terms of chemokine receptors, lymphocyte is the most complex group of leukocytes and can
Accepted Article
terms of chemokine receptors, lymphocyte is the most complex group of leukocytes and can
differentiate into multiple subsets in response to specific microenvironment. Researchers have
Accepted Article
differentiate into multiple subsets in response to specific microenvironment. Researchers have
taken advantages of the diversity of lymphocytes to generate cellular vehicle with specific
Accepted Article
taken advantages of the diversity of lymphocytes to generate cellular vehicle with specific
phenotype for on-demand drug delivery. Rubner‟s group synthesized functional polymer
Accepted Article
phenotype for on-demand drug delivery. Rubner‟s group synthesized functional polymer
patches as cellular backpack to load on both B lymphocytes and T lymphocytes.
Accepted Article
patches as cellular backpack to load on both B lymphocytes and T lymphocytes.
demonstrated that these cellular patches did not alter the viability and migration capacity of live
Accepted Article
demonstrated that these cellular patches did not alter the viability and migration capacity of live
lymphocytes, while could serve as a platform for monitoring their homing to lymphoid tissues,
Accepted Article
lymphocytes, while could serve as a platform for monitoring their homing to lymphoid tissues,
tumors or infectious sites. Besides, these patches could be doped with magnetic nanoparticles
Accepted Article
tumors or infectious sites. Besides, these patches could be doped with magnetic nanoparticles
for manipulating lymphocytes‟ in vivo distribution. While lately, they discovered that the
Accepted Article
for manipulating lymphocytes‟ in vivo distribution. While lately, they discovered that the
primarily freely suspended synthetic backpack can also lead to lymphocytes‟ aggregation,
Accepted Article
primarily freely suspended synthetic backpack can also lead to lymphocytes‟ aggregation,
which was dependent on the ratio of cell-
Accepted Article
which was dependent on the ratio of cell-
This can be a hindrance that makes it difficult to prepare homogeneous cell based delivery
Accepted Article
This can be a hindrance that makes it difficult to prepare homogeneous cell based delivery
system, while it can be taken as an opportunity for regulating the functional aggregation of
Accepted Article
system, while it can be taken as an opportunity for regulating the functional aggregation of
Irvine‟s group developed several types of cellular backpack loaded onto T lymphocytes for
Accepted Article
Irvine‟s group developed several types of cellular backpack loaded onto T lymphocytes for
tumor-tropic chemotherapy drug delivery and T cell-mediated immunotherapy.
Accepted Article
tumor-tropic chemotherapy drug delivery and T cell-mediated immunotherapy.
Accepted Article
Specifically, they generated a type of activated T cells, which can efficiently target lymph node,
Accepted Article
Specifically, they generated a type of activated T cells, which can efficiently target lymph node,
This article is protected by copyright. All rights reserved
inhibitor rapamycin to inhibit mTOR signaling. Liposome-based nanocapsules loaded with
SN-38, an active form of camptothecin derivative, were conjugated to the surface of these
lymph node-homing T cells via maleimide-thiol interaction with free cell surface thiol groups.
The authors demonstrated enhanced delivery efficacy and therapeutic performance by T
cell-mediated delivery strategy than free SN-38 and free nanocapsules loaded with SN-38. This
study indicates that specific migration patterns of lymphocytes can be manipulated through
targeting relevant signaling pathways. Further study using this strategy can stem from
exploiting the basic understanding of lymphocytes‟ migration, and may provide multifarious
cell-based delivery modalities.
Addressing the problem of drug release, researchers also exploited cellular processes like
enzyme catalysis of lymphocytes to realize specific event-responsive drug release. For example,
Irvine‟s group linked immunostimulatory drugs release to T cell activation for strengthening T
cell functions in vivo.[65] It is noteworthy that biochemical processes in live cells can be taken
advantages for other purposes more than drug release, such as conversing prodrug into active
forms. Our group has reported a simply modified lymphocyte without genetic intervention for
tumor elimination.[66] Herein, both tumor-targeting as well as biosynthesis capacity of
lymphocytes were taken advantage to promote in vivo therapeutic efficacy of the clinically
used drug molecule, δ-aminolevulinic acid (δ-ALA). Firstly, microfluidic device was used to
incubate lymphocytes with δ-ALA and to isolate δ-ALA-loaded lymphocytes (Figure 4A).[66]
After ex vivo loading with δ-ALA, the adoptively transferred lymphocytes generated
anti-neoplastic drug PpIX through a series of enzymatic reactions and delivered the activated
drug to tumor tissues (Figure 4B).[66] Upon light irradiation, these engineered lymphocytes
underwent apoptosis and disassembled into smaller vesicle, which is apoptotic body loaded
with PpIX. The generated apoptotic body facilitated further penetration deep into tumor tissues
and improved internalization of PpIX by cancer cells. In this study, by taking advantages of the
Accepted Article
cell-mediated delivery strategy than free SN-38 and free nanocapsules loaded with SN-38. This
Accepted Article
cell-mediated delivery strategy than free SN-38 and free nanocapsules loaded with SN-38. This
indicates that specific migration patterns of lymphocytes can be manipulated through
Accepted Article
indicates that specific migration patterns of lymphocytes can be manipulated through
targeting relevant signaling pathways. Further study using this strategy can stem from
Accepted Article
targeting relevant signaling pathways. Further study using this strategy can stem from
oiting the basic understanding of lymphocytes‟ migration, and may provide multifarious
Accepted Article
oiting the basic understanding of lymphocytes‟ migration, and may provide multifarious
cell-based delivery modalities.
Accepted Article
cell-based delivery modalities.
Addressing the problem of drug release, researchers also exploited cellular processes like
Accepted Article
Addressing the problem of drug release, researchers also exploited cellular processes like
enzyme catalysis of lymphocytes to realize specific event-responsive drug release. For example,
Accepted Article
enzyme catalysis of lymphocytes to realize specific event-responsive drug release. For example,
vine‟s group linked immunostimulatory drugs release to T cell activation for strengthening T
Accepted Article
vine‟s group linked immunostimulatory drugs release to T cell activation for strengthening T
cell functions in vivo.
Accepted Article
cell functions in vivo.
[65]
Accepted Article
[65]
advantages for other purposes more than drug release, such as conversing prodrug into active
Accepted Article
advantages for other purposes more than drug release, such as conversing prodrug into active
forms. Our group has reported a simply modified lymphocyte without genetic intervention for
Accepted Article
forms. Our group has reported a simply modified lymphocyte without genetic intervention for
tumor elimination.
Accepted Article
tumor elimination.
[66]
Accepted Article
[66]
Herein, both tumor-targeting as well as biosynthesis capacity of
Accepted Article
Herein, both tumor-targeting as well as biosynthesis capacity of
Accepted Article
lymphocytes were taken advantage to promote in vivo therapeutic efficacy of the clinically
Accepted Article
lymphocytes were taken advantage to promote in vivo therapeutic efficacy of the clinically
used drug molecule, δ-aminolevulinic acid (δ-ALA). Firstly, microfluidic device was used to
Accepted Article
used drug molecule, δ-aminolevulinic acid (δ-ALA). Firstly, microfluidic device was used to
incubate lymphocytes with δ-ALA and to isolate δ-ALA-loaded lymphocytes
Accepted Article
incubate lymphocytes with δ-ALA and to isolate δ-ALA-loaded lymphocytes
After ex vivo loading with δ-ALA, the adoptively transferred lymphocytes generated
Accepted Article
After ex vivo loading with δ-ALA, the adoptively transferred lymphocytes generated
Accepted Article
i-neoplastic drug PpIX through a series of enzymatic reactions and delivered the activated
Accepted Article
i-neoplastic drug PpIX through a series of enzymatic reactions and delivered the activated
This article is protected by copyright. All rights reserved
biochemical processes of lymphocytes, therapeutic agent experienced two transformation
stages: 1) inactive prodrug δ-ALA to active photosensitizer PpIX, and 2) PpIX trapped in cells
to PpIX loading in penetrable small vesicles.
Since lymphocytes possess potent immunological functions including cell-mediated
cytotoxicity and cytokine/antibody production, major efforts in studying lymphocytes have
been directed to developing advance cell-based medicine and immunological therapeutics.
Strategy of lymphocyte-based delivery system for drug and synthetic materials should combine
with the novel cell therapy for improving the clinical translation of these bio-hybrid systems.
2.5. Stem cell carriers
Stem cells have many detailed classifications, and generally represent cells with self-renewal
and differentiation capacities. Haematopoietic stem cells (HSCs) and mesenchymal
stem/stromal cells (MSCs) are the first-generation therapeutic stem cells that have been
reported for clinical usage quite early before.[67-68] In recent years, stem cells and stem
cell-based carriers have been applied in treatments for not only endogenous injury but also
tumors.[69] Therapeutic stem cells also display tumor tropism,[70] therefore, they are currently
taken as „Trojan horses‟ for delivering therapeutic agents toward malignant tumors. The
tumor-tropism of stem cell usually depends on their surface receptors, which sense the
gradients of chemokine and cytokine, leading stem cells migrate toward tumor tissues that
released multiple chemoattractant. For example, Luo et al utilized MSCs as carriers to
internalize and deliver biocompatible poly (lactic-co-glycolic acid)/black phosphorus quantum
dots (PLGA/BPQDs) toward subcutaneous glioma tumor for photothermal therapy.[71] This
migration capacity relies on the surface receptor CXCR4 of MSCs, which directs MSCs to
migrate toward tumor tissues that release high concentration of chemokine such as stromal
derived factor 1. The authors demonstrated the enhanced maintenance of PLGA/BPQDs within
MSCs in vitro and improved retention within tumor tissues in vivo through using MCSs carrier.
Accepted Article
cytotoxicity and cytokine/antibody production, major efforts in studying lymphocytes have
Accepted Article
cytotoxicity and cytokine/antibody production, major efforts in studying lymphocytes have
been directed to developing advance cell-based medicine and immunological therapeutics.
Accepted Article
been directed to developing advance cell-based medicine and immunological therapeutics.
Strategy of lymphocyte-based delivery system for drug and synthetic materials should combine
Accepted Article
Strategy of lymphocyte-based delivery system for drug and synthetic materials should combine
with the novel cell therapy for improving the clinical translation of these bio-hybrid systems.
Accepted Article
with the novel cell therapy for improving the clinical translation of these bio-hybrid systems.
2.5. Stem cell carriers
Accepted Article
2.5. Stem cell carriers
Stem cells have many detailed classifications, and generally represent cells with self-renewal
Accepted Article
Stem cells have many detailed classifications, and generally represent cells with self-renewal
and differentiation capacities. Haematopoietic stem cells (HSCs) and mesenchymal
Accepted Article
and differentiation capacities. Haematopoietic stem cells (HSCs) and mesenchymal
stem/stromal cells (MSCs) are the first-generation therapeutic stem cells that have been
Accepted Article
stem/stromal cells (MSCs) are the first-generation therapeutic stem cells that have been
reported for clinical usage quite early before.
Accepted Article
reported for clinical usage quite early before.
cell-based carriers have been applied in treatments for not only endogenous injury but also
Accepted Article
cell-based carriers have been applied in treatments for not only endogenous injury but also
[69]
Accepted Article
[69]
Therapeutic stem cells also display tumor tropism,
Accepted Article
Therapeutic stem cells also display tumor tropism,
taken as „Trojan horses‟ for delivering therapeutic agents toward malignant tumors. The
Accepted Article
taken as „Trojan horses‟ for delivering therapeutic agents toward malignant tumors. The
or-tropism of stem cell usually depends on their surface receptors, which sense the
Accepted Article
or-tropism of stem cell usually depends on their surface receptors, which sense the
gradients of chemokine and cytokine, leading stem cells migrate toward tumor tissues that
Accepted Article
gradients of chemokine and cytokine, leading stem cells migrate toward tumor tissues that
Accepted Article
leased multiple chemoattractant. For example, Luo et al utilized MSCs as carriers to
Accepted Article
leased multiple chemoattractant. For example, Luo et al utilized MSCs as carriers to
internalize and deliver biocompatible poly (lactic-
Accepted Article
internalize and deliver biocompatible poly (lactic-
Accepted Article
dots (PLGA/BPQDs) toward subcutaneous glioma tumor for photothermal therapy.
Accepted Article
dots (PLGA/BPQDs) toward subcutaneous glioma tumor for photothermal therapy.
This article is protected by copyright. All rights reserved
Besides active tumor targeting, the authors also noted that the intravenously injected MCSs
tended to be trapped in lungs.[71] This phenomena has also been demonstrated and exploited for
lung cancer targeted delivery by other researchers.[72]
Shah‟s group have demonstrated that MSCs can home to tumor metastasis in brain, and have
taken this property for delivering bio-agent oncolytic virus.[73-75] The authors adjusted the
infection ratio of oncolytic herpes simplex virus (oHSV) to MSCs to obtain the optimal
delivery system MSC-oHSV.[75] They found that with a multiplicity of infection value of 1,
MSC-oHSV can survive more than 4 days meanwhile displayed better oHSV loading capacity.
Through internal carotid artery injection, MSC-oHSV can reach metastatic melanoma tumor in
brain as early as 24 hours after injection, and continuously recruited during subsequent 4 days.
However, the authors also found that MSC-oHSV mostly accumulated in the lung via
intravenous injection. This result suggest that the injection method and location will influence
the bio-distribution of re-perfused cells.
To solve the problem of stem cells‟ lung residence and reprogram the in vivo bio-distribution,
Liu and coworkers have developed a bispecific antibody termed PT-BsAbs to realize in situ
conjugation of HSCs and platelet.[76] The authors modified the platelet binding ligand CD42b
with tetrazine(TZ)-polyethylene glycol-NHS to obtain CD42b-TZ, and also cojungated the
HSCs targeting moiety CD34 with trans-cyclooctene(TCO)-polyethylene glycol-NHS
togenerate CD34-TCO. Through TZ and TCO conjugation, CD34 and CD42b were linked to
provide bispecific PT-BsAbs. Upon inhalation, PT-BsAbs mostly accumulated in the lungs and
simultaneously targeted HSCs and platelets and linked these two cells together. Thereafter,
platelets can help direct HSCs toward endogenous injured sites and help improve the treatment
of myocardial infarction. Using platelets to improve stem cells‟ bio-distribution is also reported
by Gu‟s group.[77]
Zhang et al also reported a nanomaterial-based strategy to improve the targeting capacity of
Accepted Article
taken this property for delivering bio-agent oncolytic virus.
Accepted Article
taken this property for delivering bio-agent oncolytic virus.
infection ratio of oncolytic herpes simplex virus (oHSV) to MSCs to obtain the optimal
Accepted Article
infection ratio of oncolytic herpes simplex virus (oHSV) to MSCs to obtain the optimal
delivery system MSC-oHSV.
Accepted Article
delivery system MSC-oHSV.
MSC-oHSV can survive more than 4 days meanwhile displayed better oHSV loading capacity.
Accepted Article
MSC-oHSV can survive more than 4 days meanwhile displayed better oHSV loading capacity.
Through internal carotid artery injection, MSC-oHSV can reach metastatic melanoma tumor in
Accepted Article
Through internal carotid artery injection, MSC-oHSV can reach metastatic melanoma tumor in
brain as early as 24 hours after injection, and continuously recruited during subsequent 4 days.
Accepted Article
brain as early as 24 hours after injection, and continuously recruited during subsequent 4 days.
ever, the authors also found that MSC-oHSV mostly accumulated in the lung via
Accepted Article
ever, the authors also found that MSC-oHSV mostly accumulated in the lung via
intravenous injection. This result suggest that the injection method and location will influence
Accepted Article
intravenous injection. This result suggest that the injection method and location will influence
the bio-distribution of re-perfused cells.
Accepted Article
the bio-distribution of re-perfused cells.
To solve the problem of stem cells‟ lung residence and reprogram the in vivo bio-distribution,
Accepted Article
To solve the problem of stem cells‟ lung residence and reprogram the in vivo bio-distribution,
Liu and coworkers have developed a bispecific antibody termed PT-BsAbs to realize in situ
Accepted Article
Liu and coworkers have developed a bispecific antibody termed PT-BsAbs to realize in situ
conjugation of HSCs and platelet.
Accepted Article
conjugation of HSCs and platelet.
with tetrazine(TZ)-polyethylene glycol-NHS to obtain CD42b-TZ, and also cojungated the
Accepted Article
with tetrazine(TZ)-polyethylene glycol-NHS to obtain CD42b-TZ, and also cojungated the
HSCs targeting moiety CD34 with trans-cyclooctene(TCO)-polyethylene glycol-NHS
Accepted Article
HSCs targeting moiety CD34 with trans-cyclooctene(TCO)-polyethylene glycol-NHS
togenerate CD34-TCO. Through TZ and TCO conjugation, CD34 and CD42b were linked to
Accepted Article
togenerate CD34-TCO. Through TZ and TCO conjugation, CD34 and CD42b were linked to
Accepted Article
provide bispecific PT-BsAbs. Upon inhalation, PT-BsAbs mostly accumulated in the lungs and
Accepted Article
provide bispecific PT-BsAbs. Upon inhalation, PT-BsAbs mostly accumulated in the lungs and
simultaneously targeted HSCs and platelets and linked these two cells together. Thereafter,
Accepted Article
simultaneously targeted HSCs and platelets and linked these two cells together. Thereafter,
This article is protected by copyright. All rights reserved
MSCs.[78] They devised a magnetosome-like 1D ferrimagnetic iron oxide nanochains (MFIONs)
through self-assembly method. The as-designed MFIONs are more favorable for cellular
uptake, and thus improve gene transfection in stem cells. Besides, with higher cellular uptake,
MFIONs can release high concentration of ferrous irons to stimulate upregulation of
homing-related receptor CXCR4 in MSCs, thereby improving the accumulation and
therapeutic performances of MSCs within injured brain. Besides, there are other research also
utilized superparamagnetic iron oxide nanoparticle to integrate with stem cells for
magnet-guided targeting.[79]
Kim et al modified human MSCs (hMSCs) with dibenzocyclooctyne-polyethylene
glycol(PEG)-pheophorbide A conjugates (DPP) through click chemistry for active delivery
toward tumors and photodynamic therapy (PDT).[80] The authors demonstrated that after PDT
stimulation, hMSCs-DPP can release pro-inflammatory cytokines like heat shock protein 70
and induce anti-tumor immune response. This study also prompted another advantage of stem
cell based carrier, which is the cell death of this cellluar vehicle can be exploited for activation
of immune responses and may provide therapeutic benefits. Besides, it is noteworthy that, in
comparison with free nanoparticles DPP, hMSCs improved the final concentration of DPP in
tumor tissues, which took a longer time of about 2 to 4 days. This result suggests a feature of
stem cell carrier, which is, it may take a longer time for stem cell carrier to realize higher
accumulation at tumor tissues than nanoscale delivery system. And this feature can be a
challenge and needs delicate construction to insure longer retention as well as benign integrity
of loaded cargoes in stem cell carrier.
In summary, stem-cell based carrier possess active migration capacity via sensing the
gradients of chemokine and cytokines, thus can be taken as vehicle for delivering drugs and
bioactive therapeutics and targeting toward injured tissues and tumors.[81-83] Stem cell-based
carrier display several preferable characters, including therapeutic potential for regenerative
Accepted Article
homing-related receptor
Accepted Article
homing-related receptor
therapeutic performances of MSCs within injured brain. Besides, there are other research also
Accepted Article
therapeutic performances of MSCs within injured brain. Besides, there are other research also
lized superparamagnetic iron oxide nanoparticle to integrate with stem cells for
Accepted Article
lized superparamagnetic iron oxide nanoparticle to integrate with stem cells for
magnet-guided targeting.
Accepted Article
magnet-guided targeting.
Kim et al