Targeted repair of heart injury by stem cells fused with platelet nanovesicles

Targeted Delivery of a Matrix Metalloproteinases-2 Specific Inhibitor Using Multifunctional Nanogels to Attenuate Ischemic Skeletal Muscle Degeneration and Promote Revascularization

Critical limb ischemia (CLI) is a severe form of peripheral artery disease (PAD). It is featured by degenerated skeletal muscle and poor vascularization. During the development of CLI, the upregulated matrix metalloproteinase-2 (MMP-2) degrades muscle extracellular matrix to initiate the degeneration. Meanwhile, MMP-2 is necessary for blood vessel formation. It is thus hypothesized that appropriate MMP-2 bioactivity in ischemic limbs will not only attenuate muscle degeneration but also promote blood vessel formation. Herein, we developed ischemia-targeting poly(N-isopropylacrylamide)-based nanogels to specifically deliver an MMP-2 inhibitor CTTHWGFTLC (CTT) into ischemic limbs to tailor MMP-2 bioactivity. Besides acting as an MMP-2 inhibitor, CTT promoted endothelial cell migration under conditions mimicking the ischemic limbs. The nanogels were sensitive to the pH of ischemic tissues, allowing them to largely aggregate in the injured area. To help reduce nanogel uptake by macrophages and increase circulation time, the nanogels were cloaked with a platelet membrane. An ischemia-targeting peptide CSTSMLKA (CST) was further conjugated on the platelet membrane for targeted delivery of nanogels into the ischemic area. CTT gradually released from the nanogels for 4 weeks. The nanogels mostly accumulated in the ischemic area for 28 days. The released CTT preserved collagen in the muscle and promoted its regeneration. In addition, CTT stimulated angiogenesis. Four weeks after CLI, the blood flow and vessel density of the ischemic limbs treated with the nanogels were remarkably higher than the control groups without CTT release. These results demonstrate that the developed nanogel-based CTT release system has the potential to stimulate ischemic limb regeneration.

Cell primitive-based biomimetic functional materials for enhanced cancer therapy

Cell primitive-based functional materials that combine the advantages of natural substances and nanotechnology have emerged as attractive therapeutic agents for cancer therapy. Cell primitives are characterized by distinctive biological functions, such as long-term circulation, tumor specific targeting, immune modulation etc. Moreover, synthetic nanomaterials featuring unique physical/chemical properties have been widely used as effective drug delivery vehicles or anticancer agents to treat cancer. The combination of these two kinds of materials will catalyze the generation of innovative biomaterials with multiple functions, high biocompatibility and negligible immunogenicity for precise cancer therapy. In this review, we summarize the most recent advances in the development of cell primitive-based functional materials for cancer therapy. Different cell primitives, including bacteria, phages, cells, cell membranes, and other bioactive substances are introduced with their unique bioactive functions, and strategies in combining with synthetic materials, especially nanoparticulate systems, for the construction of function-enhanced biomaterials are also summarized. Furthermore, foreseeable challenges and future perspectives are also included for the future research direction in this field.

Trends of nanotechnology in type 2 diabetes mellitus treatment

There are several therapeutic approaches in type 2 diabetes mellitus (T2DM). When diet and exercise fail to control hyperglycemia, patients are forced to start therapy with antidiabetic agents. However, these drugs present several drawbacks that can affect the course of treatment. The major disadvantages of current oral modalities for the treatment of T2DM are mainly depicted in the low bioavailability and the immediate release of the drug, generating the need for an increase in frequency of dosing. In conjugation with the manifestation of adverse side effects, patient compliance to therapy is reduced. Over the past few years nanotechnology has found fertile ground in the development of novel delivery modalities that can potentially enhance anti-diabetic regimes efficacy. All efforts have been targeted towards two main vital steps: (a) to protect the drug by encapsulating it into a nano-carrier system and (b) efficiently release the drug in a gradual as well as controllable manner. However, only a limited number of studies published in the literature used in vivo techniques in order to support findings. Here we discuss the current disadvantages of modern T2DM marketed drugs, and the nanotechnology advances supported by in vivo in mouse/rat models of glucose homeostasis. The generation of drug nanocarriers may increase bioavailability, prolong release and therefore reduce dosing and thus, improve patient compliance. This novel approach might substantially improve quality of life for diabetics. Application of metal nanoformulations as indirect hypoglycemic agents is also discussed.

Targeted delivery of extracellular vesicles in heart injury

Extracellular vesicles (EVs) are nanoscale extracellular vesicles derived from endocytosis that are crucial to intercellular communication. EVs possess natural biocompatibility and stability that allow them to cross biological membranes and that protect them from degradation. Recent studies have shown that EVs-mediated crosstalk between different cell types in the heart could play important roles in the maintenance of cardiac homeostasis and the pathogenesis of heart diseases. In particular, EVs secreted by different types of stem cells exhibit cardioprotective effects. However, numerous studies have shown that intravenously injected EVs are quickly cleared by macrophages of the mononuclear phagocyte system (MPS) and preferentially accumulate in MPS organs such as the liver, spleen, and lung. In this review, we discuss exosome biogenesis, the role of EVs in heart diseases, and challenges in delivering EVs to the heart. Furthermore, we extensively discuss the targeted delivery of EVs for treating ischemic heart disease. These understandings will aid in the development of effective treatment strategies for heart diseases.

Recent Development in Therapeutic Cardiac Patches

For the past decades, heart diseases remain the leading cause of death worldwide. In the adult mammalian heart, damaged cardiomyocytes will be replaced by non-contractile fibrotic scar tissues due to the poor regenerative ability of heart, causing heart failure subsequently. The development of tissue engineering has launched a new medical innovation for heart regeneration. As one of the most outstanding technology, cardiac patches hold the potential to restore cardiac function clinically. Consisted of two components: therapeutic ingredients and substrate scaffolds, the fabrication of cardiac patches requires both advanced bioactive molecules and biomaterials. In this review, we will present the most state-of-the-art cardiac patches and analysis their compositional details. The therapeutic ingredients will be discussed from cell sources to bioactive molecules. In the meanwhile, the recent advances to obtain scaffold biomaterials will be highlighted, including synthetic and natural materials. Also, we have focused on the challenges and potential strategies to fabricate clinically applicable cardiac patches.

Cardiac Stromal Cell Patch Integrated with Engineered Microvessels Improves Recovery from Myocardial Infarction in Rats and Pigs

The vascularized cardiac patch strategy is promising for ischemic heart repair after myocardial infarction (MI), but current fabrication processes are quite complicated. Vascularized cardiac patches that can promote concurrent restoration of both the myocardium and vasculature at the injured site in a large animal model remain elusive. The safety and therapeutic benefits of a cardiac stromal cell patch integrated with engineered biomimetic microvessels (BMVs) were determined for treating MI. By leveraging a microfluidic method employing hydrodynamic focusing, we constructed the endothelialized microvessels and then encapsulated them together with therapeutic cardiosphere-derived stromal cells (CSCs) in a fibrin gel to generate a prevascularized cardiac stromal cell patch (BMV-CSC patch). We showed that BMV-CSC patch transplantation significantly promoted cardiac function, reduced scar size, increased viable myocardial tissue, promoted neovascularization, and suppressed inflammation in rat and porcine MI models, demonstrating enhanced therapeutic efficacy compared to conventional cardiac stromal cell patches. BMV-CSC patches did not increase renal and hepatic toxicity or exhibit immunogenicity. We noted a significant increase in endogenous progenitor cell recruitment to the peri-infarct region of the porcine hearts treated with BMV-CSC patch as compared to those that received control treatments. These findings establish the BMV-CSC patch as a novel engineered-tissue therapeutic for ischemic tissue repair.

Development of Magnet-Driven and Image-Guided Degradable Microrobots for the Precise Delivery of Engineered Stem Cells for Cancer Therapy

Precise delivery of therapeutic cells to the desired site in vivo is an emerging and promising cellular therapy in precision medicine. This paper presents the development of a magnet-driven and image-guided degradable microrobot that can precisely deliver engineered stem cells for orthotopic liver tumor treatment. The microrobot employs a burr-like porous sphere structure and is made with a synthesized composite to fulfill degradability, mechanical strength, and magnetic actuation capability simultaneously. The cells can be spontaneously released from the microrobots on the basis of the optimized microrobot structure. The microrobot is actuated by a gradient magnetic field and guided by a unique photoacoustic imaging technology. In preclinical experiments on nude mice, microrobots carrying cells are injected via the portal vein and the released cells from the microrobots can inhibit the tumor growth greatly. This paper reveals for the first time of using degradable microrobots for precise delivery of therapeutic cells in vascular tissue and demonstrates its therapeutic effect in preclinical test.

Biomaterials Loaded with Growth Factors/Cytokines and Stem Cells for Cardiac Tissue Regeneration

Myocardial infarction causes cardiac tissue damage and the release of damage-associated molecular patterns leads to activation of the immune system, production of inflammatory mediators, and migration of various cells to the site of infarction. This complex response further aggravates tissue damage by generating oxidative stress, but it eventually heals the infarction site with the formation of fibrotic tissue and left ventricle remodeling. However, the limited self-renewal capability of cardiomyocytes cannot support sufficient cardiac tissue regeneration after extensive myocardial injury, thus, leading to an irreversible decline in heart function. Approaches to improve cardiac tissue regeneration include transplantation of stem cells and delivery of inflammation modulatory and wound healing factors. Nevertheless, the harsh environment at the site of infarction, which consists of, but is not limited to, oxidative stress, hypoxia, and deficiency of nutrients, is detrimental to stem cell survival and the bioactivity of the delivered factors. The use of biomaterials represents a unique and innovative approach for protecting the loaded factors from degradation, decreasing side effects by reducing the used dosage, and increasing the retention and survival rate of the loaded cells. Biomaterials with loaded stem cells and immunomodulating and tissue-regenerating factors can be used to ameliorate inflammation, improve angiogenesis, reduce fibrosis, and generate functional cardiac tissue. In this review, we discuss recent findings in the utilization of biomaterials to enhance cytokine/growth factor and stem cell therapy for cardiac tissue regeneration in small animals with myocardial infarction.

Mesenchymal stem cells-derived and siRNAs-encapsulated exosomes inhibit osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) is a progressive, obstinate and disabling disease. At present, the treatment of ONFH is still a global medical problem. We aim to explore the role of bone mesenchymal stem cells (BMSCs)‐derived and siRNAs‐encapsulated exosomes (siRNAs‐encapsulated BMSCexos) in ONFH. We first isolated BMSCexos and screened siRNAs of 6 ONFH‐related genes for siRNAs‐encapsulated BMSCexo. The expression of these 6 ONFH‐related genes in dexamethasone (DXM)‐treated MC3T3‐E1 cell, cell model of ONFH, was detected by RT‐qPCR and Western blot analysis. And then, we performed CCK‐8 assay, angiogenesis assay and HE staining analysis to test the promotion role of the siRNAs‐encapsulated BMSCexo for angiogenesis during ONFH repair. The results suggest that the obtained particles were BMSCexos. The screened effective siRNAs could effectively knock down their expression in VECs. Moreover, siRNAs‐encapsulated BMSCexo could effectively knock down the expression of these genes in VECs. In addition, siRNAs‐encapsulated BMSCexo promote angiogenesis during ONFH repair. In conclusion, we found siRNAs‐encapsulated BMSCexos could promote ONFH repair by angiogenesis, and indicated exosome as the new siRNA carrier is of great significance to improve the efficiency of RNAi.

Nanomedicine Approaches for Advanced Diagnosis and Treatment of Atherosclerosis and Related Ischemic Diseases

Cardiovascular diseases (CVDs) remain one of the major causes of mortality worldwide. In response to this and other worldwide health epidemics, nanomedicine has emerged as a rapidly evolving discipline that involves the development of innovative nanomaterials and nanotechnologies and their applications in therapy and diagnosis. Nanomedicine presents unique advantages over conventional medicines due to the superior properties intrinsic to nanoscopic therapies. Once used mainly for cancer therapies, recently, tremendous progress has been made in nanomedicine that has led to an overall improvement in the treatment and diagnosis of CVDs. This review elucidates the pathophysiology and potential targets of atherosclerosis and associated ischemic diseases. It may be fruitful to pursue future work in the nanomedicine-mediated treatment of CVDs based on these targets. A comprehensive overview is then provided featuring the latest preclinical and clinical outcomes in cardiovascular imaging, biomarker detection, tissue engineering, and nanoscale delivery, with specific emphasis on nanoparticles, nanostructured scaffolds, and nanosensors. Finally, the challenges and opportunities regarding the future development and clinical translation of nanomedicine in related fields are discussed. Overall, this review aims to provide a deep and thorough understanding of the design, application, and future development of nanomedicine for atherosclerosis and related ischemic diseases.

Cell membrane biomimetic nanoparticles for inflammation and cancer targeting in drug delivery

Nanoparticle capture and elimination by the immune system are great obstacles for drug delivery. Camouflaging nanoparticles with cell membrane represents a promising strategy to communicate and negotiate with the immune system. As a novel class of nanotherapeutics, such biomimetic nanoparticles inherit specific biological functionalities of the source cells (e.g., erythrocytes, immune cells, cancer cells and platelets) in order to evade immune elimination, prolong circulation time, and even target a disease region by virtue of the homing tendency of the cell membrane protein. In this review, we begin with an overview of different cell membranes that can be utilized to create a biointerface on nanoparticles. Subsequently, we elaborate on the state-of-the-art of cell membrane biomimetic nanoparticles for drug delivery. In particular, a summary of data on circulation capacity and targeting efficiency by camouflaged nanoparticles is presented. In addition to cancer therapy, inflammation treatment, as an emerging application of biomimetic nanoparticles, is specifically included. The challenges and outlook of this technology are discussed.

Cell Membrane-Based Biomimetic Nanoparticles and the Immune System: Immunomodulatory Interactions to Therapeutic Applications

Nanoparticle-based drug delivery systems have been synthesized from a wide array of materials. The therapeutic success of these platforms hinges upon their ability to favorably interact with the biological environment (both systemically and locally) and recognize the diseased target tissue. The immune system, composed of a highly coordinated organization of cells trained to recognize foreign bodies, represents a key mediator of these interactions. Although components of this system may act as a barrier to nanoparticle (NP) delivery, the immune system can also be exploited to target and trigger signaling cues that facilitate the therapeutic response stemming from systemic administration of NPs. The nano-bio interface represents the key facilitator of this communication exchange, where the surface properties of NPs govern their in vivo fate. Cell membrane-based biomimetic nanoparticles have emerged as one approach to achieve targeted drug delivery by actively engaging and communicating with the biological milieu. In this review, we will highlight the relationship between these biomimetic nanoparticles and the immune system, emphasizing the role of tuning the nano-bio interface in the immunomodulation of diseases. We will also discuss the therapeutic applications of this approach with biomimetic nanoparticles, focusing on specific diseases ranging from cancer to infectious diseases. Lastly, we will provide a critical evaluation on the current state of this field of cell membrane-based biomimetic nanoparticles and its future directions in immune-based therapy.

Targeted Delivery of Mesenchymal Stem Cell-Derived Nanovesicles for Spinal Cord Injury Treatment

Due to the safety issues and poor engraftment of mesenchymal stem cell (MSC) implantation, MSC-derived exosomes have been spotlighted as an alternative therapy for spinal cord injury (SCI). However, insufficient productivity of exosomes limits their therapeutic potential for clinical application. Moreover, low targeting ability of unmodified exosomes is a critical obstacle for their further applications as a therapeutic agent. In the present study, we fabricated macrophage membrane-fused exosome-mimetic nanovesicles (MF-NVs) from macrophage membrane-fused umbilical cord blood-derived MSCs (MF-MSCs) and confirmed their therapeutic potential in a clinically relevant mouse SCI model (controlled mechanical compression injury model). MF-NVs contained larger quantity of ischemic region-targeting molecules compared to normal MSC-derived nanovesicles (N-NVs). The targeting molecules in MF-NVs, which were derived from macrophage membranes, increased the accumulation of MF-NVs in the injured spinal cord after the in vivo systemic injection. Increased accumulation of MF-NVs attenuated apoptosis and inflammation, prevented axonal loss, enhanced blood vessel formation, decreased fibrosis, and consequently, improved spinal cord function. Synthetically, we developed targeting efficiency-potentiated exosome-mimetic nanovesicles and present their possibility of clinical application for SCI.

Particle-based artificial three-dimensional stem cell spheroids for revascularization of ischemic diseases

Development of new approaches to biomimetically reconstruct vasculature networks remains challenging in regenerative medicine. We introduce a particle-based artificial stem cell spheroid (ASSP) technology that recapitulates paracrine functions of three-dimensional (3D) SSPs for vasculature regeneration. Specifically, we used a facile method to induce the aggregation of stem cells into 3D spheroids, which benefited from hypoxia microenvironment-driven and enhanced secretion of proangiogenic bioactive factors. Furthermore, we artificially reconstructed 3D spheroids (i.e., ASSP) by integration of SSP-secreted factors into micro-/nanoparticles with cell membrane-derived surface coatings. The easily controllable sizes of the ASSP particles provided superior revascularization effects on the ischemic tissues in hindlimb ischemia models through local administration of ASSP microparticles and in myocardial infarction models via the systemic delivery of ASSP nanoparticles. The strategy offers a promising therapeutic option for ischemic tissue regeneration and addresses issues faced by the bottlenecked development in the delivery of stem cell therapies.

Next-generation stem cells - ushering in a new era of cell-based therapies

Naturally occurring stem cells isolated from humans have been used therapeutically for decades. This has primarily involved the transplantation of primary cells such as haematopoietic and mesenchymal stem cells and, more recently, derivatives of pluripotent stem cells. However, the advent of cell-engineering approaches is ushering in a new generation of stem cell-based therapies, greatly expanding their therapeutic utility. These next-generation stem cells are being used as 'Trojan horses' to improve the delivery of drugs and oncolytic viruses to intractable tumours and are also being engineered with angiogenic, neurotrophic and anti-inflammatory molecules to accelerate the repair of injured or diseased tissues. Moreover, gene therapy and gene editing technologies are being used to create stem cell derivatives with improved functionality, specificity and responsiveness compared with their natural counterparts. Here, we review these engineering approaches and areas in which they will help broaden the utility and clinical applicability of stem cells.

Engineering better stem cell therapies for treating heart diseases

For decades, stem cells and their byproducts have shown efficacy in repairing tissues and organs in numerous pre-clinical studies and some clinical trials, providing hope for possible cures for many important diseases. However, the translation of stem cell therapy for heart diseases from bench to bed is still hampered by several limitations. The therapeutic benefits of stem cells are mediated by a combo of mechanisms. In this review, we will provide a brief summary of stem cell therapies for ischemic heart disease. Basically, we will talk about these barriers for the clinical application of stem cell-based therapies, the investigation of mechanisms behind stem-cell based cardiac regeneration and also, what bioengineers can do and have been doing on the translational stage of stem cell therapies for heart repair.

Ligand-Installed Nanocarriers toward Precision Therapy

Development of drug-delivery systems that selectively target neoplastic cells has been a major goal of nanomedicine. One major strategy for achieving this milestone is to install ligands on the surface of nanocarriers to enhance delivery to target tissues, as well as to enhance internalization of nanocarriers by target cells, which improves accuracy, efficacy, and ultimately enhances patient outcomes. Herein, recent advances regarding the development of ligand-installed nanocarriers are introduced and the effect of their design on biological performance is discussed. Besides academic achievements, progress on ligand-installed nanocarriers in clinical trials is presented, along with the challenges faced by these formulations. Lastly, the future perspectives of ligand-installed nanocarriers are discussed, with particular emphasis on their potential for emerging precision therapies.

Targeted anti-IL-1β platelet microparticles for cardiac detoxing and repair

An acute myocardial infarction (AMI) induces a sterile inflammatory response that facilitates further heart injury and promotes adverse cardiac remodeling. Interleukin-1β (IL-1β) plays a central role in the sterile inflammatory response that results from AMI. Thus, IL-1β blockage is a promising strategy for treatment of AMI. However, conventional IL-1β blockers lack targeting specificity. This increases the risk of serious side effects. To address this problem herein, we fabricated platelet microparticles (PMs) armed with anti-IL-1β antibodies to neutralize IL-1β after AMI and to prevent adverse cardiac remodeling. Our results indicate that the infarct-targeting PMs could bind to the injured heart, increasing the number of anti-IL-1β antibodies therein. The anti-IL-1β platelet PMs (IL1-PMs) protect the cardiomyocytes from apoptosis by neutralizing IL-1β and decreasing IL-1β-driven caspase-3 activity. Our findings indicate that IL1-PM is a promising cardiac detoxification agent that removes cytotoxic IL-1β during AMI and induces therapeutic cardiac repair.

Utilization of Human Induced Pluripotent Stem Cells for Cardiac Repair

The paracrine effect, mediated by chemical signals that induce a physiological response on neighboring cells in the same tissue, is an important regenerative mechanism for stem cell-based therapy. Exosomes are cell-secreted nanovesicles (50–120 nm) of endosomal origin, and have been demonstrated to be a major contributor to the observed stem cell-mediated paracrine effect in the cardiac repair process. Following cardiac injury, exosomes deriving from exogenous stem cells have been shown to regulate cell apoptosis, proliferation, angiogenesis, and fibrosis in the infarcted heart. Exosomes also play a crucial role in the intercellular communication between donor and recipient cells. Human induced pluripotent stem cells (hiPSCs) are promising cell sources for autologous cell therapy in regenerative medicine. Here, we review recent advances in the field of progenitor-cell derived, exosome-based cardiac repair, with special emphasis on exosomes derived from hiPSCs.

Bispecific Antibody Inhalation Therapy for Redirecting Stem Cells from the Lungs to Repair Heart Injury

Stem cell therapy is a promising strategy for cardiac repair. However, clinical efficacy is hampered by poor cell engraftment and the elusive repair mechanisms of the transplanted stem cells. The lung is a reservoir of hematopoietic stem cells (HSCs) and a major biogenesis site for platelets. A strategy is sought to redirect lung resident stem cells to the injured heart for therapeutic repair after myocardial infarction (MI). To achieve this goal, CD34-CD42b platelet-targeting bispecific antibodies (PT-BsAbs) are designed to simultaneously recognize HSCs (via CD34) and platelets (via CD42b). After inhalation delivery, PT-BsAbs reach the lungs and conjoined HSCs and platelets. Due to the innate injury-finding ability of platelets, PT-BsAbs guide lung HSCs to the injured heart after MI. The redirected HSCs promote endogenous repair, leading to increased cardiac function. The repair mechanism involves angiomyogenesis and inflammation modulation. In addition, the inhalation route is superior to the intravenous route to deliver PT-BsAbs in terms of the HSCs' homing ability and therapeutic benefits. This work demonstrates that this novel inhalable antibody therapy, which harnesses platelets derived from the lungs, contributes to potent stem cell redirection and heart repair. This strategy is safe and effective in a mouse model of MI.

Exosome and Biomimetic Nanoparticle Therapies for Cardiac Regenerative Medicine

Exosomes and biomimetic nanoparticles have great potential to develop into a wide-scale therapeutic platform within the regenerative medicine industry. Exosomes, a subgroup of EVs with diameter ranging from 30-100 nm, have recently gained attention as an innovative approach for the treatment of various diseases, including heart disease. Their beneficial factors and regenerative properties can be contrasted with various cell types. Various biomimetic nanoparticles have also emerged as a unique platform in regenerative medicine. Biomimetic nanoparticles are a drug delivery platform, which have the ability to contain both biological and fabricated components to improve therapeutic efficiency and targeting. The novelty of these platforms holds promise for future clinical translation upon further investigation. In order for both exosome therapeutics and biomimetic nanoparticles to translate into large-scale clinical treatment, numerous factors must first be considered and improved. Standardization of different protocols, from exosome isolation to storage conditions, must be optimized to ensure batches are pure. Standardization is also important to ensure no variability in this process across studies, thus making it easier to interpret data across different disease models and treatments. Expansion of clinical trials incorporating both biomimetic nanoparticles and exosomes will require a standardization of fabrication and isolation techniques, as well as stricter regulations to ensure reproducibility across various studies and disease models. This review will summarize current research on exosome therapeutics and the application of biomimetic nanoparticles in cardiac regenerative medicine, as well as applications for exosome expansion and delivery on a large clinical scale.

Biomimetic nanoparticle technology for cardiovascular disease detection and treatment

Cardiovascular disease (CVD), which encompasses a number of conditions that can affect the heart and blood vessels, presents a major challenge for modern-day healthcare. Nearly one in three people has some form of CVD, with many suffering from multiple or intertwined conditions that can ultimately lead to traumatic events such as a heart attack or stroke. While the knowledge obtained in the past century regarding the cardiovascular system has paved the way for the development of life-prolonging drugs and treatment modalities, CVD remains one of the leading causes of death in developed countries. More recently, researchers have explored the application of nanotechnology to improve upon current clinical paradigms for the management of CVD. Nanoscale delivery systems have many advantages, including the ability to target diseased sites, improve drug bioavailability, and carry various functional payloads. In this review, we cover the different ways in which nanoparticle technology can be applied towards CVD diagnostics and treatments. The development of novel biomimetic platforms with enhanced functionalities is discussed in detail.

Engineered Nanoplatelets for Targeted Delivery of Plasminogen Activators to Reverse Thrombus in Multiple Mouse Thrombosis Models

Rapid cut-off of blood supply in diseases involving thrombosis is a major cause of morbidity and mortality worldwide. However, the current thrombolysis strategies offer limited results due to the therapeutics' short half-lives, low targeting ability, and unexpected bleeding complications. Inspired by the innate roles of platelets in hemostasis and pathological thrombus, platelet membrane-camouflaged polymeric nanoparticles (nanoplatelets) are developed for targeting delivery of the thrombolytic drug, recombinant tissue plasminogen activator (rt-PA), to local thrombus sites. The tailor-designed nanoplatelets efficiently accumulate at the thrombi in pulmonary embolism and mesenteric arterial thrombosis model mice, eliciting a significantly enhanced thrombolysis activity compared to free rt-PA. In addition, the nanoplatelets exhibit improved therapeutic efficacy over free rt-PA in an ischemic stroke model. Analysis of in vivo coagulation indicators suggests the nanoplatelets might possess a low risk of bleeding complications. The hybrid biomimetic nanoplatelets described offer a promising solution to improve the efficacy and reduce the bleeding risk of thrombolytic therapy in a broad spectrum of thrombosis diseases.

Molecular events in MSC exosome mediated cytoprotection in cardiomyocytes

A host of hormonal-metabolic alterations take place following exposure of cardiomyocytes to hypoxia and other noxious stimuli. Here, we demonstrate that exposure of cultured rat cardiomyocytes to lipopolysaccharide (LPS) resulted in upregulation (~1.5 fold) of oxidized low-density lipoprotein receptor-1 (LOX-1). There was also a marked increase in apoptosis 12 hrs after LPS treatment with caspase-3 levels being significantly elevated (~1.3 fold) and a significant increase in LDH release at 24 hrs. Interestingly, there was a ~1.4-fold upregulation of LC-3 expression post-LPS treatment indicating development of autophagy, which probably is a compensatory response to combat cellular injury induced by LPS. Treatment with LPS also reduced the size and morphology of cardiomyocyte spheroids. In an attempt to limit LPS-induced injury, cardiomyocytes were treated with exosomes derived from mesenchymal stromal cells (MSCs). We noted a significant suppression of LOX-1 expression that in turn suppressed apoptosis as well as autophagic response and restored spheroid morphology. Mass spectrophotometric analysis of MSC exosomes revealed a cargo rich in proteins which are involved in pathways negatively modulating cell death and apoptosis while promoting cell survival. This is first report to our knowledge on the initial molecular events in MSC exosome mediated cytoprotection of stressed cardiomyocytes.

Cell therapy trials for heart regeneration - lessons learned and future directions

The effects of cell therapy on heart regeneration in patients with chronic cardiomyopathy have been assessed in several clinical trials. These trials can be categorized as those using noncardiac stem cells, including mesenchymal stem cells, and those using cardiac-committed cells, including KIT⁺ cardiac stem cells, cardiosphere-derived cells, and cardiovascular progenitor cells derived from embryonic stem cells. Although the safety of cell therapies has been consistently reported, their efficacy remains more elusive. Nevertheless, several lessons have been learned that provide useful clues for future studies. This Review summarizes the main outcomes of these studies and draws some perspectives for future cell-based regenerative trials, which are largely based on the primary therapeutic target: remuscularization of chronic myocardial scars by exogenous cells or predominant use of these cells to activate host-associated repair pathways though paracrine signalling. In the first case, the study design should entail delivery of large numbers of cardiac-committed cells, supply of supportive noncardiac cells, and promotion of cell survival and appropriate coupling with endogenous cardiomyocytes. If the primary objective is to harness endogenous repair pathways, then the flexibility of cell type is greater. As the premise is that the transplanted cells need to engraft only transiently, the priority is to optimize their early retention and possibly to switch towards the sole administration of their secretome.

Cells and cell derivatives as drug carriers for targeted delivery

For over a century, researchers have focused on how to optimize drug delivery. Systemic administration means that the drug becomes dilute and has the potential to diffuse to all tissues, which is only until the immune system steps in and rapidly clears it from blood circulation. Drug carriers are the solution for amplifying the intended effect and diminishing side effects. With drug carriers, tissue-specific drug delivery and controlled drug release is possible. Thus far, both synthetic and non-synthetic carriers exist. However, due to the numerous limitations of synthetic carriers, science has begun to concentrate on using live cells and cell-derivatives as drug carriers. The most problematic shortcomings of synthetic carriers are their limited biocompatibility and biodegradability. Most synthetic carriers are cytotoxic or induce immune responses. Moreover, synthetic carriers typically depend on passive diffusion and risk phagocytosis, further reducing their impact. On the other hand, live-cell carriers and their derivatives usually have a targeting mechanism and drug release is controlled, increasing the efficiency with which a drug accumulates and acts on a tissue. Still, both types of carriers face similar problems, including achieving high loading capacity, maintaining drug quality, efficiently accumulating in the target tissue, and minimizing side effects. This review aims to elucidate the advantages and disadvantages of each popular cell or cell-derived carrier and to spotlight novel solutions.

Chemical Engineering of Cell Therapy for Heart Diseases

Cardiovascular disease (CVD) is a major health problem worldwide. Since adult cardiomyocytes irreversibly withdraw from the cell cycle soon after birth, it is hard for cardiac cells to proliferate and regenerate after myocardial injury, such as that caused myocardial infarction (MI). Live cell-based therapies, which we term as first generation of therapeutic strategies, have been widely used for the treatment of many diseases, including CVD. However, cellular approaches have the problems of poor retention of the transplanted cells and the significant entrapment of the cells in the lungs when delivered intravenously. Another big problem is the low storage/shipping stability of live cells, which limits the manufacturability of living cell products. The field of chemical engineering focuses on designing large-scale processes to convert chemicals, raw materials, living cells, microorganisms, and energy into useful forms and products. By definition, chemical engineers conceive and design processes to produce, transform, and transport materials. This matches the direction that cell therapies are heading toward: "produce", from live cells to synthetic artificial cells; "transform", from bare cells to cell/matrix/factor combinations; and "transport". from simple systemic injections to targeted delivery. Thus, we hereby introduce the "chemical engineering of cell therapies" as a concept. In this Account, we summarize our recent efforts to develop chemical engineering approaches to repair injured hearts. To address the limitations of poor cellular retention and integration, the first step was the artificial manipulation of stem cells before injections (we term this the second generation of therapeutic strategies). For example, we took advantage of the natural infarct-targeting ability of platelet membranes by fusing them onto the surface of cardiac stromal/stem cells (CSCs). By doing so, we improved the rate at which they were delivered through the vasculature to sites of MI. In addition to modifying natural CSCs, we described a bioengineering approach that involved the encapsulation of CSCs in a polymeric microneedle patch for myocardium regeneration. The painless microneedle patches were used as an in situ delivery device, which directly transported the loaded CSCs to the MI heart. In addition to low cell retention, there are some other barriers that need to be addressed before further clinical application is viable, including the storage/shipping stability of and the evident safety concerns about live cells. Therefore, we developed the third generation of therapeutic strategies, which utilize cell-free approaches for cardiac cell therapies. Numerous studies have indicated that paracrine mechanisms reasonably explain stem cell based heart repair. By imitating or adapting natural stem cells, as well as their secretions, and using them in conjunction with biocompatible materials, we can simulate the function of natural stem cells while avoiding the complications association with the first and second generation therapeutic options. Additionally, we can develop approaches to capture endogenous stem cells and directly transport them to the infarct site. Using these third generation therapeutic strategies, we can provide unprecedented opportunities for cardiac cell therapies. We hope that our designs will promote the use of chemical engineering approaches to transform, transport, and fabricate cell-free systems as novel cardiac cell therapeutic agents for clinical applications.

microRNA-21-5p dysregulation in exosomes derived from heart failure patients impairs regenerative potential

Exosomes, as functional paracrine units of therapeutic cells, can partially reproduce the reparative properties of their parental cells. The constitution of exosomes, as well as their biological activity, largely depends on the cells that secrete them. We isolated exosomes from explant-derived cardiac stromal cells from patients with heart failure (FEXO) or from normal donor hearts (NEXO) and compared their regenerative activities in vitro and in vivo. Patients in the FEXO group exhibited an impaired ability to promote endothelial tube formation and cardiomyocyte proliferation in vitro. Intramyocardial injection of NEXO resulted in structural and functional improvements in a murine model of acute myocardial infarction. In contrast, FEXO therapy exacerbated cardiac function and left ventricular remodeling. microRNA array and PCR analysis revealed dysregulation of miR-21-5p in FEXO. Restoring miR-21-5p expression rescued FEXO's reparative function, whereas blunting miR-21-5p expression in NEXO diminished its therapeutic benefits. Further mechanistic studies revealed that miR-21-5p augmented Akt kinase activity through the inhibition of phosphatase and tensin homolog. Taken together, the heart failure pathological condition altered the miR cargos of cardiac-derived exosomes and impaired their regenerative activities. miR-21-5p contributes to exosome-mediated heart repair by enhancing angiogenesis and cardiomyocyte survival through the phosphatase and tensin homolog/Akt pathway.

Conductive Hydrogen Sulfide-Releasing Hydrogel Encapsulating ADSCs for Myocardial Infarction Treatment

Hydrogen sulfide (H₂S) exhibits extensive protective actions in cardiovascular systems, such as anti-inflammatory and stimulating angiogenesis, but its therapeutic potential is severely discounted by the short half-life and the poorly controlled releasing behavior. Herein, we developed a macromolecular H₂S prodrug by grafting 2-aminopyridine-5-thiocarboxamide (a small-molecule H₂S donor) on partially oxidized alginate (ALG-CHO) to mimic the slow and continuous release of endogenous H₂S. In addition, tetraaniline (a conductive oligomer) and adipose-derived stem cells (ADSCs) were introduced to form a stem cell-loaded conductive H₂S-releasing hydrogel through the Schiff base reaction between ALG-CHO and gelatin. The hydrogel exhibited adhesive property to ensure a stable anchoring to the wet and beating hearts. After myocardial injection, longer ADSCs retention period and elevated sulfide concentration in rat myocardium were demonstrated, accompanied by upregulation of cardiac-related mRNA (Cx43, α-SMA, and cTnT) and angiogenic factors (VEGFA and Ang-1) and downregulation of inflammatory factors (tumor necrosis factor-α). Echocardiography and histological analysis strongly demonstrated an increase in the ejection fraction value and smaller infarction size, suggesting a remarkable improvement of the cardiac functions of Sprague-Dawley rats. The ADSC-loaded conductive hydrogen sulfide-releasing hydrogel dramatically promoted the therapeutic effects, offering a promising therapeutic strategy for treating myocardial infarction.

Artificially Reprogrammed Macrophages as Tumor-Tropic Immunosuppression-Resistant Biologics to Realize Therapeutics Production and Immune Activation

To engineer patient-derived cells into therapy-purposed biologics is a promising solution to realize personalized treatments. Without using gene-editing technology, a live cell-typed therapeutic is engineered for tumor treatment by artificially reprogramming macrophages with hyaluronic acid-decorated superparamagnetic iron oxide nanoparticles (HIONs). This nanoparticle-assisted cell-reprogramming strategy demonstrates profound advantages, due to the combined contributions from the biological regulation of HIONs and the intrinsic nature of macrophages. Firstly, the reprogrammed macrophages present a substantial improvement in their innate capabilities, such as more effective tumor targeting and more efficient generation of bioactive components (e.g., reactive oxygen species, bioactive cytokines) to suppress tumor growth. Furthermore, this cell therapeutic exhibits cytostatic/proapoptotic effects specific to cancer cells. Secondly, HIONs enable macrophages more resistant to the intratumoral immunosuppressive environment. Thirdly, the macrophages are endowed with a strong ability to prime in situ protumoral M2 macrophages into antitumor M1 phenotype in a paracrine-like manner. Consequently, a synergistic tumor-inhibition effect is achieved. This study shows that engineering nanomaterial-reprogrammed live cells as therapeutic biologics may be a more preferable option to the commonly used approaches where nanomaterials are administrated to induce bioresponse of certain cells in vivo.

Antibody-Armed Platelets for the Regenerative Targeting of Endogenous Stem Cells

Stem cell therapies have shown promise in treating acute and chronic ischemic heart disease. However, current therapies are limited by the low retention and poor integration of injected cells in the injured tissue. Taking advantage of the natural infarct-homing ability of platelets, we engineered CD34 antibody-linked platelets (P-CD34) to capture circulating CD34-positive endogenous stem cells and direct them to the injured heart. In vitro, P-CD34 could bind to damaged aortas and capture endogenous stem cells in whole blood. In a mouse model of acute myocardial infarction, P-CD34 accumulated in the injured heart after intravenous administration, leading to a concentration of endogenous CD34 stem cells in the injured heart for effective heart repair. This represents a new technology for endogenous stem cell therapy.

Design strategies and application progress of therapeutic exosomes

Exosomes have great potential to be drug delivery vehicles due to their natural material transportation properties, intrinsic long-term circulatory capability, and excellent biocompatibility, which are suitable for delivering a variety of chemicals, proteins, nucleic acids, and gene therapeutic agents. However, an effective method of loading specific protein agents into exosomes for absorption by target cells is still lacking. The application potential of exosome is still limited. In this review, we discussed the methods for loading specific treating molecules (proteins, nucleic acids and small chemicals) into exosomes, the design strategies for cell and tissue targeting, and the factors for exosome formation. This review can be used as a reference for further research as well as for the development of therapeutic exosomes.

Platelet-Inspired Nanocells for Targeted Heart Repair After Ischemia/Reperfusion Injury

Cardiovascular disease is the leading cause of mortality worldwide. While reperfusion therapy is vital for patient survival post-heart attack, it also causes further tissue injury, known as myocardial ischemia/reperfusion (I/R) injury in clinical practice. Exploring ways to attenuate I/R injury is of clinical interest for improving post-ischemic recovery. A platelet-inspired nanocell (PINC) that incorporates both prostaglandin E2 (PGE2)-modified platelet membrane and cardiac stromal cell-secreted factors to target the heart after I/R injury is introduced. By taking advantage of the natural infarct-homing ability of platelet membrane and the overexpression of PGE2 receptors (EPs) in the pathological cardiac microenvironment after I/R injury, the PINCs can achieve targeted delivery of therapeutic payload to the injured heart. Furthermore, a synergistic treatment efficacy can be achieved by PINC, which combines the paracrine mechanism of cell therapy with the PGE2/EP receptor signaling that is involved in the repair and regeneration of multiple tissues. In a mouse model of myocardial I/R injury, intravenous injection of PINCs results in augmented cardiac function and mitigated heart remodeling, which is accompanied by the increase in cycling cardiomyocytes, activation of endogenous stem/progenitor cells, and promotion of angiogenesis. This approach represents a promising therapeutic delivery platform for treating I/R injury.

A New Era of Cardiac Cell Therapy: Opportunities and Challenges

Myocardial infarction (MI), caused by coronary heart disease (CHD), remains one of the most common causes of death in the United States. Over the last few decades, scientists have invested considerable resources on the study and development of cell therapies for myocardial regeneration after MI. However, due to a number of limitations, they are not yet readily available for clinical applications. Mounting evidence supports the theory that paracrine products are the main contributors to the regenerative effects attributed to these cell therapies. The next generation of cell-based MI therapies will identify and isolate cell products and derivatives, integrate them with biocompatible materials and technologies, and use them for the regeneration of damaged myocardial tissue. This review discusses the progress made thus far in pursuit of this new generation of cell therapies. Their fundamental regenerative mechanisms, their potential to combine with other therapeutic products, and their role in shaping new clinical approaches for heart tissue engineering, are addressed.

Pretargeting and Bioorthogonal Click Chemistry-Mediated Endogenous Stem Cell Homing for Heart Repair

Stem cell therapy is one of the promising strategies for the treatment of ischemic heart disease. However, the clinical application of stem cells transplantation is limited by low cell engraftment in the infarcted myocardium. Taking advantage of pretargeting and bioorthogonal chemistry, we engineered a pretargeting and bioorthogonal chemistry (PTBC) system to capture endogenous circulating stem cells and target them to the injured heart for effective repair. Two bioorthogonal antibodies were i.v. administrated with a pretargeting interval (48 h). Through bioorthogonal click reaction, the two antibodies are linked in vivo, engaging endogenous stem cells with circulating platelets. As a result, the platelets redirect the stem cells to the injured heart. In vitro and in vivo studies demonstrated that bioorthogonal click reaction was able to induce the conjugation of platelets and endothelial progenitor cells (EPCs) and enhance the binding of EPCs to collagen and injured blood vessels. More importantly, in a mouse model of acute myocardial infarction, the in vivo results of cardiac function, heart morphometry, and immunohistochemistry assessment all confirmed effective heart repair by the PTBC system.

Platelets and their biomimetics for regenerative medicine and cancer therapies

Platelets, circulating blood cells derived from megakaryocytes, play a key role in various physical activities, including coagulation, hemostasis, the body's innate immune response, and cancer metastasis. By taking advantage of their key traits, researchers have developed strategies to exploit platelets and platelet-mimicking nanoassemblies to treat a number of conditions, including wounds, cancers, and bacterial infections. Compared to traditional polymer, lipsosome, and inorganic nanoparticles-based delivery systems, platelets and platelet-mimicking vehicles hold many advantages. Among these are their enhanced circulation time, their large volumes and surface areas for drug loading or conjugation, and their inherent ability to target some diseases. In this review, we will highlight the recent progress made in the development of disease-targeting platelets- and platelet-mimicking-vehicles as therapeutic platforms.

Platelet for drug delivery

Platelets play a vital physiological role in hemostasis, inflammation and tissue regeneration, which are associated with wound healing as well as cancer development and metastasis. These years, a variety of platelet-mediated drug delivery approaches have been developed due to their unique properties, such as quick replenishment and site-specific activation/adhesion. In this Current Opinion, focuses are put on strategies leveraging the physiological functions of platelets for the design of drug delivery systems, including platelet engineering, platelet hitchhiking, membrane coating, synthetic platelet fabrication and platelet-triggered drug release for different applications.

NIPAM-based Microgel Microenvironment Regulates the Therapeutic Function of Cardiac Stromal Cells

To tune the chemical, physical, and mechanical microenvironment for cardiac stromal cells to treat acute myocardial infarction (MI), we prepared a series of thermally responsive microgels with different surface charges (positive, negative, and neutral) and different degrees of hydrophilicity, as well as functional groups (carboxyl, hydroxyl, amino, and methyl). These microgels were used as injectable hydrogels to create an optimized microenvironment for cardiac stromal cells (CSCs). Our results indicated that a hydrophilic and negatively charged microenvironment created from poly( N-isopropylacrylamide- co-itaconic acid) was favorable for maintaining high viability of CSCs, promoting CSC proliferation and facilitating the formation of CSC spheroids. A large number of growth factors, such as vascular endothelial growth factor (VEGF), insulin-like growth factor I (IGF-1), and stromal-derived factor-1 (SDF-1) were released from the spheroids, promoting neonatal rat cardiomyocyte activation and survival. After injecting the poly( N-isopropylacrylamide- co-itaconic acid) microgel into mice, we examined their acute inflammation and T-cell immune reactions. The microgel itself did not elicit obvious immune response. We then injected the same microgel-encapsulated with CSCs into MI mice. The result revealed the treatment-promoted MI heart repair through angiogenesis and inhibition of apoptosis with an improved cell retention rate. This study will open a door for tailoring poly( N-isopropylacrylamide)-based microgel as a delivery vehicle for CSC therapy.

Cardiac cell-integrated microneedle patch for treating myocardial infarction

We engineered a microneedle patch integrated with cardiac stromal cells (MN-CSCs) for therapeutic heart regeneration after acute myocardial infarction (MI). To perform cell-based heart regeneration, cells are currently delivered to the heart via direct muscle injection, intravascular infusion, or transplantation of epicardial patches. The first two approaches suffer from poor cell retention, while epicardial patches integrate slowly with host myocardium. Here, we used polymeric MNs to create "channels" between host myocardium and therapeutic CSCs. These channels allow regenerative factors secreted by CSCs to be released into the injured myocardium to promote heart repair. In the rat MI model study, the application of the MN-CSC patch effectively augmented cardiac functions and enhanced angiomyogenesis. In the porcine MI model study, MN-CSC patch application was nontoxic and resulted in cardiac function protection. The MN system represents an innovative approach delivering therapeutic cells for heart regeneration.

Body builder: from synthetic cells to engineered tissues

It is estimated that 18 Americans die every day waiting for an organ donation. And even if a patient receives the organ that s/he needs, there is still >10% chance that the new organ will not work. The field of tissue engineering and regenerative medicine aims to actively use a patient's own cells, plus biomaterials and factors, to grow specific tissues for replacement or to restore normal functions of that organ, which would eliminate the need for donors and the risk of alloimmune rejection. In this review, we summarized recent advances in fabricating synthetic cells, with a specific focus on their application to cardiac regenerative medicine and tissue engineering. At the end, we pointed to challenges and future directions for the field.

Cell-Like Micromotors

In the past decade, versatile micro- and nanosized machines have emerged as active agents for large-scale detoxification, sensing, microfabrication, and many other promising applications. Micromachines have also been envisioned as the next advancement in dynamic therapy with numerous proof-of-concept studies in drug delivery, microsurgery, and detoxification. However, the practical use of synthetic micromotors in the body requires the development of fully biocompatible designs facilitating micromotor movement in biological fluids of diverse composition and displaying desired functions in specific locations. The combination of the efficient movement of synthetic micromotors with the biological functions of natural cells has resulted in cell-like micromotors with expanded therapeutic and toxin-removing capabilities toward different biological applications. Thus, these biocompatible and biomimetic cell-like micromotors can provide efficient movement in complex biofluids and mimic the functionalities of natural cells. This Account highlights a variety of recent proof-of-concept examples of cell-like micromotors, based on different designs and actuation mechanisms, which perform diverse in vivo tasks. The cell-like micromotors are divided into two groups: (i) cell membrane-coated micromotors, which use natural cell membranes derived from red blood cells, platelets, or a combination of different cells to cloak and functionalize synthetic motors, and (ii) cell-based micromotors, which directly use entire cells such as blood cells, spermatozoa, and bacteria as the micromotor engine. Cell-like micromotors, composed of different cellular components and actuated by different mechanisms, have shown unique advantages for operation in complex biofluids such as blood. Due to the inherent biocompatibility of cell-derived materials, these cell-like micromotors do not provoke an immune response while utilizing useful secondary functions of the blood cells such as strong ability to soak up foreign agents or bind toxins. Additionally, the utilization of autonomously motile cells (e.g., bacteria) allows for built-in chemotactic motion, which eliminates the need for harmful fuels or complex actuation equipment. Furthermore, a broad range of cells, both passive and motile, can be incorporated into micromachine designs constituting a large library of functional components depending on the limits of the desired application. The coupling of cellular and artificial components has led to active biohybrid swimming microsystems with greatly enhanced capabilities and functionalities compared to the individual biological or synthetic components. These characteristics have positioned these cell-like micromotors as promising biomimetic dynamic tools for potential actuation in vivo. Finally, the key challenges and limitations of cell-like micromotors are discussed in the context of expanded future clinical uses and translation to human trials.

Targeted Treatment of Ischemic and Fibrotic Complications of Myocardial Infarction Using a Dual-Delivery Microgel Therapeutic

Myocardial infarction (MI), commonly known as a heart attack, affects millions of people worldwide and results in significant death and disabilities. A major cause of MI is fibrin-rich thrombus formation that occludes the coronary arteries, blocking blood flow to the heart and causing fibrin deposition. In treating MI, re-establishing blood flow is critical. However, ischemia reperfusion (I/R) injury itself can also occur and contributes to cardiac fibrosis. Fibrin-specific poly( N-isopropylacrylamide) nanogels (FSNs) comprised of a core-shell colloidal hydrogel architecture are utilized in this study to design a dual-delivery system that simultaneously addresses the need to (1) re-establish blood flow and (2) inhibit cardiac fibrosis following I/R injury. These therapeutic needs are met by controlling the release of a fibrinolytic protein, tissue plasminogen activator (tPA), and a small molecule cell contractility inhibitor (Y-27632). In vitro, tPA and Y-27632-loaded FSNs rapidly degrade fibrin and decrease cardiac cell stress fiber formation and connective tissue growth factor expression, which are both upregulated in cardiac fibrosis. In vivo, FSNs localize to fibrin in injured heart tissue and, when loaded with tPA and Y-27632, showed significant improvement in left ventricular ejection fraction 2 and 4 weeks post-I/R as well as significantly decreased infarct size, α-smooth muscle actin expression, and connective tissue growth factor expression 4 weeks post-I/R. Together, these data demonstrate the feasibility of this targeted therapeutic strategy to improve cardiac function following MI.

Bioengineered stem cell membrane functionalized nanocarriers for therapeutic targeting of severe hindlimb ischemia

Bioengineering strategies to enhance the natural targeting function of nanocarriers would expand their therapeutic applications. Here, we designed bioengineered stem cell membrane-functionalized nanocarriers (BSMNCs) harboring C-X-C chemokine receptor type 4 (CXCR4) to achieve robust targeting and also to increase their retention time in ischemic tissue. Stem cell membrane coated nanocarrier (SMNCs) or poly (lactic-co-glycolic acid) (PLGA) nanocarriers (PNCs) and BSMNCs were prepared by functionalizing PNCs with human adipose-derived stem cells (hASCs) membranes and hASCs engineered to overexpress CXCR4-receptor, respectively. The functionalization of PNCs with stem cell membranes derived from hASCs significantly enhance the nanocarrier penetration across endothelial cell barrier compare to PNCs. In addition, stem cell membrane functionalization on PNCs also significantly decreased the nanoparticles uptake in J774 (murine) and THP (human) macrophages respectively from 84% to 76%-29% and 24%. Interestingly, BSMNCs showed much higher level of accumulation in ischemic tissue than SMNCs. Systemic retro-orbital injection of BSMNCs loaded with VEGF into mice with hindlimb ischemia resulted substantially enhancement of blood reperfusion, muscle repair, and limb salvage compared to animals treated with SMNCs loaded with similar concentration of VEGF. The reported strategy could be used to create biocompatible and custom-tailored biomimetic nanoparticles with various hybrid functionalities, which may overcome the limitations of current nanoparticle-based therapeutic and imaging platforms.