Synthetic Platelets Research Articles

Synthetic platelets: can bioengineering realize in few years what evolution made in over 200 million years?

Synthetic platelets: can bioengineering realize in few years what evolution made in over 200 million years?

Topical Synthetic Platelets Loaded With Gentamicin Decrease Bacteria in Deep Partial-Thickness Burns

IntroductionProlonged inflammation and infection in burns may cause inadequate healing. Platelet granules contain anti-inflammatory mediators that impact wound healing. Synthetic platelets (SPs) avoid portability and storage difficulties of natural platelets and can be loaded with bioactive agents. We evaluated wound healing outcomes in deep partial-thickness (DPT) burns treated topically with SP loaded with antibiotics. Materials and methodsThirty DPT burns were created on the dorsum of two Red Duroc hybrid pigs. Six wounds were randomized into five groups: SP alone, SP loaded with gentamicin vesicles, SP with gentamicin mixture, vehicle control (saline), or dry gauze. Wounds were assessed from postburn days 3-90. Primary outcome was re-epithelialization percentage at postburn day 28. Secondary outcomes included wound contraction percentage, superficial blood flow relative to normal skin controls, and bacterial load score. ResultsResults showed that re-epithelialization with the standard of care (SOC) was 98%, SP alone measured 100%, SP loaded with gentamicin vesicles was 100%, and SP with gentamicin mixture was 100%. Wound contraction was 5.7% in the SOC and was ∼10% in both the SP loaded with gentamicin vesicles and SP with gentamicin mixture groups. Superficial blood flow in the SOC was 102.5%, SP alone was 170%, the SP loaded was 155%, and gentamicin mixture 162.5%. Bacterial load score in the SOC was 2.2/5.0 and was significantly less at 0.8/5.0 in SP loaded with gentamicin vesicles (P > 0.05). SP and gentamicin mixture scored 2.7 and 2.3/5.0. ConclusionsTopical SP treatment did not significantly improve outcomes. However, SP loaded with gentamicin-infused vesicles decreased bacterial load.

Haemostatic functions of novel synthetic platelets.

Haemostatic functions of novel synthetic platelets.

Synthetic blood and blood products for combat casualty care and beyond.

Synthetic biology adopts an engineering design approach to create innovative treatments that are reliable, scalable, and customizable to individual patients. Interest in substitutes for allogenic blood components, primarily red blood cells and platelets, increased in the 1980s because of concerns over infectious disease transmission. However, only now, with emerging synthetic approaches, are such substitutes showing genuine promise. Affordable alternatives to donated blood would be of enormous benefit worldwide. Several approaches to replacing the oxygen-carrying function of red cells are under advanced investigation. Hemoglobin-based oxygen carriers incorporate modifications to reduce the renal toxicity and nitric oxide scavenging of free hemoglobin. While use of earlier-generation hemoglobin-based oxygen carriers may be limited to circumstances in which blood transfusion is not an option, recent advances in chemical modification of hemoglobin may eventually overcome such problems. Another approach encases hemoglobin molecules in biocompatible synthetic nanoparticles. An alternative is the ex vivo production of red cells in bioreactors, with or without genetic manipulation, that offers the potential of a universal donor product. Various strategies to manufacture synthetic platelets are also underway, ranging from simple phospholipid liposomes encapsulating adenosine diphosphate and decorated with fibrinogen fragments, to more complex capsules with multiple receptor peptide sequences. Ex vivo production of platelets in bioreactors is also possible including, for example, platelets derived from induced pluripotent stem cells that are differentiated into a megakaryocytic lineage. Prior to clinical use, trials assessing synthetic blood components must evaluate meaningful safety and effectiveness outcomes in relatively large numbers of critically ill patients. Overcoming these challenges may be as much a hurdle as product design. This article reviews the state of the science of the synthetic biology approach to developing blood component substitutes.

Hemostatic strategies for uncontrolled bleeding: A comprehensive update.

Uncontrolled bleeding remains the leading cause of morbidity and mortality across the entire macrocosm. It refers to excessive loss of blood that occurs inside of body, due to unsuccessful platelet plug formation at the injury site. It is not only limited to the battlefield, but remains the second leading cause of death amongst the civilians, as a result of traumatic injury. Startlingly, there are no effective treatments currently available, to cater the issue of internal bleeding, even though early intervention is of utmost significance in minimizing the mortality rates associated with it. The fatal issue of uncontrolled bleeding is ineffectively being dealt with the use of pressure dressings, tourniquet, and surgical procedures. This is not a practical approach in combat arenas or in emergency situations, where the traumatic injury inflicted is deep inside the body, and cannot be addressed externally, by the application of topical dressings. This review focuses on the traditional hemostatic agents that are used to augment the process of hemostasis, such as mineral zeolites, chitosan based products, biologically active agents, anti-fibrinolytics, absorbable agents, and albumin and glutaraldehyde, as well as the micro- and nano-based hemostatic agents such as synthocytes, thromboerythrocytes, thrombosomes, and the synthetic platelets.

Numerical study of the effect of pressure amplitude and frequency on secondary acoustic radiation force between two polystyrene particles in water

Poly(N-isopropylacrylamide) microgels emulate the behavior of natural platelets, promoting wound healing. Our previous studies suggested that ultrasound stimulation of these synthetic platelets further enhances wound healing, by increasing particle displacement and deformation. It is necessary to understand and model the interaction between ultrasound and these particles. We hypothesize that the acoustic radiation force may play a role. Two types of radiation force are considered: a primary radiation force caused by the external acoustic field, and a secondary radiation force resulting from scattering between particles. We present a parametric numerical study of the interaction between polystyrene beads (similar to the synthetic platelets) and an acoustic field, to investigate the effect of magnitude, frequency and bandwidth of excitation field on particle response. This is done via the numerical modeling of the primary and secondary radiation forces using 2-D and 3-D FEM. The 3-D simulations capture the re-scattering effects between the particles. One particle is placed at the origin of the coordinate system (scatterer) and a second particle (probe) is placed in the nodal and anti-nodal pressure planes. The numerical results show a good agreement with the governing theoretical equations proposed by Silva and Bruus, suggesting the relevance of the radiation force hypothesis.

Synthetic Platelets for Treatment of Traumatic Hemorrhage and Thrombocytopenia

Platelets are primarily responsible for staunching bleeding by forming a 'platelet plug' and further amplifying thrombin generation on its surface to facilitate fibrin formation, leading to hemostatic clot formation at the site of vascular breach. Therefore, platelet transfusions are clinically used to mitigate bleeding risks in thrombocytopenia (prophylactic transfusion) and to mitigate hemorrhage in traumatic injuries (emergency transfusion). Currently these transfusions utilize donor-derived platelets, stored at 20-24oC with gentle agitation. In this condition, platelets have high risk of bacterial contamination and very short shelf-life (~ 5 days), which severely limit their logistical availability and use. Several parallel strategies are currently undergoing research to address these issues, including platelet storage at reduced temperatures (chilled or freeze-dried), pathogen reduction technologies and bioreactor-based in vitro platelet production from precursor cells. An alternative (and complimentary) approach that is the focus of our research is the engineering of I.V.-administrable synthetic hemostat nanoparticles that functionally mimic platelet's clotting mechanisms. These 'synthetic platelet' nanoparticle systems can be manufactured at large scale, sterilized without compromising functions and stored for long periods of time (6-9 months), thereby allowing significant logistical advantages in transfusion applications. Here we present in vitro and in vivo evaluation of such technology. For these studies, the 'synthetic platelet' nanoparticles were manufactured by decorating liposomes with a combination of VWF-binding, collagen-binding and fibrinogen-mimetic peptides, for integrative mimicry of platelet's hemostasis-relevant adhesive and aggregatory mechanisms. The nanoparticles were stored at room temperature in aqueous suspension as well as lyophilized powder, and particle stability was assessed over 6-9 months by dynamic light scattering (DLS). The nanoparticles were also exposed to E-beam sterilization, and particle stability as well platelet-mimetic bioactivity was assessed by DLS, aggregometry, microfluidics and rotational thromboelastometry (ROTEM). The systemic safety and targeted hemostatic efficacy of I.V.-administered nanoparticles were evaluated in mouse model of thrombocytopenia, and in mouse, rat and pig models of traumatic hemorrhage. DLS and electron microscopy confirmed that the synthetic platelet nanoparticles have a size of 150-200 nm diameter, and they remain stable over 6-9 months in storage. Microfluidic studies showed that these nanoparticles could rapidly adhere to 'vWF + collagen'-coated surfaces and enhance the recruitment and aggregation of active platelets on these surfaces. Aggregometry studies showed that the nanoparticles did not affect resting platelets but enhanced aggregation of ADP- or collagen-activated platelets (i.e. no thrombotic risk towards resting platelets). Flow cytometry studies confirmed this specificity of nanoparticle binding to active platelets. ROTEM studies showed that the 'synthetic platelet' nanoparticles significantly improved clot kinetics and firmness. In vivo, in all animal models, the nanoparticles showed no systemic pro-thrombotic effects, as assessed by hemodynamics as well as organ histology. In thrombocytopenic mice, prophylactically administered 'synthetic platelet' nanoparticles dose-dependently reduced tail bleeding time. In mouse, rat and pig trauma models, post-injury administration of 'synthetic platelet' nanoparticles reduced blood loss, stabilized blood pressure, delayed hypotension and thereby significantly improved survival. The nanoparticles could be further utilized as a platform for targeted presentation of phosphatidylserine (PS) to augment thrombin generation, or targeted delivery of tranexamic acid (TXA) for anti-fibrinolytic effect or delivery of inorganic polyphosphate (PolyP) to augment clot stability. These studies not only establish the potential of these nanoparticles as a platelet surrogate for transfusion applications, but also demonstrate their utilization as a platform for modular augmentation of various hemostatic outputs in prophylactic and emergency applications. Figure Disclosures Sen Gupta: Haima Therapeutics LLC: Equity Ownership.

Intravenous administration of synthetic platelets (SynthoPlate) in a mouse liver injury model of uncontrolled hemorrhage improves hemostasis.

Clinical resuscitative treatment of traumatic hemorrhage involves transfusion of RBC, platelets and plasma in controlled ratios. However, use of such blood components, especially platelets, present many challenges including availability, portability, contamination risks, and short shelf-life, which limit the use of platelet transfusions outside of large trauma centers such as remote civilian hospitals and austere prehospital settings. This has prompted significant research in platelet substitutes that may resolve the above issues while providing platelet-mimetic hemostatic action. In this framework, we have developed a synthetic platelet surrogate, SynthoPlate, by integrative decoration of platelet function mimetic peptides on a biocompatible lipid nanovesicle platform. We have previously demonstrated hemostatic capability of SynthoPlate in correcting tail-bleeding time in thrombocytopenic mice. Building on this, we hypothesized that SynthoPlate transfusion would decrease bleeding in a murine model of acute hemorrhagic shock. A validated model of uncontrolled intraperitoneal hemorrhage, via liver laceration was used to induce hemorrhagic shock in mice. SynthoPlate, control (unmodified) particles, and normal saline were administered as pretreatment and recue infusions to mice undergoing liver laceration and evaluated for hemostatic benefit by determining differences in blood loss and monitoring real-time hemodynamic data. Pretreatment SynthoPlate transfusion resulted in significant reduction of blood loss following hemorrhage, compared with control particles or normal saline treatment (0.86 ± 0.16 g control particles [CP] vs. 0.84 ± 0.13 g normal saline [NS] vs. 0.68 ± 0.09 g SynthoPlate, p < 0.005). SynthoPlate transfused mice demonstrated improved hemodynamics taking significantly longer to develop post-injury hypotension (168.3 ± 106.6 seconds CP vs. 137 ± 58 seconds NS vs. 546.7 ± 329.8 seconds SynthoPlate, p < 0.05). SynthoPlate infusion following liver laceration, that is, rescue transfusion, also resulted in a significant decrease in blood loss (0.89 ± 0.17 g CP vs. 0.92 ± 0.19 g NS vs. 0.69 ± 0.18 g SynthoPlate, p < 0.05). Transfusion of SynthoPlate particles reduces blood loss in a murine model of liver injury, and SynthoPlates may represent a viable transfusion product for the mitigation of blood loss in acute, severe hemorrhagic shock.

Platelet-mimetic strategies for modulating the wound environment and inflammatory responses.

Platelets closely interface with the immune system to fight pathogens, target wound sites, and regulate tissue repair. Natural platelet levels within the body can be depleted for a variety of reasons, including excessive bleeding following traumatic injury, or diseases such as cancer and bacterial or viral infections. Platelet transfusions are commonly used to improve platelet count and hemostatic function in these cases, but transfusions can be complicated by the contamination risks and short storage life of donated platelets. Lyophilized platelets that can be freeze-dried and stored for longer periods of time and synthetic platelet-mimetic technologies that can enhance or replace the functions of natural platelets, while minimizing adverse immune responses have been explored as alternatives to transfusion. Synthetic platelets typically comprise nanoparticles surface-decorated with peptides or ligands to recreate specific biological characteristics of platelets, including targeting of wound and disease sites and facilitating platelet aggregation. Recent efforts in synthetic platelet design have additionally focused on matching platelet shape and mechanics to recreate the marginalization and clot contraction capabilities of natural platelets. The ability to specifically tune the properties of synthetic platelet-mimetic materials has shown utility in a variety of applications including hemostasis, drug delivery, and targeted delivery of cancer therapeutics.

The Clot Thickens…

Ultra-deformable synthetic platelets stop bleeding in minutes.

The Relationship of Normal Hepatic Synthetic Function and Platelets With Advanced Fibrosis or Cirrhosis

The Relationship of Normal Hepatic Synthetic Function and Platelets With Advanced Fibrosis or Cirrhosis

Tuning Ligand Density on Intravenous Hemostatic Nanoparticles Dramatically Increases Survival Following Blunt Trauma

Targeted nanoparticles are being pursued for a range of medical applications. Here we utilized targeted nanoparticles (synthetic platelets) to halt bleeding in acute trauma. One of the major questions that arises in the field is the role of surface ligand density in targeted nanoparticles' performance. We developed intravenous hemostatic nanoparticles (GRGDS-NP1) and previously demonstrated their ability to reduce bleeding following femoral artery injury and increase survival after lethal liver trauma in the rat. These nanoparticles are made from block copolymers, poly(lactic-co-glycolic acid)-b-poly L-lysine-b-poly(ethylene glycol). Surface-conjugated targeting ligand density can be tightly controlled with this system, and here we investigated the effect of varying density on hemostasis and biodistribution. We increased the targeting peptide (GRGDS) concentration 100-fold (GRGDS-NP100) and undertook an in vitro dose-response study using rotational thromboelastometry, finding that GRGDS-NP100 hemostatic nanoparticles were efficacious at doses at least 10 times lower than the GRGDS-NP1. These results were recapitulated in vivo, demonstrating efficacy at eight-fold lower concentration after lethal liver trauma. 1 h survival increased to 92% compared with a scrambled peptide control, 45% (OR = 14.4, 95% CI = [1.36, 143]), a saline control, 47% (OR = 13.5, 95% CI = [1.42, 125]), and GRGDS-NP1, 80% (OR = 1.30, n.s.). This work demonstrates the impact of changing synthetic platelet ligand density on hemostasis and lays the foundation for methods to determine optimal ligand concentration parameters.

BIOBOARD

INDIA – Zinc Treatment for Infections in Children. JAPAN – Japan Pharma Portfolio Finds Renewed Strength through Record Growth in 2012. JAPAN – Joint Development of a Novel Lyophilized Dual Chamber Prefillable Syringe System. JAPAN – A Genetic Alternative to Fertilizer. SINGAPORE – Made-in-Singapore H5N1 Bird Flu Diagnostic Kit - Detects All Known Strains of H5N1 Virus with a Single Test. THAILAND – KEEEN, Thai Bioremediation Product, Awarded Gold Medal for "Bioremediation Agent developed to Greenovation Product". EUROPE – MorphoSys Antibody Reaches Major Milestone in Collaboration with Roche. EUROPE – New Technique to Predict Heart Attacks. USA – FEI Launches 'Living Lab' for Structural Biology Research at NIH. USA – Synthetic Platelets Built to Treat Bleeding. USA – Software Scans Tongue for Signs of Disease. USA – US Legislation Will Ensure Tighter Checks on Foreign Drug Factories.

Platelet mimetic particles for targeting thrombi in flowing blood.

Platelets are a paradigm for a drug carrier in blood owing to their unique physical and biochemical properties. Here, we report the development of synthetic particles that mimic several physical features and important functional properties of platelets. These synthetic platelets have therapeutic and diagnostic applications for platelet associated disorders.

Intravenous Hemostat: Nanotechnology to Halt Bleeding

Blood loss is the major cause of death in both civilian and battlefield traumas. Methods to staunch bleeding include pressure dressings and absorbent materials. For example, QuikClot effectively halts bleeding by absorbing large quantities of fluid and concentrating platelets to augment clotting, but these treatments are limited to compressible and exposed wounds. An ideal treatment would halt bleeding only at the injury site, be stable at room temperature, be administered easily, and work effectively for internal injuries. We have developed synthetic platelets based on Arg-Gly-Asp functionalized nanoparticles, which halve bleeding time after intravenous administration in a rat model of major trauma. The effects of these synthetic platelets surpass other treatments, including recombinant factor VIIa, which is used clinically for uncontrolled bleeding. Synthetic platelets were cleared within 24 hours at a dose of 20 mg/ml, and no complications were seen out to 7 days after infusion, the longest time point studied. These synthetic platelets may be useful for early intervention in trauma and demonstrate the role that nanotechnology can have in addressing unmet medical needs.

Nanoparticles and Nanolayers In Commercial Applications

This paper presents particulate and layered materials used in industry with at least one dimension under 500 nm. The objective is to bring to the attention of researchers areas of investigation where new properties and phenomena may manifest. The most relevant materials are natural and synthetic platelets and spherical and coated silica particles.

Silicate Clay Platelet Dispersion in a Polymer Matrix

The use of dynamic light scattering to monitor the dispersion of clay platelets in a polymer matrix is described. The dispersed clay/polymer composite was prepared by joining surfactant monomers to synthetic hectorite clay platelets by a cationic exchange reaction and subsequently polymerizing with acrylamide. Dispersion of the organically modified clay in aqueous solution was facilitated by preparing a clay surfactant precursor suspension with a surfactant concentration significantly above the clay cation exchange capacity. At lower surfactant concentrations the clay does not disperse but instead forms large polydisperse aggregates unsuitable for making homogeneous composites. The presence of these aggregates could not be found in an x-ray powder diffraction scan but were clearly detected using dynamic light scattering.