Z. Ryan Tian

Drug delivery to the spinal cord tagged with nanowire enhances neuroprotective efficacy and functional recovery following trauma to the rat spinal cord

The possibility that drugs attached to innocuous nanowires enhance their delivery within the central nervous system (CNS) and thereby increase their therapeutic efficacy was examined in a rat model of spinal cord injury (SCI). Three compounds—AP173 (SCI‐1), AP713 (SCI‐2), and AP364 (SCI‐5) (Acure Pharma, Uppsala, Sweden)—were tagged with TiO2‐based nanowires using standard procedure. Normal compounds were used for comparison. SCI was produced by making a longitudinal incision into the right dorsal horn of the T10–T11 segments under Equithesin anesthesia. The compounds, either alone or tagged with nanowires, were applied topically within 5 to 10 min after SCI. In these rats, behavioral outcome, blood–spinal cord barrier (BSCB) permeability, edema formation, and cell injury were examined at 5 h after injury. Topical application of normal compounds in high quantity (10 μg in 20 μL) attenuated behavioral dysfunction (3 h after trauma), edema formation, and cell injury, as well as reducing BSCB permeability to Evans blue albumin and 131I. These beneficial effects are most pronounced with AP713 (SCI‐2) treatment. Interestingly, when these compounds were administered in identical conditions after tagging with nanowires, their beneficial effects on functional recovery and spinal cord pathology were further enhanced. However, topical administration of nanowires alone did not influence trauma‐induced spinal cord pathology or motor functions. Taken together, our results, probably for the first time, indicate that drug delivery and therapeutic efficacy are enhanced when the compounds are administered with nanowires.

Nanowired Drug Delivery to Enhance Neuroprotection in Spinal Cord Injury

Spinal cord injury (SCI) is a serious clinical situation for which no suitable drug therapy exists. SCI often results in paraplegia or quadriplegia and, apart from the personal trauma leads to huge costs to society for rehabilitation or day-to-day life support. Sensory motor dysfunction following SCI is mainly a consequence of the slowly progressing cord pathology after primary injury that worsens over tine. Thus, almost all sensory and motor nerve control and pathways passing through spinal cord and reflexes are compromised in SCI patients. As a result their peripheral nervous system, autonomic nervous function and central nervous system regulations are adversely affected. Experiments carried out in our laboratory show that various therapeutic agents, if given within 10 to 30 minutes after primary SCI could correct morphological changes to a certain extent. In these rat models of SCI reduction in cord pathology, e.g., bloodspinal cord barrier (BSCB) breakdown, edema formation and cell injury by the neuroprotective agents that also limited sensory motor dysfunction and improved functional behavior. However, these drugs if given beyond 30 minutes after SCI showed a markedly reduced neuroprotective efficacy. Thus, new strategies are needed to enhance neuroprotection in SCI to prevent structural and functional changes over longer periods of time. To that end our laboratory has initiated a series of investigations in which nanowired delivery of various neurotherapeutic agents are applied after different time periods of SCI, that resulted in a much better outcome than with the parent compounds under identical conditions. The superior neuroprotective activity of nanowired compound delivery could be due to a reduced metabolism of active compounds in the central nervous system (CNS) or by sustained release of the drug for longer times. In addition, nanowired drugs may penetrate the CNS faster and could reach widespread areas once entering the spinal cord. Thus, nanowired drug delivery to treat SCI may have potential therapeutic value. These aspects of nanowired drug delivery to enhance neuroprotection in SCI are discussed in this review based on our own investigations.

Nanowired-Drug Delivery Enhances Neuroprotective Efficacy of Compounds and Reduces Spinal Cord Edema Formation and Improves Functional Outcome Following Spinal Cord Injury in the Rat

The possibility that drugs attached to nanowires enhance their therapeutic efficacy was examined in a rat model of spinal cord injury (SCI). Three Acure compounds AP-173, AP-713 and AP-364 were tagged with TiO(2)-based nanowires (50-60 nm) and applied over the traumatized cord either 5 or 60 min after SCI in rats produced by a longitudinal incision into the right dorsal horn of the T10-11 segments under equithesin anaesthesia. Normal compounds were used for comparison. After 5 h SCI, behavioral outcome, blood-spinal cord barrier (BSCB) permeability, edema formation and cell injury were examined. Topical application of nanowired compound AP-713 (10 microg in 20 microL) when applied either 5 or 60 min after injury markedly attenuated behavioral dysfunction at 2-3 h after SCI and reduces BSCB disruption, edema formation and cord pathology at 5 h compared to other compounds. Whereas normal compounds applied at 5 min after injury (but not after 60 min) had some significant but less beneficial effects compared to their nanowired combinations. On the other hand, nanowires alone did not influence spinal cord pathology or motor function after SCI. Taken together, our results indicate that the nanowired-drug-delivery enhances the neuroprotective efficacy of drugs in SCI and reduces functional outcome compared to normal compounds even applied at a later stage following trauma, not reported earlier.

Design and hierarchical synthesis of branched heteromicrostructures

Smart heteromicrostructures of a new kind, composed of SiO2 microspheres and ZnO branches, have been prepared hierarchically for the first time. Such heteromicrostructures have been characterized by means of x-ray diffraction and field emission scanning electron microscopy. Suggesting a possible formation process has been tackled. This type of smart branched heteromaterial is expected to have applications in fields of nanomedicine such as clearing clogged arteries, breaking aggregated amyloids and delivering drugs.

Nanowired Drug Delivery Across the Blood-Brain Barrier in Central Nervous System Injury and Repair

The blood-brain barrier (BBB) is a physiological regulator of transport of essential items from blood to brain for the maintenance of homeostasis of the central nervous system (CNS) within narrow limits. The BBB is also responsible for export of harmful or metabolic products from brain to blood to keep the CNS fluid microenvironment healthy. However, noxious insults to the brain caused by trauma, ischemia or environmental/chemical toxins alter the BBB function to small as well as large molecules e.g., proteins. When proteins enter the CNS fluid microenvironment, development of brain edema occurs due to altered osmotic balance between blood and brain. On the other hand, almost all neurodegenerative diseases and traumatic insults to the CNS and subsequent BBB dysfunction lead to edema formation and cell injury. To treat these brain disorders suitable drug therapy reaching their brain targets is needed. However, due to edema formation or only a focal disruption of the BBB e.g., around brain tumors, many drugs are unable to reach their CNS targets in sufficient quantity. This results in poor therapeutic outcome. Thus, new technology such as nanodelivery is needed for drugs to reach their CNS targets and be effective. In this review, use of nanowires as a possible novel tool to enhance drug delivery into the CNS in various disease models is discussed based on our investigations. These data show that nanowired delivery of drugs may have superior neuroprotective ability to treat several CNS diseases effectively indicating their role in future therapeutic strategies.

Nanowired Drug Delivery of Antioxidant Compound H-290/51 Enhances Neuroprotection in Hyperthermia-Induced Neurotoxicity

Nanoparticles from the environment or through industrial sources can induce profound alterations in human health, often leading to brain dysfunction. However, it is still unclear whether nanoparticle intoxication could also alter the physiological or pathological responses of additional brain injury, stress response or disease processes. Military personals engaged in combat or peacekeeping operations are often exposed to nanoparticles from various environmental sources, e.g., Ag, Cu, Si, C, Al. In addition, these military personals are often exposed to high environmental heat, or gun and missle explosion injury leading to head or spinal trauma. Thus it is likely that additional CNS injury or stress-induced pathophysiological processes are influenced by nanoparticle intoxication. In this situation, when a combination of nanoparticles and central nervous system (CNS) injury or stress exist together, drug therapy needed to correct these anomalies may not work as effectively as in normal situation. Previous studies from our laboratory show that nanoparticle-intoxicated animals when subjected to hyperthermia resulted in exacerbation of brain pathology. In these animals, antioxidant compounds, e.g., H-290/51 that inhibits free radical formation and induces marked neuroprotection in normal rats after heat stress, failed to protect brain damage when a combination of nanoparticles and heat exposure was used. However, nanowired H-290/51 resulted in better neuroprotection in nanoparticles intoxicated animals after heat stress. Interestingly, high doses of the normal compound induced some neuroprotection in these nanoparticle-treated, heat-stressed rats. These observations suggest that a combination of nanoparticles and heat stress is dangerous and in such situations modification of drug dosage is needed to achieve comparable neuroprotection. In this review possible mechanisms of nanoparticle-induced exacerbation of heat induced neurotoxicity and brain protection achieved by nanowired drug delivery is discussed that is largely based on our own investigations.

Development of in vivo drug-induced neurotoxicity models

Introduction: Neurotoxicity caused by diverse psychostimulant drugs, for example, methamphetamine, 3,4-methylenedioxy-methamphetamine, cocaine or morphine is a cause of concern to human populations especially the young generation across the world. These recreational drugs affect brain function severely leading to addiction and brain pathology. Use of psychostimulants may induce breakdown of the blood–brain barrier to serum proteins resulting in adverse brain microenvironment, edema cell injury or eventually neuronal death. Thus, there is an urgent need to find out detailed mechanisms of psychostimulants-induced neurotoxicity in vivo models for suitable therapeutic strategies to induce neuroprotection and also to help de-addiction in clinical situations. Areas covered: In this review, psychostimulants drugs-induced neurotoxicity is discussed in view of recent literature and the financial burden it may pose on our society due to rehabilitation and de-addiction. Furthermore, experimental evidences of drug-induced neuroprotection are also discussed. Expert opinion: Use of in vivo models of neurotoxicity caused by psychostimulants is discussed based on author’s own research and to find suitable drugs that could induce neuroprotection including nanodelivery. Furthermore, novel therapeutic agents for de-addiction and reducing neurotoxicity following psychostimulants administration are presented.

Synthesis of Biocompatible Titanate Nanofibers for Effective Delivery of Neuroprotective Agents

Nanoscience provides us with new opportunities to develop nanotechnologies for treating, in particular, central nervous system disorders such as Alzheimer disease and multiple sclerosis. From a methodological point of view, it is challenging to deliver drugs effectively across the blood-brain barrier and blood-cerebrospinal fluid barrier. Our 10-year data and reports from both in vivo and in vitro studies, however, have consistently proved that therapeutic drugs of different types can be generally loaded in/on the nanocarriers for targeted and programmable deliveries to the central nervous system with a high degree of efficacy. This chapter presents a protocol for the synthesis of biocompatible titanate nanofibers as low-cost drug delivery cargos. In addition, a procedure for loading the neuroprotective agent Cerebrolysin onto the nanofibers is briefly described. Finally, experimental observations on the use of nanodrug delivery for superior neuroprotective effects of Cerebrolysin in traumatic brain injury are given as a proof of concept as compared to normal drug alone.

Histaminergic Receptors Modulate Spinal Cord Injury-Induced Neuronal Nitric Oxide Synthase Upregulation and Cord Pathology: New Roles of Nanowired Drug Delivery for Neuroprotection

The possibility that histamine influences the spinal cord pathophysiology following trauma through specific receptor-mediated upregulation of neuronal nitric oxide synthase (nNOS) was examined in a rat model. A focal spinal cord injury (SCI) was inflicted by a longitudinal incision into the right dorsal horn of the T10-11 segments. The animals were allowed to survive 5h. The SCI significantly induced breakdown of the blood-spinal cord barrier to protein tracers, reduced the spinal cord blood flow at 5h, and increased the edema formation and massive upregulation of nNOS expression. Pretreatment with histamine H1 receptor antagonist mepyramine (1mg, 5mg, and 10mg/kg, i.p., 30min before injury) failed to attenuate nNOS expression and spinal cord pathology following SCI. On the other hand, blockade of histamine H2 receptors with cimetidine or ranitidine (1mg, 5mg, or 10mg/kg) significantly reduced these early pathophysiological events and attenuated nNOS expression in a dose-dependent manner. Interestingly, TiO2-naowire delivery of cimetidine or ranitidine (5mg doses) exerted superior neuroprotective effects on SCI-induced nNOS expression and cord pathology. It appears that effects of ranitidine were far superior than cimetidine at identical doses in SCI. On the other hand, pretreatment with histamine H3 receptor agonist α-methylhistamine (1mg, 2mg, or 5mg/kg, i.p.) that inhibits histamine synthesis and release in the central nervous system thwarted the spinal cord pathophysiology and nNOS expression when used in lower doses. Interestingly, histamine H3 receptor antagonist thioperamide (1mg, 2mg, or 5mg/kg, i.p.) exacerbated nNOS expression and cord pathology after SCI. These novel observations suggest that blockade of histamine H2 receptors or stimulation of histamine H3 receptors attenuates nNOS expression and induces neuroprotection in SCI. Taken together, our results are the first to demonstrate that histamine-induced pathophysiology of SCI is mediated via nNOS expression involving specific histamine receptors.

Sleep Deprivation Induced Blood-Brain Barrier Breakdown and Brain Pathology. Neuroprotective Effects of TiO 2 -Nanowired Delivery of Cerebrolysin and Ondansetron

Military personnel are often subjected to sleep deprivation (SD) for long hours during combat or peacekeeping operations across the Globe. Recent reports suggests that sound sleep for less than 4 h results in confusion, simple task calculations, and affects decision making. However, in military life SD of 12–72 h is quite common. It appears that longer duration of SD is related to brain dysfunction. Model experiments carried out in our laboratory show that 12–72 h of SD in rats results in progressive breakdown of the blood-brain barrier (BBB) to proteins and induce brain edema formation. Selective neuronal, glial cell and axonal injuries also occurred in SD that is progressive in nature. Interestingly, the magnitude and intensity of SD depends on environmental temperature and cardiovascular health of the animals. Thus, SD at 34 °C induces 2- to 4- fold brain damage, BBB breakdown and edema formation in rats as compared to identical SD at room temperature (21 ± 1 °C). Also hypertensive rats when subjected to identical SD showed greater degree of brain pathology as compared to normotensive animals. Treatment with a multimodal drug Cerebrolysin that is a balanced composition of several neurotrophic factors and active peptide fragments significantly reduced the brain pathology in healthy animals at room temperature. However, TiO2-nanowired delivery of cerebrolysin is needed to attenuate SD induced brain pathology of normotensive rats at hot environment or hypertensive animals at room temperature. These observations suggest that nanodrug delivery in SD is needed to induce neuroprotection at hot environment or in hypertensive animals, not reported earlier.