The particle size of drug nanocarriers dictates the fate of neurons; critical points in neurological therapeutics

Nanocarrier design–function relationship: The prodigious role of properties in regulating biocompatibility for drug delivery applications

The concept of drug delivery systems as a magic bullet for the delivery of bioactive compounds has emerged as a promising approach in the treatment of different diseases with significant advantages over the limitations of traditional methods. While nanocarrier-based drug delivery systems are the main advocates of drug uptake because they offer several advantages including reduced non-specific biodistribution, improved accumulation, and enhanced therapeutic efficiency; their safety and biocompatibility within cellular/tissue systems are therefore important for achieving the desired effect. The underlying power of "design-interplay chemistry" in modulating the properties and biocompatibility at the nanoscale level will direct the interaction with their immediate surrounding. Apart from improving the existing nanoparticle physicochemical properties, the balancing of the hosts' blood components interaction holds the prospect of conferring newer functions altogether. So far, this concept has been remarkable in achieving many fascinating feats in addressing many challenges in nanomedicine such as immune responses, inflammation, biospecific targeting and treatment, and so on. This review, therefore, provides a diverse account of the recent advances in the fabrication of biocompatible nano-drug delivery platforms for chemotherapeutic applications, as well as combination therapy, theragnostic, and other diseases that are of interest to scientists in the pharmaceutical industries. Thus, careful consideration of the "property of choice" would be an ideal way to realize specific functions from a set of delivery platforms. Looking ahead, there is an enormous prospect for nanoparticle properties in regulating biocompatibility.

The Twofold Role of Osteogenic Small Molecules in Parkinson's Disease Therapeutics: Crosstalk of Osteogenesis and Neurogenesis

Deemed one of the most problematic neurodegenerative diseases in the elderly population, Parkinson's disease remains incurable to date. Ongoing diagnostic studies, however, have revealed that a large number of small molecule drugs that trigger the BMP2-Smad signaling pathway with an osteogenic nature may be effective in Parkinson's disease treatment. Although BMP2 and Smad1, 3, and 5 biomolecules promote neurite outgrowth and neuroprotection in dopaminergic cells as well, small molecules are quicker at crossing the BBB and reaching the damaged dopaminergic neurons located in the substantia nigra due to a molecular weight less than 500 Da. It is worth noting that osteogenic small molecules that inhibit Smurf1 phosphorylation do not offer therapeutic opportunities for Parkinson's disease; whereas, osteogenic small molecules that trigger Smad1, 3, and 5 phosphorylation may have strong therapeutic implications in Parkinson's disease by increasing the survival rate of dopaminergic cells and neuritogenesis. Notably, from a different perspective, it might be said that osteogenic small molecules can possibly put forth therapeutic options for Parkinson's disease by improving neuritogenesis and cell survival.

Fingolimod Nanoemulsions at Different Particle Sizes Define the Fate of Spinal Cord Injury Recovery

Spinal cord injury (SCI) is a debilitating condition for which no definitive treatment has yet been identified. Notably, it influences other tissues through inflammatory reactions and metabolic disturbances. Therefore, fingolimod (FTY-720), as an FDA-approved inflammatory modulator, would be promising. In the present study, nanocarriers with two distinct monodisperse particle sizes of 60 (nF60) and 190 (nF190) nm were prepared via low-(stirring) and high-energy (probe ultrasound) emulsion oil in water (O/W) methods. Larger nanocarriers showed higher EE% and sustained-release profile than smaller nanocarriers. Neural stem cell (NSC) viability and lactate dehydrogenase (LDH) release were studied in the presence of nanocarriers and free FTY-720. The results indicated that nanocarriers and free FTY-720 enhanced NSC viability compared with the control group. However, nF190 induced significantly less cell membrane damage than nF60. Nanocarriers and free FTY-720 enhanced motor neuron recovery in SCI rats, while body weight and return to bladder reflux by nF190 were significantly higher than those in the nF60 group. Return to bladder reflux might be due to the role of FTY-720 in the regulation of detrusor muscle tone and preservation of the integrity of vessels by acting on endothelial cells. Moreover, nF190 gained higher soleus muscle weight than the free drugs; probably decreasing proinflammatory cytokines in the soleus diminishes muscular atrophy in SCI rats. In summary, it might be said that larger nanocarriers with sustained-release profile and less cell membrane damage seem to be more efficient than smaller ones to manage SCI and enhance bladder reflux. These data will help pharmaceutical companies select the correct particle size for nanodrugs and develop more efficient drug formulations to treat SCI.

Recent advances on drug delivery nanocarriers for cerebral disorders

Pharmacotherapies for brain disorders are generally faced with obstacles from the blood-brain barrier (BBB). There are a variety of drug delivery systems that have been put forward to cross or bypass the BBB with the access to the central nervous system. Brain drug delivery systems have benefited greatly from the development of nanocarriers, including lipids, polymers and inorganic materials. Consequently, various kinds of brain drug delivery nano-systems have been established, such as liposomes, polymeric nanoparticles (PNPs), nanomicelles, nanohydrogels, dendrimers, mesoporous silica nanoparticles and magnetic iron oxide nanoparticles. The characteristics of their carriers and preparations usually differ from each other, as well as their transportation mechanisms into intracerebral lesions. In this review, different types of brain drug delivery nanocarriers are classified and summarized, especially their significant achievements, to present several recommendations and directions for future strategies of cerebral delivery.