Extracellular vesicles, in particular the subclass exosomes, are rapidly emerging as a novel therapeutic platform. However, currently very few clinical validation studies and no clearly defined manufacturing process exist. As exosomes progress towards the clinic for treatment of a vast array of diseases, it is important to define the engineering basis for their manufacture early in the development cycle to ensure they can be produced cost-effectively at the appropriate scale. We hypothesize that transitioning to defined manufacturing platforms will increase consistency of the exosome product and improve their clinical advancement as a new therapeutic tool. We present manufacturing technologies and strategies that are being implemented and consider their application for the transition from bench-scale to clinical production of exosomes.

Growing interest in extracellular vesicles (EVs, including exosomes and microvesicles) as therapeutic entities, particularly in stem cell‐related approaches, has underlined the need for standardization and coordination of development efforts. Members of the International Society for Extracellular Vesicles and the Society for Clinical Research and Translation of Extracellular Vesicles Singapore convened a Workshop on this topic to discuss the opportunities and challenges associated with development of EV‐based therapeutics at the preclinical and clinical levels. This review outlines topic‐specific action items that, if addressed, will enhance the development of best‐practice models for EV therapies. Stem Cells Translational Medicine 2017;6:1730–1739

Inward rectifying potassium channels facilitate cell-to-cell communication in hamster retractor muscle feed arteries.

This study sought to define whether inward rectifying K(+) (K(IR)) channels were modulated by vasoactive stimuli known to depolarize and constrict intact cerebral arteries. Using pressure myography and patch-clamp electrophysiology, initial experiments revealed a Ba(2+)-sensitive K(IR) current in cerebral arterial smooth muscle cells that was active over a physiological range of membrane potentials and whose inhibition led to arterial depolarization and constriction. Real-time PCR, Western blot, and immunohistochemical analyses established the expression of both K(IR)2.1 and K(IR)2.2 in cerebral arterial smooth muscle cells. Vasoconstrictor agonists known to depolarize and constrict rat cerebral arteries, including uridine triphosphate, U46619, and 5-HT, had no discernable effect on whole cell K(IR) activity. Control experiments confirmed that vasoconstrictor agonists could inhibit the voltage-dependent delayed rectifier K(+) (K(DR)) current. In contrast to these observations, a hyposmotic challenge that activates mechanosensitive ion channels elicited a rapid and sustained inhibition of the K(IR) but not the K(DR) current. The hyposmotic-induced inhibition of K(IR) was 1) mimicked by phorbol-12-myristate-13-acetate, a PKC agonist; and 2) inhibited by calphostin C, a PKC inhibitor. These findings suggest that, by modulating PKC, mechanical stimuli can regulate K(IR) activity and consequently the electrical and mechanical state of intact cerebral arteries. We propose that the mechanoregulation of K(IR) channels plays a role in the development of myogenic tone.

Elevation of the intracellular free Ca 2؉ concentration regulates many functional responses in airway smooth muscle, including contraction, proliferation, adhesion, and cell survival. This increase in calcium can be achieved by a release from internal stores (sarcoplasmic reticulum) and/or entry across the cell membrane from the extracellular environment. The molecular identity of this calcium influx pathway in human airway smooth muscle (HASM) remains unclear. Functional studies using Fluo 4-loaded HASM suggest the presence of a histamine H 1 receptor-activated Ca 2؉ entry pathway with characteristics similar to those seen with transient receptor potential (TRP) family homologs. Using a range of molecular and cell biological approaches we defined the expression pattern of transient receptor potential classics (TRPC) homologs in airway cells and tissue. Here we show that HASM and human bronchial epithelial cells both express TRPC1,-4, and-6, with HASM also expressing TRPC3 at the mRNA level. Identification of TRPC6 protein by western blot and confocal microscopy indicated that the protein is localized in specific cell types, suggesting that it plays an important role in regulating key functions in airway cells. These data demonstrate the expression of a range of TRPC homologs in the airway and the presence of a functional Ca 2؉ entry pathway with characteristics typical of TRPC family members. TRPC homologs may provide an important novel target for the treatment of airway disease. Calcium homeostasis plays a key role in the regulation of many functional responses in airway cells. In airway smooth muscle (ASM), elevation of intracellular Ca 2ϩ levels promotes contraction and plays a role in cell proliferation, adhesion, and survival (1). The source of Ca 2ϩ for these responses has become clear over recent years. The initial contractile response of ASM is dependent upon the release of Ca 2ϩ from intracellular stores as a consequence of receptor-mediated inositol 1,4,5 triphosphate (IP 3) formation (2). However, the sustained elevation of intracellular free Ca 2ϩ concentration ([Ca 2ϩ ] i), which occurs in response to stimulation with agonists such as bradykinin and histamine,