Schaffer, C. | bioRxiv Science

bioRxiv2022

Engineered retrovirus-like Arc extracellular vesicles for the in vivo targeted delivery of mRNA into the brain

Systemic delivery of mRNAs into disease neurons is first limited by the blood-brain-barrier (BBB). Leukocyte-derived extracellular vesicles (EVs) can cross the BBB at inflammatory sites, emerging as promising carriers to target the disease brain. However, efficient mRNA loading into EVs and their uptake by neurons remain challenges. Here we incorporated inside EVs the endogenous retrovirus-like Arc protein capsids, stabilized by Arc 5UTR RNA elements, to effectively load and deliver mRNAs. Produced from self-derived leukocytes, engineered retrotransposon Arc EVs (eraEVs) are immunologically inert with minimal clearance. Equipped with endothelial adhesion molecules from donor leukocytes, circulating eraEVs enter the brain enriching at neuro-inflammatory sites. During self-assembly, Arc recruits enveloping proteins onto eraEVs further promoting neuronal uptake. Possessing high effectiveness like viral vectors and biocompatibility as natural vesicles, eraEV-nanocarriers can be produced from virtually all donor cell types, potentially leading to the development of future clinical therapies for a range of diseases. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/518870v2_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@260a4aorg.highwire.dtl.DTLVardef@16da754org.highwire.dtl.DTLVardef@4a79dorg.highwire.dtl.DTLVardef@1983da8_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2021

Hypoxia induced carbonic anhydrase mediated dorsal horn sensory neuron activation and induction ofneuropathic pain

Neuropathic pain such as that seen in diabetes mellitus, results in part from central sensitisation in the spinal cord dorsal horn. However, the mechanisms responsible for such sensitisation remain unclear. There is evidence that disturbances in the integrity of the spinal vascular network can be a causative factor in the development of neuropathic pain. Here we show that reduced blood flow and vascularity of the dorsal horn leads to the onset of neuropathic pain. Using rodent models (type 1 diabetes and an inducible endothelial specific vascular endothelial growth factor receptor 2 knockout mouse) that result in degeneration of the endothelium in the dorsal horn we show that spinal cord vasculopathy results in nociceptive behavioural hypersensitivity. This also results in increased hypoxia in dorsal horn sensory neurons, depicted by increased expression of hypoxia markers hypoxia inducible factor 1, glucose transporter 3 and carbonic anhydrase 7. Furthermore, inducing hypoxia via intrathecal delivery of dimethyloxalylglycine leads to the activation of dorsal horn sensory neurons as well as mechanical and thermal hypersensitivity. This shows that hypoxic signalling induced by reduced vascularity results in increased hypersensitivity and pain. Inhibition of carbonic anhydrase activity, through intraperitoneal injection of acetazolamide, inhibited hypoxia induced pain behaviours. This investigation demonstrates that induction of a hypoxic microenvironment in the dorsal horn, as occurs in diabetes, is an integral process by which sensory neurons are activated to initiate neuropathic pain states. This leads to the conjecture that reversing hypoxia by improving spinal cord microvascular blood flow could reverse or prevent neuropathic pain.

neuroscience↗