Intranasal Delivery of miR133b in a NEO100-Based Formulation Induces a Healing Response in Spinal Cord-Injured Mice

Abstract

Despite important advances in the pre-clinical animal studies investigating the neuroinhibitory microenvironment at the injury site, traumatic injury to the spinal cord remains a major problem with no concrete response. Here, we examined whether (1) intranasal (IN) administration of miR133b/Ago2 can reach the injury site and achieve a therapeutic effect and (2) NEO100-based formulation of miR133b/Ago2 can improve effectiveness. 24 h after a cervical contusion, C57BL6 female mice received IN delivery of miR133b/Ago2 or miR133b/Ago2/NEO100 for 3 days, one dose per day. The pharmacokinetics of miR133b in the spinal cord lesion was determined by RT-qPCR. The role of IN delivery of miR133b on motor function was assessed by the grip strength meter (GSM) and hanging tasks. The activity of miR133b at the lesion site was established by immunostaining of fibronectin 1 (FN1), a miR133b target. We found that IN delivery of miR133b/Ago2 (1) reaches the lesion scar and co-administration of miR133b with NEO100 facilitated the cellular uptake; (2) enhanced the motor function and addition of NEO100 potentiated this effect and (3) targeted FN1 expression at the lesion scar. Our results suggest a high efficacy of IN delivery of miR133b/Ago2 to the injured spinal cord that translates to improved healing with NEO100 further potentiating this effect.

MicroRNA-133b Dysregulation in a Mouse Model of Cervical Contusion Injury

“…We previously reported the efficacy of miR133b in healing the injured spinal cord when administered either intravenously [ 13 ] or intranasally [ 14 ] 24 h after injury. To better understand the dynamics of miR133b in a contusive type of injury, in this study we aimed to determine the changes in the endogenous level of miR133b at (a) the lesion site, (b) proximal and distal sites of the lesion, (c) pre-frontal cortex, and (d) off-targets, such as spleen and lungs, at different time points after SCI.…”

“…We have previously reported that administration of miR133b, either intravenously [ 13 ] or intranasally [ 14 ], in combination with NEO100, a purified version of perillyl alcohol, targeted the microenvironment of the fibrotic scar, leading to improved healing and motor function in a mouse model of cervical contusion injury. While these studies highlighted the beneficial role of miR133b when administered 24 h after spinal cord injury, its local dynamics in the lesion, as well as in other areas of the spinal cord, are not well-known.…”

“…One of our studies has demonstrated that miR133b administered intravenously reaches the contused spinal cord, suggesting the possibility of bypassing the blood–brain barrier and blood–spinal cord barrier [ 13 ]. Furthermore, in a recent study, we have demonstrated that miR133b delivered via intranasal route hours after SCI can be quantified at the lesion scar and this effect was further enhanced when miR133b was co-administered with NEO100 [ 14 ]. Intrigued by the latest finding, in this study, we chose the lungs as one of our off-targets for two reasons.…”

“…Our published data have established that once-a-day intravenous delivery of miR133b with Argonaute 2 (Ago2, an miR stabilizer) for 3 consecutive days starting 24 h after a spinal cord contusion targeted the microenvironment at the injury site via (i) downregulating gene expression for extracellular matrix molecules, such as collagen type 1 alpha 1 ( Col1a1 ) and tenascin N ( Tnn ), at the lesion scar, (ii) decreasing inflammation and lesion scar volume, leading to enhanced forelimb grip function in injured mice [ 13 ]. Recently, we demonstrated that intranasal co-administration of miR133b with NEO100, a highly purified GMP-manufactured perillyl alcohol, resulted in better cellular uptake of miR133b at the lesion and improved healing of the injured spinal cord [ 14 ].…”