Neuronal Differentiation of Cartilage-derived Stem Cells In Vitro and their Delivery to the Spinal Cord in a Mouse Model of ALS Using MRI-guided Focused Ultrasound

Amyotrophic Lateral Sclerosis (ALS) is an incurable neurodegenerative disorder for which stem cells are attractive therapeutic interventions. However, the complications of immunosuppression for allografts and invasive surgeries for blood-spinal cord barrier (BSCB) penetration have hampered their success. First, we investigated the in vitro neuronal differentiation potential of immunosuppressive, cartilage-derived stem cells (CDCSs). Next, we examined the safety and survival of intravenously injected, GFP-expressing, neuronally-differentiated CDSCs in an ALS mouse model (SOD-G93A), following MRI-guided focused ultrasound (MRIgFUS)-mediated opening of the BSCB. CDSCs’ neuronal differentiation was successful. GFP+ cells were not detected within the spinal cords of treated mice; no behavioural improvements were noted. Despite lack of efficacy, disease onset and survival in treated SOD1-G93A mice remained similar to the control SOD1-G93A mice, indicating that treatment did not hamper motor performance. This is the first study to demonstrate neuronal differentiation of CDSCs and feasibility of MRIgFUS-mediated BSCB opening in SOD1-G93A mice.M.Sc

Focused Ultrasound-Induced Neurogenesis Requires an Increase in Blood-Brain Barrier Permeability

<div><p>Transcranial focused ultrasound technology used to transiently open the blood-brain barrier, is capable of stimulating hippocampal neurogenesis; however, it is not yet known what aspects of the treatment are necessary for enhanced neurogenesis to occur. The present study set out to determine whether the opening of blood-brain barrier, the specific pressure amplitudes of focused ultrasound, and/or the intravenous administration of microbubbles (phospholipid microspheres) are necessary for the enhancement of neurogenesis. Specifically, mice were exposed to burst (10ms, 1Hz burst repetition frequency) focused ultrasound at the frequency of 1.68MHz and with 0.39, 0.78, 1.56 and 3.0MPa pressure amplitudes. These treatments were also conducted with or without microbubbles, at 0.39 + 0.78MPa or 1.56 + 3.0MPa, respectively. Only focused ultrasound at the ~0.78 MPa pressure amplitude with microbubbles promoted hippocampal neurogenesis and was associated with an increase in blood-brain barrier permeability. These results suggest that focused ultrasound -mediated neurogenesis is dependent upon the opening of the blood-brain barrier.</p></div

Focused Ultrasound-Induced Neurogenesis Requires an Increase in Blood-Brain Barrier Permeability - Fig 1

<p>Representative post-sonication T1-weighted MR images of animals in (A) group 1 (~0.78 MPa pressure amplitudes with microbubbles), (B) group 2 (0.39MPa pressure amplitudes with microbubbles), (C) group 3 (1.56MPa pressure amplitudes without microbubbles), and (D) group 4 (3.0MPa pressure amplitudes without microbubbles). Only animals that received ~0.78MPa pressure amplitudes and microbubbles showed significant opening of the blood-brain barrier. Arrow indicates area of BBB opening.</p

The average number of mature and immature neurons colabelled with BrdU in each slice of the dentate gyrus.

<p>Animals were from group 1 (~0.78 MPa pressure amplitudes with microbubbles). Error bars represent the standard error of the mean. † = 0.061, *<i>p</i> = 0.021.</p

Specifications of focused ultrasound treatments for each group.

<p>Specifications of focused ultrasound treatments for each group.</p