Human neural stem cell grafts in the spinal cord of SOD1 transgenic rats: Differentiation and structural integration into the segmental motor circuitry

Abstract

Cell replacement strategies for degenerative and traumatic diseases of the nervous system depend on the functional integration of grafted cells into host neural circuitry, a condition necessary for the propagation of physiological signals and, perhaps, targeting of trophic support to injured neurons. We have recently shown that human neural stem cell (NSC) grafts ameliorate motor neuron disease in SOD1 transgenic rodents. Here we study structural aspects of integration of neuronally differentiated human NSCs in the motor circuitry of SOD1 G93A rats. Human NSCs were grafted into the lumbar protuberance of 8 week-old SOD1 G93A rats; results were compared to those on control Sprague-Dawley rats. Using pre-embedding immuno-EM, we found human synaptophysin (+) terminals contacting the perikarya and proximal dendrites of host α motor neurons. Synaptophysin (+) terminals had well-formed synaptic vesicles and were associated with membrane specializations primarily in the form of symmetrical synapses. To analyze the anatomy of motor circuits engaging differentiated NSCs, we injected the retrograde transneuronal tracer Bartha-pseudorabies virus (PRV) or the retrograde marker Cholera Toxin B (CTB) into the gastrocnemius muscle/sciatic nerve of SOD1 rats before disease onset and also into control rats. With this tracing, NSC-derived neurons were labeled with PRV but not CTB, a pattern suggesting that PRV entered NSC-derived neurons via transneuronal transfer from host motor neurons but not via direct transport from the host musculature. Our results indicate an advanced degree of structural integration, via functional synapses, of differentiated human NSCs into the segmental motor circuitry of SOD1-G93A rats.

Glycan-dependent binding of galectin-1 to neuropilin-1 promotes axonal regeneration after spinal cord injury

“…Retrograde tracing was performed as previously described 58,59 with some modifications. Briefly, 8 days after SCI, animals were injected with 2.5 ml of CTB conjugated to Alexa fluor 488 dye (CTB; 10 mg/ml; Molecular Probes Inc., Eugene, OR, USA) into the right and left gastrocnemius/sciatic nerve to trace motor circuitry in the spinal cord.…”

Long‐term Phase 1/2 intraspinal stem cell transplantation outcomes in ALS

“…This approach is supported by in vitro and in vivo preclinical studies5, 6, 7, 8, 9 and demonstrated safety of HSSC intraspinal transplantation in Gottingen minipigs,10, 11 data which secured Food & Drug Administration approval to examine HSSC intraspinal transplantation in ALS patients.…”

Lumbar Intraspinal Injection of Neural Stem Cells in Patients with Amyotrophic Lateral Sclerosis: Results of a Phase I Trial in 12 Patients

“…More frequent measurements of individual patients are likely to identify ''noise'' that may not reflect true changes in disease progression. EIM, a newer and potentially more powerful biomarker of clinical progression, was performed at baseline for patients 1-6 and monthly for at least 3 months prior to surgery for patients [7][8][9][10][11][12]. The data are summarized in Figure 2, in which the major parameter, the 50 kHz phase averaged for all six muscles studied, for all 12 patients is plotted against time.…”

“…These cells, expanded in serum-free media more than many passages, have shown therapeutic benefit when injected into the ventral horn area of spinal cord in the G93A rat model of familial ALS [7] and in a rat model of ischemic spinal cord injury [8]. In these motor neuron disease paradigms, the majority of the transplanted HSSCs differentiated into neuronal populations expressing glutamatergic and GABAergic neurotransmitter markers [9]. Very few of the transplanted cells were shown to have characteristics of alpha motor neurons.…”