Introduction: Amyotrophic Lateral Sclerosis (ALS) is a fatal and relentlessly progressive neurodegenerative disease with a median survival after symptom onset that ranges from 2 to 5 years. The only FDA approved treatment, riluzole, prolongs this survival by a matter of months. Cell therapies for ALS attempt to restore motor function through replacement of neuronal and non-neuronal cells. Multiple clinical trials using this approach are now underway in many countries around the world. The current study tested the spinal cord’s tolerance to increasing volumes and number of injections in Gottingen minipigs.
Methods: Twenty-five female minipigs received human neural progenitor cell injections using a stereotactic platform device developed by our group at Emory. Cell transplantation in groups 1 to 5 (n = 5 pigs each) was undertaken with the intent of assessing the safety of an injection volume escalation (10, 25, and 50 microL) and an injection number escalation (20, 30 and 40 injections). Sensory and motor function, as well as general morbidity was assessed for 21 days. Full necropsy was performed; spinal cords were analyzed for graft survival and microscopic tissue damage.
Results: No mortality or permanent surgical complications were observed within the 21-day study period. All animals returned to preoperative baseline within 14 days, showing complete motor function recovery. The histological analysis of the tissue showed that there was no significant decrease in neuronal density between groups and the engraftment percentage ranged from 11-31% depending on the injection paradigm. However, significant tissue damage was identified when injecting high volumes into the spinal cord (> 25 microL).
Conclusions: This series supports the functional safety of various injection volumes and numbers in the spinal cord, and gives critical insight to important safety thresholds. The results from this study are relevant to all translational programs delivering cell therapeutics to the spinal cord.
Patient Care: This work demonstrates the functional safety of escalating microinjection volume and number in the cervical spinal cord, while defining important safety thresholds. These findings are relevant to all translational programs currently attempting to deliver cellular therapeutics to the spinal cord in humans. More importantly, this work provides critical information for the application of human embryonic stem cells in the treatment of ALS and other neurodegenerative diseases.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Recognize the application of human embryonic stem cells in the treatment of ALS and other neurodegenerative diseases, 2) Understand the tolerance of the cervical spinal cord to direct stem cell injection, 3) Identify important safety thresholds across a wide range of injection parameters.