Cervical Spinal Cord Therapeutics Delivery

Abstract

Objectives-The current series represents a preclinical safety validation study for direct parenchymal microinjection of cellular grafts into the ventral horn of the porcine cervical spinal cord.Methods-Twenty-four 30-40kg female Yorkshire pigs immunosuppressed with cyclosporine underwent cervical laminectomy and ventral horn human neural progenitor cell (hNPC) injection. Groups 1-3 (n=6 pigs each) were undertaken with the intent of assessing the safety of varied injection volumes: 10μl, 25μl, and 50μl injected at 1ul/min, 2.5ul/min, and 5ul/min, respectively. Groups 4 & 5 (n=3 pigs each) received prolonged immunosuppressant pre-treatment in an attempt to demonstrate graft viability. The latter was undertaken in an alternate species (mini-pig vs. Yorkshire farm pig).Results-Neurologic morbidity was observed in one animal and was attributable to the presence of a resolving epidural hematoma noted at necropsy. While instances of ventral horn targeting were achieved in all injection groups with a coordinate-based approach, opportunities exist for improvement in accuracy and precision. A relationship between injection volume and graft site cross sectional area suggested limited reflux. Only animals from Group 5 achieved graft survival at a (t=1wk) survival endpoint.Conclusions-This series demonstrated the functional safety of targeted ventral horn microinjection despite evidence for graft site immune rejection. Improvements in graft delivery may be augmented with an adapter to improve control of the cannula entry angle, intra-operative imaging, or larger graft volumes. Finally, demonstration of long-term graft viability in future preclinical toxicity studies may require tailored immunosuppressive therapies, an allograft construct, or tailored choice of host species.

In vivo tracking of human neural progenitor cells in the rat brain using bioluminescence imaging

“…Importantly, this method is valuable as a tool to discriminate between live and dead cells in vivo . Graft rejection is a major concern in therapeutic applications of hNPC (Riley, Federici et al 2009). Having the capacity to distinguish between live and dead hNPC Luc2 in vivo without histological analysis is an incredibly useful tool as the field moves forward.…”

“…In animal studies, cell survival and migration can be assessed using post-mortem histological analyses (Tang, Shah et al 2003, Behrstock, Ebert et al 2008, Riley, Federici et al 2009). However, a method of in vivo noninvasive, longitudinal cell tracking in clinical settings would be invaluable, allowing scientists to understand cell dynamics in single subjects as well as cohorts and adapt stem/progenitor cell therapies for further studies.…”

Human neural stem cell transplantation in ALS: initial results from a phase I trial

“…This system, previously standardized in animal models [16,17], has now been employed in the first FDA-approved cell-therapy trial for ALS, implanting human neural progenitor cells [18,19]. …”

“…These cells were obtained from spontaneous miscarriages [8] and implanted using a stereotaxic/surgical apparatus and injection procedures similar to those used by Riley and colleagues [17]. …”

In Vivo Tracking of Human Neural Progenitor Cells in the Rat Brain Using Magnetic Resonance Imaging is Not Enhanced by Ferritin Expression

“…Unfortunately, postmortem histology typically used to assess cell survival and migration in animal studies is not clinically applicable, as it does not permit reliable, longitudinal assessment of grafted cell survival, migration, and homing during the patient’s life. The development of noninvasive methods for in vivo hNPC tracking would allow researchers and clinicians to better understand cell migration, homing, and graft rejection (36,43,44) and thus permit stem cell transplants to continue to move toward clinical use.…”