The Spark of Life: Engaging the Cortico-Truncoreticulo-Propriospinal Pathway by Electrical Stimulation

Stem cell-derived neuronal relay strategies and functional electrical stimulation for treatment of spinal cord injury

The inability of adult mammals to recover function lost after severe spinal cord injury (SCI) has been known for millennia and is mainly attributed to a failure of brain-derived nerve fiber regeneration across the lesion. Potential approaches to re-establishing locomotor function rely on neuronal relays to reconnect the segregated neural networks of the spinal cord. Intense research over the past 30 years has focused on endogenous and exogenous neuronal relays, but progress has been slow and the results often controversial. Treatments with stem cell-derived neuronal relays alone or together with functional electrical stimulation offer the possibility of improved repair of neuronal networks. In this review, we focus on approaches to recovery of motor function in paralyzed patients after severe SCI based on novel therapies such as implantation of stem cell-derived neuronal relays and functional electrical stimulation. Recent research progress offers hope that SCI patients will one day be able to recover motor function and sensory perception.

Bridging the gap: Spinal cord fusion as a treatment of chronic spinal cord injury

Despite decades of animal experimentation, human translation with cell grafts, conduits, and other strategies has failed to cure patients with chronic spinal cord injury (SCI). Recent data show that motor deficits due to spinal cord transection in animal models can be reversed by local application of fusogens, such as Polyethylene glycol (PEG). Results proved superior at short term over all other treatments deployed in animal studies, opening the way to human trials. In particular, removal of the injured spinal cord segment followed by PEG fusion of the two ends along with vertebral osteotomy to shorten the spine holds the promise for a cure in many cases.

Engraftment, neuroglial transdifferentiation and behavioral recovery after complete spinal cord transection in rats

Background:

Proof of the efficacy and safety of a xenogeneic mesenchymal stem cell (MSCs) transplant for spinal cord injury (SCI) may theoretically widen the spectrum of possible grafts for neuroregeneration.

Methods:

Twenty rats were submitted to complete spinal cord transection. Ovine bone marrow MSCs, retrovirally transfected with red fluorescent protein and not previously induced for neuroglial differentiation, were applied in 10 study rats (MSCG). Fibrin glue was injected in 10 control rats (FGG). All rats were evaluated on a weekly basis and scored using the Basso–Beattie–Bresnahan (BBB) locomotor scale for 10 weeks, when the collected data were statistically analyzed. The spinal cords were then harvested and analyzed with light microscopy, immunohistochemistry, and immunofluorescence.

Results:

Ovine MSCs culture showed positivity for Nestin. MSCG had a significant and durable recovery of motor functions (P <.001). Red fluorescence was found at the injury sites in MSCG. Positivity for Nestin, tubulin βIII, NG2 glia, neuron-specific enolase, vimentin, and 200 kD neurofilament were also found at the same sites.

Conclusions:

Xenogeneic ovine bone marrow MSCs proved capable of engrafting into the injured rat spinal cord. Transdifferentiation into a neuroglial phenotype was able to support partial functional recovery.

PROJECT HEAVEN: Preoperative Training in Virtual Reality

A cephalosomatic anastomosis (CSA; also called HEAVEN: head anastomosis venture) has been proposed as an option for patients with neurological impairments, such as spinal cord injury (SCI), and terminal medical illnesses, for which medicine is currently powerless. Protocols to prepare a patient for life after CSA do not currently exist. However, methods used in conventional neurorehabilitation can be used as a reference for developing preparatory training. Studies on virtual reality (VR) technologies have documented VR's ability to enhance rehabilitation and improve the quality of recovery in patients with neurological disabilities. VR-augmented rehabilitation resulted in increased motivation towards performing functional training and improved the biopsychosocial state of patients. In addition, VR experiences coupled with haptic feedback promote neuroplasticity, resulting in the recovery of motor functions in neurologically-impaired individuals. To prepare the recipient psychologically for life after CSA, the development of VR experiences paired with haptic feedback is proposed. This proposal aims to innovate techniques in conventional neurorehabilitation to implement preoperative psychological training for the recipient of HEAVEN. Recipient's familiarity to body movements will prevent unexpected psychological reactions from occurring after the HEAVEN procedure.

The history of head transplantation: a review

Background

Since the turn of the last century, the prospect of head transplantation has captured the imagination of scientists and the general public. Recently, head transplant has regained attention in popular media, as neurosurgeons have proposed performing this procedure in 2017. Given the potential impact of such a procedure, we were interested in learning the history of the technical hurdles that need to be overcome, and determine if it is even technically possible to perform such a procedure on humans today.

Method

We conducted a historical review of available literature on the technical challenges and developments of head transplantation. The many social, psychological, ethical, religious, cultural, and legal questions of head transplantation were beyond the scope of this review.

Results

Our historical review identified the following important technical considerations related to performing a head transplant: maintenance of blood flow to an isolated brain via vessel anastomosis; availability of immunosuppressive agents; spinal anastomosis and fusion following cord transfection; pain control in the recipient. Several animal studies have demonstrated success in maintaining recipient cerebral perfusion and achieving immunosuppression. However, there is currently sparse evidence in favor of successful spinal anastomosis and fusion after transection. While recent publications by an Italian group offer novel approaches to this challenge, research on this topic has been sparse and hinges on procedures performed in animal models in the 1970s. How transferrable these older methods are to the human nervous system is unclear and warrants further exploration.

Conclusions

Our review identified several important considerations related to performing a viable head transplantation. Besides the technical challenges that remain, there are important ethical issues to consider, such as exploitation of vulnerable patients and informed consent. Thus, besides the remaining technical challenges, these ethical issues will also need to be addressed before moving these studies to the clinic.

Neurologic foundations of spinal cord fusion (GEMINI)

Cephalosomatic anastomosis has been carried out in both monkeys and mice with preservation of brain function. Nonetheless the spinal cord was not reconstructed, leaving the animals unable to move voluntarily. Here we review the details of the GEMINI spinal cord fusion protocol, which aims at restoring electrophysiologic conduction across an acutely transected spinal cord. The existence of the cortico-truncoreticulo-propriospinal pathway, a little-known anatomic entity, is described, and its importance concerning spinal cord fusion emphasized. The use of fusogens and electrical stimulation as adjuvants for nerve fusion is addressed. The possibility of achieving cephalosomatic anastomosis in humans has become reality in principle.

Fusogen-assisted rapid reconstitution of anatomophysiologic continuity of the transected spinal cord

The GEMINI spinal cord fusion protocol exploits the ability of so-called fusogens, such as polyethylene glycol (PEG), to achieve rapid neural restoration of electrical continuity across the ends of a transected spinal cord. Experimental evidence suggests that motor recovery can occur after complete transection of the cervical and dorsal spinal cord in mice and rats following application of PEG. This allows for the possibility of spinal cord "reconstruction" in humans and even the possibility of head transplantation in the future.