A paper in this week's issue of the journal Science (Restoring Voluntary Control of Locomotion after Paralyzing Spinal Cord Injury, Courtine et al., Science, VOL 336, June 1, 2012) describes an experiment in which rats regain control over their paralyzed limbs after a spinal cord injury.

Dr. Pierre Guertin, Professor, Department of Psychiatry and Neurosciences, Laval University, Quebec

“1) The type of experimental lesion (partly at T7 and, a few segments away, partly at T10) proposed in this study is generally not found in man.  Although useful for this demonstration in an animal model, comparable findings are unlikely to occur in man for that fundamental reason.

“2) The authors report that in untreated animals, no sign of recovery is found (meaning 'detected') during at least 2 months post-injury. This is in clear contrast with findings from our laboratory and others describing clear and significant signs of spontaneously occuring (involuntary) non-locomotor and locomotor-like movements in the hindlimbs of completely spinal transected rodents (see e.g., Guertin 2005; Lapointe et al. 2006; Ung et al. 2007)

“3) They also forgot to mention that proper training and sensory stimulation (e.g., tail pinching, perineal region pinching) itself (i.e., without pharmacotherapy) has been known for years to trigger episodes of moreless weight bearing locomotion in completely spinal transected cats (Lovely et al. 1986; Belanger et al. 1996)

“4) The authors forgot to report that Guertin and colleagues have already revealed the existence of pro-locomotor-inducing drugs (capable of acutely inducing weight bearing stepping in completely spinal transected mice) with only two drugs of their tritherapy cocktail (including 5-HT (5-HT1A) receptor agonists + dopamine (D1) receptor agonists (Lapointe and Guertin, 2008).

“5) Moreover, a superior cocktail that is entirely active upon oral administration (and without the need of electrical stimulation) has been developed already. It has been shown to induce episodes of weight-bearing stepping in completely spinal transected mice (Guertin et al. 2010). In fact, it is already a patented technology filed by Laval University (for which I am the inventor) (patent has been issued by US patent & trade organization, see attached doc) called Spinalon. This cocktail has currently entered clinical development level in spinal cord injured patients under licensing agreement with a Canadian company called Nordic Life Science Pipeline.

“6) Hence, the novelty does not rely on the induction of episodes of locomotor movements in completely paraplegic animals (as demonstrated above) but, instead, in some supraspinal plasticity events that promote somehow the induction of locomotor episodes essentially driven by chemical and electrical stimulation (and proprioceptive reflexes).

“7) In conclusion, as they mentioned themselves towards the end of the article, their approach did not lead to a recovery of voluntary induced stepping. Only involuntary stepping was described (but already described by other means in our lab as well as in other laboratories).

“8) All in all, given that i) the approach proposed by the authors is rather invasive (drugs used including 8-OH-DPAT and SKF81297 have to be injected subcutaneously or intraperitoneally since non-active upon oral administration), ii) as such, it is likely to encounter numerous hurdles prior to approval of a safe combinatorial approach by regulatory authorities (Health Canada, Food and Drug Administration), iii) their approach illegally takes advantage of patent protected technologies (infringed patent protection provided by US patent no. 8,012,481), I tend to believe that future development of this approach will be difficult.”