1) Dr. Fernando Ramirez (Mexico)

2) Diacrin Corporation (USA)

3) Dr. Hui Zhu (China)

4) Drs. Masoumeh Firouzi, Hooshang Sabveri (Iran)

1) Dr. Fernando Ramirez’team (Tijuana, Mexico), starting in the early 1990’s, has transplanted blue-shark, embryonic neuronal cells (i.e., xenogeneic transplantation) into the injured spinal cord of 89 patients with SCI. His approach evolved from live-cell therapies developed by European scientists starting in the 1930s long before stem cells emerged as a hot scientific topic. Although his work is still considered controversial, it is less so today than when he started his work because of all the other cell-transplantation work that has since been initiated. More recently, the program has shifted to the use of umbilical cord stem cells (www.ramirezdelrio.com).

2) The Diacrin Corporation (Massachusetts, USA) sponsored another xenotransplantation clinical trial. Specifically, Drs John McDonald (St. Louis, Missouri) and Darryl DiRisio (Albany, New York) injected about 14-million, immature, fetal pig, myelin cells into the cord surrounding the injury site of 10 patients with chronic SCI. The purpose of these cells was to remyelinate neurons that have lost their insulating myelin sheaths due to injury, in turn, restoring conduction potential. Because the expression of immune-provoking proteins located on the porcine cell surface was altered, the need for immune-suppressing drugs was supposedly greatly reduced.

Few results were reported for this clinical trial. According to a December 2002 investment report, the survival of the transplanted porcine cells was minimal, even with immunosuppressant drugs.

3) Dr. Hui Zhu (Kunming, China): As reported at the 1st International SCI Treatments & Trials Symposium, Hong Kong, December 2005, Dr. Hui Zhu and colleagues have transplanted fetal Schwann cells into 40 individuals with complete paraplegia. Thirty-two were men and eight were women; age ranged from 18-58 (average 31) years; and time between injury and transplantation ranged from 1-19 years, i.e., all were chronic injuries. Patients were followed for 3-24 months using ASIA assessments, MRI imaging, and various electrophysiological evaluations.

Procedurally, Schwann cells cultured from fetal human sciatic nerve (a nerve that runs through upper leg) were implanted into the patient’s injury cyst or cavity. After surgery, patients received ambulatory training. Although a few regained substantial improvements, in most patients improvements were slight as measured by ASIA evaluations of motor function and light and deep sensation. In some patients, the MRI and electrophysiological assessments indicated partial recovery of spinal-cord function.

At the aforementioned symposium, Zhu showed a case-study video of a young man who regained substantial function due to the intervention.  

4) Drs. Masoumeh Firouzi, Hooshang Sabveri and colleagues (Tehran, Iran) have also transplanted Schwann cells into the injury site. As indicated earlier, these neuronal support cells remyelinate axons in the peripheral nervous system, which, unlike the central nervous system has considerable inherent regenerative potential.

This human trial builds upon on a recently published study using rats with an experimental contused injury, the sort of injury that is most common in humans (Neurosci Lett, 402(1-2), 2006). In this study, Schwann cells were injected into the subarachnoid space surrounding the spinal cord.  Compared to control animals, the treated rats regained more locomotion after injury and had more spared axons.

Given these results, the investigators received permission from the Tehran University of Medical Sciences’ ethical committee to transplant Schwann cells into 20 patients with SCI. The cells were isolated from a sural nerve in back of the patient’s calf (i.e., autologous cells with no rejection potential) and cultured in a sterile laboratory for two to five weeks. The cultured cells were then implanted back into the injury site.

Initially, nine of the 20 authorized patients were treated. This study excluded individuals older than 50, whose cord has been transected, and whose injury site is considered too extensive. A number of the treated patients had long-term chronic injuries, including patients 16, 23, 25 years post injury. Using the data coming out this preliminary study, more definitive criteria will be developed on the most appropriate post-injury, treatment window.

Three to six months after implantation, no adverse side effects have been observed. According to Dr. Firouzi, all treated patients “have shown some degree of sensory recovery; most have motor recovery findings using quantitative (digital) motor evaluations; and some showed sphincter and sexual improvement, all compared to the patient’s steady-state before the transplantation. Three of them can walk now (two using parallel bars and one using walker).” The investigators note that progress should continue for some time after this limited follow-up period.

The remaining 20 patients are now being treated. The investigators intend to report their results at international conferences and in professional journals. Preliminary preparations are being made to develop facilities and train other doctors to make this function-restoring intervention more accessible to the general SCI community.

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