Making the Right “Star Cells” for Repairing Spinal Cord Injuries :

Stephen Davies PhD.

Spinal cord injury affects a minimum of 1.2 million people in the US, with 11,000 new cases each year. A new study by the Christopher & Dana Reeve Foundation shows that 1 in 50 people live with paralysis—approximately 6 million people in the US alone. The most frequent age at injury is 19 however 55% of SCI victims are aged between 40 and 59 years old. Only 18% of spinal cord injuries result from sports recreation accidents. The leading causes of spinal cord injuries are motor vehicle accidents (over 50%) and falls in the elderly. Approximately half of traumatic spinal cord injuries result in tetraplegia (paralysis in both arms and legs). In addition, severe spinal injuries also creates a host of related, lifelong health conditions and risks such as low levels of immunity, life threatening blood pressure disorders and severe pain syndromes. Despite major advances in post-event medical and rehabilitative care, very few spinal injury patients gain significant neurological function below the level of spinal trauma.

Over the last ten years efforts have accelerated to find an effective therapy with a particular focus on the potential use of stem cell technologies. In the past, several research groups have shown that the majority of stem cells transplanted into spinal injuries turn into astrocytes (“star cells”), a cell type that actually account for 70% of all cells in the human brain and spinal cord. It used to be thought that astrocytes merely provided structural and metabolic support for neurons however scientists now realize that astrocytes play key roles in the growth and function of neural circuits.  Unfortunately past studies showed that the astrocytes made by transplanted stem cells under the control of inflammatory signals within the injured spinal cord completely failed to promote nerve fiber regeneration or functional recovery and even promoted severe pain syndromes. Our research team however took the approach that as very little is known about different types of astrocytes or their functions, it might be possible to make specific sub-types of beneficial astrocytes from stem cells and avoid making those that promote pain.

Our research has resulted in the development of the world’s most effective cell type for repairing spinal cord injuries. By giving the right signaling molecules - bone morphogenetic proteins (BMP) - to a type of nervous system stem cell called glial restricted precursors (GRPs), we have been able to make a subtype of astrocyte we have named GRP Derived Astrocytes BMP or GDAsBMP. We have proven that transplantation of GDAsBMP into experimental rat spinal cord injuries results in levels of nerve fiber regeneration and functional recovery that far exceed those achieved by all other experimental therapies tested to date. Notably, unlike “naïve” stem cells, GDAsBMP do not promote pain syndromes when transplanted into spinal injuries. We have also shown that GDAsBMP can protect injured neurons in the brain from undergoing atrophy, a result that predicts GDAsBMP will be of major benefit in treating many other neurological disorders such as Stroke, Alzheimer’s, Parkinson’s and ALS. Importantly, for the millions of SCI victims worldwide, our latest experiments indicate that GDAsBMP represent a highly promising therapy for long term chronic spinal cord injuries.

Having made a major scientific breakthrough, the challenge now is to speed development of GDA technology so as to be able to initiate spinal cord injury clinical trials within the next 2 to 3 years, a goal we estimate will require a minimum of $7.3 million US.

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