February 28, 2009

Stem cells: Human Trial for Spinal Cord Injuries

Geron Corporation just got permission from the FDA to start human clinical trials of a new medication based on human embryonic stem cells. This will be the first clinical trial of a stem cell based therapy in humans. The new therapy is designed to treat acute spinal cord injuries, and hopes to restore function to the damaged tissues. Translation, to make people who are currently paralyzed walk again.

Medical researchers are praising adult stem cells and their more committed kin, progenitor cells, for their ability to produce different types of specialized cells. The potential of using these cells to repair or replace damaged tissue holds great promise for cancer therapies and regenerative medicine.
However, the question that must first be answered is what determines the ultimate fate of a stem or progenitor cell? According to an article from the Berkeley Laboratory, a team of researchers led by Mark LaBarge and Mina Bissell, appear to be well on the road to finding out. Working with unique microenvironment microarrays (MEArrays) of their own creation, LaBarge, Bissell, and their collaborators, a cell and molecular biologists in Berkeley Lab's Life Sciences Division, have shown that the ultimate fate of a stem or progenitor cell in a woman's breast – whether the cell develops normally or whether it turns cancerous – may depend upon signals from multiple microenvironments.
Previous studies on how microenvironments affect the development of adult human stem or progenitor cells have been based on the behaviour of these cells in culture (in vitro) where they are exposed to a single molecular agent. However, when these cells are in an actual human being (in vivo) they are surrounded by a multitude of other cells plus a supporting network of fibrous and globular proteins called the extracellular matrix (ECM), as well as many other nearby molecules, all of which may be simultaneously sending them instructional signals.
The GRNOPC1 Clinical Program
Patients eligible for the Phase I trial must have documented evidence of functionally complete spinal cord injury with a neurological level of T3 to T10 spinal segments and agree to have GRNOPC1 injected into the lesion sites between seven and 14 days after injury. Geron has selected up to seven U.S. medical centers as candidates to participate in this study and in planned protocol extensions. The sites will be identified as they come online and are ready to enroll subjects into the study.

Although the primary endpoint of the trial is safety, the protocol includes secondary endpoints to assess efficacy, such as improved neuromuscular control or sensation in the trunk or lower extremities. Once safety in this patient population has been established and the FDA reviews clinical data in conjunction with additional data from ongoing animal studies, Geron plans to seek FDA approval to extend the study to increase the dose of GRNOPC1, enroll subjects with complete cervical injuries and expand the trial to include patients with severe incomplete (ASIA grade B or C) injuries to enable access to the therapy for as broad a population of severe spinal cord-injured patients as is medically appropriate.

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