Skin Stem Cells for Nerve Regeneration

Milan, Italy -

One approach to nervous system repair after injury involves implantation of "guide tubes", which has the name implies, preferentially induces regenerating neural cells to migrate into a desired direction.

The question, of course, is what type of neural progenitors should one use in conjunction with such guide tubes. Embryonic stem cells have the disadvantage of potentially uncontrolled differentiation and teratoma formation, whereas autologous stem cells are often difficult to extract (eg bone marrow suction).

It was published recently that skin derived stem cells can be implanted in animal models of nerve injury and effectively promote neural regeneration. Specifically, the recent paper (Marchesi et al. Skin-derived stem cells transplanted into resorbable guides provide functional nerve regeneration after sciatic nerve resection. Glia. 2007 Jan 3) described a rat model of sciatic nerve injury (nerve gap of 16 mm) that was treated wtih autologous GFP-labeled skin derived stem cells using two types of guides. The first guide was synthetic, generated by dip coating with a L-lactide and trimethylene carbonate copolymer and the second was a collagen-based guide.

Efficacy was assessed using the sciatic function index and the compound muscle action potential. These parameters improved significantly after treatment with the skin derived stem cells using the collagen guide.

Since GFP positive cells expressed the neural markers S-100, glial fibrillary acidic protein and myelin basic protein, it appears that the skin derived stem cells were capable of differentiating into a neural type that appears to appropriately regenerate sciatic nerve injury.

The question still remains how much the actual differentiation of the cells contributed to the functional recovery, versus the impact that the stem cell derived growth factors contributed the regeneration of the endogenous nerve stem cells.