Glial scar formation

After postcommissural fornix transection (Lips et al., 1995) and after optic nerve lesion (Ajemian et al., 1994) in adult rat, induced astroglial expression of tenascin is restricted to the border zone of the lesion. It is interesting to note that the local distribution of tenascin immunoreac-tivity at the lesion site of the transected fornix and the sprouting pattern of the injured axons as shown by Lips et al. (1995) is not compatible with a previously suggested putative axon growth inhibitory function of tenascin in vivo (McKeon et al., 1991). Furthermore, in the tenascin knockout mouse glial scar formation is not altered as compared to wildtype animals (Steindler et al., 1995). 

Hsu lY, Bourguignon LY, Adams CM, Peyrollier K, Zhang H, Fandel T, Cun CL, Werb Z, Noble-Haeusslein LI (2008) Matrix metaUoproteinase-9 facilitates glial scar formation in the injured spinal cord. 1 Neurosci 28 13467-13477... 

Tysseling-Mattiace VM, Sahni V, Niece KL, Bitch D, Czeisler C, Fehlings MG, Stupp SI, Kessler JA (2008) Self-assembling nanofibers inhibit glial scar formation and promote axon elongation after spinal cord injury. J Neurosci 28 3814-3823. doi 10.1523/JNEUROSCI. 0143-08.2008... 

An ECM protein, laminin, which participates in neuronal development and survival, can be immobilised on the backbone of the HA hydrogel, and this has been proven by Hou and co-workers [21]. In this case, the gel still possesses the mechanical properties and rheological behaviour similar to brain tissue. After being implanted into a cortical lesion it promotes neurite extension and angiogenesis into the porous scaffold, and simultaneously inhibits glial scar formation. 

HA is a popular material for brain tissue regeneration because it is normally present in high levels in the ECM of connective, epithelial and neural tissues [31, 32]. HA is known to play roles in cellular processes like cell proliferation, morphogenesis, inflammation, and wound repair [33]. It has also been reported that HA scaffolds could reduce glial scar formation after implantation [34], The recent progress on HA-based scaffolds for brain regeneration is briefly summarised in the following section. 

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