Hyaluronic Acid-based Scaffolds for Brain Tissue Engineering - Hyaluronic Acid for Biomedical and Pharmaceutical Applications - page 124

Lesion
cavity

Proteoglycan
upregulation (Glial scar)

Inflammatory cell

Reactive astrocyte

Dystrophic
neurons

Secondary
axon damage

Dying neuron

Axon

sprouting

Axon demyelination

Figure 6.3 Schematic diagram of the processes of wounding
healing, secondary damage, and abortive regeneration in the
CNS. Reproduced with permission from M.T. Fitch and J. Silver,
Experimental Neurology , 2008, 209 , 2, 294. ©2008, Elsevier [16]

The regenerative capacity of damaged brain tissue is greatly inhibited
by the growth inhibitory environment around the lesion cavity [18],
which is mainly attributed to the following reasons: (1) mature
neurons lose their self-renewal capacity and exist in a non-dividing
state; (2) an influx of inflammatory cells and reactive astrocytes
lead to the formation of a glial scar that forms a mechanical barrier
and causes the secondary damage to regrown axons; (3) reactive
astrocytes up-regulate inhibitory molecules such as chondroitin
sulfate proteoglycans; (4) some myelin-associated proteins, including
myelin-associated glycoproterin (MAG), oligodendrocyte-myelin