Gw. Plant et al., AXONAL GROWTH WITHIN POLY(2-HYDROXYETHYL METHACRYLATE) SPONGES INFILTRATED WITH SCHWANN-CELLS AND IMPLANTED INTO THE LESIONED RAT OPTIC TRACT, Brain research, 671(1), 1995, pp. 119-130
Porous hydrophilic sponges made from 2-hydroxyethyl methacrylate (HEMA
) have a number of possible biomedical applications. We have investiga
ted whether these poly(HEMA) hydrogels, when coated with collagen and
infiltrated in vitro with cultured Schwann cells, can be implanted int
o the lesioned optic tract and act as prosthetic bridges to promote ax
onal regeneration. Nineteen rats (20-21 days old) were given hydrogel/
Schwann cell implants. No obvious toxic effects were seen, either to t
he transplanted glia or in the adjacent host tissue. Schwann cells sur
vived the implantation technique and were immunopositive for the low a
ffinity nerve growth factor receptor, S100 and laminin. Immunohistoche
mical studies showed that host non-neuronal cells (astrocytes, oligode
ndroglia and macrophages) migrated into the implanted hydrogels. Astro
cytes were the most frequently observed host cell in the polymer bridg
es. RT97-positive axons were seen in about two thirds of the implants.
The axons were closely associated with transplanted Schwann cells and
, in some cases, host glia (astrocytes). Individual axons regrowing wi
thin the implanted hydrogels could be traced for up to 900 mu m, showi
ng that there was continuity in the network of channels within the pol
ymer scaffold. Axons did not appear to be myelinated by either Schwann
cells or by migrated host oligodendroglia. In three rats, anterograde
tracing with WGA/HRP failed to demonstrate the presence of retinal ax
ons within the hydrogels. The data indicate that poly(HEMA) hydrogels
containing Schwann cells have the potential to provide a stable three-
dimensional scaffold which is capable of supporting axonal regeneratio
n in the damaged CNS.