Intracerebral implantation of ionic synthetic hydrogels: effect of polar substrata on astrocytosis and axons.
In previous studies, hyperporous synthetic hydrogels of poly(glyceryl methacrylate) or p(GMA), containing bioadhesive substrates of collagen, were implanted into rat cerebral tissue in order to provide systems of oriented guidance channels for directing the growth of the scar and axons /28/. In the present study, ionic p(GMA)-collagen hydrogels containing polar chemical groups, either basic amino groups or acidic carboxyl groups, were evaluated for their tolerance and their effects on the brain scarring response and axonal reactivity after long-term implantation in the cerebral cortex. In all animals, the implants were well tolerated. Although both types of gels influenced the astroglial reaction near the bioimplant, hydrogels carrying carboxyl groups had the strongest influence on the elongation, the direction and the organization of astrocytic processes so that a glial matrix could form in regions of the gel. Extracellular material (e.g. reticulin) was also deposited into the gels carrying carboxyl groups. Although cortical nerve fibers in the surrounding tissue showed a regenerative response, extending onto or into the matrices, this behavior seemed to depend more on the organization of the astrocytic scar imposed by the gel than on the type of gel. We conclude that matrices carrying negatively charged groups influence favorably the astrocytosis and the deposition of connective tissue, and that this approach represents a new avenue in attempting to modulate the brain scar formation.
Woerly
S
S
Centre de recherche en neurobiologie, Hôpital de l'Enfant Jésus, Université Laval, Québec, Canada.
Lavallée
C
C
Marchand
R
R
D000818:Animals; D001253:Astrocytes / Q000187:drug effects*; D001369:Axons / Q000187:drug effects*; D001921:Brain / Q000033:anatomy & histology; D016380:Brain Tissue Transplantation / Q000502:physiology*; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000187:drug effects / Q000637:transplantation; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000276:immunology / Q000378:metabolism; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007150:Immunohistochemistry; D008855:Microscopy, Electron, Scanning; D009416:Nerve Regeneration; D010525:Peripheral Nerves / Q000187:drug effects; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D005904:Glial Fibrillary Acidic Protein; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols