Poly(ɛ-Caprolactone) and Poly (L-Lactic-Co-Glycolic Acid) Degradable Polymer Sponges Attenuate Astrocyte Response and Lesion Growth in Acute Traumatic Brain Injury

Abstract

This study evaluated the response of rat brain to 2 degradable polymers (poly (L-lactic-co-glycolic acid) (PLGA), and poly(ɛ-caprolactone) (PCL)), two common materials in tissue engineering. PLGA has been extensively studied in the brain for controlled drug release as injectable microspheres and is generally accepted as biocompatible in that capacity. Biocompatibility in other forms and for different functions in the brain has not been widely studied. PCL was chosen as an alternative to PLGA for its slower degradation and less-acidic pH upon degradation. Porous scaffolds were made from both polymers and implanted into rat cerebral cortex for 1 and 4 weeks. Morphology, defect size, activation of microglia (OX-42) and astrocytes (glial fibrillary acidic protein (GFAP)), infiltration of activated macrophages (major histocompatibility complex (MHC)-II), and ingrowth of neurons (β-tubulin type III (Tuj-1)) and progenitor cells (nestin) were analyzed using hematoxylin and eosin staining and immunofluorescence. PCL induced a lower inflammatory response than PLGA, as demonstrated by lower MHC-II and GFAP expression and greater ingrowth. Both polymers alleviated astrocytic activation and prevented enlargement of the defect. Tuj-1-, nestin-, and GFAP-positive cells were observed growing on both polymers at the peripheries of the sponge implants, demonstrating their permissiveness to neural ingrowth. These findings suggest that both polymers attenuate secondary death and scarring and that PCL might have advantages over PLGA.