Comparison of supportive effect among hydrogel, matrigel, poly-L lactic acid (PLLA) scaffold incorporating neural stem cells in the motor cortex-ablated corticectomy rat model via in vivo bioluminescence imaging

Abstract

Purpose: Recent studies have tried to enhance efficiency of cell therapy for neurodegenerative disease using biocompatible scaffolds that can provide machenical support. Among a wide variety types of scaffolds, evaluating which scaffolds play an effective roles in promoting the implanted cell growth and proliferation in vivo is important for determining the properly available scaffolds capable of enhancing thearpeutic effect. In this study, we compared three different scaffolds, hydrogel, matrigel, poly-L lactic acid (PLLA) scaffold to evaluate the supportive effect of individual scaffold using in vivo optical imaging system in corticectomized rat model. Material and Method: Enhanced firefly luciferase (effluc) retroviral vector system was introduced to evaluate the survival of human neural stem cells within each scaffold in vivo. The gelatin-polyethylene glycol-tyramine (GPT) hydrogel was prepared from a Tet-SA-TA solution in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) under physiologic condition. PLLA scaffold was also prepared in 24 well plate by wetting in 70% ethanol over 24 hr before cell incorporation step. The corticectomized rat model that excises an area of cerebral motor cortex was established. The immune suppressor was daily administered via intraperitoneal injection into corticectomized rat model after cell implantation. The behavioral test was performed to evaluate functional recovery in brain injury model. In vivo optical images were acquired using IVIS-100 optical imaging device. Results: The increasing F3-effluc cell number was linearly correlated with luciferase signal intensity. The luciferase signals were gradually increased in F3-effluc cells incorporated within three different scaffolds, showing highest luciferase intensity in F3-effluc cells within matrigel or PLLA, compared to F3-effluc/hydrogel complex group. While F3-effluc cells implanted into ablated cortical region were only maintained for 6 days in their survival, implanted F3-effluc cells encapsulated within three different scaffolds in corticectomized rat exhibited prolonged survival until 10 days. In quantitative analysis, F3-effluc cells within PLLA scaffold showed the best supportive effect in brain damaged rat model. Immunohistochemistry results revealed that nestin (neural stem cell marker)-positive cell population in cell/scaffold group was higher than cell only-injected group. The expression of Tuj-1, early neuronal marker was co-localized with DiI-labeled implanted F3-effluc cells wihin matrigel or PLLA, compared to cell-only and cell/hydrogel group. Conclusion: In this study, we compared the supportive effect among different biocompatible scaffolds to evaluate the survival and proliferation pattern of F3-effluc incorporated within hydrogel, matrigel, PLLA scaffolds using optical imaging reporter system in vivo. We expect that in vivo optical monitoring system could be helpful to determine the optimal selection for appropriate biocompatible scaffold favorable to the treatment of specific brain injury disorder.