In vivo visualization for supportive effect on viability of transplanted human neural stem cell using biocompatible PLLA scaffold in corticectomized rat brain model

Abstract

Purpose: Adult mammalian central nervous system (CNS) with neuronal loss due to brain traumatic brain injury (TBI) has a limited ability to regenerate the neurologic deficit and thereby cell transplantation therapy offers potential treatment to improve the functional disability associated with neuronal loss. Moreover, tissue engineering has a critical role in survival and proliferation of transplanted stem cells. To observe in vivo survival pattern of the transplanted stem cells within biocompatible scaffold in TBI animal model, we monitored in vivo survival duration of the implanted human neural stem cell (hNSC) supported with poly-L-lactic acid (PLLA) in corticectomized rat model. Methods: Corticectomized rat models were established by motor-cortex ablation from frontal brain of Sprague-Dawley albino (SD) rat. F3-effLuc cells containing enhanced firefly luciferase (effLuc) gene were established through retroviral infection and the F3 cells expressing effLuc were sorted using magnetic-activated cell sorting (MACS) analyzer and assessed through fluorescence-activated cell sorting (FACS) analysis. The F3-effLuc cells within PLLA scaffold was monitored using in vivo imaging system (IVIS-100) 7 days after corticectomized surgery. The metabolic activity of implanted F3-effLuc cells in corticectomized rat was evaluated using animal PET/CT imaging device. Histological data was acquired using luciferase and Tuj1 to identify localization and characterization of the transplanted F3-effLuc. Results: F3-effLuc cells infected with effLuc gene showed the purity of 90.7% via FACS analysis. Gradually increased luciferase signal in F3-effLuc cells was detected on cell number dependent manner. The F3-effLuc within PLLA scaffold implanted in corticectomized rat model showed the higher luciferase intensity than the group of F3-effLuc only. The luciferase signal in F3-effLuc within PLLA scaffold was maintained until 14 days, compared to F3-effLuc cell-implanted group (until 8 days). The motor cortex removal area in corticectomized rat brain was clearly seen by 18F-FDG PET/CT study, and the location of the survived F3-effLuc was found only in PLLA scaffold-mixed group, not in F3-effLuc implanted group 15 days after cell implantation. Co-immunostaining results using luciferase and Tuj1 specific antibody revealed that Tuj1 (early neuronal marker) expression was detected in the implanted F3-effLuc within PLLA scaffold in corticectomized area. Conclusion: We monitored the enhanced survival of the implanted F3-effLuc by support of PLLA scaffold in corticectomized rat model. We concluded that stem cell implantation using biocompatible scaffold can provide supportive effect for enhancing its viability in terms of stem cell-based therapy.