Use of a hyaluronan and methylcellulose hydrogel to deliver neural stem cells to the stroke-injured brain

Abstract

Event Abstract Back to Event Use of a hyaluronan and methylcellulose hydrogel to deliver neural stem cells to the stroke-injured brain Samantha L. Payne1, 2*, Michael J. Cooke2*, Priya Anandakumaran2, Balazs Varga3, Cindi Morshead4*, Andras Nagy3* and Molly S. Shoichet1, 2, 5* 1 University of Toronto, Chemical Engineering and Applied Chemistry, Canada 2 University of Toronto, Institute of Biomaterials and Biomedical Engineering, Canada 3 Mount Sinai Hospital, Lunenfeld-Tanenbaum Research Institute, Canada 4 University of Toronto, Institute of Medical Science, Canada 5 University of Toronto, Department of Chemistry, Canada Introduction: Worldwide 15 million people will suffer from a stroke each year, and up to two-thirds of survivors will experience life-long functional deficits. Despite the high prevalence of stroke, no clinical treatment exists that can replace lost cells and restore function. Recent regenerative medicine strategies have focused on the delivery of an exogenous source of cells to both directly replace lost neurons and glia as well as provide trophic support to endogenous cells. While cell transplantation is a promising strategy to regenerate stroke-injured tissues, current delivery techniques suffer from low cell survival. To increase cell survival following transplantation, our lab has developed a hydrogel composed of a physical blend of hyaluronan and methylcellulose, HAMC, and demonstrated its ability to improve cell delivery and increase survival in a model of spinal cord injury[1] and retinal regeneration[2]. We hypothesize that the use of HAMC to deliver mouse or human neural precursor cells will result in improved cell survival and functional recovery in a rat model of stroke. The goals of this work are to determine if the use of HAMC can 1) maintain cell viability prior to delivery, and 2) increase cell survival and functional recovery when transplanted in vivo. Materials and Methods: HAMC hydrogels were produced using a physical blend of 0.5%/0.5% w/v sterile methylcellulose and hyaluronan reconstituted in artificial cerebralspinal fluid (aCSF). First, the ability of HAMC to improve cell survival even before transplantation was tested by encapsulating mouse precursor cells (stem and progenitors) (mNPCs) and human neuroepithelial stem cells (hNECs)[3] in 3D HAMC and left on ice for 6 or 24 hours. Next, mNPCs were delivered to a mouse stroke model to determine if HAMC promotes the survival of cells after transplantation. Lastly, we wanted to translate the work with mNPCs towards a clinically-relevant model, and so tested the use of HAMC to deliver induced pluripotent stem cell-derived hNECs into the stroke-injured rat brain. hNECs were differentiated into neural precursor cells (hNPCs) and transplanted into the stroke-injured rat brain. Results and Discussion: HAMC significantly increased mNPC and hNECs survival when cells were encapsulated in HAMC and stored on ice after 6 hours compared to aCSF. This suggests that storing cells in HAMC prior to transplantation will reduce cell death and increase the number of live cells being delivered to the brain. In mice, HAMC increased cell survival of undifferentiated mNPCs and ultimately resulted in functional recovery after endothelin-1 stroke-injury[4]. In rats, HAMC also improved survival of hNPCs in an endothelin-1 stroke-injury. In ongoing studies, we are investigating behavioural recovery in rats. Conclusions: This study demonstrates the importance of the delivery vehicle on the success of cell transplantation and tissue regeneration in the stroke-injured brain using both mouse and rat models and mouse and human neural stem cells, respectively. This contributes to the broader field of regenerative medicine. We are grateful to CIHR and NSERC for funding