Quantification and Tracking of Transplanted Satellite Cells

Abstract

Satellite cells are adult stem cells that contribute to hypertrophy and repair in muscles. It is hypothesized that in muscular dystrophy, the satellite cells population is depleted at a very early age, due to repeated muscle damage and repair. Satellite cell transplantation is a potentially useful therapy for muscle diseases, but the lack of an efficient delivery system has hindered its application. The presented work focuses on two specific aims that address the need for more effective cell delivery methods for cell-based therapy. In Specific Aim 1 enhanced tissue culture techniques, such as heat stress, are used to increase cell survival in satellite cell transplantation studies. Also addressed within this specific aim are methods to label and evaluate performance using real-time PCR techniques.Although much work remains to enhancing the viability of in vitro expanded myoblasts derived from satellite cells, a second important hurdle is the systemic delivery of satellite cells to multiple sites (all muscles, in the case of muscular dystrophies). In vitro and in vivo experiments are being undertaken to explore the physiological role of cell signaling systems involved in directed migration and to determine if these chemokine and growth factors can be manipulated to enhance efficacy of cell-based therapies involving skeletal muscle satellite cells. Specific Aim 2 addresses migration of satellite cells to sites of injury and methods to track transplanted cells within the host. Presented here is the use of FAST SPECT II imaging of 111-Indium oxine radiolabeled satellite cells. The long lifetime of 111-indium oxine and the ability to quantify label using FAST SPECT imaging techniques make this technique ideal for in-vivo tracking of transplanted satellite cells for week long studies. Without in-vivo imaging techniques cell fate studies require sequential animal sacrifice with histological sectioning. This not only increases the number of animals used but also adds a significant inter-animal variability to their assessment. The determination of cell fate after transplantation will have a major impact on cell therapy for treatment of muscle disease as well as other stem cell therapies.