Phosphate glasses have great potential for use as biomaterials in a wide range of biomedical applications including both hard and soft tissue regeneration. In this chapter, the focus is on the use of these glasses as substrate microcarrier materials for in vitro bone cell expansion and tissue formation. The production of phosphate glass microspheres is demonstrated using a simple, inexpensive and industrially scalable process. To understand the biodegradation properties of these microspheres, a novel time-lapse imaging technique is proposed, which not only provides visual evidence of microsphere degradation, but also yields quantitative data for correlations between the degradation rate and the glass composition. The interactions between the microspheres and bone cells are investigated in cell culture plates using Transwell® inserts. The results of these studies provide evidence about the ability of the glass microspheres to function as effective substrates for bone cell scale-up and bone tissue regeneration.