Replacing dysfunctional endocrine tissues (eg, islets) with healthy, nonautologous material protected against the immune defense of the patient could soon become a reality. Recent advances have resulted in the development of alginate-based microcapsules that meet the demands of biocompatibility, long-term integrity, and function. Focus on the development of good manufacturing practice-conforming microfluidic chip technology for generation of immunoisolated transplants and on cryopreservation technology will bring the cell-based therapy to the market and clinics.