The Bill & Melinda Gates Foundation is known for spending big money to fight infectious diseases in developing countries. While that's a noble cause, the foundation isn't afraid to invest elsewhere. Earlier this year, it invested $5 million in Smart Immune to develop a technique to turn stem cells into progenitor T-cells in the lab. Once injected, these cells mature in the body, differentiating between normal cells and threats, to rebuild the patient's immune system after chemotherapy treatment.